Tuning the Piezoelectric Performance of K0.5Na0.5NbO3 through Li Doping: Insights from Structural, Elastic and Electronic Analyses.

The structural, elastic, piezoelectric, and electronic properties of Li-doped K0.5Na0.5NbO3 (K0.5-xNa0.5-yLix+yNbO3, KNN-L) are calculated. The properties of KNN-L are related to the Li-doping content and the replaced K or Na atoms. The bulk modulus, the shear modulus, and Young's modulus of KNN-L are mostly higher than those of KNN, and the hardness value increases. The Poisson ratio of KNN-L is lower than that of most KNN, and the ductility is reduced. All doped structures are direct band gap semiconductors. K0.5Na0.375Li0.125NbO3 has the largest piezoelectric charge constant, d33 = 44.72 pC/N, in the respective structures, which is 1.5 fold that of K0.5Na0.5NbO3 (29.15 pC/N). The excellent piezoelectric performance of Li-doping KNN-L was analyzed from the insights of elastic and electronic properties.

Modifying Surface Termination by Bidentate Chelating Strategy Enables 13.77% Efficient Kesterite Solar Cells.

Surfaces display discontinuities in the kesterite-based polycrystalline films can produce large defect densities, including strained and dangling bonds. These physical defects tend to introduce electronic defects and surface states, which can greatly promote nonradiative recombination of electron-hole pairs and damage device performance. Here, an effective chelation strategy is reported to suppress these harmful physical defects related to unterminated Cu, Zn, and Sn sites by modifying the surface of Cu2ZnSn(S,Se)4 (CZTSSe) films with sodium diethyldithiocarbamate (NaDDTC). The conjoint theoretical calculations and experimental results reveal that the NaDDTC molecules can be coordinate to surface metal sites of CZTSSe films via robust bidentate chelating interactions, effectively reducing surface undercoordinated defects and passivating the electron trap states. Consequently, the solar cell efficiency of the NaDDTC-treated device is increased to as high as 13.77% under 100 mW cm-2 illumination, with significant improvement in fill factor and open-circuit voltage. This surface chelation strategy provides strong surface termination and defect passivation for further development and application of kesterite-based photovoltaics.

Multi-dimensional plasmonic coupling system for efficient enrichment and ultrasensitive label-free SERS detection of bilirubin based on graphene oxide-Au nanostars and Au@Ag nanoparticles.

Rapid and sensitive detection of free bilirubin (BR) is essential for early diagnosis of jaundice and other hepatobiliary diseases. Inspired by sandwich immunoassay strategy, a multi-dimensional plasmonic coupling SERS platform composed of graphene oxide-Au nanostars nanocomposites (GANS NCs) and Au@Ag nanoparticles (NPs) was designed for label-free detection of BR. Specifically, GANS NCs were first prepared, and their excellent SERS activity was ascribed to synergistic enhancement effect of electromagnetic enhancement and chemical enhancement. Furthermore, SERS spectroscopy was used to monitor the adsorption process of BR. Subsequently, secondary reinforcing Au@Ag NPs were directly added, ultimately resulting in a multi-dimensional plasmonic coupling effect. The SERS enhancing mechanism of coupled system was discussed through electromagnetic field simulations. Interestingly, the high-density hotspots generated by strong plasmonic coupling in GANS-Au@Ag substrate could lead to more extraordinary SERS enhancing behavior compared to GANS NCs. Sensing efficiency of the SERS platform was examined by BR with a detection limit down to 10-11 M. Besides, GANS-Au@Ag NCs performed high uniformity and reproducibility. This work not only opens up a new avenue for construction of multi-dimensional plasmonic coupling system, but also offers a new biosensing technology for label-free diagnosis of BR-related diseases, thereby expecting to be applied in clinical diagnosis.

Further Boosting Solar Cell Performance via Bandgap-Graded Ag Doping in Cu2ZnSn(S,Se)4 Solar Cells Compared to Uniform Ag Doping.

