EXTRACTION OF TRANSITION METALS FROM WOOD PULP FIBERS USING SUPERCRITICAL CARBON DIOXIDE

The supercritical fluid extraction of manganese and iron from solid matrix (wood pulp) is demonstrated experimentally. Supercritical carbon diodixe is used together with lithium bis(trifluoroethyl) dithiocarbonate (FDDC) as the ion-pairing reagent. The metal content of the pulp samples was determined by inductively couple plasma atomic emission spectroscopy (ICP-AES). Optimum conditions were determined to be 30 min each of static and dynamic extraction with 200 atm pressure at 40 °C. Thermomechanical pulp (TMP) extracted under these parameters exhibits an 80% decrease in manganese content, and 91% after a second, sequential extraction. The simultaneous removal of iron was found to be only 6% and supports evidence that it is much more strongly bound to the TMP matrix than manganese.     

Hepatic expression of ErbB3 is repressed by insulin in a pathway sensitive to PI-3 kinase inhibitors

ErbB3 is an epidermal growth factor receptor-related type I tyrosine kinase receptor capable, in conjunction with ErbB2 or epidermal growth factor receptor, of transmitting proliferative and differentiative signals in a variety of cell types. We previously showed that ErbB3 messenger RNA and protein increase in cultured hepatocytes during the first 12 h in culture, as does the binding of heregulin beta1, a ligand for ErbB3. Insulin inhibits the increase in heregulin beta1 binding, as well as the increase in ErbB3 messenger RNA and protein. Two models of insulin deficiency in vivo (diabetes and fasting) demonstrated elevated levels of hepatic ErbB3 protein, strengthening the relevance of our observations in vitro. Using chemical activators or antagonists, we sought to identify the signaling pathways that link insulin to ErbB3 expression. The PI-3 kinase inhibitors, wortmannin and LY294002, completely blocked the inhibition of ErbB3 protein expression by insulin, suggesting a role for PI-3 kinase in the regulation of this growth factor receptor. Rapamycin, an inhibitor of p70 S6 kinase, an enzyme downstream of PI-3 kinase, failed to block the effect of insulin on ErbB3 expression. These results suggest a complex regulatory paradign for ErbB3 that includes PI-3 kinase and may be linked, via insulin, to the metabolic status of the animal.     

Noise performance comparison for third and fourth order cascaded sigma-delta modulators having parameter tolerance errors

A parameter tolerance, signal to noise ratio comparison is made between the MASH third order sigma-delta modulator structure and a new fourth order cascaded structure. The fourth order structure meets the required performance specification with wider parameter tolerances, allowing easier integration using hybrid CMOS technology.<>     

Amidinothiourea as a secondary accelerator in a binary system for the sulphur vulcanization of natural rubber

A study of a binary accelerator system using amidinothiourea as a secondary accelerator with mercaptobenzothiazyl disulfíde (MBTS), in sulphur vulcanization of natural rubber has been undertaken. This system was found to boost MBTS accelerator activity considerably. From the results, a nucleophilic reaction mechanism was established for this system. Different compositions of the amidinothiourea were tried in different mixes using standard recipes, and reference mixes were also vulcanized. Different cure characteristics of the mixes and important physical properties of the vulcanizates were evaluated. Optimum concentrations of amidinothiourea required were derived and the experimental mixes were found to have better cure characteristics, including an advantageous reduction in the optimum cure time. Many of the physical properties of the vulcanizates studied were also found to be better compared to those of the reference mixes. Evaluation of these properties both before and after ageing showed good retention of these properties as well. An attempt was also made to correlate the variation in physical properties to chemical crosslink formation in the various vulcanizates.     

