Carrier Surface Research Articles

Spin selection in atomic-level chiral metal oxide for photocatalysis

The spin degree of freedom is an important and intrinsic parameter in boosting carrier dynamics and surface reaction kinetics of photocatalysis. Here we show that chiral structure in ZnO can induce spin selectivity effect to promote photocatalytic performance. The ZnO crystals synthesized using chiral methionine molecules as symmetry-breaking agents show hierarchical chirality. Magnetic circular dichroism spectroscopic and magnetic conductive-probe atomic force microscopic measurements demonstrate that chiral structure acts as spin filters and induces spin polarization in photoinduced carriers. The polarized carriers not only possess the prolonged carrier lifetime, but also increase the triplet species instead of singlet byproducts during reaction. Accordingly, the left- and right-hand chiral ZnO exhibit 2.0- and 1.9-times higher activity in photocatalytic O2 production and 2.5- and 2.0-times higher activities in contaminant photodegradation, respectively, compared with achiral ZnO. This work provides a feasible strategy to manipulate the spin properties in metal oxides for electron spin-related redox catalysis.

Synthesis and Characterization of Cadmium Ion-Imprinted/Natural Sand Composite and Research on Its Adsorption Properties

Cadmium is a common heavy metal that can cause serious harm to human health, even in trace amounts. Therefore, it is of great significance to develop environmentally friendly, inexpensive, and readily available adsorbent materials with high selectivity. By preparing ion-imprinted composites on the surface of a suitable carrier through surface imprinting, the number of effective adsorption sites can be increased, and target ions can be more quickly identified. In this study, we synthesized a cadmium ion-imprinted/natural sand composite material (NS/Cd-IIP) using natural sand as the carrier, Cd(II) as the template ion, and acrylamide as the functional monomer. A series of characterization techniques were employed to confirm the composite. Static and dynamic adsorption experiments were conducted to investigate various factors affecting its adsorption performance. The optimum adsorption pH was found to be 7, and the adsorption equilibrium time was determined to be 105 min. The imprinted composites exhibited a static adsorption saturation capacity of 33.84 mg·g−1, which was significantly higher than that of the non-imprinted composites. The adsorption behavior of composites followed Langmuir isotherm and quasi-second-order kinetic. Thermodynamic parameters indicated that the adsorption process of NS/Cd-IIP for Cd(II) was exothermic, entropic, and spontaneous. The selectivity of NS/Cd-IIP towards Cd(II) was significantly higher than that towards other ions. By optimizing the dynamic adsorption conditions, the maximum adsorption capacity of NS/Cd-IIP was determined to be 3.77 mg·g−1, and the adsorption behavior conformed to the Thomas model. NS/Cd-IIP was used as a solid-phase extractant for trace determination of Cd(II) in tap water, achieving a recovery rate exceeding 101%.

Mechanism of high PEC performance of B-doped TiO2 nanotube arrays: Highly reactive surface defects and lattice stress

The role of the boron (B) doping induced defect state in the PEC process is still unclear though B doped TiO2 nanotube arrays (TNAs) via anodic oxidation has commonly used to improve the photocatalytic decomposition of water by TNAs. Therefore, this work aims to establish the underlying reasons for the high PEC reactivity and stability maintained by the B doping induced defective states. Special attention is paid to the differences in carrier behavior and surface reactivity in the PEC process between the B doped induced and NaBH4 treatment induced defective states. DFT calculations show that B doping can effectively reduce the generation energy of Ti3+/Vo (oxygen vacancies) pairs and enhance the adsorption energy of defects on the surface of TiO2 (101) for H2O and ·OH. Moreover, due to the presence of B atoms, the surface defects of TiO2 can maintain high adsorption of H2O and ·OH, without being deactivated by the healing of oxygen vacancies, which ensures the stability and activity of the catalyst. Meanwhile, the lattice stress induced by B doping forms the internal electric field, which ensures the efficient separation of carriers in the bulk phase and avoids the negative effect of bulk phase defects on carrier separation.

Humoral Response to the Acetalated Dextran M2e Vaccine is Enhanced by Antigen Surface Conjugation.

