Biologically Relevant Concentrations of Petromyzonol Sulfate,a Component of the Sea Lamprey Migratory Pheromone,Measured in Stream Water

Adult sea lampreys locate spawning streams in the Great Lakes by using a migratory pheromone that is released by stream-resident larval conspecifics. Behavioral, electrophysiological, and biochemical analyses of larval release water have suggested that this pheromone is composed of several components, one of which is petromyzonol sulfate (PS), a known lamprey-specific bile acid. Its precursor, allocholic acid (ACA), has also been implicated. In this study, we employed high-performance liquid chromatography and mass spectrometry to look for both bile acids in various stream waters, thereby testing whether they might have a role in natural pheromone function. Although PS was measured at picomolar concentrations in streams known to contain larval lampreys and attract migratory adults, ACA was not. Neither compound was measured in streams lacking larvae. This finding indicates that PS is a component of the natural pheromone, and it suggests that ACA has little relevance.     

A Sensitive Analytical Method for Quantifying Petromyzonol Sulfate in Water as a Potential Tool for Population Monitoring of the Southern Pouched Lamprey, Geotria Australis, in New Zealand Streams

The migratory southern pouched lamprey, Geotria australis, is a culturally important fish native to New Zealand. Anecdotal evidence suggests that populations of G. australis have declined from historic levels, and presently, this species is rare in many New Zealand rivers and streams. Migratory sea lamprey (Petromyzon marinus) use a pheromone mixture to locate suitable spawning sites. This mixture is comprised of three steroids: petromyzonol sulfate (PS), petromyzonamine disulfate (PADS), and petromyzosterol disulfate (PSDS). We examined the migratory pheromone mixture released by G. australis ammocetes and found that they excrete predominantly PS. PADS has been detected on some occasions in low concentrations, and PSDS either is not released, or is released in extremely low concentrations. By using a recently developed sensitive mass spectrometry method, we compared passive sampling techniques against more traditional active water sampling as methods for estimating lamprey populations in local streams. Passive sampling provided quantitative data for PS from all sites surveyed, with uptake rates of 0.3 to 45.7 pg/day observed. Conversely, active sampling returned only one positive result out of 19 samples, and with a method detection limit of 2.5 × 10^-14 M, this suggests that concentrations of PS in these streams are either extremely low or variable. The combination of passive sampling and triple quadrupole mass spectrometry is a promising tool for monitoring of G. australis in New Zealand streams.     

A Facile Colorimetric Method for Ultra-rapid and Sensitive Detection of Copper Ions in Water

Journal of Inorganic and Organometallic Polymers and Materials - It is of great meaning to develop a facile, reliable and sensitive method to detect copper ions in water. In the study, a facile...     

Rapid and Sensitive Radioscopy for Fine Ceramics Using an Image-Subtraction Method

A new microfocus X-ray testing method has been developed to detect very small defects in ceramic products with high speed and reliability. By using image subtraction, enhanced X-ray images of defects were extracted from the background noise. Much-better sensitivity (e.g., 0.1% in Si₃N₄ that was 20 mm thick) was obtained within a few minutes. This method is considerably superior to the conventional film method. In this study, Si₃N₄ test pieces (penetrameters) that had very small artificial defects (such as slits and pores) were prepared and examined by using the new method.     

高选择性的分光光度法测定水中钙离子浓度

建立了高选择性的分光光度法测定水中钙离子浓度的方法,在p H值为7.0的三乙醇胺缓冲液中,用偶氮胂Ⅲ(ASAⅢ)为显色剂测定水中钙离子浓度。该法线性范围0~200mg/L,平均回收率为100.6%,批内变异系数(CV)和批间变异系数分别为0.83%~2.31%和1.32%~3.27%,与参考方法比较具有良好的相关性,线性回归方程和相关系数分别为Y=1.0044X+0.049,r=0.9990。用该方法测定水中钙离子浓度,具有方法简便、灵敏可靠的优点,适合推广应用。     

水玻璃组成快速测定方法改进

水玻璃的用途十分广泛,几乎遍及到国民经济的各个行业。不同模数的硅酸钠有着不同的用处,而模数作为水玻璃的重要参数,目前其测量的通常方法是分别测出Na2O和SiO2的质量分数然后算出其模数。文章介绍了以溴百里酚蓝指示剂部分取代甲基红指示剂,实现快速测定水玻璃模数的一种新方法,该方法省去了氢氧化钠标准溶液的返滴过程,更加简便、快捷,并详细阐述了该方法的基本原理和实验步骤,计算方法以及相关数据。     

植物性食品中氯丹残留量快速测定方法

建立用气相色谱仪法快速测定植物性食品中氯丹残留量。试样经丙酮提取,正己烷萃取,使用HP-5色谱柱分离,ECD测定。结果表明,顺式氯丹、反式氯丹与氧氯丹能够很好分离,在0．2-100pg,L线性关系良好（r≥O．999）。在2．0-10．0．g／kg的添加水平范围内的平均回收率为82．8％-94．6％,相对标准偏差为2．0％-6．5％。顺式氯丹、反式氯丹与氧氯丹该方法检出限均为0．5gg／kg。     

