Temperature measurements during abrasive water jet osteotomy]

Working on bone is a major aspect of orthopaedic surgery. Despite its well-known appreciable thermal effects on the edges of the bone cut, the oscillating bone saw blade the oscillating saw remains the standard instrument both for cutting long bones and creating a bed for an endoprosthesis. The application of abrasive water jets offers the possibility of achieving an extremely precise curved cut in bone with no accompanying thermal effect. The thermographically measured absolute temperature increase at the cut edges seen with the water jet was 13 K maximum. The small process forces permit the application in automated handling systems.     

Germination responses to water potential in neotropical pioneers suggest large-seeded species take more risks

Background and Aims

In neotropical forests, very small-seeded pioneer species (<0·1 mg seed mass) recruit preferentially in small tree fall gaps and at gap edges, but large-seeded pioneers do not. Since water availability is related to gap size, these differences in microsite preference may reflect in part species-specific differences in germination at reduced water potentials.

Methods

For 14 neotropical pioneer species, the hypothesis is tested that small-seeded species, with shallow initial rooting depths, reduce the risks associated with desiccation by germinating more slowly and at higher water potentials than large-seeded species.

Key Results

Germination occurred both more quickly and at lower water potentials with increasing seed mass. For example, Ochroma pyramidale (seed mass 5·5 mg) had a time to 50 % germination (T₅₀) of 2·8 d and a median base potential for germination (ψ_b50) of −1·8 MPa while Clidemia quinquenervia (seed mass 0·017 mg) had a T₅₀ of 17·6 d and ψ_b50 of −1·1 MPa.

Conclusions

These data suggest that small-seeded species germinate only in comparatively moist microsites, such as small canopy gaps, which may reduce the risk of drought-induced mortality. Conversely, large-seeded species are able to germinate in the drier environment of large gaps, where they benefit by enhanced seedling growth in a high irradiance environment. The positive association of seed size and canopy gap size for optimal seedling establishment is maintained by differential germination responses to soil water availability coupled with the scaling of radicle growth rate and seed size, which collectively confer greater drought tolerance on large-seeded species.Key words: Germination, seed size, Panamá, neotropical, pioneer, water potential     

The pulsed water jet for selective removal of bone cement during revision arthroplasty]

Conventional tools used in prosthetic revision surgery have a limited range of action within the narrow cement mantle. Water jet cutting technology permits tiny and precisely controlled cuts, and may therefore be an alternative method of bone cement removal. Our study compares the cutting performance on bone cement (PMMA) and bone of a pulsed water jet and a continuous water jet. The aim of the study was to establish whether selective removal of PMMA is possible. 55 bone specimens (bovine femora) and 32 specimens of PMMA were cut with a continuous and a pulsed water jet at different pressures (40 MPa, 60 MPa) and pulse frequencies (0Hz, 50Hz, 250Hz). To ensure comparability of the results, the depths of cut were related to the hydraulic power of that part of the jet actually impinging on the material. While for PMMA the power-related depth of cut increased significantly with the pulse frequency, this did not apply to bone. The cuts produced in bone were sharp-edged. Since PMMA is more brittle than bone, the water jet caused cracks that enlarged further until particles of bone broke away. Although selective removal of PMMA without doing damage to the bone was not possible at the investigated settings of the jet parameters, the results do show that a pulsed water jet can cut bone cement much more effectively than bone. This is an important advantage over conventional non-selective tools for the removal of bone cement.     

Evaluation of petroleum-degrading potential of bacteria from water and sediment.

Bacteria from water and sediment of an oil-polluted harbor were examined for ability to degrade petroleum. Water samples contained a greater variety of bacterial species capable of degrading petroleum than sediment. Cultures from both water and sediment contained Pseudomonas and Acinetobacter spp. Bacteria present in the water samples produced significantly greater degradation of 2-,3-,4-, and 5-ring cycloalkanes and mono-, di-, tri-, tetra-, and pentaaromatics compared with bacteria in sediment samples.     

