Evaluation of volumetric strain quantities and types of volumetric strain curves under failure-deformation process of hard brittle rocks

Purpose. The aim of this work is to show whether or not a relationship exist among the different volumetric strain quantities and to assess also whether the volumetric quantities are related to the different types of volumetric strain curves under failure-deformation process of hard brittle rocks. Methods. Tests were conducted to determine the post failure stress-strain curves of different 83 rocks types under uniaxial compression using a closed loop servo-controlled testing system in accordance to ISRM (International Society for Rock Mechanics) suggested standards. Findings. The result show that the volumetric strains quantities are related by power form law. It was established that there is a connection between the volumetric strains quantities and the types of the volumetric strains curves. The first type volumetric strain curves contains the Class I and progress to Class II while the type three volumetric strain curves are entirely Class II rock. Originality. No experimental results have been published, which describe the connection between the type of volumetric strain curves and volumetric strain quantities or attempt to relate the volumetric strain quantities with type of post-failure stress-strain characteristic curves response of rocks under uniaxial compression. Most researchers in rock mechanics studies have so far been focused on the crack damage stress (σcd) and uniaxial compressive strength (σc) of characteristic stress levels during compression in which σcd = Ɛcd and σcd = σc to study deformation behavior of rocks. Practical implications. It was also observed that the difficulty in obtaining the post-failure curves increases from type one to type two and type three volumetric strain curves respectively. It could guide personnel conducting tests using closed-loop servo-controlled testing system, if dangerous situation or equipment damage could occur (especially with the third type deformation process) so that testing is performed safely. It could also be useful in understand-ding the total process of specimen deformation and estimation of the rocks brittleness (e.g. brittle for Class II and less brittle or ductile for Class I).Мета. Встановлення та оцінка взаємозв’язку між різними величинами та типами кривих об’ємної деформації у процесі одноосьового стиску жорстких крихких порід. Методика. Повні криві напруження й деформації визначалися при необмеженому одноосьовому випробуванні на стиск з використанням системи сервокерованого контролю із замкнутим контуром для оцінки механічних властивостей 83 різних типів порід (53 вивержених, 10 осадових і 20 метаморфічних). Процедури випробувань для визначення повних кривих напружень і деформацій гірських порід, а також параметрів їх міцності проводилися відповідно до запропонованого ISRM методу. Результати. Дослідження показали, що залежність величин об’ємної деформації описується степеневим законом. Встановлено, що існує зв’язок між величинами об’ємної деформації та типами кривих, що її описують. Перший тип кривих об’ємної деформації відповідає породам класу I з переходом до класу II, у той час як криві третього типу повністю відповідають породам класу II. Наукова новизна. Вперше експериментальним шляхом встановлено взаємозв’язок між типами кривих об’ємної деформації та її величиною. Зроблені перші спроби пов’язати величину об’ємної деформації з кривими напруження – деформації порід після руйнування при одноосьовому стиску, у той час як попередні результати отримані під час стиску. Практична значимість. Складність отримання кривих для стану породи після руйнування збільшується з переходом від 1 типу кривих об’ємної деформації до 2 і 3 типу, що є важливим аспектом для безпечного тестування порід персоналом. Результати роботи представляють інтерес для розуміння загальних процесів деформації зразка та оцінки крихкості порід (наприклад, крихкі породи класу II і менш крихкі або більш пластичні породи класу I).Цель. Установление и оценка взаимосвязи между различными величинами и типами кривых объемной деформации в процессе одноосного сжатия жестких хрупких пород. Методика. Полные кривые напряжения и деформации определялись при неограниченном одноосном испытании на сжатие с использованием системы сервоуправляемого контроля с замкнутым контуром для оценки механических свойств 83 различных типов пород (53 изверженных, 10 осадочных и 20 метаморфических). Процедуры испытаний для определения полных кривых напряжений и деформаций горных пород, а также параметров их прочности проводились в соответствии с предложенным ISRM методом. Результаты. Исследование показали, что зависимость величин объемной деформации описывается степенным законом. Установлено, что существует связь между величинами объемной деформации и типами описывающих ее кривых. Первый тип кривых объемной деформации соответствует породам класса I с переходом к классу II, в то время как кривые третьего типа полностью соответствуют породам класса II. Научная новизна. Впервые экспериментальным путем установлена взаимосвязь между типами кривых объемной деформации и ее величиной. Предприняты первые попытки связать величину объемной деформации с кривыми напряжения – деформации пород после разрушения при одноосном сжатии, в то время как предыдущие результаты получены во время сжатия. Практическая значимость. Сложность получения кривых для состояния породы после разрушения увеличивается по мере перехода от 1 типа кривых объемной деформации ко 2 и 3 типу, что является важным аспектом для безопасного тестирования пород персоналом. Результаты работы представляют интерес для понимания общих процессов деформации образца и оценки хрупкости пород (например, хрупкие породы класса II и менее хрупкие или более пластичные породы класса I).We appreciated Rock Engineering Department, Aalto University Helsinkin Finland for granting permission to determine the post-failure curves of the samples using their closed-loop servo-controlled machine

