Substitution Sites Research Articles

Site-specific atomic substitution in a giant magnetocaloric Fe2P -type system

Giant magnetocaloric (GMC) materials constitute a requirement for near room temperature magnetic refrigeration. (Fe,Mn)$_2$(P,Si) is a GMC compound with strong magnetoelastic coupling. The main hindrance towards application of this material is a comparably large temperature hysteresis, which can be reduced by metal site substitution with a nonmagnetic element. However, the (Fe,Mn)$_2$(P,Si) compound has two equally populated metal sites, the tetrahedrally coordinated $3f$ and the pyramidally coordinated $3g$ sites. The magnetic and magnetocaloric properties of such compounds are highly sensitive to the site specific occupancy of the magnetic atoms. Here we have attempted to study separately the effect of $3f$ and $3g$ site substitution with equal amounts of vanadium. Using formation energy calculations, the site preference of vanadium and its influence on the magnetic phase formation are described. A large difference in the isothermal entropy change (as high as 44\%) with substitution in the $3f$ and $3g$ sites is observed. The role of the lattice parameter change with temperature and the strength of the magnetoelastic coupling on the magnetic properties are highlighted.

Geographical origin of Plasmodium vivax in the Hainan Island, China: insights from mitochondrial genome

BackgroundHainan Province, China, has been an endemic region with high transmission of Plasmodium falciparum and Plasmodium vivax. Indigenous malaria caused by P. vivax was eliminated in Hainan in 2011, while imported vivax malaria remains. However, the geographical origin of P. vivax cases in Hainan remains unclear.MethodsIndigenous and imported P. vivax isolates (n = 45) were collected from Hainan Province, and the 6 kb mitochondrial genome was obtained. Nucleotide (π) and haplotype (h) diversity were estimated using DnaSP. The numbers of synonymous nucleotide substitutions per synonymous site (dS) and nonsynonymous nucleotide substitutions per nonsynonymous site (dN) were calculated using the SNAP program. Arlequin software was used to estimate the genetic diversity index and assess population differentiation. Bayesian phylogenetic analysis of P. vivax was performed using MrBayes. A haplotype network was generated using the NETWORK program.ResultsIn total, 983 complete mitochondrial genome sequences were collected, including 45 from this study and 938 publicly available from the NCBI. Thirty-three SNPs were identified, and 18 haplotypes were defined. The haplotype (0.834) and nucleotide (0.00061) diversity in the Hainan populations were higher than China’s Anhui and Guizhou population, and the majority of pairwise FST values in Hainan exceeded 0.25, suggesting strong differentiation among most populations except in Southeast Asia. Most Hainan haplotypes were connected to South/East Asian and China’s others haplotypes, but less connected with populations from China's Anhui and Guizhou provinces. Mitochondrial lineages of Hainan P. vivax belonged to clade 1 of four well-supported clades in a phylogenetic tree, most haplotypes of indigenous cases formed a subclade of clade 1, and the origin of seven imported cases (50%) could be inferred from the phylogenetic tree, but five imported cases (42.8%) could not be traced using the phylogenetic tree alone, necessitating epidemiological investigation.ConclusionsIndigenous cases in Hainan display high genetic (haplotype and nucleotide) diversity. Haplotype network analysis also revealed most haplotypes in Hainan were connected to the Southeast Asian populations and divergence to a cluster of China’s other populations. According to the mtDNA phylogenetic tree, some haplotypes were shared between geographic populations, and some haplotypes have formed lineages. Multiple tests are needed to further explore the origin and expansion of P. vivax populations.

