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1.
The containers of mineral water and the foreign plastic substances which were found in the mineral water were investigated. Most of plastic bottles were made of polyethylene terephthalate (PET) and the caps were made of polypropylene (PP), polyethylene (PE) or aluminum. PE liners were attached to some caps. Most of the foreign plastic substances were PET while others were PE, PP, Teflon and rubber. Some bottles had a scratch on the top inside. The origin of most PET fragments was presumed to be scraped off the bottles by the lowering of the injection nozzle during the water filling process. The sources of the other substances were also determined.  相似文献   

2.
1. It was shown that special apparatus for cleaning milkbottles makes additional desinfection unnecessary with regard to bacteriological and hygienic aspects. -- 2. Milk-bottles should be processed centrally for safety reasons. Special basket-containers facilitate a more economic washing process, transport and storage of the bottles. -- 3. Physiologically optimal milk formulas, as available today, should be prepared and filled into bottles in the ward where they are needed, immediately before use, to guarantee bacteriologically optimal conditions. -- 4. With appropriate organization within a clinic it should be possible to store special dietary formulas which have been prepared centrally, not in the wards, over the required time without the risk of bacterial contamination. The need for regular and systemic bacteriological checks is emphasized.  相似文献   

3.
The Edward C Little Water Recycling Facility (ECLWRF) is the largest high-purity water recycling facility in the United States. Here, microfiltration (MF) membranes play a critical role in treating the secondary effluent and serving as pretreatment to the downstream reverse osmosis systems. New chemical clean-in-place (CIP) formulations were evaluated through pilot-scale tests for their ability to improve the performance restoration for the Phase III continuous MF (CMF) membranes at the ECLWRF. Membrane autopsies found that the primary fouling mechanisms for the CMF membranes were biological and organic in origin. It was also determined that the current CIP protocol provided an incomplete removal of the biological and organic foulants. The cleaning test results found that the current CIP regime for the Phase III system performed better than the four commercially available cleaning solutions evaluated here. However, improved results were obtained when hydrogen peroxide was added to the current CIP regime consisting of caustic soda and the commercially available Memclean C cleaning solution. The effects of the addition of hydrogen peroxide to the standard cleaning procedure shows some promise; however, further research is needed to understand the cleaning mechanisms and long-term effects of using hydrogen peroxide as a cleaning additive.  相似文献   

4.
In this paper,the online measurement of the alkalinity of caustic washing liquid by the conductivity method was discussed,and a working curve of the conductivity vs.alkalinity was established,for which the correlation coefficient is 0.9979 (n=7 ).The influence of the temperature of the caustic washing liquid and the presence of coexisting ions,such as iron and oil,on the accuracy of the conductivity method was discussed.The temperature is compensated for by establishing the correlation between conductivity and temperature.When the iron concentration is≤1000 mg/L,and the oil concentration is ≤1000 mg/L,the deviation in the results obtained using the conductivity and titration methods is≤2.5 g/L.The t-test results show that there is no systematic devia-tion between the conductivity and titration methods.The conductivity method has the advantages of a fast response and good real-time performance,which meet the requirements for the online determination of the alkalinity of caustic washing liquid.  相似文献   

5.
The surface structural properties of biofouled membranes from a laboratory-scale submerged anaerobic membrane bioreactor (SAnMBR) treating kraft pulping evaporator condensate after cleaning were studied. A flat sheet polyvinylidene fluoride (PVDF) membrane was used for the study. Three different cleaning methods, physical cleaning (PC), maintenance chemical cleaning (MCC), and recovery cleaning (RC) were applied to the fouled membrane surface, and the treated membranes were subject to flux recovery and surface structural analysis by using spectroscopic methods, zeta potential measurement, attenuated total reflectance-Fourier transform infra red spectroscopy (ATR-FTIR), and advanced correlative microscopic methods, including confocal laser scanning microscopy (CLSM), atomic force microscopy (AFM), and scanning electron microscopy (SEM). Neither PC, MCC, nor RC methods restored the membrane permeability to initial conditions. Adhesion of a thin extracellular polymeric substance (EPS) layer, consisting of proteins and polysaccharides with a thicknesses of 4.0?μm, 5.3?μm, and 7.1?μm and roughness of 190?nm, 236?nm, and 273?nm was observed on RC, MCC, and PC treated membrane surfaces, respectively. Partial flux recovery was achieved with the MCC and RC methods. This was correlated to the reduction of the protein associated with the foulant. Polysaccharides were found to be the most stable and predominant EPS constituent in relation to protein on the biofouled layer of RC and MCC membrane surfaces.  相似文献   

