Stabilized High-Membered and Phase-Pure 2D All Inorganic Ruddlesden-Popper Halide Perovskites Nanocrystals as Photocatalysts for the CO2 Reduction Reaction.

In contrast to the 2D organic-inorganic hybrid Ruddlesden-Popper halide perovskites (RPP), a new class of 2D all inorganic RPP (IRPP) has been recently proposed by substituting the organic spacers with an optimal inorganic alternative of cesium cations (Cs+ ). Nevertheless, the synthesis of high-membered 2D IRPPs (n > 1) has been a very challenging task because the Cs+ need to act as both spacers and A-site cations simultaneously. This work presents the successful synthesis of stable phase-pure high-membered 2D IRPPs of Csn+1 Pbn Br3n+1 nanosheets (NSs) with n = 3 and 4 by employing the strategy of using additional strong binding bidentate ligands. The structures of the 2D IRPPs (n = 3 and 4) NSs are confirmed by powder X-ray diffraction and high-resolution aberration-corrected scanning transmission electron microscope measurements. These 2D IRPPs NSs exhibit a strong quantum confinement effect with tunable absorption and emission in the visible light range by varying their n values, attributed to their inherent 2D quantum-well structure. The superior structural and optical stability of the phase-pure high-membered 2D IRPPs make them a promising candidate as photocatalysts in CO2 reduction reactions with outstanding photocatalytic performance and long-term stability.

Atomic-Layer Controlled Interfacial Band Engineering at Two-Dimensional Layered PtSe2/Si Heterojunctions for Efficient Photoelectrochemical Hydrogen Production.

Platinum diselenide (PtSe2) is a group-10 two-dimensional (2D) transition metal dichalcogenide that exhibits the most prominent atomic-layer-dependent electronic behavior of "semiconductor-to-semimetal" transition when going from monolayer to bulk form. This work demonstrates an efficient photoelectrochemical (PEC) conversion for direct solar-to-hydrogen (H2) production based on 2D layered PtSe2/Si heterojunction photocathodes. By systematically controlling the number of atomic layers of wafer-scale 2D PtSe2 films through chemical vapor deposition (CVD), the interfacial band alignments at the 2D layered PtSe2/Si heterojunctions can be appropriately engineered. The 2D PtSe2/p-Si heterojunction photocathode consisting of a PtSe2 thin film with a thickness of 2.2 nm (or 3 atomic layers) exhibits the optimized band alignment and delivers the best PEC performance for hydrogen production with a photocurrent density of -32.4 mA cm-2 at 0 V and an onset potential of 1 mA cm-2 at 0.29 V versus a reversible hydrogen electrode (RHE) after post-treatment. The wafer-scale atomic-layer controlled band engineering of 2D PtSe2 thin-film catalysts integrated with the Si light absorber provides an effective way in the renewable energy application for direct solar-to-hydrogen production.

Lithiation-induced fracture of silicon nanowires observed by in-situ scanning electron microscopy.

Silicon is expected to be a useful anode material in lithium ion batteries for future energy storage applications, because of its high theoretical charge storage density of Li+ ions. However, volume expansion due to lithiation fractures the Si anode material, leading to poor cycle stability of battery operation. The approaches to overcome the problem include using Si nanowires to relieve the stress induced by volume expansion and coating a protective layer on the Si anode to prevent delamination. In this study, we use in-situ scanning electron microscopy to monitor the morphological changes of 90 nm thick pristine Si nanowires and the Si nanowires coated with amorphous TiO2, respectively, during electrochemical lithiation. The results of in-situ observation show that both kinds of Si nanowires exhibit a larger thickness after 10 h lithiation and suffer fracture after 25 h. It is also found that the TiO2 layer is not strong enough to prevent Si nanowires from fracture. Since the TiO2 layer can not be elastically deformed, this surface shell fractures earlier in the lithiation process than pristine Si nanowires. Transformation of the crystalline Si nanowires to an amorphous phase and lithium composition detected in the nanowires support that the observed fracture indeed results from lithiation.

Exploring the Origin of Phase-Transformation Kinetics of CsPbI3 Perovskite Nanocrystals Based on Activation Energy Measurements.

Perovskite α-CsPbI3 nanocrystals (NCs) with a high fluorescence quantum yield (QY) typically undergo a rapid phase transformation to a low-QY δ-CsPbI3 phase, thus limiting their optoelectronic applications. In this study, organic molecule hexamethyldisilathiane (HMS) is used as a unique surfactant to greatly enhance the stability of the cubic phase of CsPbI3 NCs (HMS-CsPbI3) under ambient conditions. The reaction kinetics of the phase transformation of CsPbI3 NCs are systemically investigated through in situ photoluminescence (PL), X-ray diffraction, and transmission electron microscope (TEM) measurements under moisture. The activation energy of HMS-CsPbI3 NCs is found to be 14 times larger than that of CsPbI3 NCs capped by olyelamine (OLA-CsPbI3 NCs). According to density functional theory calculations, the bonding between HMS and CsPbI3 NCs is stronger than that between OLA and CsPbI3 NCs, preventing the subsequent phase transformation. Our study presents a clear pathway for achieving highly stable CsPbI3 NCs for future applications.

