Critical Insights in Laboratory Shear Wave Velocity Correlations of Clays

Shear wave velocity is an important mechanical/dynamic parameter allowing the characterization of a soil in the elastic range (γ < 0.001 %). Thirty five existing laboratory correlations of small strains shear modulus or shear wave velocity were examined in this study and are grouped into different general forms based on their geotechnical properties. A database of 11 eastern Canadian clay deposits was selected and used for the critical insights. The effect of the coefficient of earth pressure at rest was also examined. A range of variation for each general form of correlation was determined to take the plasticity index and void ratio values of investigated sites into account. The analysis shows a significant scatter in normalized shear wave velocity values predicted by existing correlations and raises questions on the applicability of these correlations, especially for eastern Canadian clays. New correlations are proposed for Champlain clays based on laboratory measurement of shear wave velocity using the piezoelectric ring actuator technique, P-RAT, incorporated in consolidation cells. An analysis of P-RAT results reveals the sample disturbance effect and suggests an approach to correct the effect of disturbance on laboratory shear wave velocity measurements. The applicability of the proposed correlations, including the disturbance correction, is validated by comparison with in situ measurements using multi-modal analysis of surface waves (MMASW).

Neurosteroid allopregnanolone (3α,5α-THP) inhibits inflammatory signals induced by activated MyD88-dependent toll-like receptors

We have shown that endogenous neurosteroids, including pregnenolone and 3α,5α-THP inhibit toll-like receptor 4 (TLR4) signal activation in mouse macrophages and the brain of alcohol-preferring (P) rat, which exhibits innate TLR4 signal activation. The current studies were designed to examine whether other activated TLR signals are similarly inhibited by 3α,5α-THP. We report that 3α,5α-THP inhibits selective agonist-mediated activation of TLR2 and TLR7, but not TLR3 signaling in the RAW246.7 macrophage cell line. The TLR4 and TLR7 signals are innately activated in the amygdala and NAc from P rat brains and inhibited by 3α,5α-THP. The TLR2 and TLR3 signals are not activated in P rat brain and they are not affected by 3α,5α-THP. Co-immunoprecipitation studies indicate that 3α,5α-THP inhibits the binding of MyD88 with TLR4 or TLR7 in P rat brain, but the levels of TLR4 co-precipitating with TRIF are not altered by 3α,5α-THP treatment. Collectively, the data indicate that 3α,5α-THP inhibits MyD88- but not TRIF-dependent TLR signal activation and the production of pro-inflammatory mediators through its ability to block TLR-MyD88 binding. These results have applicability to many conditions involving pro-inflammatory TLR activation of cytokines, chemokines, and interferons and support the use of 3α,5α-THP as a therapeutic for inflammatory disease.

Xây Dựng Văn Hóa Doanh Nghiệp - L.E.T. Solutions

Rất nhiều lãnh đạo đã mắc lỗi khi áp đặt văn hóa mà không khơi gợi nhận thức của nhân viên mình với các giá trị văn hóa.

Bí quyết khởi nghiệp từ con số 0

Rất nhiều, rất nhiều người nghĩ rằng khởi nghiệm là rất khó khăn, cần nhiều vốn và kiến thức… hay nhiều điều kiện tiền đề. Nhưng cũng có không ít người khởi nghiệm cũng đến rất tình cờ, dễ dàng như là duyên số.

Consolidation characteristics of hydraulically deposited tailings obtained from shear wave velocity (Vs) measurements in triaxial and oedometric cells with piezoelectric ring-actuator technique (P-RAT)

This paper presents the main results of a laboratory study of the use of shear wave velocity, Vs, to characterize hydraulically deposited tailings on the basis of density (void ratio), mean effective stress, and overconsolidation ratio. Tailings specimens from a gold mine in western Quebec were prepared in triaxial and oedometric cells in a manner that simulates hydraulic deposition. The specimens were consolidated isotropically and anisotropically (stress ratio, K of 0.38). Vs measurements were performed at each load increment using the piezoelectric ring-actuator technique (P-RAT). Correlations relating shear wave velocity to the void ratio, confining stress, and overconsolidation ratio of the tailings are presented. These laboratory correlations can be used for the characterization of the tailings by in situ Vs measurement. The application of these correlations to seismic cone penetration testing in an actual tailings impoundment is also presented.

Temporal Expression and Cellular Localization of PAPPA2 in the Developing Kidney of Rat

PAPPA2 is a metalloproteinase which cleaves insulin-like growth factor binding protein (IGFBP)-3 and IGFBP-5, and its role in pregnancy and postnatal growth is primarily studied. Using exclusion mapping, we reported a subcongenic (26-P) rat where a 0.71-Mbp region containing the pregnancy-associated plasma protein a2 ( Pappa2) allele of salt-insensitive Brown Norway (BN) was introgressed into Dahl saltsensitive (SS) genetic background, resulting in the reduction of salt sensitivity. Pappa2 was differentially expressed in the adult kidney of 26-P and SS rats. Here, the expression and cellular localization of Pappa2 in embryonic and postnatal kidneys of 26-P and SS rats were examined. Pappa2 mRNA expression was 5-fold higher in the embryonic kidney (day 20.5) of the 26-P rat compared with the SS rat. Pappa2 mRNA expression progressively increased with the development of kidney, reaching a peak at postnatal day 5 before trending downward in subsequent stages of development in both strains. At all tested time points, Pappa2 remained higher in the 26-P compared with the SS rat kidney. Immunohistochemistry studies localized PAPPA2 in the ureteric bud (UB) and distal part of S-shaped body. PAPPA2 was colocalized with IGFBP-5 in the UB and Na+/K+/2Cl− cotransporter–stained tubules, respectively. Future studies are needed to determine the role of Pappa2 in kidney development and mechanistic pathways involved in this process.

Rat bite fevers (Streptobacillus moniliformis and Spirillum minus infection)

Rat bite fever is usually attributable to Streptobacillus moniliformis in the Americas, Europe, and Australasia, and to Spirillum minus in Asia. Bites are increasingly common among children with pet rats, and pet shop and laboratory workers. Both bacteria are commensals of rats, some other rodents, and their predators. After an incubation period less than 1 week, S. moniliformis causes sudden high fever, rigors, myalgia, petechial rash, and migratory reactive or septic polyarthritis with synovial effusions. Complications can include fulminant septicaemia, endocarditis, pneumonia, and metastatic abscesses. S. minus infection (sodoku) has a longer incubation period with similarly high fever but concomitant exacerbation of the bite wound, local lymphadenopathy, papular rash, and arthralgia without effusions. In both diseases, fever subsides after a few days but may relapse repeatedly over months. Prevention is by controlling peri-domestic rats and avoiding bites by pet or laboratory rodents.