Multiple-site Ag doping in Bi[formula omitted]Se[formula omitted]: Compositional crossover from substitution to intercalation as revealed by photoelectron diffraction and X-ray fluorescence holography

The local structure around Ag atoms in Ag-doped Bi2Se3 (AgxBi2−ySe3) was investigated by photoelectron diffraction and X-ray fluorescence holography to understand the manner of Ag atom doping. At a low Ag concentration (x=0.05), photoelectron diffraction indicated that Ag atoms occupied Bi substitution sites. However, a mere accumulation of holes via Ag substitution for Bi fails to explain the observed variation previously reported in the transport properties of Ag-doped Bi2Se3 with different x values. In particular, simple Ag substitution for Bi fails to explain the pinning of the Fermi level at the bottom of conduction band, as suggested by the observed transport properties. In the case of a high Ag concentration (x=0.2), photoelectron diffraction suggested that the Ag atoms occupied not only the substitutional Bi site but also multiple interstitial sites, namely, the octahedral site in the van der Waals interlayer and the interstitial site in the Se layer. Ag 3d photoelectron spectra revealed that the Ag atoms had the same oxidation state, +1, regardless of the type of occupied site. Furthermore, X-ray fluorescence holography was employed for a model-free local structural analysis that refined the exact locations of Ag atoms in the Bi2Se3 crystal lattice. The behavioral crossover documented herein from hole doping at the substitutional site to electron doping at multiple sites reasonably explains the dependence of electronic structures and transport properties of Ag-doped Bi2Se3 on dopant concentration.

Effect of propionyl group on birefringence and wavelength dispersion of propionylated cellulose acetate optical compensation films

Propionylated cellulose acetate (PCA) with different propionyl substitution degrees (DSPr) was synthesized, and the corresponding optical films were prepared by solution casting. The birefringence and its wavelength dispersion of PCA films stretched at 10 °C above and below the glass transition temperature (Tg) with different draw ratios (DR) were studied. The introduction of propionyl group at different substitution sites present different contribution to birefringence and its wavelength dispersion. The propionyl group at C-2 and C-3 sites have a larger positive orientation birefringence with stronger normal wavelength dispersion, while that at the C-6 site shows a smaller negative orientation birefringence with weaker normal wavelength dispersion compared with the acetyl group. Compared with CA film, the introduction of the propionyl group weakens the orientation birefringence of PCA film. With the increase of DSPr from 0.023 to 0.303, the occurrence of propionyl substitution only at the C-6 site turns to C-2, C-3 and C-6 sites and the wavelength dispersion of in-plane birefringence (Δnin) decreases. When DSPr is further increased to 0.537, the Δnin and out-of-plane birefringence (Δnth) of PCA films at different DR show a very weak wavelength dispersion with the relative horizontal curves. Current results indicate that when the substitution degree of the propionyl group and acetyl group is suitable, the wavelength dispersion of PCA film can be eliminated.

Theoretical analysis of crystal field parameters and zero field splitting parameters for Mn2+ ions in tetramethylammonium tetrachlorozincate (TMATC-Zn)

Superposition model (SPM) analysis is employed for modeling the crystal field parameters (CFPs) as well as the zero field splitting (ZFS) parameters (ZFSPs) for Mn2+ ions doped into tetramethylammonium tetrachlorozincate, [N(CH3)4]2ZnCl4 crystal (denoted TMATC-Zn). SPM analysis utilizes structural data to predict CFPs and ZFSPs determined for the dopant ions by optical and EMR spectroscopy, respectively. We report model calculations aimed at investigating the two structural options for dopant Mn2+ ions in TMATC-Zn: substitutional and interstitial sites. SPM is employed to predict CFPs, which serve as input for the perturbation theory expressions to calculate the 2nd-rank orthorhombic ZFSPs and to re-analyze optical spectra. Independently SPM is employed to predict the 2nd- and 4th-rank ZFSPs. Correlation of optical and EMR spectroscopy data increases modeling reliability. Comparison of the predicted 2nd-rank ZFSPs with the available experimental ones and consideration of the magnitudes of distortions required to achieve good matching enables discriminating between the substitutional and interstitial sites as location of doped Mn2+ ions. Our study indicates that interstitial sites are more plausible than substitutional sites for Mn2+ ions in TMATC-Zn, in agreement with the experimental prediction. The results reveal the importance of combining two separate methods to determine more reliably the most likely site for substitution of paramagnetic ions. This study also tests the range of applicability of CF theory and SPM analysis for Mn2+ ions in TMATC-Zn crystals and prepares grounds for consideration of the properties of molecular nanomagnets containing Mn2+ ions.

