AIM: To investigate the effects of rhubarb on severe acute pancreatitis (SAP) in rats. METHODS: Severe acute pancreatitis was induced by two intraperitoneal injections of cerulein (40 μg/kg body weight) plus 5-h rest...AIM: To investigate the effects of rhubarb on severe acute pancreatitis (SAP) in rats. METHODS: Severe acute pancreatitis was induced by two intraperitoneal injections of cerulein (40 μg/kg body weight) plus 5-h restraint water-immersion stress. Rhubarb (75-150 mg/kg) was orally fed before the first cerulein injection. The degree of pancreatic edema, serum amylase level, local pancreatic blood flow (PBF), and histological alterations were investigated. The effects of rhubarb on pancreatic exocrine secretion in this model were evaluated by comparing with those of somatostatin. RESULTS: In the Cerulein+Stress group, severe edema and diffuse hemorrhage in the pancreas were observed, the pancreatic wet weight (11.60±0.61 g/Kg) and serum amylase (458 490±43 100 U/L) were markedly increased (P<0.01 vs control). In the rhubarb (150 mg/kg) treated rats, necrosis and polymorphonuclear neutrophil (PMN) infiltration in the pancreas were significantly reduced (P<0.01), and a marked decrease (50%) in serum amylase levels was also observed (P<0.01). PBF dropped to 38% (93±5 mL/min per 100 g) of the control in the Cerulein+Stress group and partly recovered in the Cerulein+Stress+Rhubarb 150 mg group (135±12 mL/min per 100 g) (P<0.01). The pancreatic exocrine function was impaired in the SAP rats. The amylase levels of pancreatic juice were reduced in the rats treated with rhubarb or somatostatin, comparing with that of untreated SAP group. The bicarbonate concentration of pancreatic juice was markedly elevated only in the rhubarbtreated group (P<0.01). CONCLUSION: Rhubarb can exert protective effects on SAP, probably by inhibiting the inflammation of pancreas, improving pancreatic microcirculation, and altering exocrine secretion.展开更多
There has been a long-standing need for guidelines on the diagnosis and treatment of keloids and hypertrophic scars that are based on an understanding of the pathomechanisms that underlie these skin fibrotic diseases....There has been a long-standing need for guidelines on the diagnosis and treatment of keloids and hypertrophic scars that are based on an understanding of the pathomechanisms that underlie these skin fibrotic diseases.This is particularly true for clinicians who deal with Asian and African patients because these ethnicities are highly prone to these diseases.By contrast,Caucasians are less likely to develop keloids and hypertrophic scars,and if they do,the scars tend not to be severe.This ethnic disparity also means that countries vary in terms of their differential diagnostic algorithms.The lack of clear treatment guidelines also means that primary care physicians are currently applying a hotchpotch of treatments,with uneven outcomes.To overcome these issues,the Japan Scar Workshop(JSW)has created a tool that allows clinicians to objectively diagnose and distinguish between keloids,hypertrophic scars,and mature scars.This tool is called the JSW Scar Scale(JSS)and it involves scoring the risk factors of the individual patients and the affected areas.The tool is simple and easy to use.As a result,even physicians who are not accustomed to keloids and hypertrophic scars can easily diagnose them and judge their severity.The JSW has also established a committee that,in cooperation with outside experts in various fields,has prepared a Consensus Document on keloid and hypertrophic scar treatment guidelines.These guidelines are simple and will allow even inexperienced clinicians to choose the most appropriate treatment strategy.The Consensus Document is provided in this article.It describes(1)the diagnostic algorithm for pathological scars and how to differentiate them from clinically similar benign and malignant tumors,(2)the general treatment algorithms for keloids and hypertrophic scars at different medical facilities,(3)the rationale behind each treatment for keloids and hypertrophic scars,and(4)the body site-specific treatment protocols for these scars.We believe that this Consensus Document will be helpful for physi展开更多
The incidence of prostate cancer(PCa)within Asian population used to be much lower than in the Western population;however,in recent years the incidence and mortality rate of PCa in some Asian countries have grown rapi...The incidence of prostate cancer(PCa)within Asian population used to be much lower than in the Western population;however,in recent years the incidence and mortality rate of PCa in some Asian countries have grown rapidly.This collaborative report summarized the latest epidemiology information,risk factors,and racial differences in PCa diagnosis,current status and new trends in surgery management and novel agents for castration-resistant prostate cancer.We believe such information would be helpful in clinical decision making for urologists and oncologists,health-care ministries and medical researchers.展开更多
Endoscopic submucosal dissection (ESD) is now the most common endoscopic treatment in Japan for intramucosal gastrointestinal neoplasms (non-metastatic). ESD is an invasive endoscopic surgical procedure, requiring ex... Endoscopic submucosal dissection (ESD) is now the most common endoscopic treatment in Japan for intramucosal gastrointestinal neoplasms (non-metastatic). ESD is an invasive endoscopic surgical procedure, requiring extensive knowledge, skill, and specialized equipment. ESD starts with evaluation of the lesion, as accurate assessment of the depth and margin of the lesion is essential. The devices and strategies used in ESD vary, depending on the nature of the lesion. Prior to the procedure, the operator must be knowledgeable about the treatment strategy(ies), the device(s) to use, the electrocautery machine settings, the substances to inject, and other aspects. In addition, the operator must be able to manage complications, should they arise, including immediate recognition of the complication(s) and its treatment. Finally, in case the ESD treatment is not successful, the operator should be prepared to apply alternative treatments. Thus, adequate knowledge and training are essential to successfully perform ESD.展开更多
The generalized fractional element networks are presented in this paper. In order to extend the structure of the model solutions to the generalized function space and make it contain more physical meanings, the restri...The generalized fractional element networks are presented in this paper. In order to extend the structure of the model solutions to the generalized function space and make it contain more physical meanings, the restriction on the parameters of the fractional element proposed by Schiessel et al. is eliminated and a 'compatibility equation' is added. The discretization method for solving the inverse Laplace transform is used and developed. The generalized solutions of the model equations are given. At the same time the generalized fractional element network--Zener and Poyinting-Thomson models are discussed in detail. It is shown that all the results obtained previously about the models of single parameter with fractional order and the classical models with integer order can be contained as the special cases of the results of this paper.展开更多