转基因作物潜在风险分析

转基因作物及其产品的发展非常快,它给人类带来巨大利益的同时,也可能产生一系列风险,着重分析转基因作物对生态环境和对人类健康两方面可能产生的潜在影响及其表现。     

Evaluation of synaptic potential dynamics from evoked impulse activity of neurons]

To evaluate intracellular potentials in the region of spike initiation of function lambda (t) is suggested which describes the dependence on time of the density of conditional probability of generation by the neuron of the first impulse in response to the stimulus. Qualitative correspondence of the dynamics of membrane potentials and function lambda (t) is demonstrated on the analog model. The application of the function lambda (t) to the classification of the neurons of auditory system is shown to be promising. The difference between the function lambda (t) and normalized poststimulus histogram allows to evaluate the refracteriness of the neuron.     

卫生填埋场微生物气溶胶的逸散及潜在风险

随着对微生物气溶胶认识的提高,其产生、来源、扩散及风险研究获得了越来越多的关注。卫生填埋场是微生物气溶胶的重要产生源之一。本文阐述了卫生填埋场气溶胶颗粒中微生物的浓度水平、粒径分布、种群结构,解析了微生物气溶胶的逸散特征及影响因素,介绍了微生物气溶胶对人体健康的潜在风险及评价方法,并展望了未来卫生填埋场逸散微生物的研究趋势及方向,为卫生填埋场微生物气溶胶的控制与削减提供了科学依据和参考。     

PGLA编织支架的制备与初步体内评价

目的:热拉伸会改变纤维的结构和性能,进而影响由纤维编织而成的支架的性能。本文考察了PGLA纤维的拉伸倍数对编织支架在SD大鼠皮下的体内降解行为的影响。方法:制备了基于生物可降解高分子材料聚乙交酯丙交酯(PGLA,GA/LA摩尔比=90/10)的完全生物可降解编织支架,通过测试支架在大鼠体内降解过程中的失重、表面形貌、热性能、径向压缩力等变化情况,考察了纤维的不同的拉伸倍数对支架体内降解过程的影响。结果:用拉伸倍数为5的PGLA纤维编织的支架在植入SD大鼠皮下后降解最慢,重量、吸水率、结晶度、化学成分和径向压缩力的变化最慢,植入体内10天后能够保持完整的支架形态。结论:纤维的拉伸倍数会影响由纤维编织成的支架的热性能和力学性能的变化,本研究结果表明这种新的手工编织的支架具有短暂支撑管腔狭窄的潜在应用,为支架的材料选择和制备方法提供了参考,为在体内起到短暂支撑作用的支架的深入研究提供了实验基础。     

Evaluation of disinfective potential of reactivated free chlorine in pooled tap water by electrolysis

Tap water is one of the causative factors of hospital infections. We examined the disinfective potential of electrolysis and mechanism of disinfection, and clarified the disinfective effect of electrolysis on tap water contaminated with bacteria, and discussed its clinical applications. Tap waters artificially contaminated with Pseudomonas aeruginosa, Escherichia coli, Legionella pneumophila, and Staphylococcus aureus could be sterilized by electrolysis at 20-30 mA for 5 min. A high-density suspension (10(6) CFU/ml) of a spore forming bacterium, Bacillus subtilis was not completely sterilized by electrolysis at 50 mA up to 30 min, but a low-density suspension (10(5) CFU/ml) was totally sterilized by electrolysis at 50 mA for 5 min. Electrolyzed P. aeruginosa changed morphologically, that is, there was bleb formation on the cell wall and irregular aggregation of cytoplasmic small granules. Moreover, cytoplasmic enzyme, nitrate reductase, was inactivated by the electrolysis. On the other hand, genomic DNA of the electrolyzed bacteria was not degenerated, therefore, their DNA polymerase activity was not completely inactivated. Consequently, the major agent in electrolysis for bactericidal action was considered to be free chlorine, and the possible bactericidal mechanism was by destruction of bacterial membranes, followed by the aggregation of peripheral cytoplasmic proteins. Electrolysis of tap water for both disinfecting contaminating bacteria and increasing the disinfectant capacity was considered effective with some limitations, particularly against high-density contamination by spore-forming bacteria. In clinical settings, electrolysis of tap water is considered effective to disinfect water for hand washing in operation theatres, and bathing water for immunocompromised hosts.     

