A significant amount of aluminum dross is available as a waste in foundry industries in Bangladesh. In this study, alumina was ex- tracted from aluminum dross collected from two foundry industries situated in Dhamrai ...A significant amount of aluminum dross is available as a waste in foundry industries in Bangladesh. In this study, alumina was ex- tracted from aluminum dross collected from two foundry industries situated in Dhamrai and Manikgang, near the capital city, Dhaka. Alu- minum dross samples were found to approximately contain 75wt% A1203 and 12wt% SIO2. An acid dissolution process was used to recover the alumina value from the dross. The effects of various parameters, e.g., temperature, acid concentration, and leaching time, on the extrac- tion of alumina were studied to optimize the dissolution process. First, AI（OH）3 was produced in the form of a gel. Calcination of the AI（OH）3 gel at 1000℃, 1200℃, and 1400℃ for 2 h produced O-AlcOa, （t~＋O）-A1203, and u-alumina powder, respectively. Thermal charac- terization of the AI（OH）3 gel was performed by thermogravimetric/differential thermal analysis （TG/DTA） and differential scanning calo- rimetry （DSC）. The phases and crystallite size of the alumina were determined by X-ray diffraction analysis. The dimensions of the alumina were found to be on the nano level. The chemical compositions of the aluminum dross and alumina were determined by X-ray fluorescence （XRF） spectroscopy. The microstructure and morphology of the alumina were studied with scanning electron microscopy. The purity of the alumina extracted in this study was found to be 99.0%. Thus, it is expected that the obtained alumina powders can be potentially utilized as biomaterials.展开更多
Calcium-based biocomposite materials have a pivotal role in the biomedical field with their diverse properties and applications in combating challenging medical problems. The study states the development and character...Calcium-based biocomposite materials have a pivotal role in the biomedical field with their diverse properties and applications in combating challenging medical problems. The study states the development and characterization of Calcium-based biocomposites: Hydroxyapatite (HAP), and PVA-Gelatin-HAP films. For the preparation of Calcium-based biocomposites, an unconventional source, the waste material calcite stone, was used as calcium raw material, and by the process of calcination, calcium oxide was synthesized. From calcium oxide, HAP was prepared by chemical precipitation method, which was later added in different proportions to PVA-Gelatin solution and finally dried to form biocomposite films. Then the different properties of PVA/Gelatin/HAP composite, for instance, chemical, mechanical, thermal, and swelling properties due to the incorporation of various proportions of HAP in PVA-Gelatin solution, were investigated. The characterization of the HAP was conducted by X-ray Diffraction Analysis, and the characterization of HAP-PVA-Gelatin composites was done by Fourier Transform Infrared Spectroscopy, Thermomechanical Analysis, Tensile test, Thermogravimetric Differential Thermal Analysis, and Swelling Test. The produced biocomposite films might have applications in orthopedic implants, drug delivery, bone tissue engineering, and wound healing.展开更多
With the modern advancement of treatment approaches in medical science, the application of biomaterials in tissue engineering provides a remarkable opportunity to overcome graft rejection as well as proper wound heali...With the modern advancement of treatment approaches in medical science, the application of biomaterials in tissue engineering provides a remarkable opportunity to overcome graft rejection as well as proper wound healing. In this study, novel hybrid films have been synthesized by incorporation of polyvinyl alcohol (PVA), gelatin, and gelatin with glycerin along with different concentrations of pre-prepared hydroxyapatite (HAP) by solution casting method at room temperature in a biosafety cabinet. Glutaraldehyde has been added as a crosslinker in this whole procedure. Fourier-transform infrared spectroscopy (FTIR), X-Ray Diffraction (XRD) have been conducted to observe and compare the structural and chemical stability of the synthesized hybrid film properties. The FTIR results and X-Ray Diffraction analyses confirmed the chemical interactions between HAP, PVA, gelatin, and glycerin have occurred. The crystallinity of HAP also remains in all the prepared hybrid film samples that are observed in XRD. It is expected that these newly synthesized hybrid films could be a better opportunity for various sectors of tissue engineering such as skin, bone, tendon, and cartilage. These synthesized hybrid films can be suitable for wound healing covering. These studies could be a new scope for long-term drug delivery directly on wound sites in diabetic gangrene foot or burn patients as well as cartilage or joint replacement therapy.展开更多
In the recent research field of bone tissue engineering, polymeric materials play an implacable role in mimes the natural behavior of hard and soft tissues. In some medical conditions such as diabetics, osteoarthritis...In the recent research field of bone tissue engineering, polymeric materials play an implacable role in mimes the natural behavior of hard and soft tissues. In some medical conditions such as diabetics, osteoarthritis, burns, or joint replacement conditions, this polymeric materials implication enhances the internal mechanical activities which result in the early recovery of disease by facilitating the wound healing process. In this study, hybrid films have been synthesized based on polyvinyl alcohol (PVA), gelatin, and gelatin with glycerin incorporated with different concentrations of pre-prepared hydroxyapatite (HAP) by solution casting method at room temperature in biosafety cabinet. Glutaraldehyde has been added as a crosslinker in this whole procedure. The mechanical property, swelling, and porosity percentage have been conducted to characterize the structural stability of the synthesized hybrid films. Porosity and swelling of samples are also represented by proper biocompatibility (>90% porosity and swelling in DDW and PBF vary between 287%~72%). Tensile strength (TS), E modulus (Young’s modulus), Elongation at maximum, and Elongation at break are observed to perceive the mechanical properties of hybrid film samples, which are compatible with mechanical properties of different tissue such as trabecular bone, articular cartilage, tendon, nerve and skin tissue. Though, biocompatibility tests both in vivo and in vitro are essential for clinical application in the future. However, the experiment carried out till now explains the true possibility of newly synthesized hybrid films for long-term drug delivery directly on wound sites for wound healing and burn dressing patients in head-neck surgery reconstruction, diabetic gangrene foot, as well as cartilage or joint replacement therapy.展开更多
