Crack coalescence and strain accommodation in gypsum rock

Gypsum is a soft rock with low strength and high propensity to plastic deformation. Its mechanical properties are relevant in a wide range of technical application (e.g. tunnel excavation, stability assessment of underground quarries, oil and gas accumulation). The micro-mechanisms involved in the deformation of gypsum rock have for long time interested the scientific world and are still not completely understood. The peculiar crystallographic structure of this bi-hydrate salt, with water molecules layered in the salt structure, favours the development of plastic structures in the rock.  The present work proposes an experimental investigation of strain accommodation mechanisms in gypsum rock, reporting data referred to uniaxial and triaxial stress conditions. The rock strain was studied with a multiscale approach, with the comparison of results from DIC and microstructural analyses

An intracooling system for a novel two-stage sliding-vane air compressor

Lube-oil injection is used in positive-displacement compressors and, among them, in sliding-vane machines to guarantee the correct lubrication of the moving parts and as sealing to prevent air leakage. Furthermore, lube-oil injection allows to exploit lubricant also as thermal ballast with a great thermal capacity to minimize the temperature increase during the compression. This study presents the design of a two-stage sliding-vane rotary compressor in which the air cooling is operated by high-pressure cold oil injection into a connection duct between the two stages. The heat exchange between the atomized oil jet and the air results in a decrease of the air temperature before the second stage, improving the overall system efficiency. This cooling system is named here intracooling, as opposed to intercooling. The oil injection is realized via pressure-swirl nozzles, both within the compressors and inside the intracooling duct. The design of the two-stage sliding-vane compressor is accomplished by way of a lumped parameter model. The model predicts an input power reduction as large as 10% for intercooled and intracooled two-stage compressors, the latter being slightly better, with respect to a conventional single-stage compressor for compressed air applications. An experimental campaign is conducted on a first prototype that comprises the low-pressure compressor and the intracooling duct, indicating that a significant temperature reduction is achieved in the duct

A Comparison of Marketing Techniques Among Military Recruiters

The U.S. Department of Defense spent $11 billion in enlistment and retention bonuses from 2006 to 2010, which had only a marginally positive effect on the enlistment rate for the Army. The case study addressed this business problem of recruiting by exploring marketing strategies successful recruiting professionals used to motivate individuals to join the military. The purpose of this study was to determine effective recruiting strategies. Therefore, it incorporated the conceptual framework of emergent strategy theory, which postulated the best strategies are neither completely planned nor completely random, but are rather an adaptation to changing dynamics and circumstances. The population consisted of 2 former recruiters, 1 from the Army and another from the Marine Corps, as well as 38 college students located in Wilkes-Barre, Pennsylvania. Data for the study morphed from face-to-face interviews and 3 focus groups comprised of 10 to 15 students each, for the purpose of addressing the research question. Data analysis occurred through a process of coding and theming. The 9 themes identified included tell the story, advertising strategies, and fit for duty. A lesson learned from these themes was that the key for successful recruiting strategies lies in aligning with the wants and needs of individuals in the target demographic. If senior leaders in the Department of Defense followed the recommendations provided, each of the branches of the military service could potentially achieve higher recruiting rates at a lower cost. The study could result in social change whereby eligible recruits could view the Army and Marine Corps as professions of arms in which individuals can live out their ideals of patriotism but also have a good quality of life due to the benefits of military service

A microcapillary rheometer for microliter sized polymer characterization

Abstract We report the design of a microcapillary rheometer (μCR) that allows to perform experiments rapidly and in a broad range of shear rates (i.e., from 0.1 to 1000 s−1), using small amounts of material (i.e., just few milligrams). Additionally, multiple measurement parallelization makes it suitable for High-Throughput Rheological Experimentation of polymer melts (HT-Rheo-E). The novel rheometer consists of a set of three cylindrical microcapillaries in which the fluid flows driven by a controlled pressure. A camera, placed at the capillary exit, records the fluid motion to measure its flow rate, from which the fluid viscosity can be determined. The optimization of the setup allowed for reliable and fast viscosity measurements using ca. 10 mg of material. The current work reports the design of the rheometer and validation measurements on several model fluids. The microfabricated μCR is of potential interest for applications in quality control and research where rapid and repeated measurements using limited milligrams of polymer are required, as well as for High-Throughput-Experimentation of complex fluids (e.g., biological systems)

