Skeletal resistance to the calcemic action of parathyroid hormone in uremia: role of 1,25 (OH)2 D3

Studies were carried out to investigate the role of 1,25(OH)2D3 in the skeletal resistance to the calcemic action of parathyroid hormone. The change in serum calcium after the intravenous infusion of 2 U of parathyroid extract (PTE)/kg body wt/hr for eight hours was evaluated in thyroparathyroidectomized (T-PTX) dogs before, and one, two and three days after, induction of uremia by bilateral ureteral ligation (11 dogs) or by bilateral nephrectomy (8 dogs). In another six nephrectomized and T-PTX dogs, 0.68 ug of 1, 25 (OH)2D3/day was given on the day of nephrectomy and for two days thereafter. Serum creatinine in each day of the study was not different among the three groups. The study also included the evaluation of the effect of sham operation (five dogs) and the administration of 1,25 (OH)2D3 to dogs with normal renal function (four dogs) on the calcemic response to PTE, as well as the reproducibility of such a response in the same animal. The results showed that 1) the calcemic response to PTE was markedly impaired after one day of bilateral ureteral ligation or nephrectomy, but the impairment was more severe after nephrectomy; 2) the calcemic response to PTE after two or three days of bilateral ureteral ligation was similar to that seen at one day after nephrectomy; 3) 1, 25 (OH)2D3 partially restored the calcemic response to PTE in the nephrectomized animals to levels similar to those seen after one day of bilateral ureteral ligation; 4) sham operation did not affect the response to PTE, and repeated infusion of PTE produced similar changes in the concentrations of serum calcium. The data indicate that (a) a deficiency of 1,25 (OH)2D3 is at least partly responsible for the skeletal resistance to the calcemic action of PTH in uremia; (b) uremia, per se, may also contribute to this phenomenon; and (c) the kidney after one day of complete bilateral ureteral ligation may still produce 1,25 (OH)2D3, but this ability is compromised after two days of ureteral obstruction.     

Communicative incompetence and the non-fluent bilingual.

Examined the evaluative reactions during a communication experiment with 32 male native speakers of English who had moderate but nonfluent speaking abilities in French. Ss had to speak to interlocutors in either English or French using either a casual or formal speech register. Results show that Ss evaluated their interlocutor less favorably when using their second language if the sociolinguistic demands of the communication situation required the use of a casual rather than a formal speech register. The reverse pattern was observed when Ss used their native language. Results are discussed in terms of self-perception theory and a communicative competence approach to 1st and 2nd language learning. (15 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Thermomechcmical processing of Inconel 718 by shock-wave deformation

The response of Inconel 718 nickel-base alloy to thermomechanical processing (TMP) utilizing a 510 Kbar planar shock wave was evaluated. The results were compared with those of conventional TMP by cold rolling to 19.1 pct reduction in thickness; this provided a generalized (or effective) strain equivalent to the transient shock strain. Instead of deformation in the solution treated condition, the inclusion of a predeformation, partial aging step in an optimized TMP schedule led to the greatest improvements in strength, stress-rupture life, and low-cycle fatigue life. The mechanical behavior was correlated with substructure and microstructure. Predeformation aging inhibits thermal recovery during final aging and produces a uniform dispersion of γ′’ precipitates. On a generalized (or effective) strain basis, conventional TMP by cold rolling produces higher strengths than shock TMP due to a higher dislocation density in the former. This suggests that maximum shear strain is a better basis of comparison. Since dislocation substructure is the primary contributor to property modification of Inconel 718 by TMP, the effective service temperature of thermomechanically processed material is limited to 1200°F (649°C), irrespective of the method of working.     

The potential of volatile organic compound analysis in cervicovaginal mucus to predict estrus and ovulation in estrus-synchronized heifers