Although there are many lead-free soldering alloys on the market, none of them have ideal qualities. The researchers are combining binary alloys with a variety of additional materials to create the soldering alloys’ ...Although there are many lead-free soldering alloys on the market, none of them have ideal qualities. The researchers are combining binary alloys with a variety of additional materials to create the soldering alloys’ features. The eutectic Sn-9Zn alloy is among them. This paper investigated the mechanical and electrical properties of Sn-9Zn-x (Ag, Cu, Sb);{x = 0.2, 0.4, and 0.6} lead-free solder alloys. The mechanical properties such as elastic modulus, ultimate tensile strength (UTS), yield strength (YS), and ductility were examined at the strain rates in a range from 4.17 10−3 s−1 to 208.5 10−3 s−1 at room temperature. It is found that increasing the content of the alloying elements and strain rate increases the elastic modulus, ultimate tensile strength, and yield strength while the ductility decreases. The electrical conductivity of the alloys is found to be a little smaller than that of the Sn-9Zn eutectic alloy.展开更多
The development of advanced biomaterials is crucial for addressing the increasing demand for improved medical implants and tissue engineering scaffolds. Hydroxyapatite (HAp), a naturally occurring mineral form of calc...The development of advanced biomaterials is crucial for addressing the increasing demand for improved medical implants and tissue engineering scaffolds. Hydroxyapatite (HAp), a naturally occurring mineral form of calcium apatite, is widely recognized for its excellent biocompatibility and osteoconductivity, making it an ideal candidate for bone-related applications. However, its brittleness and lack of flexibility limit its broader application in dynamic biological environments. To overcome these limitations, this study explores the synthesis of Hydroxyapatite/Alginate (HAp/Alg) nanocomposites, leveraging the biocompatibility and flexibility of alginate—a natural polysaccharide derived from brown seaweed. The HAp/Alg nanocomposites were synthesized using in situ hybridization techniques with varying alginate concentrations (10 to 40 wt%) to optimize their structural and functional properties. The motivation behind this work lies in the potential of these composites to combine the desirable properties of both HAp and alginate, resulting in a material that not only mimics the mineral composition of bone but also offers enhanced flexibility and structural integrity. A comprehensive analysis was conducted using X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Thermogravimetric Analysis/Differential Thermal Analysis (TGA/DTA), Scanning Electron Microscopy (SEM), and cytotoxicity testing to evaluate the structural, chemical, and biological properties of the composites. XRD analysis indicated a complex interaction between alginate concentration and crystal growth, with crystallite size increasing up to 10 wt% alginate before decreasing. FT-IR spectra confirmed significant biological reactivity at the composite’s surface and within the polymer matrix, suggesting strong potential for biological interactions. SEM images revealed a more uniform microstructure in HAp/Alg composites compared to pure HAp, which is likely to improve their performance in biomedical applications. TGA/DTA results demon展开更多
Composites based on jute fabrics and polypropylene was fabricated by heat-press molding technique. The mechanical properties of the composites such as tensile strength, tensile modulus, bending strength, bending modul...Composites based on jute fabrics and polypropylene was fabricated by heat-press molding technique. The mechanical properties of the composites such as tensile strength, tensile modulus, bending strength, bending modulus and impact strength were measured in dependence of fiber contents. In order to improve fiber-matrix interaction, jute fabrics were treated with aqueous solutions of K2Cr2O7 (0.005-0.05% w/v). Composite prepared with 0.02% K2Cr2O7 treated jute fabrics showed the highest values of the mechanical properties. Thermogravimetric (TG/DTG) data of PP, jute fabrics and composites showed that thermal degradation temperatures of composites shifted to higher temperature regions compared to PP or jute fabrics. Treatment of jute fabrics improved the thermal stability of the composite considerably. Scanning electron microscopic images of tensile fractured sides of untreated and treated composites illustrated that better fiber-matrix interfacial interaction occurred in treated composite. The relative tendency of water absorption of both untreated and treated composites was also explored.展开更多
Aluminum based metal matrix composites were fabricated using stir casting where silicon carbide and alumina were the reinforcements. Different types of properties (physical-density, mechanical-tensile, hardness, chemi...Aluminum based metal matrix composites were fabricated using stir casting where silicon carbide and alumina were the reinforcements. Different types of properties (physical-density, mechanical-tensile, hardness, chemical-corrosion etc.) were measured and compared with base metals/alloys. The properties were significantly varied. The highest density was obtained for pure aluminium with 5% Al<sub>2</sub>O<sub>3</sub> whereas the lowest was obtained for AA-4032 alloy. The highest hardness was obtained for AA-4032 with 5% Al<sub>2</sub>O<sub>3</sub> whereas the lowest was obtained for pure Al with 5% Al<sub>2</sub>O<sub>3</sub>. The highest strength was obtained for AA-6061 with 5% coarse SiC whereas the lowest was obtained for pure Al. The highest impact strength was obtained for AA-4032 with 5% Al<sub>2</sub>O<sub>3</sub> whereas the lowest was obtained for AA-6061. The corrosion resistance of all composites was lower than that of the base materials.展开更多
