Amount Of Ag Research Articles

Influence of silver introduction into (Ag,Cu)(In,Ga)S2 thin films on their physical properties

Silver was introduced into pure-sulfide Cu(In,Ga)S2 (CIGS) to form (Ag,Cu)(In,Ga)S2 (ACIGS) compound. The impact of the Ag addition on physical properties and photovoltaic performances was therefore examined to determine suitable Ag amount in ACIGS solar cells. The ACIGS thin films with different Ag/(Ag + Cu) (AAC) compositional ratios were formed through the sulfurization of the In/Cu/Ga/Ag stacked precursors. It is disclosed that the AAC is obviously increased from 0 to 0.18 under the increase in the Ag precursor thickness from 0 to 80 nm. Moreover, under the suitable Ag introduction (ACC of 0.04), the quality of ACIGS absorbers is improved with low Urbach energy (EU) and the enlargement of crystal grain size. The decreased conduction band offset between the absorber and CdS buffer layers under Ag addition is realized with lower valence band maximum value of the ACIGS absorbers, thus feasibly increasing the hole barrier. Additionally, the band alignment between absorber and CdS buffer layers was disclosed with the varied ACC based on photoemission yield spectroscopy. Ultimately, the short-circuit current density of the ACIGS solar cell is clearly increased by 2 mA/cm2 under suitable ACC of 0.04.

An environmentally friendly bifunctional composite mediated by metal organic frameworks for dramatically enhanced SERS and photocatalytic performances

The portable materials with excellent bi-functionality used in monitoring and photocatalytic degradation of organic contaminants are significant in light energy utilization and sustainability. Herein, a plug and play and cost-efficient Ti-TiO2-ZIF-8-Ag (ET-Z8-Ag) composite was facilely fabricated. It showed that the etched titanium sheet was conducive to the growths of the zeolitic imidazolate framework-8 (ZIF-8) and Ag with good dispersion. Furthermore, the SERS and photocatalytic performances of the ET-Z8-Ag were studied with p-aminothiophenol (p-ATP, a harmful pesticide intermediate) as the analyte. It showed that more p-ATP molecules can be adsorbed as a result of the π-π interaction and Ag-S bond between p-ATP and the ET-Z8-Ag. Moreover, the large and special heterogeneous interface in the ET-Z8-Ag was advantageous to promoting charge transfer, and thus SERS response and photocatalytic degradation of p-ATP were improved. Compared with some materials reported, the ET-Z8-Ag with a smaller amount of Ag showed higher sensitivity and faster degradation rate towards p-ATP. Especially, almost 100% p-ATP in river water can be rapidly removed within 5 min with the help of the ET-Z8-Ag, and its efficiency was still remained after six cycles. The cost-efficient and portable composite will be potential in the detection and removal of organic pollutants in wastewater.

Controlled release of Ag+ ions to human cancer cells selectively neutralized with silver nanoparticles of different sizes produced by a green synthesis method

We present a facile green method to synthesize silver nanoparticles (AgNPs) with different sizes and uniform size distributions using an extract of Rhododendron mucronulatum flowers. Here, AgNPs were utilized to modify the release of Ag+ ions and selectively annihilate human cancer cells. AgNPs were prepared at ambient temperature (RT-AgNPs) and in higher-temperature water baths at 60 °C (W60-AgNPs) and 70 °C (W70-AgNPs) to modify the diameter and uniformity of the AgNPs. The W60-AgNPs were further treated with acid to modify their size and surface state (named AW60-AgNPs). The water-bath technique enabled an alteration of the relative rates of initial nucleation and growth of nanoparticles in a homogeneous environment, promoting the creation of small AgNPs with a uniform diameter distribution. The acid treatment eroded the surface particles to reduce their diameter and simultaneously introduced functional groups. The Ag+-ion release efficiency of the prepared nanoparticles and the toxicity of Ag+ ions on cancer cells were examined. Among the prepared samples, the AW60-AgNPs released the greatest amount of Ag+ ions and produced the largest amount of reactive oxygen species (O2̇−, ˙OH, and H2O2). All of the AgNP samples were applied to tumor cells (K562 and HT1080) and healthy cells (LO2) in vitro. In the presence of K562 cells, AW60-AgNPs showed the most efficient dose- and time-dependent early and late apoptosis as well as reduced viability. A crystal violet assay showed that the synthesized particles preferentially attack HT1080 cancer cells rather than LO2 normal cells. We found that Ag+ ions release efficiency and selectivity varied with particle size, and that DNA damage in tumor cells was due to the formation of Ag+-coordinated complexes within DNA base pairs.