Cu2ZnSn(S,Se)4 (CZTSSe) is a hopeful substitution to commercialized Cu(In,Ga)Se2 (CIGSe) devices with similar structure and optoelectronic properties and has advantages of nontoxicity, low cost, and abundant reserves. However, the traditional flat bandgap structure of the CZTSSe absorber layer does not efficiently enhance the collection of photogenerated electrons and decrease recombination. Graded bandgap engineering toward the interfaces of CIGSe solar cells is the key to realize high-efficiency devices. In this study, we obtained (Cu1-xAgx)2ZnSn(S,Se)4 (CAZTSSe) absorber layers with high-concentration Ag doping at both ends of the absorption layer and undoped or low-concentration Ag doping in the middle part through a new miscible layered precursor method. This bandgap structure suppressed CuZn defects, delayed Fermi level pinning near the CZTSSe/CdS interface, sustained good electrical conductivity and light absorption in the middle of the absorption layer, improved the conversion efficiency of incident light, and inhibited recombination of carriers toward the Mo back electrode. In addition, we also compared the performance of undoped, uniformly Ag-doped, and V-type Ag-doped CZTSSe devices to acquire a deeper understanding of the reasons for the enhanced performance. It can be found that compared with undoping, the open-circuit voltage (Voc) of the best devices with uniform doping (x = 15%) increased from 379 to 386 mV, the fill factor (FF) increased from 44.70 to 54.14%, and the photoelectric conversion efficiency (PCE) increased from 4.63 to 6.21%. More surprisingly, the Voc of the optimal CAZTSSe devices (sample D) with Ag-graded doping was increased to 413 mV and the FF was increased to 59.63%. It also achieved an impressive PCE of 7.35%. The above results prove the importance of tuning Ag gradient doping of CZTSSe films for improving solar cell performance.

Ultrasensitive dual-enhanced sandwich strategy for simultaneous detection of Escherichia coli and Staphylococcus aureus based on optimized aptamers-functionalized magnetic capture probes and graphene oxide-Au nanostars SERS tags.

In this work, a novel surface-enhanced Raman scattering (SERS) sandwich strategy biosensing platform has been established for simultaneously detecting Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Fe3O4@SiO2-Au nanocomposites (NCs) with varying amounts of Au nanocrystals were prepared, and the effect of interparticle gaps on SERS activity was studied by finite-difference time-domain (FDTD) method. The optimal magnetic SERS-active substrates (FS-A5) were functionalized with the specific aptamers to act as capture probes. Meanwhile, graphene oxide-Au nanostars (GO-Au NSs) decorated with Raman reporters and aptamers were used as SERS tags. The loading density of Au NSs on GO was tuned to change the number of SERS active sites. In this proposal, E. coli and S. aureus were first captured by capture probes and then bound with SERS tags to form a sandwich-like structure, which caused enhanced electromagnetic field because of the dual enhancement strategy. Under optimal conditions, SERS platform could detect E. coli and S. aureus simultaneously, and the detection limit was as low as 10 cfu/mL. Our sandwich assay-based dual-enhanced SERS platform provides a new idea for simultaneously detecting multiple pathogens with high selectivity and sensitivity, and thus will have more hopeful prospects in the field of food safety.

Multifunctional Plasmon-Tunable Au Nanostars and Their Applications in Highly Efficient Photothermal Inactivation and Ultra-Sensitive SERS Detection.