Development of new materials with high hydrogen storage capacity and reversible hydrogen sorp-tion performances under mild conditions has very high value in both fundamental and application aspects.In the past years,s...Development of new materials with high hydrogen storage capacity and reversible hydrogen sorp-tion performances under mild conditions has very high value in both fundamental and application aspects.In the past years,some new systems with metastable structures,such as ultra-fine nanocrystalline alloys,amorphous alloys,nanoglass alloys,immiscible alloys,high-entropy alloys,have been abundantly studied as hydrogen storage mate-rials.Many new hydrogen storage properties either from the kinetics or thermodynamics aspects have been reported.In this review,recent advances of studies on metastable alloys for hydrogen storage applications have been comprehensively reviewed.The materials preparation methods to synthesize metastable hydrogen storage alloys are firstly reviewed.Afterwards,hydrogen storage prop-erties of the metastable alloys are summarized and dis-cussed,focusing on the unique kinetics and thermodynamics properties by forming of such unique metastable structures.For examples,superior hydrogena-tion kinetics and higher hydrogen storage capacity have been achieved in Mg-based amorphous and nanoglass alloys.Destabilized thermodynamics properties can be obtained in the immiscible Mg-Mn and Mg-Zr alloys.In addition to highlighting the recent achievements of metastable alloys in the field of hydrogen storage,the remaining challenges and trends of the emerging research are also discussed.展开更多
AIM: To assess the utility and safety of single-operator cholangiopancreatoscopy(SOCPS) using the Spy Glass system in widespread clinical application for biliary and pancreatic diseases.METHODS: This study was a prosp...AIM: To assess the utility and safety of single-operator cholangiopancreatoscopy(SOCPS) using the Spy Glass system in widespread clinical application for biliary and pancreatic diseases.METHODS: This study was a prospective case series conducted in 20 referral centers in Japan. There were 148 patients who underwent SOCPS; 124 for biliary diseases and 24 for pancreatic diseases. The attempted interventions were SOCPS examination, SOCPS-directed tissue sampling, and therapy for stone removal, among others. The main outcomes were related to the procedure success rate in terms of visualizing the target lesions, SOCPS-directed adequate tissue sampling, and complete stone removal. RESULTS: A total of 148 patients were enrolled for the diagnosis of indeterminate biliary and pancreatic lesions or treatment of biliary and pancreatic disease. The overall procedure success rate of visualizing the target lesions was 91.2%(135/148). The overall procedural success rates of visualizing the target lesions of diagnostic SOCPS in the bile duct and pancreatic duct were 95.5%(84/89) and 88.2%(15/17), respectively. Diagnosis: the overall adequate tissue for histologic examination was secured in 81.4% of the 86 patients who underwent biopsy under SOCPS(bile duct, 60/75, 80.0%; pancreatic duct, 10/11, 90.9%). The accuracy of histologic diagnosis using SOCPS-directed biopsies in indeterminate bile duct lesions was 70.7%(53/75). In the pancreatic duct, the accuracy of SOCPS visual impression of intraductal papillary mucinous neoplasm was 87.5%(14/16). Stone therapy: complete biliary and pancreatic stone clearance combined with SOCPS-directed stone therapy using electrohydraulic lithotripsy or laser lithotripsy was achieved in 74.2%(23/31) and 42.9%(3/7) of the patients, respectively. Others: SOCPS using the Spy Glass system was used in cannulation of the cystic duct in two patients and for passing across the obstructed self-expandable metallic stent for a malignant biliary stricture in two patients. All procedures were successful in both展开更多
AIM： Minimal deviation carcinoma of the uterine cervix, otherwise known as extremely well-differentiated adenocarcinoma （EWDA）, is characterized by its benign microscopic appearance in contrast to its aggressive be...AIM： Minimal deviation carcinoma of the uterine cervix, otherwise known as extremely well-differentiated adenocarcinoma （EWDA）, is characterized by its benign microscopic appearance in contrast to its aggressive behavior. In order to elucidate the clinicopathological features and biological behavior of the gastric counterpart of EWDA, we, using immunohistochemistry, analyzed nine lesions for the phenotypic expression, proliferative activity, and the expression of oncogene-associated products. METHODS： Clinicopathological features, including preoperative biopsy diagnosis, were reviewed. Using immunohitstochemistry, Ki-67 labeling index and expression of p53 and c-erbB-2 protein in the gastric lesions were detected.RESULT： Locations in the middle or upper third of the stomach and polypoid macroscopic features are characteristic of EWDA of the stomach. Although 4 of the 9 lesions showed only focal lymphatic or venous invasion, lymph node metastasis was not present and none of the patients died of the lesions （mean follow-up period, 56 too）. All 9 cases of EWDA could be classified into gastric phenotype （5 lesions） and intestinal phenotype （4 lesions）. The former resembled gastric foveolar epithelium, mucous neck cells or pyloric glands, but their papillary structures were frequently elongated and the tumor cellsand their nuclei were slightly larger and more hyperchromatic compared to normal epithelium. The latter resembled intestinal metaplasia with minimal nulcear atypia and irregular glands; two of these lesions demonstrated complete intestinal phenotype, while two demonstrated incomplete intestinal phenotype. Ki-67 labeling index was low and none of the cases revealed over-expression of p53 and c-erbB-2 protein. CONCLUSION： Unlike minimal deviation carcinoma of the cervix, these findings suggest that EWDA of the stomach is a lesion of low-grade malignancy. This favorable biological behavior is supported by the data of a low Ki-67 labeling index and a lack of p53 or c-erbB-2 protein over-ex展开更多
Numerical simulations of extreme wave generation are carried out by using the Volume Of Fluid（VOF） method.Extreme waves are generated based on wave focusing in a 2-D numerical model.To validate the capability of the...Numerical simulations of extreme wave generation are carried out by using the Volume Of Fluid（VOF） method.Extreme waves are generated based on wave focusing in a 2-D numerical model.To validate the capability of the VOF-based model described in this article,the propagation of regular waves is computed and compared with the theoretical results.By adjusting the phases of wave components,extreme waves are formed at given time and given position in the computation.The numerical results are compared with theoretical solutions and experimental data.It is concluded that the present model based on the VOF technique can provide acceptably accurate numerical results to serve practical purposes.展开更多
