In the present study,AZ31 magnesium alloy sheets were processed by friction stir processing(FSP)to investigate the effect of the grain refinement and grain size distribution on the corrosion behavior.Grain refinement ...In the present study,AZ31 magnesium alloy sheets were processed by friction stir processing(FSP)to investigate the effect of the grain refinement and grain size distribution on the corrosion behavior.Grain refinement from a starting size of 16.4±6.8µm to 3.2±1.2µm was attained after FSP.Remarkably,bimodal grain size distribution was observed in the nugget zone with a combination of coarse(11.62±8.4µm)and fine grains(3.2±1.2µm).Due to the grain refinement,a slight improvement in the hardness was found in the nugget zone of FSPed AZ31.The bimodal grain size distribution in the stir zone showed pronounced influence on the corrosion rate of FSPed AZ31 as observed from the immersion and electrochemical tests.From the X-ray diffraction analysis,more amount of Mg(OH)_(2) was observed on FSPed AZ31 compared with the unprocessed AZ31.Polarization measurements demonstrated the higher corrosion current density for FSPed AZ31(8.92×10^(−5)A/cm^(2))compared with the unprocessed condition(2.90×10^(−5)A/cm^(2))that can be attributed to the texture effect and large variations in the grain size which led to non-uniform galvanic intensities.展开更多
Titanium alloys have been successfully applied for aerospace, ship and chemical industries because they possess many good characteristics such as high specific strength, superior corrosion resistance and excellent hig...Titanium alloys have been successfully applied for aerospace, ship and chemical industries because they possess many good characteristics such as high specific strength, superior corrosion resistance and excellent high temperature resistance. Though these alloys show reasonable weldability characteristics, the joint properties are greatly influenced by the welding processes. Weld thermal cycle of the processes will control the weld metal solidification and subsequent phase transformation and resultant microstructure. The welded joints of Ti-6Al-4V alloy were fabricated by gas tungsten arc welding （GTAW）, laser beam welding （LBW） and electron beam welding （EBW） processes. The joints fabricated by EBW process exhibit higher strength compared with the GTAW and LBW joints; but the joints by GTAW process exhibit higher impact toughness compared with the LBW and EBW joints. The resultant tensile and impact properties of the welded joints were correlated with the weld metal microstructures.展开更多
AIM: To evaluate the association of known copy number variations(CNVs) in ulcerative colitis(UC) progressing to colorectal cancer.METHODS: Microsatellite instability analysis using the National Cancer Institute's ...AIM: To evaluate the association of known copy number variations(CNVs) in ulcerative colitis(UC) progressing to colorectal cancer.METHODS: Microsatellite instability analysis using the National Cancer Institute's panel of markers, and CNV association studies using Agilent 2 × 105 k arrays were done in tissue samples from four patient groups with UC: those at low risk(LR) or high risk of developing colorectal cancer, those with premalignant dysplastic lesions, and those with colitis-associated colorectal cancer(CAC). DNA from tissue samples of these groups were independently hybridized on arrays and analyzed. The data obtained were further subjected to downstream bioinformatics enrichment analysis to examine the correlation with CAC progression.RESULTS: Microarray analysis highlighted a progressive increase in the total number of CNVs [LR(n = 178) vs CAC(n = 958), 5.3-fold], gains and losses [LR(n = 37 and 141) vs CAC(n = 495 and 463), 13.4- and 3.3-fold, respectively], size [LR(964.2 kb) vs CAC(10540 kb), 10.9-fold] and the number of genes in such regions [LR(n = 119) vs CAC(n = 455), 3.8-fold]. Chromosomewise analysis of CNVs also showed an increase in the number of CNVs across each chromosome. There were 38 genes common to all four groups in the study; 13 of these were common to cancer genes from the Genetic Disease Association dataset. The gene set enrichment analysis and ontology analysis highlighted many cancerassociated genes. All the samples in the different groupswere microsatellite stable.CONCLUSION: Increasing numbers of CNVs are associated with the progression of UC to CAC, and warrant further detailed exploration.展开更多
The liver is the commonest site of metastatic disease for patients with colorectal cancer,with at least 25%developing colorectal liver metastases(CRLM)during the course of their illness.The management of CRLM has evol...The liver is the commonest site of metastatic disease for patients with colorectal cancer,with at least 25%developing colorectal liver metastases(CRLM)during the course of their illness.The management of CRLM has evolved into a complex field requiring input from experienced members of a multi-disciplinary team involving radiology(cross sectional,nuclear medicine and interventional),Oncology,Liver surgery,Colorectal surgery,and Histopathology.Patient management is based on assessment of sophisticated clinical,radiological and biomarker information.Despite incomplete evidence in this very heterogeneous patient group,maximising resection of CRLM using all available techniques remains a key objective and provides the best chance of long-term survival and cure.To this end,liver resection is maximised by the use of downsizing chemotherapy,optimisation of liver remnant by portal vein embolization,associating liver partition and portal vein ligation for staged hepatectomy,and combining resection with ablation,in the context of improvements in the functional assessment of the future remnant liver.Liver resection may safely be carried out laparoscopically or open,and synchronously with,or before,colorectal surgery in selected patients.For unresectable patients,treatment options including systemic chemotherapy,targeted biological agents,intraarterial infusion or bead delivered chemotherapy,tumour ablation,stereotactic radiotherapy,and selective internal radiotherapy contribute to improve survival and may convert initially unresectable patients to operability.Currently evolving areas include biomarker characterisation of tumours,the development of novel systemic agents targeting specific oncogenic pathways,and the potential reemergence of radical surgical options such as liver transplantation.展开更多
Friction stir processing(FSP)is a novel solid state technique to synthesize metal matrix composites.In the present work,an attempt has been made to synthesize AZ31/TiC magnesium matrix composites using FSP and to anal...Friction stir processing(FSP)is a novel solid state technique to synthesize metal matrix composites.In the present work,an attempt has been made to synthesize AZ31/TiC magnesium matrix composites using FSP and to analyze the microstructure using scanning electron microscopy.A groove was prepared on 6 mm thick AZ31 magnesium alloy plates and compacted with TiC particles.The width of the groove was varied to result in four different volume fraction of TiC particles(0,6,12 and 18 vol.%).A single pass FSP was carried out using a tool rotational speed of 1200 rpm,traverse speed of 40 mm/min and an axial force of 10 kN.Scanning electron microscopy was employed to study the microstructure of the synthesized composites.The results indicated that TiC particles were distributed uniformly in the magnesium matrix without the formation of clusters.There was no interfacial reaction between the magnesium matrix and the TiC particle.TiC particles were properly bonded to the magnesium matrix.展开更多