Traditional wastewater mostly contains pharmaceutical ingredients. Therefore, the wastewater must be completely free from antibiotics before its release into the environment. In the present study, photocatalytic degra...Traditional wastewater mostly contains pharmaceutical ingredients. Therefore, the wastewater must be completely free from antibiotics before its release into the environment. In the present study, photocatalytic degradation was done to investigate the removal efficiency of Oxytetracycline Dihydrate (OTC) using ZnO, ZnO/3%BaTiO<sub>3</sub> (3 BZ), ZnO/18%BaTiO<sub>3</sub> (18 BZ), ZnO/ 33%BaTiO3 (33 BZ) and ZnO/48%BaTiO<sub>3</sub> (48 BZ) under UV light. After the exposure time of 420 min, about 99.57% and 97.87% of OTC was degraded using ZnO and 3 BZ respectively. Further, increasing the amount of BaTiO<sub>3</sub> in ZnO prolongs the degradation time. Therefore, faster efficiency was found using ZnO nanoparticles. The observed reaction rate constant using ZnO was 0.00933 min<sup>-1</sup> which decreased to 0.00532 min<sup>-1</sup> using 48 BZ, indicating the decrease of reaction rate for increasing the amount of BaTiO<sub>3</sub>. Hence, the use of ZnO photocatalyst is anticipated to be a promising technique for the photocatalytic degradation of contaminated wastewater with oxytetracycline antibiotics using UV light.展开更多
The tensile properties of Sn-9Zn-xAg-ySb;{(x, y) = (0.2, 0.6), (0.2, 0.8), (0.6, 0.2), (0.8, 0.2)} lead-free solders were investigated. All the test samples were annealed at 150°C for 1 hour. The tests are carrie...The tensile properties of Sn-9Zn-xAg-ySb;{(x, y) = (0.2, 0.6), (0.2, 0.8), (0.6, 0.2), (0.8, 0.2)} lead-free solders were investigated. All the test samples were annealed at 150°C for 1 hour. The tests are carried out at room temperature at the strain rate of 4.17 × 10<sup>-3</sup> s<sup>-1</sup>, 20.85 × 10<sup>-3</sup> s<sup>-1</sup>, and 208.5 × 10<sup>-3</sup> s<sup>-1</sup>. It is seen that the tensile strength increases and the ductility decrease with increasing the strain rate over the investigated range. From the strain rate change test results, the strain sensitivity values are found in the range of 0.0831 to 0.1455 due to the addition of different alloying elements.展开更多
Zirconia toughened alumina (ZTA) ceramics are very promising materials for structural and biomedical applications due to their high hardness, fracture toughness, strength, corrosion and abrasion resistance and excelle...Zirconia toughened alumina (ZTA) ceramics are very promising materials for structural and biomedical applications due to their high hardness, fracture toughness, strength, corrosion and abrasion resistance and excellent biocompatibility. The effect of unstabilized ZrO<sub>2</sub> on the density, fracture toughness, microhardness, flexural strength and microstructure of some Zirconia-toughened alumina (ZTA) samples was investigated in this work. The volume percentage of unstabilized ZrO<sub>2</sub> was varied from 0% - 20% whereas sintering time and sintering temperature were kept constant at 2 hours and 1580°C. The samples were fabricated from nanometer-sized (<em>α</em>-Al<sub>2</sub>O<sub>3</sub>: 150 nm, monoclinic ZrO<sub>2</sub>: 30 - 60 nm) powder raw materials by the conventional mechanical mixing process. Using a small amount of sintering aid (0.2 wt% MgO) almost 99.2% of theoretical density, 8.54 MPam<sup>?</sup> fracture toughness, 17.35 GPa Vickers microhardness and 495.67 MPa flexural strength were found. It was observed that the maximum flexural strength and fracture toughness was obtained for 10 vol% monoclinic ZrO<sub>2</sub> but maximum Vickers microhardness was achieved for 5 vol% ZrO<sub>2</sub> although the maximum density was found for 20 vol% ZrO<sub>2</sub>. It is assumed that this was happened due to addition of denser component, phase transformation of monoclinic ZrO<sub>2</sub> and the changes of grain size of α-Al<sub>2</sub>O<sub>3</sub> and ZrO<sub>2</sub>.展开更多
In the textile industry, cotton is the most popular choice among all the natural fibers due to its unique properties such as softness, affinity to skin, biodegradability, absorbency, and moisture being comfortable to ...In the textile industry, cotton is the most popular choice among all the natural fibers due to its unique properties such as softness, affinity to skin, biodegradability, absorbency, and moisture being comfortable to wear. Zinc Oxide Nanoparticles (ZnO NPs) were produced and coated on cotton fabrics. The concentration of Zinc acetate was varied. 2-methoxy-ethanol has been used as a solvent. Using the dip coating technique, ZnO NPs have been coated on the cotton fabric in different mole concentrations. Scanning Electron Microscopy (SEM), Ultraviolet Visible (UV-VIS) spectroscopy, the antifungal and antibacterial activity of the ZnO NPs was performed on the coated fabrics. The SEM images depicted that the nanoparticles are well dispersed on the fabric at 3M concentration of ZnO solution. It was found that the UV absorbance increases with the increase of concentration up to 2M concentration and after that it decreases. It was also found that maximum antibacterial and antifungal activity is at 2M concentration.展开更多
The sawdust reinforced Acrylonitrile Butadiene Styrene (ABS) composites were prepared by using hot press molding machine for five different wt% (0%, 5%, 10%, 15% and 20%) at 180<span style="white-space:nowrap;...The sawdust reinforced Acrylonitrile Butadiene Styrene (ABS) composites were prepared by using hot press molding machine for five different wt% (0%, 5%, 10%, 15% and 20%) at 180<span style="white-space:nowrap;">°</span>C temperature and 50 KN load. Sawdust was collected from local saw mill of Savar, Dhaka, Bangladesh and ABS polymer was collected from local market of Dhaka, Bangladesh. In this study, different properties of composites like physical (bulk density and water absorption), mechanical (tensile properties and hardness) and structural (Fourier Transform Infrared Spectroscopy) properties were studied. The bulk density of composites was not altered consistently and it gave greater value for 5% and 20% composites. The water absorption enhanced for all composites with the accumulation of fiber content and soaking time. The reduction of tensile strength and Leeb’s rebound hardness of the composites were observed with the increase of the fiber content in all compositions. Maximum (%) of elongation was found for 5% composite, and then it gradually decreased;however, elastic modulus increased with the increased of fiber content in composites. Fourier Transform Infrared (FTIR) spectroscopy study was done for structural characterization. It was found that there was a new bond (C≡C) stretching formed for 20% composite;moreover, C-H rocking for 0% composite was broken for all other composites after the addition of sawdust in ABS polymer matrix.展开更多
One-band effective mass model is used to simulation of electron gas properties in quantum well. We calculate of dispersion curves for first three subbands. Calculation results of Fermi energy, effective mass at Fermi ...One-band effective mass model is used to simulation of electron gas properties in quantum well. We calculate of dispersion curves for first three subbands. Calculation results of Fermi energy, effective mass at Fermi level as function of electron concentration are presented. The obtained results are good agreement with the experimental dates.展开更多