Fluorescent Gold Nanoprobes for the Sensitive and Selective Detection for Hg

A simple, cost-effective yet rapid and sensitive sensor for on-site and real-time Hg²⁺ detection based on bovine serum albumin functionalized fluorescent gold nanoparticles as novel and environmentally friendly fluorescent probes was developed. Using this probe, aqueous Hg²⁺ can be detected at 0.1 nM in a facile way based on fluorescence quenching. This probe was also applied to determine the Hg²⁺ in the lake samples, and the results demonstrate low interference and high sensitivity.     

Analytical Tools for Rapid,Sensitive, Quantitative Identification of Potential Meat Quality Markers

Myofibrillar extracts from bovine Musculus longissimus dorsi (MLD) were subjected to SDS‐PAGE, electroblotted and fragments of the 30 kDa band determined by internal and N‐terminal Edman sequencing, giving unequivocal proof, troponin‐T (TNT) to be the origin of this band. Based on the N‐terminal primary sequence of the 30 kDa band, a peptide with high antigenic sites was synthesized, conjugated to keyhole limpet hemocyanin (KLH), antibodies were generated and an enzyme‐linked immunosorbent assay (ELISA) was developed for the determination of TNT concentrations in meat samples. For routine determinations of meat quality markers it seems more convenient to analyse soluble meat extracts, produced by trichloroacetic acid (TCA) or HCl treatment. In the supernatants of TCA‐treated MLDs, prominent peptide fragments from glyceraldehyde‐3‐phosphate dehydrogenase and TNT (16—31) could be separated by HPLC and identified by Edman degradation. Both fragments were found to increase with ageing and might become useful indicators of meat quality. After HPLC separation and structure elucidation of MLD HCl extracts, fructose biphosphate aldolase, creatine kinase, glyceraldehyde‐3‐phosphate dehydrogenase and myoglobin could be identified, further potential candidates to correlate their quantitative appearance with meat quality. These peptides and proteins, found in soluble meat extracs, can be analyzed in an automatic, rapid, convenient way either by immunoassay methods, capillary electrophoreses or HPLC, for sure preferable compared to the tedious, inconvenient, time‐consuming method of SDS‐PAGE, also not suitable for automation.     

一种快速测定铜离子的方法

0前言铜离子的分析方法要求简便、快速、准确和低成本,常用方法有:配位滴定法、催化光度法、催化显色光度法等[1-3]。这些方法测定条件较苛刻,应用范围受到一定的限制。另外,还有原子吸收光谱法和     

Rapid Method of Determination of Sorption Isotherms and Water Apparent Diffusivity

In the context of a research on the quality of pasta made from soft wheat, reaction kinetics had to be measured at definite temperatures and water contents. It was chosen to realize such experiments in a pilot dryer. To be able to fix temperature and water content of product for a definite period of time, it was first necessary to determine sorption curves of pasta and a drying model including the values of apparent diffusivity of water at elevated temperatures.

This paper presents a method to meet these objectives. It consists in realizing a sequence of plateaux of air relative humidities of decreasing values, at constant temperature, in the dryer. Air-product equilibrium at the end of each plateau would have been too long to attain, therefore equilibrium product water content was calcultated using an exponential model. Apparent water diffusivity was determined by adjustement of a diffusive model, taking in account that the air humidity change from one plateau to the next one was a linear ramp and not a step-wise change.

The average relative repeatability of equilibrium water Content is 0.1% water/dry basis. There is more dispersion on apparent diffusivity.     

Rapid Method of Determination of Sorption Isotherms and Water Apparent Diffusivity

ABSTRACT

In the context of a research on the quality of pasta made from soft wheat, reaction kinetics had to be measured at definite temperatures and water contents. It was chosen to realize such experiments in a pilot dryer. To be able to fix temperature and water content of product for a definite period of time, it was first necessary to determine sorption curves of pasta and a drying model including the values of apparent diffusivity of water at elevated temperatures.

This paper presents a method to meet these objectives. It consists in realizing a sequence of plateaux of air relative humidities of decreasing values, at constant temperature, in the dryer. Air-product equilibrium at the end of each plateau would have been too long to attain, therefore equilibrium product water content was calcultated using an exponential model. Apparent water diffusivity was determined by adjustement of a diffusive model, taking in account that the air humidity change from one plateau to the next one was a linear ramp and not a step-wise change.

The average relative repeatability of equilibrium water Content is 0.1% water/dry basis. There is more dispersion on apparent diffusivity.     