BACKGROUND: Acute pancreatitis remains a common presentation to acute surgical units and carries significant morbidity and mortality. The progression of the disease to necrotizing pancreatitis and multi-organ dysfunct...BACKGROUND: Acute pancreatitis remains a common presentation to acute surgical units and carries significant morbidity and mortality. The progression of the disease to necrotizing pancreatitis and multi-organ dysfunction syndrome (MODS) is associated with a very poor clinical outcome, and persistendy high mortality. Increases in serum endothelin (ET) have been seen in animal models of acute pancreatitis and this study aims to investigate whether there is a change in serum ET-1 in patients with acute pancreatitis and whether any such change is linked to disease severity. METHODS: All patients admitted with acute pancreatitis were prospectively recruited from die emergency admissions at the Norfolk and Norwich University Hospital. Serum ET levels were determined on admission, at 24 hours and 5 days post admission. Healthy adult controls were recruited from dermatology outpatients. RESULTS: A total of 21 patients joined the trial after giving informed consent. There were 3 men and 18 women with a median age of 65 years (range 26-87 years). Serum ET levels were significantly higher in acute pancreatitis patients than in normal controls (P <0. 05). An association was seen between persistendy raised serum ET levels and progression to MODS. CONCLUSIONS: The study does demonstrate a correlation between the circulating levels of ET and acute pancreatitis in humans, although it does not elicit its involvement in the pathogenesis of the disease. The observation that a persistendy high level of circulating ET-1 is associated with progression to MODS may indicate a role for ET in the monitoring of acute pancreatitis patients for recovery or progression to MODS.展开更多
In recent times,the use of vertical take-off and landing(VTOL)multi-rotor Unmanned Aerial Vehicle(UAVs)for spraying chemical pesticides against weeds and pests has recently become popular.The current aerial spray appl...In recent times,the use of vertical take-off and landing(VTOL)multi-rotor Unmanned Aerial Vehicle(UAVs)for spraying chemical pesticides against weeds and pests has recently become popular.The current aerial spray application research is primarily focused on examining the influence of UAV spraying parameters such as flight height,travel speed,rotor configuration,droplet size,payload and wind velocity.The downwash airflow velocity generated by the UAV rotor propeller has a significant impact on the droplet deposition process.A test rig was developed to measure the downwash airflow pattern generated by the rotor propeller of a UAV.In this investigation,a six-rotor electric autonomous UAV sprayer was used to investigate the parameters and distribution laws of downwash airflow velocity.The downwash airflow velocity was measured using portable anemometers mounted on the test rig at radial positions viz.,0 m,0.5 m,1 m,1.5 m and 2 m,perpendicular to(X)and parallel to the UAV’s flight direction(Y).The experiment was conducted at three levels of hover height,viz.,1 m,2 m and 3 m(Z)and three levels of payload,viz.,0 kg,5 kg,and 10 kg.The special downwash airflow distribution pattern was analysed using the Python programming language(Version 3.7).Results show that the downwash airflow velocity generated by the radial position of the UAV rotor is evenly distributed on the rotating loop and the standard deviation of the downwash airflow velocity is less than 0.5 m/s.The maximum downwash airflow velocity of 13.8 m/s was observed below the rotor at 10 kg payload capacity,1 m hover height(Z),and 0.5 m in the X-direction.The minimum downwash wind field of 0.3 m/s was observed at 0 kg pay load capacity,1 m height,and 2 m in the X-direction.The downwash airflow velocity along each position in the radial direction of the rotor increases initially and then decreases.This downwash airflow distribution results helps in mounting of spray nozzle configuration to drone sprayer which helps to understanding spray liquid distribution and ot展开更多
Maximum Power Point Tracking(MPPT)is crucial for maximizing the energy output of photovoltaic(PV)systems by continuously adjusting the operating point of the panels to track the point of maximum power production under...Maximum Power Point Tracking(MPPT)is crucial for maximizing the energy output of photovoltaic(PV)systems by continuously adjusting the operating point of the panels to track the point of maximum power production under changing environmental conditions.This work proposes the design of an MPPT system for solar PV installations using the Differential Grey Wolf Optimizer(DGWO).It dynamically adjusts the parameters of the MPPT controller,specifically the duty cycle of the SEPIC converter,to efficiently track the Maximum Power Point(MPP).The proposed system aims to enhance the energy harvesting capability of solar PV systems by optimizing their performance under varying solar irradiance,temperature and shading conditions.Simulation results demonstrate the effectiveness of the DGWO-based MPPT system in maximizing the power output of solar PV installations compared to conventional MPPT methods.This research contributes to the development of advanced MPPT techniques for improving the efficiency and reliability of solar energy systems.展开更多
BACKGROUND Knowledge about refractive stabilization and the accuracy of postoperative refractive error measurements are crucial for improved patient outcomes after phacoemulsification.Existing guidelines typically rec...BACKGROUND Knowledge about refractive stabilization and the accuracy of postoperative refractive error measurements are crucial for improved patient outcomes after phacoemulsification.Existing guidelines typically recommend waiting 4-6 wk before prescribing corrective lenses.Our research focused on identifying factors that influence refractive errors in the early stages of post-cataract surgery,thus contributing to the existing literature on this topic.AIM To investigate the time required for refraction stability after uneventful phacoemulsification surgery.METHODS We compared the variation and statistical significance of the difference in spherical,cylindrical components,and the spherical equivalent between the 1-and 6-wk follow-up period in a group of 257 eyes that underwent uneventful phacoemulsification with foldable intraocular lens implantation,all performed by a single experienced surgeon.The Wilcoxon-Signed Rank Test was utilized to assess the magnitude of the change and determine its statistical significance.The refractive stability was defined as the point at which the change in spherical equivalent was within±0.5 dioptres for two consecutive visits.RESULTS The average age of the patients was 64.9±8.9 yr.The differences observed in both the visits in spherical power(0.1±0.2),cylinder power(0.3±0.4),and spherical equivalent(0.2±0.2)were minimal and not statistically significant.The majority of eyes(93.4%)achieved refractive stability within 6 wk after the surgery.The cylindrical power differed between age groups at the 6th wk post-operative and the difference was statistically significant(P value 0.013).There were no significant differences in refractive stability when considering sex and axial length.CONCLUSION Phacoemulsification with foldable intraocular lens implantation results in no significant changes in refraction for the majority of cases during the 6-wk follow-up period.Therefore,a spectacle prescription can be given at the completion of 1 wk.展开更多