Influence of recombination centers’ changes on the form of phase portraits has been studied. It has been shown that the shape of the phase portraits depends on the concentration of semiconductor materials’ recombina...Influence of recombination centers’ changes on the form of phase portraits has been studied. It has been shown that the shape of the phase portraits depends on the concentration of semiconductor materials’ recombination centers.展开更多
Fiber Reinforced Thermoplastic (FRTP) composites are emerging as potential materials in many engineering fields. In this research, the compression-molding process was used as the fabrication technique for producing ta...Fiber Reinforced Thermoplastic (FRTP) composites are emerging as potential materials in many engineering fields. In this research, the compression-molding process was used as the fabrication technique for producing talc-filled reinforced polyester composite. The weight percentage of these composites was varied, like 30 wt%, 40 wt%, 45 wt%, and 50 wt% talc, respectively. Besides, different percentages of styrene monomer, such as 0 wt%, 20 wt%, and 30 wt%, were also used in this study. Different types of physical, chemical, mechanical, and thermal properties were investigated. The water absorption percentage is increased for composites having a higher percentage of talc filler, while the elasticity of the composites shows a decreasing nature with the increase of talc content. Compressive strength is increased with higher talc content. After a certain limit, with the increase of talc content, it decreases and remains more or less constant. The flexural properties (flexural strength, tangent modulus, and flexural strain) of polyester-talc composites are higher initially, and as the percentage of talc increases, the flexural properties decrease or remain constant. The rate of water absorption is very low with the increase in soaking time. The thermal analysis of polyester-talc composites shows that the thermal stability of the composites is better than that of polyester.展开更多
Tin oxide (SnO<sub>2</sub>) thin films were deposited on glass substrate by Chemical Bath Deposition (CBD), Drop-Cast and Dip-Coating method. The thin films were post-annealed at 500°C for 2 hours....Tin oxide (SnO<sub>2</sub>) thin films were deposited on glass substrate by Chemical Bath Deposition (CBD), Drop-Cast and Dip-Coating method. The thin films were post-annealed at 500°C for 2 hours. The structural, optical, and electrical properties of the SnO<sub>2</sub> thin films were investigated by using XRD, FTIR, SEM, EDX, UV-Vis spectroscopy, and Electrometer experiment. The XRD patterns of SnO<sub>2</sub> thin films deposited on glass substrate by CBD method, Drop-Cast method and Dip-Coating method showed cubic, tetragonal and amorphous structures respectively. The FTIR spectrum exhibited the strong presence of SnO<sub>2</sub> with the characteristic vibrational mode of Sn-O-Sn. The SEM analysis was observed that the surface morphology of the thin films toughly depends on the deposition methods of the SnO<sub>2</sub> thin films. EDX measurement confirmed that the thin films are the composition of Tin (Sn) and Oxygen (O<sub>2</sub>). The optical band gap of SnO<sub>2 </sub>thin films deposited by CBD method, Drop-Cast method and Dip-Coating method is found to be 3.12 eV, 3.14 eV and 3.16 eV respectively. Thin films deposited by Dip-Coating method showed the highest band gap. The electrical results confirmed that the SnO<sub>2</sub> thin films are good conductors and pursued Ohm’s Law. These properties of the SnO<sub>2</sub> thin films brand are appropriate for application in solar cell assembly, gas sensor devices and transparent electrodes of panel displays.展开更多
In this research work, (Bi<sub>2</sub>O<sub>3</sub>Fe<sub>2</sub>O<sub>3</sub>)<sub>0.4</sub>(Nb<sub>2</sub>O<sub>5</sub>)<sub>...In this research work, (Bi<sub>2</sub>O<sub>3</sub>Fe<sub>2</sub>O<sub>3</sub>)<sub>0.4</sub>(Nb<sub>2</sub>O<sub>5</sub>)<sub>0.6</sub> was made by the solid state reaction method. Samples were sintered at four different temperatures (850°C, 925°C, 1000°C and 1150°C) to study the effect of sintering temperature on the various properties of the samples. X-ray diffraction analysis confirmed that single phase Bi<sub>1.721</sub>δ<sub>0.089</sub>Fe<sub>1.056</sub>Nb<sub>1.134</sub>O<sub>7</sub> was found when sintering temperature increased. At the same time, larger grain size was found when sintering temperature increased. From variation of dielectric loss with respect to frequency, a small peak was found when sample was sintered at higher temperature (1150°C). Dielectric constant of the sample decreases with the increase of frequency for all the samples. With the variation of temperature, DC resistivity of the samples showed that resistivity decreases with the increase of measuring temperature which indicates semiconducting nature.展开更多
Fiber-reinforced polymer (FRP) composites have gradually gained wide acceptance as engineering material applications due to their unique advantages including their high strength-to-weight ratio and excellent corrosion...Fiber-reinforced polymer (FRP) composites have gradually gained wide acceptance as engineering material applications due to their unique advantages including their high strength-to-weight ratio and excellent corrosion resistance. This study was carried out with composites prepared by hot press molding method using coconut spathe fiber as reinforcing material and HDPE (from HDPE can as obsolete polymer) as polymer matrix. Composites were made at 150°C under 60 kN load by taking diverse weight percentage (wt.%) of fiber from 0 to 20 of its total weight. In this research investigation, different properties of the composites such as bulk density, water absorption, tensile and flexural properties, impact strength and hardness test properties were carried out. The fiber content enhancement increases the bulk density in all composites. The rate of water absorption improves with the improvement of fiber addition with respect to HDPE in all composites. But the water absorption was not increased uniformly with the increase of fiber addition in composites. In all cases, composites absorbed water very rapidly up to 80 hrs and then water absorption is in saturated condition. The mechanical properties like tensile strength (TS), flexural strength (FS), impact strength (IS) and hardness were observed to be comparatively more enhanced for 5% composite, while further increasing of fiber addition, all mechanical properties changes irregularly. The irregular nature of change might be caused due to the over loading of fiber in polymer matrix.展开更多
