Effect of pretension on the mechanical behaviour of bolted rock

ABSTRACT: A stepwise pull-and-shear test (SPST) scheme that numerically analyses the mechanical behaviour of bolted rock joints subjected to simultaneous pull-shear loading. The SPST scheme allows us to identify the optimum pretension stress magnitude at which the bolting system exhibits its ultimate shear capacity. The micro-mechanical properties of grout and bolt-grout interface were calibrated against the laboratory data. The micro-mechanical parameters of rock were calibrated against the laboratory data of coal and shale, and the micro-mechanical properties of rock joint interface were identified by reproducing the laboratory behaviour of coal-shale interface under the direct shear test. Then, the SPST scheme was employed to study the effect of pretension stress magnitude on the macroscopic behaviour of bolted coal. The numerical results revealed that at yield pretension stress magnitude (pull-out test) the rock bolting system could exhibit its ultimate shear performance

Failure response of rocks under different cyclic loading histories

The post-failure instability of rocks was investigated through an extensive experimental study under four different loading histories, including the monotonic quasi-static loading, single-level systematic cyclic loading (SLSCL), multi-level systematic cyclic loading (MLSCL), and post-peak cyclic loading (PPCL). The lateral strain-controlled and double-criteria damage-controlled testing methodologies were implemented for the experiment. A combined postpeak Class I-II behavior to different extents was detected for soft to strong rocks, while the unstable fracture propagation was more dominant for stronger rocks under monotonic loading. Additionally, rocks exhibited more self-sustaining behavior under MLSCL history with increasing the number of cycles before the failure point. On the other hand, the results of the SLSCL tests revealed that rock brittleness reaches its maximum value by applying systematic cyclic loadings at stress levels close to the monotonic strength. However, the effect of post-peak cyclic loading (PPCL) history on the post-failure response of rocks was negligible

Ocular Artifact Detection and Removing from EEG by wavelet families: A Comparative Study

The Electroencephalogram (EEG) is a biological signal that represents the electrical activity of the brain. Biological artifacts like ocular artifact (OA) are one of the main interferences in EEG recordings. Eye blinks and movements of the eyeballs produce a signal known as electrooculogram (EOG) that these are 10 to 100 times stronger than the EEG signal. Due to the frequency range of EEG signal and OA which has overlapping with each other, identify and removing of the EOG artifacts are one of the main challenges for researchers, because an incorrect denoising may lose some of the important information of EEG signals. In this context, our aim is to propose a technique based on wavelet transform for accurate identification of the blink artifact zone and removal of EEG signals. We propose using absolute value of signal reconstructed details for blink zone detection and the efficiency of wavelet families to remove the blink artifact which is evaluated by calculating the mean squared error (MSE) between denoised and clean EEG signals and comparing with the results before and after artifact removing show that db7, sym7, coif5, rbio1.5 and dmey at 4th level are preferable and effective in blink artifact zone detection and db7, coif5, dmey, db5 and db9 respectively provide the best result for blink artifact removing with minimum loss important information. Keywords: EEG, EOG, OA, Wavelet transform, MS

COMPARATIVE STUDY OF NURSING GROUP PERSONNEL NUMBER TO ACTIVE BED OF HOSPITALS AFFILIATED TO YASUJ MEDICAL SCIENCES UNIVERSITY WITH EXISTING STANDARDS AND FACTORS EFFECTIVE ON IT IN 2015