AIM: To screen for the co-infection of hepatitis B (HBV) and hepatitis C virus (HCV) in human immunodeficiency virus (HIV) infected patients in southern India. METHODS: Five hundred consecutive HIV infected patients w...AIM: To screen for the co-infection of hepatitis B (HBV) and hepatitis C virus (HCV) in human immunodeficiency virus (HIV) infected patients in southern India. METHODS: Five hundred consecutive HIV infected patients were screened for Hepatitis B Virus (HBsAg and HBV-DNA) and Hepatitis C virus (anti-HCV and HCV-RNA) using commercially available ELISA kits; HBsAg, HBeAg/ anti-HBe (Biorad laboratories, USA) and anti-HCV (Murex Diagnostics, UK). The HBV-DNA PCR was performed to detect the surface antigen region (pre S-S). HCV-RNA was detected by RT-PCR for the detection of the constant 5' putative non-coding region of HCV. RESULTS: HBV co-infection was detected in 45/500 (9%) patients and HCV co-infection in 11/500 (2.2%) subjects. Among the 45 co-infected patients only 40 patients could be studied, where the detection rates of HBe was 55% (22/40), antiHBe was 45% (18/40) and HBV-DNA was 56% (23/40). Among 11 HCV co-infected subjects, 6 (54.5%) were anti-HCV and HCV RNA positive, while 3 (27.2%) were positive for anti-HCV alone and 2 (18%) were positive for HCV RNA alone. CONCLUSION: Since the principal routes for HIV transmission are similar to that followed by the hepatotropic viruses, as a consequence, infections with HBV and HCV are expected in HIV infected patients. Therefore, it would be advisable to screen for these viruses in all the HIV infected individuals and their sexual partners at the earliest.展开更多
Objective:To investigate the cardioprotective effect of beta-glucan against isoproterenol-induced cardiotoxicity in rats,and elucidate the underlying mechanism.Methods:Rats were orally pretreated with beta-glucan(40 m...Objective:To investigate the cardioprotective effect of beta-glucan against isoproterenol-induced cardiotoxicity in rats,and elucidate the underlying mechanism.Methods:Rats were orally pretreated with beta-glucan(40 mg/kg body weight)for 30 d,and isoproterenol(20 mg/100 g body weight)was administered on days 31 and 32.The effects of beta-glucan on markers of cardiac injury,hemodynamic changes,production of proinflammatory cytokines,and the corresponding mRNA expressions were evaluated.In addition,histological analysis was performed.Results:Pretreatment with beta-glucan prevented isoproterenol-induced cardiac injury by preserving the structural and functional integrity of the plasma membrane and attenuating the production of proinflammatory cytokines(NF-κB,TNF-α,IL-6,IL-1β,and IFN-γ)in the heart.Moreover,beta-glucan significantly downregulated the mRNA expression of ACE,AT1R,TNF-α,IL-6,NF-κB,caspase-3,TLR-4,and Bax,and upregulated Bcl-2 in the heart.At the same time,pretreatment with beta-glucan alleviated myocardial damage as reflected in a reduction in myonecrosis,edema,and erythrocyte extravasation with almost imperceptible inflammation.Conclusions:Beta-glucan can protect against isoproterenol-induced cardiotoxicity by attenuating cardiac inflammation and apoptosis and regulating the ACE-AT1R axis,thereby preventing cardiac remodeling.展开更多
Colorectal cancer accounts for a significant proportion of cancer deaths worldwide. The need to develop more chemotherapeutic agents to combat this disease is critical. Cyclin dependent kinases(CDKs), along with its b...Colorectal cancer accounts for a significant proportion of cancer deaths worldwide. The need to develop more chemotherapeutic agents to combat this disease is critical. Cyclin dependent kinases(CDKs), along with its binding partner cyclins, serve to control the growth of cells through the cell cycle. A new class of drugs, termed CDK inhibitors, has been studied in preclinical and now clinical trials. These inhibitors are believed to act as an anti-cancer drug by blocking CDKs to block the uncontrolled cellular proliferation that is hallmark of cancers like colorectal cancer. CDK article provides overview of the emerging drug class of CDK inhibitors and provides a list of ones that are currently in clinical trials.展开更多
In the present work,multi walled carbon nanotubes(MWCNT)reinforced magnesium(Mg)matrix composite was fabricated by friction stir processing(FSP)with an aim to explore its mechanical and electrochemical behavior.Micros...In the present work,multi walled carbon nanotubes(MWCNT)reinforced magnesium(Mg)matrix composite was fabricated by friction stir processing(FSP)with an aim to explore its mechanical and electrochemical behavior.Microstructural observations showed that the thickness of the produced composite layer was in the range of 2500μm.FSP resulted uniform distribution of CNT near the surface while agglomerated layers in the subsurface.Grain refinement of Mg achieved by FSP improved the hardness but significant enhancement in the hardness value was observed for FSPed MWCNT/Mg composites.Potentiodynamic polarization studies revealed that the increase in corrosion current density was observed for MWCNT/Mg composite compared with grain refined Mg and pure Mg,implying the significance of secondary phase(MWCNT)in decreasing the corrosion resistance of the composite.展开更多
A total of 79 bacteria and 101 actinobacteria strains were isolated from the sediment samples of the different points of Baratang mud volcano viz.,point of the eruption(M),middle of the volcano(MD),and the dried part ...A total of 79 bacteria and 101 actinobacteria strains were isolated from the sediment samples of the different points of Baratang mud volcano viz.,point of the eruption(M),middle of the volcano(MD),and the dried part of the mud volcano(E).Based on the biochemical and molecular characterization,the isolates were categorized under the phyla Proteobacteria,Firmicutes and Proteobacteria included representatives of Classes Alphaproteobacteria,Gammaproteobacteria and Deltaproteobacteria of 29 genera with 38 distinct ribotypes.Thirty-eight bacterial strains from four different regions of mud volcano revealed excellent activity for indole-3-acetic acid(IAA)production.Excellent antagonistic property,plant growth promoting properties such as IAA production,phosphate,potassium and zinc solubilization were identified in Bacillus megaterium NIOT_MV 31 strain of 38 studied isolates.In this study,we investigated the optimization of IAA production by B.megaterium NIOT_MV 31 and its formulation as a plant growth promoter to improve economic and agricultural development.Maximum IAA yield was achieved using optimal conditions(42.63 mg/mL)in the presence of optimized tryptophan after 4 days of incubation.Twofold increase in the plant growth parameters were observed to that of control plants.Optimization of culture conditions resulted in a fourfold increase in IAA production by B.megaterium NIOT_MV 31 cells.The results clearly demonstrated that,B.megaterium NIOT_MV 31 holds great potential as a source for IAA production and may be useful for commercial applications.展开更多
