Scanning Electron Microsopy Research Articles

Protection of gemcitabine-loaded polylactic-co-glycolic acid microspheres combined with CAR-T treatment against pancreatic ductal adenocarcinoma

Pancreas ductal adenocarcinoma has a highly aggressive phenotype and is one of the most lethal malignancies in the world. Although the use of FOLFIRINOX and abraxane plus gemcitabine chemotherapy regimens have improved patient care, their recurrence rates and long-term survival are still not promising. In this study, PLGA/gemcitabine microspheres were prepared by emulsification–solvent volatilization using gemcitabine as the drug model, and scanning electron microsopy showed that the microspheres had a smooth surface, small size, and large specific surface area. The PLGA microspheres have a high loading capacity and are capable of long-term release. The combination of PLGA/gemcitabine microspheres with chimeric antigen receptor T-cell treatment can regulate MUC1 expression in epithelial cells and reduce the aggressiveness of tumors; thus, it is expected to be applied in the treatment of pancreatic ductal adenocarcinoma.

Development of Methods for Specific Capture of Biological Targets on Aluminum Substrates: Application to Bacillus subtilis Spore Detection as a Model for Anthrax.

Many (if not most) biosensors rely on functional silane coatings as a first step toward covalent immobilization of specific capture molecules. While methods for silanization of silica (SiO2) surfaces are very well developed, less has been done to develop and characterize silanization methods for alternative substrates, such as alumina (Al2O3). In particular, the behavior of Al2O3 coatings grown on aluminum under ambient conditions has not been studied. To address this issue, we have tested solution-phase deposition of two silanes on Al2O3 (3-aminopropyl triethoxysilane and 3-triethoxysilyl)propylsuccinic anhydride) and their applicability to analyte-specific biosensing. Contact angle measurements and imaging via Scanning Electron Microsopy (SEM) were employed to characterize surfaces. We find that 3-aminopropyl triethoxysilane produces well-behaved films and demonstrate that this surface can undergo further reaction with glutaraldehyde followed by an anti-Bacillus subtilis antibody to yield functionalized Al2O3 surfaces capable of specific capture of B. subtilis spores (a model of B. anthracis, the causative organism of Anthrax). In contrast, 3-triethoxysilyl)propylsuccinic anhydride did not behave well with Al/Al2O3 under the reaction conditions tested. In addition to providing specific protocols for Al/Al2O3 functionalization, this work highlights the importance of surface chemistry assessment in the development of new sensors.

Effect of High Doses Gamma Irradiation on Texturing of Bi2Sr2CaCu2O8 (Bi-2212) Superconductor

The effect of high doses gamma irradiation on the texture and microstructure of Bi2Sr2CaCu2O8 (Bi-2212) superconductor is studied in order to observe the sustainability of the material in radiation environment such as gamma radiation. The prepared samples have been irradiated with 100 kGray (kGy) of gamma irradiation and investigated by powder X-ray diffraction (XRD) and scanning electron microsopy (SEM). The Texture Coefficient (TC) for both the non-irradiated and irradiated samples has been calculated. The XRD patterns of the samples showed the Bi-2212 phase as the dominant phase. However, reduction in the intensity of Bi-2212 phase is observed in the gamma irradiated sample. Furthermore the calculated TC percentage of the irradiated sample have lower values when compared to the non-irradiated sample. The SEM micrograph of the irradiated sample showed random grains orientation with poorly connected inter and intra-grain microstructure that are in agreement with the calculated TC percentage.