AIM： To evaluate the efficacy of continuous regional arterial infusion therapy （CRAI） with gabexate mesilate and antibiotics for severe acute pancreatitis （SAP）. METHODS： We conducted a prospective study on pati...AIM： To evaluate the efficacy of continuous regional arterial infusion therapy （CRAI） with gabexate mesilate and antibiotics for severe acute pancreatitis （SAP）. METHODS： We conducted a prospective study on patients who developed SAP with or without CRAI. Out of 18 patients fulfilled clinical diagnostic criteria for SAP in Japan, 9 patients underwent CRAI, while 9 patients underwent conventional systemic protease inhibitor and antibiotics therapy （non-CRAI）. CRAI was initiated within 72 h of the onset of pancreatitis. Gabexate mesilate （2400 mg/d） was continuously administered for 3 to 5 d. The clinical outcome including serum inflammation-related parameters were examined. RESULTS- The duration of abdominal pain in the CRAI group was 1.9 =1：0.26 d, whereas that in the non-CRAI group was 4.3 ±0.50. The duration of SIRS in the CRAI group was 2.2 ± 0.22 d, whereas that in the non- CRAI group was 3.2 ± 0.28. Abdominal pain and SIRS disappeared significantly in a short period of time after the initiation of CRAI using gabexate mesilate. The average length of hospitalization significantly differed between the CRAI and non-CRAI groups, 53.3 ± 7.9 d and 87.4± 13.9 d, respectively. During the first two weeks, levels of serum CRP and the IL6/IL10 ratio in the CRAI group tended to have a rapid decrease compared to those in the non-CRAI group. CONCLUSION： The present results suggest that CRAI using gabexate mesilate was effective against SAP.展开更多
The etiology of inflammatory bowel disease （IBD） has not yet been clarified and immunosuppressive agents which non-specifically reduce inflammation and immunity have been used in the conventional therapies for IBD. ...The etiology of inflammatory bowel disease （IBD） has not yet been clarified and immunosuppressive agents which non-specifically reduce inflammation and immunity have been used in the conventional therapies for IBD. Evidence indicates that a dysregulation of mucosal immunity in the gut of IBD causes an overproduction of inflammatory cytokines and trafficking of effector leukocytes into the bowel, thus leading to an uncontrolled intestinal inflammation. Such recent advances in the understanding of the pathogenesis of IBD created a recent trend of novel biological therapies which specifically inhibit the molecules involved in the inflammatory cascade. Major targets for such treatment are inflammatory cytokines and their receptors, and adhesion molecules. A chimeric anti-TNF-α monoclonal antibody, infiiximab, has become a standard therapy for CD and it is also likely to be beneficial for UC. Several anti-TNF reagents have been developed but most of them seem to not be as efficacious as infliximab. A humanized anti-TNF monoclonal antibody, adalimumab may be useful for the treatment of patients who lost responsiveness or developed intolerance to infliximab. Antibodies against IL-12 p40 and IL-6 receptor could be alternative new anti-cytokine therapies for IBD. Antiinterferon-γ and anti-CD25 therapies were developed, but the benefit of these agents has not yet been established. The selective blocking of migration of leukocytes into intestine seems to be a nice approach. Antibodies against α4 integrin and α4β7 integrin showed benefit for IBD. Antisense oligonucleotide of intercellular adhesion molecule 1 （ICAM-1） may be efficacious for IBD. Clinical trials of such compounds have been either recently reported or are currently underway. In this article, we review the efficacy and safety of such novel biological therapies for IBD.展开更多
Gastric cancer is the second most common of cancerrelated deaths worldwide.In the majority of cases gastric cancer is advanced at diagnosis and although medical and surgical treatments have improved,survival rates rem...Gastric cancer is the second most common of cancerrelated deaths worldwide.In the majority of cases gastric cancer is advanced at diagnosis and although medical and surgical treatments have improved,survival rates remain poor.Cancer immunotherapy has emerged as a powerful and promising clinical approach for treatment of cancer and has shown major success in breast cancer,prostate cancer and melanoma.Here,we provide an overview of concepts of modern cancer immunotherapy including the theory,current approaches,remaining hurdles to be overcome,and the future prospect of cancer immunotherapy in the treatment of gastric cancer.Adaptive cell therapies,cancer vaccines,gene therapies,monoclonal antibody therapies have all been used with some initial successes in gastric cancer.However,to date the results in gastric cancer have been disappointing as current approaches often do not stimulate immunity efficiently allowing tumors continue to grow despite the presence of a measurable immune response.Here,we discuss the identification of targets for immunotherapy and the role of biomarkers in prospectively identifying appropriate subjects or immunotherapy.We also discuss the molecular mechanisms by which tumor cells escape host immunosurveillance and produce an immunosuppressive tumor microenvironment.We show how advances have provided tools for overcoming the mechanisms of immunosuppression including the use of monoclonal antibodies to block negative regulators normally expressed on the surface of T cells which limit activation and proliferation of cytotoxic T cells.Immunotherapy has greatly improved and is becoming an important factor in such fields as medical care and welfare for human being.Progress has been rapid ensuring that the future of immunotherapy for gastric cancer is bright.展开更多
Thrombocytopenia is a common complication in liver disease and can adversely affect the treatment of liver cirrhosis,limiting the ability to administer therapy and delaying planned surgical/diagnostic procedures becau...Thrombocytopenia is a common complication in liver disease and can adversely affect the treatment of liver cirrhosis,limiting the ability to administer therapy and delaying planned surgical/diagnostic procedures because of an increased risk of bleeding.Multiple factors,including splenic sequestration,reduced activity of the hematopoietic growth factor thrombopoietin,bone marrow suppression by chronic hepatitis C virus infection and anti-cancer agents,and antiviral treatment with interferon-based therapy,can contribute to the development of thrombocytopenia in cirrhotic patients.Of these factors,the major mechanisms for thrombocytopenia in liver cirrhosis are(1)platelet sequestration in the spleen;and(2)decreased production of thrombopoietin in the liver.Several treatment options,including platelet transfusion,interventional partial splenic embolization,and surgical splenectomy,are now available for severe thrombocytopenia in cirrhotic patients.Although thrombopoietin agonists and targeted agents are alternative tools for noninvasively treating thrombocytopenia due to liver cirrhosis,their ability to improve thrombocytopenia in cirrhotic patients is under investigation in clinical trials.In this review,we propose a treatment approach to thrombocytopenia according to our novel concept of splenic volume,and we describe the current management of thrombocytopenia due to liver cirrhosis.展开更多
Molecular mechanisms of hybrid breakdown associated with sterility (F<sub>2</sub> sterility) are poorly understood as compared with those of F<sub>1</sub> hybrid sterility. Previously, we chara...Molecular mechanisms of hybrid breakdown associated with sterility (F<sub>2</sub> sterility) are poorly understood as compared with those of F<sub>1</sub> hybrid sterility. Previously, we characterized three unlinked epistatic loci, hybrid sterility-a1 (hsa1), hsa2, and hsa3, responsible for the F<sub>2</sub> sterility in a cross between Oryza sativa ssp. indica and japonica. In this study, we identified that the hsa1 locus contains two interacting genes, HSA1a and HSA1b, within a 30-kb region. HSA1a-j (japonica allele) encodes a highly conserved plant-specific domain of unknown function protein (DUF1618), whereasthe indica allele (HSA1a-i<sup>s</sup>) has two deletion mutations that cause disruption of domain structure. The second gene, HSA1b-i<sup>s</sup>, encodes an uncharacterized proteinwith some similarity to a nucleotide-binding protein. Homozygous introgression of indica HSA1a-i<sup>s</sup>-HSA1b-i<sup>s</sup> alleles into japonica showed female gamete abortion at an early mitotic stage. The fact that the recombinant haplotype HSA1a-j-HSA1b-i<sup>s</sup> caused semi-sterility in the heterozygous state with the HSA1a-i<sup>s</sup>-HSA1b-i<sup>s</sup> haplotype suggests that variation in the hsa1 locus is a possible cause of the wide-spectrum sterility barriers seen in F<sub>1</sub> hybrids and successive generations in rice. We propose a simple genetic model to explain how a single causal mechanism can drive both F<sub>1</sub> and F<sub>2</sub> hybrid sterility.展开更多
