BEH Amide柱：使碳水化合物的分析更简单、快速、高效

碳水化合物的色谱分析对很多行业的研究来说都是非常重要的工作。例如．食品中单糖与二糖的定性定量,由于复杂糖类．糖醇、人造甜味剂与盐皆可形成复杂基质．使分析变得困难;制药行业通常使用简单或复杂的糖类或糖衍生物基质作为起始药物．通过对药物配方中的这些化合物进行分析,可以为生产提供所需要的信息;     

Bioaccumulation of perfluorochemicals in sediments by the aquatic oligochaete Lumbriculus variegatus

Bioaccumulation of perfluoroalkyl sulfonates, perfluorocarboxylates, and 2-(N-ethylperfluorooctane sulfonamido) acetic acid (N-EtFOSAA) from laboratory-spiked and contaminated field sediments was assessed using the freshwater oligochaete, Lumbriculus variegatus. Semistatic batch experiments were conducted to monitor the biological uptake of these perfluorochemicals (PFCs) over 56 days. The elimination of PFCs was measured as the loss of PFCs in L. variegatus exposed to PFC-spiked sediment for 28 days and then transferred to clean sediment. The resultant data suggest that PFCs in sediments are readily bioavailable and that bioaccumulation from sediments does not continually increase with increasing perfluorocarbon chain length. Perfluorooctane sulfonate (PFOS) and perfluorononanoate were the most bioaccumulative PFCs, as measured by laboratory-based estimated steady-state biota sediment accumulation factors (BSAFs) and BSAFs measured using contaminated field sediments. Elimination rate constants for perfluoroalkyl sulfonates and perfluorocaroboxylates were generally smaller than those previously measured for other organic contaminants. Last, a PFOS precursor, N-EtFOSAA, accumulated in the worm tissues and appeared to undergo biotransformation to PFOS and other PFOS precursors. This suggests that N-EtFOSAA, which has been detected in sediments and sludge often at levels exceeding PFOS, may contribute to the bioaccumulation of PFOS in aquatic organisms.     

Iron(VI) and iron(V) oxidation of thiocyanate

Thiocyanate (SCN-) is used in many industrial processes and is commonly found in industrial and mining waste-waters. The removal of SCN- is required because of its toxic effects. The oxidation of thiocyanate (SCN-) by environmentally friendly oxidants, Fe(VI) and Fe(V), has been studied anaerobically using stopped-flow and premix pulse radiolysis techniques. The stoichiometry with Fe(VI) was determined to be 4HFeO(4-) + SCN(-) + 5H2O-->4Fe(OH)3 + SO4(2-) + CNO(-) + O2 + 2OH-. The rate law for the oxidation of SCN- by Fe(VI) was found to be -d[Fe(VI)]/dt = k11([H+]/([H+] + Ka,HFeO4)) [Fe(VI)][SCN-] where k11 = 2.04 +/- 0.04 x 10(3) M-1 s-1 and pKa,HFeO4 = 7.33. A mechanism is proposed that agrees with the observed reaction stoichiometry and rate law. The rate of oxidation of SCN- by Fe(V) was approximately 3 orders of magnitude faster than Fe(VI). The higher reactivity of Fe(V) with SCN- indicates that oxidations by Fe(VI) may be enhanced in the presence of appropriate one-electron-reducing agents. The results suggest that the effective removal of SCN- can be achieved by Fe(VI) and Fe(V).     

Treatment of saline wastewater contaminated with hydrocarbons by the photo-Fenton process

The application of the photo-Fenton process to the treatment of saline wastewater contaminated with hydrocarbons is investigated. Aqueous saline solutions containing raw gasoline were used as a model oil-field-produced water. The dependence on concentrations of the following reagents has been appropriately evaluated: hydrogen peroxide (100-200 mM), iron ions (0.5-1 mM), and sodium chloride (200-2000 ppm). The reactions were monitored by measurement of the absorption spectra and total organic carbon (TOC). Experimental results demonstrate that the photo-Fenton process is feasible for the treatment of wastewaters containing hydrocarbons, even in the presence of high concentrations of salt. The effect of the salt in this process is described through a series of reactions. A simple feedforward neural network model was found to correlate well the observed data for the degradation process.     

Effects of postchill application of acidified sodium chlorite to control Campylobacter spp. and Escherichia coli on commercial broiler carcasses

Experiments were performed to assess the reduction of Campylobacter spp. and Escherichia coli in commercial broiler carcasses by postchill dip applications of acidified sodium chlorite. Carcass rinses were collected before the inside-outside-bird washer (IOBW), post-IOBW, postchill, and after the postchill application of acidified sodium chlorite. Prevalence and counts of Campylobacter spp. and E. coli were determined. The mean values for Campylobacter spp. and E. coli counts differed significantly at sampling sites. The IOBW reduced the bacterial counts significantly in only one experiment. The chiller reduced Campylobacter counts significantly in both experiments but failed to significantly reduce the counts of E. coli in one experiment. No major reduction in the prevalence after enrichment for Campylobacter spp. was detected post-IOBW or postchill. However, a significant reduction in Campylobacter spp. and in E. coli counts and Campylobacter spp. prevalence was seen after the postchill application of acidified sodium chlorite. These results demonstrate that the antimicrobial effect of acidified sodium chlorite applied postchill may be used to significantly reduce Campylobacter spp. and E. coli in commercial broiler carcasses. Postchill systems may eventually be used in different applications, such as mist, spray, or bath, which could be applied closer to the final stages in processing.     