6.
Pure Sn coatings are prepared by pulse current (PC) electrodeposition using aqueous acidic sulfate plating bath. The effects of various electroplating parameters such as current density, additive concentration, duty cycle, frequency, pH, bath temperature, and stirring rate (bath rotation) on the evolution of surface morphology of the coatings have been studied. The as-deposited coatings are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and surface profilometry. It is found that the current density, additive concentration, duty cycle, frequency, and pH have a major influence while temperature and stirring rate of the bath have a minor effect on the grain-size distribution. The mechanism involved in the morphology evolution and grain-size distribution due to the varying electroplating parameters has also been discussed.  相似文献   

7.
Mother's milk is the best food for the baby. The need to use foods other than mother's milk has always represented a challenging problem to be solved. The author warns that the high mortality during the first year of life during the early years of the XXth century (20%) peaked at an amazing 80% in children artificially fed at orphanages. In the considered years, the usage of baby's bottle spread among babies that could not be fed by mothers or wet-nurses. The idea of rubber teat 1845 and of automatic devices for the production of glass bottle - 1903 - contributed to the diffusion of the baby's bottle. First baby's bottles were variously shaped. However, the finding of severe gastroenteritis caused by a long rubber tube attached to the rubber teat (the so-called death-bottle), together with the necessity of a careful cleaning and the diffusion of Soxhket's system (sterilization of many bottles in the same container) will lead to the choice of large mouthed cylindrical bottles, very similar to the plastic bottles used nowadays.  相似文献   

8.
Previous research has indicated that residential washing machines are potential sources of pollution due to the associated use of chemicals found in consumer products, for example, ethanol in laundry detergent and chlorine in bleach. Washing machines may also emit hazardous air pollutants found in contaminated drinking water. To better understand the extent and impact of chemical emissions from tap water, 26 experiments were completed using a residential washing machine and a cocktail of chemical tracers representing a wide range of physicochemical properties. Variable operating conditions for these experiments included water temperature, amount of clothes present in the machine, water volume, and level of washwater agitation. Chemical stripping efficiencies and mass transfer coefficients were determined during each cycle (fill, wash, and rinse) of a normal washing machine event. Headspace ventilation rates were determined using an isobutylene tracer gas. Mass transfer rates were significantly influenced by operating parameters as exhibited by a wide range of chemical stripping efficiencies. Stripping efficiencies ranged from 0.74 to 36% for acetone, 8.2 to 99% for toluene, 10 to 99% for ethylbenzene, and 6.9 to 100% for cyclohexane.  相似文献   

9.
研究了1,2-辛二醇对铝酸钠溶液种分过程的影响。结果表明,1,2-辛二醇对铝酸钠溶液种分过程产生抑制作用。1,2-辛二醇的添加浓度、实验温度以及苛碱浓度等因素对1,2-辛二醇改善铝酸钠溶液种分效果具有显著影响。添加浓度小于1.25 mmol/L时,1,2-辛二醇对铝酸钠溶液的抑制程度很小,产品氢氧化铝的粒度分布基本维持与未添加时一致;添加浓度超过1.5 mmol/L,抑制作用非常明显,产品氢氧化铝粒度曲线主峰明显左移,平均粒度减小。温度越低,苛碱浓度越大,1,2-辛二醇对铝酸钠溶液分解抑制作用越大,产品氢氧化铝的细化程度越大。X射线衍射(XRD)显示,加入1,2-辛二醇后种分产品的晶型不变。  相似文献   