Does Zn mimic diffusion of Al in the HCP Al-Sc-Hf-Ti-Zr high entropy alloys?

The presence of Al in the hexagonal close-packed (HCP) Al-Sc-Hf-Ti-Zr high-entropy-alloy system was previously found to be a primary reason for partial D019 ordering. Since tracer measurements of Al self-diffusion are extremely challenging due to the absence of a suitable radioisotope, in this work, diffusion of Zn as a solute element is investigated for two HCP Al-Sc-Hf-Ti-Zr alloys. The experimental results on diffusion of the 65Zn radioisotope are benchmarked against Al diffusion rates predicted by kinetic Monte Carlo simulations using ab initio-informed calculations of the vacancy formation and migration energies. Furthermore, the partitioning of Zn and the mechanism of Zn diffusion are evaluated. Similarities between Zn and Al diffusion in the investigated HCP Al-Sc-Hf-Ti-Zr alloys are traced back to correlations between the corresponding chemically resolved site substitution energies and migration barriers.

The binding mechanism of benzophenone-type UV filters and human serum albumin: The role of site, number, and type of functional group substitutions

Benzophenone-type UV filters (BPs) are common in natural aquatic environments. They can cause endocrine disruption or other adverse effects once they enter the human body via the food chain or drinking water. The primary cause of BPs accumulation and toxicity is the transport of BPs into the human body. Functional group substitutions can have a significant impact on the interactions of BPs and transporters, resulting in a variety of impact effects. Therefore, we explored the interaction between human serum albumin (HSA, a typical transporter) and ten typical BPs [benzophenone (BP1), 2-hydroxybenzophenone (BP2), 4-hydroxybenzophenone (BP3), 2,2′-dihydroxybenzophenone (BP4), 2,4-dihydroxybenzophenone (BP5), 4,4′-dihydroxybenzophenone (BP6), 2,4,4′-trihydroxybenzophenone (BP7), 2,2′,4,4′-tetrahydroxybenzophenone (BP8), 2-hydroxy-4-methoxybenzophenone (BP9), and 2,2′-dihydroxy-4-methoxybenzophenone (BP10)] to study the role of functional group substitutions in binding. The results showed that BPs could bind to HSA at site 2, with binding constants ranging from 2.01 × 103 to 4.57 × 105 L/mol. Compared to BP1, hydroxyl and methoxy substitutions enhanced the BPs-HSA binding. The combined effect of the number and site of hydroxyl substitution at BPs determined the binding strength between BPs and HSA. It was more accessible to bind HSA when BPs were substituted with para-hydroxyl (4-hydroxyl) groups than with ortho-hydroxyl (2-hydroxyl) groups. Moreover, the additional para-methoxy (4-methoxy) group increased the BP-HSA binding strength by approximately 47 times under the same hydroxyl substitution conditions. Theoretical calculations revealed that functional group substitutions increased the intermolecular binding force by increasing the negative electrostatic potential surface area of BPs, which significantly increased the electrostatic and dispersion forces between the BPs and HSA. This BPs-HSA binding decreased the α-helix of HSA and influenced the ratio of other secondary structures, including β-sheet, β-turn, and random coil of HSA. This study provides a theoretical and experimental foundation for understanding the human health risks associated with BPs.

