Orientation of graphitic planes during annealing of “dip deposited” amorphous carbon film: A carbon K-edge X-ray absorption near-edge study

Annealing effect of amorphous carbon thin films on Si(1 0 0) substrates is studied by normal incidence and angle dependent carbon K-edge X-ray absorption near-edge structure (XANES) spectroscopy. The angle dependence of the XANES signal shows that the graphitic basal planes are oriented perpendicular to the surface when the film is annealed at 1000 °C. Micro-Raman spectroscopy reveals two well-separated bands the D band at 1355 cm⁻¹ and G band at ∼1600 cm⁻¹, and their I_D/I_G intensity ratio indicates the formation of more graphitic film at higher annealing temperatures. X-ray diffraction pattern of 1000 °C temperature annealed film confirms the formation of graphite structure.     

Treatment of an Iron-rich ARD Using Waste Carbonate Rock: Bench-Scale Reactor Test Results

The treatment of acid rock drainage (ARD) places extraordinary financial burdens on governments and companies worldwide, and an improved efficiency in treatment by as little as 1% can save many millions of dollars in rehabilitation. We investigated a system for treating Fe-rich ARD using a three-stage reactor design. In the first reaction cell, Fe-rich ARD was partially neutralised using rapid periodic carbonate resuspension with a rotating axial mixer. This was followed by an air-sparged oxidation chamber and then a second reaction cell, with more carbonate periodically resuspended until a pH of 6.3 was reached, which was followed by a settlement chamber. This reactor design has a high capacity for neutralisation, with an efficiency of ≈70% of acidity neutralised by the acid neutralising capacity (g of CaCO₃ equivalent) added to the reactor. Axial mixers were tested because of their low-energy requirements and their high reliability. The intermediate chamber effectively removes Fe by oxidising Fe(II) to Fe(III). Given the amount of acidity neutralised, the sludge volume produced was low compared to other technologies, providing further potential savings in sludge handling. Waste carbonate rock proved to be an effective neutralising agent, even though it was about 60% dolomite and 40% magnesite, with minor calcite, and despite the fact that magnesite has substantially slower dissolution kinetics compared to the more dominant dolomite. The mixed waste carbonates were capable of raising the pH sufficiently to reduce the heavy metal loadings in Fe-rich ARD by more than two orders of magnitude. The final settlement stage of the process was shown to be essential for metal precipitation, for the carry-over of fine carbonates, and CO₂ loss. This was associated with a rise in pH, from 6.3 to 7.5. In addition, residual slow-reacting magnesite from the mixed carbonate remains in the sludge from the first reactor and provides acid buffering capacity within the sludge, which is commonly lacking in the ARD neutralisation sludge of other systems.     

Heat degradation studies of solar heat transfer fluids

Destructive distillation of solar heat transfer fluids was conducted to determine the types of pyrolytic products which might be formed in solar collectors under conditions of stagnation or malfunction. The distillates were analyzed by gas chromatography/mass spectrometry (GC/MS) to determine the types of compounds which were present and the minor components which might be formed. Dehydration products were formed from ethylene and propylene glycols with ethylene oxide and propylene oxide being minor products. A high aromatic petroleum heat transfer fluid yielded distillation fractions enriched in quinolines or isoquinolines and methylated derivatives thereof. Fractionation of this aromatic heat transfer fluid showed that the basic fraction of unheated fluid also contained aza-arenes which exhibited mutagenic activity in the Ames' bioassay. GC/MS showed that the basic fraction from unheated heat transfer fluid also contained benzoquinolines which appeared to be lacking in heat degraded samples of the same fluid. Fractionation of heat transfer fluids, in particular petroleum-based fluids, may often be necessary in order to concentrate minor components so that they can be identified by GC/MS and in order to detect mutagenic activities without interference from cytotoxic components.     

Variational Bayes Based Multiuser Detection for On–Off Random Access Channels

This paper considers on–off random access channels where the users transmit either a one or a zero to a base station or fusion center, and it is assumed that only a small fraction of users are active during any channel use. Under these assumptions, the problem of identifying the active users reduces to that of recovering a sparse binary vector from noisy random linear measurements. A hierarchical Bayesian approach is proposed in this paper to recover the set of active users. A fast approximate Bayesian inference based on Variational Bayes (VB) is then developed. Extensive simulation results are then provided to compare the performance of the proposed VB based Bayesian MUD approach to sparse estimation techniques such as OMP and LASSO. It is observed that the proposed approach is robust to variations in noise as well as sparsity levels. Further, for a given BER performance, the proposed approach requires substantially smaller dimensional codes as compared to OMP and LASSO, thus improving the spectral efficiency.     

Classification of a bacterial isolate, from pozol, exhibiting antimicrobial activity against several gram-positive and gram-negative bacteria, yeasts, and molds

A bacterial isolate, designated CS93, capable of producing a broad-spectrum antimicrobial compound(s) effective against gram-positive and gram-negative bacteria, yeasts, and molds was isolated from pozol, a fermented maize product. This strain was phenotypically similar to another pozol isolate that was previously designated as Agrobacterium azotophilium by other investigators. By using biochemical, phenotypic, and 16S rRNA sequence analysis, both pozol isolates were identified as members of the genus Bacillus, possibly a variant of Bacillus subtilis. While the antimicrobial compound(s) was initially produced only on a solid medium, parameters were identified for production in broth. The compound(s) was heat stable (121 degrees C for 15 min), exhibited activity over a wide pH range (pH 3 to pH 11), and was inactivated by pronase E. The antimicrobial compound(s) was bactericidal and bacteriolytic against Escherichia coli V517, bacteriostatic against Micrococcus luteus, and fungistatic against Saccharomyces cerevisiae. The inhibitory compound(s) could possibly serve as a food biopreservative.     

Intracerebral haemorrhage in a young adult: consider amphetamine abuse

We present the case of a young female who suffered a massive intracerebral bleed following the ingestion of a small quantity of amphetamine (speed). Physicians should be aware that amphetamine abuse can lead to cerebrovascular events in young adults.     

Polyacrylate-coated graphene-oxide and graphene solution via chemical route for various biological application

In this work, we have developed a polyacrylate-coated graphene-oxide and then chemically reduced them into graphene. We found that polyacrylate coating can improve the colloidal stability of both graphene-oxide/graphene. They show good colloidal stability in different aqueous buffer solution with pH ranging from 5 to 10, and these solutions are stable for more than a month. The polyacrylate-coated grapheme oxide/graphene has been characterized by X-ray photoemission spectroscopy (XPS) and micro-Raman spectroscopy. Based on good colloidal stability, this graphene-oxide/graphene is most suitable for the biological application.