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As-synthesized new compound Mn5P4O20H8 show effective removal of heavy metal ions down to the mark of tolerance concentration (parts per billion level) from drinking water with synergistic pathway of surface hydroxyl group trapping and lattice ion-exchange.

A multifunctional modification layer of LiTMPO4 (mainly LiNiPO4) has been uniformly coated onto the surface of LiNi0.8Co0.15Mn0.05O2, and NMC@LTMP2 exhibits good capacity retention of 87% (200 cycles) from 2.8–4.5 V.

Metal cyanamides are an emerging class of functional materials with potential applications in sustainable energy conversion and storage technologies such as catalysis, supercapacitors, photoluminescence and next-gen batteries. The [NCN]2− as the anion, which is isolobal with [O]2− endows metal cyanamides with similar physicochemical properties as oxides and chalcogenides. Whereas the unique quasi-linear structure and electronic resonance between [N C N]2− and [N–C N]2− of [NCN] entity bring out superior properties beyond oxides and chalcogenides. In this review, we present research status, challenges, and the recent striking progress on the metal cyanamides in the synthesis and applications. Specifically, the characteristic structures, physicochemical properties, synthetic methods with corresponding merits/demerits and latest applications in energy conversion and storage of cyanamides are summarized. The detailed outlooks for the new compounds design, morphology manipulation and potential applications are also exhibited.

Optimizing the active sites to balance the conversion and selectivity of the target reaction has long been a challenging quest in developing noble metal-based catalysts. By dispersing Pd and Ru in an amorphous zirconium hydrogen phosphate matrix cross-linked by ionic inorganic oligomers, highly diluted noble metal (0.2 mol%) can be utilized as dual single-atom sites in oxides for the semi-hydrogenation of phenylacetylene with optimized conversion and selectivity (both90%) to styrene. In situ DRIFT-IR results suggested the fast generation of surface hydroxyl groups during the catalytic reaction, indicating the high efficiency of the single-atom sites to dissociate bound H2. This work provides an easily scaled-up method for the production of cost-effective single-atom catalysts extendable to various oxide matrices.

The sluggish rate of the oxygen reduction reaction (ORR) reduces the performance of fuel cell devices. We demonstrated that ordered intermetallic Pd3Bi and Pd31Bi12 are up to ∼11× more active than ...

The design of advanced filter materials to realize worldwide access to clean air and drinking water is of imminent importance. However, complex procedures and toxic raw materials used in the manufacturing process can easily result in secondary pollution, defeating the original purpose. Herein, a green and facile table salt (sodium chloride, NaCl)-assisted pyrolysis strategy is reported to construct nanoporous carbon foam from edible feedstocks (such as agar, pectin, and flour) for use as efficient filter materials. NaCl plays a part in the pore-forming agent and rigid scaffold, which constructs the secondary porous structure while efficiently preventing the self-assembly three-dimensional network structure from thermally collapsing during pyrolysis. Taking advantage of the tailored porous structure, the agar-derived nanoporous carbon foam exhibits a high oil/organic solvent adsorption capacity of up to 202 times its own weight. Besides, an air filtration paper, composed of the obtained material and nonwoven fabric, possesses a PM2.5 filtration efficiency of over 99% with a low-pressure drop of 112 Pa, better than commercial masks. Considering the simple fabrication process and outstanding adsorption/filtration performance, the nanoporous carbon foams fabricated from sustainable precursors have great potential for environment-related applications.

Transition metal dichalcogenides and carbonitrides (TMDs and MXenes) have attracted great attention in electrochemistry due to their tunable electronic structures. Herein, a new compound of Nb2Se2C is designed as a "TMD-MXene"-like material. It exhibits better oxygen evolution reaction performance than most other reported TMDs, MXenes, and commercial electrocatalysts due to the enriched active sites and excellent conductivity.

