Narrow Results

The carbon is an important element which belongs to group 14 of the periodic table and shows multiple applications in our daily life as well as at the industrial scale. It is a promising element which represents the liquid–liquid phase transition (LLPT) phenomena. Additionally, it shows interesting anomalous behavior with some usual thermodynamic properties such as heat capacity ($C_p$) near about the liquid–liquid phase coexistence temperature ($T_c$). Hence, it is quite challenging and difficult to simulate carbon at or near the liquid–liquid phase coexistence temperature. This anomalous behavior also creates complications in computing the precise and equilibrated thermodynamic properties close to $T_c$. Therefore, we have studied the thermodynamic behavior of liquid and solid (diamond) states of carbon at liquid–liquid phase coexistence temperature ($T_c$) while transforming from liquid to solid state and achieving the equilibrated liquid and solid states individually. Additionally, we have also performed a similar analysis on melting temperature ($T_m$) to compare the system trends and its thermodynamics behavior in liquid and solid states, respectively. Furthermore, all the predicted thermodynamic results are quite consistent and able to show the equilibrium changes at the liquid–liquid phase coexistence temperature ($T_c$) and melting temperature ($T_m$), respectively.

The formation of point defects in diamond induced by an energetic displacement of a carbon atom out of its lattice site and the relaxation of the thereby disrupted crystal are studied by molecular dynamics simulations with the Tersoff potential. The displacement energy for Frenkel pair creation is calculated to be 52 eV, in agreement with experiments. It is found that the <100> split interstitial, with a bonding configuration which resembles graphite, is the most stable defect, and the disrupted region around it is rich in sp²-like (graphitic) bonds. This region extends several nanometers and is likely to be the elementary electrically conductive cell experimentally found in radiation-damaged diamond.

We present computational aspects of Molecular Dynamics calculations of thermal properties of diamond using the Brenner potential. Parallelization was essential in order to carry out these calculations on samples of suitable sizes. Our implementation uses MPI on a multi-processor machine such as the IBM SP2. Three aspects of parallelization of the Brenner potential are discussed in depth. These are its long-range nature, the need for different parallelization algorithms for forces and neighbors, and the relative expense of force calculations compared to that of data communication. The efficiency of parallelization is presented as a function of different approaches to these issues as well as of cell size and number of processors employed in the calculation. In the calculations presented here, information from almost half of the atoms were needed by each processor even when 16 processors were used. This made it worthwhile to avoid unnecessary complications by making data from all atoms available to all processors. Superlinear speedup was achieved for four processors (by avoiding paging) with 512 atom samples, and 5ps long trajectories were calculated (for 5120 atom samples) in 53 hours using 16 processors; 514 hours would have been needed to complete this calculation using a serial program. Finally, we discuss and make available a set of routines that enable MPI-based codes such as ours to be debugged on scalar machines.

The structural and mechanical properties of 9R diamond and 12R diamond have been investigated by using the first-principles calculations. The elastic constants, bulk modulus and Young’s modulus at various pressures have been investigated. The elastic anisotropy under pressure from 0 to 100 GPa has been studied. From our calculations, we found that 9R diamond and 12R diamond have similar high elastic constants and elastic modulus as lonsdaleite and diamond. The detailed ideal strength calculations show that 9R diamond and 12R diamond are intrinsic superhard materials.

The structural, mechanical and electronic properties of recently reported superhard material C${}_{28}$ are studied by first-principles calculations. The unit cell of C${}_{28}$ is composed of 28 carbon atoms and all sp³ hybridized bonds. From 0 GPa to 100 GPa, C${}_{28}$ satisfies the mechanical stability criteria and the phonon spectrum of C${}_{28}$ has no imaginary frequency, which means that C${}_{28}$ is mechanically and dynamically stable. The results of hardness calculated show that C${}_{28}$ is a potential superhard material with the Vickers hardness of 84.0 GPa. By analyzing the elastic anisotropy, we found that elastic anisotropy of C${}_{28}$ increases with pressure. The calculations of band structure demonstrates that C${}_{28}$ is an indirect bandgap semiconductor with the gap of 4.406 eV. These analyses demonstrate C${}_{28}$ is a superhard semiconductor material.

