Brittle solids, such as rock or concrete, may contain numerous randomly distributed micro-flaws (e.g. cracks, pores or weak inclusions). When they are loaded in compression, cracks may nucleate from ...these flaws. These cracks then continue to grow in a stable manner with the increasing axial compression, curving toward an orientation parallel to the direction of axial compression. Their propagation and interaction may lead to the collapse of the solid in a splitting mode. With a newly developed numerical code, MFPA
2D (material failure process analysis), heterogeneous solids containing pre-existing single, triple and multi-pore-like flaws are numerically tested to study the mechanisms of compression-induced axial splitting. The interaction of growing cracks with the surfaces of the specimen and with each other in terms of stress field and failure modes is numerically analyzed in detail. Under uniaxial compressions, specimens containing holes in a diagonal array are more conducive to interaction than specimens containing holes arranged either in a horizontal or vertical array. Various parameters, such as hole diameter, specimen width, and the geometrical arrangement of hole locations, that characterize the growth process are quantified. Numerical results mimic the phenomena of experimentally observed splitting failure in brittle solids such as rocks in a realistic way.
An improved quick, easy, cheap, effective, rugged, and safe (QuEChERS) method combined with high-performance liquid chromatography (HPLC) coupled to diode array detection was established for the ...determination of fomesafen and quizalofop-p-ethyl in beans. It is simple and efficient and can be used in most laboratories. This method optimizes four chromatographic conditions, namely, mobile phase, mobile phase ratio, flow rate, and detection wavelength. The effects of extraction agent, extraction dose, extraction time, NaCl amount, and adsorbent on the pretreatment effect were studied. The recoveries were high (92.4–117.8%), and repeatability was good (relative standard deviation RSD ranged from 0.35 to 4.36%). The standard solutions ranged from 0.1 to 25 ?g/mL. The detection limits of fomesafen and quizalofop-p-ethyl were 0.005 and 0.003 mg/kg, respectively.
To explore the effects from the thread shapes of custom-made root-analogue implant (RAI) on distributions of von Mises stress around the peri-implant bone.
Five one-stage RAI three-dimensional finite ...element (FE) models with different thread shapes (V-shaped design, square design, buttress design, reverse buttress design and none thread design) and congruent bone were created through reverse engineering technology. The data of the five models were imported into the FE analysis software to calculate. A force of 100 N was applied parallelly and of 45° to the implant axis respectively. Analysis was performed to evaluate the von Mises stress distributions at the peri-implant regions with the help of the Ansys 16 software.
The von Mises stresses distributed mostly at the implant cervical regions and the tip ends of the threads on the cortical bone under oblique loading, while on the cancellous bone, the stresses concentrated mostly on the implant lateral cervical regions, the tip ends of the threads and the apical
Postoperative sore throat (POST) is a common complication after endotracheal intubation. We compared the effectiveness on POST of spraying the endotracheal tube (ETT) cuff with benzydamine ...hydrochloride, 10% lidocaine, and 2% lidocaine.
Three hundred seventy-two patients were randomly allocated into 4 groups. The ETT cuffs in each group were sprayed with benzydamine hydrochloride, 10% lidocaine hydrochloride, 2% lidocaine hydrochloride, or normal saline before endotracheal intubation. After insertion, the cuffs were inflated to an airway leak pressure of 20 cm H(2)O. Anesthesia was maintained with propofol. The patients were examined for sore throat (none, mild, moderate, or severe) at 1, 6, 12, and 24 hours after extubation.
The highest incidence of POST occurred at 6 hours after extubation in all groups. There was a significantly lower incidence of POST in the benzydamine group than 10% lidocaine, 2% lidocaine, and normal saline groups (P < 0.05) at each observation time point. At 6 hours after extubation, the incidence of POST was significantly lower in the benzydamine group (17.0%) compared with 10% lidocaine (53.7%), 2% lidocaine (37.0%), and normal saline (40.8%) groups (P < 0.05). The benzydamine group had significantly decreased severity of POST compared with the 10% lidocaine, 2% lidocaine, and normal saline groups (P < 0.05) at each observation time point. Compared with the 2% lidocaine and normal saline groups, the 10% lidocaine group had significantly increased severity of POST at 1, 6, and 12 hours after extubation. There were no significant differences among groups in local or systemic side effects.
Spraying benzydamine hydrochloride on the ETT cuff is a simple and effective method to reduce the incidence and severity of POST.
Abstract
Aims
Observational studies have suggested strong associations between sleep duration and many cardiovascular diseases (CVDs), but causal inferences have not been confirmed. We aimed to ...determine the causal associations between genetically predicted sleep duration and 12 CVDs using both linear and nonlinear Mendelian randomization (MR) designs.
Methods and results
Genetic variants associated with continuous, short (≤6 h) and long (≥9 h) sleep durations were used to examine the causal associations with 12 CVDs among 404 044 UK Biobank participants of White British ancestry. Linear MR analyses showed that genetically predicted sleep duration was negatively associated with arterial hypertension, atrial fibrillation, pulmonary embolism, and chronic ischaemic heart disease after correcting for multiple tests (P < 0.001). Nonlinear MR analyses demonstrated nonlinearity (L-shaped associations) between genetically predicted sleep duration and four CVDs, including arterial hypertension, chronic ischaemic heart disease, coronary artery disease, and myocardial infarction. Complementary analyses provided confirmative evidence of the adverse effects of genetically predicted short sleep duration on the risks of 5 out of the 12 CVDs, including arterial hypertension, pulmonary embolism, coronary artery disease, myocardial infarction, and chronic ischaemic heart disease (P < 0.001), and suggestive evidence for atrial fibrillation (P < 0.05). However, genetically predicted long sleep duration was not associated with any CVD.