Heavy metal pollution in water has become one of the main environmental problems in society today. Currently, traditional adsorbents can hardly reduce the heavy metal content in wastewater to trace levels to meet the standards for drinking water. Thus, it is urgent to design and construct new adsorption materials for the effective removal of heavy metals from sewage to trace levels. Herein, functional amorphous phosphated titanium oxide (FAPTO), a new adsorbent containing anchored organic (–NH2/–NH–) and inorganic (–OH) bifunctional groups on the surface, was synthesized via a simple one-pot solvothermal approach. The amino and hydroxyl groups within the matrix offer sorption sites for the capture of heavy metals. The obtained FAPTO effectively adsorbs heavy metals with uptake efficiency reaching 99.0%. FAPTO can remarkably reduce the Pb2+, Cd2+, Cr3+, and Fe3+ concentrations from ppm levels (∼5 mg L−1) to ppb levels (0.001–0.04 mg L−1), reaching the drinking water standards specified by the World Health Organization. Moreover, the Langmuir equilibrium isotherms indicate that the maximum sorption capacities of FAPTO for Pb2+, Cd2+, Cr3+, and Fe3+ are 761.3, 193.3, 255.2, and 166.1 mg g−1, respectively. Importantly, FAPTO possesses excellent reusability with negligible degradation after multiple reuses. The as-prepared FAPTO is a promising absorbent for heavy metal removal by virtue of its outstanding adsorption performance and eco-friendly fabrication process.

Polyvinyl chloride (PVC) is widely used in daily life, but its waste has become a serious environmental problem. A solid base assisted low-temperature solvothermal dehalogenation was developed in this work to sustainably and efficiently transform PVC into high-value dimethylamine hydrochloride (DMACl) chemical and N,O co-doped carbon monolith with hierarchically porous structure. The synergistic promotion of solid-base catalyst and solvent decomposition with the removal of HCl can shift forward the chemical equilibrium to promote the dechlorination of PVC and increase the carbon yield. Meanwhile, the solid-base catalyst can also act as a pore-forming additive to fabricate the carbon monolith with hierarchical pores. Induced by the high specific surface area, hierarchical pores and N,O co-doped structure, the generated carbon monolith exhibits superior electrocatalytic performance towards H

Solution-mediated sequential ion exchange has emerged as a powerful yet simple technique to transform nanoparticulates into a complex architecture. However, the state-of-the-art demonstration of such fine-tailored nanostructures greatly relied on cation exchange reaction because it remains to be a great challenge to apply anion exchange without interfering the original morphology and crystallinity of the target particles. Herein, metal cyanamides with a looser cation sublattice enabled by the quasi-linear [NCN]2– anion units are discovered to be ideal parent compounds to accomplish robust anion exchange reactions. The complete conversion from metal cyanamide nanoparticles to metal chalcogenide nanoparticles (CdNCN to CdS, CdNCN to CdSe, and MnNCN to MnS) is successfully realized by low-temperature reaction in colloidal solution. The nanoparticles retain both the morphology and crystallinity throughout the entire exchange process. In-depth study reveals that the structural similarity in cation packing faci...

The synthesis of alloys with long-range atomic-scale ordering (ordered intermetallics) is an emerging field of nanochemistry. Ordered intermetallic nanoparticles are useful for a wide variety of applications such as catalysis, superconductors, and magnetic devices. However, the preparation of nanostructured ordered intermetallics is challenging in comparison to disordered alloys, hindering progress in material development. Herein, we report a process for converting colloidally synthesized ordered intermetallic PdBi2 to ordered intermetallic Pd3Bi nanoparticles under ambient conditions by electrochemical dealloying. The low melting point of PdBi2 corresponds to low vacancy formation energies, which enables the facile removal of the Bi from the surface while simultaneously enabling interdiffusion of the constituent atoms via a vacancy diffusion mechanism under ambient conditions. The resulting phase-converted ordered intermetallic Pd3Bi exhibits 11 times and 3.5 times higher mass activity and high methanol tolerance for the oxygen reduction reaction compared with Pt/C and Pd/C, respectively, which is the highest reported for a Pd-based catalyst, to the best of our knowledge. These results establish a key development in the synthesis of noble-metal-rich ordered intermetallic phases with high catalytic activity and set forth guidelines for the design of ordered intermetallic compounds under ambient conditions.