Visible near-infrared (vis-NIR) and portable X-ray fluorescence (pXRF) spectrometers have been increasingly utilized for predicting soil properties worldwide. However, only a few studies have focused on splitting the ...Visible near-infrared (vis-NIR) and portable X-ray fluorescence (pXRF) spectrometers have been increasingly utilized for predicting soil properties worldwide. However, only a few studies have focused on splitting the predictive models by horizons to evaluate prediction performance and systematically compare prediction performance for A, B, and combined A+B horizons. Therefore, we investigated the performance of pXRF and vis-NIR spectra, as individual or combined, for predicting the clay, silt, sand, total carbon (TC), and pH of soils developed in loess, and compared their prediction performance for A, B, and A+B horizons. Soil samples (176 in A horizon and 172 in B horizon) were taken from Mollisols and Alfisols in 136 pedons in Wisconsin, USA and analyzed for clay, silt, sand, pH, and TC. The pXRF and vis-NIR spectrometers were used to measure the pXRF and vis-NIR soil spectra. Data were separated into calibration (n = 244, 70%) and validation (n = 104, 30%) datasets. The Savitzky-Golay filter was applied to preprocess the pXRF and vis-NIR spectra, and the first 10 principal components (PCs) were selected through principal component analysis (PCA). Five types of predictor, i.e., PCs from vis-NIR spectra, pXRF of beams at 0–40 and 0–10 keV (XRF40 and XRF10, respectively) spectra, combined XRF40 and XRF10 (XRF40+XRF10) spectra, and combined XRF40, XRF10, and vis-NIR (XRF40+XRF10+vis-NIR) spectra, were compared for predicting soil properties using a machine learning algorithm (Cubist model). A multiple linear regression (MLR) model was applied to predict clay, silt, sand, pH, and TC using pXRF elements. The results suggested that pXRF spectra had better prediction performance for clay, silt, and sand, whereas vis-NIR spectra produced better TC and pH predictions. The best prediction performance for sand (R2= 0.97), silt (R2= 0.95), and clay (R2= 0.84) was achieved using vis-NIR+XRF40+XRF10 spectra in B horizon, whereas the best prediction performance for TC (R2= 0.93) and pH (R2= 0.79) was achieved using vis-NI展开更多
文摘A significant amount of aluminum dross is available as a waste in foundry industries in Bangladesh. In this study, alumina was ex- tracted from aluminum dross collected from two foundry industries situated in Dhamrai and Manikgang, near the capital city, Dhaka. Alu- minum dross samples were found to approximately contain 75wt% A1203 and 12wt% SIO2. An acid dissolution process was used to recover the alumina value from the dross. The effects of various parameters, e.g., temperature, acid concentration, and leaching time, on the extrac- tion of alumina were studied to optimize the dissolution process. First, AI（OH）3 was produced in the form of a gel. Calcination of the AI（OH）3 gel at 1000℃, 1200℃, and 1400℃ for 2 h produced O-AlcOa, （t~＋O）-A1203, and u-alumina powder, respectively. Thermal charac- terization of the AI（OH）3 gel was performed by thermogravimetric/differential thermal analysis （TG/DTA） and differential scanning calo- rimetry （DSC）. The phases and crystallite size of the alumina were determined by X-ray diffraction analysis. The dimensions of the alumina were found to be on the nano level. The chemical compositions of the aluminum dross and alumina were determined by X-ray fluorescence （XRF） spectroscopy. The microstructure and morphology of the alumina were studied with scanning electron microscopy. The purity of the alumina extracted in this study was found to be 99.0%. Thus, it is expected that the obtained alumina powders can be potentially utilized as biomaterials.
文摘Calcium-based biocomposite materials have a pivotal role in the biomedical field with their diverse properties and applications in combating challenging medical problems. The study states the development and characterization of Calcium-based biocomposites: Hydroxyapatite (HAP), and PVA-Gelatin-HAP films. For the preparation of Calcium-based biocomposites, an unconventional source, the waste material calcite stone, was used as calcium raw material, and by the process of calcination, calcium oxide was synthesized. From calcium oxide, HAP was prepared by chemical precipitation method, which was later added in different proportions to PVA-Gelatin solution and finally dried to form biocomposite films. Then the different properties of PVA/Gelatin/HAP composite, for instance, chemical, mechanical, thermal, and swelling properties due to the incorporation of various proportions of HAP in PVA-Gelatin solution, were investigated. The characterization of the HAP was conducted by X-ray Diffraction Analysis, and the characterization of HAP-PVA-Gelatin composites was done by Fourier Transform Infrared Spectroscopy, Thermomechanical Analysis, Tensile test, Thermogravimetric Differential Thermal Analysis, and Swelling Test. The produced biocomposite films might have applications in orthopedic implants, drug delivery, bone tissue engineering, and wound healing.
文摘With the modern advancement of treatment approaches in medical science, the application of biomaterials in tissue engineering provides a remarkable opportunity to overcome graft rejection as well as proper wound healing. In this study, novel hybrid films have been synthesized by incorporation of polyvinyl alcohol (PVA), gelatin, and gelatin with glycerin along with different concentrations of pre-prepared hydroxyapatite (HAP) by solution casting method at room temperature in a biosafety cabinet. Glutaraldehyde has been added as a crosslinker in this whole procedure. Fourier-transform infrared spectroscopy (FTIR), X-Ray Diffraction (XRD) have been conducted to observe and compare the structural and chemical stability of the synthesized hybrid film properties. The FTIR results and X-Ray Diffraction analyses confirmed the chemical interactions between HAP, PVA, gelatin, and glycerin have occurred. The crystallinity of HAP also remains in all the prepared hybrid film samples that are observed in XRD. It is expected that these newly synthesized hybrid films could be a better opportunity for various sectors of tissue engineering such as skin, bone, tendon, and cartilage. These synthesized hybrid films can be suitable for wound healing covering. These studies could be a new scope for long-term drug delivery directly on wound sites in diabetic gangrene foot or burn patients as well as cartilage or joint replacement therapy.