The development and application in different fields of multifunctional plasmonic nanoparticles (NPs) have always been research hotspots. Herein, multi-tip Au nanostars (NSs) with an anisotropic structure were fabricated for the photothermal therapy (PTT) of bacteria and surface-enhanced Raman scattering (SERS) detection of pollutants. The size and localized surface plasmon resonance (LSPR) characteristics of Au NSs were adjusted by varying Au seed additions. In addition, photothermal conversion performance of Au NSs with various Au seed additions was evaluated. Photothermal conversion efficiency of Au NSs with optimal Au seed additions (50 µL) was as high as 28.75% under 808 nm laser irradiation, and the heat generated was sufficient to kill Staphylococcus aureus (S. aureus). Importantly, Au NSs also exhibited excellent SERS activity for the 4-mercaptobenzoic acid (4-MBA) probe molecule, and the local electromagnetic field distribution of Au NSs was explored through finite-difference time-domain (FDTD) simulation. As verified by experiments, Au NSs' SERS substrate could achieve a highly sensitive detection of a low concentration of potentially toxic pollutants such as methylene blue (MB) and bilirubin (BR). This work demonstrates a promising multifunctional nanoplatform with great potential for efficient photothermal inactivation and ultra-sensitive SERS detection.

Magnetic-Core-Shell-Satellite Fe3O4-Au@Ag@(Au@Ag) Nanocomposites for Determination of Trace Bisphenol A Based on Surface-Enhanced Resonance Raman Scattering (SERRS).

As a typical representative of endocrine-disrupting chemicals (EDCs), bisphenol A (BPA) is a common persistent organic pollutant in the environment that can induce various diseases even at low concentrations. Herein, the magnetic Fe3O4-Au@Ag@(Au@Ag) nanocomposites (CSSN NCs) have been prepared by self-assembly method and applied for ultra-sensitive surface-enhanced resonance Raman scattering (SERRS) detection of BPA. A simple and rapid coupling reaction of Pauly's reagents and BPA not only solved the problem of poor affinity between BPA and noble metals, but also provided the SERRS activity of BPA azo products. The distribution of hot spots and the influence of incremental introduction of noble metals on the performance of SERRS were analyzed by a finite-difference time-domain (FDTD) algorithm. The abundance of hot spots generated by core-shell-satellite structure and outstanding SERRS performance of Au@Ag nanocrystals were responsible for excellent SERRS sensitivity of CSSN NCs in the results. The limit of detection (LOD) of CSSN NCs for BPA azo products was as low as 10-10 M. In addition, the saturation magnetization (Ms) value of CSSN NCs was 53.6 emu·g-1, which could be rapidly enriched and collected under the condition of external magnetic field. These magnetic core-shell-satellite NCs provide inspiration idea for the tailored design of ultra-sensitive SERRS substrates, and thus exhibit limitless application prospects in terms of pollutant detection, environmental monitoring, and food safety.

Multifunctional magnetic Fe3O4/Cu2O-Ag nanocomposites with high sensitivity for SERS detection and efficient visible light-driven photocatalytic degradation of polycyclic aromatic hydrocarbons (PAHs).

Polycyclic aromatic hydrocarbons (PAHs) with carcinogenic, teratogenic and mutagenic properties are persistent organic pollutants in the environment. Herein, the novel multifunctional Fe3O4/Cu2O-Ag nanocomposites (NCs) have been established for ultra-sensitive surface-enhanced Raman scattering (SERS) detection and visible light-driven photocatalytic degradation of PAHs. Fe3O4/Cu2O-Ag NCs with different amounts of Ag nanocrystals were synthesized, and the effect of Ag contents on SERS performance was studied by finite-difference time-domain (FDTD) algorithm. The synergistic interplay of electromagnetic and chemical enhancement was responsible for excellent SERS sensitivity of Fe3O4/Cu2O-Ag NCs. The limit of detection (LOD) of optimal SERS substrates (FCA-2 NCs) for Nap, BaP, Pyr and Ant was as low as 10-9, 10-9, 10-9 and 10-10 M, respectively. The SERS detection of PAHs in actual soil environment was also studied. Moreover, a simple SERS method was used to monitor the photocatalytic process of PAHs. The recovery and reuse of Fe3O4/Cu2O-Ag NCs were achieved through magnetic field, and the outstanding SERS and photocatalytic performance were still maintained even after eight cycles. This magnetic multifunctional NCs provide a unique idea for the integration of ultra-sensitive SERS detection and efficient photocatalytic degradation of PAHs, and thus will have more hopeful prospects in the field of environmental protection.