The influenza A virus causes substantial morbidity and mortality worldwide every year and poses a constant threat of an emergent pandemic. Seasonal influenza vaccination strategies fail to provide complete protection against infection due to antigenic drift and shift. A universal vaccine targeting a conserved influenza epitope could substantially improve current vaccination strategies. The ectodomain of the matrix 2 protein (M2e) of influenza is a highly conserved epitope between virus strains but is also poorly immunogenic. Administration of M2e and the immunostimulatory stimulator of interferon genes (STING) agonist 3'3'-cyclic guanosine-adenosine monophosphate (cGAMP) encapsulated in microparticles made of acetalated dextran (Ace-DEX) has previously been shown to be effective for increasing the immunogenicity of M2e, primarily through T-cell-mediated responses. Here, the immunogenicity of Ace-DEX MPs delivering M2e was further improved by conjugating the M2e peptide to the particle surface in an effort to affect B-cell responses more directly. Conjugated or encapsulated M2e co-administered with Ace-DEX MPs containing cGAMP were used to vaccinate mice, and it was shown that two or three vaccinations could fully protect against a lethal influenza challenge, while only the surface-conjugated antigen constructs could provide some protection against lethal challenge with only one vaccination. Additionally, the use of a reducible linker augmented the T-cell response to the antigen. These results show the utility of conjugating M2e to the surface of a particle carrier to increase its immunogenicity for use as the antigen in a universal influenza vaccine.

Synergistic mechanism of B doping and NiO loading on the excellent PEC performance and high stability of TiO2 nanotube photoanodes

The severe photogenerated charge recombination rate, poor visible light utilization and slow oxygen precipitation kinetics are the technical bottlenecks limiting the photo-electrolysis of TiO2 nanotube array (TNAs) photoanode for hydrogen production from water. To solve these problems, NiO nanoparticles were uniformly loaded into B-doped TNAs by the CV method. It is found that B-doping improves the energy band structure of TNAs, and doping-induced surface defects could become traps for photogenerated carriers to substantially improve the charge separation efficiency of the bulk phase. The P-N junctions formed between TiO2 anatase and NiO nanoparticles not only promoted the OER kinetics at the interface but also greatly improved the surface carrier separation efficiency of the catalyst, as well as ensured the stability and activity of the B-doping-induced surface defects. Moreover, the carrier concentration and visible light absorption properties of TNAs were enhanced and improved. Due to the synergistic effect of B doping and NiO loading, the bulk charge separation efficiency and surface charge separation efficiency of NiO/BT (B doping and NiO loading TNAs) were as high as 88.9 and 82.4%, respectively, at 1.23 V vs. RHE, and the photocurrent density reached 2.05 mA/cm2, which was 10 times higher than that of pure TNAs.

Vaccination against Epstein-Barr Latent Membrane Protein 1 Protects against an Epstein-Barr Virus-Associated B Cell Model of Lymphoma.

In this study, we demonstrate that expression of viral latent membrane protein 1 (LMP1) in a mouse B cell line renders the animals responsive to protection from a 38C13-LMP1 tumor challenge with a novel vaccine. The Epstein-Barr virus (EBV) preferentially infects circulating B lymphocytes, has oncogenic potential, and is associated with a wide variety of B cell lymphomas. EBV is ectotrophic to human cells, and currently there are no B cell animal models of EBV-associated lymphoma that can be used to investigate vaccine immunotherapy. Since most EBV-infected human tumor cells express latent membrane protein 1 (LMP1) on their surface, this viral antigen was tested as a potential target for an anticancer vaccine in a mouse model. Here, we describe a new mouse model of LMP1-expressing B cell lymphoma produced with plasmid transduction of 38C13 into mouse B cells. The expression of LMP-1 was confirmed with a western blot analysis and immunocytochemistry. We then designed a novel LMP1 vaccine, by fusing viral antigen LMP1 surface loop epitopes to the surface of a viral antigen carrier, the Tobacco Mosaic virus (TMV). Vaccinated mice produced high titer antibodies against the TMV-LMP1 vaccine; however, cellular responses were at the baseline, as measured with IFNγ ELISpot. Despite this, the vaccine showed significant protection from a 38C13-LMP1 tumor challenge. To provide additional immune targets, we compared TMV-LMP1 peptide immunization with DNA immunization with the full-length LMP1 gene. Anti-LMP1 antibodies were significantly higher in TMV-LMP1-vaccinated mice compared to the DNA-immunized mice, but, as predicted, DNA-vaccinated mice had improved cellular responses using IFNγ ELISpot. Surprisingly, the TMV-LMP1 vaccine provided protection from a 38C13-LMP1 tumor challenge, while the DNA vaccine did not. Thus, we demonstrated that LMP1 expression in a mouse B cell line is responsive to antibody immunotherapy that may be applied to EBV-associated disease.