Introduction: Most problems of institutions providing treatment services in health systems (hospitals) are due to shortage of human force or its unsuitable distribution. Among the most important ways of increasing employing nurses as the major part of hospitals human forces is standardization of quantity and distribution of this valuable source. Methods: This study is applied descriptive and of cross sectional type. The research sample and society is nursing group personnel affiliated to Yasuj Medical Sciences University. Data collecting tool is some tables containing number, gender combination and type of employment of nursing personnel (library model) and effective factors like reducing working hours rate due to efficiency law, increasing the number of hospitalization days after health system evolution plan were studied. Information after collecting was analyzed using SPSS software and using descriptive statistical tests. Results: The obtained results indicate that the ratio of nurse to active bed number is not similar to standards and there is a difference. The rate of working hours reduction due to efficiency law and the number of hospitalization days results in need to more personnel after health system evolution. Conclusion: The obtained results show that the required nursing force in the hospitals affiliated to Yasuj Medical Sciences University in some wards is not according to the standard of Ministry of Health and systematic attitude standard

COMPARATIVE STUDY OF NURSING GROUP PERSONNEL NUMBER TO ACTIVE BED OF HOSPITALS AFFILIATED TO YASUJ MEDICAL SCIENCES UNIVERSITY WITH EXISTING STANDARDS AND FACTORS EFFECTIVE ON IT IN 2015

Introduction: Most problems of institutions providing treatment services in health systems (hospitals) are due to shortage of human force or its unsuitable distribution. Among the most important ways of increasing employing nurses as the major part of hospitals human forces is standardization of quantity and distribution of this valuable source. Methods: This study is applied descriptive and of cross sectional type. The research sample and society is nursing group personnel affiliated to Yasuj Medical Sciences University. Data collecting tool is some tables containing number, gender combination and type of employment of nursing personnel (library model) and effective factors like reducing working hours rate due to efficiency law, increasing the number of hospitalization days after health system evolution plan were studied. Information after collecting was analyzed using SPSS software and using descriptive statistical tests. Results: The obtained results indicate that the ratio of nurse to active bed number is not similar to standards and there is a difference. The rate of working hours reduction due to efficiency law and the number of hospitalization days results in need to more personnel after health system evolution. Conclusion: The obtained results show that the required nursing force in the hospitals affiliated to Yasuj Medical Sciences University in some wards is not according to the standard of Ministry of Health and systematic attitude standard

Stabilization of a highly expansive soil using waste-tire-derived aggregates and lime treatment

This study investigates the combined efficacy of waste-tire-derived aggregate (TDA) materials and hydrated lime on the compactability, compressive strength and swelling potential of a highly expansive soil from South Australia. A total of 21 mix-designs, covering a comprehensive range of soil–TDA–lime combinations, were examined through standard Proctor compaction, unconfined compressive strength (UCS) and oedometer swell tests. The mobilized UCS exhibited a ‘rise–fall’ behavior, peaking at 5% TDA content and subsequently decreasing (monotonically) for higher inclusions of TDA. Increasing the TDA mean particle size (from 1.67 to 3.34 mm) also contributed positively to the UCS development. Addition of TDA to the soil/soil–lime-blends produced notable reductions in the swelling potential; the reduction was primarily governed by higher TDA contents, and, to a lesser degree, for larger TDA mean particle sizes. However, the role of TDA particle size in reducing swelling was found to be more significant than that of enhancing the UCS. As expected, lime treatment of the soil–TDA blends provided major further improvements to the UCS and swelling potential reduction; the achieved UCS improvements being positively proportional to the lime content and curing time. In view of the experimental results, soil–lime blends containing TDA to soil–lime mass ratios of up to 10% (preferably employing coarse-sand-sized equivalent TDA) can be deemed as suitable choices (capable of adequately mitigating the swelling potential, while simultaneously enhancing the UCS). © 2022 The Author

Improving workability of cement paste backfill using new binders

In this study effects of binder type and content and curing time on the compressive strength development of cement paste backfill (CPB) is investigated. Moreover, the effects of binder type and content and water content on the rheological properties of CPB material were studied. To undertake an experimental study, tailings of a copper mine in South Australia are mixed with binder and water. A new slag-cement called Mine Cement (MC) and ordinary Portland cement (PC) are used as the primary binder materials. Furthermore, fly ash (FA) is used as an additive to reduce the amount of the cement. Some CPB samples were cured under pressure to be more representative of the field conditions. MC exhibited better performance that PC regarding compressive strength development. Fly ash improved the compressive strength of CPB. However, this binder observed to be much less cementitious compare to MC. Strength performance of the CPB sample significantly improved when there were cured under pressure. Based on the results obtained from the test undertaken using a rheometer, it was found that increasing the water content results in lower yield stress. The results also show that MC improves the rheological properties of the CPB