Effect of Carbon Additives on the Electrochemical Performance of Li4Ti5O12/C Anodes

The Li4Ti5O12/C composites were prepared by a hydrothermal method with in situ carbon addition. The influence of the morphology and content of various carbon materials (conductive carbon black, mesoporous carbon G_157M, and carbon replicas) on the electrochemical performance of the Li4Ti5O12/C composites was investigated. The obtained composites were characterized using X-ray diffraction, scanning electron microsopy, high-resolution transmission electron microscopy, thermogravimetric analysis, Raman spectroscopy, and N2 sorption-desorption isotherms. Morphology of the Li4Ti5O12/C composites depends on the carbon matrix used, while both morphology and the amount of carbon material have a great impact on the rate capability and cycling stability of the obtained composites. At low current densities, the Li4Ti5O12/C composite with 5 wt.% G_157M exhibits the highest discharge capacity, while at high charge-discharge rates, the Li4Ti5O12/carbon black composites show the best electrochemical performance. Thus, at ~0.1C, 5C, and 18C rates, the discharge capacities of the obtained Li4Ti5O12/C composites are 175, 120, and 70 mAh/g for G_157M, 165, 126, and 78 mAh/g for carbon replicas, and 173, 128, and 93 mAh/g for carbon black. After 100 cycles, their capacity retention is no less than 95%, suggesting their promising application perspective.

Applications of chitosan (CHI)-reduced graphene oxide (rGO)-polyaniline (PAni) conducting composite electrode for energy generation in glucose biofuel cell

A glassy carbon electrode (GC) immobilized with chitosan (CHI)@reduced graphene (rGO)-polyaniline (PAni)/ferritin (Frt)/glucose oxidase (GOx) bioelectrode was prepared. The prepared electrode was characterized by using cyclic voltammetry (CV), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) techniques. The morphological characterization was made by scanning electron microsopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. This bioelectrode provided a stable current response of 3.5 ± 0.02 mAcm−2 in 20 mM glucose. The coverage of enzyme on 0.07 cm2 area of electrode modified with CHI@rGO-PAni/Frt was calculated to be 3.80 × 10−8 mol cm−2.

Zero Cu valence and superconductivity in high-quality CuxBi2Se3 crystal

In this work, the role of Cu dopants in the development of superconductivity in $\mathrm{B}{\mathrm{i}}_{2}\mathrm{S}{\mathrm{e}}_{3}$ is investigated. A series of $\mathrm{C}{\mathrm{u}}_{x}\mathrm{B}{\mathrm{i}}_{2}\mathrm{S}{\mathrm{e}}_{3}$ ($x=0--0.3$) crystals is grown using the Bridgman method and electrochemical techniques. Based on the observable lattice increases along the $c$ axis, the existence of Cu atoms intercalated in the van der Waals (vdW) gaps in $\mathrm{B}{\mathrm{i}}_{2}\mathrm{S}{\mathrm{e}}_{3}$ is verified by x-ray diffraction, scanning electron microsopy--energy dispersive spectroscopy, and transmission electron microscopy analysis. Furthermore, the chemical state of the Cu is found to be zero valence by characterization of the x-ray photoelectron and Auger electron spectra. The absence of $\mathrm{C}{\mathrm{u}}^{1+}$ and $\mathrm{C}{\mathrm{u}}^{2+}$ in the electron energy-loss spectroscopy near-edge fine structure is confirmed as well. Meanwhile, our Raman data also show the same result: the intercalation of Cu in the vdW gap which weakens the binding of the quintuple layers in the $\mathrm{C}{\mathrm{u}}_{0.1}\mathrm{B}{\mathrm{i}}_{2}\mathrm{S}{\mathrm{e}}_{3}$ crystal. The electric resistance and magnetic susceptibility show a superconducting transition near 3--3.4 K in the series of Cu-doped $\mathrm{B}{\mathrm{i}}_{2}\mathrm{S}{\mathrm{e}}_{3}$. A sharp superconducting transition with the highest value of ${T}_{C}=3.4\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ and the largest magnetic shielding fraction of 84% is observed in the optimized 10% Cu-doped $\mathrm{B}{\mathrm{i}}_{2}\mathrm{S}{\mathrm{e}}_{3}$. These results imply that the formation of superconducting quasiparticles is not related to the charge transfer of Cu, but is supported by the internal stress of Cu intercalated in the van der Waals gap. The superconducting transition observed in the specific heat implies that the superconductivity in $\mathrm{C}{\mathrm{u}}_{x}\mathrm{B}{\mathrm{i}}_{2}\mathrm{S}{\mathrm{e}}_{3}$ is unconventional.