Effect of thermal treatment of Pd decorated Fe/C nanocatalysts on their catalytic performance for formic acid oxidation.

The thermal treatment of bimetallic nanocatalysts plays an important role in determining their catalytic performance. Here tuning the surface oxidized metal species of bimetallic Pd-Fe electrocatalysts for the formic acid (FA) oxidation reaction is reported and a correlation between the surface oxidized metal species of the Pd-Fe nanoparticles and their catalytic activities is proposed. The structural details of the Pd-Fe/C catalysts are characterized by X-ray diffraction, X-ray photoelectron spectroscopy and high-sensitivity low-energy ion scattering (HS-LEIS). Cyclic voltammetry measurements demonstrated that the mass activity of the Pd-Fe nanoparticles with a molar ratio of Pd/Fe = 1/15 is about 7.4 times higher than that of Pd/C. This enhancement could be attributed to the synergistic effect between Pd(0) and Pd oxidized species on the surface of the Pd-Fe/C treated sample and electronic effects. This finding demonstrates the importance of surface oxidized metal species at the nanoscale in harnessing the true electrocatalytic potential of bimetallic nanoparticles and opens up strategies for the development of highly active bimetallic nanoparticles for electrochemical energy conversion.

[Influencing factors for lymphocyte subsets in children aged 0-6 years].

OBJECTIVE: To investigate the influencing factors for lymphocyte subsets in children 0 to 6 years of age. METHODS: Umbilical artery blood samples from 45 healthy full-term infants and venous blood samples from 79 healthy children between 0 and 6 years were collected. According to the methods of delivery, the full-term infants were divided into vaginal delivery group (n=22) and cesarean section group (n=23). Healthy children were divided into different age groups: 28 days to 12 months (n=25), 1-3 years (n=26), and 3-6 years (n=28). Lymphocyte subsets were examined by flow cytometry. The influencing factors including delivery method, sex, and age, which might have an effect on the lymphocyte subsets, were analyzed. RESULTS: There were significant differences in T and Ts cell counts, percentage of B cells, and percentage and count of natural killer (NK) cells between the full-term infants of vaginal delivery and cesarean section (P<0.05). The absolute counts and percentages of different lymphocyte subsets showed no significant differences between males and females in healthy children (P>0.05). The counts of all lymphocyte subsets except Ts and NK cells varied significantly between different age groups (P<0.05). CONCLUSIONS: Lymphocyte subsets in children under 6 years of age are more profoundly affected by age. Delivery method is also a contributing factor in newborn infants. The reference range of lymphocyte subsets in children should be established for different age groups.

Effect of soybean hull supplementation to finishing pigs on the emission of noxious gases from slurry.

Ninety six pigs were assigned on the basis of body weight (BW) to one of four dietary treatments (4 pigs per pen and 6 pens per treatment) and fed for 4 weeks. Four 14.85% CP diets were formulated to contain graded levels of soybean hulls at 0, 5, 10, or 15%, respectively. The results showed that treatments did not affect growth performance. Coefficient of total tract apparent digestibility (CTTAD) for dry matter (DM) and blood urea nitrogen (BUN) concentrations were decreased linearly (P < 0.05) with the addition level of soybean hulls. Slurry ammonia nitrogen (NH(3)-N) was not affected with the increased soybean hulls levels, but volatile fatty acids (VFA) were linearly (P < 0.05) increased. Slurry pH and ammonia (NH(3)) emissions were significantly decreased by the addition of soybean hulls (Linear, P < 0.05). Conversely, slurry hydrogen sulphide (H(2)S) emissions exhibited an increase with the addition of soybean hulls (Linear, P < 0.10). Our data indicate that soybean hulls inclusion can decrease slurry pH value and NH(3) emission without any negative influence on growth performance.