CONCENTRATED ACID CONVERSION OF PINE SOFTWOOD TO SUGARS. PART I: USE OF A TWIN-SCREW REACTOR FOR HYDROLYSIS PRETREATMENT

The first stage of a two-step concentrated sulfuric acid process that converts softwood sawdust to sugars has been explored. The research focuses on the ability of an in-house custom fabricated corotating twin-screw reactor (TSR) to effectively break down and solubilize crystalline cellulose into low molecular weight carbohydrates. Based on design of experiment (DOE) screening results, a four-level, two-factor experimental model building DOE was undertaken. Solid sawdust conversion to liquid, screw torque, and TSR exit pressure were measured or recorded at each experimental condition to yield percent conversion of solids, processed material viscosity, and material energy requirements. Thereafter, model quadratic equations were fitted to the experimental data and found to be statistically significant. Based on data obtained in the DOE the process was optimized to establish a base case operating condition. The acid-treated product made at base case twin-screw operating conditions showed a 38.2% conversion of dry sawdust solids to soluble liquids. The dry solids conversion reduced 73.8% of all hemicellulose and 44.4% of all cellulose to soluble monomers and oligosaccharides.     

Iron enhances generation of fibrin fibers in human blood: Implications for pathogenesis of stroke

Stroke is associated with the intracerebral formation of fibrin clots which may lead to irreversible brain damage. Thrombolytic therapies employ a variety of natural and/or recombinant plasminogen activators to initiate fibrinolytic degradation of cerebral thrombi. However, such therapies when installed beyond 4‐ to 6‐h window, may fail to achieve the expected outcome. This is due to the hydroxyl radical‐induced modification of fibrin(ogen) molecules rendering them refractory to fibrinolytic degradation, but no cause of the increased free radical generation in stroke was offered. Here, we show by means of electron microscopy that iron ions added to human blood dramatically enhances fibrin fibers formation with thrombin, and significantly delays fibrinolysis during spontaneous clotting of native blood. Iron ions caused the appearance dense matted fibrin deposits, similar, if not identical, to those observed in plasma of patients with stroke. These results may explain a known relationship between thrombotic diseases and the increased body concentrations of free iron and/or hemoglobin derivatives. We conclude that any action resulting in the inhibition of hemostatic abnormalities, as well as in the reduction of body free iron and scavenging of hydroxyl radicals (e.g., by polyphenols) can potentially prevent pathological reactions associated with consequences of stroke. Microsc. Res. Tech. 75:1185–1190, 2012. © 2012 Wiley Periodicals, Inc.     

ModerateDrinking.Com and moderation management: Outcomes of a randomized clinical trial with non-dependent problem drinkers.

Objective: To evaluate the effectiveness of a web-based protocol, ModerateDrinking.com (MD; www.moderatedrinking.com) combined with use of the online resources of Moderation Management (MM; www.moderation.org) as opposed to the use of the online resources of MM alone. Method: We randomly assigned 80 problem drinkers to either the experimental or control group with follow-ups at 3, 6, and 12 months. Results: Seventy-five participants (94%) had outcome data at 1 or more follow-up points, and 59 participants (73%) were assessed at all 3 follow-ups. Comparing baseline measures to the average outcomes at follow-ups indicated a significant overall reduction in both groups in alcohol-related problems and consumption variables. Compared with the control group, the experimental group had better outcomes on percent days abstinent. There was an interaction between intensity of drinking at baseline and treatment in determining outcomes assessing drinking. Less heavy drinkers in the experimental group had better outcomes on log mean blood alcohol content (BAC) per drinking day compared with the control group. Heavier drinkers did not differentially benefit from the MD program on this measure. Mixed model analyses in general corroborated these outcomes. Conclusion: The outcome data provide partial evidence for the effectiveness of the MD web application combined with MM, compared with the effectiveness of the resources available online at MM by themselves. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Laser Raman studies of α–bromoacrylamide reactive dyes and wool

The use of laser Raman spectroscopy in the investigation of interactions in α–bromoacrylamide reactive dye–wool fibre systems has been established. The spectra obtained (in particular using C. I. Reactive Red 84) provide some evidence to support the proposal that the dye reacts via addition at the double bond of the reactive group, followed by ring closure through nucleophilic substitution. Furthermore, preliminary studies of the effect of the commercial levelling assistant Albegal B on the aqueous dye environment have been made using C. I. Reactive Yellow 39. The results show that, whilst the primary interaction between the dye and auxiliary may be via the water–solubilising sulphonate groups of the dye, hydrophobic interactions are also important.     

Error correction techniques for high-performance differential A/Dconverters

Error correction techniques that overcome several error mechanism that can affect the accuracy of charge-redistribution analog-to-digital converters (ADCs) are described. A correction circuit and a self-calibration algorithm are used to improve the common-mode rejection of the differential ADC. A modified technique is used to self-calibrate the capacitor ratio errors and obtain higher linearity. The residual error of the ADC due to capacitor voltage dependence is minimized using a quadratic voltage coefficient (QVC) self-calibration scheme. A dual-comparator topology with digital error correction circuitry is used to avoid errors due to comparator threshold hysteresis. A fully differential charge-redistribution ADC implemented with these techniques was fabricated in a 5-V 1-μm CMOS process using metal-to-polysilicide capacitors. The successive-approximation converter achieves 16-b accuracy with more than 90 dB of common-mode rejection while converting at a 200-kHz rate     