Optimization of Electrochemical Performance of LiFePO4/C by Indium Doping and High Temperature Annealing

We have prepared nano-structured In-doped (1 mol %) LiFePO4/C samples by sol–gel method followed by a selective high temperature (600 and 700 °C) annealing in a reducing environment of flowing Ar/H2 atmosphere. The crystal structure, particle size, morphology, and magnetic properties of nano-composites were characterized by X-ray diffraction (XRD), scanning electron microsopy (SEM), transmission electron microscopy (TEM), and 57Fe Mössbauer spectroscopy. The Rietveld refinement of XRD patterns of the nano-composites were indexed to the olivine crystal structure of LiFePO4 with space group Pnma, showing minor impurities of Fe2P and Li3PO4 due to decomposition of LiFePO4. We found that the doping of In in LiFePO4/C nanocomposites affects the amount of decomposed products, when compared to the un-doped ones treated under similar conditions. An optimum amount of Fe2P present in the In-doped samples enhances the electronic conductivity to achieve a much improved electrochemical performance. The galvanostatic charge/discharge curves show a significant improvement in the electrochemical performance of 700 °C annealed In-doped-LiFePO4/C sample with a discharge capacity of 142 mAh·g−1 at 1 C rate, better rate capability (~128 mAh·g−1 at 10 C rate, ~75% of the theoretical capacity) and excellent cyclic stability (96% retention after 250 cycles) compared to other samples. This enhancement in electrochemical performance is consistent with the results of our electrochemical impedance spectroscopy measurements showing decreased charge-transfer resistance and high exchange current density.

Formation of hydroxyapatite on titanium implants in vivo precedes bone-formation during healing

The bone material interface has been an area of intense study over many decades, where studies of the healing process ranging from simple mineral deposition in vitro to actual healing in vivo have given important clues to the importance of calcium minerals in the bone/implant interface. Here, the authors use a combination of in vitro cell culture methods and in vivo implantation to study how the role of the spontaneously formed hydroxyapatite layer on Ti-implants for the in vivo-healing into the bone tissue of rat tibia. Initial experiments were made in reduced systems by incubation of TiO2 in cell culture medium and analysis by time of flight secondary ion mass spectrometry (ToF-SIMS) and energy-dispersive x-ray spectroscopy followed by subsequent exposure of human embryological stem cells analyzed by von Kossa staining and environmental scanning electron microsopy. In vivo studies of the bone-material interface was analyzed by ToF-SIMS depth profiling using both C60+ ions as well as a gas cluster ion source beam, Ar1500+ as sputter source. The low ion yield of the Ar1500+ for inorganics allowed the inorganic/organic interface of the implant to be studied avoiding the erosion of the inorganic materials caused by the conventional C60+ beam.

RF sputtered SnO2: NiO thin films as sub-ppm H2S sensor operable at room temperature

A room temperature sub-ppm H2S sensor based on RF sputtered SnO2: NiO thin film has been demonstrated. For this, SnO2 thin films have been modified with ultrathin layers (30nm) of NiO. These films were characterized using Scanning electron Microsopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Gas sensing properties of these films were systematically investigated and compared with those of pure SnO2 and NiO films. Sensing studies revealed that these films are highly sensitive to H2S at room temperature. The sensor response exhibited by NiO modified SnO2 film, is 9 and 415 times greater than that exhibited by pure SnO2 and NiO films, respectively. The sensor response in case of SnO2:NiO is due to contribution from two different mechanisms- (i) oxidation reaction between adsorbed oxygen and H2S and (ii) destruction of p-n junctions due to conversion of Nickel Oxide to metallic Nickel Sulphide (product of chemical reaction between NiO and H2S). Presence of XPS sulphide peaks at binding energies of ∼163eV corresponding to S-2p3/2 and S-2p1/2, on H2S exposure confirms the formation of Nickel Sulphide. Present experiments proved the ability of these films to detect low concentrations of H2S i.e. parts per billion reproducibly. These films were also found to be stable for extended period of time, hinting at commercial viability of the sensor.