To explore the practicability of C₆₀ synthesis under extreme conditions (high pressure and high temperature), trinitrotoluene (TNT), trinitramine (RDX) and graphite mixtures of different proportions were detonated in a vacuum container, and the detonation products were collected for detecting. The results of mass spectroscopy, high performance liquid chromatography showed significant signals of C₆₀, which proved that C₆₀ could be synthesized by detonating the mixture of TNT and graphite (in 6:4 and 7:3 mass ratio, respectively), the detonation pressure and temperature were calculated around 13 GPa and 2000 K, respectively. Both experiment results and theoretical analysis showed the importance of detonation pressure and cooling temperature in detonation synthesis of C₆₀.

In this paper, we report strong variations in the Raman spectra of different carbon allotropes samples, for temperatures ranging from 83 K to 1123 K. The temperature dependence of D and G peak frequencies in the Raman spectrum of diamond, graphite, graphene, and carbon nanoparticles (CNPs) with 20 nm dot-size were investigated. These effects caused by temperature can be estimated from the changes in position and in linewidth of peak full width at half maximum (FWHM) G in the Raman spectrum of each sample. The broadening for each allotrope under the same conditions of temperature were: diamond ~ 4 cm^-1, graphite ~ 50 cm^-1, graphene ~ 5 cm^-1 and nanoparticles ~ 7 cm^-1. We also used scanning electron microscopy (SEM) to study the morphology and determine the size of the samples. According to the experimental data, the residual structural disorder and stress present in the samples are enhanced with temperature and responds for the observed changes in the Raman spectra. We present a systematic study of the temperature-dependent Raman spectra of four carbon allotropes.

A systematic investigation of structural, mechanical, elastic anisotropy and electronic properties of a recently reported novel superhard material orthorhombic $C_{20}$ ($o$-$C_{20}$) under pressure is performed utilizing the density functional theory in this work. The crystal structure parameters are obtained at zero as well as at high pressure. Pressure induced elastic constants $C_{ij}$, polycrystalline aggregate elastic modulus $(B,G,E)$, $B/G$ ratio, and Debye temperature changes for $o$-$C_{20}$ have been determined. The crystal elastic anisotropies of the ultra-incompressible $o$-$C_{20}$ are investigated in the pressure range of 0–100 GPa. The Lyakhov–Oganov model is applied to predict the hardness as functions of pressure. The calculated results reveal that $o$-$C_{20}$ possesses high elastic anisotropy under zero pressure and high pressure, and the hardness of $o$-$C_{20}$ decreases with pressure, while the Debye temperature behaves with the opposite trend. The results of electronic structure indicate that $o$-$C_{20}$ exhibits insulator characteristics, and the band gap increases with pressure. This work is expected to provide a useful guide for the future synthesis and application of $o$-$C_{20}$.

This paper reports on the successful deposition of phosphorus (P)-doped n-type (p-C:P) carbon (C) films, and fabrication of n-C:P/p-Si cells by pulsed laser deposition (PLD) using graphite target at room temperature. The cells performances have been given in the dark I–V rectifying curve and I–V working curve under illumination when exposed to AM 1.5 illumination condition (100mW/cm², 25°C). The n-C:P/p-Si cell fabricated using a target with the amount of P by 7 weight percentages (Pwt%) shows the highest energy conversion efficiency η = 1.14% and fill factor FF = 41%. The quantum efficiency (QE) of the n-C:P/p-Si cells are observed to improve with Pwt%. The dependence of P content on the electrical and optical properties of the deposited films and the photovoltaic characteristics of the n-C:P/p-Si heterojunction solar cell are discussed.