Evaluation of health risks associated with trace metal exposure in water from the Barekese reservoir in Kumasi,Ghana

Abstract

Reservoirs play a pertinent role in providing potable water to humans and aquatic animals. Exposure to trace metal pollution in water may threaten aquatic ecosystem and human health. In this study, total and dissolved trace metals pollution and health risk they posed to humans in water sampled from the Barekese reservoir in Kumasi were investigated. Levels of Hg, As, Ni, and Cr in the water exceeded the WHO and USEPA stipulated limits. Arsenic and Cd recorded the highest non-carcinogenic health risk to humans. Hazard quotients (HQs) ?1 were recorded for an adult (HQ = 9.05) and a child (HQ = 21.11) via oral exposure to dissolved As in water samples. High HQ values of 40.10 and 17.20 for a child and an adult respectively were recorded through oral exposure for As. HQ of 1.41 was estimated for a child’s risk via dermal exposure to total Cd in water from the reservoir. Cancer risks of 1.63?×?10^?5 and 2.33?×?10^?6 were respectively recorded for a child and an adult oral exposure to dissolved As, suggesting possible adverse effects. The study concludes that anthropogenic activities within the Barekese catchment are deteriorating its water quality.     

Evaluation of the reproductive and developmental risks of caffeine

A risk analysis of in utero caffeine exposure is presented utilizing epidemiological studies and animal studies dealing with congenital malformation, pregnancy loss, and weight reduction. These effects are of interest to teratologists, because animal studies are useful in their evaluation. Many of the epidemiology studies did not evaluate the impact of the "pregnancy signal," which identifies healthy pregnancies and permits investigators to identify subjects with low pregnancy risks. The spontaneous abortion epidemiology studies were inconsistent and the majority did not consider the confounding introduced by not considering the pregnancy signal. The animal studies do not support the concept that caffeine is an abortafacient for the wide range of human caffeine exposures. Almost all the congenital malformation epidemiology studies were negative. Animal pharmacokinetic studies indicate that the teratogenic plasma level of caffeine has to reach or exceed 60 μg/ml, which is not attainable from ingesting large amounts of caffeine in foods and beverages. No epidemiological study described the "caffeine teratogenic syndrome." Six of the 17 recent epidemiology studies dealing with the risk of caffeine and fetal weight reduction were negative. Seven of the positive studies had growth reductions that were clinically insignificant and none of the studies cited the animal literature. Analysis of caffeine's reproductive toxicity considers reproducibility and plausibility of clinical, epidemiological, and animal data. Moderate or even high amounts of beverages and foods containing caffeine do not increase the risks of congenital malformations, miscarriage or growth retardation. Pharmacokinetic studies markedly improve the ability to perform the risk analyses.     

Aerobic biodegradation potential of subsurface microorganisms from a jet fuel-contaminated aquifer

In 1975, a leak of 83,000 gallons (314,189 liters) of jet fuel (JP-4) contaminated a shallow water-table aquifer near North Charleston, S.C. Laboratory experiments were conducted with contaminated sediments to assess the aerobic biodegradation potential of the in situ microbial community. Sediments were incubated with 14C-labeled organic compounds, and the evolution of 14CO2 was measured over time. Gas chromatographic analyses were used to monitor CO2 production and O2 consumption under aerobic conditions. Results indicated that the microbes from contaminated sediments remained active despite the potentially toxic effects of JP-4. 14CO2 was measured from [14C]glucose respiration in unamended and nitrate-amended samples after 1 day of incubation. Total [14C]glucose metabolism was greater in 1 mM nitrate-amended than in unamended samples because of increased cellular incorporation of 14C label. [14C]benzene and [14C]toluene were not significantly respired after 3 months of incubation. With the addition of 1 mM NO3, CO2 production measured by gas chromatographic analysis increased linearly during 2 months of incubation at a rate of 0.099 mumol g-1 (dry weight) day-1 while oxygen concentration decreased at a rate of 0.124 mumol g-1 (dry weight) day-1. With no added nitrate, CO2 production was not different from that in metabolically inhibited control vials. From the examination of selected components of JP-4, the n-alkane hexane appeared to be degraded as opposed to the branched alkanes of similar molecular weight. The results suggest that the in situ microbial community is active despite the JP-4 jet fuel contamination and that biodegradation may be compound specific.(ABSTRACT TRUNCATED AT 250 WORDS)     