Development of Ionothermal Synthesis of Titania Nanomaterial for Waste-Water Treatment

In this study, ionothermal synthesis process has been used for the preparation of two different types of Titania nanomaterials and that were utilized in the degradation of waste-water like (sulfan blue). The ionic liquid were used as 1-butyl-3-methylimidazolium dimethyl phosphate ([Bmim] DMP) as (TP) and 1-butyl-3-methypyridium dicyanamide ([Bmpm]DCN) as (TCN) respectively for the synthesis of anatase type Titania nanomaterials and confirmed with X-Ray diffraction pattern (XRD). The particle sizes and surface morphology were characterized by field emission scanning electron microsopy (FESEM), transmission electron microscopy (TEM), and Brunauer-Emmett-Teller (BET). The sizes of the particle were found to be approximately 35±5 nm from the microscopic picture analysis. The nitrogen adsorption analysis measured a surface area of 455 and 220 m2 g-1 and pore volume of 0.25 and 0.15 cm3 g-1 for ([Bmim]DMP) and ([Bmpm]DCN) related synthesis TiO2 nanomaterials respectively.The degradation rate of sulfan blue is higher in the presence of TP as compared to TCN owing to the larger surface area.

Physico-mechanical characterization and biodegradability behavior of polypropylene/poly(L-lactide) polymer blends

Abstract Partially biodegradable polymer films from the blends of polypropylene (PP) and poly(L-lactide) (PLLA) were prepared in an internal mixer by melt blending technique, with and without compatibilizer, maleic anhydride grafted polypropylene (MAPP), followed by compression molding. With regard to tensile properties, 80/20 (PP/PLLA) and 80/20/6 (PP/PLLA/MAPP) were found as the optimum blends with best combination of the ingredients. Therefore, the blend samples, namely, PP80 (80% PP+20% PLLA) and PP80C6 (80% PP+20% PLLA+6 phr MAPP) were selected as ‘optimized’ blends and further characterized for their physical, chemical, morphological, and thermal properties. X-ray diffraction studies showed that neat PP and PP80C6 had the same crystallite size indicating compatibility between PP and PLLA due to MAPP. Fourier transform infrared spectroscopy and scanning electron microsopy investigations revealed that the two polymers were completely immiscible in absence of the compatibilizer. Bacterial biodegradation of the samples was performed by exposure to Pseudomonas stutzeri for 60 days and measured in terms of weight loss, optical density, and thermal stability of the samples before and after degradation. The results showed that 80/20 (PP/PLLA) blends undergo considerable degradation. Reduction in thermal stability of the film samples was also observed through thermogravimetric analysis, which was useful in accelerating their biodegradation.

Revision of the family Carabodidae (Acari, Oribatida) VII. Redefinition of the genus Malgasodes; redescription of M. curvisetus Mahunka, 2000; and complementary description of M. hungarorum Mahunka, 2010. Phylogenetic relationships between Malgasodes, Bovicarabodes, Afticarabodes, Congocepheus and Cavaecarabodes are discussed.