The successful deposition of boron (B)-doped p-type (p-C:B) and phosphorous (P)-doped n-type (n-C:P) carbon (C) films, and fabrication of p-C:B on silicon (Si) substrate (p-C:B/n-Si) and n-C:P/p-Si cells by the technique of pulsed laser deposition (PLD) using graphite target is reported. The cells' performances are represented in the dark I–V rectifying curve and I–V working curve under illumination when exposed to AM 1.5 illumination condition (100 mW/cm², 25°C). The open circuit voltage (V_oc) and short circuit current density (J_sc) for p-C:B/n-Si are observed to vary from 230–250 mV and 1.5–2.2 mA/cm², respectively, and to vary from 215–265 mV and 7.5–10.5 mA/cm², respectively, for n-C:P/p-Si cells. The p-C:B/n-Si cell fabricated using the target with the amount of B by 3 Bwt% shows highest energy conversion efficiency, η = 0.20%, and fill factor, FF = 45%, while, the n-C:P/p-Si cell with the amount of P by 7 Pwt% shows highest energy conversion efficiency, η = 1.14%, and fill factor, FF = 41%. The quantum efficiencies (QE) of the p-C:B/n-Si and n-C:P/p-Si cells are observed to improve with Bwt% and Pwt%, respectively. The contributions of QE are suggested to be due to photon absorption by carbon layer in the lower wavelength region (below 750 nm) and Si substrates in the higher wavelength region. The dependence of B and P content on the electrical and optical properties of the deposited films, and the photovoltaic characteristics of the respective p-C:B/n-Si and n-C:P/p-Si heterojunction photovoltaic cells, are discussed.

This paper reports on the successful deposition of boron (B)-doped p-type (p-C:B) and phosphorus (P)-doped n-type (p-C:P) carbon (C) films, and the fabrication of p-C:B on silicon (Si) substrate (p-C:B/n-Si) and n-C:P/p-Si cells by a pulsed laser deposition (PLD) technique using a graphite target at room temperature. The boron and phosphorus atoms incorporated in the films were determined by X-ray photoelectron spectroscopy (XPS) to be in the range of 0.2–1.75 and 0.22–1.77 atomic percentages, respectively. The cells performances have been given in the dark I–V rectifying curve and I–V working curve under illumination when exposed to AM 1.5 illumination conditions (100 mW/cm², 25°C). The open circuit voltage (V_oc) and short circuit current density (J_sc) for p-C:B/n-Si are observed to vary from 230 to 250 mV and from 1.5 to 2.2 mA/cm², respectively; they vary from 215 to 265 mV and from 7.5 to 10.5 mA/cm², respectively, for n-C:P/p-Si cells. The p-C:B/n-Si cell fabricated using the target with the amount of boron by 3 weight percentages (Bwt%) showed the highest energy conversion efficiency, η = 0.20% and fill factor, FF = 45%. The n-C:P/p-Si cell fabricated using the target with the amount of 7 Pwt% showed the highest η = 1.14% and FF = 41%. The quantum efficiency (QE) of the p-C:B/n-Si and n-C:P/p-Si cells were observed to improve with Bwt% and Pwt%, respectively. The contribution of QE in the lower wavelength region (below 750 nm) may be due to photon absorption by the carbon layer, in the higher wavelength region it was due to the Si substrates. In this paper, the dependence of the boron and phosphorus content on the electrical and optical properties of the deposited films and the photovoltaic characteristics of the respective p-C:B/n-Si and n-C:P/p-Si heterojunction solar cells are discussed.

Crystalline cubic silicon carbide (3C-SiC) surface layers have been prepared by carbon-ion implantation into silicon (100) using a MEVVA ion source and subsequent annealing at 1250°C for 2 h. The obtained films have been characterized by SEM, XRD, and micro-Raman analysis. The effect of carbon-ion dose on the surface morphology of the ion-implanted samples has been investigated. Rectangular patterns are observed on the surfaces of carbon-ion-implanted silicon substrates. It is found that the amount of rectangular patterns increases with ion dose, suggesting the dependence of surface morphology on ion dose. The formation of rectangular patterns has been elucidated in this paper.