Cesium-metalloid halide perovskites MBX3 (M1+= Cs; B2+= Si, Ge, Sn, Pb; X–= Cl, Br, I) as semiconductor photovoltaic materials for sustainable renewable-energy applications

With the dawning of 21st century, governments faced three urgent challenges, global economic crisis, energy crisis and global warming. So, the research goals have directed on developing novel renewable-energy technologies as suitable alternative sources of the traditional energy that addresses these problems. Photovoltaic based solar cells technology gives sustainable solutions and depends on inorganic materials with specific properties. Among this family, halide perovskites (MBX3) have been investigated during the last five years. Besides studying their unique properties as flexible structures, high stability, tunable semiconductor band-gap (Eg 2.50 eV), high charge-carrier mobility and large optical absorption, research also seek for promising and multifaceted electroptical applications that give an amazing power efficiency (~24.0 %) in photovoltaic technology. The current challenge is to synthesis MBX3 materials provide suitable properties, include notable chemical stability at high temperatures, high electrical power efficiency, broad emission and tunable semiconducting Eg. Motivated by the site substitution effect, we extended this concept to build a series of cesium-metalloid MBX3 (M1+ = Cs; B2+ = Si, Ge, Sn, Pb; X– = Cl, Br, I), and investigate their structural, stability and optoelectronic properties. We expect these investigations will provide inspiration for an innovation of such MBX3 materials in photovoltaic applications.

Structural, physicochemical and anticancer study of Zn complexes with pyridyl-based thiazolyl-hydrazones

Thiazolyl-hydrazones (THs) exhibit a wide spectrum of biological activity that can be enhanced by complexation with various metal ions. Zn(II) complexes with α-pyridine-1,3-TH ligands may represent an alternative to the standard platinum-based chemotherapeutics. In addition, they show photoluminescence properties and thus can be regarded as multifunctional materials. In this study, we synthesized and characterized three neutral Zn(II) complexes (1–3) with pyridine-based TH ligands HLS1‒3 in order to investigate the influence of the ligands charge on the structure and intermolecular interactions in the solid state, and consequently photophysical properties. The deprotonation of the ligands mainly affects the relative energies of electronic levels in the complexes, compared to cationic counterparts, resulting in similar photoluminescence mechanisms and quantum yields with a small shift in emission energy. The influence of the substitution at the ligands’ periphery on the selected quantum molecular descriptors of the complexes is localized to the substitution site. Also, the substituents did not considerably influence the redox responses of the complexes. However, predominant spectral changes were observed in the course of the first reduction and oxidation processes which caused distinct spectral color changes indicating their possible functionality for electrochromic applications. In addition, complex 1 showed antiproliferative activity with GI50 values below 2 µM on all tested cancer cell lines.

Investigation of the Substitution Site Effect on o-Carborane-Based Chromophores by Anthracene Introduction at the B(3) Position

Abstract o-Carborane-based emitters have been greatly developed over the last ten years. From the viewpoint of molecular symmetry, o-carborane has one type of equivalent carbon and four types of equivalent boron atoms. However, in contrast to the vast research of aryl-modified o-carboranes on the carbon atom of o-carborane, substitution on the boron atom is less investigated. Herein, we introduced an anthracene unit on the B(3) position of o-carborane and explored the substitution position effect by comparison with the previously reported C(1)-substituted regioisomer. Single-crystal structures, optical measurements, and quantum chemical calculation revealed the significant impact of the substitution position, especially in the intramolecular charge transfer (ICT) process.

Structural disorder and distribution of impurity atoms in β-Ga2O3 under boron ion implantation

Gallium oxide (Ga2O3) has recently attracted much attention due to the prospect of its application in power electronics and in other areas. An important task is the development of controlled and reproducible methods for doping this material with various impurities, among which boron is of considerable interest. The regularities of Ga2O3 doping with this isovalent (for Ga) impurity are poorly studied. Even for ion implantation as the most common semiconductor doping method these studies are still at the initial stage. In this work, the structural properties of β-Ga2O3 layers upon boron ion irradiation and subsequent annealing have been studied using X-ray Diffraction, Reflection High-Energy Electron Diffraction, Secondary Ion Mass Spectrometry, as well as theoretical calculations from first principles. Among the most interesting results are the establishment of a strong redistribution of implanted boron during post-implantation annealing and the conclusion about low degree of substitution of gallium sites by boron atoms.