AIM: To elucidate the immunologic parameters for the outcome of patients with malignant tumors, especially esophageal squamous cell carcinoma (ESCC) associated with high malignant potential. METHODS: Clinicopathologic...AIM: To elucidate the immunologic parameters for the outcome of patients with malignant tumors, especially esophageal squamous cell carcinoma (ESCC) associated with high malignant potential. METHODS: Clinicopathologic features were compared between patients with lower and higher CD4 and CD8 values as well as CD4/CD8 ratio in peripheral blood. RESULTS: The survival rate of patients with higher CD4 value was significantly better than that in patients with lower CD4 value (P = 0.039). The survival rate of patients with higher CD8 value was significantly worse than that of patients with lower CD8 value (P = 0.026). Similarly, the survival rate of patients with higher CD4/ CD8 ratio was significantly better than that of patients with lower CD4/CD8 ratio (P = 0.042). Additionally, multivariate analysis demonstrated that lower CD8 and lower CD4/CD8 ratio were factors independently associated with worse prognosis of patients. CONCLUSION: All the immunologic parameters can predict the outcome of patients with ESCC.展开更多
AIM:To assess the clinicopathologic characteristics,risk factors,and prognosis for synchronous multiple early gastric cancer(SMGC).METHODS:A total of 146 patients with SMGC and1194 patients with single gastric cancer ...AIM:To assess the clinicopathologic characteristics,risk factors,and prognosis for synchronous multiple early gastric cancer(SMGC).METHODS:A total of 146 patients with SMGC and1194 patients with single gastric cancer who had undergone gastrectomy between 1989 and 2008 were retrospectively analyzed to determine their clinicopathologic characteristics and postoperative survival.Tumors were classified into groups on the basis of location and histology.Smoking habits were evaluated using the Brinkman index.Clinical and pathological factors were compared using either Fisher’s exact test or Pearson’sχ2test.Logistic regression analysis was performed to identify independent risk factors.Survival rate was calculated using the Kaplan-Meier method.RESULTS:SMGCs accounted for 10.9%of gastric cancer cases and occurred predominantly in elderly male patients with a family history of gastric cancer who were both smokers and drinkers.These tumors were typically macroscopically elevated and histologically differentiated.There were no significant differences between SMGC and single gastric cancer patients with respect to tumor location,tumor size,lymph node metastasis,the number of metastatic lymph nodes,venous invasion,or tumor stage(P=0.052,P=0.347,P=0.595,P=0.805,P=0.559,and P=0.408,respectively).Further,there was no significant difference in postoperative survival between the patient groups(P=0.200).Of the 146SMGC patients,a single patient had remnant cancer.CONCLUSION:A careful preoperative endoscopy is necessary for patients who are at high risk of SMGC,and minimally invasive treatment may be indicated in some cases.展开更多
Pancreatic cancer is one of the most aggressive and difficult cancers to treat.Despite numerous research efforts,limited success has been achieved in the therapeutic management of patients with this disease.In the cur...Pancreatic cancer is one of the most aggressive and difficult cancers to treat.Despite numerous research efforts,limited success has been achieved in the therapeutic management of patients with this disease.In the current review,we focus on one component of morphogenesis signaling,Hedgehog(Hh),with the aim of developing novel,effective therapies for the treatment of pancreatic cancer.Hh signaling contributes to the induction of a malignant phenotype in pancreatic cancer and is responsible for maintaining pancreatic cancer stem cells.In addition,we propose a novel concept linking Hh signaling and tumor hypoxic conditions,and discuss the effects of Hh inhibitors in clinical trials.The Hh signaling pathway may represent a potential therapeutic target for patients with refractory pancreatic cancer.展开更多
This paper presents a coordination strategy of Load Frequency Control(LFC)and digital frequency protection for an islanded microgrid(MG)considering high penetration of Renewable Energy Sources(RESs).In such MGs,the re...This paper presents a coordination strategy of Load Frequency Control(LFC)and digital frequency protection for an islanded microgrid(MG)considering high penetration of Renewable Energy Sources(RESs).In such MGs,the reduction in system inertia due to integration of large amount of RESs causes undesirable influence on MG frequency stability,leading to weakening of the MG.Furthermore,sudden load events,and short circuits caused large frequency fluctuations,which threaten the system security and could lead to complete blackouts as well as damages to the system equipment.Therefore,maintaining the dynamic security in MGs is one of the important challenges,which considered in this paper using a specific design and various data conversion stages of a digital over/under frequency relay(OUFR).The proposed relay will cover both under and over frequency conditions in coordination with LFC operation to protect the MG against high frequency variations.To prove the response of the proposed coordination strategy,a small MG was investigated for the simulation.The proposed coordination method has been tested considering load change,high integration of RESs.Moreover,the sensitivity analysis of the presented technique was examined by varying the penetration level of RESs and reducing the system inertia.The results reveal the effectiveness of the proposed coordination to maintain the power system frequency stability and security.In addition,the superiority of the OUFR has been approved in terms of accuracy and speed response during high disturbances.展开更多
An application of contra-rotating rotors has been proposed against a demand for developing higher specific speed axial flow pump. In the present paper, the advantage and disadvantage of using contra-rotating rotors ar...An application of contra-rotating rotors has been proposed against a demand for developing higher specific speed axial flow pump. In the present paper, the advantage and disadvantage of using contra-rotating rotors are described in comparison with conventional type of rotor-stator, based on theoretical and experimental investigations. The advantages are as follows： （1） The pump is inherently designed as smaller sized and at lower rotational speed. （2） A stable head-characteristic curve for flow rate with negative slope appears. （3） As the rear rotor rotational speed is varied as independent control of front rotor, the wider range of high performance operation is obtained by rear rotor speed control in addition to front rotor speed control. The disadvantages are as follows： （1） The structure of double shaft system becomes complex. （2） The pump performance is inferior at over flow rate as the rear rotor loading is weakened. （3） The blade rows interaction from rear rotor to front rotor more strongly appears. Then the rear rotor design is a key to achieve higher pump performance. Some methods to overcome these disadvantages will be discussed in more details toward wider usage of contra-rotating axial flow pump in various industrial fields.展开更多