Owing to their unique design and development,high safety and low-cost efficient cathode is still at the forefront of research for rechargeable zinc-ion batteries.However,the suitable cathode operating with ultrahigh c...Owing to their unique design and development,high safety and low-cost efficient cathode is still at the forefront of research for rechargeable zinc-ion batteries.However,the suitable cathode operating with ultrahigh capacity with a dendrite-free anode reaction mechanism remains challenging.In this,the first archetype of a high-rate and morphologically stabled cathode material is constructed from novel cauliflower-like nano-ZnV_(2)S_(4)for aqueous zinc-ion batteries.Thus,nano-ZnV_(2)S_(4)was prepared with an anion exchange reaction using ZnV2(OH)8 cauliflower-like nanostructured array as a template interestingly no morphological and shape changes were detected.The as-prepared nano-ZnV_(2)S_(4)electrode reveals a specific discharge capacity of 348.2 mAh/g during 0.5 A/g with enhanced rate capability and excellent capacity retention of 89.2%at 4 A/g current density even after completing 1000 cycles.展开更多
In this work, the excess water-stagnation issue in the high current region in direct methanol fuel cells(DMFCs) is resolved by using atomic precision modulated nitrogen-crafted graphene(NG) in the cathode microporous ...In this work, the excess water-stagnation issue in the high current region in direct methanol fuel cells(DMFCs) is resolved by using atomic precision modulated nitrogen-crafted graphene(NG) in the cathode microporous layer by utilizing simplistic,industrial-expansive and ecological strategy. Few-layer 2D-graphene(~2–5 nm thickness) is prepared by bath sonication approach from abundant feedstock-graphite and is treated with nitric acid to yield 1.8 wt.% uniformly dispersed nitrogen containing NG. Specifically, 1:4 weight ratio NG:carbon-black(CB) hybrid architecture, displays 0.252 V in 370 mA cm^(-2) with the peak power density of 93.4 mW cm^(-2), improving cell power density by 45.6% compared with standard one at 60℃ and 1 mol/L methanol/oxygen conditions at ultra-low catalyst loadings and displaying exceptional stability. Atomic insights into NG reveal that interplay between bonding configurations, altered hydrophobic/hydrophilic porosity of graphene(10.6% less wettability from contact angle and 13.1% high electrode porosity measurements) contribute to the better mass-transport-porogenic effect(16.3% high oxygen-permeability), mildly affecting the electron pathway(6.5% reduced in-plane electrical conductivity),overall significantly improving cell performance. Altogether, this work delivers multiple advantages, i.e., the usage of material from facile, sustainable and cost-effective routes, while improving DMFC performance with potential industrial promise.展开更多
During the COVID-19 pandemic,several studies have shown that severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)infection is associated with a substantial reduction in the risk of subsequent reinfection with a...During the COVID-19 pandemic,several studies have shown that severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)infection is associated with a substantial reduction in the risk of subsequent reinfection with antigenically-related variants of the virus for at least 6 months[1,2].展开更多
In this study,a total of 1125 actinobacteria were isolated from the selected mangrove species:Avicennia marina,Rhizopora mucronata and Ceriops tagal from three study stations viz.,Minnie Bay,Carbyn’s Cove and Burmana...In this study,a total of 1125 actinobacteria were isolated from the selected mangrove species:Avicennia marina,Rhizopora mucronata and Ceriops tagal from three study stations viz.,Minnie Bay,Carbyn’s Cove and Burmanallah.Among these three stations,the highest number of actinobacteria was recorded in Carbyn’s Cove(64.97%),followed by(25.51%)at Burmanallah and the minimum of(9.51%)was recorded in Minnie Bay.Maximum number of actinobacteria was recorded from Ceriops tagal(40.44%)than the other selected mangrove species Avicennia marina(34.13%)and Rhizopora mucronata(25.42%).Among the 1,125 mangrove-associated actinobacteria,103 morphologically different isolates from the Minnie Bay station was selected for the further characterization studies.In antibacterial assay,30.11%of the isolates revealed inhibitory activ-ity against all tested clinical pathogens and 65%isolates displayed inhibitory activity against minimum of 04 tested clinical pathogens.Growth survival studies of the actinobacterial isolates also accomplished to withstand in varied NaCl and pH levels.Of 103 isolates,all were found to synthesize gelatinase enzyme,73 isolates demonstrated amylolytic activity,38 isolates exhibited proteolytic and 63 isolates displayed urease activity.Interestingly,56 isolates exhibited excellent DNase activity and 71 isolates revealed positive for l-asparaginase production.To our recognition,11 isolates exhibited constructive results in the production of 06 extracellular enzymes of industrial importance.Of 103 isolates,48 isolates were confirmed by molecular level identification.Based on the phylogenetic analysis,the isolates were categorized under the genera:Strep-tomyces,Nocardiopsis,Salinispora and Actinomadura.展开更多
Aeroelastic study of flight vehicles has been a subject of great interest and research in the last several years. Aileron reversal and flutter related problems are due in part to the elasticity of a typical airplane. ...Aeroelastic study of flight vehicles has been a subject of great interest and research in the last several years. Aileron reversal and flutter related problems are due in part to the elasticity of a typical airplane. Structural dynamics of an aircraft wing due to its aeroelastic nature are characterized by partial differential equations. Controller design for these systems is very complex as compared to lumped parameter systems defined by ordinary differential equations. In this paper, a stabilizing statefeedback controller design approach is presented for the heave dynamics of a wing-fuselage model. In this study, a continuous actuator in the spatial domain is assumed. A control methodology is developed by combining the technique of “proper orthogonal decomposition” and approximate dynamic programming. The proper orthogonal decomposition technique is used to obtain a low-order nonlinear lumped parameter model of the infinite dimensional system. Then a near optimal controller is designed using the single-network-adaptive-critic technique. Furthermore,to add robustness to the nominal single-network-adaptive-critic controller against matched uncertainties, an identifier based adaptive controller is proposed. Simulation results demonstrate the effectiveness of the single-network-adaptive-critic controller augmented with adaptive controller for infinite dimensional systems.展开更多