At present, some researches have revealed the participation of long noncoding RNAs (lncRNAs) in liver cancer, but few of them have mentioned the role of CRNDE in drug resistance of liver cancer. Hence, this study is conducted to understand the role of CRNDE on liver cancer by regulating microRNA-33a (miR-33a) and high mobility group protein A2 (HMGA2) in liver cancer. First, drug-resistance model (HepG2 and BEL-7402) of human liver cancer cells was established. Then, CRNDE expression in drug-resistant cell lines (HepG2/adriamycin [ADM], BEL-7402/ADM) and parental cell lines (HepG2, BEL-7402) was detected. Furthermore, HepG2/ADM and BEL-7402/ADM cell lines with poor CRNDE expression or miR-33a overexpression was constructed. Next, drug-resistance index was calculated, and cell proliferation, apoptosis, migration, and invasion were detected, respectively. Then, the growth of tumor was observed in nude mice. Finally, the binding relationship between CRNDE and miR-33a and the targeting relationship between miR-33a and HMGA2 were verified. LncRNA CRNDE expressed highly in drug-resistant cells of liver cancer. Downregulated CRNDE and upregulated miR-33a-inhibited cells drug-resistance and promoted their apoptosis in liver cancer drug-resistant cells. CRNDE adsorbing and inhibiting miR-33a to promote HMGA2 in liver cancer drug-resistant cells by acting as a ceRNA. Silencing CRNDE or up-regulating miR-33a inhibited tumor growth of liver cancer in vivo. Our study provides evidence that downregulated CRNDE could upregulate miR-33a and inhibit HMGA2 expression, thus significantly promotes apoptosis of liver cancer cells and inhibiting its proliferation, migration, invasion and drug resistance.

Reservoir relative permeability is greatly important to the development of water flooding reservoirs. Currently, most researches on relative permeability have not taken the roughness of pore surface and actual fluid distributions into consideration. In this paper, a novel relative permeability model for water flooding reservoirs taking the roughness and actual fluid distributions into consideration has been proposed by using the fractal theory. The novel model contains some key parameters, all of which have clear physical meanings, such as the immobile liquid film thickness, relative roughness, tortuosity fractal dimension $$ D_{\text{T}} $$ and pore fractal dimension $$ D_{\text{f}} $$ . The predicted results of the novel fractal relative permeability model are consistent with published experimental data. That verifies the correctness of the novel fractal relative permeability model. Finally, sensitive factor analysis of novel relative permeability model is conducted. We can find that the wetting fluid relative permeability decreases as the immobile wetting fluid film thickness or relative roughness increases. When the tortuosity fractal dimension or pore fractal dimension increases, the wetting relative permeability and non-wetting relative permeability will both decrease. An increase in maximum pore diameter or the decreasing of minimum pore diameter results in the reduction in fractal dimension of flow channel and discontinuous saturation. The increasing of maximum pore diameter results in an increase in the relative permeability of wetting fluid. The minimum pore diameter has tiny effect on the relative permeability.

Overall electrocatalytic water splitting can efficiently and sustainably produce clean hydrogen energy to alleviate the global energy crisis and environmental pollution. Two-dimensional (2D) materials with a unique band structure and surface conformation have emerged as promising electrocatalysts for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). However, the intrinsic activities of primitive 2D materials in the catalytic process are still inferior to those of noble metal-based electrocatalysts. Surface defect engineering can modulate the electronic structure of 2D materials and induce new physicochemical properties, promoting their electrocatalytic performance. Herein, this minireview focuses on some recent developments in surface defect engineering, including the contribution of active sites, the derivation of the heterogeneous interface, and the anchoring of active substances, which provides an effective way to further optimize 2D electrocatalysts for water splitting. Furthermore, the typical morphological characteristics, catalytic activity, stability and catalytic mechanism of these 2D electrocatalysts are introduced. We believe that this minireview will help design more efficient and economical electrocatalysts for overall water splitting.

Transition metal dichalcogenides and carbonitrides (TMDs and MXenes) have attracted great attention in electrochemistry due to their tunable electronic structures. Herein, a new compound of Nb2Se2C is designed as a "TMD-MXene"-like material. It exhibits better oxygen evolution reaction performance than most other reported TMDs, MXenes, and commercial electrocatalysts due to the enriched active sites and excellent conductivity.