Emergence of Dielectric Properties by Doping of Semi‐Transition Metal in Semiconductor Complex Perovskite Oxide

AbstractThe effect of zinc substitution at the Cu2+ site and germanium substitution at the Ti4+ site in bismuth copper titanate, Bi2/3Cu3Ti4O12, is investigated. Composition with x = 0.05 is synthesized by semi‐wet route in the system Bi2/3Cu3Ti4−xGexO12 (BCTGO) and Bi2/3Cu3−xZnxTi4−xGexO12 (BCZTGO) that are sintered at 1123 K for 8 h. Crystal structure has remained cubic. The phase formations of these ceramics are confirmed by the X‐ray diffraction. The microstructural analysis of the samples is done by scanning electron microscopy and tunneling electron microscopy. Elemental analysis is performed by energy dispersive X‐ray spectroscopy. X‐ray photoelectron spectroscopy suggests that all elements present in these ceramics are in proper oxidation states. The dielectric constant is found high for BCTGO‐0.05 ceramic. The specific capacitances of BCTGO‐0.05 and BCZTGO‐0.05 are found to be 13.05 and 15.7 F g−1, respectively. Optical band gap values (Eg) of BCTGO‐0.05 and BCZTGO‐0.05 ceramics are found as 1.77 and 1.91 eV.

Probing the Local Environment of Al-Substitution into Ferrihydrite Using DFT + U Calculations

Ferrihydrite (Fh) is a poorly crystalline oxyhydroxide that has attracted attention due to its importance in geochemistry, ion mobility, adsorption, and as a precursor for the formation of more crystalline phases such as goethite and hematite. A chemical model for the isomorphic substitution of the Fe sites by Al is proposed. DFT/plane wave calculations have been performed to provide information about the local environment of Al-substitution into Fh. The structural and electronic properties have been investigated in detail. Al prefers to replace the octahedral Fe sites, which has been evidenced by the comparison of the calculated Al K-edge X-ray absorption near-edge structure spectra with the available experimental data. The effect of the increasing ionicity of the system upon Al-substitution to the quadrupolar coupling constant of 27Al NMR and the Mössbauer quadrupole splitting and isomer shift parameters have been investigated. The results indicate that these parameters are affected by the concentration of Fe-substituted sites. Al-substitution increases the band gap dispersion with the formation of Al electronic states in the conduction band. The standard Helmholtz free energy of Al-substitution has been estimated and discussed in detail.

Tuning the Intermediate Valence Behavior in the Zintl Compound Yb14ZnSb11 by Incorporation of RE3+ [Yb14-xRExZnSb11 (0.2 ≤ x ≤ 0.7), RE = Sc, Y, La, Lu and Gd

The solid solutions of Yb14-xRExZnSb11 (RE = Sc, Y, La, Lu, and Gd; 0.2 ≤ x ≤ 0.7) were prepared to probe the intermediate valency of Yb in Yb14ZnSb11. The substitution of Yb with RE3+ elements should reduce or remove the intermediate valency of the remaining Yb ions. Large crystals are grown from Sn-flux, and the structure and magnetic susceptibility are presented. All compounds crystallize in the Ca14AlSb11 structure type and the RE3+ ions show Yb site substitution preferences that correlate with size. Two compositions of Yb14-xYxZnSb11 were investigated [x = 0.38(3), 0.45(3)] by temperature-dependent magnetic susceptibility and the broad feature in magnetic susceptibility measurements at 85 K in pristine Yb14ZnSb11 attributed to valence fluctuation decreases and is absent for x = 0.45(3). In compounds with nonmagnetic RE3+ substitutions (Sc, Y, La, and Lu), temperature-dependent magnetic susceptibility shows a transition from intermediate valency fluctuation toward temperature-independent (Y, La, and Lu) or Curie-Weiss behavior and possibly low temperature heavy Fermion behavior (Sc). In the example of the magnetic rare earth substitution, RE = Gd, the Curie-Weiss-dependent magnetic moment of Gd3+ is consistent with x. Hall resistivity of Yb14-xYxZnSb11 showed that the carrier concentration decreases with x and the signature of the low-T intermediate valence state seen for x = 0 is suppressed for x = 0.38 and gone for x = 0.45.