Toward understanding the effects of solution heat treatment, Ag addition, and simultaneous Ag and Cu addition on the microstructure, mechanical properties, and corrosion behavior of the biodegradable Mg–2Zn alloy

In this study, the effects of adding silver (0.2 and 0.6 wt%) and copper (0.1 wt%) antibacterial elements, on the microstructure, mechanical properties, and degradation behavior of the as-cast Mg–2Zn alloy were investigated. The obtained results indicate that both Ag and Cu showed significant grain refinement effects in the as-cast condition. The MgZn precipitates were formed in the as-cast Mg–2Zn–0.2Ag alloy, which contained a small amount of Ag. Increasing the Ag content to 0.6 wt% resulted in formation of the Mg54Ag17 phase. Simultaneous addition of 0.2 wt% Ag and 0.1 wt% Cu to the Mg–2Zn alloy caused the ternary Mg(Zn,Cu) precipitates to form. Solution-treated Mg–2Zn and Mg–2Zn–0.6Ag alloys had a single-phase microstructure, while some Mg(Zn,Cu) precipitates remained in the Mg–2Zn–0.2Ag–0.1Cu alloy after solution treatment. Shear punch test showed 15, 12, and 23% increases in ultimate shear strength values of the as-cast Mg–2Zn–0.2Ag, Mg–2Zn–0.6Ag, and Mg–2Zn–0.2Ag–0.1Cu alloys compared to the Mg–2Zn alloy, respectively. The hydrogen evolution rate of the as-cast Mg–2Zn–0.2Ag, Mg–2Zn–0.6Ag, and Mg–2Zn–0.2Ag–0.1Cu alloys were found to be 38, 90 and 70% higher than the as-cast Mg–2Zn alloy, respectively. However, the solution treatment reduced the degradation rate significantly. Hence, it was found in this investigation that adding Ag and Cu elements would be so effective for improving different properties of the Mg–Zn alloys by using appropriate solution heat treatment.

NK cells in peripheral blood carry trogocytosed tumor antigens from solid cancer cells.

The innate immune lymphocyte lineage natural killer (NK) cell infiltrates tumor environment where it can recognize and eliminate tumor cells. NK cell tumor infiltration is linked to patient prognosis. However, it is unknown if some of these antitumor NK cells leave the tumor environment. In blood-borne cancers, NK cells that have interacted with leukemic cells are recognized by the co-expression of two CD45 isoforms (CD45RARO cells) and/or the plasma membrane presence of tumor antigens (Ag), which NK cells acquire by trogocytosis. We evaluated solid tumor Ag uptake by trogocytosis on NK cells by performing co-cultures in vitro. We analyzed NK population subsets by unsupervised dimensional reduction techniques in blood samples from breast tumor (BC) patients and healthy donors (HD). We confirmed that NK cells perform trogocytosis from solid cancer cells in vitro. The extent of trogocytosis depends on the target cell and the antigen, but not on the amount of Ag expressed by the target cell or the sensitivity to NK cell killing. We identified by FlowSOM (Self-Organizing Maps) several NK cell clusters differentially abundant between BC patients and HD, including anti-tumor NK subsets with phenotype CD45RARO+CD107a+. These analyses showed that bona-fide NK cells that have degranulated were increased in patients and, additionally, these NK cells exhibit trogocytosis of solid tumor Ag on their surface. However, the frequency of NK cells that have trogocytosed is very low and much lower than that found in hematological cancer patients, suggesting that the number of NK cells that exit the tumor environment is scarce. To our knowledge, this is the first report describing the presence of solid tumor markers on circulating NK subsets from breast tumor patients. This NK cell immune profiling could lead to generate novel strategies to complement established therapies for BC patients or to the use of peripheral blood NK cells in the theranostic of solid cancer patients after treatment.