The genus Malgasodes is redefined; the type species M. curvisetus Mahunka, 2000, is redescribed by means of studies using optic and Scanning Electron Microsopy (SEM), and a complementary description of M. hungarorum Mahunka, 2000 is included. Comparison of genera Malgasodes Mahunka, 2000, Bovicarabodes Fernandez, Theron, Rollard, 2013a, Cavaecarabodes Fernandez, Theron, Rollard, Rodriguez Castillo, 2014, Afticarabodes Fernandez, Theron, Rollard, 2013b, and Congocepheus Balogh, 1958 is made. Problems concerning chaetotaxy, regressive evolution and neotrichy are explained and phylogenetic relationships between Malgasodes, Bovicarabodes, Afticarabodes, Congocepheus and Cavaecarabodes are discussed.

The effects of naturally occurring acids on the surface properties of chrysotile asbestos

Chrysotile asbestos is considered an environmental health hazard. It is postulated that the surface of chrysotile, with its inherent positive charge and chemical content of trace transition metals within the mineral is a causative factor of the concern. Weathering may reduce the negative health effects of chrysotile asbestos, by alteration of the outer brucite layer of the chrysotile. To assess the changes in the surface properties of chrysotile asbestos by simulated weathering, chrysotile was treated with oxalic, hydrochloric, and carbonic acids. Naturally occurring chrysotile, from a mine site and serpentinitic stream sediments from the Sumas River were analyzed and compared. Oxalic acid, a chelating acid, was the most effective at extracting the majority of the trace elements present in the chrysotile, reducing their positive surface charge and producing visible changes at the surface of the fibers as shown by Field Emission Scanning Electron Microsopy (FESEM). Carbonic acid had little effect on the surface properties. Stream environments had minor detectable effects on the surface properties on the chrysotile stream sediments.

Effects of Iron Dopants on Barium Strotium Titanate (Ba<sub>0.8</sub>Sr<sub>0.2</sub>TiO<sub>3</sub>) Thin Films

BST thin films have been grown by Chemical Solution Deposition (CSD) method on the substrate of Pt/Si. The fabrication of BST doped by Fe have been successfully using spin coater with 4000 rpm during 30 second. Annealing process use the holding time at 3 hours, the heating rate at 5°C/min and temperature at 800°C. The ratio of Ba0.8Sr0.2TiO3 molar and Fe variant dopant (0%, 1%, 3%, and 5%) were characterized by X-Ray Diffraction (XRD) and obtaining results that show the peak shift due to variations dope. The peak shifted to the right for each increment Fe dopant. Results of addition Fe dopant also cause a differences in the magnitude of Full Width at Half Maximum <em>(</em>FWHM) and lattice parameters on BST ferroelectric materials. Other characterize that has been done by Scanning Electron Microsopy (SEM), it is show the thickness of the material. The resulting lattice parameters with the General Structure Analysis System (GSAS) software analysis showed that a thin films of BST and BSTF have a tetragonal structure because it has a value of a=b≠c and α=β=γ=900. Based on SEM characterization, the thickness of thin film is about 330 nm.

The Structure and Ferromagnetic Properties of the Single Phase Bi<sub>0.95</sub>Eu<sub>0.05</sub>Fe<sub>0.95</sub>Co<sub>0.05</sub>O<sub>3</sub> Nanoparticles Prepared by Sol-Gel

Bi0.95Eu0.05Fe0.95Co0.05O3 Nanoparticles sample was prepared by sol-gel process. The microstructure of samples was analysised by X-ray diffraction(XRD), the result indicated that it was the single phase rhombohedral perovskite structure. The morphology of samples was measured by scanning electron microsopy(SEM), the SEM photograph of samples indicated that the nanoparticles of Bi0.95Eu0.05Fe0.95Co0.05O3 sample were small than that of BiFeO3. The valence states of Fe ions in the samples was analysised by the X-ray absorption spectroscopy（XAS）. The XAS of Fe2p showed that it was the mixed valence states (Fe2+ and Fe3+) of Fe ions in samples, and the binding energy of Bi0.95Eu0.05Fe0.95Co0.05O3 was bigger than that of BiFeO3.The magnetic characteristics of the samples were measured by vibrating sample magnetometer (VSM)，the results showed that the weak metamagnetism were obtained from clear hysteresis loop and the magnetic saturation reached 0.408emu/g，compared with BiFeO3 sample, the magnetic properties were significantly enhanced.

