Modification Of Ag Research Articles

Sustainable carbonaceous material from durian peel to modify the photocatalytic activity of Ag/activated carbon/BiVO4 for RhB degradation under visible light irradiation

High performance and sustainable Ag/activated carbon (AC)/BiVO4 photocatalyst was synthesized via hydrothermal method, followed by photodeposition of Ag. The AC was derived from organic waste of Monthong durian peels which was recycled to achieve carbon neutrality and encourage sustainable friendly environment. The AC modified band energy and promoted reducing power of the obtained photocatalyst with increasing of oxygen vacancies for electron trapping on the photocatalyst surface, thus enhancing photoexcited charge separation and producing more active species as evidenced by PL, EIS, and scavenger experiment. With the modification of Ag, the photoexcited electrons are efficiently trapped that the available h+ are mobilized through the oxygen vacancies occurring by modified high electron density of AC and Ag thus enhanced photocatalytic performance as exhibited by XPS. The band energy alignment of the developed Ag/AC/BiVO4 is proposed with the improved photocatalytic RhB degradation.

Modified Ag-ZnO coated graphene oxide ternary composite for superior photocatalytic degradation of crystal violet dye under visible light irradiation

The enhancement of advanced nanomaterials into photocatalytic applications has preserved a significant curiosity for its potential to address environmental challenges. To address this concern, a green and eco-friendly catalyst was fabricated. In this study, we examined the enhancement of the photocatalytic activity of various synthesized composites with the modification of graphene oxide (GO) and Ag over the surface of semiconductor zinc oxide (ZnO). The simple wet chemical method was used for the synthesis of ZnO, GO(x)@ZnO, Ag2@ZnO and GO(x)Ag2-ZnO composites [x = 1,3,5 wt%]. The synthesized samples were characterized by different techniques such as XRD, SEM-EDS, DRS, Raman, and PL. Ternary GO5@Ag2-ZnO photocatalyst exhibited superior degradation efficiency up to 97 % in degrading crystal violet (CV) dye, a persistent and environmentally concerning pollutant under visible light irradiation. The significant photocatalytic activity was attributed to the surface plasmon resonance (SPR) phenomenon of Ag, whose broad absorption band was observed in DRS, better electron mobility, and a large surface area of GO facilitates the charge transfer. The highly efficient catalyst was effectively employed for five repeating cycles with only an 11 % decrease in removal rate, demonstrating that it can be easily reused. Kinetic study reveals that the prepared composite follows a pseudo-first-order reaction model with the highest rate constant value of 0.02491 min−1 respectively. The possible degradation pathway was determined using the HRMS technique.

Ag-modification argyrodite electrolytes enable high-performance for all-solid-state lithium metal batteries

Solid-state batteries combined with high-voltage layered cathode and lithium metal anode display good safety and high energy density, showing great potential as next-generation energy storage devices. However, the low ionic conductivity and poor stability with lithium metal of most solid electrolytes inhibit the development of solid-state lithium metal batteries. Herein, Ag+ is successfully integrated into Li5.5PS4.5Cl1.5 structure with improved ionic conductivity and better lithium metal stability for the yielded Li5.5-xAgxPS4.5Cl1.5 (x = 0, 0.02, 0.05, 0.10) electrolytes. Ag+ dopant is carefully tailored to achieve the optimal Li5.45Ag0.05PS4.5Cl1.5 electrolyte with a high Li-ion conductivity of up to 9.1 mS cm−1 and a large CCD value of 1.8 mA cm−2. The corresponding battery with LiNi0.6Mn0.2Co0.2O2 cathode and Li-In anode delivers a high initial discharge capacity of 154.9 mAh g−1 at 1.0C and maintains 94.5% of this value after 100 cycles. However, the same cathode shows low discharge capacities and fast degradation of capacities with bare lithium metal anode in solid-state batteries. A facial 3D host lithium metal with Ag and LiNO3 particles on the surface is designed as the anode for this battery, showing much higher capacities and superior cyclability at different C-rates. The corresponding battery delivers discharge capacities of 140.6 mAh g−1 and 105.4 mAh g−1 when cycled at 0.1C and 0.5C. These superior electrochemical performances are attributed to the dual modification of Ag+ both in solid electrolytes and lithium metal anodes.

