Oxidation of siloxanes during biogas combustion and nanotoxicity of Si-based particles released to the atmosphere

Siloxanes have been detected in the biogas produced at municipal solid waste landfills and wastewater treatment plants. When oxidized, siloxanes are converted to silicon oxides. The objectives of this study were to evaluate the transformation of siloxanes and potential nanotoxicity of Si-based particles released to the atmosphere from the gas engines which utilize biogas. Data available from nanotoxicity studies were used to assess the potential health risks associated with the inhalation exposure to Si-based nanoparticles. Silicon dioxide formed from siloxanes can range from 5 nm to about 100 nm in diameter depending on the combustion temperature and particle clustering characteristics. In general, silicon dioxide particles formed during from combustion process are typically 40–70 nm in diameter and can be described as fibrous dusts and as carcinogenic, mutagenic, astmagenic or reproductive toxic (CMAR) nanoparticles. Nanoparticles deposit in the upper respiratory system, conducting airways, and the alveoli. Size ranges between 5 and 50 nm show effective deposition in the alveoli where toxic effects are higher. In this study the quantities for the SiO₂ formed and release during combustion of biogas were estimated based on biogas utilization characteristics (gas compositions, temperature). The exposure to Si-based particles and potential effects in humans were analyzed in relation to their particle size, release rates and availability in the atmosphere. The analyses showed that about 54.5 and 73 kg/yr of SiO₂ can be released during combustion of biogas containing D4 and D5 at 14.1 mg/m³ (1 ppm) and 15.1 mg/m³ (1 ppm), respectively, per MW energy yield.     

SEDECAL移动式X射线摄影机的应用

目的：对移动式X射线摄影机在临床应用中出现的高压回路特殊故障案例进行判断、分析,以提供切实可靠的维修依据。方法：依据故障代码初步判断故障部位,采用分步排除法对其进行分析、判断,并确定故障的原因所在。结果：通过案例分析对该型号移动DR的高压逆变元件、驱动电路、波形判断及输出高压放电等问题有了进一步了解,便于对设备故障进行排除。结论：对X射线摄影系统高压电路特殊故障案例的分析及排除,尤其是对逆变电路的分析,使X射线摄影机出现高压过载时可及时采取相应的维修方法。     

多用低频脉冲磁场发生器的研制

本文介绍了我们研制的一种仪器－多用低频脉冲磁场发生器，仪器可输出磁感应强度幅值为０．１￣２Ｔ，周期为２Ｓ￣数ｍｉｎ的脉冲磁场。实验结果表明：该仪器可用于刺激人体外周神经，检测动作电位沿神经的传导速度；能改善人血的血液流变学指标。     

沼气发酵对病原菌杀灭效果的研究

目的探讨沼气发酵对病原菌的杀灭效果。方法建立中温(37℃)沼气发酵模型,并对4种常见病原体(金黄色葡萄球菌、乙型溶血性链球菌、伤寒沙门氏菌、福氏志贺菌)开展沼气发酵杀菌试验。结果金黄色葡萄球菌、乙型溶血性链球菌均在48小时时检测不出;伤寒沙门氏菌10天时检测不出;福氏志贺菌30天时仍能检出。结论沼气发酵对病原体有一定的杀灭效果,对革兰氏阳性菌的杀灭效果优于革兰氏阴性菌。     

Radiolabelling DOTA-peptides with 68Ga

Purpose A new field of interest is the application of ⁶⁸Ga-labelled DOTA-conjugated peptides for positron emission tomography (PET). The commercially available or house-made generators require time-consuming and tedious handling of the eluate. Radiolabelling at high specific activities without further purification is not possible, while high specific activities are necessary for peptides that potentially display pharmacological side-effects. Here we present the practical aspects and the results of radiolabelling DOTA-peptides with a TiO₂-based commercially available ⁶⁸Ge/⁶⁸Ga generator.Methods Reaction kinetics and parameters influencing the incorporation of the radionuclide at the highest achievable specific activity were investigated. Since high finger doses were anticipated during handling of the high beta-energy emitter ⁶⁸Ga, finger dosimetric measurements were performed during radiolabelling and in vivo administration.Results Fractionated elution of the generator revealed that 80% of the radioactivity was recovered in 1 ml. Bi- and trivalent ionic contaminants that compete for the incorporation of the radionuclide were below 50 nM; thus further tedious and time-consuming purification was avoided. Radiolabelling was performed at pH 3.5–4. Plastic shielding (7-mm wall thickness) around the syringe during administration effectively eliminated the positrons. In rats ⁶⁸GaCl₃ had slow clearance from blood, while ⁶⁸Ga-EDTA was rapidly cleared via the kidneys. Uptake of ⁶⁸Ga-DOTATOC in somatostatin receptor-positive tissues was high, with no significant difference between 1 and 4 h post injection.Conclusion DOTA-peptides for PET imaging can be labelled with ⁶⁸Ga up to specific activities of 1 GBq per nmol within 20 min, enabling the clinical application of peptides that display potential pharmacological side-effects.     

“Death may come on like a stroke of lightening ...”

Due to the decomposition of biological material, hydrogen sulphide (H₂S) is produced. In low concentrations, the well-known smell of “rotten eggs” is associated with H₂S. In higher concentrations, H₂S is an odourless and colourless gas that may cause rapid loss of consciousness, neurological and respiratory depression and imminent death—“... like a stroke of lightening”. Hydrogen sulphide poisoning is an un-common incident that is often associated with colleague fatalities. In this study, 4 fatal accidents with 10 deceased victims are reported and the morphological and phenomenological aspects are presented. In these cases, the morphological findings, namely, discolouration of the livores, pulmonary pathologies and sub-mucosal or sub-serosal congestion bleeding were found in nearly all cases. Also the impending threat for colleagues, first aid helpers and professional rescue teams is demonstrated. The suspicion of a fatal H₂S intoxication should be based on a precise scene analysis with respect to the possibility of life-threatening H₂S intoxication for the helpers, the typical scent of rotten eggs, which may be noted on the corpses and the abovementioned morphological findings. The diagnosis should be confirmed by a qualitative and, if possible, quantitative analysis of H₂S.     

应用沼气池液培养钝顶螺旋藻的初步探讨

应用广西农村推广的6m~3沼气池产生的废液为氮源,配合海盐,K_2HPO_4,FeSO_4,MnCl_2,NaHCO_3为培养基,在20m~2养藻池中培养螺旋藻成功,平均产量每天7.43g/m~2;经检验,藻体中8种人体必需氨基酸含量很高,每1000克干藻含粗蛋白601.2～634.5克。每生产1000克干藻成本13.3元,且发现这种培养液吸收大气中CO_2的能力很强,池中CO3~(2-)含量逐日上升,不再添加NaHCO_3,螺旋藻仍生长良好;这样可节约大量NaHCO_3,使成本降低。初步试验每1000克掺干藻20克饲料养罗非鱼(Tilapia Niloticas)可提高增重率14.1%。