Efficient Photoelectrochemical Hydrogen Generation Using Eco-Friendly "Giant" InP/ZnSe Core/Shell Quantum Dots.

InP quantum dots (QDs) are promising building blocks for use in solar technologies because of their low intrinsic toxicity, narrow bandgap, large absorption coefficient, and low-cost solution synthesis. However, the high surface trap density of InP QDs reduces their energy conversion efficiency and degrades their long-term stability. Encapsulating InP QDs into a wider bandgap shell is desirable to eliminate surface traps and improve optoelectronic properties. Here, we report the synthesis of "giant" InP/ZnSe core/shell QDs with tunable ZnSe shell thickness to investigate the effect of the shell thickness on the optoelectronic properties and the photoelectrochemical (PEC) performance for hydrogen generation. The optical results demonstrate that ZnSe shell growth (0.9-2.8 nm) facilitates the delocalization of electrons and holes into the shell region. The ZnSe shell simultaneously acts as a passivation layer to protect the surface of InP QDs and as a spatial tunneling barrier to extract photoexcited electrons and holes. Thus, engineering the ZnSe shell thickness is crucial for the photoexcited electrons and hole transfer dynamics to tune the optoelectronic properties of "giant" InP/ZnSe core/shell QDs. We obtained an outstanding photocurrent density of 6.2 mA cm-1 for an optimal ZnSe shell thickness of 1.6 nm, which is 288% higher than the values achieved from bare InP QD-based PEC cells. Understanding the effect of shell thickness on surface passivation and carrier dynamics offers fundamental insights into the suitable design and realization of eco-friendly InP-based "giant" core/shell QDs toward improving device performance.

Substituent Effect to Fine-Tune Energy Levels of Atom-Precise [MoOS3]2- Modified Cu(I) Thiolate Clusters Boosting Recyclable Photocatalysis.

The propulsion of photocatalytic hydrogen (H2) production is limited by the rational design and regulation of catalysts with precise structures and excellent activities. In this work, the [MoOS3]2- unit is introduced into the Cu(I) clusters to form a series of atomically-precise Mo(VI)-Cu(I) bimetallic clusters of [Cu6(MoOS3)2(C6H5(CH2)S)2(P(C6H4-R)3)4]·xCH3CN (R = H, CH3, or F), which show high photocatalytic H2 evolution activities and excellent stability. By electron push-pull effects of the surface ligand, highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels of these Mo(VI)-Cu(I) clusters can be finely tuned, promoting the resultant visible-light-driven H2 evolution performance. Furthermore, Mo(VI)-Cu(I) clusters loaded onto the surface of magnetic Fe3O4 carriers significantly reduced the loss of catalysts in the collection process, efficiently addressing the recycling issues of such small cluster-based catalyst. This work not only highlights a competitively universal approach on the design of high-efficiency cluster photocatalysts for energy conversion, but also makes it feasible to manipulate the catalytic performance of clusters through a rational substituent strategy.

