Magnetic and mössbauer studies on ductile Fe-Cr-Co permanent magnet alloys

Iron-chromium-cobalt alloys possess attractive magnetic properties combined with good formability and hence are identified as technologically important magnetic materials. Alloys with compositions Fe-28·9 Cr-15·6 Co and Fe-28·4 Cr-20·1Co (weight percent) have been studied. Heat-treatment parameters during thermomagnetic treatment viz temperature, time and external magnetic field were optimized with reference to magnetic properties. The fully treated anisotropic alloys develop remanence=11·5–12·0 kilo Gauss, coercivity=600–650 Oersted and energy product=4–4·5 million Gauss Oersted. Electron microscopic and Mössbauer spectroscopic techniques were used to identify the original and transformed phases. During the various stages of the development of the alloy, the changes in mechanical hardness were correlated with magnetic hardness.     

Statistical Learning for Humanoid Robots

The complexity of the kinematic and dynamic structure of humanoid robots make conventional analytical approaches to control increasingly unsuitable for such systems. Learning techniques offer a possible way to aid controller design if insufficient analytical knowledge is available, and learning approaches seem mandatory when humanoid systems are supposed to become completely autonomous. While recent research in neural networks and statistical learning has focused mostly on learning from finite data sets without stringent constraints on computational efficiency, learning for humanoid robots requires a different setting, characterized by the need for real-time learning performance from an essentially infinite stream of incrementally arriving data. This paper demonstrates how even high-dimensional learning problems of this kind can successfully be dealt with by techniques from nonparametric regression and locally weighted learning. As an example, we describe the application of one of the most advanced of such algorithms, Locally Weighted Projection Regression (LWPR), to the on-line learning of three problems in humanoid motor control: the learning of inverse dynamics models for model-based control, the learning of inverse kinematics of redundant manipulators, and the learning of oculomotor reflexes. All these examples demonstrate fast, i.e., within seconds or minutes, learning convergence with highly accurate final peformance. We conclude that real-time learning for complex motor system like humanoid robots is possible with appropriately tailored algorithms, such that increasingly autonomous robots with massive learning abilities should be achievable in the near future.     

Degree-sequenced matching algorithms for input-queued switches

This paper presents a class of algorithms for scheduling packets in input-queued switches. As opposed to previously known algorithms that focus only on achieving high throughput, these algorithms seek to achieve low average delay without compromising the throughput achieved. Packet scheduling in input-queued switches based on the virtual-output-queued architecture is a bipartite graph matching problem wherein ports are represented by vertices and the traffic flows by the edges. The set of matched edges determine the packets that are to be transferred from the input ports to the output ports. Current matching algorithms implicitly prioritize high-degree vertices, i.e., ports with a large number of flows, causing longer delays at ports with a smaller number of flows. Motivated by this observation, we present three matching algorithms based on explicitly prioritizing low-degree vertices and the edges through them. Using both real gateway traffic traces as well as synthetically generated traffic, we present simulation results showing that this class of algorithms achieves a low average delay as compared to other scheduling algorithms of equivalent complexity while still achieving similar throughput. We also show that these algorithms determine the maximum size matching in almost all cases.     

Influence of Coating Parameter and Sintering Atmosphere on the Corrosion Resistance Behavior of Electrophoretically Deposited Composite Coatings

The purpose of this study is to synthesize and characterize nanosized titania (TiO₂), zinc oxide (ZnO), and its composite coating on Ti–6Al–4V to enhance its corrosion protection behavior in Ringer's solution. Nanosized powders of TiO₂ and ZnO was characterized by Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (XRD), and scanning electron microscopy - energy dispersive atomic spectroscopy (SEM-EDAX) analysis. As a result of antibacterial activity, both ZnO and TiO₂/ZnO have produce remarkable inhibition zone on Escherichia coli. The antibacterial activity of composites are due to the combined effect of ZnO on TiO₂. The adherence and surface uniformity of TiO₂/ZnO composite film on titanium implant was examined by optical microscopy and Vickers microhardness test. Corrosion resistant behavior of the coating on titanium implant was investigated by tafel polarization and impedance analysis. The composite coatings on Ti–6Al–4V have produced improved corrosion resistance with a pronounced shift in the anodic corrosion potential (E_corr) with a corresponding less corrosion current density (I_corr) compared to monophase coating. Similar results have been obtained for impedance analysis which indicated a reduction in double layer capacitance (C_dl) and with enhancement in charge transfer resistance (R_ct). These observations suggest improved corrosion resistance property of TiO₂/ZnO composite coating on Ti–6Al–4V.     