Vertical ZnO nanotube （ZNT） arrays were synthesized onto an indium doped tin oxide （ITO） glass substrate by a simple electrochemical deposition technique followed by a selective etching process. Scanning electron ...Vertical ZnO nanotube （ZNT） arrays were synthesized onto an indium doped tin oxide （ITO） glass substrate by a simple electrochemical deposition technique followed by a selective etching process. Scanning electron microscopy （SEM） showed formation of well-faceted hexagonal ZNT arrays spreading uniformly over a large area. X-ray diffraction （XRD） of ZNT layer showed substantially higher intensity for the （0002） diffraction peak, indicating that the ZnO crystallites were well aligned with their c-axis. Profilometer measurements of the ZNT layer showed an average thickness of -7 μm. Diameter size distribution （DSD） analysis showed that ZNTs exhibited a narrow diameter size distribution in the range of 65-120 nm and centered at -75 nm. The photoluminescence （PL） spectrum measurement showed violet and blue luminescence peaks that were centered at 410 and 480 nm, respectively, indicating the presence of internal defects. Ultra-violet （UV） spectroscopy showed major absorbance peak at ,-348 nm, exhibiting an increase in energy gap value of 3.4 eV. By employing the formed ZNTs as the photo-anode for a dye-sensitized solar cell （DSSC）, a full-sun conversion efficiency of 1.01% was achieved with a fill factor of 54%. Quantum efficiency studies showed the maximum of incident photon-to-electron conversion efficiency in a visible region located at 590-550 nm range.展开更多
文摘In the present study,AZ31 magnesium alloy sheets were processed by friction stir processing(FSP)to investigate the effect of the grain refinement and grain size distribution on the corrosion behavior.Grain refinement from a starting size of 16.4±6.8µm to 3.2±1.2µm was attained after FSP.Remarkably,bimodal grain size distribution was observed in the nugget zone with a combination of coarse(11.62±8.4µm)and fine grains(3.2±1.2µm).Due to the grain refinement,a slight improvement in the hardness was found in the nugget zone of FSPed AZ31.The bimodal grain size distribution in the stir zone showed pronounced influence on the corrosion rate of FSPed AZ31 as observed from the immersion and electrochemical tests.From the X-ray diffraction analysis,more amount of Mg(OH)_(2) was observed on FSPed AZ31 compared with the unprocessed AZ31.Polarization measurements demonstrated the higher corrosion current density for FSPed AZ31(8.92×10^(−5)A/cm^(2))compared with the unprocessed condition(2.90×10^(−5)A/cm^(2))that can be attributed to the texture effect and large variations in the grain size which led to non-uniform galvanic intensities.
基金the Combat Vehicle Research and Development Establishment(CVRDE),Avadi,Chennai,Government of India for providing financial support to carry out this investigation through a Contract Acquisition for Research Services project,No.CVRDE/MMG/09-10/0043/CARS
文摘Titanium alloys have been successfully applied for aerospace, ship and chemical industries because they possess many good characteristics such as high specific strength, superior corrosion resistance and excellent high temperature resistance. Though these alloys show reasonable weldability characteristics, the joint properties are greatly influenced by the welding processes. Weld thermal cycle of the processes will control the weld metal solidification and subsequent phase transformation and resultant microstructure. The welded joints of Ti-6Al-4V alloy were fabricated by gas tungsten arc welding （GTAW）, laser beam welding （LBW） and electron beam welding （EBW） processes. The joints fabricated by EBW process exhibit higher strength compared with the GTAW and LBW joints; but the joints by GTAW process exhibit higher impact toughness compared with the LBW and EBW joints. The resultant tensile and impact properties of the welded joints were correlated with the weld metal microstructures.
基金Supported by Grants from Department of Biotechnology(BT/01/COE/06/02/07)TIFAC-CORE in Pharmacogenomics,Government of India
文摘AIM: To evaluate the association of known copy number variations(CNVs) in ulcerative colitis(UC) progressing to colorectal cancer.METHODS: Microsatellite instability analysis using the National Cancer Institute's panel of markers, and CNV association studies using Agilent 2 × 105 k arrays were done in tissue samples from four patient groups with UC: those at low risk(LR) or high risk of developing colorectal cancer, those with premalignant dysplastic lesions, and those with colitis-associated colorectal cancer(CAC). DNA from tissue samples of these groups were independently hybridized on arrays and analyzed. The data obtained were further subjected to downstream bioinformatics enrichment analysis to examine the correlation with CAC progression.RESULTS: Microarray analysis highlighted a progressive increase in the total number of CNVs [LR(n = 178) vs CAC(n = 958), 5.3-fold], gains and losses [LR(n = 37 and 141) vs CAC(n = 495 and 463), 13.4- and 3.3-fold, respectively], size [LR(964.2 kb) vs CAC(10540 kb), 10.9-fold] and the number of genes in such regions [LR(n = 119) vs CAC(n = 455), 3.8-fold]. Chromosomewise analysis of CNVs also showed an increase in the number of CNVs across each chromosome. There were 38 genes common to all four groups in the study; 13 of these were common to cancer genes from the Genetic Disease Association dataset. The gene set enrichment analysis and ontology analysis highlighted many cancerassociated genes. All the samples in the different groupswere microsatellite stable.CONCLUSION: Increasing numbers of CNVs are associated with the progression of UC to CAC, and warrant further detailed exploration.
文摘The liver is the commonest site of metastatic disease for patients with colorectal cancer,with at least 25%developing colorectal liver metastases(CRLM)during the course of their illness.The management of CRLM has evolved into a complex field requiring input from experienced members of a multi-disciplinary team involving radiology(cross sectional,nuclear medicine and interventional),Oncology,Liver surgery,Colorectal surgery,and Histopathology.Patient management is based on assessment of sophisticated clinical,radiological and biomarker information.Despite incomplete evidence in this very heterogeneous patient group,maximising resection of CRLM using all available techniques remains a key objective and provides the best chance of long-term survival and cure.To this end,liver resection is maximised by the use of downsizing chemotherapy,optimisation of liver remnant by portal vein embolization,associating liver partition and portal vein ligation for staged hepatectomy,and combining resection with ablation,in the context of improvements in the functional assessment of the future remnant liver.Liver resection may safely be carried out laparoscopically or open,and synchronously with,or before,colorectal surgery in selected patients.For unresectable patients,treatment options including systemic chemotherapy,targeted biological agents,intraarterial infusion or bead delivered chemotherapy,tumour ablation,stereotactic radiotherapy,and selective internal radiotherapy contribute to improve survival and may convert initially unresectable patients to operability.Currently evolving areas include biomarker characterisation of tumours,the development of novel systemic agents targeting specific oncogenic pathways,and the potential reemergence of radical surgical options such as liver transplantation.