Effects of sediment characteristics on the toxicity of chromium(III) and chromium(VI) to the amphipod, Hyalella azteca

We evaluated the influence of sediment characteristics, acid-volatile sulfide (AVS) and organic matter (OM), on the toxicity of chromium (Cr) in freshwater sediments. We conducted chronic (28-42-d) toxicitytests with the amphipod Hyalella azteca exposed to Cr(VI) and Cr(III) in water and in spiked sediments. Waterborne Cr(VI) caused reduced survival of amphipods with a median lethal concentration (LC50) of 40 microg/L. Cr(VI) spiked into test sediments with differing levels of AVS resulted in graded decreases in AVS and sediment OM. Only Cr(VI)-spiked sediments with low AVS concentrations (< 1micromol/g) caused significant amphipod mortality. Waterborne Cr(III) concentrations near solubility limits caused decreased survival of amphipods at pH 7 and pH 8 but not at pH 6. Sediments spiked with high levels of Cr(III) did not affect amphipod survival but had minor effects on growth and inconsistent effects on reproduction. Pore waters of some Cr(III)-spiked sediments contained measurable concentrations of Cr(VI), but observed toxic effects did not correspond closely to Cr concentrations in sediment or pore waters. Our results indicate that risks of Cr toxicity are low in freshwater sediments containing substantial concentrations of AVS.     

Psychiatric disorders, familial factors, and cigarette smoking: III. Associations with cessation by young adulthood among daily smokers.

The present study examined whether lifetime psychopathology, regular smoking and psychopathology in family members, and smoking characteristics were associated with successful cessation among daily smokers. A sample of 941 young adults was interviewed for lifetime psychopathology and smoking at three time points; biological parents and siblings were interviewed once for lifetime psychopathology and regular smoking. Within the subset of 242 daily smokers with complete data, most (83%) had tried to quit at least once, although only 22% met our definition of successful cessation (no smoking during the 12 months prior to turning age 25 years). Successful cessation was positively associated with being married and having a higher household income in young adulthood, and negatively associated with lifetime major depressive disorder, elevated antisocial personality disorder symptoms, a family history of drug and alcohol use disorder, and nicotine dependence (for women but not men). Marital status, nicotine dependence (for women but not men), and male gender were significant in multivariate analyses; the effect for major depressive disorder approached significance (p=.052). None of the measures of familial smoking were associated with successful smoking cessation. In conclusion, whereas almost all Axis I disorders in our two previous papers were associated with smoking initiation and progression to daily smoking, major depressive disorder and antisocial personality disorder symptoms were the only psychiatric conditions negatively associated with successful cessation. The causal nature of the significant associations and the degree to which modification of these factors increases the probability of future smoking cessation deserve further attention.     

Metabolic safety-margins do not differ between cows of high and low genetic merit for milk production

Three galactopoietic stimuli, frequent milking (4X), bovine somatotrophin (bST) and thyroxine (T4) were used in an additive stair-step design to achieve maximum output (metabolic capacity) in six peak-lactation cows of high genetic merit (HT) and six of low genetic merit (LT). A further six of each merit were untreated controls (HC, LC). Milk yield was increased significantly by 4X, increased further by the combination of 4X and bST and increased further still and significantly by the full combination of 4X, bST and T4. The magnitude of the yield response to the sequence of treatments did not differ significantly between HT and LT. The yield response to 4X and bST was sustainable without significant loss of body weight or body condition score for the 6 weeks during which these stimuli were administered. The response to the full combination, which included T4, was accompanied by significantly elevated heart rate and significant loss of body weight and condition compared with the combination of 4X and bST. As a result, treatments were discontinued, on an individual cow basis, before completion of this 6-week phase. Time on experiment did not differ between HT and LT. The results do not support the commonly held belief that selective breeding of dairy cows for high milk production has rendered them markedly more susceptible to metabolic disturbances.     

A comparison of drying operations on the rheological properties of whey protein thickening ingredients

An existing procedure for the alteration of whey proteins into a cold‐set thickening agent was modified by developing a spray‐drying operation to replace the prohibitively expensive freeze‐drying step. The original and the modified derivatization procedures were used with a commercial whey protein concentrate (WPC). The freeze‐dried and spray‐dried derivatized WPC powders, along with polysaccharide thickeners, were reconstituted in water and evaluated by using a range of rheological studies. The effects of temperature, concentration, and shear on viscosity as well as the mechanical spectra were assessed to characterize the ability of the powders to function in food systems. Rheological characterization revealed the modified derivatization procedure yielded an ingredient having the same cold‐set thickening and gelling ability as the original derivatized powder. The modified whey proteins were also able to achieve, at higher usage levels, textural properties similar to several polysaccharide thickeners. Use of a spray‐drying technique created a more economical process for the production of a whey protein ingredient that was suitable for contributing viscosity and texture to a wide range of food systems.