Enhanced photocatalytic ammonia oxidation activity and nitrogen selectivity over Ag/AgCl/N-TiO2 photocatalyst

The removal of ammonia (NH3) emitted from agricultural and industrial activities is of great significance to protect human health and ecological environment. Photocatalytic NH3 oxidation to N2 under mild conditions is a promising strategy. However, developing visible light photocatalysts for NH3 oxidation is still in its infancy. Here, we fabricate N-TiO2 and Ag/AgCl/N-TiO2 photocatalysts by sol-gel and photodeposition methods, respectively. The introduction of N not only endows TiO2 with visible light response (absorption edge at 460 nm) but also results in the formation of heterophase junction (anatase and rutile). Thus, N-TiO2 shows 2.0 and 1.8 times higher than those over anatase TiO2 and commercial TiO2 for NH3 oxidation under full spectrum irradiation. Meanwhile, surface modification of Ag can simultaneously enhance visible light absorption (generating localized surface plasmon resonance effect) and charge separation efficiency. Therefore, the photocatalytic activity of Ag/AgCl/N-TiO2 is further improved. Furthermore, the presence of N and Ag also enhances the selectivity of N2 product owing to the change of reaction pathway. This work simultaneously regulates photocatalytic conversion efficiency and product selectivity, providing some guidance for developing highly efficient photocatalysts for NH3 elimination.

Surface modification of Ag–CdO with polyaniline for the treatment of 3′,3″,5′,5″-tetrabromophenolsulfonphthalein (BPB) under UV-visible light irradiation

The quality of natural waters could be deteriorated by organic pollutants which can impose a risk to the ecosystem as well as human health. These organic contaminants are often needed to be removed with adequate techniques. In this study, the photocatalysts of CdO nanoparticles (NPs), Ag–CdO nanocomposites (NCs), and Ag–CdO/polyaniline (PANI) NCs were successfully synthesized in order to investigate their degradation performance against 3′,3″,5′,5″-tetrabromophenolsulfonphthalein (bromophenol blue, BPB) dye. The crystal structure, functional groups, morphological change, and degradation efficiency of as-synthesized photocatalysts were characterized using XRD, FTIR, SEM and UV-Visible spectroscopic techniques respectively. The SEM result showed that the surface morphology of the nanomaterials seems the agglomerated micron-scaled grains as compared to CdO NPs and Ag–CdO NCs. The FT-IR spectrum demonstrated the absorption peaks which strongly confirmed that Ag–CdO NCs surface was successfully modified with PANI. The highly sharp and intensive XRD patterns attributed to the cubic structure for CdO NPs and Ag–CdO NCs structures with decreasing crystalline size from 40.58 nm to 36.43 nm and 10.29 nm upon CdO NPs photocatalyst surface treatment with Ag metal and PANI. The decreased particle size brought about to narrow the bandgap from 2.76 eV to 1.61 eV and 1.58 eV respectively. Among the synthesized photocatalysts, Ag–CdO/PANI NCs exhibited the best degradation efficiency of 97.30 % at pH 6, 10 ppm concentration of dye, 0.140 g of catalyst load, and 210 min irradiation time. Moreover, the kinetics of photodegradation of model dye at optimum conditions followed pseudo-second order reaction with the rate constant of 8.56 × 10-2 M-1min-1. The results suggested that, the developed treatment method for this particular dye could be applicable for the treatment of wastewater samples containing acidic dyes.

Synthesis and Characterization of Indium Tin Oxide Nanowires with Surface Modification of Silver Nanoparticles by Electrochemical Method.