Strength and strain quantities under brittle compression process of hard rocks

Purpose. To examine the relationships between strength properties and strain quantities associated with the brittle compression process of hard brittle rocks. Methods. The data used in this paper were obtained from laboratory uniaxial compression tests carried out on 84 different types of hard rocks in accordance with Ulusay (2015) proposed standards. The strength properties and the strain quantities were coordinated so that each of the strain quantities or their ratios is compared individually with the strength properties of the rocks as for their relationship. Findings. In all the cases the relationships between the strain ratios and the strength parameters are stronger than when compared with individual strain quantities. A threshold level for strain ratio Ɛvf / Ɛcd may be assumed as the limit for fracture initiation above which the rock may experience brittle fracture failure. Originality. Scientific sources demonstrate few laboratory studies as for strength properties-strain quantities ratio. Most of the published research has been concentrated on crack damage stress (σcd) and uniaxial compressive strength (σc) of characteristic stress levels during compression. The paper has performed detailed analysis of the problem using experimental results of the relationships between strength properties and strain quantities under the deformation process of hard rocks. Practical implications. The relationships can improve our knowledge to evaluate correctly the stability of excavations, design of stable structures such as tunnels and excavations for mining and civil engineering purposes.Мета. Вивчення зв’язків між міцнісними характеристиками та величинами деформацій, що виникають у процесі крихкого стискання твердих порід. Методика. На підставі лабораторних тестів на одноосьове стискання, проведені з 84 видами твердих гірських порід, отримано результати їх міцності на одноосьове стискання, модулі пружності та коефіцієнти Пуассона. Для випробувань використана сервокерована система контролю із замкненим контуром (випробувальна машина МТS 815). Параметри міцності оцінюються відповідно до запропонованих стандартів (Ulusay, 2015). Результати. Експериментальним шляхом встановлено кореляційні взаємозв’язки критичної об’ємної деформації при втраті міцності з її безпосередніми параметрами (міцність на одноосьове стискання, модуль пружності, коефіцієнт Пуассона). Встановлено, що у всіх випадках взаємозв’язок між відносинами деформації та параметрами міцності сильніший, ніж у порівнянні з окремими величинами деформації. Граничний рівень для деформаційного співвідношення Ɛvf /Ɛcd може бути прийнятий як межа початку руйнування, вище якої гірська порода може піддаватися крихкому руйнуванню. Наукова новизна. Попередні дослідження були сфокусовані у більшості випадків при вивченні напружень розриву (σcd) та одноосьовому компресійному стисканні (σc) характерних рівнів напружень під час стискання й носили теоретичний характер. У цій статті експериментальним шляхом були уточнені результати дослідження співвідношень і взаємозв’язків між міцнісними характеристиками та величинами деформації у процесі деформації твердих гірських порід. Практична значимість. Встановлені співвідношення міцнісних та деформаційних величин сприяють удосконаленню знань щодо коректної оцінки стійкості проведених гірничих виробок, проектування стійких споруджень, таких як тунелі, розробки в гірництві, промисловому та цивільному будівництві.Цель. Исследование взаимосвязей между прочностными характеристиками и величинами деформаций, возникающими в процессе хрупкого сжатия твердых хрупких пород. Методика. На основе лабораторных тестов на одноосное сжатие, проведенных с 84 видами твердых горных пород, получены результаты их прочности на одноосное сжатие, модуля упругости и коэффициента Пуассона. Для испытаний использовалась сервоуправляемая система контроля с замкнутым контуром (испытательная машина MTS 815). Параметры прочности оценивались в соответствии с предложенными стандартами (Ulusay, 2015). Результаты. Экспериментальным путем установлены корреляционные взаимосвязи критической объемной деформации при потере прочности с ее непосредственными параметрами (прочность на одноосное сжатие, модуль упругости, коэффициент Пуассона). Установлено, что во всех случаях взаимосвязь между отношениями деформации и параметрами прочности сильнее, чем по сравнению с отдельными величинами деформации. Пороговый уровень для деформационного соотношения Ɛvf /Ɛcd может быть принят как граница начала разрушения, выше которой горная порода может подвергаться хрупкому разрушению. Научная новизна. Предыдущие исследования были сфокусированы в большинстве случаев на изучении напряжения разлома (σcd) и одноосном компрессионном сжатии (σc) характерных уровней напряжения во время сжатия и носили теоретический характер. В этой статье экспериментальным путем были уточнены результаты исследования соотношений и взаимосвязи между прочностными характеристиками и величинами деформации в процессе деформации твердых горных пород. Практическая значимость. Установленные соотношения прочностных и деформационных величин способствуют совершенствованию знаний относительно корректной оценки устойчивости проведенных горных выработок, проектированию устойчивых сооружений, таких как туннели, разработки в горном деле, промышленном и гражданском строительстве.The Rock Engineering Laboratories of Rock Engineering Department of Aalto University Helsinki Finland and School of Mining Engineering Wits University South Africa are appreciated for allowing part of this work to be done there