文摘Friction stir processing(FSP)is a novel solid state technique to synthesize metal matrix composites.In the present work,an attempt has been made to synthesize AZ31/TiC magnesium matrix composites using FSP and to analyze the microstructure using scanning electron microscopy.A groove was prepared on 6 mm thick AZ31 magnesium alloy plates and compacted with TiC particles.The width of the groove was varied to result in four different volume fraction of TiC particles(0,6,12 and 18 vol.%).A single pass FSP was carried out using a tool rotational speed of 1200 rpm,traverse speed of 40 mm/min and an axial force of 10 kN.Scanning electron microscopy was employed to study the microstructure of the synthesized composites.The results indicated that TiC particles were distributed uniformly in the magnesium matrix without the formation of clusters.There was no interfacial reaction between the magnesium matrix and the TiC particle.TiC particles were properly bonded to the magnesium matrix.
基金GI Research fund, Department of Upper GI Surgery,Norfolk and Norwich University Hospital NHS Trust.
文摘BACKGROUND: Acute pancreatitis remains a common presentation to acute surgical units and carries significant morbidity and mortality. The progression of the disease to necrotizing pancreatitis and multi-organ dysfunction syndrome (MODS) is associated with a very poor clinical outcome, and persistendy high mortality. Increases in serum endothelin (ET) have been seen in animal models of acute pancreatitis and this study aims to investigate whether there is a change in serum ET-1 in patients with acute pancreatitis and whether any such change is linked to disease severity. METHODS: All patients admitted with acute pancreatitis were prospectively recruited from die emergency admissions at the Norfolk and Norwich University Hospital. Serum ET levels were determined on admission, at 24 hours and 5 days post admission. Healthy adult controls were recruited from dermatology outpatients. RESULTS: A total of 21 patients joined the trial after giving informed consent. There were 3 men and 18 women with a median age of 65 years (range 26-87 years). Serum ET levels were significantly higher in acute pancreatitis patients than in normal controls (P <0. 05). An association was seen between persistendy raised serum ET levels and progression to MODS. CONCLUSIONS: The study does demonstrate a correlation between the circulating levels of ET and acute pancreatitis in humans, although it does not elicit its involvement in the pathogenesis of the disease. The observation that a persistendy high level of circulating ET-1 is associated with progression to MODS may indicate a role for ET in the monitoring of acute pancreatitis patients for recovery or progression to MODS.
文摘In recent times,the use of vertical take-off and landing(VTOL)multi-rotor Unmanned Aerial Vehicle(UAVs)for spraying chemical pesticides against weeds and pests has recently become popular.The current aerial spray application research is primarily focused on examining the influence of UAV spraying parameters such as flight height,travel speed,rotor configuration,droplet size,payload and wind velocity.The downwash airflow velocity generated by the UAV rotor propeller has a significant impact on the droplet deposition process.A test rig was developed to measure the downwash airflow pattern generated by the rotor propeller of a UAV.In this investigation,a six-rotor electric autonomous UAV sprayer was used to investigate the parameters and distribution laws of downwash airflow velocity.The downwash airflow velocity was measured using portable anemometers mounted on the test rig at radial positions viz.,0 m,0.5 m,1 m,1.5 m and 2 m,perpendicular to(X)and parallel to the UAV’s flight direction(Y).The experiment was conducted at three levels of hover height,viz.,1 m,2 m and 3 m(Z)and three levels of payload,viz.,0 kg,5 kg,and 10 kg.The special downwash airflow distribution pattern was analysed using the Python programming language(Version 3.7).Results show that the downwash airflow velocity generated by the radial position of the UAV rotor is evenly distributed on the rotating loop and the standard deviation of the downwash airflow velocity is less than 0.5 m/s.The maximum downwash airflow velocity of 13.8 m/s was observed below the rotor at 10 kg payload capacity,1 m hover height(Z),and 0.5 m in the X-direction.The minimum downwash wind field of 0.3 m/s was observed at 0 kg pay load capacity,1 m height,and 2 m in the X-direction.The downwash airflow velocity along each position in the radial direction of the rotor increases initially and then decreases.This downwash airflow distribution results helps in mounting of spray nozzle configuration to drone sprayer which helps to understanding spray liquid distribution and ot
文摘Maximum Power Point Tracking(MPPT)is crucial for maximizing the energy output of photovoltaic(PV)systems by continuously adjusting the operating point of the panels to track the point of maximum power production under changing environmental conditions.This work proposes the design of an MPPT system for solar PV installations using the Differential Grey Wolf Optimizer(DGWO).It dynamically adjusts the parameters of the MPPT controller,specifically the duty cycle of the SEPIC converter,to efficiently track the Maximum Power Point(MPP).The proposed system aims to enhance the energy harvesting capability of solar PV systems by optimizing their performance under varying solar irradiance,temperature and shading conditions.Simulation results demonstrate the effectiveness of the DGWO-based MPPT system in maximizing the power output of solar PV installations compared to conventional MPPT methods.This research contributes to the development of advanced MPPT techniques for improving the efficiency and reliability of solar energy systems.
文摘BACKGROUND Knowledge about refractive stabilization and the accuracy of postoperative refractive error measurements are crucial for improved patient outcomes after phacoemulsification.Existing guidelines typically recommend waiting 4-6 wk before prescribing corrective lenses.Our research focused on identifying factors that influence refractive errors in the early stages of post-cataract surgery,thus contributing to the existing literature on this topic.AIM To investigate the time required for refraction stability after uneventful phacoemulsification surgery.METHODS We compared the variation and statistical significance of the difference in spherical,cylindrical components,and the spherical equivalent between the 1-and 6-wk follow-up period in a group of 257 eyes that underwent uneventful phacoemulsification with foldable intraocular lens implantation,all performed by a single experienced surgeon.The Wilcoxon-Signed Rank Test was utilized to assess the magnitude of the change and determine its statistical significance.The refractive stability was defined as the point at which the change in spherical equivalent was within±0.5 dioptres for two consecutive visits.RESULTS The average age of the patients was 64.9±8.9 yr.The differences observed in both the visits in spherical power(0.1±0.2),cylinder power(0.3±0.4),and spherical equivalent(0.2±0.2)were minimal and not statistically significant.The majority of eyes(93.4%)achieved refractive stability within 6 wk after the surgery.The cylindrical power differed between age groups at the 6th wk post-operative and the difference was statistically significant(P value 0.013).There were no significant differences in refractive stability when considering sex and axial length.CONCLUSION Phacoemulsification with foldable intraocular lens implantation results in no significant changes in refraction for the majority of cases during the 6-wk follow-up period.Therefore,a spectacle prescription can be given at the completion of 1 wk.