10.
采用耗散粒子动力学模拟方法(DPD)研究了聚丙烯酸(PAA)与聚乙二醇(PEG)复配添加剂在硅酸二钙表面的吸附性能。为了合理地表征聚合物与硅酸二钙表面的相互作用,聚合物与表面的相互作用通过匹配分子动力学(MD)计算得到的过剩吸附量与DPD计算得到的过剩吸附量来确定,从而实现介观与微观尺度之间的耦合。研究结果表明,PAA5:PEG5复配添加剂吸附效果、驱替水分子的能力以及自身吸附稳定性皆强于单一添加剂PAA、PEG。在PAA5:PEG5复配添加剂在吸附过程中,聚合物PAA与PEG之间存在着协同作用,使其抑制硅酸二钙分解的效果较优。   相似文献   

11.
With an aim to recycle waste polymers as a carbon resource in steelmaking, in‐depth investigations have been carried out on polymer/coke blends and molten steel at 1823 K. Three polymers, namely high density polyethylene (HDPE), polyethylene terephthalate (PET), and bakelite were blended with metallurgical coke and devolatilized at 1473 K using a drop tube furnace. High temperature interactions of various chars with molten steel were investigated at 1823 K using the sessile drop technique in argon atmosphere; the influence of polymers on the interfacial phenomena and carbon dissolution was determined. While the residual volatiles from HDPE did not affect the chemical composition of interfacial products, the coverage of the interfacial region was somewhat slower than metallurgical coke. Oxygen present in PET was found to oxidize liquid steel leading to the formation of FeO at the interface modifying both the chemical composition and the morphology of the interfacial region. CaCO3, present as a filler impurity in bakelite was found to act as a fluxing agent and lowered the melting point of the ash layer at the metal/carbon interface. The addition of polymers improved the overall carbon dissolution into molten steel by a small extent as compared to metallurgical coke. This study has shown that a variety of waste polymers can be utilized to partially replace metallurgical coke in steelmaking.  相似文献   

12.
The biocompatibility of a 3 mm band made of polyethylene terephthalate (Trevira hochfest) has been tested in an experimental study within right knee joints of 60 sheep. After transsecting the anterior cruciate ligament (ACL), two randomized groups were formed. In group I, the ACL was repaired according to the Marshall technique whilst in group II an additional 3 mm polyethylene terephthalate (PET) augmentation band was implanted using the through-the-condyle (TTC) procedure. To assess the biocompatibility of the augmentation device the knee joints of both groups were punctured and the synovial fluids were analyzed before, as well as 2, 6, 16, 26, and 52 weeks after the operation. In addition, the histologic appearance of excised suprapatellar pouches and ipsilateral inguinal and popliteal lymphatic noduli were examined. Comparing both groups no significant differences were found neither before nor after the augmented and non-augmented ACL repair. No pathological increase in the total protein concentration occurred after operation and no significant differences versus the preoperative analysis were found. No synovitis signalling a decrease in the glucose concentration was observed. The cytological examination revealed no increase of the leukocyte cell count results. Within the synovial specimen neither free nor phagocytosed PET wearparticles could be detected. In groups I and II the histological appearance of excised popliteal and inguinal lymphatic noduli showed a normal result. In 25% of the PET augmented ACL repairs, a slight concentration of PET wearparticles and solitary, multinuclear giant foreign body cells could be seen in the histological preparations of suprapatellar pouches.  相似文献   