Cervicovaginal mucus is a mixture of mucins, ions, salts, and water, the proportions of which change during the reproductive cycle. It is suspected that this mucus emits an important volatile signal indicative of the reproductive state of the female. The objective of this study was to identify volatile organic compounds (VOC) in bovine cervicovaginal mucus that are modulated during the estrous cycle and could potentially be used as biomarkers of estrus and ovulation. Cervicovaginal mucus was collected from crossbred beef heifers (n = 8), which were synchronized using an 8-d controlled internal drug release (CIDR) protocol and in which onset of estrus and time of ovulation were determined by visual observation and ultrasonography, respectively. Mucus samples were collected between 0 and 96 h after CIDR removal (estrus onset occurred at 49.1 ± 3.3 h after CIDR removal). A validation study was performed on an independent group of 15 heifers from which cervicovaginal mucus samples were collected every 8 h from 40 to 80 h after CIDR removal. The VOC in mucus were identified using gas chromatography-mass spectrometry and selected compounds were quantified using selected-ion flow-tube mass spectrometry. The presence of 47 VOC was detected in mucus samples by gas chromatography-mass spectrometry with those exhibiting highest abundance including 2-butanone, acetone, 2-pentanone, 4-methyl-2-pentanone, 1-(1-methylethoxy)-2-propanone, ethanol, 2-methyl-2-propanol, and 2-butanol. All VOC peaked between 24 to 47 h after the onset of estrus (ovulation occurred 26.6 ± 5.6 h after estrus onset). Two VOC, 2-pentanone and 4-methyl-2-pentanone, exhibited a significant increase at the onset of estrus, whereas concentration of 2-butanone increased significantly just after estrus onset, indicating that these VOC may be used as putative biomarkers of estrus. The results of our study may contribute to the development of a sensor device based on VOC to aid the detection of estrus and ovulation in cattle, with particular relevance for the dairy industry where the majority of females are bred by artificial insemination.     

合成纤维和玻璃纤维制成的Ashrae过滤介质的性能比较

对常用的超细玻璃纤维制成的Ashrae袋式过滤介质、标准驻极熔喷聚丙烯Ashrae袋式过滤介质和一种新型的熔喷聚丙烯细纤维Ashrae袋式过滤介质进行了比较。标准玻璃纤维毡所用的纤维非常微细,密实性(固体体积分数)很低,导致α值(品质因子)较高,但该材料不能吸附静电荷。标准熔喷聚丙烯过滤介质所用的纤维比玻璃纤维粗得多,密实性也更高,因能吸附很多静电荷,其初始α值比玻璃纤维毡要大得多,但放电后的α值却比玻璃纤维毡低得多。新型的熔喷聚丙烯细纤维过滤介质可完全驻极,其初始α值和标准熔喷聚丙烯过滤介质一样高,但由于更加细微的纤维结构,在放电后所保持的α值更高。     

Products of pertechnetate radiolysis in highly alkaline solution: structure of TcO2 x xH2O

The chemistry of technetium in certain high-level nuclear waste (HLW) tanks at the Hanford Site complicates the treatment and vitrification of HLW. A major problem is the presence, in certain tanks, of unidentified, lower-valent technetium species, which are difficult to remove from the waste by current separation processes. Radiolytic reduction of TcO4- in alkaline solutions containing selected organic compounds, approximating the conditions in HLW, was investigated to determine the classes of compounds that can be formed under these conditions. Insoluble TcO2 x xH2O is the primary radiolysis product with the majority of organic compounds investigated, including citrate, dibutyl phosphate, and aminopolycarboxylates. X-ray absorption fine structure (XAFS) measurements show that TcO2 x xH2O has a one-dimensional chain structure consisting of edge-sharing TcO6 octahedra with bridging oxide and trans water ligands. When diols, such as ethylene glycol, are present, only soluble, Tc(IV) alkoxide compounds are produced. The XAFS and UV-visible spectra of these compounds provide evidence for a binuclear structure similar to (H2EDTA)2Tc2(mu-O)2. The properties of the Tc(IV) alkoxide complexes were determined and are consistent with those observed for the soluble, lower-valent technetium complexes that complicate the treatment of HLW at the Hanford site.     

Physical properties of burnt timber, with special focus on the drying performance

Burnt wood has been found to perform different from sound (green) wood when dried together, but also with regards to other physical and mechanical properties. In this study the drying performance of wood burnt to different degrees in recent plantation fires was investigated, and the physical, chemical and wood anatomical properties of these different wood types were determined. Different cell structure and chemical composition due to thermal degradation could be observed as well as different drying performance and variation in mechanical properties. An explanation for the deviant drying performance was attempted with the observed structural changes.     

Nonlinear dynamic analysis of curved beams

A computational procedure is presented for predicting the dynamic response of curved beams with geometric nonlinearities. A mixed formulation is used with the fundamental unknowns consisting of stress resultants, generalized displacements and velocity components. The governing semidiscrete finite element equations consist of a mixed system of algebraic and differential equations. The temporal integration of the differential equations is performed by using an explicit half-station central difference method. A procedure is outlined for lumping both the flexibilities and masses of the mixed model, thereby uncoupling all the equations of the system. The advantages of the proposed computational procedure over explicit methods used with the displacement formulation are discussed. The effectiveness and versatility of the proposed approach are demonstrated by means of numerical examples.