Substituent Effect to Fine‐Tune Energy Levels of Atom‐Precise [MoOS3]2− Modified Copper(I) Thiolate Clusters Boosting Recyclable Photocatalysis

AbstractThe propulsion of photocatalytic hydrogen (H2) production is limited by the rational design and regulation of catalysts with precise structures and excellent activities. In this work, the [MoOS3]2− unit is introduced into the CuI clusters to form a series of atomically‐precise MoVI−CuI bimetallic clusters of [Cu6(MoOS3)2(C6H5(CH2)S)2(P(C6H4−R)3)4] ⋅ xCH3CN (R=H, CH3, or F), which show high photocatalytic H2 evolution activities and excellent stability. By electron push‐pull effects of the surface ligand, highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels of these MoVI−CuI clusters can be finely tuned, promoting the resultant visible‐light‐driven H2 evolution performance. Furthermore, MoVI−CuI clusters loaded onto the surface of magnetic Fe3O4 carriers significantly reduced the loss of catalysts in the collection process, efficiently addressing the recycling issues of such small cluster‐based catalyst. This work not only highlights a competitively universal approach on the design of high‐efficiency cluster photocatalysts for energy conversion, but also makes it feasible to manipulate the catalytic performance of clusters through a rational substituent strategy.

Synthesis of new water treatment photocatalytic coatings with controllable functional properties based on the SrO-Bi2O3-SiO2 system that use the energy of solar radiation

This work is devoted to the study of water purification from organic pollutants using new environmentally safe photocatalysts capable of using solar insolation to oxidize organic pollutants. Most methods of creating photocatalysts allow obtaining them only in powder form, which limits their application in water treatment plants. In this regard, photocatalysts formed as coatings on the carrier surface may be more promising. This work contributes to solving the problem of developing a technologically concise and economical method of creating bismuth photocatalytic coatings with biological indifference and high light absorption efficiency (LAE) of solar irradiation. The developed cleaning material is a structurally organized system consisting of a ceramic carrier on which a photocatalytic coating is formed. The coating was formed by soaking the silicate carrier in a bismuth precursor solution (BPS) followed by drying and oxidative pyrolysis. The highest catalytic activity and LAE (58.3–60.3%) were observed for the materials obtained at 10–15% wt. bismuth in BPS. The highest hydrolytic stability was observed at 25% wt. bismuth in BPS. Strontium bismuthate SrBi7.65O13 was the dominant phase in the coating composition for the samples with the highest activity and LAE. Increasing the content of another photocatalytically active phase Bi4Si3O12 resulted in the LAE decreasing to 51.9%, providing greater hydrolytic stability of the material. The proposed method allows for flexibly controlling the properties of the obtained photocatalytic coatings, thus making possible to directionally create different types of materials to be applied in the field of wastewater treatment.

Process optimization of a moving bed bioreactor undergoing simultaneous nitrification and denitrification for wastewater in the absence of organic carbon

ABSTRACT Moving bed bioreactors are efficient for the removal of nitrogen effluents by simultaneous nitrification and denitrification (SND), which is particularly challenging for effluents with low C/N ratio due to insufficient carbon available for denitrification. The addition of external organic carbon in such cases increases treatment costs. Endogenous degradation of biomass offers a cost-effective and persistent source of carbon. Internal carbon leads to low denitrification rates and optimizing the biomass content leads to a sustainable solution for treating such effluents. The present study aims to optimize the process of SND using endogenous carbon by investigating the effect of operational parameters like dissolved oxygen, influent ammonium (NH4–N) loading, hydraulic retention time (HRT) and carrier filling ratio (CFR). The synthetic wastewater used in the study does not inherently contain any organic carbon, thus indicating the responsible carbon for denitrification to be of internal origin. Using a novel carrier for multispecies biofilm development, initial NH4–N concentration variation showed an insignificant effect on SND efficiency. At higher loading, nitrite accumulation due to incomplete denitrification was observed. The effect of CFR was investigated in a range of 20–35%, beyond which non-homogeneous mixing was caused in the reactor. Under controlled DO and temperature of about 5 mg/L and 28 ± 2°C, respectively, an optimum filling ratio of 35% was finalised, resulting in an SND efficiency of 97.9% at 22 h HRT for high influent NH4–N concentration of 500 mg/L. Bacteriological species identification revealed the coexistence of nitrogen-fixing, aerobic nitrifying and anaerobic denitrifying bacteria in the biofilm growing on the biocarrier. Mechanism of SND occurring in aerobic moving bed bioreactors: Laboratory-scale aerobic Moving Bed Bioreactor setup for a continuous study evaluating the influence of operational parameters on SND Occurrence of aerobic and anoxic zones in biofilm grown on the surface of novel carriers due to diffusional gradient of dissolved oxygen