13.
A field method is described, which allows the qualitative estimation of pesticide contamination in the edge-of-field runoff. The method employs cheap and easy-to-use runoff sampling bottles, which were installed in an agricultural stream catchment over a period of three growing seasons. During this time 18 runoff events were detected, in nine of which insecticide contamination was measured (maximum concentrations: lindane 0.7 microgram l-1 and 12.7 micrograms kg-1, parathion 20 micrograms l-1 and 728 micrograms kg-1, fenvalerate 18.4 micrograms l-1 and 924 micrograms kg-1). These insecticides were detected mainly as particle-bound chemicals. On about 80% of the occasions the presence or absence of runoff measured in the field was in agreement with a simulation of runoff presence or absence using the runoff model KINEROS.  相似文献   

14.
The transition of the superficial microstmcture of freshwater pearls induced by Ce was investigated by means of scanning electron microscopy. The pearls were cultured in freshwater containing 0 (control group ), 0.5, 1, and 1.5 mg·L^-1 of a Ce additive. X-ray photoelectron spectroscopy (XPS) measurement showed that the concentration of Ce absorbed in the superficial microstmcture of pearls was positively correlated to the additive Ce. At the same time, the surface microstmcture of pearls changed greatly with Ce concentration, the shape of the blocks changed from spindly to perfect regular hexagonal sheets and finally to round discs. The glossiness of the pearls changed correspondingly with the microstmcture, pearls possessing the regular hexagonal blocks having the highest glossiness. Therefore, the REE Ce exerted a significant influence on the microstructure and glossiness of freshwater pearls. An appropriate quantity of Ce may improve the glossiness of pearls.  相似文献   

15.
 采用热重分析法(TGA)研究了城市固体垃圾中的4种常见废弃塑料——废弃聚乙烯农膜(PE)、废弃聚苯乙烯泡沫塑料(PS)、废弃聚丙烯编织袋(PP)、丢弃的聚对苯二甲酸乙二醇酯饮料瓶(PET)和高炉喷吹用煤粉的热解特性,并计算出它们各自的热解动力学参数。结果表明:废塑料和煤粉的热裂解都属于一级反应,但是煤粉裂解温度远高于废塑料,而裂解量却远小于废塑料,在高炉高温条件下,废塑料将具有比煤粉更好的燃烧特性。  相似文献   

16.
Bacterial contamination of hydrophilic contact lens solutions may play an important role in contact lens-associated ocular infections. This study investigated bacterial contamination in 52 different hydrophilic contact lens solutions marketed in Spain by 12 different companies. We filtered the entire contents of 5 new, factory-sealed bottles from each of the 52 brands and cultured the fitter on a neutralizing broth plate. Bacteria were cultured, isolated, and identified from 29 of the 260 bottles tested (11.15%). Eight of the 52 brands had at least 1 of the 5 bottles contaminated (15.38%). Contaminated solutions originated from four different companies. One manufacturer contributed most of the positive cases due, presumably, to an industrial contamination by Pseudomonas fluorescens. The rest of the culture-positive bottles were contaminated by Bacillus spp. and Oerskovia spp.  相似文献   

17.
BACKGROUND: Caustic ingestion is frequent in children, sometimes leading to esophageal stricture. PATIENTS AND METHODS: Between 1988 and 1994, esogastroscopy was performed in 65 children after caustic ingestion. The children were classified in three groups: no lesion (group A), minimal lesions (group B) and severe lesions (group C). Nature of the caustic substance, clinical signs and evolution were compared in the three groups. RESULTS: Median age was 2 years for the 65 children (24 girls, 41 boys). Ingestion occurred at home (94%) during meal periods. Substances were dishwater detergents (n = 14), oven cleaner (n = 10), bleach (n = 9), washing powder (n = 4), others (n = 20), more often in a liquid form (n = 37) than solid (n = 28). Children had no symptoms (57%), presented emesis (n = 20) or abdominal pain (n = 10) not correlated to endoscopic findings, and hematemesis (n = 3) or respiratory distress (n = 4), both symptoms seen only in group C. Buccal lesions (41%) were not correlated to endoscopic findings. After endoscopy, 28 children (43%) were classified into group A and 20 children (31%) in group B. Among the 17 children (26%) of the group C, eight developed an esophageal stricture: seven long strictures requiring replacement of the esophagus, one short stricture requiring repeated dilations. CONCLUSION: Esophageal stricture is still a severe complication after caustic ingestion. These data stress the interest of controlled studies to confirm the preventive role of high dose corticosteroids, and the importance of the prevention of accidental caustic ingestions in children.  相似文献   