Microstructure of CeO2 Nanoparticles Loaded with Different Amounts of Ag and Their Antimicrobial Activity.

Microstructure of CeO2 Nanoparticles Loaded with Different Amounts of Ag and Their Antimicrobial Activity.

Synthesis of Biocompatible Silver-Doped Carbonate Hydroxyapatite Nanoparticles Using Microwave-Assisted Precipitation and In Vitro Studies for the Prevention of Peri-Implantitis.

A carbonate-hydroxyapatite-based antibacterial implant material with low cytotoxicity was synthesized. The silver ion (Ag+) was incorporated into CHA material, resulting in silver-doped carbonate hydroxyapatite (CHA-Ag). The microwave-assisted precipitation method was used to synthesize the CHA-Ag material. The amount of Ag+ was varied at 0.005, 0.010, and 0.015 mol fractions (χAg). The XRD results showed that the diffractograms corresponded with hydroxyapatite (ICSD 98-05-1414), without any additional phase. The presence of carbonate ions was indicated by vibrations at wavenumber of 871, 1411, and 1466 cm-1 in the infrared spectra. The CHA-Ag materials were agglomerates of nanosized particles with low crystallinity. The particle size and crystallinity of the materials decreased due to the incorporation of CO32- and Ag+. The incorporated Ag+ successfully inhibited peri-implant-associated bacterial growth. The antibacterial ability increased alongside the increase in the Ag+ amount. The pre-osteoblast MC3T3E1 cell could grow up to >70% in the MTT assay, despite the use of Ag+ as a dopant. The cell viability was higher in the CHA-Ag-containing media than in the CHA-containing media. The MTT assay also revealed that the CHA-Ag cytotoxicity decreased even though the Ag+ amount increased. The CHA-Ag-15 had the lowest cytotoxicity and highest antibacterial activity. Therefore, the optimal amount of Ag+ in the CHA-Ag formulation was χAg = 0.015.

Silver and copper nanoparticles: Lower concentration controlled thermal decomposition of their salt precursors

Generally, salt precursors have been investigated for the production of nanoparticles with semiconducting properties such as metal chalcogenides and others. They have demonstrated excellent features for the ease of converting them to nanoparticles. Thermal decomposition and solvothermal processes are often followed to produce particles with stabilizers of varied ranges of size with improved size control dependent on the set collective conditions and the intended applications. In this study, silver (Ag) and copper (Cu) nanoparticles were synthesized using the thermal decomposition method in the presence of oleylamine as a capping agent in order to produce good stable uniform monodispersed nanoparticles. Lower amounts of Ag and Cu precursors (0.1 - 0.2 g) were used to study their effect on the size and morphology of the nanoparticles. The synthesized nanoparticles under various conditions were characterized using UV/Vis and PL spectroscopy, TEM, and XRD. It was observed that an increase in the precursor concentration led to an increase in particle size with varying morphologies for both Ag and Cu nanoparticles. The TEM images of Ag nanoparticles showed that uniform morphology and spherical shape were observed with narrow diameters ranging from 5.9 to 6.8 nm. However, for Cu nanoparticles, uniform morphology and spherical shape were only observed at a precursor concentration of 0.15 g with an average diameter of 7.8 nm. The XRD results of both Ag and Cu nanoparticles showed peaks that were identified as Ag and Cu in the face-centred cubic.