Atomistic Simulation of La and Mn-Doped PbBi2Nb2O9 Aurivillius Phase

This study aims to determine the effect of Mn3+ and La3+ dopants on the structure of PbBi2Nb2O9 (PBN) using atomistic simulation. PBN phase geometry was optimized before the Mn3+ and La3+-doped phase. Mn3+ partially substituted octahedral Nb5+ in the perovskite layer. While La3+partially substituted Bi3+ in the bismuth layer and dodecahedral Pb2+in the perovskite layer. The concentration (x) of dopants that doped PBN was made in such a way that it produces a phase of Pb1-2xBi1.5 + 2xLa0.5Nb2-xMnxO9 (x = 0, 0.1, and 0.3) which was not charged. The simulation results showed that the optimized PBN cell parameters were in a good agreement with the experimental result. Increasing the concentration of dopants result in the Pb1-2xBi1.5+ 2xLa0.5Nb2-xMnxO9 phase (PBNM-Bi and PBNM-A) being less stable, as indicated by the increased lattice energy. PBNLM-Bi structures experiences an elongation which was showed by the cell parameters of c increase while a and b decrease. La3+prefers to occupy bismuth oxide layer rather than the dodecahedral A-site of the perovskite layer. The results of this simulation can explain the PBLNM structure of experimental results that do not pay attention to the multiplicity of doped PBN with certain dopant concentrations

Migration and determinants of health : clinical epidemiological characteristics of migrants in Malta (2010-11)

Background Over recent years Malta has experienced a growing influx of migrants from Africa. With the aim of defining demographic characteristics and assessing the prevalence of conditions of public health significance among asylum seekers in Malta, a clinical research study was implemented in the framework of the European Union project ‘Mare nostrum’. Methods From August 2010 to June 2011 a dermatologist and an infectious diseases specialist performed general and specialist health assessment of migrants hosted in open centres. Results Migrants included in the study were 2216, 82.7% were males, their mean age was 25 years and 70.1% were from Somalia. Out of the total females, 42.5% had undergone some type of Female Genital Mutilation/Cutting. A total of 5077 diagnoses were set, most common were skin diseases (21.9%), respiratory diseases (19.8%) and gastro-enteric diseases (14.2%), whereas 31% of migrants reported good health conditions. Conclusions Immigrants have a lower morbidity burden compared with their fellow countrymen living in the origin country. However, living conditions during the journey, in transit countries and after arrival can influence their health status. The present study provides a comprehensive picture of this growing population that is in need for health promotion, mental health services and fair policy planning.peer-reviewe

Synthesis of novel cognition enhancer with pyrazolo[5,1-c][1,2,4]benzotriazine core acting at gamma-aminobutyric acid type A (GABAA) receptor.

Memory dysfunction associated with aging, neurodegenerative and psychiatric disorders represents an increasing medical need. Advances in research exploring the biological mechanisms underlying learning and memory have opened new potential approaches for development of memory-enhancing therapies addressed to selective neuronal targets. In this work, we synthesized some derivatives with a pyrazolo[5,1-c][1,2,4]benzotriazine core to identify ligands on GABA A receptors subtype (benzodiazepine site on GABAA- receptor) endowed with the potential of enhancing cognition activity without the side effects usually associated with non-selective GABAA modulators. In fact, there is much evidence that GABAA-R (γ-aminobutyric acid, type A receptor) subtype ligands have relevance in learning and memory. In vitro and in vivo tests have been performed. Pharmacological data indicate that compounds 7, 13, 14 and 22 act as dual functional modulators of GABA A-Rs (promnemonic and anxiolytic agents) while only compounds 3 and 10 stand out as selectively displaying good antiamnesic and procognitive activity (1 and 3 mg/kg, respectively). © 2013 Elsevier Ltd. All rights reserved