Biogas conversion to liquid fuels via chemical looping single reactor system with CO2 utilization

The chemical looping single reactor (CLSR) system utilizing calcium ferrite as oxygen carriers represents an innovative approach to biogas reforming, which has the potential to enhance the efficiency and sustainability of biogas production. In this process, an oxy-combustion burner supplies the necessary endothermic heat while CO2 is simultaneously utilized, resulting in an autothermal process that generates high-purity syngas. Nearly 20% higher CO2 utilization can be achieved compared to the tri-reforming, owing to the higher driving force for CO2 oxidation in the counter-current moving bed and steam knock-out before inletting the flue gas into the reactor bottom. Additionally, the CLSR system is robust to variations in biogas to oxygen carrier ratios and CO2 concentration of the inlet feedstock, maintaining the outlet syngas purity within 1% variation. The effects of temperature, pressure, heat integration, and additional H2O/CO2 flow rate on the system performance are discussed, and the optimized scenarios are used for liquid fuel generation. The proposed process achieves about 13% reduction in syngas requirement compared to the conventional tri-reforming for the same amount of liquid fuel production. The feasibility of the CLSR system is further experimentally verified under various conditions. The results reveal the occurrence of CO2 counter-oxidation reactions on the surface of calcium ferrite oxygen carriers and demonstrate that higher temperatures are beneficial for the CH4 reforming reaction.

Quantum Shell in a Shell: Engineering Colloidal Nanocrystals for a High-Intensity Excitation Regime.

Many optoelectronic processes in colloidal semiconductor nanocrystals (NCs) suffer an efficiency decline under high-intensity excitation. This issue is caused by Auger recombination of multiple excitons, which converts the NC energy into excess heat, reducing the efficiency and life span of NC-based devices, including photodetectors, X-ray scintillators, lasers, and high-brightness light-emitting diodes (LEDs). Recently, semiconductor quantum shells (QSs) have emerged as a promising NC geometry for the suppression of Auger decay; however, their optoelectronic performance has been hindered by surface-related carrier losses. Here, we address this issue by introducing quantum shells with a CdS-CdSe-CdS-ZnS core-shell-shell-shell multilayer structure. The ZnS barrier inhibits the surface carrier decay, which increases the photoluminescence (PL) quantum yield (QY) to 90% while retaining a high biexciton emission QY of 79%. The improved QS morphology allows demonstrating one of the longest Auger lifetimes reported for colloidal NCs to date. The reduction of nonradiative losses in QSs also leads to suppressed blinking in single nanoparticles and low-threshold amplified spontaneous emission. We expect that ZnS-encapsulated quantum shells will benefit many applications exploiting high-power optical or electrical excitation regimes.

Effect of different synthesis methodologies on the adsorption of iodine

Radioactive nuclides such as cesium, ruthenium, and iodine are difficult to remove in radioactive wastewater, which could be removed by coprecipitation of special chemical precipitants. In this study, dynamic Cu/Ag-mordenite (Cu/Ag-MOR) material was synthesized to be treated as the precipitant to selectively adsorb the iodine ion (I−) through controlled chemisorption combined with physical adsorption. XRD, XPS, and FTIR characterization demonstrated the successful modification of the MOR carrier surface by Cu/Ag particles and the high selectivity of the active component Cu (I) on the dynamic Cu/Ag-MOR material. SEM, TEM, and BET methods were used to characterize the Cu/Ag-MOR material, demonstrating these results: the MOR carried a stable porous structure, which allowed the silver to be well dispersed on its surface. The silver improved the copper distribution by being well-coated by the copper species. Furthermore, the analysis of the factors influencing the chemical plating of copper showed that the pH, the concentration of EDTA-2Na and the temperature all influenced the deposition rate of Cu2O. The activation energy for Cu2O deposition in dynamic Cu/Ag-MOR was 20.31 kJ/mol. The highest removal of I− in the presence of dynamic Cu/Ag-MOR could reach 99.1% in the adsorption tests. The adsorption kinetics was under a proposed second-order model, with chemisorption being the controlling step of the reaction. The adsorption/desorption experiments demonstrated the reusability of the nano-sorbent. It was also demonstrated that dynamic Cu/Ag-MOR materials showed good applicability in complex situations where multiple pollutants co-exist.