Magmatic–Hydrothermal Transport of Metals at Arc Plutonic Roots: Insights from the Ildeus Mafic–Ultramafic Complex, Stanovoy Suture Zone (Russian Far East)

The Ildeus mafic–ultramafic complex represents plutonic roots of a Triassic magmatic arc tectonically emplaced into the thickened uppermost crust beneath the Mesozoic Stanovoy collided margin. The mafic–ultramafic complex cumulates host Ni-Co-Cu-Pt-Ag-Au sulfide-native metal-alloy mineralization produced through magmatic differentiation of subduction-related primary mafic melt. This melt was sourced in the metal-rich sub-arc mantle wedge hybridized by reduced high-temperature H-S-Cl fluids and slab/sediment-derived siliceous melts carrying significant amounts of Pt, W, Au, Ag, Cu and Zn. Plutonic rocks experienced a pervasive later-stage metasomatic upgrade of the primary sulfide–native metal–alloy assemblage in the presence of oxidized hydrothermal fluid enriched in sulfate and chlorine. The new metasomatic assemblage formed in a shallow epithermal environment in the collided crust includes native gold, Ag-Au, Cu-Ag and Cu-Ag-Au alloys, heazlewoodite, digenite, chalcocite, cassiterite, galena, sphalerite, acanthite, composite Cu-Zn-Pb-Fe sulfides, Sb-As-Se sulfosalts and Pb-Ag tellurides. A two-stage model for magmatic–hydrothermal transport of some siderophile (W, Pt, Au) and chalcophile (Cu, Zn, Ag) metals in subduction–collision environments is proposed.

Significant reduction of thermomagnetic hysteresis in NdMn2-x Ag x Si2 (0 ≤ x ≤ 0.4) alloys

ABSTRACT In this research, the single-phase tetragon NdMn2-x Ag x Si2 (0 ≤ x ≤ 0.4) alloys were prepared. It was found that the phase transition temperature was decreased by evaluating Ag substitution, which was attributed to the enhancement of orbital hybridization. The thermomagnetic hysteresis disappears for x ≥ 0.2. For Δμ0H of 0–7 T, the values of the maximum magnetic entropy change (the relative cooling power) are 22.2 J/kgK (420.7 J/kg), 20.1 J/kgK (500.5 J/kg), 19.9 J/kgK (552.8 J/kg) and 12.0 J/kgK (300.0 J/kg) in NdMn2-x Ag x Si2 (x = 0, 0.2, 0.3 and 0.4) alloys. The XPS valence band spectra indicate that the density of electron and the hybridization effect is enhanced by increasing the substitution amount of Ag. This is attributed to the fact that the atomic radius of Ag is larger than that of Mn, resulting in the strengthening of the covalent bond between Ag and Si.

Antibacterial AgNPs-PAAm-CS-PVP nanocomposite hydrogel coating for urinary catheters

Catheter-associated urinary tract infections (CAUTI) account for 40% of all hospital-acquired infections and more than 1 million CAUTIs occur annually in the United States and Europe with increased morbidity and mortality. Although anti-bacterial coating is an effective way to solve this problem, so far only limitted progress has been made. In this paper we prepared a novel antibacterial silver nanoparticles poly(acrylamide)-chitosan-polyvinylpyrrolidone (AgNPs-PAAm-CS-PVP) composite hydrogel coating on latex urinary catheters by a simple dipping method. The average particle size, the size distribution as well as the polydispersity index (PDI) value of the AgNPs were examined by using TEM analysis. The surface morphology and roughness, the element contents, the functional groups, the static contact angles, and the surface energy of the coatings were characterized by using SEM, EDS, AFM, FTIR, XPS, and a video optical contact angle instrument, respectively. The amount of the total Ag released from the hydrogel was tested by ICP-MS. The antibacterial and antiadhesion efficacies against Gram-negative E. coli of the coated urinary catheters were evaluated with an inhibition zone test and fluorescence microscopy. A synergistic antibacterial mechanism of AgNPs and CS was also presented. The results showed that the synthesized AgNPs in the hydrogel had a spherical shape with an average diameter of 25.9 nm. The AgNPs-PAAm-CS-PVP hydrogel had a more durable release of the antibacterial agents of AgNPs and Ag+, which explains why the coated urinary catheters had long-term antibacterial activity. The mathematical modelling of Ag release kinetics supported Case I or Fickian diffusion mechanism for the AgNPs-PAAm-CS-PVP hydrogel. The hydrogel-coated urinary catheters became smoother and more hydrophilic which further explains why the coated urinary catheter decreased bacterial adhesion. More importantly, bacterial activity and bacterial adhesion assays showed that both the outer and inner surfaces of the AgNPs-PAAm-CS-PVP hydrogel-coated urinary catheters had strong antibacterial property against E. coli. Furthermore, the hydrogel-coated urinary catheters showed high hemocompatibility and cytocompatibility for promising biomedical applications. The AgNPs-PAAm-CS-PVP hydrogel-coated urinary catheters have great potential for decreasing CAUTIs.