On the relationship between absolute and relative fairness bounds

The fairness of scheduling disciplines used in communication networks has frequently been evaluated using one of two fairness measures: the absolute fairness bound (AFB) and the relative fairness bound (RFB). We present a tight bounded relationship between these measures of fairness. The bounds established are exactly reached in the case of many real scheduling disciplines, thus leading to an easy conversion between these two measures. In the case of latency-rate (LR) servers, this also leads to an easy determination of the upper bound on the latency of a flow from the more tractable relative fairness bound of the scheduler. Our results also indicate that in many real contexts, the two measures of fairness approach each other as the number of flows increases, confirming the RFB as an adequate measure of fairness     

Recovery and reutilisation of copper from metal hydroxide sludges

Sludges generated from electroplating wastewaters contain high concentrations of metals. Studies have confirmed that the concentrations of several metals in the sludge exceed that of those found in natural ores. A very good example is in the case of copper. The natural copper ore contains less than 1% of copper, whereas copper precipitate sludges from the electroplating industry may have an average of 5–10% of copper. Thus, they are one of the largest sources of untapped metal-bearing secondary materials amenable to metals recovery. In Malaysia, most of these metal-bearing sludges are disposed in specially engineering landfills, as many of them do not have the proper incentives and recovery technology. Very less metal recovery is being carried out, and there seems to be a huge waste in these valuable metal resources. With regards to that, an experimental study was carried out to develop and optimise a method of copper recovery from metal hydroxide sludges. Sludge samples containing high concentrations of copper were obtained from a local electroplating plant for the study. A procedure based upon mineral acid leaching or solubilisation was carried out. Two different types of acids, hydrochloric acid (HCl) and sulphuric acid (H₂SO₄) were used to compare the extractability of copper. Experiments were conducted at various acid concentrations and temperatures to determine the maximum amount of copper recoverable. From the results obtained, maximum copper (95%) was solubilised using H₂SO₄ of 10 M at temperature 110°C, for a leaching period of 4 h. These copper concentrated solutions were then heated and crystallised to form CuSO₄ crystals. These crystals were then washed with water and purified. They can be then further treated and reutilised in the metallurgical industry. This study introduces a sustainable method of utilising an electroplating sludge containing valuable metals.     

Identification of a class 3 aldehyde dehydrogenase in human saliva and increased levels of this enzyme, glutathione S-transferases, and DT-diaphorase in the saliva of subjects who continually ingest large quantities of coffee or broccoli

Human saliva was tested for the presence of cytosolic class 3 aldehyde dehydrogenase, glutathione S-transferases alpha, mu, and pi, and DT-diaphorase, enzymes that are known to catalyze the biotransformation of many xenobiotics, including some that are carcinogens and some that are antineoplastic agents. Each of these enzymes was found to be present in this fluid. Inducers of these enzymes are known to be abundantly present in the human diet, especially in certain vegetables and fruits. Further investigation revealed that the salivary content of these enzymes rapidly, coordinately, and markedly increased upon daily consumption of relatively large amounts of coffee or broccoli. The enzyme activities of interest rapidly returned to basal levels when these substances were removed from the diet. Given the important role that cytosolic class 3 aldehyde dehydrogenase, the glutathione S-transferases, and DT-diaphorase are thought to play in determining the carcinogenic potential of some cancer-producing agents as well as the cytotoxic potential of some antineoplastic agents, and assuming that their salivary levels reflect their tissue levels, quantification of the salivary content of one or more of these enzymes, a noninvasive and relatively easy undertaking, could be useful in: (a) preliminarily assessing the chemopreventive potential of various diets and drugs; (b) establishing the optimal dose and schedule in Phase I clinical trials for any putatively chemopreventive diets or drugs of interest; and (c) the rational selection and use of chemotherapeutic agents, since several are inactivated, and a few are activated, by these enzymes; alternatively, the antineoplastic agent could be selected first and then a diet that enables the agent to achieve its full therapeutic potential would be selected based on whether high or low enzyme activity would be favorable in that regard. Such measurements may also be useful as an indicator when exposure to carcinogenic/teratogenic/otherwise toxic environmental/industrial/dietary agents that induce these enzymes is suspected.     