噬菌体在食品安全中的应用和潜在风险

近年来,经食品传播的感染性疾病时有发生,有的国家甚至有增多趋势。噬菌体在早期被用来治疗细菌性疾病,现在人们已经意识到噬菌体在食品工业上的应用前景也非常广阔。已经有人提出把它作为食品添加剂使用以杀灭食源性致病菌。而噬菌体本身的特性也确实说明,噬菌体是保障食品安全的理想工具。因为噬菌体不仅安全可靠,而且有严格的宿主特异性,在杀灭食源性致病菌的同时不会杀死生产中的发酵菌株。噬菌体可以用在食品生产中的各个环节以杀灭或抑制病原菌,比如原料采集、生产、储藏等环节。探讨噬菌体杀灭食源性致病菌的应用前景和潜在风险。     

Cardiovascular effects of growth hormone treatment: potential risks and benefits

Growth hormone (GH) and insulin-like growth factor-I are involved in heart development and in maintaining cardiac structure and performance. Cardiovascular disease has been reported to reduce life expectancy both in GH deficiency (GHD) and in GH excess. Patients with GHD suffer from abnormalities of left ventricular performance, i.e. reduced diastolic filling and impaired response to peak exercise. Patients with GHD also have increased intima-media thickness at the common carotid arteries, associated with a higher occurrence of atherosclerotic plaques, which may further aggravate the haemodynamic conditions. This may contribute to increased cardiovascular and cerebrovascular risk. These cardiovascular abnormalities can be reversed, at least partially, with GH replacement therapy. In recent years, GH therapy has been used to increase cardiac mass in ischaemic or dilated cardiomyopathy, but the results have produced contradictory data.     

Value of waste water in agriculture. Evaluation of soil bacterial contamination, water table and plant culture]

The present study aim was to valorize the treated waste water as source of fertilizers for vegetables seed production and to assess the eventual bacteriological contamination risks of soil, plant and phreatic ground water table. The bacteriological analysis of drained water did not reveal any fecal coliforms vertical migration in depth and a low fecal contamination (thermotolerant coliforms) is limited to the levels of superficial horizons. The seed produced by using waste water showed a slightly fecal contamination which disappeared following treatment with a (5% chloride solution. The treated waste water improve the onion seeds production per hectare in spite of the increases of the phytopathogenic hazards.     

Biomedical applications and potential health risks of nanomaterials: molecular mechanisms

Nanotechnologies, defined as techniques aimed to conceive, characterize and produce material at the nanometer scale, represent a fully expanding domain, and one can predict without risk that production and utilization of nanomaterials will increase exponentially in the coming years. Applications of nanotechnologies are numerous, in constant development, and their potential use in the medical field as diagnosis and therapeutics tools is very attractive. The size particularity of these nanomaterials gives them novel properties, allowing them to adopt new comportments because of the laws of quantum physics that exist at this scale. However, worries are expressed regarding the exact properties that make these nanomaterials attractive, and questions are raised regarding their potential toxicity, their long-term secondary effects or their biodegradability, particularly when thinking of their use in the (nano)medical field. These questions are justified by the knowledge of the toxic effects of atmospheric pollution micrometric particles on health, and the fear to get an amplification of these effects because of the size of the materials blamed. In this paper, we first expose the sensed medical applications of nanomaterials, and the physicochemical and molecular determinants potentially responsible for nanomaterials biological effects. Finally, we present a synthesis of the actual knowledge regarding toxicological effects of nanomaterials. It is clear that, in regard to the almost empty field of what is known on the subject, there's an urge to better understand biological effects of nanomaterials, which will allow their safe use, in particular in the nanomedicine field.     