Improved shear strength performance of compacted rubberized clays treated with sodium alginate biopolymer

This study examines the potential use of sodium alginate (SA) biopolymer as an environmentally sustainable agent for the stabilization of rubberized soil blends prepared using a high plasticity clay soil and tire-derived ground rubber (GR). The experimental program consisted of uniaxial compression and scanning electron microscopy (SEM) tests; the former was performed on three soil–GR blends (with GR-to-soil mass ratios of 0%, 5% and 10%) compacted (and cured for 1, 4, 7 and 14 d) employing distilled water and three SA solutions—prepared at SA-to-water (mass-tovolume) dosage ratios of 5, 10 and 15 g/L—as the compaction liquid. For any given GR content, the greater the SA dosage and/or the longer the curing duration, the higher the uniaxial compressive strength (UCS), with only minor added benefits beyond seven days of curing. This behaviour was attributed to the formation and propagation of so-called “cationic bridges” (developed as a result of a “Ca2+/Mg2

Improvement of post-thawed sperm quality in broiler breeder roosters by ellagic acid-loaded liposomes

P. 440–446Liposomes could improve the delivery of substances to sperm. This study was conducted to investigate the effect of the antioxidant ellagic acid and ellagic acid-loaded liposomes on post-thawed sperm quality in broiler breeder roosters. Semen was diluted in Beltsville extender containing ellagic acid or ellagic acid-loaded liposomes (ellagic acid at 0 (control), 0.5, 1, and 2 mM) and cryopreserved. Sperm quality was evaluated post-thawing: motility characteristics (Computer-Assisted Semen Analysis), membrane functionality (HOS test), abnormal morphology, mitochondrial activity (Rhodamine 123), apoptotic status (Annexin V/Propidium iodide), malondialdehyde, and antioxidant activities (glutathione peroxidase (GPx), superoxide dismutase (SOD), and total antioxidant capacity (TAC)). The results showed that 1 mM ellagic acid-loaded liposomes improved total motility, membrane functionality, and viability comparing to 0.5 and 2 mM ellagic acid, 2 mM ellagic acid-loaded liposomes, and control group. Mitochondrial activity was significantly higher for 1 mM ellagic acid-loaded liposomes compared to the rest of the treatments, except 1 mM ellagic acid. Ellagic acid at 1 mM in both forms significantly increased GPx and TAC after freeze-thawing (no significant variation for SOD), and also yielded the lower proportion of apoptotic and dead cells. In conclusion, ellagic acid improved post-thawed sperm quality in broiler breeder roosters. The use of liposomes could further enhance the effects of ellagic acid.S

Conservative Management of Periapical Cementoblastoma: A Case Report

As a rare ectomesenchymal neoplasm, benign cementoblastoma comprises less than 6% of all odontogenic tumors. The typical treatment plan involves surgical excision and extraction of the affected tooth. Limited evidence, however, suggests the conservative management of this condition as the best treatment. This article discusses the case of a 32-year-old man who had benign cementoblastoma and underwent conservative treatment. The diagnosis was established based on clinical and radiological features analyses. Root canal therapy was performed on the tooth, followed by enucleation, curettage, apicoectomy, and guided bone regeneration (GBR) 30 days later. After a year of follow-up, there was no recurrence, and the tooth was in healthy conditions. These findings demonstrated that the tooth affected by cementoblastoma can be saved. It was treated conservatively to preserve the patient’s oral health and masticatory function