文摘AIM: To investigate the effects of rhubarb on severe acute pancreatitis (SAP) in rats. METHODS: Severe acute pancreatitis was induced by two intraperitoneal injections of cerulein (40 μg/kg body weight) plus 5-h restraint water-immersion stress. Rhubarb (75-150 mg/kg) was orally fed before the first cerulein injection. The degree of pancreatic edema, serum amylase level, local pancreatic blood flow (PBF), and histological alterations were investigated. The effects of rhubarb on pancreatic exocrine secretion in this model were evaluated by comparing with those of somatostatin. RESULTS: In the Cerulein+Stress group, severe edema and diffuse hemorrhage in the pancreas were observed, the pancreatic wet weight (11.60±0.61 g/Kg) and serum amylase (458 490±43 100 U/L) were markedly increased (P<0.01 vs control). In the rhubarb (150 mg/kg) treated rats, necrosis and polymorphonuclear neutrophil (PMN) infiltration in the pancreas were significantly reduced (P<0.01), and a marked decrease (50%) in serum amylase levels was also observed (P<0.01). PBF dropped to 38% (93±5 mL/min per 100 g) of the control in the Cerulein+Stress group and partly recovered in the Cerulein+Stress+Rhubarb 150 mg group (135±12 mL/min per 100 g) (P<0.01). The pancreatic exocrine function was impaired in the SAP rats. The amylase levels of pancreatic juice were reduced in the rats treated with rhubarb or somatostatin, comparing with that of untreated SAP group. The bicarbonate concentration of pancreatic juice was markedly elevated only in the rhubarbtreated group (P<0.01). CONCLUSION: Rhubarb can exert protective effects on SAP, probably by inhibiting the inflammation of pancreas, improving pancreatic microcirculation, and altering exocrine secretion.
文摘There has been a long-standing need for guidelines on the diagnosis and treatment of keloids and hypertrophic scars that are based on an understanding of the pathomechanisms that underlie these skin fibrotic diseases.This is particularly true for clinicians who deal with Asian and African patients because these ethnicities are highly prone to these diseases.By contrast,Caucasians are less likely to develop keloids and hypertrophic scars,and if they do,the scars tend not to be severe.This ethnic disparity also means that countries vary in terms of their differential diagnostic algorithms.The lack of clear treatment guidelines also means that primary care physicians are currently applying a hotchpotch of treatments,with uneven outcomes.To overcome these issues,the Japan Scar Workshop(JSW)has created a tool that allows clinicians to objectively diagnose and distinguish between keloids,hypertrophic scars,and mature scars.This tool is called the JSW Scar Scale(JSS)and it involves scoring the risk factors of the individual patients and the affected areas.The tool is simple and easy to use.As a result,even physicians who are not accustomed to keloids and hypertrophic scars can easily diagnose them and judge their severity.The JSW has also established a committee that,in cooperation with outside experts in various fields,has prepared a Consensus Document on keloid and hypertrophic scar treatment guidelines.These guidelines are simple and will allow even inexperienced clinicians to choose the most appropriate treatment strategy.The Consensus Document is provided in this article.It describes(1)the diagnostic algorithm for pathological scars and how to differentiate them from clinically similar benign and malignant tumors,(2)the general treatment algorithms for keloids and hypertrophic scars at different medical facilities,(3)the rationale behind each treatment for keloids and hypertrophic scars,and(4)the body site-specific treatment protocols for these scars.We believe that this Consensus Document will be helpful for physi
基金supported by the Program for Changjiang Scholars and Innovative Research Team in University scheme of the Ministry of Education of China(NO.IRT1111)the National Basic Research Program of China(2012CB518300)+2 种基金the National Natural Science Foundation of China(81101946)the Shanghai Pujiang Program(12PJD008)Prostate Cancer Foundation Young Investigator Award,Shanghai Municipal Health and Family Planning Commission Outstanding Young Investigator(XYQ2013077).
文摘The incidence of prostate cancer(PCa)within Asian population used to be much lower than in the Western population;however,in recent years the incidence and mortality rate of PCa in some Asian countries have grown rapidly.This collaborative report summarized the latest epidemiology information,risk factors,and racial differences in PCa diagnosis,current status and new trends in surgery management and novel agents for castration-resistant prostate cancer.We believe such information would be helpful in clinical decision making for urologists and oncologists,health-care ministries and medical researchers.
文摘 Endoscopic submucosal dissection (ESD) is now the most common endoscopic treatment in Japan for intramucosal gastrointestinal neoplasms (non-metastatic). ESD is an invasive endoscopic surgical procedure, requiring extensive knowledge, skill, and specialized equipment. ESD starts with evaluation of the lesion, as accurate assessment of the depth and margin of the lesion is essential. The devices and strategies used in ESD vary, depending on the nature of the lesion. Prior to the procedure, the operator must be knowledgeable about the treatment strategy(ies), the device(s) to use, the electrocautery machine settings, the substances to inject, and other aspects. In addition, the operator must be able to manage complications, should they arise, including immediate recognition of the complication(s) and its treatment. Finally, in case the ESD treatment is not successful, the operator should be prepared to apply alternative treatments. Thus, adequate knowledge and training are essential to successfully perform ESD.
基金the Doctoral Program Foundation of the Ministry of Education of China,the National Natural Science Foundation of China(Grant Nos.10272067 and 10002003)the Foundation for University Key Teacher by the Ministry of Education.
文摘The generalized fractional element networks are presented in this paper. In order to extend the structure of the model solutions to the generalized function space and make it contain more physical meanings, the restriction on the parameters of the fractional element proposed by Schiessel et al. is eliminated and a 'compatibility equation' is added. The discretization method for solving the inverse Laplace transform is used and developed. The generalized solutions of the model equations are given. At the same time the generalized fractional element network--Zener and Poyinting-Thomson models are discussed in detail. It is shown that all the results obtained previously about the models of single parameter with fractional order and the classical models with integer order can be contained as the special cases of the results of this paper.