High Electron Mobility Hot-Exciton Induced Delayed Fluorescent Organic Semiconductors.

The development of high mobility emissive organic semiconductors is of great significance for the fabrication of miniaturized optoelectronic devices, such as organic light emitting transistors. However, great challenge exists in designing key materials, especially those who integrates triplet exciton utilization ability. Herein, dinaphthylanthracene diimides (DNADIs), with 2,6-extended anthracene donor, and 3'- or 4'-substituted naphthalene monoimide acceptors were designed and synthesized. By introducing acceptor-donor-acceptor structure, both materials show high electron mobility. Moreover, by fine-tuning of substitution sites, good integration with high solid state photoluminescence quantum yield of 26%, high electron mobility of 0.02 cm2 V-1 s-1, and the feature of hot-exciton induced delayed fluorescence was obtained in 4'-DNADI. This work opens a new avenue for developing high electron mobility emissive organic semiconductors with efficient utilization of triplet excitons.

High Electron Mobility Hot‐Exciton Induced Delayed Fluorescent Organic Semiconductors

AbstractThe development of high mobility emissive organic semiconductors is of great significance for the fabrication of miniaturized optoelectronic devices, such as organic light emitting transistors. However, great challenge exists in designing key materials, especially those who integrates triplet exciton utilization ability. Herein, dinaphthylanthracene diimides (DNADIs), with 2,6‐extended anthracene donor, and 3′‐ or 4′‐substituted naphthalene monoimide acceptors were designed and synthesized. By introducing acceptor‐donor‐acceptor structure, both materials show high electron mobility. Moreover, by fine‐tuning of substitution sites, good integration with high solid state photoluminescence quantum yield of 26 %, high electron mobility of 0.02 cm2 V−1 s−1, and the feature of hot‐exciton induced delayed fluorescence were obtained in 4′‐DNADI. This work opens a new avenue for developing high electron mobility emissive organic semiconductors with efficient utilization of triplet excitons.

Low prevalence of influenza viruses and predominance of A(H3N2) virus with respect to SARS-CoV-2 during the 2021-2022 season in Bulgaria.

Social distancing, mask-wearing, and travel restrictions during the COVID-19 pandemic have significantly impacted the spread of influenza viruses. The objectives of this study were to analyze the pattern of influenza virus circulation with respect to that of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Bulgaria during the 2021-2022 season and to perform a phylogenetic/molecular analysis of the hemagglutinin (HA) and neuraminidase (NA) sequences of representative influenza strains. Influenza infection was confirmed using real-time reverse transcription polymerase chain reaction in 93 (4.2%) of the 2193 patients with acute respiratory illness tested wherein all detected viruses were subtyped as A(H3N2). SARS-CoV-2 was identified in 377 (24.3%) of the 1552 patients tested. Significant differences in the incidence of influenza viruses and SARS-CoV-2 were found between individual age groups, outpatients/inpatients, and in the seasonal distribution of cases. Two cases of coinfections were identified. In hospitalized patients, the Ct values of influenza viruses at admission were lower in adults aged ≥65 years (indicating higher viral load) than in children aged 0-14 years (p < 0.05). In SARS-CoV-2-positive inpatients, this association was not statistically significant. HA genes of all A(H3N2) viruses analyzed belonged to subclade 3C.2a1b.2a. The sequenced viruses carried 11 substitutions in HA and 5 in NA, in comparison to the vaccine virus A/Cambodia/e0826360/2020, including several substitutions in the HA antigenic sites B and C. This study revealed extensive changes in the typical epidemiology of influenza infection, including a dramatic reduction in the number of cases, diminished genetic diversity of circulating viruses, changes in age, and seasonal distribution of cases.