Semiconductor nanocrystals of tunable shell/core configurations have great potential in photo-driven applications such as photoluminescence and photocatalysis, but few strategies realize a controllable synthesis with respect to both the size of the core and the shell with high crystallinity. Here, a new synthetic method based on cadmium cyanamide (CdNCN) nanoparticle anion exchange reactions was developed to access solid or hollow CdSe nanocrystals with tunable size and CdNCN@CdS heterostructures with modulated shell/core thickness. The gradual shift and narrow width of photoluminescence features demonstrate the high crystallinity and monodispersity of the resulting CdSe nanocrystals. In the CdNCN@CdS heterostructures, synergistic effects of the photocarrier separation is observed between the CdS shell and CdNCN core, which leads to great improvement in photocatalysis with optimized shell/core ratio.

Semiconductor materials having direct band gaps that overlap well with the solar spectrum are important for a variety of applications in solar energy conversion and optoelectronics. Here, we identify the ternary chalcogenide In4SnSe4 as a direct band gap semiconductor having a band gap of approximately 1.6 eV. In4SnSe4, which contains isolated tetrahedral [SnIn4]8+ clusters embedded in an In–Se framework, was synthesized by precipitation from solution at 300 °C. The In4SnSe4 product consists of microwires having lengths of approximately 5–20 μm and widths of approximately 100–400 nm. Band structure calculations predict a direct electronic band gap of approximately 2.0 eV. Diffuse reflectance UV–visible spectroscopy qualitatively validates the predicted direct band gap, yielding an observed optical band gap of 1.6 eV.

Nanosheet heterostructures that directly interface multiple distinct metal chalcogenides are important two-dimensional materials with unique synergistic properties. Solution routes to these materials offer potential advantages over existing vapor deposition and exfoliation/restacking methods, but they remain difficult to implement and control. Here, we show that SnSe can be grown in solution on micrometer-sized GeSe nanosheets and establish guidelines for achieving controllable deposition. Heating GeSe nanosheets in oleylamine with various amounts of SnCl2 and TOP-Se reveals distinct regimes that favor growth of SnSe on the edge sites vs basal planes of GeSe. Using continuous injection to better control concentrations and reagent delivery, SnSe can be grown on GeSe to produce two distinct types of crystallographically aligned SnSe@GeSe nanosheet heterostructures.

The synthesis of alloys with long range atomic scale ordering (ordered intermetallics) is an emerging field of nanochemistry. Ordered intermetallic nanoparticles are useful for a wide variety of applications such as catalysis, superconductors, and magnetic devices. However, the preparation of nanostructured ordered intermetallics is challenging in comparison to disordered alloys, hindering progress in materials development. We report a process for converting colloidally synthesized ordered intermetallic PdBi2 to ordered intermetallic Pd3Bi nanoparticles under ambient conditions by an electrochemically induced phase transition. The low melting point of PdBi2 corresponds to low vacancy formation energies which enables the facile removal of the Bi from the surface, while simultaneously enabling interdiffusion of the constituent atoms via a vacancy diffusion mechanism under ambient conditions. The resulting phase-converted ordered intermetallic Pd3Bi exhibits 11x and 3.5x higher mass activty and high methanol tolerance for the oxygen reduction reaction compared to Pt/C and Pd/C, respectively,which is the highest reported for a Pd-based catalyst, to the best of our knowledge. These results establish a key development in the synthesis of noble metal rich ordered intermetallic phases with high catalytic activity, and sets forth guidelines for the design of ordered intermetallic compounds under ambient conditions.

Metal alloys with atomic scale ordering (ordered intermetallics) have emerged as a new class of high performance materials for mediating electrochemical reactions. However, ordered intermetallic nanostructures often require long synthesis times and/or high temperature annealing to form because a high-activation energy barrier for interdiffusion must be overcome for the constituent metals to equilibrate into ordered structures. Here we report the direct synthesis of metastable ordered intermetallic Pd31Bi12 at room-temperature in minutes via electrochemical deposition. Pd31Bi12 is highly active for the reduction of O2 to H2O, delivering specific activities over 35× higher than those of commercial Pt and Pd nanocatalysts, placing it as the most active Pd-based catalyst, to the best of our knowledge, reported under similar testing conditions. Stability tests demonstrate minimal loss of activity after 10,000 cycles, and a retention of intermetallic crystallinity. This study demonstrates a new method of preparing ordered intermetallics with extraordinary catalytic activity at room temperature, providing a new direction in catalyst discovery and synthesis.