基金financially supported by Guangdong Basic and Applied Basic Research Foundation (No. 2019A1515011985)the National Natural Science Foundation of China (Nos.52071157,51801078,52001070 and 52001079)+3 种基金the Natural Science Foundation of Jiangsu Province (No.BK20180986)the Natural Science Foundation of Guangxi Province (No. 2019GXNSFB A185004)Guangzhou Science and Technology Association Young Talent Lifting Project (No.X20200301071)the Open Fund of the Guangdong Provincial Key Laboratory of Advance Energy Storage Materials (No.AESM202102)
文摘Development of new materials with high hydrogen storage capacity and reversible hydrogen sorp-tion performances under mild conditions has very high value in both fundamental and application aspects.In the past years,some new systems with metastable structures,such as ultra-fine nanocrystalline alloys,amorphous alloys,nanoglass alloys,immiscible alloys,high-entropy alloys,have been abundantly studied as hydrogen storage mate-rials.Many new hydrogen storage properties either from the kinetics or thermodynamics aspects have been reported.In this review,recent advances of studies on metastable alloys for hydrogen storage applications have been comprehensively reviewed.The materials preparation methods to synthesize metastable hydrogen storage alloys are firstly reviewed.Afterwards,hydrogen storage prop-erties of the metastable alloys are summarized and dis-cussed,focusing on the unique kinetics and thermodynamics properties by forming of such unique metastable structures.For examples,superior hydrogena-tion kinetics and higher hydrogen storage capacity have been achieved in Mg-based amorphous and nanoglass alloys.Destabilized thermodynamics properties can be obtained in the immiscible Mg-Mn and Mg-Zr alloys.In addition to highlighting the recent achievements of metastable alloys in the field of hydrogen storage,the remaining challenges and trends of the emerging research are also discussed.
文摘AIM: To assess the utility and safety of single-operator cholangiopancreatoscopy(SOCPS) using the Spy Glass system in widespread clinical application for biliary and pancreatic diseases.METHODS: This study was a prospective case series conducted in 20 referral centers in Japan. There were 148 patients who underwent SOCPS; 124 for biliary diseases and 24 for pancreatic diseases. The attempted interventions were SOCPS examination, SOCPS-directed tissue sampling, and therapy for stone removal, among others. The main outcomes were related to the procedure success rate in terms of visualizing the target lesions, SOCPS-directed adequate tissue sampling, and complete stone removal. RESULTS: A total of 148 patients were enrolled for the diagnosis of indeterminate biliary and pancreatic lesions or treatment of biliary and pancreatic disease. The overall procedure success rate of visualizing the target lesions was 91.2%(135/148). The overall procedural success rates of visualizing the target lesions of diagnostic SOCPS in the bile duct and pancreatic duct were 95.5%(84/89) and 88.2%(15/17), respectively. Diagnosis: the overall adequate tissue for histologic examination was secured in 81.4% of the 86 patients who underwent biopsy under SOCPS(bile duct, 60/75, 80.0%; pancreatic duct, 10/11, 90.9%). The accuracy of histologic diagnosis using SOCPS-directed biopsies in indeterminate bile duct lesions was 70.7%(53/75). In the pancreatic duct, the accuracy of SOCPS visual impression of intraductal papillary mucinous neoplasm was 87.5%(14/16). Stone therapy: complete biliary and pancreatic stone clearance combined with SOCPS-directed stone therapy using electrohydraulic lithotripsy or laser lithotripsy was achieved in 74.2%(23/31) and 42.9%(3/7) of the patients, respectively. Others: SOCPS using the Spy Glass system was used in cannulation of the cystic duct in two patients and for passing across the obstructed self-expandable metallic stent for a malignant biliary stricture in two patients. All procedures were successful in both
基金Supported by Grants-in-aid for Cancer Research from the Ministry of Education, Science and Culture, Japan and the Fukuoka Cancer Society, Fukuoka, Japan
文摘AIM： Minimal deviation carcinoma of the uterine cervix, otherwise known as extremely well-differentiated adenocarcinoma （EWDA）, is characterized by its benign microscopic appearance in contrast to its aggressive behavior. In order to elucidate the clinicopathological features and biological behavior of the gastric counterpart of EWDA, we, using immunohistochemistry, analyzed nine lesions for the phenotypic expression, proliferative activity, and the expression of oncogene-associated products. METHODS： Clinicopathological features, including preoperative biopsy diagnosis, were reviewed. Using immunohitstochemistry, Ki-67 labeling index and expression of p53 and c-erbB-2 protein in the gastric lesions were detected.RESULT： Locations in the middle or upper third of the stomach and polypoid macroscopic features are characteristic of EWDA of the stomach. Although 4 of the 9 lesions showed only focal lymphatic or venous invasion, lymph node metastasis was not present and none of the patients died of the lesions （mean follow-up period, 56 too）. All 9 cases of EWDA could be classified into gastric phenotype （5 lesions） and intestinal phenotype （4 lesions）. The former resembled gastric foveolar epithelium, mucous neck cells or pyloric glands, but their papillary structures were frequently elongated and the tumor cellsand their nuclei were slightly larger and more hyperchromatic compared to normal epithelium. The latter resembled intestinal metaplasia with minimal nulcear atypia and irregular glands; two of these lesions demonstrated complete intestinal phenotype, while two demonstrated incomplete intestinal phenotype. Ki-67 labeling index was low and none of the cases revealed over-expression of p53 and c-erbB-2 protein. CONCLUSION： Unlike minimal deviation carcinoma of the cervix, these findings suggest that EWDA of the stomach is a lesion of low-grade malignancy. This favorable biological behavior is supported by the data of a low Ki-67 labeling index and a lack of p53 or c-erbB-2 protein over-ex
基金support by the National Natural Science Foundation of China (Grant No. 50779004)
文摘Numerical simulations of extreme wave generation are carried out by using the Volume Of Fluid（VOF） method.Extreme waves are generated based on wave focusing in a 2-D numerical model.To validate the capability of the VOF-based model described in this article,the propagation of regular waves is computed and compared with the theoretical results.By adjusting the phases of wave components,extreme waves are formed at given time and given position in the computation.The numerical results are compared with theoretical solutions and experimental data.It is concluded that the present model based on the VOF technique can provide acceptably accurate numerical results to serve practical purposes.