In this study, indium tin oxide nanowires (ITO NWs) with high density and crystallinity were synthesized by chemical vapor deposition (CVD) via a vapor–liquid–solid (VLS) route; the NWs were decorated with 1 at% and 3 at% silver nanoparticles on the surface by a unique electrochemical method. The ITO NWs possessed great morphologies with lengths of 5~10 μm and an average diameter of 58.1 nm. Characterization was conducted through transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscope (XPS) to identify the structure and composition of the ITO NWs. The room temperature photoluminescence (PL) studies show that the ITO NWs were of visible light-emitting properties, and there were a large number of oxygen vacancies on the surface. The successful modification of Ag was confirmed by TEM, XRD and XPS. PL analysis reveals that there was an extra Ag signal at around 1.895 eV, indicating the potential application of Ag-ITO NWs as nanoscale optical materials. Electrical measurements show that more Ag nanoparticles on the surface of ITO NWs contributed to higher resistivity, demonstrating the change in the electron transmission channel of the Ag-ITO NWs. ITO NWs and Ag-ITO NWs are expected to enhance the performance of electronic and optoelectronic devices.

Effect of silver incorporation on the photocatalytic degradation of Reactive Red 120 using ZnS nanoparticles under UV and solar light irradiation

In this work, the Ag modified ZnS nanoparticles were synthesized via the hydrothermal method, and used for photocatalytic degradation of organic dyes. Various analytical techniques were utilized to characterize the prepared ZnS and Ag incorporated ZnS nanoparticles. The vibrational and structural properties of the prepared nanoparticles were analyzed by FT-IR and XRD, which confirm the modification of Ag in the ZnS. The broadening of the hydroxyl group after incorporation of Ag in ZnS was observed in the FT-IR spectra. The additional (111), (200), and (220) planes in XRD of Ag–ZnS belong to the silver. The increased absorbance in the entire visible region facilitates the ZnS/Ag photocatalytic performance under direct sunlight. ZnS/Ag nanoparticles showed excellent photocatalytic activity toward degradation of RR 120, DB 15, and AB 1. The ZnS/Ag catalyst efficiently degrades the RR 120 under sunlight with higher pseudo-first order kinetic k = 0.0179 min−1 than the other dyes. The reusability study exhibited ZnS/Ag has highly stable and degraded more than 80% of RR 120 under sunlight irradiation after 4th cycle.

Исследование каталитической и изомеризующей активности многокомпонентных скелетных никелевых катализаторов в реакции гидрирования гексена-1

In this work, the effect of the amount of catalyst, modifying additives, and the phase composition of the alloys on the catalytic and isomerizing activity of skeletal in the hydrogenation reaction of hexane-1 is investigated. It has been shown that for all studied catalysts, the yield of products in the processes of migration and isomerization depends very strongly on the weighed portion of the catalyst introduced into the reaction medium. So, for example, the yield of hexane-2 with an increase in the catalyst weight increases linearly to 0.5g of nickel, while at the initial stage of the reaction the yield of hexane-2 reaches 62%. With a further increase in the catalyst weight (up to 1 g of Ni), the yield of hexane-2 decreases. The results of chromatographic analysis indicate a high activity of modified skeletal nickel catalysts in the reaction of migration of -C = C- bonds during hydrogenation of hexene-1. Modification of Fe, Pd, Sn and Ag increases the migration coefficient (Kmigr) from 0.66 to 0.70-0.77, while additions of Ti, Mo, Ti-Mo and Zr practically do not change it. The activity of the catalyst increases with the introduction of the metals Cu, Zn, Pb, Ti-Mo, Mo, Bi, Ag, and Mo-Cu (W=120-290 cm3/min·g Ni) into the initial alloy, while the addition of Fe, Pd and Mn (W=56-80 cm3/min·g Ni), while the influence of the components Ti, Zr and Sn is insignificant (W=115-117 cm3/min·g Ni).

Silver-Modified Nano Mordenite for Carbonylation of Dimethyl Ether

Mordenite (H-MOR) catalysts were synthesized by a hydrothermal method, and silver-modified mordenite (Ag-MOR) catalysts were prepared by ion exchange with AgNO3 at different concentrations. The performance of these catalysts in the carbonylation of dimethyl ether (DME) to methyl acetate (MA) was also evaluated. The catalysts were characterized by Ar adsorption/desorption, XRD, ICP-AES, SEM, HRTEM, 27Al NMR, H2-TPR, NH3-TPD, Py-IR, and CO-TPD. According to the characterization results, Ag ion exchange sites were mainly located in the 8-membered ring (8-MR) channels of Ag-MOR; evenly dispersed Ag2O particles were also present. The acid site distribution was changed by the modification of Ag, and the amount of Brønsted acid sites increased in 8-MR and decreased in 12-MR. The CO adsorption performance of the catalyst significantly increased with the modification of Ag. These changes improved the conversion and selectivity of the carbonylation of DME. Over 4Ag-MOR in particular, DME conversion and MA selectivity reached 94% and 100%, respectively.

