In recent years, two-dimensional atomic-level thickness crystal materials have attracted widespread interest such as graphene, hexagonal boron nitride (h-BN), silicene, germanium, black phosphorus (BP), transition metal sulfides and so on. These graphene-like two-dimensional (2D) materials have a lot of excellent characteristics such as high specific surface area and high Young's modulus, and many potential applications in diverse areas such as photo-electricity, catalysts, and transistors. In this review, we introduced the synthesis, structure, properties, and applications of graphene, h-BN, and their heterostructures, especially focused on their mechanical, optical, thermal, electric, and magneticproperties. Finally, we present the outlooks and perspectives for these types of excellent 2D materials and their potential applications. Fig. 42 Schematic of the structures of: (A) an in-plane pressure sensor and (B) a tunnelling pressure sensor. Transmission spectra of: (C) the in-plane sensor and (D) the tunnelling sensor as functions of electron energy with different external pressure. 213This journal is

BackgroundGenetic polymorphism is suggested to be associated with human physical performance. The angiotensin I-converting enzyme insertion/deletion (ACE I/D) polymorphism and the α-actinin-3 gene (ACTN3) R577X polymorphism have been most widely studied for such association analysis. However, the findings are frequently heterogeneous. We aim to summarize the associations of ACE I/D and ACTN3 R577X with sport performance by means of meta-analysis.MethodsWe systematically reviewed and quantitatively summarized published studies, until October 31, 2012, on relationship between ACE/ACTN3 genetic polymorphisms and sports performance, respectively.ResultsA total of 366 articles on ACE and 88 articles on ACTN3 were achieved by literature search. A significant association was found for ACE II genotype compared to D allele carriage (DD+ID) with increased possibility of physical performance (OR, 1.23; 95% CI, 1.05–1.45). With respect to sport discipline, the II genotype was found to be associated with performance in endurance athletes (OR, 1.35; 95% CI, 1.17–1.55). On the other hand, no significant association was observed for ACTN3 RR genotype as compared to X allele carriage (XX+RX) (OR, 1.03; 95% CI, 0.92–1.15). However, when restricted the analyses to power events, a significant association was observed (OR, 1.21; 95% CI, 1.03–1.42).ConclusionOur results provide more solid evidence for the associations between ACE II genotype and endurance events and between ACTN3 R allele and power events. The findings suggest that the genetic profiles might influence human physical performance.

Environmentally friendly and low-cost catalysts are important for the rapid mineralization of organic contaminants in powerful advanced oxidation processes (AOPs). In this study, we reported N-doped graphitic biochars (N-BCs) as low-cost and efficient catalysts for peroxydisulfate (PDS) activation and the degradation of diverse organic pollutants in water treatment, including Orange G, phenol, sulfamethoxazole, and bisphenol A. The biochars at high annealing temperatures (>700 °C) presented highly graphitic nanosheets, large specific surface areas (SSAs), and rich doped nitrogen. In particular, N-BC derived at 900 °C (N-BC900) exhibited the highest degradation rate, which was 39-fold and 6.5-fold of that on N-BC400 and pristine biochar, respectively, and the N-BC900 surpassed most popular metal or nanocarbon catalysts. Different from the radical-based oxidation in N-BC400/PDS via the persistent free radicals (PFRs), singlet oxygen and nonradical pathways (surface-confined activated persulfate-carbon complexes) were discovered to dominate the oxidation processes in N-BC900/PDS. Moreover, the adsorption of organics was determined to be the key step determining reaction rate, revealing that the pre-adsorption of reactants significantly accelerated the nonradical oxidation pathway. This study not only provides robust and cheap carbonaceous materials for environmental remediation but also enables the first insight into the graphitic biochar-based nonradical catalysis.