Molybdenum ditelluride, MoTe2 , is emerging as an important transition-metal dichalcogenide (TMD) material because of its favorable properties relative to other TMDs. The 1T ' polymorph of MoTe2 is particularly interesting because it is semimetallic with bands that overlap near the Fermi level, but semiconducting 2H-MoTe2 is more stable and therefore more accessible synthetically. Metastable 1T '-MoTe2 forms directly in solution at 300 °C as uniform colloidal nanostructures that consist of few-layer nanosheets, which appear to exhibit an approx. 1 % lateral lattice compression relative to the bulk analogue. Density functional theory calculations suggest that small grain sizes and polycrystallinity stabilize the 1T ' phase in the MoTe2 nanostructures and suppress its transformation back to the more stable 2H polymorph through grain boundary pinning. Raman spectra of the 1T '-MoTe2 nanostructures exhibit a laser energy dependence, which could be caused by electronic transitions.

Introducing defects in photocatalytic materials has been considered as an effective method to optimize its performance in the conversion of solar energy to chemical energy. Herein, tin disulfide (SnS2) nanocrystals with high specific surface area and rich sulfur vacancies were successfully synthesized using a low temperature solid state method, and it showed outstanding photocatalytic reduction performance of Cr (VI) aqueous solution under visible light. In addition, the S-vacancy-rich SnS2 (R-SnS2) exhibits a higher visible-light photocurrent and more efficient photoinduced carrier separation than S-vacancy-poor SnS2 (P-SnS2). This discovery provides a new strategy for large-scale preparation of two-dimensional metal sulfides with excellent photocatalytic performance.

We report the colloidal synthesis of substrate-free MoSe2 nanostructures with a uniform flower-like morphology and tunable average diameters that range from approximately 50–250 nm. The MoSe2 nanoflowers contain a large population of highly crystalline few-layer nanosheets that protrude from a central core. Aliquot studies and control experiments indicate that the nanoflowers are generated through a two-step process that involves the formation of a core in the early stages of the reaction followed by outward nanosheet growth that can be controlled based on the concentrations of reagents. The effects of laser-induced local heating, bulk-scale heating using a temperature stage, and nanostructuring on the ability to trigger and tune interlayer decoupling were also investigated. Notably, laser-induced local heating results in dynamic and reversible interlayer decoupling. Such capabilities provide a pathway for achieving quasi-two-dimensional behavior in three-dimensionally structured and colloidally synthesiz...

Recent advances in solar water splitting by using BiVO4 as a photoanode have greatly optimized charge carrier and reaction dynamics, but relatively wide bandgap and poor photostability are still bottlenecks. Here, an excellent photoanode of black BiVO4@amorphous TiO2−x to tackle both problems is reported. Its applied bias photon‐to‐current efficiency for solar water splitting is up to 2.5%, which is a new record for a single oxide photon absorber. This unique core–shell structure is fabricated by coating amorphous TiO2 on nanoporous BiVO4 with the aid of atomic layer deposition and further hydrogen plasma treatment at room temperature. The black BiVO4 with moderate oxygen vacancies reveals a bandgap reduction of ≈0.3 eV and significantly enhances solar utilization, charge transport and separation simultaneously, compared with conventional BiVO4. The amorphous layer of TiO2−x acts as both oxygen‐evolution catalyst and protection layer, which suppresses anodic photocorrosion to stabilize black BiVO4. This configuration of black BiVO4@amorphous TiO2−x may provide an effective strategy to prompt solar water splitting toward practical applications.

Iron–germanium (Fe–Ge) is a complex alloy system that includes several structurally and compositionally diverse phases that exhibit a range of interesting magnetic properties that can change significantly when reduced to nanoscale dimensions. Fe–Ge nanostructures have been synthesized using chemical and physical deposition methods but have not previously been accessible as solution-synthesized colloidal materials. Here, we show that colloidal Fe–Ge nanostructures can be synthesized via the hot injection of an oleylamine solution of Fe(CO)5 into a solution containing GeI4, oleylamine, oleic acid, and hexamethyldisilazane. This approach effectively merges recent advances in the synthesis of colloidal Ge nanocrystals with methods routinely used to synthesize metal and alloy nanoparticles. At 260 °C, spherical nanocrystals of Ni2In-type Fe3Ge2 form. Heating the solution at 300 °C transforms the spherical Fe3Ge2 nanocrystals into CoGe-type FeGe nanowires. The Fe3Ge2 nanocrystals are ferromagnetic with T c ≈ 26...