Enhanced visible light-driven photodegradation of rhodamine B by Ti3+ self-doped TiO2@Ag nanoparticles prepared using Ti vapor annealing

In recent years, Ti3+ self-doped TiO2 (B-TiO2) exhibits great potential as a photocatalyst. In this work, Ti vapor-assisted annealing is first demonstrated for Ti3+ doping and improving the visible absorption of TiO2. TEM results exhibit the formation of disordered layer, indicating the successful fabricating of B-TiO2. The absorption increase in TiO2 caused by Ti vapor annealing reaches nearly 50% in the visible wavelength range. Benefiting from the absorption increase, the photocatalytic performance of TiO2 after Ti vapor annealing increases by 60–70%. Surface modification of Ag onto B-TiO2 is also carried out to further improve its optical property. Ag-modified Ti3+ self-doped TiO2 (B-TiO2@Ag) exhibits great visible photodegradation behavior to RhB. The RhB degradation rate reaches 97.76% after 60 min of visible light irradiation. Electrochemical performance tests demonstrate that as-prepared TiO2@Ag has lower resistance than W-TiO2. The results indicate that B-TiO2@Ag has great potential in solar photocatalytic degradation of pollutant.

Glycerol Oxidation Reaction Mechanism on Ag-Modified Pt Electrode in Alkaline Medium