Prevalence of Congenital Heart Disease Amongst Schoolchildren in Southwest China.

OBJECTIVE: To investigate the prevalence and risk factors of congenital heart disease in Yunnan, China which has diverse ethnic groups. METHODS: This cross-sectional study enrolled 244,023 children from 2010 to 2015. To diagnose CHD, a conventional physical examination was used to screen suspicious cases, which were further confirmed by echocardiography. RESULTS: A total of 1695 children were diagnosed with CHD. The estimated prevalence was 6.94%. Atrial septal defects were the most common cardiac abnormalities. A higher prevalence of CHD was observed with preterm birth, low birth weight, maternal age ≥35 years, and high-altitude regions. The prevalence also showed differences between diverse ethnic groups. CONCLUSIONS: The prevalence of CHD in China may have ethnic differences.

Effect of miR-301a/PTEN pathway on the proliferation and apoptosis of cervical cancer.

The aim of this study was to evaluate the effect of the miR-301a/PTEN pathway in cervical cancer. miR-301a and PTEN expression were measured by quantitative real-time PCR (qRT-PCR) in tissues samples and HeLa cells. PTEN protein level was determined by Western blotting. Dual reporter luciferase assay was performed to validate PTEN as a direct target of miR-301a. The gain- and loss-of function assay was performed by miR-301a overexpression and silencing. Cell proliferation was monitored by cell counting Kit-8 (CCK-8). Cell apoptosis was quantitated by flow cytometry. SPSS was used to analyze the significant difference in the treatments. miR-301a demonstrated a significantly higher expression in cervical carcinoma tissues compared with the paired non-carcinoma tissues ( n = 12), while PTEN expression was found to be significantly lower in cervical carcinoma tissues than their paired non-carcinoma tissues ( n = 12). In addition, PTEN was identified as the direct target of miR-301a. Moreover, overexpression of miR-301a significantly promoted HeLa cells proliferation and anti-apoptosis which had a reverse pattern after PTEN overexpression. Our results confirm PTEN as a direct target of miR-301a in HeLa cells and suggest that miR-301a/PTEN pathway contributes to the development and progression of cervical cancer.

Plan-view transmission electron microscopy specimen preparation for atomic layer materials using a focused ion beam approach.

Using the focused ion beam (FIB) to prepare plan-view transmission electron microscopy (TEM) specimens is beneficial for obtaining structural information of two-dimensional atomic layer materials, such as graphene and molybdenum disulfide (MoS2) nanosheets supported on substrates. The scanning electron microscopy (SEM) image in a dual-beam FIB-SEM can accurately locate an area of interest for specimen preparation. Besides, FIB specimen preparation avoids damages and hydrocarbon contamination that are usually produced in other preparation methods, in which chemical etching and polymer adhesion layers are used. In order to reduce harmful ion-beam bombardment and re-deposition on the thin atomic layers during FIB specimen preparation, we develop a method to protect the atomic layers by making a "microcapsule" to insulate the sample surface. The method is applied respectively to prepare plan-view TEM specimens of a graphene sheet with multiple adlayers and MoS2 atomic layers. Useful electron diffraction results can be obtained from these specimens for understanding the interlayer orientation relationships in the two materials. Auger electron spectroscopy analysis further confirms that the sample surface is free from contamination under the sufficient protection given by the proposed method.

Advanced rechargeable aluminium ion battery with a high-quality natural graphite cathode.

Recently, interest in aluminium ion batteries with aluminium anodes, graphite cathodes and ionic liquid electrolytes has increased; however, much remains to be done to increase the cathode capacity and to understand details of the anion-graphite intercalation mechanism. Here, an aluminium ion battery cell made using pristine natural graphite flakes achieves a specific capacity of ∼110 mAh g-1 with Coulombic efficiency ∼98%, at a current density of 99 mA g-1 (0.9 C) with clear discharge voltage plateaus (2.25-2.0 V and 1.9-1.5 V). The cell has a capacity of 60 mAh g-1 at 6 C, over 6,000 cycles with Coulombic efficiency ∼ 99%. Raman spectroscopy shows two different intercalation processes involving chloroaluminate anions at the two discharging plateaus, while C-Cl bonding on the surface, or edges of natural graphite, is found using X-ray absorption spectroscopy. Finally, theoretical calculations are employed to investigate the intercalation behaviour of choloraluminate anions in the graphite electrode.

Maturation-Based Model of Arrhythmogenic Right Ventricular Dysplasia Using Patient-Specific Induced Pluripotent Stem Cells.

