861 research outputs found
The microscopic origin of thermal cracking in rocks: An investigation by simultaneous time-of-flight neutron diffraction and acoustic emission monitoring
We demonstrate that neutron diffraction measurements make it possible to quantify elastic strains within the interior of solid samples, and thus have great potential for addressing a wide range of problems connected with the characterization of the mechanical properties of geological materials. We use the time-of-flight neutron diffraction technique, in combination with acoustic emission monitoring, to study the evolution of thermal strain within the interior of samples of a pure quartzite during slow heating, and the onset of the associated thermal cracking. Thermal cracking commences around 180 degreesC when the thermal strain deficit along the a-axes of quartz grains induces a thermal stress that is close to the bulk tensile strength of the rock
Global Care of Orphaned and Vulnerable Children
Care for orphaned and vulnerable children living in poverty is a widespread concern affecting millions worldwide. This presentation will focus on the current literature surrounding physical, emotional and environmental care in the following countries: Mozambique, the USA and the Philippines. There is a correlation among these three countries involving the lack of food, health care and education. There will be an emphasis on the national policies implemented within each country that seek to ensure sustainability and quality in care. This presentation will also focus on the positive change that is being fulfilled by both government and non-government organizations passionate about the issue in each specific country. Some of these agencies include Naomi’s Heart Mission, The Creche and Local Organizations in Ohio
Reactive Ion Etch (RIE) of Silicon and ZEP520A Resist Mask with Tetrafluoromethane (CF4) Using Oxford 80 Plus
This report discusses the results of etching silicon with electron beam lithography defined features in ZEP520A resist using CF4 in the Oxford 80 Plus RIE
Hydropyrolysis: implications for radiocarbon pre-treatment and characterization of Black Carbon
Charcoal is the result of natural and anthropogenic burning events, when biomass is exposed to elevated temperatures under conditions of restricted oxygen. This process produces a range of materials, collectively
known as pyrogenic carbon, the most inert fraction of which is known as Black Carbon (BC). BC degrades extremely slowly, and is resistant to diagenetic alteration involving the addition of exogenous carbon making it a useful target substance for radiocarbon dating particularly of more ancient samples, where contamination issues are critical. We present results of tests using a new method for the quantification and isolation of BC, known as hydropyrolysis (hypy). Results show controlled reductive removal of non-BC organic components in charcoal samples, including lignocellulosic and humic material. The process is reproducible and rapid, making hypy a promising new approach not only for isolation of purified BC for 14C measurement but also in quantification of different labile and resistant sample C fractions
School Counselors\u27 Experiences Working with Digital Natives: A Qualitative Study
To better understand school counselors\u27 experiences related to students\u27 use of social media, the authors conducted a qualitative study, utilizing a phenomenological approach, with eight practicing high school counselors. Three major themes emerged from the study: “the digital cultural divide,” “frustration and fear,” and “embracing change.” This article presents implications for school counseling practice and research
On the static and dynamic properties of flax and Cordenka epoxy composites
Fibre reinforced composites have excellent specific properties and are widely sought after by engineers seeking to reduce mass. However, end of life disposal is a significant problem and so research into more sustainable natural fibre composites is extremely topical. This paper examines the applicability of natural fibre composites for high performance structural applications. Woven flax and regenerated cellulose (Cordenka) textiles were pre-impregnated with commercially available epoxy resins and consolidated into test laminates in an autoclave to determine their static (compressive, tensile, flexural) and dynamic (energy absorption) properties.
The range of compressive strengths was 77.5–299.6 MPa. Tensile strengths ranged from 63 to 92.6 MPa and interlaminar shear strength (ILSS) from 10.7 to 23.3 MPa. Specific energy absorption (SEA) varied between 21.2–34.2 kJ/kg. Biotex flax combined with MTM49 resin matched the SEA of T300 carbon fibre using the same resin system and layup. This work has demonstrated that natural fibre composites have significant scope for use in structural applications but additional work is required on fibre to matrix bonding in order to maximise their properties whilst remaining an environmentally credible option
A person-centered approach to understanding negative reinforcement drinking among first year college students [post-print]
The current study used a person-centered approach (i.e. latent profile analysis) to identify distinct types of college student drinkers based on the predictions of motivational, social learning, and stress and coping theories of maladaptive drinking. A large sample (N = 844; 53% female) of first-year undergraduates from two institutions, public and private, who reported consuming one or more drinks in the last three months completed measures of depressive and anxiety symptoms, positive alcohol-outcome expectancies, negative life events, social support, drinking motives, drinking level and drinking-related problems. Latent profile analysis revealed a small subgroup of individuals (n = 81, 9%) who conformed to the anticipated high-risk profile; specifically, this group demonstrated high levels of negative affect, coping motives, drinks per week, and drinking-related problems. However, additional groups emerged that showed patterns inconsistent with the proposed vulnerability profile (e.g., high negative affect, positive expectancies, and negative life events, but relatively low drinking levels). Findings from our person-centered approach showing the presence of groups both consistent and inconsistent with the predictions of motivational, social learning, and stress and coping theories highlight the need to identify and target certain college students for prevention and intervention of negative affect-related drinking
- …