Design and Analysis of Fixed-Segment Carrier at Carbon Thrust Bearing

Abstract: This thesis work aimed to provide a design and analysis of fixed segment carrier at carbon thrust bearing. With increased the bearing efficiency and reduced the frictional loss and wear resistance. Thrust bearings plays vital role in submersible pumps. Thrust bearings are fixed bottom of the submersible pumps so total thrust or axial load acting on the thrust collar. Thrust collar are manufacturing with resin mixed carbon and casting material and the segments are manufacturing with casting material and stainless steel material. Two types of materials combines to manufacture the segment carrier. The materials hardness and density properties are different from on materials to another material. If suddenly power cut is happen the total load acting on thrust collar. The collar under heavy load carbon surface and segment carrier surface are scratched or damaged the carbon surface. This type of damages are affecting submersible pump. Submersible pumps are fixed with maximum 900 feet under the boar well but this damages are happen we spend more money to lifting the pump from well and also time is wasted. Segment carrier segment surface and thrust pad surface in between micron level film thickness. If the loose segment carrier the loose segment will tilt under the load and vibration of pump. The thrust collar surface is scratched with thrust collar is not rotate because the thrust collar is fitted with rotating shaft with key way. In this study the segment carrier were made with same materials and the hardness of the materials is same and making process are compared to normal bearing were reduced. The segment carrier is made with stainless steel 410 material. The materials are bought a rod or using pattern with investment casting. After the materials is after completing machining process will goes to hardening and materials surface will go to grinding process. The segment surfaces are grinded and achieve the required surface finish. The surface finish techniques are available no of methods. Triondur coating system is more effective than other process. The grinded segment carrier surfaces are goes to next process of lapping. Here the surface is lapped and get required level of surface roughness. In this process the surface roughness is get required level. Because the lapping coating ratio is high the material removal and surface roughness is get more level like 0.2 micron. The diamond powder coating using 100 CRT is lapping process to achieve the required surface finish. The main purpose of the study is to reduce the bearing damages and frictional loss and wear loss and pump damages. And increase the pump life and reduce the raw materials usage

TRPIV experimental study of coherent structures and their burst events in the boundary layer on JBC

Turbulent drag on the hull surface is one of the main sources of drag during the navigation of a ship, which is significantly influenced by the boundary layer's coherent structures. To investigate the evolution and energy transport of the coherent structures, this study applied time-resolved particle image velocimetry (TRPIV) to realise the fine measurement of the flow field at different upstream and downstream positions on the surface of the Japanese bulk carrier (JBC). Finite-time Lyapunov exponent (FTLE), proper orthogonal decomposition (POD) and quadrant analysis were used to conduct a detailed analysis of the coherent structures and their evolution. The results show that the skin friction drag is notably affected by the coherent structures at the turbulent boundary layer of the JBC hull surface and their burst events. In addition, the turbulent energy that enhances the skin friction drag mainly comes from the outward-inward transport in the turbulent boundary layer, and the intensity of fluctuation velocity contained within the burst events also obviously affects the skin friction drag. The results of this study can provide physical evidence for the optimisation design of similar hull configurations, the optimisation design of unmanned underwater vehicle configuration, and the planning of drag reduction strategy.

Correlating the Dipolar Interactions Induced Magneto-Viscoelasticity and Thermal Conductivity Enhancements in Nanomagnetic Fluids.