文摘AIM: To screen for the co-infection of hepatitis B (HBV) and hepatitis C virus (HCV) in human immunodeficiency virus (HIV) infected patients in southern India. METHODS: Five hundred consecutive HIV infected patients were screened for Hepatitis B Virus (HBsAg and HBV-DNA) and Hepatitis C virus (anti-HCV and HCV-RNA) using commercially available ELISA kits; HBsAg, HBeAg/ anti-HBe (Biorad laboratories, USA) and anti-HCV (Murex Diagnostics, UK). The HBV-DNA PCR was performed to detect the surface antigen region (pre S-S). HCV-RNA was detected by RT-PCR for the detection of the constant 5' putative non-coding region of HCV. RESULTS: HBV co-infection was detected in 45/500 (9%) patients and HCV co-infection in 11/500 (2.2%) subjects. Among the 45 co-infected patients only 40 patients could be studied, where the detection rates of HBe was 55% (22/40), antiHBe was 45% (18/40) and HBV-DNA was 56% (23/40). Among 11 HCV co-infected subjects, 6 (54.5%) were anti-HCV and HCV RNA positive, while 3 (27.2%) were positive for anti-HCV alone and 2 (18%) were positive for HCV RNA alone. CONCLUSION: Since the principal routes for HIV transmission are similar to that followed by the hepatotropic viruses, as a consequence, infections with HBV and HCV are expected in HIV infected patients. Therefore, it would be advisable to screen for these viruses in all the HIV infected individuals and their sexual partners at the earliest.
文摘Objective:To investigate the cardioprotective effect of beta-glucan against isoproterenol-induced cardiotoxicity in rats,and elucidate the underlying mechanism.Methods:Rats were orally pretreated with beta-glucan(40 mg/kg body weight)for 30 d,and isoproterenol(20 mg/100 g body weight)was administered on days 31 and 32.The effects of beta-glucan on markers of cardiac injury,hemodynamic changes,production of proinflammatory cytokines,and the corresponding mRNA expressions were evaluated.In addition,histological analysis was performed.Results:Pretreatment with beta-glucan prevented isoproterenol-induced cardiac injury by preserving the structural and functional integrity of the plasma membrane and attenuating the production of proinflammatory cytokines(NF-κB,TNF-α,IL-6,IL-1β,and IFN-γ)in the heart.Moreover,beta-glucan significantly downregulated the mRNA expression of ACE,AT1R,TNF-α,IL-6,NF-κB,caspase-3,TLR-4,and Bax,and upregulated Bcl-2 in the heart.At the same time,pretreatment with beta-glucan alleviated myocardial damage as reflected in a reduction in myonecrosis,edema,and erythrocyte extravasation with almost imperceptible inflammation.Conclusions:Beta-glucan can protect against isoproterenol-induced cardiotoxicity by attenuating cardiac inflammation and apoptosis and regulating the ACE-AT1R axis,thereby preventing cardiac remodeling.
文摘Colorectal cancer accounts for a significant proportion of cancer deaths worldwide. The need to develop more chemotherapeutic agents to combat this disease is critical. Cyclin dependent kinases(CDKs), along with its binding partner cyclins, serve to control the growth of cells through the cell cycle. A new class of drugs, termed CDK inhibitors, has been studied in preclinical and now clinical trials. These inhibitors are believed to act as an anti-cancer drug by blocking CDKs to block the uncontrolled cellular proliferation that is hallmark of cancers like colorectal cancer. CDK article provides overview of the emerging drug class of CDK inhibitors and provides a list of ones that are currently in clinical trials.
文摘In the present work,multi walled carbon nanotubes(MWCNT)reinforced magnesium(Mg)matrix composite was fabricated by friction stir processing(FSP)with an aim to explore its mechanical and electrochemical behavior.Microstructural observations showed that the thickness of the produced composite layer was in the range of 2500μm.FSP resulted uniform distribution of CNT near the surface while agglomerated layers in the subsurface.Grain refinement of Mg achieved by FSP improved the hardness but significant enhancement in the hardness value was observed for FSPed MWCNT/Mg composites.Potentiodynamic polarization studies revealed that the increase in corrosion current density was observed for MWCNT/Mg composite compared with grain refined Mg and pure Mg,implying the significance of secondary phase(MWCNT)in decreasing the corrosion resistance of the composite.
文摘A total of 79 bacteria and 101 actinobacteria strains were isolated from the sediment samples of the different points of Baratang mud volcano viz.,point of the eruption(M),middle of the volcano(MD),and the dried part of the mud volcano(E).Based on the biochemical and molecular characterization,the isolates were categorized under the phyla Proteobacteria,Firmicutes and Proteobacteria included representatives of Classes Alphaproteobacteria,Gammaproteobacteria and Deltaproteobacteria of 29 genera with 38 distinct ribotypes.Thirty-eight bacterial strains from four different regions of mud volcano revealed excellent activity for indole-3-acetic acid(IAA)production.Excellent antagonistic property,plant growth promoting properties such as IAA production,phosphate,potassium and zinc solubilization were identified in Bacillus megaterium NIOT_MV 31 strain of 38 studied isolates.In this study,we investigated the optimization of IAA production by B.megaterium NIOT_MV 31 and its formulation as a plant growth promoter to improve economic and agricultural development.Maximum IAA yield was achieved using optimal conditions(42.63 mg/mL)in the presence of optimized tryptophan after 4 days of incubation.Twofold increase in the plant growth parameters were observed to that of control plants.Optimization of culture conditions resulted in a fourfold increase in IAA production by B.megaterium NIOT_MV 31 cells.The results clearly demonstrated that,B.megaterium NIOT_MV 31 holds great potential as a source for IAA production and may be useful for commercial applications.
基金The authors acknowledge the funding for this project through the National Nature Science Foundations of China(No.51873083)Jasmine Jiangsu Fellowship of Jiangsu Province(No.180511800007)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.SJCX20_1453).
文摘Owing to their unique design and development,high safety and low-cost efficient cathode is still at the forefront of research for rechargeable zinc-ion batteries.However,the suitable cathode operating with ultrahigh capacity with a dendrite-free anode reaction mechanism remains challenging.In this,the first archetype of a high-rate and morphologically stabled cathode material is constructed from novel cauliflower-like nano-ZnV_(2)S_(4)for aqueous zinc-ion batteries.Thus,nano-ZnV_(2)S_(4)was prepared with an anion exchange reaction using ZnV2(OH)8 cauliflower-like nanostructured array as a template interestingly no morphological and shape changes were detected.The as-prepared nano-ZnV_(2)S_(4)electrode reveals a specific discharge capacity of 348.2 mAh/g during 0.5 A/g with enhanced rate capability and excellent capacity retention of 89.2%at 4 A/g current density even after completing 1000 cycles.