Relative water content and water potential of tissue 1

Relative water content (RWC) and water potential as measuredwith the pressure chamber were evaluated as indicators of waterstatus of tissue-cultured apple shoots and plantlets (shootswith roots). During the hydration required for RWC measurement,both water content and water potential exhibited the same hydrationkinetics, indicating that 10 h were required for full hydration.Once full hydration was reached, shoot mass remained relativelyconstant. Moisture release characteristics were also constructedand the associated shoot and plantlet water relations parameterswere estimated. Underin vitroconditions, both shoot and plantletwater potential were similar to the water potential of the culturemedium in which they were grown. The moisture release characteristicof shoots and plantlets was consistent with that expected fortypical plant tissues, and gave estimates of maximum modulusof elasticity (6.201.14 MPa), osmotic potential at saturation(–0.85 0.10 MPa), osmotic potential at zero turgor (–1.16 0.14 MPa) and RWC at zero turgor (78 2%) which were similarto values in the literature. Higher values of leaf conductanceand RWC were found in shoots and plantlets placed at 95% RH(21 C) compared to those at 90% RH. Plantlets had higher valuesof both conductance and RWC compared to shoots, suggesting thatinvitroroots are functional in water uptake. Relative water contentwas related to measures of physiological activity such as leafconductance, and it was also easier to measure than water potential.Relative water content is suggested as a sound index of waterstatus in tissue culture plants. Key words: Conductance, microculture, water status, water stress.     

Enteric viruses of humans and animals in aquatic environments: health risks, detection, and potential water quality assessment tools.

Waterborne enteric viruses threaten both human and animal health. These pathogens are host specific and cause a wide range of diseases and symptoms in humans or other animals. While considerable research has documented the risk of enteric viruses to human health from contact with contaminated water, the current bacterial indicator-based methods for evaluation of water quality are often ineffectual proxies for pathogenic viruses. Additionally, relatively little work has specifically investigated the risk of waterborne viruses to animal health, and this risk currently is not addressed by routine water quality assessments. Nonetheless, because of their host specificity, enteric viruses can fulfill a unique role both for assessing health risks and as measures of contamination source in a watershed, yet the use of animal, as well as human, host-specific viruses in determining sources of fecal pollution has received little attention. With improved molecular detection assays, viruses from key host groups can be targeted directly using PCR amplification or hybridization with a high level of sensitivity and specificity. A multispecies viral analysis would provide needed information for controlling pollution by source, determining human health risks based on assessments of human virus loading and exposure, and determining potential risks to production animal health and could indicate the potential for the presence of other zoonotic pathogens. While there is a need to better understand the prevalence and environmental distribution of nonhuman enteric viruses, the development of improved methods for specific and sensitive detection will facilitate the use of these microbes for library-independent source tracking and water quality assessment tools.     

Application of a water jet system to the pretreatment of cellulose

Plant cellulose is the most abundant organic compound on earth. Technologies for producing cellulose fiber or improving the enzymatic saccharification of cellulose hold the key to biomass applications. A technology for atomizing biomass without strong acid catalysis remains to be developed. The water jet is a well-known device used in machines (e.g., washing machines, cutters, and mills) that use high-pressure water. In this study, we examined whether a water jet system could be used to atomize crystalline cellulose, which comprises approximately 50% of plant biomass. The Star Burst System manufactured by Sugino Machine Limited (Sugino Machine; Toyama, Japan) is a unique atomization machine that uses a water jet to atomize materials and thereby places lower stress on the environment. After treatment with this system, the crystalline cellulose was converted into a gel-like form. High-angular annular dark-field scanning transmission electron microscopy showed that the cellulose fibers had been converted from a solid crystalline into a matrix of cellulose nanofibers. In addition, our results show that this system can improve the saccharification efficiency of cellulases by more than three-fold. Hence, the Star Burst System provides a new and mild pretreatment system for processing biomass materials.