Investigation of the relationship between fragmentation and brittleness of rock, in particular class II rock type

The aim of this research is to investigate the relationship between fragmentation and brittleness of rock by taking into account the influence of the Class II characteristic behaviour of the rocks have on this relationship. Fragmentation of rock under compressive failure depends on its self-sustaining failure and the energy available in the post-failure region to shatter the rock. The fragmentation produced under this condition depends to a large extent on the energy available to cause fragmentation and on the brittleness of the rock. From review of the literature, it appears that no research has attempted to link brittleness and fragmentation. Rock failure under dynamic loading conditions, such as in blasting, rockbursts, crushing, and milling, as well as during conventional unconfined compressive strength testing of rock specimens and the subsequent fragments size distribution is a little-understood phenomenon. This relationship will be helpful in the solution to many practical mining and civil engineering problems. This includes the prediction of optimal fragmentation and the design of stable structures as a result of dynamic processes particularly associated with fragmentation. The research carried out involved the analysis of rock parameters determined from different rock Classes (Class I and Class II) under destructive tests using a soft testing machine and a closed loop servo-controlled testing machine (stiff machine). The tests were conducted according to ISRM suggested methods at the Genmin Laboratory, Wits University while the post-failure stress-strain curves estimation were done using a closed loop servo-controlled testing machine at the Rock Engineering Department at Aalto University Finland. In addition, non-destructive tests were conducted with the output being monitored using a dual-beam cathode ray oscilloscope. From the destructive tests, the static parameters were determine

Evaluation of poultry manure, cattle dung, water and cattle urine-based composts on soil chemical properties, growth and yield of Amaranthus cruentus L.

The inclusion of cattle urine in compost preparation will improve compost quality, particularly with respect to nutrient composition. Field experiments were conducted at the organic farm of the Federal University of Agriculture, Abeokuta, Ogun State in 2014 and 2016 to evaluate the ef­fects of water and cattle urine composts, sole poultry manure and cattle dung on post-harvest soil properties, growth and yield of Amaranthus cruentus. Treatments used were: compost derived from poultry manure + rice husk with water as source of moisture at 2.5, 5.0, 6.5 and 7.5 t ha-1, (PRW2.5, PRW5, PRW6.5 and PRW7.5 respectively), compost derived from poultry manure + rice husk with cattle urine as source of moisture at 2.5, 5.0, 5.4 and 7.5 t ha-1 (PRU2.5, PRW5, PRW5.4 and PRW7.5 respectively) and control. Post-harvest soil was analyzed for chemical properties, agronomic parameters and yield of Amaranthus cruentus were evaluated. Results showed that the application of PRU5.4 resulted in highest values for most of the agronomic parameters in both years, while the competition for highest values of post-harvest soil parame­ters was between PRW5 and PRW6.5. The highest values of Amaranthus cruentus yield in both years resulted from the application of PRU5.4 and PM3

Utterances Functions and the Negotiation of Power in Courtroom Interactions: A Survey of High Courts in Ota, Ogun State, Nigeria

This study investigated the negotiation of power and the pragmatic implication of utterances in courtroom proceedings in Ota, Ogun State, Nigeria. Teun van Dijk’s approach to Critical Discourse Analysis and Jacob Mey’s Pragmatic Acts theory are theoretical frameworks adopted in the study. Data was collected from five High Courts’ trial cases in Ota, Ogun State, Nigeria. In the High Courts, the Judge wills the highest power in the court and controls the proceedings in the High court. The Judge dominates the Counsels, and litigants while the Counsels dominate the litigants. The litigants are observed to be at the receiving end of the discourse as they accept and legitimize this power and dominance. Certain pragmatic acts such as acknowledging, protesting, accusing, justifying were deduced from the discourses. The role played by courtroom participants in the social structure influences power relations in courtroom proceedings. Thus, power, dominance, inequality and hegemony are notable features in the language of High Court proceedings in Ota