滦河水的除藻实验研究

该文针对滦河源水进行了杀藻的试验研究。研究结果表明：对引滦水而言,硫酸铜、高锰酸钾和过氧化氢三种杀藻剂的藻类去除率均随药剂投量的增加而升高;在原水含藻量较高（高于1000万个／L）情况下,硫酸铜较佳投量1．0mg／L,藻类去除率为70％～80％;过氧化氢投量4mg／L,藻类去除率为60％左右;高锰酸钾投量0．6mg/L,藻类去除率为85％;通过杀藻效果、经济性以及安全性等方面的综合比较,对于以有毒蓝藻为优势藻的引滦水,三种杀藻剂的优劣排序为：高锰酸钾〉硫酸铜〉过氧化氢。     

蔗糖快速简易分析法

<正> 小型甜菜糖厂都用碘量法测定蔗糖的含量。不受氨基酸与还原糖的影响,是此法的特殊优点。因此,所得结果比旋光仪或双旋光仪法准确。但由于操作手续冗长,大量耗用昂贵的碘化钾和碘,故此法在时间和费用上均不经济。次甲基兰容量法与碘量法相比,可缩短一半时间,使用一般药品,价格较低。但该法滴定终点有时不够明显,操作条件较严,重现性欠佳。用铁氰化钾容量法比较满意,时间和用药更为经济,滴定终点很明显,操作极简便,误差不大。现介绍如下:     

一种快速、准确的玻璃料方计算方法

采用微软公司Microsoft Excel的规划求解功能,可以快速准确地进行玻璃料方的计算,从而大大提高工作效率.本文以平板玻璃料方为例,对玻璃料方的电子计算机计算原理作介绍,并对利用Excel电子表格的规划求解功能进行玻璃料方计算的过程进行介绍.     

离子选择电极法测定水质氟化物

在水样中加入总离子强度调节缓冲溶液,由离子选择电极法测定标准溶液剂水样的电动势,由标准溶液的标准曲线求得水样的氟离子含量。     

一种简便廉价的谷胱甘肽测定法

报道了一种快速、简便和廉价的谷胱甘肽(GSH)含量测定的新方法。利用GSH的还原性将磷钼杂多酸还原成磷钼杂多蓝,在710 nm最大吸收波长处测其吸光度,吸光度与GSH的浓度在3.3×10-7-1.3×10-4mol·L-1范围内呈线性关系,相关系数r=0.9982,方法检测限为1.6×10-7mol·L-1,相对标准偏差RSD=1.1％(n=6),回收率为97.1％～103.5％。该法应用于药品中GSH含量的直接测定,结果满意。     

一种快速测定禽蛋中多种有机氯农药残留的方法

采用改良Qu ECh ERS法来提取禽蛋中的有机氯农药残留。样品经乙腈提取,用C18、NH2、石墨炭黑固体分散材料来净化,GC-ECD法检测。结果表明,该方法的检出限基本能达到GB/T 5009.19-2008和GB/T 5009.162-2008方法中要求的检出限。21种有机氯农药加标回收率均在80%~120%的范围内,RSD均小于10%,完全可以满足禽蛋中多种有机氯农药检测的要求。实验所用有机溶剂较少,也无须过GPC和SPE柱,可以为大批量的禽蛋类检测提供一种简单,快捷,准确,可靠,低成本的方法。     

A Highly Selective and Sensitive Chiral Derivatization Method for High- Performance Liquid Chromatographic Determination of the Stereoisomer Composition of Natural Products With Chiral Branched Alkyl Chains

In the study of chiral biologically active compounds such as pheromones, the analysis of the stereoisomer composition is essential to gain more insight into their stereochemical diversity, which affects the pheromone communication channels and therefore the diversification of species. This mini-review summarizes the development of fluorescence derivatization reagents for high-performance liquid chromatographic (HPLC) determination of the absolute configuration and stereoisomer composition of natural products with a chiral branched alkyl chain. The diastereomeric separation of anteiso fatty acids bearing a branched methyl group up to the C-26 position was achieved by reversed-phase HPLC under very low column temperature conditions using (1S,2S)-2-(2,3-anthracenedicarboximido)cyclohexanol as a derivatization reagent, enabling fluorescent detection of these compounds at femtomole levels. This method was also applicable to chiral alcohols and amines with chiral branched methyl groups using similar reagents containing a carboxyl group. These reagents were successfully applied to determine the absolute configurations and stereoisomer composition of the chiral alkyl chain of natural compounds including some insect pheromones, miyakosyne A, and plakoside A. The combination of these reagents and two-dimensional HPLC constitutes a very powerful tool for the analysis of the stereoisomers of natural crude samples. Furthermore, the analysis of some natural bioactive substances using this method demonstrated that natural substances are not always optically pure, consisting instead of stereoisomer mixtures exhibiting stronger activity than optically pure enantiomers. These results cast doubts on the concept of biological homochirality and demonstrate that natural pheromones do not always show the highest activity among all stereoisomers.