The effective thermal management of electronic system holds the key to maximize their performance. The recent miniaturization trends require a cooling system with high heat flux capacity, localized cooling, and active control. Nanomagnetic fluids (NMFs) based cooling systems have the ability to meet the current demand of the cooling system for the miniaturized electronic system. However, the thermal characteristics of NMFs have a long way to go before the internal mechanisms are well understood. This review mainly focuses on the three aspects to establish a correlation between the thermal and rheological properties of the NMFs. First, the background, stability, and factors affecting the properties of the NMFs are discussed. Second, the ferrohydrodynamic equations are introduced for the NMFs to explain the rheological behavior and relaxation mechanism. Finally, different theoretical and experimental models are summarized that explain the thermal characteristics of the NMFs. Thermal characteristics of the NMFs are significantly affected by the morphology and composition of the magnetic nanoparticles (MNPs) in NMFs as well as the type of carrier liquids and surface functionalization that also influences the rheological properties. Thus, understanding the correlation between the thermal characteristics of the NMFs and rheological properties helps develop cooling systems with improved performance.

Bandgap engineered, quantum-confined ultrathin Te layer for highly effective back surface field in Si/organic hybrid solar cells

The suppression of back surface carrier recombination is primary importance for efficient Si-based solar cells. It is usually achieved with back surface field (BSF) by introducing a highly doped layer on the rear surface, which require a high temperature doping processes and involves toxic gasses. Here, we report that a high power conversion efficiency of 13.1% with device area of 1cm2 has been achieved for planar Si-PEDOT:PSS hybrid solar cells by depositing a ultrathin tellurium (Te) layer between silicon and rear contact, without any high temperature process or further treatment. Current-voltage, electrochemical impedance spectroscopy, quasi-steady-state-photoconductance measurements are used to investigate the effect of Te BSF layer on the device performance. The insertion of Te BSF layer have successfully reduced charge carrier recombination at rear interface. In addition, it could reduce the contact resistance thanks to the favorable band alignment originated from quantum confinement effect, resulting in improved current density and fill factor. This is the very first demonstration that a quantum-confined material can be used as an effective passivating back surface field layer in Si-organic hybrid solar cells.

DPA-Zinc around Polyplexes Acts Like PEG to Reduce Protein Binding While Targeting Cancer Cells.

Gene therapy holds great promise as an effective treatment for many diseases of genetic origin. Gene therapy works by employing cationic polymers, liposomes, and nanoparticles to condense DNA into polyplexes via electronic interactions. Then, a therapeutic gene is introduced into target cells, thereby restoring or changing cellular function. However, gene transfection efficiency remains low in vivo due to high protein binding, poor targeting ability, and substantial endosomal entrapment. Artificial sheaths containing PEG, anions, or zwitterions can be introduced onto the surface of gene carriers to prevent interaction with proteins; however, they reduce the cellular uptake efficacy, endosomal escape, targeting ability, thereby, lowering gene transfection. Here, it is reported that linking dipicolylamine-zinc (DPA-Zn) ions onto polyplex nanoparticles can produce a strong hydration water layer around the polyplex, mimicking the function of PEGylation to reduce protein binding while targeting cancer cells, augmenting cellular uptake and endosomal escape. The polyplexes with a strong hydration water layer on the surface can achieve a high gene transfection even in a 50% serum environment. This strategy provides a new solution for preventing protein adsorption while improving cellular uptake and endosomal escape.

Preparation of Micron-Sized TS-1 Spherical Membrane Catalysts and Their Performance in the Epoxidation of Chloropropene.

Titanium silica (TS-1) membrane catalysts grown on the surfaces of spherical substrates can both exploit the high catalytic performance and facilitate their separation from products after the reaction. In this work, a simple static crystallization method was used to perform the in situ construction of a TS-1 membrane on the surfaces of micron-sized spherical carriers. The shortcomings of the TS-1 membrane under static crystallization conditions were overcome by in situ dynamic crystallization, and the effect of rotation speed on the formation of the molecular sieve membrane was investigated. The results showed that the molecular sieve membrane was smooth and homogeneous, with a higher synthesis efficiency at a slow rotational speed. The micron TS-1 spherical membrane catalytic chloropropene epoxidation reaction was investigated in a fixed bed, and the conversion of hydrogen peroxide and selectivity of epichlorohydrin reached 99.4 and 96.8%, respectively. After being reused twice, the catalyst still maintained a stable catalytic performance.