Knowledge of Computer Vision Syndrome among computer users in the workplace in Abuja, Nigeria

Quantitative, descriptive, cross-sectional study was conducted to determine the level of knowledge and extent of Computer Vision Syndrome (CVS) among computer users in the Securities and Exchange Commission (SEC), Abuja, Nigeria. Structured questionnaires were administered to 100 computer users aged between 18 and 40 years. The study findings revealed that 40 respondents (40%) were aware of CVS and 27 (27%) of them had knowledge of the disorder. 74 (74%) of the respondents experienced at least one symptom of CVS. Headache and eyestrain were the most common symptom of CVS among the population. The study also revealed that the internet (accounting for 50%) was the major source of information about CVS awareness. The study concluded that 27% knowledge level is too low and much emphasis is needed to educate the people at risk of CVSHealth StudiesM.A. (Public Health

Attitude of Civil Servants Towards the Use of Research Information in Policymaking in Selected Ministries in Lagos State, Nigeria

Information is very essential in any organization especially in a government based environment where information are needed for policy making. However, some of the instruments used for getting information are not well managed by the civil servants who are the custodian of this research information. This study investigated the attitude of policymakers in terms of the types, availability and accessibility of research information in making policy. Focusing particularly on the types of research information needed by senior civil servants in making policies, frequency of use of research information source, accessibility of information for decision making and the challenges encountered in the course of using them. The descriptive research method was adopted, using a pre-tested self-administered questionnaire to gather information from 166 senior civil servants randomly selected from selected ministries in Lagos state, as data collection instrument. Results indicated that information provided by ones ministry, information on project implemented by ones ministry , information on infrastructural development and information on human resources and skills available at ones ministry are the most used information by policymakers in making policy. The study also showed that internal files, colleagues or superior, newspaper, government publication and internet are the most frequently used and accessible information sources for policymaking. Impracticability of research recommendation politically and financially, too much information to absorb and contradictions in information from different researchers are the major constraints to research output. The study recommended among other suggestions that policymakers must consider wider ranges of research information sources for effective policy making

Patrons’ Perception of Service Delivery of Medical Tourism Sites in Metropolitan Lagos

This study examined the patrons' perception of service delivery of medical tourism sites in Lagos metropolis, Nigeria. Data were collected through questionnaire administration. Systematic sampling technique was employed to select 15 specialized private hospitals and 14 Public hospitals in the study area, resulting to a sample size of 29 hospitals. Ten (10) patrons were contacted in each of the selected hospitals; consequently, 290 patrons were sampled. Data collected were analyzed using descriptive (Patron Satisfaction Index (PSI)) and inferential statistic (Multiple Regression Analysis). Findings established that patrons are satisfied with Efficiency of Medical Treatment (PSI = 3.55), Satisfactory service (PSI = 3.87), and Standard level of medical staff (PSI = 3.46). While also expressed their dissatisfaction towards cost of treatment (PSI = 3.04), waiting time at the hospital (PSI = 2.92), and Good Laboratory (PSI= 3.31). Service delivery influences decision of patrons on choice of hospital to visit, this is as established by the result of multiple regression model R² = 0.898 (89.8%), F (7 & 282) = 355.004, p ≤.000. The study concluded that there exists a strong positive correlation between service delivery and destination choice. Keywords: Tourism, Medical Tourism, Hospital, Healthcare Service Delivery, Patrons’ Perceptio

Positivity yield of HIV index testing services from selected healthcare facilities in Ondo State, southwest Nigeria