Introduction Recently, biodiesel fuel (BDF) attracts attention due to the progress of global warming. Glycerol as a byproduct is produced with BDF, and practically used for pharmaceuticals, cosmetics, food additives and so on. With the mass production of BDF, new applications of the glycerol byproduct need to be found. The application of glycerol as anode for direct alcohol fuel cells (DAFCs) can be an important solution because it has low toxicity and high specific energy (5.0 kWh kg-1). However, glycerol has two C-C bonds and three OH groups, so the mechanism for glycerol oxidation reaction (GOR) is complex,1 and the rate for GOR is so slow that the complete oxidation to CO2 is very difficult. Palladium is known to be one of active materials for GOR. We have found the alloy nanoparticles of Pd with Ag or Au improved the GOR activity and tolerance to the poisoning species on Pd nanoparticle in alkaline medium due to the electronic and bi-functional effects.2 Meanwhile, the Pt electrode had higher GOR activity than the Pd electrode in terms of the onset potential of GOR current, and Ag would improve the GOR activity of Pt. In this study, the effect of the modification with Ag on the GOR activity of a Pt substrate was evaluated by cyclic voltammetry (CV). Moreover, the mechanism for GOR on the Ag-modified Pt (Ag/Pt) electrode was discussed based on in situ infrared reflection absorption spectra at different potentials. Experimental The Ag/Pt electrode was prepared by underpotential deposition of Cu (Cu-upd) on a Pt substrate and the following galvanic replacement with Ag. The coverage of Ag (θ Ag) on the Pt substrate were calculated from the charge for H desorption before and after the Ag modification. The Ag/Pt electrodes with θ Ag = 0.8 and 0.5 were used in this study, which are denoted as Ag(0.8)/Pt and Ag(0.5)/Pt, respectively. The electrolytes were 1 M KOH or (1 M KOH + 0.5 M glycerol) solutions. Pt plate (1 cm × 1 cm) and a Hg/HgO electrode were used as counter and reference electrodes, respectively. In situ infrared reflection-absorption spectroscopy (IRAS) was used to qualitatively analyze the products of GOR on the Pt, Ag(0.8)/Pt and Ag(0.5)/Pt electrodes in alkaline solution. All electrochemical measurements were performed at room temperature. Results and Discussion The GOR activity for the Pt, Ag(0.8)/Pt and Ag(0.5)/Pt electrodes in alkaline medium was evaluated by CV (Fig. 1). Both Ag(0.8)/Pt and Ag(0.5)/Pt electrodes had twice higher current density and about 150 mV lower onset potential than the Pt substrate. This means that the enhancement of the GOR activity is caused by the modification of Ag atomic layers. Moreover, as θ Ag increased, a GOR wave was separated into two. The durability for GOR was evaluated by potentiostatic electrolysis for 60 min at -0.1 V and -0.3 V (vs. Hg/HgO). At -0.1 V, the durability for GOR was decreased in the order of Ag(0.5)/Pt > Pt > Ag(0.8)/Pt. On the other hand, at -0.3 V, the Ag(0.5)/Pt electrode still showed the best tolerance to the poisoning species, but the durability for GOR of Ag(0.5)/Pt was poorer than that of Pt. These results indicated that the modification of Ag on Pt improved the GOR activity and durability. IRAS gives us the information on the GOR mechanism. In the case of the Pt electrode, the mainly absorption band are observed at 1310 cm-1, 1335 cm-1, 1350 cm-1, 1385 cm-1 and 1575 cm-1 which can be attributed to glyceraldehyde or glycerate, dihydroxyacetone, hydroxypyruvate, symmetric and symmetric O-C-O stretching of carboxylate, respectively. At higher potentials, the absorption band at 1310 cm-1 was obviously observed. On the other hand, in the case of both Ag(0.8)/Pt and Ag(0.5)/Pt electrodes, the absorption band at 1335 cm-1 due to dihydroxyacetone was more obviously observed at -0.4 to -0.2 V, whereas at -0.2 to 0.1 V, the absorption band at 1310 and 1350 cm-1 was strengthen. This results indicate that the oxidation of primary and secondary OH groups depends on potential, and the secondary OH (-0.4 to -0.2 V) and the primary OH ( -0.1 V) are preferentially oxidized on the Ag modified Pt electrodes. Acknowledgement This work was partially supported by JSPS KAKENHI Grant Number 15H04162. References 1) M. Simoes et al., Appl. Catal. B: Environ., 93, 354 (2010).2) B. T. X. Lam et al., J. Power Sources, 297, 149 (2015). Figure 1

Modification of Ag nanoparticles/reduced graphene oxide nanocomposites with a small amount of Au for glycerol oxidation

The surface modification of Ag nanoparticles supported on reduced graphene oxide (RGO) with a small amount of Au and the activity of Au-modified Ag/RGO (Au–Ag/RGO) catalysts for the electrooxidation of glycerol have been investigated. The deposition of Au on Ag/RGO nanocomposites was performed electrochemically, and the Au–Ag/RGO catalysts with Au:Ag atomic ratios in a range from 1:303 to 1:43 were prepared. The characterization of catalysts reveals a partial coverage of the Ag nanoparticle surface by Au adatoms. Cyclic voltammetric measurements indicate that the Au–Ag/RGO catalysts show almost the same activity as Au/RGO in terms of the geometric surface area of glassy carbon substrates for glycerol oxidation in alkaline solution, while Ag/RGO shows no catalytic activity. The Au–Ag/RGO catalysts have great advantages over Au/RGO in terms of the Au mass specific activity. A significant improvement in the catalytic activity of Ag/RGO by the deposition of a small amount of Au and a high utilization of Au are achieved, and the result is of significance for preparing highly active catalysts at low cost by using less expensive metal and active metal.