Conclusion
This study suggests that genetically predicted short sleep duration is a potential causal risk factor of several CVDs, while genetically predicted long sleep duration is unlikely to be a causal risk factor for most CVDs.
Graphical Abstract
Causal associations of short and long sleep durations with 12 cardiovascular diseases: linear and nonlinear Mendelian randomization analyses in UK Biobank. All associations are significant at a Bonferroni threshold of P < 4.2E-03 (corrected for 12 outcomes). CVD, cardiovascular disease; SNP, single nucleotide polymorphism.
Subarachnoid hemorrhage (SAH) causes a high mortality rate and morbidity. It was suggested that oxidant stress plays an important role in neuronal injury after SAH. Therefore, we assessed the effect ...of curcumin on reducing cerebral vasospasm and neurologic injury in a SAH model in rat.
A double-hemorrhage model was used to induce SAH in rats. Groups of animals were treated with intraperitoneal injection of 20 mg/kg curcumin (curcumin group, n = 24) or dimethyl sulfoxide (vehicle group, n = 33), normal saline (SAH group, n = 34) or normal saline (sham group, n = 22), 3 h after SAH induction and daily for 6 days. Glutamate was measured before SAH induction and once daily for 7 days. Glutamate transporter-1, wall thickness and the perimeter of the basilar artery, neurologic scores, neuronal degeneration, malondialdehyde, superoxide dismutase, and catalase activities were assessed.
Changes of glutamate levels were lower in the curcumin group versus the SAH and vehicle groups, especially on day 1 (56 folds attenuation vs. vehicle). Correspondingly, glutamate transporter-1 was preserved after SAH in curcumin-treated rats. In the hippocampus and the cortex, malondialdehyde was attenuated (30% and 50%, respectively). Superoxide dismutase (35% and 64%) and catalase (34% and 38%) activities were increased in the curcumin rats compared with the SAH rats. Mortality rate (relative risk: 0.59), wall thickness (30%) and perimeter (31%) of the basilar artery, neuron degeneration scores (39%), and neurologic scores (31%) were improved in curcumin-treated rats.
Curcumin in multiple doses is effective against glutamate neurotoxicity and oxidative stress and improves the mortality rate in rats with SAH.
We report on the observation of new properties of secondary cosmic rays Li, Be, and B measured in the rigidity (momentum per unit charge) range 1.9 GV to 3.3 TV with a total of 5.4×10^{6} nuclei ...collected by AMS during the first five years of operation aboard the International Space Station. The Li and B fluxes have an identical rigidity dependence above 7 GV and all three fluxes have an identical rigidity dependence above 30 GV with the Li/Be flux ratio of 2.0±0.1. The three fluxes deviate from a single power law above 200 GV in an identical way. This behavior of secondary cosmic rays has also been observed in the AMS measurement of primary cosmic rays He, C, and O but the rigidity dependences of primary cosmic rays and of secondary cosmic rays are distinctly different. In particular, above 200 GV, the secondary cosmic rays harden more than the primary cosmic rays.
1 Department of Pharmacology, Faculty of Medicine, University of Hong Kong, Hong Kong; 2 Institut de Recherches Internationales Servier, Paris, France; and 3 Department of Physiology, Faculty of ...Medicine, Chinese University of Hong Kong, Hong Kong
Submitted 31 May 2005
; accepted in final form 15 July 2005
Preliminary studies suggested that previous exposure to acetylcholine (ACh) exerts a delayed inhibition of subsequent contractions mediated by endothelium-derived contracting factor (EDCF). To confirm this long-term inhibitory effect of ACh and to determine whether nitric oxide (NO) mediates the phenomenon, we suspended rings of spontaneously hypertensive rat (SHR) aortas in organ chambers for the recording of isometric force. The rings were incubated in the absence or presence of N -nitro- L -arginine methyl ester ( L -NAME; inhibitor of NO synthases) or 1 H -1,2,4oxadiazolo4,3- quinoxalin-1-one (ODQ; inhibitor of soluble guanylyl cyclase) before exposure to increasing concentrations of ACh or sodium nitroprusside (SNP) during contractions to phenylephrine. Thereafter, EDCF-mediated contractions to ACh or the calcium ionophore A-23187 were elicited. If the rings were preexposed to ACh or SNP, the subsequent ACh-induced EDCF-mediated contractions were reduced compared with those obtained in rings of the same arteries not previously exposed to either agent. ODQ did not affect the inhibition caused by preexposure to ACh but significantly reduced that caused by preexposure to SNP. Previous exposure to SNP reduced, whereas previous exposure to ACh did not affect, endothelium-dependent contractions to A-23187. Previous exposure to either ACh or SNP did not affect the contractions to the thromboxane mimetic U-46619. Thus ACh and SNP exert delayed inhibition of EDCF-mediated contractions via distinct pathways. The effect of ACh is NO independent and upstream of the increase in calcium concentration that triggers the release of EDCF. The effect of SNP is downstream of the calcium rise and is mainly NO dependent.
endothelium-dependent contractions; endothelium-derived contracting factors; spontaneously hypertensive rats; nitric oxide
Address for reprint requests and other correspondence: P. M. Vanhoutte, Dept. of Pharmacology, Univ. of Hong Kong, 2/F, Laboratory Block, Faculty of Medicine Bldg., 21 Sassoon Road, Pokfulam, Hong Kong (e-mail: vanhoutte.hku{at}hku.hk )
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