基金Supported by Grant from the Ministry of Education, Culture, Sports, Science, and Technology, Japan, No. 20590808The Research Committee of Intractable Diseases of the Pancreas, provided by the Ministry of Health, Labour, and Welfare Japan, No. 50253448
文摘AIM： To evaluate the efficacy of continuous regional arterial infusion therapy （CRAI） with gabexate mesilate and antibiotics for severe acute pancreatitis （SAP）. METHODS： We conducted a prospective study on patients who developed SAP with or without CRAI. Out of 18 patients fulfilled clinical diagnostic criteria for SAP in Japan, 9 patients underwent CRAI, while 9 patients underwent conventional systemic protease inhibitor and antibiotics therapy （non-CRAI）. CRAI was initiated within 72 h of the onset of pancreatitis. Gabexate mesilate （2400 mg/d） was continuously administered for 3 to 5 d. The clinical outcome including serum inflammation-related parameters were examined. RESULTS- The duration of abdominal pain in the CRAI group was 1.9 =1：0.26 d, whereas that in the non-CRAI group was 4.3 ±0.50. The duration of SIRS in the CRAI group was 2.2 ± 0.22 d, whereas that in the non- CRAI group was 3.2 ± 0.28. Abdominal pain and SIRS disappeared significantly in a short period of time after the initiation of CRAI using gabexate mesilate. The average length of hospitalization significantly differed between the CRAI and non-CRAI groups, 53.3 ± 7.9 d and 87.4± 13.9 d, respectively. During the first two weeks, levels of serum CRP and the IL6/IL10 ratio in the CRAI group tended to have a rapid decrease compared to those in the non-CRAI group. CONCLUSION： The present results suggest that CRAI using gabexate mesilate was effective against SAP.
文摘The etiology of inflammatory bowel disease （IBD） has not yet been clarified and immunosuppressive agents which non-specifically reduce inflammation and immunity have been used in the conventional therapies for IBD. Evidence indicates that a dysregulation of mucosal immunity in the gut of IBD causes an overproduction of inflammatory cytokines and trafficking of effector leukocytes into the bowel, thus leading to an uncontrolled intestinal inflammation. Such recent advances in the understanding of the pathogenesis of IBD created a recent trend of novel biological therapies which specifically inhibit the molecules involved in the inflammatory cascade. Major targets for such treatment are inflammatory cytokines and their receptors, and adhesion molecules. A chimeric anti-TNF-α monoclonal antibody, infiiximab, has become a standard therapy for CD and it is also likely to be beneficial for UC. Several anti-TNF reagents have been developed but most of them seem to not be as efficacious as infliximab. A humanized anti-TNF monoclonal antibody, adalimumab may be useful for the treatment of patients who lost responsiveness or developed intolerance to infliximab. Antibodies against IL-12 p40 and IL-6 receptor could be alternative new anti-cytokine therapies for IBD. Antiinterferon-γ and anti-CD25 therapies were developed, but the benefit of these agents has not yet been established. The selective blocking of migration of leukocytes into intestine seems to be a nice approach. Antibodies against α4 integrin and α4β7 integrin showed benefit for IBD. Antisense oligonucleotide of intercellular adhesion molecule 1 （ICAM-1） may be efficacious for IBD. Clinical trials of such compounds have been either recently reported or are currently underway. In this article, we review the efficacy and safety of such novel biological therapies for IBD.
基金Supported by Research Center for Innovative Cancer Therapy,Cancer Vaccine Development Division,Kurume University to Matsueda Sin part by the Office of Research and Development Medical Research Service Department of Veterans Affairs,Public Health Service grants DK067366 and DK56338 which funds the Texas Medical Center Digestive Diseases Center to Graham DY
文摘Gastric cancer is the second most common of cancerrelated deaths worldwide.In the majority of cases gastric cancer is advanced at diagnosis and although medical and surgical treatments have improved,survival rates remain poor.Cancer immunotherapy has emerged as a powerful and promising clinical approach for treatment of cancer and has shown major success in breast cancer,prostate cancer and melanoma.Here,we provide an overview of concepts of modern cancer immunotherapy including the theory,current approaches,remaining hurdles to be overcome,and the future prospect of cancer immunotherapy in the treatment of gastric cancer.Adaptive cell therapies,cancer vaccines,gene therapies,monoclonal antibody therapies have all been used with some initial successes in gastric cancer.However,to date the results in gastric cancer have been disappointing as current approaches often do not stimulate immunity efficiently allowing tumors continue to grow despite the presence of a measurable immune response.Here,we discuss the identification of targets for immunotherapy and the role of biomarkers in prospectively identifying appropriate subjects or immunotherapy.We also discuss the molecular mechanisms by which tumor cells escape host immunosurveillance and produce an immunosuppressive tumor microenvironment.We show how advances have provided tools for overcoming the mechanisms of immunosuppression including the use of monoclonal antibodies to block negative regulators normally expressed on the surface of T cells which limit activation and proliferation of cytotoxic T cells.Immunotherapy has greatly improved and is becoming an important factor in such fields as medical care and welfare for human being.Progress has been rapid ensuring that the future of immunotherapy for gastric cancer is bright.
基金Supported by Grant-in-Aid for Young Scientists,Ministry of Education,Culture,Sports,Science and Technology of Japan,No.24791434(to Hayashi H)and Takeda Science Foundation,Japan(to Hayashi H)
文摘Thrombocytopenia is a common complication in liver disease and can adversely affect the treatment of liver cirrhosis,limiting the ability to administer therapy and delaying planned surgical/diagnostic procedures because of an increased risk of bleeding.Multiple factors,including splenic sequestration,reduced activity of the hematopoietic growth factor thrombopoietin,bone marrow suppression by chronic hepatitis C virus infection and anti-cancer agents,and antiviral treatment with interferon-based therapy,can contribute to the development of thrombocytopenia in cirrhotic patients.Of these factors,the major mechanisms for thrombocytopenia in liver cirrhosis are(1)platelet sequestration in the spleen;and(2)decreased production of thrombopoietin in the liver.Several treatment options,including platelet transfusion,interventional partial splenic embolization,and surgical splenectomy,are now available for severe thrombocytopenia in cirrhotic patients.Although thrombopoietin agonists and targeted agents are alternative tools for noninvasively treating thrombocytopenia due to liver cirrhosis,their ability to improve thrombocytopenia in cirrhotic patients is under investigation in clinical trials.In this review,we propose a treatment approach to thrombocytopenia according to our novel concept of splenic volume,and we describe the current management of thrombocytopenia due to liver cirrhosis.