On the basis of a vertically aligned ultralong Pb(Zr 0.52 Ti 0.48 )O 3 (PZT) nanowire array fabricated using electrospinning nanofibers, we developed a new type of integrated nanogenerator (NG) with ultrahigh output voltage of 209 V and current density of 23.5 μA/cm 2 , which are 3.6 times and 2.9 times of the previous record values, respectively. The output electricity can be directly used to stimulate the frog's sciatic nerve and to induce a contraction of a frog's gastrocnemius. The NG can instantaneously power a commercial light-emitting diode (LED) without the energy storage process. KEYWORDS: Nanogenerator, high output, energy harvesting, PZT nanowires, electrospinning H arvesting clean and renewable energy from the environment is an effective method to response the current energy crisis and power wide distributed nano/microdevices. As a novel energy collector, nanogenerator (NG) exhibits a number of features not shared by the traditional generators, that is, the ones based on ocean tide, river falls, and wind, etc. NG fabricated with piezoelectric nanomaterials can convert tiny and irregular environmental mechanical energy to electricity from sources such as air flowing, heart beating, and so on, which are more popular in our living environment compared to the energy source used for traditional generators as mentioned above.1 Moreover, due to its small size the NG can be effectively integrated with the nano/microscale functional devices to form a self-powered system, which has potential applications in the internet of things, national security, biomedical, and industry areas. In order to improve its output, many attempts have been made ranging from altering piezoelectric materials, that is, ZnO, 14 and so on. Among these systems, many of them need an energy storage unit to make them work properly. This energy storage circuit adds much complexity to the self-powered system and hinders its capacity to work in different tough environments. Here, we report a simple approach of fabricating vertically ultralong Pb(Zr 0.52 Ti 0.48 )O 3 (PZT) nanowire arrays from electrospinning fibers to make a high output NG. Benefiting from the ultralong length of vertical nanowires, the fabricated NG has a maximum output peak voltage of 209 V, which is much higher than the past record of 58 V.2 Also, the NG can output a maximum peak current of 53 μA and current density of 23.5 μA/cm 2 , which is 2.9 times of the recent highest value of 8.13 μA/cm 2 . 15 The output power of our NG can be directly used to stimulate the frog's sciatic nerve and induce a contraction of that frog's gastrocnemius. Moreover, the NG can power a commercial light-emitting diode (LED) instantly without energy storage, which is a considerable progress for the development of selfpowered devices.Previous studies have shown that high piezoelectric coefficient of the fabricating material and integrated parallel and serial connection designs are two major factors to effectively increase NG's output. So, we use PZT, which possesses the highest piezo...

Two excited state proton transfer mechanisms of 3-hydroxyisoquinoline (3HIQ) in cyclohexane and acetic acid (ACID) were investigated based on the time-dependent density functional theory (TDDFT), suggesting a different double-proton transfer mechanism from the one proposed previously (J. Phys. Chem. B, 1998, 102, 1053). Instead of the formation of keto-enol complexes for 3HIQ self-association in cyclohexane, our theoretical results predicted that 3HIQ self-association exists in two forms: the normal form (enol/enol) and the tautomer form (keto/keto) in cyclohexane. A high barrier (37.023 kcal mol(-1)) between the 3HIQ enol monomer and 3HIQ keto monomer form indicated that the 3HIQ keto monomer in the ground state should not exist. In addition, the constructed potential energy surfaces of the ground state and excited state have been used to explain the proton transfer process. Upon optical excitation, the enol/enol form is excited to the first excited state, then transfers one proton, in turn, transition to the ground state to transfer another proton. A relatively low barrier (8.98 kcal mol(-1)) demonstrates two stable structures in the ground state. In view of the acetic acid solvent effect, two protons of 3HIQ/ACID transfer along the dihydrogen bonds in the first excited state, which is a different transfer mechanism to 3HIQ self-association. In addition, the proton transfer process provides a possible explanation for the fluorescence quenching observed.

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Of various chemosensory protocols, the color change observed by the naked eye is considered to be a conceivable and on-site way to indicate the presence of an analyte. We herein designed a ratiometric fluorescence probe by hybridizing dual-emission quantum dots (QDs) and demonstrated its efficiency for on-site visual determination of copper ions. The hybrid probe comprises two sizes of cadmium telluride QDs emitting red and green fluorescence, respectively, in which the red-emitting ones are embedded in silica nanoparticles and the green-emitting ones are covalently linked onto the surface. The fluorescence of the embedded QDs is insensitive to the analyte, whereas the green emissive QDs are functionalized to be selectively quenched by the analyte. Upon exposure to different amounts of copper ions, the variations of the dual emission intensity ratios display continuous color changes from green to red, which can be clearly observed by the naked eye. The limit of detection for copper is estimated to be 1.1 nM, much lower than the allowable level of copper (~20 μM) in drinking water set by U.S. Environmental Protection Agency. The probe is demonstrated for the determination of copper ions in lake water and mineral water samples, especially for visually monitoring copper residues on herb leaves. This prototype ratiometric probe is simple, fully self-contained, and thus potentially attractive for visual identification without the need for elaborate equipment.

External electric field is incorporated into the generalized Mulliken−Hush model and Marcus theory. With this new development, we have investigated the field-dependent electronic structure and rate of photoinduced charge transfer in organic donor−acceptor dyad using timedependent density functional theory and extensive multidimensional visualization techniques. The model is used to evaluate the influence of the external electric field on the electronic coupling between donor and acceptor. The reorganization energy and the free energy change of the electron transfer were calculated. It was found that the major effects in the external electric field dependent rate of the charge transfer originate from changes in the electronic coupling. The new theoretical approach not only promotes a deeper understanding of the connection between the external electric field, chemical structure, and optical and electronic properties of the donor−acceptor system, but also can be used for rational design of novel donor−acceptor system for organic solar cells.