Nanoclay Performance on Resistance of Clay under Freezing Cycles

This study aims to investigate effect of nanoclay on resistance of the exposed clay soils in freezing in vitro conditions. The clay sample was selected from the considered land. Then they were mixed on water in 1.5, 3, 4.5 and 6 percents as well as without nanoclay. There were prepared cylinders with 3.81 cm diameter and 7.62 cm height, which they have been placed in conditions without freezing, one cycle, two cycles and three cycles of freezing. Then they were tested under uniaxial experiment. Then they were analyzed by SPSS software. The results show that adding nanoclay with 1.5, 3, 4.5 and 6 percents will reduce soil strength during freezing cycles. It can be occurred because adding nanoclay will result to increase special surface of the samples; consequently, increasing electrical load increases water absorption, which it can be partly cause of non-effective increasing nanoclay in soil resistance. There is also a significant difference between pressure strength of soils with lower humidity and those with higher humidity. It confirms that increasing humidity decreases strength level, which increasing water absorption of samples by nanoclay is reason of decreasing strength. There is an inverse significant relationship between increasing nano and soil water absorption, which its reason may be that adding nanoclay because of increasing samples special surface and consequently, increasing electricity load will increase water absorption and samples\u2019 plasticity. It can be expected that samples\u2019 permeability will decline by increasing their plasticity. There is also a significant relationship between increasing nano and soil liquid and doughiness limit that its reason can be increasing rate of water absorption in samples due to presence of nanoclay

Influence of Near Vision Tasks on Intraocular Pressure in Normal Subjects and Glaucoma Patients

Purpose: To investigate the effect of static accommodative tasks on intraocular pressure (IOP) of glaucomatous and normal eyes. Methods: Four groups of subjects categorized as primary open-angle glaucoma (POAG), primary angle-closure suspects (PACS), normal age-matched controls, and normal young adults (NYA; age <40 years) were enrolled. The baseline IOPs were measured after the subjects were looking at a distant target for 15 min. Static accommodation was obtained by execution of near vision tasks (reading at 33 cm in daylight [300 lux] for 60 min). IOPs were measured at 15, 30, 45, and 60 min intervals while accommodating and then measured again after 15 min of relaxing accommodation while looking at a distant target. Results: One-hundred and eighteen eyes of 98 subjects were recruited. The study groups consisted of the following categories: 25 POAG (46 eyes), 24 PACS (47 eyes), 25 matched controls (50 eyes), and 24 NYA (48 eyes). Within all groups, the mean IOP decreased throughout the accommodation period at all time points. Maximum IOP reduction after accommodation was detected at the 30-min time among the POAG subjects, at the 45-min time in the PACS and matched control groups, and at 15 min after the relaxation of accommodation in the NYA group. IOP reduction levels showed no statistically significant difference among POAG, PACS, and the normal matched groups in their response to accommodation. However, NYA had significantly lower IOP and greater IOP reduction after the resting period (relaxation of accommodation). Conclusion: Static accommodative tasks can significantly reduce IOP in normal, POAG, and PACS individuals. Encouraging glaucoma patients to practice periodical near vision tasks could be viewed as an adjunctive measure for glaucoma management

Clinical Study Endovascular Treatment of Intracranial Artery Dissection: Clinical and Angiographic Follow-Up

Background. Intracranial artery dissections are rare and many controversies exist about treatment options. The aim of this study was to evaluate the efficacy and safety of the endovascular approach in patients with an intracranial dissection presenting with different symptoms. Methods. We prospectively evaluated the clinical features and treatment outcomes of 30 patients who had angiographically confirmed nontraumatic intracranial dissections over 4 years. Patients were followed up for 17 months, and their final outcomes were assessed by the modified Rankin Score (mRS) and angiography. Results. Sixteen (53.3%) patients had a dissection of the anterior circulation, whereas 14 (46.7%) had a posterior circulation dissection. Overall, 83.3% of the patients suffered a subarachnoid hemorrhage (SAH). Grade IV Hunt and Hess score was seen in 32% of the SAH presenting cases. Parent artery occlusion (PAO) with coil embolization was used in 70% of the cases. The prevalence of overall procedural complications was 23.3%, and all were completely resolved at the end of follow-up. No evidence of in-stent occlusion/stenosis or rebleeding was observed in our cases during follow-up. Angiography results improved more frequently in the PAO with coil embolization group (100%) than in the stent-only-treated group (88.9%) ( = 0.310) and the unruptured dissection group (5/5, 100%) in comparison with the group that presented with SAH (95.8%) ( = 0.833). Conclusion. Favorable outcomes were achieved following an endovascular approach for symptomatic ruptured or unruptured dissecting aneurysms. However, the long-term efficacy and durability of these procedures remain to be determined in a larger series

Experimental observations relative to repeatability of wave propagation tests

International audienceThe results of a prospective experimental study of wave propagation into granular materials using bender – extender elements are presented. The experiments mainly focus on the repeatability of the pulse tests into multiple samples, which has not been so much investigated until now, in order to assess the degree of relevance of a frequency analysis of the signals. The repeatability is first assessed by multiplying the pulse tests into one sample: that method is currently carried out to decrease the level of noise in the electrical signals. More interesting is the repeatability of pulse tests into two samples prepared in the same conditions and presenting the same macroscopic parameters (void ratio in particular). The interaction between the wave and the granular assembly induces two distinct parts in the output signals: (i) the coherent part, usually contained in the first period of the output signals, representative of the continuous effective medium and similar in different samples and (ii) an incoherent part attributed to differences into the fabric and evolution of the fabric of distinct samples. The main conclusion is that time analysis which doesnot consider the content of the output signals is highly repeatable whereas frequency analysis depends on the sample fabric

Effect of grains roughness on waves velocities in granular packings

International audienceThe effect of particles roughness on wave velocities is investigated in granular materials using bender-extender elements. The roughness of the particles was modified by a chemical degradation process of initially smooth beads. Wave velocities were calculated along isotropic stress paths from 100 to 500 kN/m 2 in order to compare these experimental results to theoretical predictions by Hertz or previous results presented in the literature. Our results show a little effect of the surface roughness on the longitudinal wave velocities but a notable effect on the shear wave velocities