文摘In the recent research field of bone tissue engineering, polymeric materials play an implacable role in mimes the natural behavior of hard and soft tissues. In some medical conditions such as diabetics, osteoarthritis, burns, or joint replacement conditions, this polymeric materials implication enhances the internal mechanical activities which result in the early recovery of disease by facilitating the wound healing process. In this study, hybrid films have been synthesized based on polyvinyl alcohol (PVA), gelatin, and gelatin with glycerin incorporated with different concentrations of pre-prepared hydroxyapatite (HAP) by solution casting method at room temperature in biosafety cabinet. Glutaraldehyde has been added as a crosslinker in this whole procedure. The mechanical property, swelling, and porosity percentage have been conducted to characterize the structural stability of the synthesized hybrid films. Porosity and swelling of samples are also represented by proper biocompatibility (>90% porosity and swelling in DDW and PBF vary between 287%~72%). Tensile strength (TS), E modulus (Young’s modulus), Elongation at maximum, and Elongation at break are observed to perceive the mechanical properties of hybrid film samples, which are compatible with mechanical properties of different tissue such as trabecular bone, articular cartilage, tendon, nerve and skin tissue. Though, biocompatibility tests both in vivo and in vitro are essential for clinical application in the future. However, the experiment carried out till now explains the true possibility of newly synthesized hybrid films for long-term drug delivery directly on wound sites for wound healing and burn dressing patients in head-neck surgery reconstruction, diabetic gangrene foot, as well as cartilage or joint replacement therapy.
文摘Although there are many lead-free soldering alloys on the market, none of them have ideal qualities. The researchers are combining binary alloys with a variety of additional materials to create the soldering alloys’ features. The eutectic Sn-9Zn alloy is among them. This paper investigated the mechanical and electrical properties of Sn-9Zn-x (Ag, Cu, Sb);{x = 0.2, 0.4, and 0.6} lead-free solder alloys. The mechanical properties such as elastic modulus, ultimate tensile strength (UTS), yield strength (YS), and ductility were examined at the strain rates in a range from 4.17 10−3 s−1 to 208.5 10−3 s−1 at room temperature. It is found that increasing the content of the alloying elements and strain rate increases the elastic modulus, ultimate tensile strength, and yield strength while the ductility decreases. The electrical conductivity of the alloys is found to be a little smaller than that of the Sn-9Zn eutectic alloy.
文摘The development of advanced biomaterials is crucial for addressing the increasing demand for improved medical implants and tissue engineering scaffolds. Hydroxyapatite (HAp), a naturally occurring mineral form of calcium apatite, is widely recognized for its excellent biocompatibility and osteoconductivity, making it an ideal candidate for bone-related applications. However, its brittleness and lack of flexibility limit its broader application in dynamic biological environments. To overcome these limitations, this study explores the synthesis of Hydroxyapatite/Alginate (HAp/Alg) nanocomposites, leveraging the biocompatibility and flexibility of alginate—a natural polysaccharide derived from brown seaweed. The HAp/Alg nanocomposites were synthesized using in situ hybridization techniques with varying alginate concentrations (10 to 40 wt%) to optimize their structural and functional properties. The motivation behind this work lies in the potential of these composites to combine the desirable properties of both HAp and alginate, resulting in a material that not only mimics the mineral composition of bone but also offers enhanced flexibility and structural integrity. A comprehensive analysis was conducted using X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Thermogravimetric Analysis/Differential Thermal Analysis (TGA/DTA), Scanning Electron Microscopy (SEM), and cytotoxicity testing to evaluate the structural, chemical, and biological properties of the composites. XRD analysis indicated a complex interaction between alginate concentration and crystal growth, with crystallite size increasing up to 10 wt% alginate before decreasing. FT-IR spectra confirmed significant biological reactivity at the composite’s surface and within the polymer matrix, suggesting strong potential for biological interactions. SEM images revealed a more uniform microstructure in HAp/Alg composites compared to pure HAp, which is likely to improve their performance in biomedical applications. TGA/DTA results demon
文摘Composites based on jute fabrics and polypropylene was fabricated by heat-press molding technique. The mechanical properties of the composites such as tensile strength, tensile modulus, bending strength, bending modulus and impact strength were measured in dependence of fiber contents. In order to improve fiber-matrix interaction, jute fabrics were treated with aqueous solutions of K2Cr2O7 (0.005-0.05% w/v). Composite prepared with 0.02% K2Cr2O7 treated jute fabrics showed the highest values of the mechanical properties. Thermogravimetric (TG/DTG) data of PP, jute fabrics and composites showed that thermal degradation temperatures of composites shifted to higher temperature regions compared to PP or jute fabrics. Treatment of jute fabrics improved the thermal stability of the composite considerably. Scanning electron microscopic images of tensile fractured sides of untreated and treated composites illustrated that better fiber-matrix interfacial interaction occurred in treated composite. The relative tendency of water absorption of both untreated and treated composites was also explored.
文摘Aluminum based metal matrix composites were fabricated using stir casting where silicon carbide and alumina were the reinforcements. Different types of properties (physical-density, mechanical-tensile, hardness, chemical-corrosion etc.) were measured and compared with base metals/alloys. The properties were significantly varied. The highest density was obtained for pure aluminium with 5% Al<sub>2</sub>O<sub>3</sub> whereas the lowest was obtained for AA-4032 alloy. The highest hardness was obtained for AA-4032 with 5% Al<sub>2</sub>O<sub>3</sub> whereas the lowest was obtained for pure Al with 5% Al<sub>2</sub>O<sub>3</sub>. The highest strength was obtained for AA-6061 with 5% coarse SiC whereas the lowest was obtained for pure Al. The highest impact strength was obtained for AA-4032 with 5% Al<sub>2</sub>O<sub>3</sub> whereas the lowest was obtained for AA-6061. The corrosion resistance of all composites was lower than that of the base materials.
文摘Traditional wastewater mostly contains pharmaceutical ingredients. Therefore, the wastewater must be completely free from antibiotics before its release into the environment. In the present study, photocatalytic degradation was done to investigate the removal efficiency of Oxytetracycline Dihydrate (OTC) using ZnO, ZnO/3%BaTiO<sub>3</sub> (3 BZ), ZnO/18%BaTiO<sub>3</sub> (18 BZ), ZnO/ 33%BaTiO3 (33 BZ) and ZnO/48%BaTiO<sub>3</sub> (48 BZ) under UV light. After the exposure time of 420 min, about 99.57% and 97.87% of OTC was degraded using ZnO and 3 BZ respectively. Further, increasing the amount of BaTiO<sub>3</sub> in ZnO prolongs the degradation time. Therefore, faster efficiency was found using ZnO nanoparticles. The observed reaction rate constant using ZnO was 0.00933 min<sup>-1</sup> which decreased to 0.00532 min<sup>-1</sup> using 48 BZ, indicating the decrease of reaction rate for increasing the amount of BaTiO<sub>3</sub>. Hence, the use of ZnO photocatalyst is anticipated to be a promising technique for the photocatalytic degradation of contaminated wastewater with oxytetracycline antibiotics using UV light.