Hydroisomerization of n-hexadecane over Brønsted acid site tailored Pt/ZSM-12

Hydroisomerization of n-hexadecane is performed over ZSM-12 framework having tailored Brønsted acidity to investigate the effect in terms of product selectivity and yield. For this purpose, pure phase of ZSM-12 (bulk molar ratio Si/Al ~ 60) has been synthesized using TEABr as a structure directing agent. The framework Brønsted acidity is tailored with group II elements (M) viz. Ca, Ba and Mg, by means of ion-exchange method. The samples so prepared have been characterized for phase purity, textural parameters, morphology by employing powder X-ray diffraction, nitrogen adsorption–desorption isotherm measurement at 77 K, and scanning electron microscopy technique, respectively. Similarly, % metal exchange is estimated using inductively coupled plasma technique. The quantification of Brønsted acidity for H⁺–M⁺⁺–ZSM-12 samples has been estimated by means of ammonia temperature programmed desorption (NH₃-TPD) and Fourier transform infrared spectroscopy of ammonia (NH₃-FTIR). The well characterized H⁺–M⁺⁺–ZSM-12 samples were loaded with Platinum (Pt, 0.5 wt%) and subjected to hydroisomerization of n-hexadecane using an up-flow fixed bed reactor to verify the effect of process parameters like temperature and WHSV. Pt/H⁺–Ba²⁺–ZSM-12 with tailored Brønsted acidity in the range of about 25 % demonstrated the optimum performance among all the catalysts with an increased isomer selectivity and yield (89.2 and 80.3 %, respectively) by about 4 wt% at a conversion level of about 90 % compared to Pt/H⁺–ZSM-12 framework at 568 K. Such enhancement in isomer selectivity and yield is found to be significant from commercial application point of view. Based on the obtained trend, the potential benefits of implementation of Pt/H⁺–Ba²⁺–ZSM-12 (bulk molar ratio Si/Al ~ 60) framework for cold flow property improvement of ‘bio-ATF’ have been envisaged.     

Synthesis and anti-bacterial activity of novel dihydrochromeno[8,7-e][1,3]oxazine-2(8H)-thiones

A novel series of sulfur-containing dihydrochromeno[8,7-e][1,3]oxazine-2(8H)-thiones has been synthesized through an eco-friendly Mannich-type condensation cyclization reaction of 7-hydroxy-4-methyl-2-thiocoumarin or 6-chloro-7-hydroxy-4-methyl-2-thiocoumarin with formaldehyde and primary amines in water at 80–90°C for 2 h. All the synthesized compounds were screened for their in vitro anti-bacterial efficacy against two Gram-positive and three Gram-negative bacterial strains by using the disc diffusion method. The compound (8c) was found to be most potent with the zone of inhibition of 16 and 15 mm against Staphylococcus aureus ATCC 2937 and Klebsiella pneumoniae ATCC 31488, respectively.     

Small‐Molecule Inhibitors of AF6 PDZ‐Mediated Protein–Protein Interactions

PDZ (PSD‐95, Dlg, ZO‐1) domains are ubiquitous interaction modules that are involved in many cellular signal transduction pathways. Interference with PDZ‐mediated protein–protein interactions has important implications in disease‐related signaling processes. For this reason, PDZ domains have gained attention as potential targets for inhibitor design and, in the long run, drug development. Herein we report the development of small molecules to probe the function of the PDZ domain from human AF6 (ALL1‐fused gene from chromosome 6), which is an essential component of cell–cell junctions. These compounds bind to AF6 PDZ with substantially higher affinity than the peptide (Ile‐Gln‐Ser‐Val‐Glu‐Val) derived from its natural ligand, EphB2. In intact cells, the compounds inhibit the AF6–Bcr interaction and interfere with epidermal growth factor (EGF)‐dependent signaling.     

Propagation Characteristics of Superconducting Slotlines in Vortex State

The propagation characteristics of a slotline structure under the influence of a static magnetic field have been studied using the model developed by Mark W. Coffey and John R. Clem. The complex valued resistive boundary condition formulated using the Coffey and Clem (CC) model is used to modify the dyadic Green’s function in the spectral domain for the slot transmission line. The propagation characteristics are then calculated using the Galerkin’s procedure. The numerical results are presented for propagation parameters and quality factor for a wide range of applied field, reduced temperature and superconducting layer thickness. The increase of the magnetic field and temperature causes an increase in vortex motion which results in a corresponding change in the propagation parameters and quality factor. The variation in the quality factor with respect to the superconducting strip thickness is explained using vortex effects.     

An experimental investigation on the machining characteristics of microscale end milling

This paper discusses an experimental approach to assess the machining characteristics in microscale end milling operation through a systematic experimentation procedure. Microchannels were machined on brass plates using a carbide end mill of 1?mm diameter to analyze the effect of chip load (feed per tooth) and cutting speed on the surface roughness, specific cutting pressure, and cutting forces during microend milling operation. The tangential and radial components of forces were analyzed with the help of a three-dimensional model using the force signals acquired through KISTLER dynamometer. Feed per tooth and the interaction of cutting speed and chip load were identified as the critical parameters affecting the surface roughness of microchannel. Applying the concept of elastic recovery on the side wall surface of microchannels, the minimum chip thickness during the above micromilling operation was evaluated as 0.97???m, and the result was validated by the drastic increase in specific cutting pressure and erratic behavior of cutting forces below a chip load of 1???m.