An X-ray Radiography Study of the Effect of Thermal Cycling on Damage Evolution in Large-Area Sn-3.5Ag Solder Joints

There is a need for next-generation, high-performance power electronic packages and systems utilizing wide-band-gap devices to operate at high temperatures in automotive and electricity transmission applications. Sn-3.5Ag solder is a candidate for use in such packages with potential maximum operating temperatures of about 200°C. However, there is a need to understand the thermal cycling reliability of Sn-3.5Ag solders subject to such high-temperature operating conditions. The results of a study on the damage evolution occurring in large-area Sn-3.5Ag solder joints between silicon dies and direct bonded copper substrates with Au/Ni-P metallization subject to thermal cycling between 200°C and 5°C are presented in this paper. Interface structure evolution and damage accumulation were followed using high-resolution X-ray radiography, cross-sectional optical and scanning electron microscopies, and X-ray microanalysis in these joints for up to 3000 thermal cycles. Optical and scanning electron microscopy results showed that the stresses introduced by the thermal cycling result in cracking and delamination at the copper–intermetallic compound interface. X-ray microanalysis showed that stresses due to thermal cycling resulted in physical cracking and breakdown of the Ni-P barrier layer, facilitating Cu-Sn interdiffusion. This interdiffusion resulted in the formation of Cu-Sn intermetallic compounds underneath the Ni-P layer, subsequently leading to delamination between the Ni-rich layer and Cu-Sn intermetallic compounds.     

Effect of C/S ratio on morphology and structure of hydrothermally synthesized calcium silicate hydrate

The samples of the C-S-H series were synthesized by hydrothermal reaction of fumed silica, CaO and deionized water at initial C/S ratios between 1.0–1.7. Phase composition and structural and morphology characteristics of C-S-H samples were analyzed by XRD, IR and SEM. The experimental results showed that the d-spacing of (002), (110) and (020) decreased, the d-spacing of (200) increased, and the d-spacing of (310) varied randomly, the polymerization of silica tetrahedra of C-S-H decreased, and morphology of C-S-H samples varied from sheet shapes to long reticular fibers as C/S ratio increased.     

The effect of prepartum injection of vitamin E on health in transition dairy cows

The objective of this study was to investigate parenteral vitamin E for the prevention of peripartum disease in dairy cows. A randomized clinical trial was conducted in 21 commercial dairy herds. Cows (n = 1142) were randomly assigned to receive either a single subcutaneous injection of 3000 IU of vitamin E, or placebo, 1 wk before expected calving. Serum alpha-tocopherol was significantly increased in treated cows at 7 and 14 d, but not at 21 d after injection. Overall, there were no significant differences between treatment groups in the incidence of retained placenta, clinical mastitis, metritis, endometritis, ketosis, displaced abomasum, or lameness. However, there was a conditional benefit of treatment for reduction of the incidence of retained placenta. Cows with marginal pretreatment vitamin E status (serum alpha-tocopherol to cholesterol mass ratio < 2.5 x 10(-3)) that received an injection of vitamin E tended to have reduced risk of retained placenta. However, in cows with adequate serum vitamin E, there was no reduction in the incidence of any disease. For clinical application, primiparous animals were most likely to benefit from prepartum injection of vitamin E.     

Serum and urine metal levels in patients with metal-on-metal surface arthroplasty

The resurgence of metal-on-metal articulating surfaces for hip arthroplasty has also heightened concerns about the degree and magnitude of metal particle generation and the accompanying increase in circulating metal ion concentrations. In this study, we measured the concentration of chromium in serum and urine and the concentration of cobalt in serum in twenty-five patients with modern metal-on-metal surface arthroplasty of the hip in a prospective manner. The results showed that the mean post-operative chromium in serum levels were 22-fold, 23-fold and 21-fold higher at 3, 6 and 12 months post-operative, respectively, than pre-operative levels. The mean post-operative cobalt in serum levels were 8-fold, 7-fold and 6-fold higher at 3, 6 and 12 months post-operative, respectively, than pre-operative levels. The mean post-operative chromium in urine levels were 9-fold, 10-fold and 14-fold higher at 3, 6 and 12 months post-operative, respectively, than pre-operative levels. The values seen in this study with the current generation of surface arthroplasties are: (a) lower than those seen in an earlier generation of surface arthroplasties; (b) in the same range as those observed in association with metal-on-metal conventional total hip replacements, which typically have smaller head sizes; (c) higher than values observed in patients with conventional metal-on-polyethylene articulating couples.     

Understanding attitudes toward affirmative action programs in employment: Summary and meta-analysis of 35 years of research.

Affirmative action programs (AAPs) are controversial employment policies in the United States and elsewhere. A large body of evidence about attitudinal reactions to AAPs in employment has accumulated over 35 years: at least 126 independent samples involving 29,000 people. However, findings are not firmly established or integrated. In the current article, the authors summarize and meta-analytically estimate relationships of AAP attitudes with (a) structural features of such programs, (b) perceiver demographic and psychological characteristics, (c) interactions of structural features with perceiver characteristics, and (d) presentation of AAP details to perceivers, including justification of the AAP. Results are generally consistent with predictions derived from self-interest considerations, organizational justice theory, and racism theories. They also suggest practical ways in which AAPs might be designed and communicated to employees to reduce attitudinal resistance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intravenous cocaine discrimination in humans.

