直接拉伸试验及Superpave规范系统研究蜡对沥青低温性能的影响

用两种不同分子量的石蜡及一种微晶蜡掺和在沥青中,来研究蜡的性能(如分子量分布、平均分子量等)对沥青低温性能的影响.用Superpave沥青胶结料性能规范系统的BBR、DTT、临界龟裂温度(Tcritical)及玻璃转换温度(Tg)来研究掺有3%或6%蜡的沥青低温性能,低分子量及分子量分布窄的石蜡降低了沥青的DTT破坏应力,同时增加了正割模量(Secant Modulus)及BBR的热应力.微晶蜡对沥青的DTT破坏应力的影响比较少,并且不影响正割模量,但增加了BBR的热应力;但当将不同蜡的沥青混合,即将蜡的分子量分布扩大,则DTT破坏应力略为降低,正割模量不变,而BBR的热应力则减少.换言之,如果将含不同蜡的沥青混合,则蜡对沥青低温性能的影响降低,这会改善含蜡沥青的低温性能,原因可能是蜡的凝结受其分子量所影响,较宽的分子量分布会导致蜡在较宽的温度范围内慢慢凝结,缓和了蜡突然结晶对沥青低温性能的有害反应.     

Hemostatic risk factors of coronary artery disease in the Chinese

Induction of the mitochondrial permeability transition in vitro is well-characterized and widely implicated in the mechanism of oxidant-induced cell death. Despite an abundance of in vitro evidence, implication of mitochondrial dysfunction in the mechanism of chemical toxicity in vivo awaits demonstration of the induction of the mitochondrial permeability transition in tissues from intoxicated animals. Menadione (2-methyl-1,4-naphthoquinone), an agent known to induce the permeability transition in isolated liver mitochondrial in vitro, was administered as a single bolus to adult male rats, and hepatic mitochondria were isolated 24 h later. Mitochondria from menadione-treated rats exhibited an increased sensitivity to calcium-induced inhibition of state 3 respiration and loss of respiratory control, as well as a greater sensitivity to calcium-induced calcium release that was inhibited by cyclosporine A. Associated with this was the depolarization of membrane potential and swelling of mitochondria from menadione-treated animals, but not control animals. Both the calcium-dependent depolarization and swelling of mitochondria from menadione-treated rats were inhibited by adding either cyclosporine A or ruthenium red. The results are consistent with the induction of the mitochondrial permeability transition and provide the first evidence for the manifestation of an increased sensitivity to this response as a result of chemical exposure in vivo.     

Fabrication of a highly bendable LCD with an elastomer substrate by using a replica‐molding method

Abstract— A highly bendable liquid‐crystal display was fabricated by using a multi‐functional elastomer substrate of self‐aligning LC molecules without any surface treatment. One of the two substrates is a plastic substrate while the other is a multi‐functional elastomer substrate produced by a replica‐molding technique. The multi‐functional elastomer substrate has pixel‐encapsulating walls that serve as spacers and provide mechanical stability and reproducibility against bending deformations. The highly bendable LCD demonstrates great flexibility, durability, and excellent electro‐optic performances in a highly bent state.     

TEM studies of strain-induced martensitic formation in fatigued Fe-18Mn alloy

Austenitic Fe-18Mn alloy was cyclically deformed at various total strain amplitudes. The structural changes induced by cyclic straining in Fe-18Mn alloy were investigated by transmission electron microscopy. At a low strain amplitude of 0.4%, the formation ofε-martensite associated with deformation twins and stacking faults was observed in this alloy. As the applied strain amplitude was increased to 1.0%,α′-martensite embryos were induced in the alloy investigated. These embryos coalesce into a lath structure upon subsequent cyclic deformation.     

Attachment loss with postmenopausal age and smoking

To determine whether postmenopausal bone loss and factors associated with osteoporosis affect tooth retention, we examined vertebral and proximal femoral (postcranial) bone mineral density in relation to tooth loss and attachment loss in a cross-sectional study of 135 postmenopausal women (age range 41-70 yr). Women had at least 10 teeth and no evidence of moderate or severe periodontal disease. Full-mouth attachment loss measurements were made using a pressure-sensitive probe, and bone density was determined by dual-energy X-ray absorptiometry. Attachment loss was correlated with tooth loss (number of remaining teeth, radiologically determined), but not with vertebral or proximal femur bone density. Multivariate analysis showed current smoking (p = 0.01), years since menopause (p = 0.02) and the interaction of age and current smoking (p < 0.01), to be statistically significant predictors of attachment loss in our study population.     

Twenty-four-hour pharmacokinetics of rectal acetaminophen in children: an old drug with new recommendations

Oxidized low density lipoprotein (LDL) and acetyl LDL are recognized by the scavenger receptor class A type I/II (SR-AI/II) on macrophages and liver endothelial cells. Several investigators have suggested that there are additional receptors specific for oxidized LDL, but characterization of these alternate receptors for oxidized LDL and evaluation of their quantitative importance in uptake of oxidized LDL has been difficult because of overlapping ligand specificity with SR-AI/II. The purpose of this study was to determine the importance of SR-AI/II in the removal of modified LDL from the bloodstream in vivo. The clearance rate of oxidized LDL from plasma in normal mice was very rapid, and > 90% of injected dose was removed from the blood within 5 min. Clearance rates of oxidized LDL were equally high in SR-AI/II knockout mice, indicating that this receptor is not required for removal of oxidized LDL from plasma. Surprisingly, there was no difference in the clearance rate of acetyl LDL in wild-type and SR-AI/II knockout animals. The plasma clearance of radioiodinated acetyl LDL was almost fully blocked by a 50-fold excess of unlabeled acetyl LDL, but the latter only inhibited oxidized LDL clearance by approximately 5%. Both modified LDLs were cleared mostly by the liver, and there was no difference in the tissue distribution of modified LDL in control and knockout mice. Studies in isolated nonparenchymal liver cells showed that Kupffer cells accounted for most of the uptake of oxidized LDL. Extensively oxidized LDL and LDL modified by exposure to fatty acid peroxidation products were efficient competitors for the uptake of labeled oxidized LDL by SR-AI/II-deficient Kupffer cells, while acetyl LDL and malondialdehyde-modified LDL were relatively poor competitors.     

Optical backplane system using waveguide-embedded PCBs and optical slots

As discussed in this paper, a practical optical backplane system was demonstrated, using a waveguide-embedded optical backplane board, processing boards, and optical slots for board-to-board interconnection. A metal optical bench was used as a packaging die for the optical devices and the integrated circuit chips in both the transmitter and the receiver processing boards. The polymer waveguide was produced by means of a hot-embossing technique and was then embedded following a conventional lamination processes. The average propagation loss of these waveguides was approximately 0.1 dB/cm at 850 nm. The dimension and optical properties of the waveguide in an optical backplane board were unchanged after lamination. As connection components between transmitter/receiver processing boards and an optical backplane board, optical slots were used for easy and repeatable insertion and extraction of the boards with a micrometer-scale precision. A 1/spl times/4 850-nm vertical-cavity surface-emitting laser array was used with 2 dBm of output power for the transmitter and a p-i-n photodiode array for the receiver. This paper successfully demonstrates 8 Gb/s of data transmission between the transmitter processing board and the optical backplane board.