Infectious prions in the saliva and blood of deer with chronic wasting disease

A critical concern in the transmission of prion diseases, including chronic wasting disease (CWD) of cervids, is the potential presence of prions in body fluids. To address this issue directly, we exposed cohorts of CWD-na?ve deer to saliva, blood, or urine and feces from CWD-positive deer. We found infectious prions capable of transmitting CWD in saliva (by the oral route) and in blood (by transfusion). The results help to explain the facile transmission of CWD among cervids and prompt caution concerning contact with body fluids in prion infections.     

The ground state of the pseudogap in cuprate superconductors

We present studies of the electronic structure of La(2-x)BaxCuO4, a system where the superconductivity is strongly suppressed as static spin and charge orders or "stripes" develop near the doping level of x = (1/8). Using angle-resolved photoemission and scanning tunneling microscopy, we detect an energy gap at the Fermi surface with magnitude consistent with d-wave symmetry and with linear density of states, vanishing only at four nodal points, even when superconductivity disappears at x = (1/8). Thus, the nonsuperconducting, striped state at x = (1/8) is consistent with a phase-incoherent d-wave superconductor whose Cooper pairs form spin-charge-ordered structures instead of becoming superconducting.     

Porosity and its effect on the digestibility of dilute sulfuric acid pretreated corn stover

Enzyme accessibility has been proposed as a limiting factor in the enzymatic conversion of the cellulose in biomass to glucose. Prior work has shown a strong correlation between porosity, measured as the change in the volume of pores accessible to a cellulase-sized molecule, and the initial digestibility of biomass pretreated by various methods. The goal of this work was to determine if porosity was one of the factors governing the overall enzymatic digestibility of the cellulose in dilute acid pretreated biomass. The porosity of wet pretreated corn stover was determined using the methods of solute exclusion and 1H nuclear magnetic resonance (NMR) thermoporometry. The solute exclusion method identified differences in the accessible pore volume of the pretreated samples compared to untreated corn stover; however, only very small differences in porosity were observed among samples pretreated with a range of severities, giving ethanol yields from 70 to 96%. No correlation was found between the volume accessible to an enzyme-sized molecule (diameter estimated to be 51 A) and the digestibility of the cellulose in dilute acid pretreated corn stover. 1H NMR thermoporometry was used to measure the amount of water in pores ranging from 20 to 200 A. As was the case for the solute exclusion method, a difference was observed in the pore volume of untreated and acid pretreated corn stover, but no significant differences in pore volume were measured for the different pretreated samples.     

饲料中霉菌毒素生物学特性及其检测防治的研究进展

霉菌毒素是毒性很强的霉菌次生代谢产物,是农作物的霉变重要诱因。当被动物体食入、吸入或被皮肤吸收后,霉菌毒素常常会引起机能减退、疾病乃至死亡。导致饲料霉菌毒素污染的原因包括环境因素和饲料生产环节两个方面。高温高湿的环境会促进霉菌毒素的生长旺盛。近十年来因为与人类以及动物的健康和生产密切相关,霉菌毒素的研究不断得到重视。因此,饲料原料有效的、低成本的、快速的检测手段尤为重要。当前方法有使用高效液相色谱(HPLC),薄层色谱法(TLC)。此外,酶联免疫吸附(ELISA)也被应用到快速检测中。荧光偏振免疫法等新方法也逐步被应用,基于红外光谱技术的方法也不断被报导。防治农作物霉变的方法包括提早收割,合理干燥、设备处理和储存加工。此外可以使用化学、生物、脱霉剂等来减少霉菌毒素的危害。     

Growth implants reduced tenderness of steaks from steers and heifers with different genetic potentials for growth and marbling

The objective of this study was to evaluate the effect of growth implants on the carcass characteristics and tenderness of steers and heifers with different genetic potentials for growth, lean meat yield production, and marbling. Two experiments were conducted. Experiment 1 evaluated Angus steers sired by bulls with high EPD for retail product yield or marbling. Implant treatment was imposed randomly within sire groups. Loins (Institutional Meat Purchasing Specifications 180) were collected from each carcass and cut into three 2.54-cm steaks aged for 7, 14 and 21 d to evaluate tenderness. The second experiment evaluated steers and heifers of British and Continental breed descent. Steers and heifers were slaughtered after 120 d on feed. Loin sections were collected, and one 2.54-cm steak aged 7 d was used for tenderness analysis. When implants were used in Angus steers, HCW and LM area increased, whereas internal fat and marbling decreased (P < 0.01). In Angus steers, sire type did not affect shear force values of steaks; however, implant use significantly increased shear force values (P < 0.01). Carcasses from cattle of Continental breed descent were significantly heavier than carcasses of British breed descent with larger LM area, slightly less fat, and a reduced yield grade (P < 0.01). Also, steer carcasses were heavier than heifer carcasses with larger LM (P < 0.05), but no effect of sex on fat depth, internal fat, yield grade or marbling was observed. No significant interactions were seen between growth implant and breed or between growth implant and sex for shear force values. Shear force values were significantly less for steaks from steers and heifers of British decent compared with steers and heifers of Continental descent (P < 0.01). Steaks from implanted steers and heifers had significantly (P < 0.01) greater shear force values than steaks from steers and heifers not implanted. Use of growth implants in growing cattle resulted in significantly heavier carcass weights, larger LM area, and reduced internal fat. However, implant use also reduced the amount of marbling along with contributing to reduced tenderness. Complicating the tenderness issue is the increased shear force values reported for heifers as well as steers of Continental breed descent. Use of implants may contribute to tenderness variability because of different animal responses to implants.     

Mixed-phase oxide catalyst based on Mn-mullite (Sm, Gd)Mn2O5 for NO oxidation in diesel exhaust

Oxidation of nitric oxide (NO) for subsequent efficient reduction in selective catalytic reduction or lean NO(x) trap devices continues to be a challenge in diesel engines because of the low efficiency and high cost of the currently used platinum (Pt)-based catalysts. We show that mixed-phase oxide materials based on Mn-mullite (Sm, Gd)Mn(2)O(5) are an efficient substitute for the current commercial Pt-based catalysts. Under laboratory-simulated diesel exhaust conditions, this mixed-phase oxide material was superior to Pt in terms of cost, thermal durability, and catalytic activity for NO oxidation. This oxide material is active at temperatures as low as 120°C with conversion maxima of ~45% higher than that achieved with Pt. Density functional theory and diffuse reflectance infrared Fourier transform spectroscopy provide insights into the NO-to-NO(2) reaction mechanism on catalytically active Mn-Mn sites via the intermediate nitrate species.