Ten cocaine-dependent participants were trained to discriminate between intravenous saline and 20 mg/70 kg cocaine. During the first session, saline and cocaine injections were alternated twice, with each separated by 1 hr. The injections were identified by letter codes. During the next 3 sessions, 12 trials were conducted, with saline and cocaine administered 6 times each in pseudorandom order. Thirty minutes following each injection, participants were asked to identify the injection by letter code. Seven of the 10 learned the discrimination (at least 10 trials correct). To evaluate sensitivity, the investigators tested participants with different doses of cocaine in test sessions. In the next phase, methamphetamine (5 and 10 mg/70 kg) and pentobarbital (50 and 100 mg/70 kg) were given intravenously during test sessions to determine whether the discrimination exhibited pharmacological class selectivity. During the evaluation of sensitivity and selectivity, training sessions were interspersed. As dose of cocaine increased, the number of participants identifying the test dose as cocaine increased, demonstrating sensitivity. The higher doses of methamphetamine and pentobarbital substituted for cocaine. The physiological and subjective effects of cocaine and methamphetamine were stimulant-like and dose related. Pentobarbital produced no physiological changes but increased Visual Analog Scale ratings of Sedation, Good Drug Effect, and High. This failure to demonstrate pharmacological selectivity may be related to participants' learning a drug-vs.-no-drug discrimination, and thus it may be necessary to alter training procedures in future studies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Analytic validation of an infrared milk urea assay and effects of sample acquisition factors on milk urea results

The objective of this study was to determine if milk samples, as they are routinely collected by Ontario Dairy Herd Improvement, would yield accurate milk urea results with an infrared assay. This investigation involved analytic validation of the infrared assay and assessment of the effect of DHI routine sample acquisition factors on milk urea results. Analytic validation of an automated milk urea assay was performed by assessing the relative accuracy and precision of milk urea results produced by the Fossomatic 4000 Milk Analyzer, an infrared method of analysis, compared with the Eurochem test, an accepted reference method. Results indicated that, when interpreted at the group level, milk urea results between the infrared method and the reference test were in good agreement. The two tests shared a similar and high level of precision. Milk urea concentrations obtained from composite (metered) milk samples, and not quarter stripping samples, were most representative of concurrent serum urea concentrations. The addition of bronopol preservative did not result in a numerically important change in milk urea concentrations. Storage of preserved metered milk samples for up to 4 d at either room temperature or by refrigeration, or for up to 3 d by freezing, did not result in changes in milk urea concentrations. We concluded that milk samples, as they are routinely collected and handled by DHI, are suitable for measurement of milk urea concentrations with the infrared method of analysis if data are interpreted at the group level.     

Reply to Mahrer.

Replies to Mahrer's response (see record 2007-09057-001) to the current author's book review (see record 2007-09053-001). Mahrer raises some important questions and submits that different approaches differ significantly in the categories they use to make sense of what clients do, and that each has its own way of eliciting, listening to and observing what the client says and does. I agree that approaches differ on these features and believe that what we listen for and how we make sense of what we hear is the most fundamental aspect of any therapeutic approach. In fact training in an approach involves not only learning the intervention skills of the approach, which is the easy part, but learning when and how to use the intervention, which is based on listening and process diagnosis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ontario bulk milk somatic cell count reduction program: progress and outlook

The objective of this study was to describe the results of the ongoing somatic cell count (SCC) reduction program in Ontario, Canada and to provide an outlook regarding the possible scenarios beyond the final stages of the current reduction program. The data were from all of the approximately 9500 farms in the province of Ontario during the last 10 yr and included monthly data for kilograms of milk sold, mean milk component measurements, and milk quality measurements (bulk milk SCC, plate loop count, and inhibitor presence). Four of five steps in the control program had a significant impact on the mean monthly bulk milk SCC. The total decrease in mean SCC that was attributable to the program was approximately 80 x 10(3) cells/ml. The monthly occurrence of inhibitor violations increased significantly. Cross-classification of the annual mean bulk milk SCC and the incidence of inhibitor violations indicated that the incidence specifically increased for farms with a relatively high bulk milk SCC. In 1994, bulk milk SCC increased, primarily because of farms that had a mean bulk milk SCC between 150 x 10(3) and 450 x 10(3)/ml. The small relative contribution of farms with higher bulk milk SCC was due to their relatively low production and the small number of farms in those classes. The Ontario SCC reduction program was initially successful in the reduction of mean bulk milk SCC. Further reduction will require the active participation of farms with a relatively low bulk milk SCC. Not only is it necessary to penalize farms that exceed thresholds, but also an incentive to prevent farms with good udder health management from increasing bulk milk SCC is of great importance. The increase in inhibitor violations is of concern and requires further attention.