Influence of Coating a TiO2 Electrode with DN-F05 and DN-F05-Ag on the Photovoltaic Performance of DSSC Solar Cells

A DSSC’s performance depends on its working electrode. Since this working electrode functions as an electron carrier, it affects how well DSSC solar cells perform. This study focused on working electrodes that use the dye DN-F05 and the Ag ions in the hybrid dye DN-F05 as a sensitizer. This research was conducted using the spin-coating method. Based on structural, optical, and electrical data, the results obtained were related to each other. It was determined that Ag has a significant influence on DSSC performance, and this discovery was also the main goal of this study. Previous studies have shown that the addition of Ag as a doping agent is an effective strategy for improving chemical and electronic properties. This can be proven through electrical measurements, which have shown an efficiency of 5.33%. However, when a significant amount of Ag is hybridized in the dye DN-F05, it will cause a decrease in DSSC performance due to the accumulation of Ag particles on the semiconductor’s surface, creating a barrier to light absorption and aggregation. This is what led to the selection of a hybrid material (Ag metal), as Ag is unique and offers great potential with respect to boosting solar cells’ performance.

Periodontal status following orthodontic mini-screw insertion: A prospective clinical split-mouth study.

Anchorage control is one of the most important determinants of orthodontic treatments. Mini-screws are used to achieve the desired anchorage. Despite all their advantages, there is a possibility that treatment will not be successful due to conditions related to their interaction with the periodontal tissue. To evaluate the status of the periodontal tissue at the sites adjacent to the orthodontic mini-implants. A total of 34 teeth (17 case and 17 control) in 17 orthodontic patients requiring a mini-screw in the buccal area to proceed with their treatment were included in the study. Oral health instruction was provided to the patients prior to the intervention. In addition, scaling and root planing of the root surface were done using manual instruments and ultrasonic instruments if needed. For tooth anchorage, a mini-screw with Elastic Chain or Coil Spring was used. The following periodontal indices were examined in the mini-screw receiving tooth and the contralateral tooth: plaque index, pocket probing depth, attached gingiva level (AG), and gingival index. Measurements were made before the placement of the mini-screws and 1, 2, and 3 months following that. The results revealed a significant difference only in the amount of AG between the tooth with mini-screw and the control tooth (p = 0.028); for other periodontal indices, there were no significant differences between the two groups. This study showed that periodontal indices in adjacent teeth of the mini-screws do not change significantly compared to other teeth and mini-screws can be used as a suitable anchorage without posing a threat to the periodontal health. Using mini-screws is a safe intervention for orthodontic treatments.