基金supported by China Postdoctoral Science Foundation(Grant No.2019M661749)Six-Talent-Peaks Project in Jiangsu Province(Grant No.2016-XNY-015)+1 种基金the High-Tech Key Laboratory of Zhenjiang City(Grant No.SS2018002)Priority Academic Program Development(PAPD) of Jiangsu Higher Education Institutions。
文摘In this work, the excess water-stagnation issue in the high current region in direct methanol fuel cells(DMFCs) is resolved by using atomic precision modulated nitrogen-crafted graphene(NG) in the cathode microporous layer by utilizing simplistic,industrial-expansive and ecological strategy. Few-layer 2D-graphene(~2–5 nm thickness) is prepared by bath sonication approach from abundant feedstock-graphite and is treated with nitric acid to yield 1.8 wt.% uniformly dispersed nitrogen containing NG. Specifically, 1:4 weight ratio NG:carbon-black(CB) hybrid architecture, displays 0.252 V in 370 mA cm^(-2) with the peak power density of 93.4 mW cm^(-2), improving cell power density by 45.6% compared with standard one at 60℃ and 1 mol/L methanol/oxygen conditions at ultra-low catalyst loadings and displaying exceptional stability. Atomic insights into NG reveal that interplay between bonding configurations, altered hydrophobic/hydrophilic porosity of graphene(10.6% less wettability from contact angle and 13.1% high electrode porosity measurements) contribute to the better mass-transport-porogenic effect(16.3% high oxygen-permeability), mildly affecting the electron pathway(6.5% reduced in-plane electrical conductivity),overall significantly improving cell performance. Altogether, this work delivers multiple advantages, i.e., the usage of material from facile, sustainable and cost-effective routes, while improving DMFC performance with potential industrial promise.
文摘During the COVID-19 pandemic,several studies have shown that severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)infection is associated with a substantial reduction in the risk of subsequent reinfection with antigenically-related variants of the virus for at least 6 months[1,2].
文摘In this study,a total of 1125 actinobacteria were isolated from the selected mangrove species:Avicennia marina,Rhizopora mucronata and Ceriops tagal from three study stations viz.,Minnie Bay,Carbyn’s Cove and Burmanallah.Among these three stations,the highest number of actinobacteria was recorded in Carbyn’s Cove(64.97%),followed by(25.51%)at Burmanallah and the minimum of(9.51%)was recorded in Minnie Bay.Maximum number of actinobacteria was recorded from Ceriops tagal(40.44%)than the other selected mangrove species Avicennia marina(34.13%)and Rhizopora mucronata(25.42%).Among the 1,125 mangrove-associated actinobacteria,103 morphologically different isolates from the Minnie Bay station was selected for the further characterization studies.In antibacterial assay,30.11%of the isolates revealed inhibitory activ-ity against all tested clinical pathogens and 65%isolates displayed inhibitory activity against minimum of 04 tested clinical pathogens.Growth survival studies of the actinobacterial isolates also accomplished to withstand in varied NaCl and pH levels.Of 103 isolates,all were found to synthesize gelatinase enzyme,73 isolates demonstrated amylolytic activity,38 isolates exhibited proteolytic and 63 isolates displayed urease activity.Interestingly,56 isolates exhibited excellent DNase activity and 71 isolates revealed positive for l-asparaginase production.To our recognition,11 isolates exhibited constructive results in the production of 06 extracellular enzymes of industrial importance.Of 103 isolates,48 isolates were confirmed by molecular level identification.Based on the phylogenetic analysis,the isolates were categorized under the genera:Strep-tomyces,Nocardiopsis,Salinispora and Actinomadura.
文摘Aeroelastic study of flight vehicles has been a subject of great interest and research in the last several years. Aileron reversal and flutter related problems are due in part to the elasticity of a typical airplane. Structural dynamics of an aircraft wing due to its aeroelastic nature are characterized by partial differential equations. Controller design for these systems is very complex as compared to lumped parameter systems defined by ordinary differential equations. In this paper, a stabilizing statefeedback controller design approach is presented for the heave dynamics of a wing-fuselage model. In this study, a continuous actuator in the spatial domain is assumed. A control methodology is developed by combining the technique of “proper orthogonal decomposition” and approximate dynamic programming. The proper orthogonal decomposition technique is used to obtain a low-order nonlinear lumped parameter model of the infinite dimensional system. Then a near optimal controller is designed using the single-network-adaptive-critic technique. Furthermore,to add robustness to the nominal single-network-adaptive-critic controller against matched uncertainties, an identifier based adaptive controller is proposed. Simulation results demonstrate the effectiveness of the single-network-adaptive-critic controller augmented with adaptive controller for infinite dimensional systems.
基金Department of Science and Technology (DST), Government of India was gratefully acknowledged for their financial support under the NATAG program monitored by Dr. G. Sundararajan
文摘Vertical ZnO nanotube （ZNT） arrays were synthesized onto an indium doped tin oxide （ITO） glass substrate by a simple electrochemical deposition technique followed by a selective etching process. Scanning electron microscopy （SEM） showed formation of well-faceted hexagonal ZNT arrays spreading uniformly over a large area. X-ray diffraction （XRD） of ZNT layer showed substantially higher intensity for the （0002） diffraction peak, indicating that the ZnO crystallites were well aligned with their c-axis. Profilometer measurements of the ZNT layer showed an average thickness of -7 μm. Diameter size distribution （DSD） analysis showed that ZNTs exhibited a narrow diameter size distribution in the range of 65-120 nm and centered at -75 nm. The photoluminescence （PL） spectrum measurement showed violet and blue luminescence peaks that were centered at 410 and 480 nm, respectively, indicating the presence of internal defects. Ultra-violet （UV） spectroscopy showed major absorbance peak at ,-348 nm, exhibiting an increase in energy gap value of 3.4 eV. By employing the formed ZNTs as the photo-anode for a dye-sensitized solar cell （DSSC）, a full-sun conversion efficiency of 1.01% was achieved with a fill factor of 54%. Quantum efficiency studies showed the maximum of incident photon-to-electron conversion efficiency in a visible region located at 590-550 nm range.