GeSe is a narrow band gap IV–VI semiconductor that has been attracting increasing attention as a potential alternative material for photovoltaics, along with other optical and electrical applications. However, unlike several other narrow band gap chalcogenide semiconductors, very few examples of GeSe nanostructures have been reported. One-dimensional nanostructures are particularly attractive, because they can serve as building blocks for nanostructured electronic devices. As a step toward both increasing the morphological diversity of GeSe nanomaterials and expanding the library of electronic materials that are accessible as one-dimensional nanostructures, we report here the colloidal synthesis and electrical properties of GeSe nanobelts. The GeSe nanobelts were synthesized by first heating a one-pot reaction mixture of GeI4, TOP-Se, oleylamine, oleic acid, and hexamethyldisilazane to 320 °C, then adding additional TOP-Se and heating for several additional hours. Aliquot studies revealed that an amorphou...

Objective: To investigate the methods for, and clinical outcome of, the operative treatment of thoracolumbar fractures through an approach via the paravertebral muscle (PVM). Methods: From June 2005 to August 2006, 62 patients, comprising 48 men and 14 women with an average age of 45.2 years (range, 21–58) with thoracolumbar fractures without neurological involvement underwent surgical treatment. Twenty-one fractures were located at T12, 24 at L1 and 17 at L2. The study comprised 15 compression and 47 burst fractures with an intact posterior column. Thirty-four cases were selected randomly to undergo surgery through the above approach, while the other 28 cases underwent the traditional procedure. After making a posterior midline incision, which not only facilitates insertion of pedicle screws and fusion of the graft bone at facet joints, but spares the attachment of PVM, the interval between the longissimus and multifidus muscles was undermined. Drainage was not routinely needed and the patients became ambulant with a brace earlier post-operatively. Results: The new approach had statistically significant advantages (P < 0.005) over the traditional one in regard to blood loss, drainage, duration of recumbency and visual analogue scale (VAS), although the time required was almost the same for the two procedures. Till August 2007, 56 patients were successfully followed up for 12 to 26 months (mean, 18.6) and bone fusion was identified in all cases. Neither reduction loss nor loosening or breakage of the fixation occurred. Conclusion: The technique of operating through an approach between the PVM is recommended for thoracolumbar fractures because it is much less invasive, can reduce blood loss and accelerates rehabilitation.

Multi-detector computed tomography (MDCT) has high diagnostic value for detecting or excluding coronary artery stenosis. However, conventional coronary angiograms (CCA) are occasionally required in patients having persistent chest pain with normal MDCT. We retrospectively analyzed 90 patients who underwent CCA due to persistent chest pain with normal MDCT. The patients were classified into patients having more than 50% diameter stenosis in CCA (false negative, group I: n = 14, 62.6 +/- 7.5 years, 7 males) and those having less than 50% diameter stenosis (true negative, group II: n = 76, 52.1 +/- 12.0 years, 42 males). Significant stenosis was observed in 9 patients at the left anterior descending artery, 4 at the right coronary artery, and 1 at the left circumflex artery in group I. Group I patients were older than group II patients (63 +/- 8 versus 52 +/- 12 years, P0.001). There were more patients with hypertension and smoking in group I (64.3% versus 7.9%, 35.7% versus 3.9%, P0.001, P0.001, respectively). The levels of uric acid and homocysteine were higher in group I than in group II (5.7 +/- 1.5 versus 4.6 +/- 1.2 mg/dL, 9.6 +/- 3.1 versus 7.4 +/- 2.5 mol/L, P = 0.008, P = 0.010, respectively). There were more ST or T changes in the electrocardiograms in group I (35.7% versus 1.3%) (P0.001). In multivariate analysis, a history of hypertension, uric acid levels, and ischemic evidence in the electrocardiogram were independent factors for a false negative of MDCT (odds ratio 11.11, 4.76, 1.81, 95% confidence interval 4.67 to 10.00, 1.41 to 1.61, 1.05 to 3.33, P = 0.009, P = 0.012, P = 0.046, respectively). In certain situations, the findings of coronary stenosis by MDCT do not always correlate with that of CCA.