High‐Performance Silver‐Doped Porous CuBi2O4 Photocathode Integrated with NiO Hole‐Selective Layer for Improved Photoelectrochemical Water Splitting

AbstractCuBi2O4(CBO) has received considerable attention owing to its ideal optical bandgap and positive photocurrent onset potential. However, CBO photocathodes exhibit poor charge carrier separation and transfer across the conducting substrate interface. Herein, a systematic incorporation of Ag+‐cations into nanosized porous CBO network (ACBO) using a simple pulsed‐electrodeposition method. In ACBO photocathode, the Ag+‐ions replace the Bi3+‐ions, thereby building an increased hole concentration, which further signifies the photogenerated electron‐hole separation. Additionally, introducing a low‐cost NiO hole‐selective layer between ACBO and the conducting substrate enables a back‐interface‐aided hole‐extraction and electron blocking, resulting in an improved charge transfer across the back interface. Compared with an unmodified CBO, the NiO/ACBO photocathode exhibits a three‐fold enhanced photocurrent performance. This enhances the photocurrent originating from the incorporation of a substantial amount of Ag+‐ions into the CBO structure, leading to an increased acceptor density as well as the formation of an appropriate hole‐selective layer across the back‐contact. The absorption percentage, time‐resolved photoluminescence, and photoelectrochemical impedance spectroscopy measurements unveil the potential light harvesting, charge separation, and transfer characteristics of the NACBO photoelectrode, respectively. Through this systematic study, an efficient and simple strategy is determined for developing ternary metal oxide‐based photocathode/photoanode systems for sustainable energy applications.

Co-optimization of Ag and K doping to regulate room-temperature coefficient of resistivity of La0.7Ag0.3-xKxMnO3 films

In this study, La0.7Ag0.3-xKxMnO3 (LAKMO, x = 0.15, 0.16, 0.17, 0.18, and 0.19) films with excellent electrical properties and low surface roughness were prepared on SrTiO3 (001) substrates using the spin-coating method. The crystal structures and ion valence states of the LAKMO films were modified by adjusting the doping amounts of Ag and K. The Jahn–Teller effect and electron–lattice coupling were enhanced with the MnO6 octahedron undergoes distortion. Moreover, the double-exchange interaction was improved with an increase in the number of Mn4+/Mn3+ ion pairs. Under the influence of these factors, the electrical transport properties especially the temperature coefficient of resistivity (TCR) of the LAKMO films can be refined modulated or optimized via A-site Ag and K co-doping. When x = 0.17, the maximum TCR of LAKMO reached 11.23 % K−1 at 293.23 K. Thus, La0.7Ag0.13K0.17MnO3 film with a large TCR exhibited excellent thermal properties at room temperature and was considered material for application to uncooled infrared bolometers.

VOC‐losses across the band gap: Insights from a high‐throughput inline process for CIGS solar cells

AbstractBig sets of experimental data are key to assess statistical device performance and to distill underlying trends. This insight, in turn, can then be used to improve on the fabrication process. We here describe a standardized and optimized inline fabrication process and present a statistical analysis of tens of thousands of cells with chalcopyrite‐type Cu(In,Ga)Se2 absorber. The large number of samples allows us to point out where Ag alloying into the absorber offers improvements, and how it couples with compositional and optoelectronic properties. Solar cell parameters as a function of chemical composition of the absorber highlight the importance of fill factor on overall cell performance. Finally, we calculate losses in open‐circuit voltage as a function of band gap energy and show that radiative losses can be reduced by increasing the amount of Cu and/or Ag.

In-situ electrodeposited Ag/Cu for electrochemical reduction of acetic acid to nanodiamond under ambient conditions

Carbon nanostructured materials such as nanodiamonds and graphene are useful for various applications, but their low-energy production technologies remain an important challenge to overcome. Herein, the electrochemical reduction of acetic acid using in-situ electrodeposited Ag/Cu to nanocrystalline carbon products was investigated as a function of AgNO3 concentrations in the presence of water and [BMIM]+[BF4]- ionic liquid. Under the conditions used, the deposited Ag clusters could become negatively charged and were responsible for the reduction of acetic acid and the consequent crystalline carbon growth. Increasing Ag concentrations did not only result in higher amounts of Ag being deposited but also created significant local pressure on the atomistic level, where the crystalline carbon was formed, resulting in the re-ordering of carbon atoms into nanodiamond structure. The presence of nanodiamond with average crystallite size 27 nm was clearly evidenced by XRD, Raman, XPS, and TEM-EDX-SAED. The in-situ electrochemical reduction has shown to be an effective ultra-low energy strategy to produce crystalline solid carbon under ambient conditions.