Applications of Modern Analysis Techniques in Searching back Ancient Art Ceramic Technologies

This report highlights the promising applications of modern analysis techniques such as Scanning Electron Microsopy, X-ray fluorescence, X-ray diffraction, Raman scattering spectroscopy, and thermal expansion measurement in searching back the ancient art ceramics technologies.

Optimising by the response surface methodology the enzymatic elimination of clogging of a microfiltration membrane by pectin cake

SummaryThe aim of this paper, in which clogging occurs on the filter at a constant vacuum pressure and constant pectin weight, is to find the optimal values of the variables, temperature and time, to know the best conditions to reduce this clogging by enzymatic hydrolysis. Moreover, different properties of the compression of the cake in the filter were determined such as the filtering medium total resistance (RfT), bed porosity (ε) and the cake‐specific resistance (α) at different times and temperatures. The filter area was 0.142 m2, and the value of the mass fraction of solids in the filtered suspension (S) was 0.12. Scanning electron microsopy (SEM) analyses were performed. The results showed that the compressive stress corresponding to the cake improves the flow rate in the filtration flux at the optimal temperature and time for the process, where the enzyme reaches its highest activity. The test results of this study can be applied in different system of filters during cross‐flow filtration.

Epoxy resin nanocomposites reinforced with ionized liquid stabilized carbon nanotubes

Epoxy resin nanocomposites reinforced with three different ionic liquid functionalized carbon nanotubes (f-CNTs) were fabricated by an in situpolymerization method. The influence of the anions on the curing process was studied through differential scanning calorimetry (DSC) and normalized Fourier transform infrared (FTIR) spectroscopy. The composition of the nanocomposites was analyzed by X-ray photoelectron spectroscopy. Two different mechanisms are proposed to explain the curing process of the neat epoxy and its composites. The electric conductivity and mechanical properties of the nanocomposites are also reported. The tensile strength was increased dramatically due to the insertion of f-CNTs. Scanning electron microsopy fracture surface analysis indicates a strong interfacial bonding between the carbon nanotubes and the polymer matrix.

Analysis and Optimization of Operating Parameters of a Membrane‐Electrode Assembly

AbstractHot‐pressing conditions for fabricating a membrane‐electrode assembly (MEA) were optimized. The key parameters were time, temperature, and pressure, varying from 1 to 5 min, 100 to 170 °C, and 21 to 93 kg cm–2, respectively. The MEAs were fabricated with 50 cm2 active electrode area and their performance was investigated using a fuel cell test station. The most suitable hot‐pressing time for MEA was 3 min, the optimized pressure and temperature for MEA fabrication were 21 kg·cm–2 and 130 °C with 1.6 A and 0.56 V. At 100 °C, the current and voltage of the produced MEAs were low due to the trapped liquid formed inside the electrode. However, at more than 150 °C, the obstructed/distorted polytetrafluoroethylene (PTFE) will block the pores inside the gas diffusion layer (GDL) and cause a loss of performance of the fuel cell. Physical properties of the GDL were observed using scanning electron microsopy (SEM). The GDL exhibited a uniform pore distribution after application of hot‐pressing.

Processing of Nano Hydroxyapatite from Eggshell and Seashell

Hydroxyapatite (HAp) was successfully produced from recycled eggshell, seashell and phosphoric acid by using two different type of milling method (attrition milling and ball milling). According to the analysis, the attrition milling resulted nanosize HAp even after milling, while the ball milling process provided HAp only after a 400oC, 2 h long heat treatment. The grain size in both cases were approximately preserved during the heat treatment. The effect of temperature on stoichiometry, morphology and crystallinity of HAp powders were investigated. The structures of the HAp were characterized by X-ray diffraction and Scanning Electron Microsopy.