Syntheses, single-crystal structures, vibrational spectra and DSC/TG analyses of orthorhombic and trigonal Ag[N(CN)2

Abstract Colorless powders of orthorhombic Ag[N(CN)2] were synthesized by blending aqueous solutions Ag[NO3] with stoichiometric amounts of Na[N(CN)2] equally dissolved in water. Single crystals of both modifications of Ag[N(CN)2] could be obtained by recrystallizing the powder with aqueous ammonia. Non-isothermal evaporation of the solvent at room temperature within a few hours yielded the orthorhombic modification as the main product crystallizing in the space group Pnma (no. 62) with the unit-cell parameters a = 1612.45(12), b = 361.58(3) and c = 599.02(4) pm (Z = 4). Upon evaporating the solvent much more slowly, isothermally within a few days, mainly thin hexagonal platelets of the trigonal modification of Ag[N(CN)2] were obtained, crystallizing in the space group P3121 (no. 152) with the lattice constants a = 359.86(3) and c = 2285.91(17) pm (Z = 3). Both results corroborate earlier structure determinations, but show higher precision. The vibrational spectra confirm the presence of the dicyanamide anion [N(CN)2]−, but exhibit slight differences to literature data. Differential scanning calorimetry/thermogravimetry (DSC/TG) analyses were performed to further characterize the two modifications.

Modification of Ag3VO4 with graphene-like MoS2 for enhanced visible-light photocatalytic property and stability

Graphene-like MoS2/Ag3VO4 composites exhibited remarkably enhanced photocatalytic activities for the photodegradation of dyes within a short time compared to pure Ag3VO4.

Cyclodehydration of diethylene glycol over Ag-modified Al2O3 catalyst

Vapor-phase cyclodehydration of diethylene glycol (DEG) into 1,4-dioxane (DOX) were performed over several solid acid catalysts, such as Al2O3, SiO2Al2O3, Beta and MFI zeolites. All the catalytic activity gradually decreased with time on stream, especially Beta and MFI zeolites with strong acidic property. The catalysts were modified with silver metal for stabilizing the catalytic activity: Al2O3 modified with 1wt.% Ag2O showed the best catalytic performance. Characterizations such as XRD, TPD and FTIR were performed for analyzing the carbonaceous compound deposited on the catalysts after reaction and investigating the effect of the addition of Ag2O onto Al2O3. Polyethylene glycol was proposed as the carbonaceous compound by FTIR analysis. The modification of Ag was found to decrease the averaged acid strength of Al2O3, which is supposed to be effective for inhibiting carbon deposition and stabilizing the catalytic activity. It was also found that H2, as a carrier gas, was indispensable for stabilizing the conversion of DEG into DOX. Silver metal would work as a remover of the product on the catalyst surface together with H2 to prevent carbon deposition. Over Al2O3 modified with 1wt.% Ag2O, a stable DOX selectivity of 90% with a complete conversion was achieved at 250°C and a contact time of 156.8ghmol−1.

Silver/titania nanocomposite-modified photoelectrodes for photoelectrocatalytic methanol oxidation

Silver deposited titania (Ag/TiO2) nanocomposite thin films were fabricated by the simple sonochemical deposition of Ag on preformed aerosol-assisted chemical vapor deposited TiO2 thin films. The photelectrocatalytic performance of a newly fabricated Ag/TiO2-modified photoelectrode was studied for methanol oxidation under simulated solar AM 1.5G irradiation (100 mW/cm2). The Ag/TiO2-modified photoelectrode showed a photocurrent density of 1 mA/cm2, which is four times that of an unmodified TiO2 photoelectrode. The modification of Ag on the TiO2 surface significantly enhanced the photoelectrocatalytic performance by improving the interfacial charge transfer processes, which minimized the charge recombination. Density functional theory (DFT) calculation studies revealed that methanol could be easily adsorbed onto the Ag surfaces of Ag/TiO2 via a partial electron transfer from Ag to methanol. The newly fabricated Ag/TiO2-modified photoelectrode could be a promising candidate for photoelectrochemical applications.

Improved electrochemical performance of Ag-modified Li4Ti5O12 anode material in a broad voltage window