Persistence of Silver Nanoparticles Sorbed on Fresh-Cut Lettuce during Flume Washing and Centrifugal Drying

Increased agricultural use of silver nanoparticles (Ag NPs) may potentially lead to residual levels on fresh produce, raising food safety and public health concerns. However, the ability of typical washing practices to remove Ag NPs from fresh produce is poorly understood. This study investigated the removal of Ag NPs from Ag NP-contaminated lettuce during bench-top and pilot-scale washing and drying. Ag NP removal was first assessed by washing lettuce leaves in a 4-L carboy batch system using water containing chlorine (100 mg/L) or peroxyacetic acid (80 mg/L) with and without a 2.5% organic load and water alone as the control. Overall, these treatments removed only 3–7% of the sorbed Ag from the lettuce. Thereafter, Ag NP-contaminated lettuce leaves were flume-washed for 90 s in a pilot-scale processing line using ∼600 L of recirculating water with or without a chlorine-based sanitizer (100 mg/L) and then centrifugally dried. After processing, only 0.3–3% of the sorbed Ag was removed, probably due to the strong binding of Ag with plant organic materials. Centrifugation only removed a minor amount of Ag as compared to flume washing. However, the Ag concentration in the ∼750 mL of centrifugation water was much higher as compared to the flume water, suggesting that the centrifugation water would be preferred when assessing fresh-cut leafy greens for Ag contamination. These findings indicate that Ag NPs may persist on contaminated leafy greens with commercial flume washing systems unable to substantially reduce Ag NP levels.

A Basic Research for Conquest Drawbacks and Further Improvement of Properties of Heterogeneous-Nano Structured Copper Alloys

Changes in the microstructure and various properties of heavily cold-rolled Cu–Zn system alloys with small amounts of Ag were systematically investigated. While a typical heterogeneous (HN) was evolved in all the alloys, the texture and ratio of the microstructural components developed were slightly varied depending on the added amount of Ag and Zn. The characteristic “eye”-shaped twin domains tended to evolve more significantly with increasing addition of these elements. Thermal stability of the HN structure appeared to be improved by Ag addition. This was due to grain-boundary segregation (GBS) of Ag, which enabled sufficient age hardening. The GBS in the HN structure also resulted in the improvement of electrical conductivity. In this way, all the alloys showed quite high-tensile strength over 900 MPa along transvers direction with superior electrical conductivity around or over 30% IACS. Maximum tensile strength achieved was 990 MPa with 34.5% IACS for Cu–30mass%Zn–1 mass%Ag alloy.

Antigen Delivery Systems: Past, Present, and Future.

The COVID-19 pandemic has increased demand for safe and effective vaccines. Research to develop vaccines against diseases including Middle East respiratory syndrome, Ebolavirus, human immunodeficiency virus, and various cancers would also contribute to global well-being. For successful vaccine development, the advancement of technologies such as antigen (Ag) screening, Ag delivery systems and adjuvants, and manufacturing processes is essential. Ag delivery systems are required not only to deliver a sufficient amount of Ag for vaccination, but also to enhance immune response. In addition, Ag types and their delivery systems determine the manufacturing processes of the vaccine product. Here, we analyze the characteristics of various Ag delivery systems: plasmids, viral vectors, bacterial vectors, nanoparticles, self-assembled particles, natural and artificial cells, and extracellular vesicles. This review provides insight into the current vaccine landscape and highlights promising avenues of research for the development and improvement of Ag delivery systems.