Surface plasmon resonance biosensor screening method for paralytic shellfish poisoning toxins: a pilot interlaboratory study

A surface plasmon resonance (SPR) optical biosensor method was developed for the detection of paralytic shellfish poisoning (PSP) toxins in shellfish. This application was transferred in the form of a prototype kit to seven laboratories using Biacore Q SPR optical biosensor instrumentation for interlaboratory evaluation. Each laboratory received 20 shellfish samples across a range of species including blind duplicates for analysis. The samples consisted of 4 noncontaminated samples spiked in duplicate with a low level of PSP toxins (240 μg STXdiHCl equivalents/kg), a high level of saxitoxin (825 μg STXdiHCl/kg), 2 noncontaminated, and 14 naturally contaminated samples. All 7 participating laboratories completed the study, and HorRat values obtained were <1 demonstrating that the method performance was acceptable. Mean recoveries expressed as STXdiHCl equivalents/kg were 94.6 ± 16.8% for the low level PSP toxin mix and 98.6 ± 5.6% for the high level of saxitoxin. Relative standard deviations for within-laboratory variations (RSD(r): repeatability) and between-laboratory variations (RSD(R) = reproducibility) ranged from 1.8 to 9.6% and 2.9 to 18.3% respectively. This first ever reported SPR biosensor interlaboratory study demonstrated this PSP application to be an empowering tool in the drive toward the reduction and replacement of the mouse bioassay within Europe.     

Prophylactic antibiotics in surgery for chronic ear disease

OBJECTIVES/HYPOTHESIS: The role of prophylactic antibiotics in otologic surgery continues to be debated and perhaps misused. Prior studies have provided conflicting evidence with regard to the benefit obtained from the use of prophylactic antibiotics in surgery for chronic otitis media. The current study was designed to evaluate the role of prophylactic antibiotics in the outcomes of surgery for chronic ear disease. It was the authors' impression that there was no indication for prophylactic antibiotics in such surgery. STUDY DESIGN: Randomized prospective study performed in a tertiary care facility. METHODS: Patients who met inclusion criteria (n = 146) were randomly assigned to an antibiotic treatment group or a control group receiving no prophylactic antibiotics. Patients in the antibiotic treatment group were given preoperative intravenous antibiotics followed by oral antibiotics for 5 days after surgery. Patients were followed postoperatively and observed for clinical evidence of infection and graft failure. RESULTS: There was no statistically significant difference between the two groups with regard to the incidence of postoperative infection or graft survival. CONCLUSIONS: The use of prophylactic antibiotics in surgery for chronic ear disease cannot be recommended based on the findings of this study.     

Reduced cardiac contractile responsiveness to isoproterenol in obese rabbits

Although obesity is characterized by increased sympathetic nervous system activity, there is often a paradoxical reduction in cardiovascular end-organ response to sympathetic stimulation. Mechanisms involved in reduced sympathetic responsiveness in obesity have not been well characterized. Therefore, we determined cardiac contractile responsiveness to beta-stimulation in the obese rabbit model using both isolated heart (IH) and isolated papillary muscle (IPM) preparations. Female New Zealand White rabbits were fed control (IH: n=9; IPM: n=6) or 10% fat diets (IH: n=9; IPM: n=7) for 12 weeks. Contractile responsiveness in the IH was determined using a modified Langendorff preparation to evaluate the dose-response relationship between isoproterenol and 1) peak developed pressure/g of left ventricular wet weight and 2) maximal rate of pressure development (+dP/dt/P). Contractile responsiveness in the IPM was determined using right ventricular papillary muscles to evaluate the dose-response relationship between isoproterenol and (1) peak developed tension (T)/mm2 cross-sectional area (CSA) and (2) maximal rate of tension development (dT/dt/CSA). In the IH, baseline and maximum developed pressure/g were reduced in obese rabbits by 37% and 31%, respectively (P< or =.05). In the IPM, baseline and maximum T/CSA responses were reduced in obese rabbits by 59% and 33%, respectively (P< or =.05). Potency of isoproterenol as reflected by the EC50 did not differ between lean and obese animals in either preparation. These results demonstrate that left ventricular contractility in obesity is reduced at baseline and in response to stimulation with isoproterenol and suggest that decreased responsiveness to beta-stimulation may be a factor in the obesity-related systolic dysfunction.     

A high reynolds number rotating disk rheometer

The construction and principles of operation of a rotating disk rheometer are outlined as is its use in the study of polymeric fluid drag reduction. The need for a sensitive measuring system under a wide variation of Reynolds numbers has prompted the development of a computer-controlled system that allows a systematic measurement of the turbulent fluid frictional difference between dilute polymer solutions. Also, the long-term drag-reducing stability of macromolecules in a turbulent flow field can be conveniently measured. Representative data from experimental measurements are presented demonstrating the capabilities of this instrument. © 1994 John Wiley & Sons, Inc.     

Water-soluble copolymers VIII. Synthesis and dilute solution rheological studies of dextran-g-poly(acrylamide-co-sodium acrylates)

Dextran-g-poly(acrylamide-co-sodium acrylates) were prepared by partial hydrolysis of dextran-g-poly(acrylamides) with controlled numbers and lengths of grafted chains. This hydrolysis route proved to be more effective than Ce(IV)-induced cografting of acrylamide and sodium acrylate comonomers onto dextran in producing the desired graft-copolymer structures. The resulting copolymers were characterized and the effects of composition, temperature, ionic strength, and shear rate on dilute solution rheological properties were studied.