Corrosion fatigue crack growth in A7N01S−T5 aluminum alloy MIG welded joints

This paper studies the corrosion fatigue crack growth (CFCG) in 3.5 wt% NaCl solution of the local zones of A7N01S−T5 aluminum alloy metal inert gas (MIG) welded joints cut from high−speed train underframes after service lives of 1.8 million km. The results show that the base metal (BM) region exhibits the highest rate of CFCG compared to both the heat−affected zone (HAZ) and the weld metal (WM) zone. Crack features suggest that the corrosion fatigue failure mode of the BM is hydrogen−assisted propagation and that the failure mode for both the HAZ and WM is anodic dissolution. We calculate that the multi−site adsorption and substitution of Cl− on the surface of the passivation film can make the oxygen and aluminum atoms detach from the surface of the passivation film, causing its destruction and allowing the cracks to expand further. Hydrogen is more likely to accumulate and diffuse along the grain boundaries, reducing their strength and causing them to become the most likely orientation for crack propagation. This study provides the new insight into the specific CFCG mechanisms of each zone in aluminum alloy welded joints.

Aptamer-programmable adeno-associated viral vectors as a novel platform for cell-specific gene transfer

Adeno-associated viruses (AAVs) are commonly used for invivo gene therapy. Nevertheless, the wide tropism that characterizes these vectors limits specific targeting to a particular cell type or tissue. Here, we developed new chemically modified AAV vectors (Nε-AAVs) displaying a single site substitution on the capsid surface for post-production vector engineering through biorthogonal copper-free click chemistry. We were able to identify AAV vectors that would tolerate the unnatural amino acid substitution on the capsid without disrupting their packaging efficiency. We functionalized the Nε-AAVs through conjugation with DNA (AS1411) or RNA (E3) aptamers or with a folic acid moiety (FA). E3-, AS1411-, and FA-AAVs showed on average a 3- to 9-fold increase in transduction compared with their non-conjugated counterparts in different cancer cell lines. Using specific competitors, we established ligand-specific transduction. Invivo studies confirmed the selective uptake of FA-AAV and AS1411-AAV without off-target transduction in peripheral organs. Overall, the high versatility of these novel Nε-AAVs might pave the way to tailoring gene therapy vectors toward specific types of cells both for exvivo and invivo applications.

Effect of substitution position of carbazole based conjugated polymers on the photocatalytic hydrogen evolution activities of conjugated polymer/g-C3N4 heterojunction catalysts

Conjugated polymers/Graphitic carbon nitride (g-C3N4) based heterojunctions have been widely investigated in photocatalytic hydrogen Production (PHP). How to design high-performance conjugated polymers matched with g-C3N4 is the critical issue. Here, two linear D-A type conjugated polymers (BSO-S27 and BSO-S36) were synthesized by Suzuki coupling reaction between dibenzothiophene-5,5-dioxide and N-methylcarbazole units. The substitution sites of N-methylcarbazole are 2,7- positions for BSO-S27 and 3,6- positions for BSO-S36, respectively. The different substitution position leads to that BSO-S27 and BSO-S36 exhibit different optical absorption, energy level, and charge transport ability. Through the composition with g-C3N4 nanosheets (CN), BSO-S27/CN and BSO-S36/CN heterojunctions were formed. PHP results demonstrate that both BSO-S27 and BSO-S27/CN exhibit higher hydrogen evolution rate (HER) than BSO-S36 and BSO-S36/CN photocatalysts (BSO-S27: 1783.5 μmol g−1 h−1; BSO-S36: 1112.5 μmol g−1 h−1; BSO-S27/CN: 23078.2 μmol g−1 h−1; BSO-S36/CN: 15732.6 μmol g−1 h−1). And the hydrogen evolution mechanism of BSO-S27/CN and BSO-S36/CN are discussed deeply. These results demonstrate that regulating substitution position is a feasible method to design high-performance conjugated polymers or polymer heterojunctions as photocatalysts.