The Fe–C–H interaction near defects in iron structures was studied using qualitative structure calculations in the framework of the atom superposition and electron delocalization molecular orbital. Calculations were performed using three Fe clusters to simulate an edge dislocation, a divacancy; both in bcc iron and a stacking fault in an fcc iron structure. In all cases, the most stable location for C atom inside the clusters was determined. Therefore, H atom was approximated to a minimum energy region where the C atom resides. The total energy of the cluster decreases when the C atom is located near the defects zone. In addition, the presence of C in the defects zone makes no favorable H accumulation. The C acts as an expeller of H in a way that reduces the hydrogen Fe–Fe bonds weakening.

Recent research has shown that fly ash may catalyze the oxidation of elemental mercury and facilitate its removal. However, the nature of mercury-fly ash interaction is still unknown, and the mechanism of mercury retention in fly ash needs to be investigated more thoroughly. In this work, a fly ash from a coal-fired power plant is used to characterize the inorganic and organic constituents and then evaluate its mercury retention capacities. The as-received fly ash sample is mechanically sieved to obtain five size fractions. Their characteristics are examined by loss on ignition (LOI), scanning electron microscope (SEM), energy dispersive X-ray detector (EDX), X-ray diffraction (XRD), and Raman spectra. The results show that the unburned carbon (UBC) content and UBC structural ordering decrease with a decreasing particle size for the five ashes. The morphologies of different size fractions of as-received fly ash change from the glass microspheres to irregular shapes as the particle size increases, but there is no correlation between particle size and mineralogical compositions in each size fraction. The adsorption experimental studies show that the mercury-retention capacity of fly ash depends on the particle size, UBC, and the type of inorganic constituents. Mercury retention of the types of sp² carbon is similar to that of sp³ carbon.

The solution plasma process (SPP) has attracted considerable attention for the synthesis of carbon nanomaterials; the SPP uses electrical discharges generated directly by a bipolar pulsed power supply for various combinations of the solvents and solutes in the solution. However, the SPP requires high-temperature heat treatment for enhancing conductivity and exhibiting catalyst activity. Furthermore, the metal used as the electrode in the SPP is generally sputtered during discharge. This study presents the feasibility of reducing the heat-treatment step and solving the problem of sputtering of the metal electrodes by simply increasing the repetition frequency of the bipolar pulsed power. During synthesis, the pulse frequency acts as the graphitization catalyst. The enhancement of crystallinity was further confirmed by X-ray diffraction (XRD), Raman spectroscopy, and transmission electron microscopy (TEM). The findings of this study are expected to contribute toward research on improving the properties of carbon for various applications of the SPP synthesis methods.

This study examines the machinability of hybrid fiber metal laminates (HFML), which are made by nickel–chromium alloy (IN-625) metal-cored carbon (Ca)/aramid (Ar) fiber laminate using ultrasonic vibration-coupled microwire electrical discharge machining (UV-$\mu$WEDM). Since UV-$\mu$WEDM parameters significantly impact the erosion rate ($E_R$) and surface undulation ($S_U$), the main objective was to identify the optimal machining parameters. The input variables include the pulse on ($P_{\text{on}}$), pulse off ($P_{\text{off}}$), current ($I_C$), cutting inclination ($C_I$), and servo voltage ($S_V$) coupled with ultrasonic vibration (UV). The empirical findings show that the servo voltage ($S_V$) significantly impacts $E_R$ (73.93%) and $S_U$ (70.02%). The performance categorization order of significant influencing variable is $S_V>P_{\text{off}}>C_I>P_{\text{on}}>I_C$. The desirability interpretation generated the optimum setting for minimizing $S_U$ and maximizing $E_R$ is $P_{\text{on}}=8\mu$s, $P_{\text{off}}=14\mu$s, $S_V=50$V, $I_C=3$A, and $C_I=30^{\circ }$. Scanning electron microscopic (SEM) images were used to perform the micro-interlayer analysis on the machined surface. Moreover, creating an appropriate HFML is necessary to cut various shapes and sizes to satisfy the demands of diverse applications. 60% of components in the aerospace sector are reportedly rejected in real time due to dimension departure, poor surface finish, and damage found in the final assembly. Investigating the viability of cutting-edge machining techniques like UV-$\mu$WEDM is crucial to minimize damage and improve the quality of HFMLs.