文摘Molecular mechanisms of hybrid breakdown associated with sterility (F<sub>2</sub> sterility) are poorly understood as compared with those of F<sub>1</sub> hybrid sterility. Previously, we characterized three unlinked epistatic loci, hybrid sterility-a1 (hsa1), hsa2, and hsa3, responsible for the F<sub>2</sub> sterility in a cross between Oryza sativa ssp. indica and japonica. In this study, we identified that the hsa1 locus contains two interacting genes, HSA1a and HSA1b, within a 30-kb region. HSA1a-j (japonica allele) encodes a highly conserved plant-specific domain of unknown function protein (DUF1618), whereasthe indica allele (HSA1a-i<sup>s</sup>) has two deletion mutations that cause disruption of domain structure. The second gene, HSA1b-i<sup>s</sup>, encodes an uncharacterized proteinwith some similarity to a nucleotide-binding protein. Homozygous introgression of indica HSA1a-i<sup>s</sup>-HSA1b-i<sup>s</sup> alleles into japonica showed female gamete abortion at an early mitotic stage. The fact that the recombinant haplotype HSA1a-j-HSA1b-i<sup>s</sup> caused semi-sterility in the heterozygous state with the HSA1a-i<sup>s</sup>-HSA1b-i<sup>s</sup> haplotype suggests that variation in the hsa1 locus is a possible cause of the wide-spectrum sterility barriers seen in F<sub>1</sub> hybrids and successive generations in rice. We propose a simple genetic model to explain how a single causal mechanism can drive both F<sub>1</sub> and F<sub>2</sub> hybrid sterility.
文摘AIM: To elucidate the immunologic parameters for the outcome of patients with malignant tumors, especially esophageal squamous cell carcinoma (ESCC) associated with high malignant potential. METHODS: Clinicopathologic features were compared between patients with lower and higher CD4 and CD8 values as well as CD4/CD8 ratio in peripheral blood. RESULTS: The survival rate of patients with higher CD4 value was significantly better than that in patients with lower CD4 value (P = 0.039). The survival rate of patients with higher CD8 value was significantly worse than that of patients with lower CD8 value (P = 0.026). Similarly, the survival rate of patients with higher CD4/ CD8 ratio was significantly better than that of patients with lower CD4/CD8 ratio (P = 0.042). Additionally, multivariate analysis demonstrated that lower CD8 and lower CD4/CD8 ratio were factors independently associated with worse prognosis of patients. CONCLUSION: All the immunologic parameters can predict the outcome of patients with ESCC.
文摘AIM:To assess the clinicopathologic characteristics,risk factors,and prognosis for synchronous multiple early gastric cancer(SMGC).METHODS:A total of 146 patients with SMGC and1194 patients with single gastric cancer who had undergone gastrectomy between 1989 and 2008 were retrospectively analyzed to determine their clinicopathologic characteristics and postoperative survival.Tumors were classified into groups on the basis of location and histology.Smoking habits were evaluated using the Brinkman index.Clinical and pathological factors were compared using either Fisher’s exact test or Pearson’sχ2test.Logistic regression analysis was performed to identify independent risk factors.Survival rate was calculated using the Kaplan-Meier method.RESULTS:SMGCs accounted for 10.9%of gastric cancer cases and occurred predominantly in elderly male patients with a family history of gastric cancer who were both smokers and drinkers.These tumors were typically macroscopically elevated and histologically differentiated.There were no significant differences between SMGC and single gastric cancer patients with respect to tumor location,tumor size,lymph node metastasis,the number of metastatic lymph nodes,venous invasion,or tumor stage(P=0.052,P=0.347,P=0.595,P=0.805,P=0.559,and P=0.408,respectively).Further,there was no significant difference in postoperative survival between the patient groups(P=0.200).Of the 146SMGC patients,a single patient had remnant cancer.CONCLUSION:A careful preoperative endoscopy is necessary for patients who are at high risk of SMGC,and minimally invasive treatment may be indicated in some cases.
基金Supported by The Japan Society for the Promotion of Science,Kakenhi Grant,No.24390303
文摘Pancreatic cancer is one of the most aggressive and difficult cancers to treat.Despite numerous research efforts,limited success has been achieved in the therapeutic management of patients with this disease.In the current review,we focus on one component of morphogenesis signaling,Hedgehog(Hh),with the aim of developing novel,effective therapies for the treatment of pancreatic cancer.Hh signaling contributes to the induction of a malignant phenotype in pancreatic cancer and is responsible for maintaining pancreatic cancer stem cells.In addition,we propose a novel concept linking Hh signaling and tumor hypoxic conditions,and discuss the effects of Hh inhibitors in clinical trials.The Hh signaling pathway may represent a potential therapeutic target for patients with refractory pancreatic cancer.
基金This paper is funded by the higher ministry of education in Egypt.
文摘This paper presents a coordination strategy of Load Frequency Control(LFC)and digital frequency protection for an islanded microgrid(MG)considering high penetration of Renewable Energy Sources(RESs).In such MGs,the reduction in system inertia due to integration of large amount of RESs causes undesirable influence on MG frequency stability,leading to weakening of the MG.Furthermore,sudden load events,and short circuits caused large frequency fluctuations,which threaten the system security and could lead to complete blackouts as well as damages to the system equipment.Therefore,maintaining the dynamic security in MGs is one of the important challenges,which considered in this paper using a specific design and various data conversion stages of a digital over/under frequency relay(OUFR).The proposed relay will cover both under and over frequency conditions in coordination with LFC operation to protect the MG against high frequency variations.To prove the response of the proposed coordination strategy,a small MG was investigated for the simulation.The proposed coordination method has been tested considering load change,high integration of RESs.Moreover,the sensitivity analysis of the presented technique was examined by varying the penetration level of RESs and reducing the system inertia.The results reveal the effectiveness of the proposed coordination to maintain the power system frequency stability and security.In addition,the superiority of the OUFR has been approved in terms of accuracy and speed response during high disturbances.
文摘An application of contra-rotating rotors has been proposed against a demand for developing higher specific speed axial flow pump. In the present paper, the advantage and disadvantage of using contra-rotating rotors are described in comparison with conventional type of rotor-stator, based on theoretical and experimental investigations. The advantages are as follows： （1） The pump is inherently designed as smaller sized and at lower rotational speed. （2） A stable head-characteristic curve for flow rate with negative slope appears. （3） As the rear rotor rotational speed is varied as independent control of front rotor, the wider range of high performance operation is obtained by rear rotor speed control in addition to front rotor speed control. The disadvantages are as follows： （1） The structure of double shaft system becomes complex. （2） The pump performance is inferior at over flow rate as the rear rotor loading is weakened. （3） The blade rows interaction from rear rotor to front rotor more strongly appears. Then the rear rotor design is a key to achieve higher pump performance. Some methods to overcome these disadvantages will be discussed in more details toward wider usage of contra-rotating axial flow pump in various industrial fields.
