Understanding how brass ball valves passing certification testing can cause elevated lead in water when installed

The lead leaching potential of new brass plumbing devices has come under scrutiny as a significant source of lead in drinking water (>300 μg/L) of new buildings around the world. Experiments were conducted using ball valves that were sold as certified and known to have caused problems in practice, in order to better understand how installed products could create such problems, even if they passed “leaching tests” such as National Sanitation Foundation (NSF) Standard 61 Section 8. Diffusion of lead from within the device into water when installed can increase lead leaching by orders of magnitude relative to results of NSF testing, which once only required exposure of very small volumes of water within the device. “Normalization” of the lead-in-water result tended to produce estimates of lead concentration that were much lower than actual lead measured at the tap. Finally, the presence of flux could also dramatically increase lead leaching, whereas high water velocity had relatively little effect.     

Profile and secondary flow losses in a high-lift LPT blade cascade at different reynolds numbers under steady and unsteady inflow conditions

The aerodynamic flow field downstream of a Low-Pressure High-Lift(HL)turbine cascade has been experimentally investigated for different Reynolds numbers under both steady and unsteady inflows,in order to analyse the cascade performance under real engine operating conditions.The Reynolds number has been varied in the range 100000相似文献   

A 120-dB Dynamic Range CMOS Image Sensor With Programmable Power Responsivity

A high dynamic range CMOS image sensor providing a user-programmable power responsivity curve is presented. Each pixel integrates, besides a 4T active pixel structure, a voltage comparator and an analog memory to implement a time-to-saturation scheme while also providing the standard integrated photo-current signal. The sensor generates two 10-bit analog outputs allowing a typical dynamic range exceeding 120 dB with a temporal noise lower than 0.13% and a fixed pattern noise of 0.4% (1.7%) of the total signal swing (2 V) at low (high) irradiance without any external calibration procedures. A 140 times 140-pixel array has been fabricated in a 0.35-mum, two-poly four-metal (2P4M), 3.3-V standard CMOS technology. The chip measures 3.9 times 4.6 mm² with a pixel pitch of 15 mum and a fill factor of 20%.     

The influence of nimodipine and MK-801 on the brain free arachidonic acid level and the learning ability in hypoxia-exposed rats

1. The influence of voltage dependent calcium channel blocker (VDCC), nimodipine and N-methyl-D-aspartate (NMDA) receptor antagonist, MK-801 on the brain free arachidonic acid (FAA) level and on the learning ability in hypoxia-exposed rats was examined. 2. Some animals were decapitated after cerebral hypoxia had been obtained and the brain FAA level was determined by gas chromatography. The other animals were trained in a passive avoidance procedure and were exposed to hypoxic conditions immediately after the learning trial response had been acquired. A passive avoidance retention test was performed 24 hours later. 3. Various doses of nimodipine (0.03; 0.1; 0.3 and 1.0 mg/kg) and MK-801 (0.03; 0.1 and 0.3 mg/kg) had been injected 30 minutes before biochemical or behavioral procedures started. 4. It was found that hypoxia strongly increased the brain FAA level and impaired the retention of the passive avoidance response. 5. Pretreatment with 0.3 mg/kg and 1.0 mg/kg of nimodipine prevented the brain FAA accumulation. It has also been shown that all tested doses of nimodipine significantly improved the retention deficit in the animals exposed to hypoxia. 6. Neither the one of tested doses of MK-801 influenced significantly the increase of the brain FAA level and/or passive avoidance behavior in hypoxic animals. 7. These results confirm the hypothesis that the brain FAA accumulation and cognitive impairment, caused by hypoxia, are maybe associated with disturbances in calcium homeostasis and that nimodipine may be useful in ameliorating the hypoxia-induced brain tissue damage. Blocade of NMDA receptor-channel complex by MK-801 was not sufficient to prevent hypoxia-induced neuronal damage.     

Pyrazole-related nucleosides. 4. Synthesis and antitumor activity of some 1-tetrahydropyranyl-4-substituted pyrazoles

Continuing our studies on the structure-activity relationships of some pyrazole nucleosides (1a-h) structurally related to ribavirin, tiazofurin and selenazofurin, we describe here the synthesis and antitumor/antiviral/antimicrobial activity of a new series of 1-tetrahydropyranyl-4-substituted pyrazoles. In this study, the tetrahydropyranyl moiety (THP), designed as a mimic of the glycosidic portion of the parent compounds 1a-h, has led to a few derivatives with moderate cytotoxic activity against leukemia/lymphoma and solid tumor-derived cell lines (IC50 14-100 microM). The compounds obtained through substitution of the ribofuranosyl moiety by the THP moiety were still active, the free heterocyclic bases were devoid of any activity.     

Discussion on application of the Weibull distribution to electrical breakdown of insulating materials

The Weibull distribution is commonly used for statistical processing of breakdown data of electrical insulation. The statistical theory of breakdown that has been proposed since the 1970s has introduced a two-variables Weibull distribution in order to take into account both the stress applied and the failure times. In this paper this distribution is thoroughly discussed and then rejected. Indeed, the random variable is only one; the other is an independent variable that becomes random only through the first, with the same shape parameter. The case of breakdown after electrical or multiple-stress aging (electric strength test on aged specimens) is also examined and the probability distribution function is written even in the general case, where the probability is a function of several variables. Only one of the latter, i.e. the electric strength ES, is the random variable while the others, such as the applied stresses and the time at which the ES measurement is performed, are independent     

Sex trading and psychological distress among women on methadone.

This study examined the relationship between sex trading and psychological distress among a nonrandom sample of women recruited from 3 methadone maintenance clinics in New York City. Face-to-face interviews with 280 women (M age?=?40.7) revealed that 32% had traded sex for money or drugs in the previous year. Compared to other participants, these women reported less education and higher rates of incarceration in the past year, sexually transmitted diseases, childhood sexual abuse, partner abuse, and current regular crack/cocaine and alcohol use. Hierarchical multiple regression analysis indicated that sex traders scored 0.41 units higher than non-sex traders on the General Severity Index of the Brief Symptom Inventory after controlling for all relevant covariates. The findings emphasize the need to consider the interrelation of psychological distress, abuse, and addiction in designing public health interventions addressing methadone maintained women. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Abuse, health locus of control, and perceived health among HIV-positive women.

This study of 230 predominantly poor Hispanic and African American women aged 25 to 61 years living with HIV/AIDS in New York City revealed high levels of both sexual (39%) and physical (44%) trauma before the age of 16. Both types of early trauma were correlated with later trauma, and all forms of trauma were significantly associated with current perceived health. In multivariate analyses controlling for relevant covariates, the Powerful Others and Internal Control subscales of the Multidimensional Health Locus of Control Scales (K. A. Wallston, B. S. Wallston, & R. DeVellis, 1978) acted as independent predictors of perceived health rather than (as hypothesized) mediators of the association between trauma and perceived health. Findings underscore the importance of addressing trauma and perceptions of control over one's physical health in the provision of health services to HIV-positive women. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Large program implementation on minicomputers

A method is decribed to fit a very large program (usually executed on very big mainframes, like a CDC 7600 or IBM 370/168) on a 16-bit minicomputer with memory management support. The method outlined is fully general, even if references are made to a specific example: the implementation of the CERN program HYDRA on a PDP 11/70.