Background: Index testing is a voluntary process whereby HIV seropositive clients are counselled and, after obtaining consent, their sexual and needle sharing partners are offered HIV testing services. Index testing has been associated with high HIV positivity yield. The aim of this study is to determine the positivity yield and identify factors influencing the yield from index testing strategy in selected healthcare facilities in Ondo State, southwest Nigeria. Methodology: Six public hospitals in Ondo State with the highest HIV clients currently on treatment were selected. Records of all clients newly diagnosed to be HIV positive at the selected facilities from June 2018 to September 2019, and who had an outcome for index testing services were reviewed. Data were collected using a chart abstraction template from the index testing registers. Information collected included age and gender of the index clients and their partners, method of referral and notification of partners, HIV test results of partners and linkage status of new HIVpositive partners. Data analyses were done using the Statistical Package for the Social Sciences (SPSS) software version 24.0. Chi-square was used to test association between variables at a significance level of p<0.01. Results: The records of a total of 904 index clients and their partners were reviewed with partner elicitation ratio of 1:1. The mean ages of index clients and their partners were 38.52±10.96 and 38.98±10.79 years respectively, and majority of the index clients (34.6%) and partners (35.5%) were in the 35-44 years age group. A total of 548 index clients were females (60.6%) while 528 of their partners were males (58.4%), indicating  predominantly heterosexual (96.4%) and few homosexual (lesbian) relationships (3.6%). One-fifth (20%) of partners tested positive for HIV andwere all (100%) linked to antiretroviral therapy (ART). The HIV positivity rate in partners of male index clients (26.9%) was significantly higher than in partners of female index clients (15.5%) (p<0.01). Partner referral method was mostly through assisted referral (56%) and most (82%) were contacted by the index clients through phone. Conclusion: Due to its high positivity yield, index testing is a veritable strategy to increase HIV case detection and linkage to ART. Hence, proper deployment of index testing will be critical to improving ART coverage and achieving epidemiological control. Keywords: HIV, client; partner; index testing; ART; southwest Nigeri

Effect of early tranexamic acid administration on mortality, hysterectomy, and other morbidities in women with post-partum haemorrhage (WOMAN): an international, randomised, double-blind, placebo-controlled trial

Background Post-partum haemorrhage is the leading cause of maternal death worldwide. Early administration of tranexamic acid reduces deaths due to bleeding in trauma patients. We aimed to assess the effects of early administration of tranexamic acid on death, hysterectomy, and other relevant outcomes in women with post-partum haemorrhage. Methods In this randomised, double-blind, placebo-controlled trial, we recruited women aged 16 years and older with a clinical diagnosis of post-partum haemorrhage after a vaginal birth or caesarean section from 193 hospitals in 21 countries. We randomly assigned women to receive either 1 g intravenous tranexamic acid or matching placebo in addition to usual care. If bleeding continued after 30 min, or stopped and restarted within 24 h of the first dose, a second dose of 1 g of tranexamic acid or placebo could be given. Patients were assigned by selection of a numbered treatment pack from a box containing eight numbered packs that were identical apart from the pack number. Participants, care givers, and those assessing outcomes were masked to allocation. We originally planned to enrol 15 000 women with a composite primary endpoint of death from all-causes or hysterectomy within 42 days of giving birth. However, during the trial it became apparent that the decision to conduct a hysterectomy was often made at the same time as randomisation. Although tranexamic acid could influence the risk of death in these cases, it could not affect the risk of hysterectomy. We therefore increased the sample size from 15 000 to 20 000 women in order to estimate the effect of tranexamic acid on the risk of death from post-partum haemorrhage. All analyses were done on an intention-to-treat basis. This trial is registered with ISRCTN76912190 (Dec 8, 2008); ClinicalTrials.gov, number NCT00872469; and PACTR201007000192283. Findings Between March, 2010, and April, 2016, 20 060 women were enrolled and randomly assigned to receive tranexamic acid (n=10 051) or placebo (n=10 009), of whom 10 036 and 9985, respectively, were included in the analysis. Death due to bleeding was significantly reduced in women given tranexamic acid (155 [1·5%] of 10 036 patients vs 191 [1·9%] of 9985 in the placebo group, risk ratio [RR] 0·81, 95% CI 0·65–1·00; p=0·045), especially in women given treatment within 3 h of giving birth (89 [1·2%] in the tranexamic acid group vs 127 [1·7%] in the placebo group, RR 0·69, 95% CI 0·52–0·91; p=0·008). All other causes of death did not differ significantly by group. Hysterectomy was not reduced with tranexamic acid (358 [3·6%] patients in the tranexamic acid group vs 351 [3·5%] in the placebo group, RR 1·02, 95% CI 0·88–1·07; p=0·84). The composite primary endpoint of death from all causes or hysterectomy was not reduced with tranexamic acid (534 [5·3%] deaths or hysterectomies in the tranexamic acid group vs 546 [5·5%] in the placebo group, RR 0·97, 95% CI 0·87-1·09; p=0·65). Adverse events (including thromboembolic events) did not differ significantly in the tranexamic acid versus placebo group. Interpretation Tranexamic acid reduces death due to bleeding in women with post-partum haemorrhage with no adverse effects. When used as a treatment for postpartum haemorrhage, tranexamic acid should be given as soon as possible after bleeding onset. Funding London School of Hygiene & Tropical Medicine, Pfizer, UK Department of Health, Wellcome Trust, and Bill & Melinda Gates Foundation