Circular dichroism and electron microscopy of a core Y61F mutant of the F1 gene 5 single-stranded DNA-binding protein and theoretical analysis of CD spectra of four Tyr --> Phe substitutions

A core Y61F mutant of the gene 5 single-stranded DNA-binding protein (g5p) of f1 bacterial virus aggregated when expressed from a plasmid, but, after refolding in vitro, it behaved much like wild-type and may be a stability or folding mutant. Circular dichroism (CD) titrations showed the same cooperative polynucleotide binding modes for Y61F and wild-type g5p. There are n = 4 and n congruent with 2.5 modes for binding to poly[d(A)] at low ionic strengths, but n = 4, n = 3, and n congruent with 2-2.5 modes for binding to fd single-stranded viral DNA (fd ssDNA), where n is the number of nucleotides occluded by each bound g5p monomer in a given mode. Y61F g5p has slightly reduced affinity in the n = 4 mode. Electron microscopy showed that Y61F g5p forms left-handed nucleoprotein superhelices indistinguishable from wild-type. Progression from binding to fd ssDNA in the n = 4 to n = 3 to n congruent with 2-2.5 mode is accompanied by an increase in the number of helical turns, an increase from (7.7 +/- 0.3) to (9.5 +/- 0.3) to ( approximately 10-13) g5p dimers per turn, and a decrease in the number of DNA nucleotides per turn. From CD spectra for four of five possible Y --> F g5p mutants, we infer that the fifth tyrosine, Tyr 56, contributes strongly to the CD. Retention of a strong 229 nm CD band in all mutants indicates that all retain elements of the native structure. Spectra of Y26F, Y34F, and Y61F g5p imply limited mobility of the replacement Phe. Comparison of measured with calculated CD spectra also suggests limited mobility for Tyr 26 and Tyr 34 in g5p in solution, and provides new information that the g5p structure in solution may be dominated by Tyr 41 rotamers differing from that stabilized in the crystal.     

Over-expression of glutathione S-transferases, DT-diaphorase and an apparently tumour-specific cytosolic class-3 aldehyde dehydrogenase by Warthin tumours and mucoepidermoid carcinomas of the human parotid gland

A comprehensive biochemical, immunological and histological study was undertaken during different stages of experimental allergic encephalomyelitis (EAE). Wistar rats with EAE induced by sensitization with bovine myelin showed a maximum decrease of body weight 14-16 days post-inoculation (dpi), coincident with the appearance of the paralysis symptom (acute period). Quantitation of some brain components indicated a temporal dissociation among the alterations observed. The higher diminution of myelin basic protein (MBP) occurred at 6 dpi and then increased to reach 21 dpi, a normal value. Also, the activity of 2',3'-cyclic nucleotide 3'-phosphohydrolase was reduced by 40% with respect to control animals only at 6 dpi. The total lipid content was normal; however, among the individual lipids, sulfatides were principally degraded during the acute stage but the amount of cerebrosides was decreased during the recovery period (29-40 dpi). Free cholesterol was similar in both groups of animals, whereas cholesterol esters were detected in EAE animals from 14 to 40 dpi. Central nervous system meningeal and parenchymal infiltration with mononuclear cells was recognized principally at 14 dpi, but some of cells were still present at 40 dpi. Deposits of immunoglobulins in the infiltrated regions as well as in spinal cord motor neurons were observed among 14-29 dpi. Total circulating antibodies to MBP began to increase at 14 dpi, reaching a plateau at 21 dpi and then maintaining this value until 40 dpi. However, the population of anti-MBP antibodies that also recognizes the neuronal protein synapsin was only present at 14 dpi. The present results suggest that the neurological symptoms can be related to some early changes in the myelin membrane followed by alterations involving neuronal structures. The existence of immunological factors against some epitopes in MBP that also recognize a synaptosomal protein might account, at least in part, for the axonal damage and disruption of the normal interneuronal activity in EAE and lead together with the alterations in some specific myelin constituents and the concomitant CNS inflammatory process to the observed hindlimb paralysis.     

Copper(II) ion removal from aqueous solutions using biosorption technology: thermodynamic and SEM–EDX studies

The present study uses biosorption technology to remove copper(II) ions from aqueous solutions. Mature leaves of neem (Azadirachta indica) were developed into powder form of size 32–45 μm and used as the biosorbent, while copper(II) ion solutions were prepared to be used as adsorbates. Parameters varied include copper(II) ion concentration and adsorption temperature. The neem leaf powder (NLP) dosage which was kept constant at 1.0 g L^?1 and pH was between 5 and 6. Adsorption occurred at a high rate initially and reached equilibrium after 50 min. Adsorption seemed to be more favourable at higher temperatures. Optimal temperature was found to be 333 K, with a high adsorption capacity of 146.30 mg g^?1. Thermodynamic studies showed that the system is spontaneous and endothermic in nature, based on the parameters of Gibbs free energy (?G°), biosorption enthalpy (?H°) and biosorption entropy (?S°) obtained, which gave values of ?2.74, 26.70 and 0.07 kJ mol^?1 K^?1, respectively. The adsorption mechanism was found to be predominantly chemisorption. SEM and EDX results show that copper(II) ions were adsorbed on the micropores of NLP. Results indicate that NLP is a suitable biosorbent for removing copper(II) ions from solutions.