Cellular reprogramming of somatic cells to patient-specific induced pluripotent stem cells (iPSCs) enables in-vitro modeling of human cardiac disorders for pathogenic and therapeutic investigations. However, using iPSC-derived cardiomyocytes (iPSC-CMs) to model an adult-onset heart disease remains challenging because of the uncertainty regarding the ability of relatively immature iPSC-CMs to fully recapitulate adult disease phenotypes. Arrhythmogenic right ventricular dysplasia (ARVD) is an inherited cardiomyopathy characterized by pathological fibrofatty infiltration and cardiomyocyte (CM) loss predominantly in the right ventricle (RV), leading to heart failure and lethal arrhythmias. Over 50% of affected individuals have desmosome gene mutations, most commonly inPKP2encoding plakophilin-2. Using Yamanaka's pluripotent factors, we generated iPSC lines from ARVD patients withPKP2mutations. We first developed a method to induce metabolic maturation of iPSC-CMs and showed that induction of adult-like metabolic energetics from an embryonic/glycolytic state is essential to model an adult-onset cardiac disease using patient-specific iPSCs. Furthermore, we showed that coactivation of normal peroxisome proliferator-activated receptor (PPAR)-α and abnormal PPARγ pathways in ARVD iPSC-CMs resulted in exaggerated CM lipogenesis, CM apoptosis, Na(+)channel downregulation and defective intracellular calcium handling, recapitulating the pathological signatures of ARVD. Using this model, we revealed novel pathogenic insights that metabolic derangement in an adult-like metabolic milieu underlies ARVD pathologies, enabling us to propose novel disease-modifying therapeutic strategies.

Transplantation of umbilical cord and bone marrow-derived mesenchymal stem cells in a patient with relapsing-remitting multiple sclerosis.

There is currently great interest in the use of mesenchymal stem cells as a therapy for multiple sclerosis with potential to both ameliorate inflammatory processes as well as improve regeneration and repair. Although most clinical studies have used autologous bone marrow-derived mesenchymal stem cells, other sources such as allogeneic umbilical cord-derived cells may provide a more accessible and practical supply of cells for transplantation. In this case report we present the treatment of aggressive multiple sclerosis with multiple allogenic human umbilical cord-derived mesenchymal stem cell and autologous bone marrow-derived mesenchymal stem cells over a 4 y period. The treatments were tolerated well with no significant adverse events. Clinical and radiological disease appeared to be suppressed following the treatments and support the expansion of mesenchymal stem cell transplantation into clinical trials as a potential novel therapy for patients with aggressive multiple sclerosis.

Stemness gene expression profile analysis in human umbilical cord mesenchymal stem cells.

Umbilical cord mesenchymal stem cells (UC-MSCs) have several advantages for clinical therapy: the material is easily obtainable, the donation procedure is painless and there is low risk of viral contamination. UC-MSCs play important roles in tissue regeneration, tissue damage repair, autoimmune disease and graft-versus-host disease. In this study, we investigated the normal mRNA expression profile of UC-MSCs, and analyzed the candidate proteins responsible for the signaling pathway that may affect the differentiation characteristics of UC-MSCs. UC-MSCs were isolated by mincing UC samples into fragments and placing them in growth medium in a six-well plate. The immunophenotype characteristics and multilineage differentiation potential of the UC-MSCs were measured by flow cytometry and immunohistochemical assays. In addition, the pathway-focused gene expression profile of UC-MSCs was compared with those of normal or tumorous cells by realtime quantitative polymerase chain reaction. We successfully isolated and cultured UC-MSCs and analyzed the appropriate surface markers and their capacity for osteogenic, adipogenic and neural differentiation. In total, 168 genes focusing on signal pathways were examined. We found that the expression levels of some genes were much higher or lower than those of control cells, either normal or tumorous. UC-MSCs exhibit a unique mRNA expression profile of pathway-focused genes, especially some stemness genes, which warrants further investigation.

Y-chromosome distributions among populations in Northwest China identify significant contribution from Central Asian pastoralists and lesser influence of western Eurasians.

Northwest China is closely adjacent to Central Asia, an intermediate region of the Eurasian continent. Moreover, the Silk Road through the northwest of China once had a vital role in the east-west intercommunications. Nevertheless, little has been known about the genetic makeup of populations in this region. We collected 503 male samples from 14 ethnic groups in the northwest of China, and surveyed 29 Y-chromosomal biallelic markers and 8 short tandem repeats (STRs) loci to reconstruct the paternal architecture. Our results illustrated obvious genetic difference among these ethnic groups, and in general their genetic background is more similar with Central Asians than with East Asians. The ancestors of present northwestern populations were the admixture of early East Asians peopling northwestward and later Central Asians immigrating eastward. This population mixture was dated to occur within the past 10 000 years. The J2-M172 lineages likely entered China during the eastward migration of Central Asians. The influence from West Eurasia through gene flows on the extant ethnic groups in Northwest China was relatively weak.