Li4Ti5O12/Ag composites were synthesized by a solid-state method. The effect of Ag modification on the physical and electrochemical properties is discussed by the characterizations of X-ray diffraction, scanning electron microscopy, cyclic voltammetry, electrochemical impedance spectroscopy, cycling and rate tests. The lattice parameter of Li4Ti5O12 with a low Ag content is almost not changed, but the lattice parameter becomes larger due to the high content of Ag. Li4Ti5O12/Ag material has a uniform particle size which is about 1 \(\upmu\)m. Modification of appropriate Ag is beneficial to the reversible intercalation and deintercalation of Li + . Modification of Ag not only decreases the charge transfer resistance of Li4Ti5O12 material, but also improves the diffusion coefficient of lithium ion. Li4Ti5O12/Ag (3 mass%) material has the lowest charge transfer resistance, the highest diffusion coefficient of lithium ion and the best rate cycling performance. Li4Ti5O12/Ag composites were synthesized by a solid-state method, and the remarkably improved rate properties of the Ag-modified samples are due to high conductivity of Ag at the surface of Li4Ti5O12, and faster kinetics of both the Li+ diffusion and the charge transfer reaction.

Posttranslational Modification of Gluten Shapes TCR Usage in Celiac Disease

Posttranslational modification of Ag is implicated in several autoimmune diseases. In celiac disease, a cereal gluten-induced enteropathy with several autoimmune features, T cell recognition of the gluten Ag is heavily dependent on the posttranslational conversion of Gln to Glu residues. Evidence suggests that the enhanced recognition of deamidated gluten peptides results from improved peptide binding to the MHC and TCR interaction with the peptide-MHC complex. In this study, we report that there is a biased usage of TCR Vβ6.7 chain among TCRs reactive to the immunodominant DQ2-α-II gliadin epitope. We isolated Vβ6.7 and DQ2-αII tetramer-positive CD4(+) T cells from peripheral blood of gluten-challenged celiac patients and sequenced the TCRs of a large number of single T cells. TCR sequence analysis revealed in vivo clonal expansion, convergent recombination, semipublic response, and the notable conservation of a non-germline-encoded Arg residue in the CDR3β loop. Functional testing of a prototype DQ2-α-II-reactive TCR by analysis of TCR transfectants and soluble single-chain TCRs indicate that the deamidated residue in the DQ2-α-II peptide poses constraints on the TCR structure in which the conserved Arg residue is a critical element. The findings have implications for understanding T cell responses to posttranslationally modified Ags.

Modification of Ag–PVP nanocomposites by gamma irradiation

Ag–PVP (silver-polyvinylpyrrolidone) films were spin-coated on silica substrates from Ag–PVP colloidal solution. Formation of nanoparticles in deposited films was achieved by photoreduction of silver ions due to UV irradiation of prepared samples. Presence of spherical nanoparticles in UV irradiated samples was identified according to the measured absorbance peaks of samples that were observed in the range 410–430 nm and were explained by surface plasmon resonance phenomenon. Produced nanocomposite films were further on modified additionally irradiating them with gamma photons within the dose range (2–50) Gy. Plasmonic and mechanical properties of gamma irradiated nanocomposite films have been investigated by UV–vis spectroscopy and AFM and compared to those obtained after prolonged UV irradiation of films.

Modification of Ag-doped BaTiO 3 powders through La gaseous penetration route

The Ag-doped BaTiO 3 (BATO) polycrystalline powders were fabricated by Sol-Gel method. Further modification by rare earth La was done through gaseous penetration route. Changes in constitution, structure, and electrical conductivity before and after modification of Ag and La were characterized. The acceptor dopant Ag owned the ability to decrease the resistivity of the doping samples from 4.30×10 9 Ω·m to 6.14×10 5 Ω·m where the resistivity fell by 4 orders of magnitude when the Ag doping ratio was 0.10%. And more doping of Ag enhanced the resistivity dramatically even beyond 2.0×10 7 Ω·m. Yet, gaseous penetration of La successively reduced the resistivity of BATO to the lowest point of 2.45×10 5 Ω·m. XRD analysis indicated that the doping process of Ag did not change the perovskite structure and main phases of the powders. However, new compound BaLa 2O 4 generated from complex reactions during the penetration process, which manifested that La 3+ penetrated into the crystal lattices in the form of substituting the Ti 4+ site. And this substitution strengthened the Ti-O bond, which led to the inhibition of blue shift in FTIR spectrum caused by doping of Ag. The morphology of La penetrated BATO powders detected by SEM and EDAX suggested that La did penetrate into the powders and this penetration process progressed the partly sintering of the powders which is in favor of the conductivity.