CONSPECTUS: In the wake of the discovery of the remarkable electronic and physical properties of graphene, a vibrant research area on two-dimensional (2D) layered materials has emerged during the past decade. Transition metal dichalcogenides (TMDs) represent an alternative group of 2D layered materials that differ from the semimetallic character of graphene. They exhibit diverse properties that depend on their composition and can be semiconductors (e.g., MoS2, WS2), semimetals (e.g., WTe2, TiSe2), true metals (e.g., NbS2, VSe2), and superconductors (e.g., NbSe2, TaS2). The properties of TMDs can also be tailored according to the crystalline structure and the number and stacking sequence of layers in their crystals and thin films. For example, 2H-MoS2 is semiconducting, whereas 1T-MoS2 is metallic. Bulk 2H-MoS2 possesses an indirect band gap, but when 2H-MoS2 is exfoliated into monolayers, it exhibits direct electronic and optical band gaps, which leads to enhanced photoluminescence. Therefore, it is important to learn to control the growth of 2D TMD structures in order to exploit their properties in energy conversion and storage, catalysis, sensing, memory devices, and other applications. In this Account, we first introduce the history and structural basics of TMDs. We then briefly introduce the Raman fingerprints of TMDs of different layer numbers. Then, we summarize our progress on the controlled synthesis of 2D layered materials using wet chemical approaches, chemical exfoliation, and chemical vapor deposition (CVD). It is now possible to control the number of layers when synthesizing these materials, and novel van der Waals heterostructures (e.g., MoS2/graphene, WSe2/graphene, hBN/graphene) have recently been successfully assembled. Finally, the unique optical, electrical, photovoltaic, and catalytic properties of few-layered TMDs are summarized and discussed. In particular, their enhanced photoluminescence (PL), photosensing, photovoltaic conversion, and hydrogen evolution reaction (HER) catalysis are discussed in detail. Finally, challenges along each direction are described. For instance, how to grow perfect single crystalline monolayer TMDs without the presence of grain boundaries and dislocations is still an open question. Moreover, the morphology and crystal structure control of few-layered TMDs still requires further research. For wet chemical approaches and chemical exfoliation methods, it is still a significant challenge to control the lateral growth of TMDs without expansion in the c-axis direction. In fact, there is plenty of room in the 2D world beyond graphene. We envisage that with increasing progress in the controlled synthesis of these systems the unusual properties of mono- and few-layered TMDs and TMD heterostructures will be unveiled.

A divide-by-16.5 frequency divider, providing read- and write-clocks for an elastic buffer or a gearbox between 10.3125-Gb/s and quad 3.125-Gb/s transceivers in 10-G Ethernet application, is presented. The high-speed and noninteger division is designed by cascading high-speed divide-by-3 followed by divide-by-5.5 which uses double-edge-triggered flip-flops. The divide-by-3 circuit receives and generates 5.15625-GHz and 1.71875-GHz differential clocks with a 50% duty cycle, respectively. Based on current-mode logics (CMLs), the proposed divide-by-16.5 scheme is implemented in a 0.13-/spl mu/m CMOS technology to achieve over 5-GHz operation while consuming 18 mW from a 1.2-V supply.

Most researches of transforming sequential programs into parallel programs have been based on the loop structure transformation method. However, most programs have implicit interprocedure parallelism. This paper suggests a way of extracting parallelism from the loops with procedure calls using the data dependency elimination method. Most parallelization of the loop with procedure calls have been conducted for extracting parallelism from the uniform code. In this paper, we propose interprocedural transformation, which can be apply to both uniform and nonuniform code. We show the examples of uniform, nonuniform, and complex code parallelization. We then evaluated the performance of the various transformation methods using the CRAY-T3E system. The comparison results show that the proposed algorithm out-performs other conventional methods.

Cutting edge: A Cu(2)O jagged polyhedron, with numerous {110} edges and {111} corners, has been developed through a top-down selective oxidative etching process at the expense of the original {111} facet (see figure). The as-prepared nanocrystals exhibited higher photocatalytic activities for the degradation of methylene orange, which may be primarily ascribed to the increased edges and corners.