Veolia Water Solutions & Technologies receives two prizes at AquaTech China for AnoxKaldnes™ MBBR technology and its Carbon Footprint Reduction Program.

International Consortium Led by Chinese Scientists Announce the First Complete Sequencing of Pear Genome.

Eli Lilly Opens Diabetes Research Center in China.

China 'Soaring Ahead' in Nanotechnology Research.

Latest Genomic Studies Shed New Light on Maize Diversity and Evolution.

Insight Genetics and Kindstar Global Partner to Enhance Cancer Care in China.

Two studies from the Institute of Plant and Microbial Biology published in PNAS show how plants respond to changing environments.

China's Pharmaceuticals Sales Force Levels Surpass US for First Time.

MALAYSIA — Veolia expands presence in East Malaysia.

SINGAPORE — Syneron Dental Lasers signs distribution agreement with Healthcare Solutions & Services Pte Ltd.

SINGAPORE — Fujitsu advances healthcare innovation in collaboration with National University of Singapore.

SINGAPORE — Clearbridge BioMedics makes a big impact at the 2012 Asian Innovation Awards.

SINGAPORE — TauRx Pharmaceuticals receives $111.8m commitment from Genting to prepare for Market Leadership in Alzheimer's.

THAILAND — Key Phase II HIV/HCV trial has commenced in Bangkok.

AUSTRALIA — Hatchtech mechanism of action data and safety study published.

AUSTRALIA — Power to you: carbon nanotube muscles are going strong.

EUROPE — GE Healthcare Life Sciences opens new £3 million laboratories for cell science.

EUROPE — AstraZeneca announces Phase III results from naloxegol pivotal trials.

EUROPE — ACADIA's pimavanserin sees Phase III success.

EUROPE — Big Pharma is doing more for access to medicine in developing countries.

EUROPE — CAVATAK™ bladder cancer – positive preliminary data.

EUROPE — Avita Medical initiates European trial in the management of chronic lower limb ulcers.

NORTH AMERICA — FEI unveils broad correlative microscopy solution set for cell biologists.

NORTH AMERICA — A single dose of Medicago's H5N1 VLP vaccine protects against additional pandemic flu strains in a preclinical study.

NORTH AMERICA — Biologics and stem cell research boost the cell culture market.

Difference in rainfall between wet and dry seasons is increasing worldwide.

Rare carbon molecule detected in dying star gives glimpse of stellar evolution.

Whole genome sequencing of wild rice reveals the mechanisms underlying Oryza genome evolution.

BGI and TGAC join efforts to tackle global challenges in food security, energy and health.

A regeneration system for tartary buckwheat invented by CIB.

A new approach for the reduction of carbon dioxide to methane and acetic acid.

Launch of the Chinese-German Center for Bio-Inspired Materials at the Mainz University Medical Center.

Science: The early bird loses an ovary.

Disruptions of functional brain connectomes in individuals at risk for Alzheimer's disease.

A breakthrough in carbohydrate-based vaccine: One vaccine targets three unique glycan epitopes on cancer cells and cancer stem cells.

BSD Medical signs exclusive agreement for distribution of BSD's cancer treatment hyperthermia system in Taiwan.

Catalent announces major China expansion with two new facilities.

We report on a number of new effects of self-organization at nanoscale, leading to creation of new functional nanomaterials, including carbon and carbon–metal nanotoroids and nanodiscs and self-assembling of magnetic nanoparticles into helices and chains. We also extensively used a new approach of biopattern nanoengineering to create DNA-based complexes with metal or CdSe/ZnS core-shell nanorods (22 × 4.5 nm) which possess strong linearly polarized photoluminescence due to unidirectional orientation of nanorods along DNA filaments. Optical, electrical, and topological (geometrical) properties of such complexes were investigated. This work is a result of a coherent effort (since 1980s) of a consortium of Russian research groups in Nano-technology (INTC: Interdisciplinary Nanotechnology Consortium) aimed at creating molecular electronic devices based on individual and collective properties of specially designed and fabricated nanoclusters.