文摘The tensile properties of Sn-9Zn-xAg-ySb;{(x, y) = (0.2, 0.6), (0.2, 0.8), (0.6, 0.2), (0.8, 0.2)} lead-free solders were investigated. All the test samples were annealed at 150°C for 1 hour. The tests are carried out at room temperature at the strain rate of 4.17 × 10<sup>-3</sup> s<sup>-1</sup>, 20.85 × 10<sup>-3</sup> s<sup>-1</sup>, and 208.5 × 10<sup>-3</sup> s<sup>-1</sup>. It is seen that the tensile strength increases and the ductility decrease with increasing the strain rate over the investigated range. From the strain rate change test results, the strain sensitivity values are found in the range of 0.0831 to 0.1455 due to the addition of different alloying elements.
文摘Zirconia toughened alumina (ZTA) ceramics are very promising materials for structural and biomedical applications due to their high hardness, fracture toughness, strength, corrosion and abrasion resistance and excellent biocompatibility. The effect of unstabilized ZrO<sub>2</sub> on the density, fracture toughness, microhardness, flexural strength and microstructure of some Zirconia-toughened alumina (ZTA) samples was investigated in this work. The volume percentage of unstabilized ZrO<sub>2</sub> was varied from 0% - 20% whereas sintering time and sintering temperature were kept constant at 2 hours and 1580°C. The samples were fabricated from nanometer-sized (<em>α</em>-Al<sub>2</sub>O<sub>3</sub>: 150 nm, monoclinic ZrO<sub>2</sub>: 30 - 60 nm) powder raw materials by the conventional mechanical mixing process. Using a small amount of sintering aid (0.2 wt% MgO) almost 99.2% of theoretical density, 8.54 MPam<sup>?</sup> fracture toughness, 17.35 GPa Vickers microhardness and 495.67 MPa flexural strength were found. It was observed that the maximum flexural strength and fracture toughness was obtained for 10 vol% monoclinic ZrO<sub>2</sub> but maximum Vickers microhardness was achieved for 5 vol% ZrO<sub>2</sub> although the maximum density was found for 20 vol% ZrO<sub>2</sub>. It is assumed that this was happened due to addition of denser component, phase transformation of monoclinic ZrO<sub>2</sub> and the changes of grain size of α-Al<sub>2</sub>O<sub>3</sub> and ZrO<sub>2</sub>.
文摘In the textile industry, cotton is the most popular choice among all the natural fibers due to its unique properties such as softness, affinity to skin, biodegradability, absorbency, and moisture being comfortable to wear. Zinc Oxide Nanoparticles (ZnO NPs) were produced and coated on cotton fabrics. The concentration of Zinc acetate was varied. 2-methoxy-ethanol has been used as a solvent. Using the dip coating technique, ZnO NPs have been coated on the cotton fabric in different mole concentrations. Scanning Electron Microscopy (SEM), Ultraviolet Visible (UV-VIS) spectroscopy, the antifungal and antibacterial activity of the ZnO NPs was performed on the coated fabrics. The SEM images depicted that the nanoparticles are well dispersed on the fabric at 3M concentration of ZnO solution. It was found that the UV absorbance increases with the increase of concentration up to 2M concentration and after that it decreases. It was also found that maximum antibacterial and antifungal activity is at 2M concentration.
文摘The sawdust reinforced Acrylonitrile Butadiene Styrene (ABS) composites were prepared by using hot press molding machine for five different wt% (0%, 5%, 10%, 15% and 20%) at 180<span style="white-space:nowrap;">°</span>C temperature and 50 KN load. Sawdust was collected from local saw mill of Savar, Dhaka, Bangladesh and ABS polymer was collected from local market of Dhaka, Bangladesh. In this study, different properties of composites like physical (bulk density and water absorption), mechanical (tensile properties and hardness) and structural (Fourier Transform Infrared Spectroscopy) properties were studied. The bulk density of composites was not altered consistently and it gave greater value for 5% and 20% composites. The water absorption enhanced for all composites with the accumulation of fiber content and soaking time. The reduction of tensile strength and Leeb’s rebound hardness of the composites were observed with the increase of the fiber content in all compositions. Maximum (%) of elongation was found for 5% composite, and then it gradually decreased;however, elastic modulus increased with the increased of fiber content in composites. Fourier Transform Infrared (FTIR) spectroscopy study was done for structural characterization. It was found that there was a new bond (C≡C) stretching formed for 20% composite;moreover, C-H rocking for 0% composite was broken for all other composites after the addition of sawdust in ABS polymer matrix.
文摘One-band effective mass model is used to simulation of electron gas properties in quantum well. We calculate of dispersion curves for first three subbands. Calculation results of Fermi energy, effective mass at Fermi level as function of electron concentration are presented. The obtained results are good agreement with the experimental dates.
文摘Influence of recombination centers’ changes on the form of phase portraits has been studied. It has been shown that the shape of the phase portraits depends on the concentration of semiconductor materials’ recombination centers.
文摘Fiber Reinforced Thermoplastic (FRTP) composites are emerging as potential materials in many engineering fields. In this research, the compression-molding process was used as the fabrication technique for producing talc-filled reinforced polyester composite. The weight percentage of these composites was varied, like 30 wt%, 40 wt%, 45 wt%, and 50 wt% talc, respectively. Besides, different percentages of styrene monomer, such as 0 wt%, 20 wt%, and 30 wt%, were also used in this study. Different types of physical, chemical, mechanical, and thermal properties were investigated. The water absorption percentage is increased for composites having a higher percentage of talc filler, while the elasticity of the composites shows a decreasing nature with the increase of talc content. Compressive strength is increased with higher talc content. After a certain limit, with the increase of talc content, it decreases and remains more or less constant. The flexural properties (flexural strength, tangent modulus, and flexural strain) of polyester-talc composites are higher initially, and as the percentage of talc increases, the flexural properties decrease or remain constant. The rate of water absorption is very low with the increase in soaking time. The thermal analysis of polyester-talc composites shows that the thermal stability of the composites is better than that of polyester.
