Laboratory limits

Attention deficit hyperactivity disorder (ADHD) is not a disease. The symptoms of its three dimensions (activity, attention and impulsivity) are normally distributed in the population, with an arbitrary level of symptoms being designated pathological. The presence of the ADHD cluster is never grounds for any positive diagnosis; it is an indication for further assessment. Positive response to stimulants is not specific to the ADHD population, and is no way diagnostic.     

高硅含锗物料中锗的提取工艺探讨

通过生产试验，总结出从高硅含锗物料中提取锗的生产工艺方法，使提锗的回收率由30%-60%提高到92%以上。     

原子发射光谱仪对机械装置用润滑油监测概述

主要论述原子发射光谱仪在机械系统用润滑油中的应用、原理及发展过程.并结合案例说明了原子发射光谱对机械设备用润滑油监测的必要性.     

Fragmentation of phosphopeptides in an ion trap mass spectrometer

A systematic study of the fragmentation pattern of phosphopeptides in an electrospray (ESI) ion trap mass spectrometer is presented. We show that phosphotyrosine- and phosphothreonine-containing peptides show complicated fragmentation patterns. These phosphopeptides were observed to lose the phosphate moiety in the form of H3PO4 and/or HPO3, but were also detected with no loss of the phosphate group. The tendency to lose the phosphate moiety depends strongly on the charge state. Thus, the highest observed charge state tends to retain the phosphate moiety with extensive fragmentation along the peptide backbone. We also show that phosphoserine-containing peptides have relatively simple fragmentation patterns of losing H3PO4. This loss is independent of the charge state. We suggest strategies for the accurate identification of phosphorylation sites using the ion trap mass spectrometer.     

Metal Recovery from Bottom Ash of an Incineration Plant: Laboratory Reactor Tests

The bottom ashes, produced by the industrial incinerators, are an essential secondary raw material resource that has been drawing attention to recover economically important metals. In the present study, a hydrometallurgical process (chemical leaching) has been discussed to recover some economically important metals using lab scale reactors (600 mL and 2L capacity). Prior to the leaching tests, the material was characterized for chemical composition and mineralogical phase analysis through XRD. In addition, the conventional process of magnetic separation was applied before leaching tests to remove some easily separable parts. Two acidic reagents (HCl and H₂SO₄) and an alkali reagent (NaOH) have been used to compare the recovery of metal values from the pre-treated bottom ash samples at varying concentrations. Process parameters such as acid/alkali concentration, working volume and temperature have been optimized and the recoveries of metal values under optimum conditions were recorded. The studies showed that 3M H₂SO_4, 1.5 L working volume and 80°C were sufficient to leach 88% Mo, 82% V, 37% Ni, 37% Fe, and 28% Cu. Acid leaching tests using H₂SO₄ were found to be an economical and appropriate solvent for metal recovery from bottom ash.     

锗在冶金分析中几个问题的探讨

锗的治金物料种类较多,可大致分为三类：含锗原料、湿法或火法冶金中间产物以及锗粗级产品。与含锗量对应被文泛采用的分析方法也有3种：痕量锗(＜0.001%)采用萃取-笨芴酮水相光度法[1-3];微量锗(＜0.2%)采用蒸馏-苯芴酮水相光度法[4];高含量锗(＞0.2%)采碘酸钾滴定法[5-7].     

Recovery of germanium and other valuable metals from zinc plant residues

The main purpose of this study was to characterize and to extract germanium from the copper cake of Çinkur Zinc Plant. The physical, chemical and mineralogical characterization of the ground copper cake sample obtained from Çinkur showed that it was 84% below 147 μm containing 700 ppm germanium. The copper cake also contained 15.33% Cu, 15.63% Zn, 1.66% Cd, 1.33% Ni, 0.64% Co, 0.35% Fe, 2.62% Pb, 12.6% As, 0.18% Sb and 3.42% SiO₂. The mineralogical analysis indicated the complex nature of the copper cake which was mainly composed of metallic and oxidized phases containing copper, arsenic, zinc, cadmium, etc. The sulfuric acid leaching experiments were performed under the laboratory conditions. The optimum collective extraction of germanium and other valuable metals was obtained at a temperature range 60 to 85 °C for a leaching duration of 1 h with sulfuric acid concentration of 150 gpl and using a solid–liquid ratio 1/8 g/cc. Under these conditions, the recovery of germanium was 92.7% while the other metals were leached almost completely. The optimum selective leaching conditions of germanium was determined as half an hour leach duration, 1/8 g/cc solid–liquid ratio, 100 gpl sulfuric acid concentration and a temperature range 40 to 60 °C. Under these conditions the leach recovery of germanium was 78%. The dissolution's of other metals like cobalt, nickel, iron, copper, cadmium and arsenic were almost low. So, germanium would be separated more selectively at the following precipitation by tannin stage.     

Multifrequency two-dimensional Fourier transform ESR: an X/Ku-band spectrometer

It has long been accepted that the response of T cells to a protein antigen is strongly influenced by parameters governing processing and presentation of the immunodominant epitopes. Recent evidence has suggested, however, that subtle changes in the nature of the ligand itself may also affect the outcome of T-cell receptor (TCR) ligation, necessitating a re-evaluation of previously accepted paradigms of T-cell activation. In particular, activation may no longer be regarded as an all-or-nothing event, but appears to involve both quantitative and qualitative dimensions. This revolution in our understanding has emanated from the recent discovery that analogues of immunogenic peptides, so-called altered peptide ligands (APLs), may elicit a subset of normal activation events, or profoundly influence responses to the wild-type epitope. As such, the potential offered by APLs for modifying the outcome of deleterious immune responses involved in autoimmunity has not passed unnoticed. Indeed, the design and exploitation of novel reagents based on the structure of autoantigenic epitopes has enjoyed some measure of success in the treatment of experimental models of autoimmune disease and holds promise for their exploitation within the clinical arena.     

Procedures for tandem mass spectrometry on an ion trap storage/reflectron time-of-flight mass spectrometer

In this work, we demonstrate tandem mass spectrometry on an ion trap storage-reflectron time-of-flight mass spectrometer (IT/reTOFMS). Ion isolation and activation were achieved by resonant excitation using multi- and single-frequency waveforms generated from an analog circuit. Product-ion spectra of small polypeptides are obtained, which are comparable in fragmentation to those acquired on sector or hybrid mass spectrometers. Several important parameters governing the tandem mass spectrometry process, including the activation tickle voltage, type of collision gas, activation period and cooling period after the fragmentation were optimized using leucine-enkephalin as a model. Although the limited energy deposition from collisional activation in our experiments does not allow efficient fragmentation of large singly charged polypeptides with m/z higher than 1000, the problem may be partially solved by taking advantage of fragmenting the multiply charged ions produced from the electrospray ionization source as demonstrated for a synthetic polypeptide of molecular weight 2782. Compared to the singly charged form, the reduced m/z of multiply charged forms experience a greater trapping force as described by the pseudopotential well-depth model. Increased pseudopotential well-depths for multiply charged species permit the use of greater fragmentation energy at lower RF potentials. These conditions facilitate the fragmentation of large polypeptides, yet are suitable for trapping singly charged fragments. These experiments indicate that the high efficiency associated with ion dissociation and fragment-ion collection in the trap and the storage capability for detection of ions using the non-scanning mode of the IT/ reTOF analyzer may provide an alternative means for acquiring sequence-specific information of polypeptides at low picomol levels of sensitivity.