18.
The effects of the operating conditions, the initial concentrations of marine diesel fuel (MDF) and the coexisting Pb in the soil, and the ethylene diamine tetra acetic salt (EDTA) in solution on MDF removal by sodium dodecyl sulfate (SDS) washing were extensively investigated with the aim of optimizing the process parameters and determining the MDF removal efficiency by SDS under different contamination conditions. The experimental results from batch tests indicated that the majority of MDF was removed by SDS in the first 2?h, and its optimal pH was nearly neutral. Increasing the SDS concentration linearly increased the MDF removal efficiency. At a given SDS concentration, the removal efficiency was dependent on the existing forms of MDF in soils, and the free phase of MDF was found to be more easily removed than the adsorbed phase. MDF removal by SDS was significantly reduced by the coexisting Pb in soils, which likely forms a complexation with SDS and thereby enhances the partitioning of MDF in the soil by the re-adsorption of released MDF onto the hydrophobic tails of the adsorbed SDS. EDTA alone, or with SDS, could remove MDF, but the remaining MDF in the contaminated soil after EDTA washing became more difficult to be removed by SDS. Therefore, the EDTA washing followed by SDS washing is not recommended for MDF removal.  相似文献   

19.
Plastics have become the widely used materials because of their advantages, such as cheapness, endurance, lightness, and hygiene. However, they occur as solid waste masses within a short time when used in package industry. This causes waste and soil pollution, because they do not decompose. Polyethylene terephthalate (PET) and high-density polyethylene (HDPE) are the most important varieties of plastics that are usually used in the manufacturing drinking water bottles. Depending on their surface characteristics, these plastics can be separated from each other by flotation method. But, all plastics are naturally hydrophobic. In order to employ flotation for the separation process, one of these plastics is made hydrophilic, while the other remains hydrophobic. Plasticizer reagents are used to change the plastics' surface character and make them hydrophilic. The aim of this investigation is to research selective flotation of used PET and HDPE by utilizing Triton XL-100N and Diethylene Glycol Dibenzoate-type plasticizers at optimum temperature, pH, and conditioning time. As a result of this investigation, PET–HDPE concentrates having about 100% purities were obtained with 100% recovery, when the mixture of PET–HDPE was conditioned for 30 min with 40 kg/t NaOH at pH 10 and 1000 g/t Dietilen Glycol Dibenzoate at 50°C.  相似文献   

20.
Pharmaceutical agents and irrigating solutions are widely used in both optometric and ophthalmologic practices. Contamination of these containers or solutions could possibly pose some risk of infection to a patient. We set out to investigate the possible contamination of a representative sample of these containers in small office practices. Representative bottles of two diagnostic pharmaceutical agents and an irrigating solution were obtained from primary care optometric and ophthalmologic practices in the San Francisco-Oakland Bay area. These bottles were tested to investigate the rate of contamination and to identify the types of microorganisms in the contaminated solutions. Sixty total samples (proparacaine, tropicamide, and an irrigating solution) were randomly cultured, and 11.7% of the samples showed contamination. Pseudomonas cepacia, Staphylococcus epidermidis, Pseudomonas putida, and Streptococcus species were the predominant organisms isolated from the contaminated bottles. In addition, 17 of the original 60 containers were further cultured for investigation of the dried residue particles around the threads of the containers. Of these 17 containers, 13 (76.5%) tested positive for Staphylococcus and Micrococcus species.  相似文献   

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