文摘Tin oxide (SnO<sub>2</sub>) thin films were deposited on glass substrate by Chemical Bath Deposition (CBD), Drop-Cast and Dip-Coating method. The thin films were post-annealed at 500°C for 2 hours. The structural, optical, and electrical properties of the SnO<sub>2</sub> thin films were investigated by using XRD, FTIR, SEM, EDX, UV-Vis spectroscopy, and Electrometer experiment. The XRD patterns of SnO<sub>2</sub> thin films deposited on glass substrate by CBD method, Drop-Cast method and Dip-Coating method showed cubic, tetragonal and amorphous structures respectively. The FTIR spectrum exhibited the strong presence of SnO<sub>2</sub> with the characteristic vibrational mode of Sn-O-Sn. The SEM analysis was observed that the surface morphology of the thin films toughly depends on the deposition methods of the SnO<sub>2</sub> thin films. EDX measurement confirmed that the thin films are the composition of Tin (Sn) and Oxygen (O<sub>2</sub>). The optical band gap of SnO<sub>2 </sub>thin films deposited by CBD method, Drop-Cast method and Dip-Coating method is found to be 3.12 eV, 3.14 eV and 3.16 eV respectively. Thin films deposited by Dip-Coating method showed the highest band gap. The electrical results confirmed that the SnO<sub>2</sub> thin films are good conductors and pursued Ohm’s Law. These properties of the SnO<sub>2</sub> thin films brand are appropriate for application in solar cell assembly, gas sensor devices and transparent electrodes of panel displays.
文摘In this research work, (Bi<sub>2</sub>O<sub>3</sub>Fe<sub>2</sub>O<sub>3</sub>)<sub>0.4</sub>(Nb<sub>2</sub>O<sub>5</sub>)<sub>0.6</sub> was made by the solid state reaction method. Samples were sintered at four different temperatures (850°C, 925°C, 1000°C and 1150°C) to study the effect of sintering temperature on the various properties of the samples. X-ray diffraction analysis confirmed that single phase Bi<sub>1.721</sub>δ<sub>0.089</sub>Fe<sub>1.056</sub>Nb<sub>1.134</sub>O<sub>7</sub> was found when sintering temperature increased. At the same time, larger grain size was found when sintering temperature increased. From variation of dielectric loss with respect to frequency, a small peak was found when sample was sintered at higher temperature (1150°C). Dielectric constant of the sample decreases with the increase of frequency for all the samples. With the variation of temperature, DC resistivity of the samples showed that resistivity decreases with the increase of measuring temperature which indicates semiconducting nature.
文摘Fiber-reinforced polymer (FRP) composites have gradually gained wide acceptance as engineering material applications due to their unique advantages including their high strength-to-weight ratio and excellent corrosion resistance. This study was carried out with composites prepared by hot press molding method using coconut spathe fiber as reinforcing material and HDPE (from HDPE can as obsolete polymer) as polymer matrix. Composites were made at 150°C under 60 kN load by taking diverse weight percentage (wt.%) of fiber from 0 to 20 of its total weight. In this research investigation, different properties of the composites such as bulk density, water absorption, tensile and flexural properties, impact strength and hardness test properties were carried out. The fiber content enhancement increases the bulk density in all composites. The rate of water absorption improves with the improvement of fiber addition with respect to HDPE in all composites. But the water absorption was not increased uniformly with the increase of fiber addition in composites. In all cases, composites absorbed water very rapidly up to 80 hrs and then water absorption is in saturated condition. The mechanical properties like tensile strength (TS), flexural strength (FS), impact strength (IS) and hardness were observed to be comparatively more enhanced for 5% composite, while further increasing of fiber addition, all mechanical properties changes irregularly. The irregular nature of change might be caused due to the over loading of fiber in polymer matrix.
基金supported by the Scientific Research Projects(BAP)(No.2019-2757)of Eskisehir Osmangazi University for postdoc research at the Department of Soil Science,University of Wise on sin-Madison.
文摘Visible near-infrared (vis-NIR) and portable X-ray fluorescence (pXRF) spectrometers have been increasingly utilized for predicting soil properties worldwide. However, only a few studies have focused on splitting the predictive models by horizons to evaluate prediction performance and systematically compare prediction performance for A, B, and combined A+B horizons. Therefore, we investigated the performance of pXRF and vis-NIR spectra, as individual or combined, for predicting the clay, silt, sand, total carbon (TC), and pH of soils developed in loess, and compared their prediction performance for A, B, and A+B horizons. Soil samples (176 in A horizon and 172 in B horizon) were taken from Mollisols and Alfisols in 136 pedons in Wisconsin, USA and analyzed for clay, silt, sand, pH, and TC. The pXRF and vis-NIR spectrometers were used to measure the pXRF and vis-NIR soil spectra. Data were separated into calibration (n = 244, 70%) and validation (n = 104, 30%) datasets. The Savitzky-Golay filter was applied to preprocess the pXRF and vis-NIR spectra, and the first 10 principal components (PCs) were selected through principal component analysis (PCA). Five types of predictor, i.e., PCs from vis-NIR spectra, pXRF of beams at 0–40 and 0–10 keV (XRF40 and XRF10, respectively) spectra, combined XRF40 and XRF10 (XRF40+XRF10) spectra, and combined XRF40, XRF10, and vis-NIR (XRF40+XRF10+vis-NIR) spectra, were compared for predicting soil properties using a machine learning algorithm (Cubist model). A multiple linear regression (MLR) model was applied to predict clay, silt, sand, pH, and TC using pXRF elements. The results suggested that pXRF spectra had better prediction performance for clay, silt, and sand, whereas vis-NIR spectra produced better TC and pH predictions. The best prediction performance for sand (R2= 0.97), silt (R2= 0.95), and clay (R2= 0.84) was achieved using vis-NIR+XRF40+XRF10 spectra in B horizon, whereas the best prediction performance for TC (R2= 0.93) and pH (R2= 0.79) was achieved using vis-NI
