bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface Effects on the Magnetic Behavior of Nanocrystalline Nickel Ferrites: The Effect of Surface Roughness and Dilution
Authors: Nathani H. , Misra R.D.K. , Egelhoff W.F.
Published: June 2019

The paper describes the surface roughness and dilution effects on the magnetic behavior of nanocrystalline nickel ferrites studied by SQUID magnetometer. Two different kinds of measurements were performed: (a) zero-field cooling (ZFC) and field cooling (FC) magnetization versus temperature and (b) magnetization as a function of the applied field. The analysis of magnetic measurements indicate that while the superparamagnetic behavior is retained by nanocrystalline ferrites of different surface roughness (0.8-1.8 nm) at 300K, the hysteresis loop at 2K becomes non-squared and the coercivity increases with increase in surface roughness. This behavior is discussed in terms of broken bonds and degree of surface spin disorder. In diluted dispersion systems containing 10-40% nickel ferrite in a polyethylene matrix, the interparticle attractions continue to be dominant even when the concentration of nickel ferrite is 10 wt.% in the diluted system. The general magnetic behavior of diluted dispersion system is similar to the undiluted system; however, coercivity, remanence, and saturation magnetization are altered. These changes in the magnetic data are ascribed to magnetization interactions that encourage flux closure configuration.
DNA Separation Using Gold/Magnetic Iron-oxide Composite Nanoparticles
Authors: Kinoshita Takuya , Seino Satoshi , Otome Yohei , Mizukoshi Yoshiteru , Nakagawa Takashi , Nakayama Tadachika , Sekino Tohru , Niihara Koichi , Yamamoto Takao A.
Published: June 2019

Amounts of oligonucleotides adsorbed onto the Au/γ-Fe2O3 composite nanoparticles synthesized by gamma-ray irradiation and picked up by a magnet were evaluated using fluorescence technique. The adsorbing capacity of the oligonucleotides on our nanoparticles are larger than a commercial magnetic beads for a separation of biomolecules.
Autogenerated Air Bubbles for the Spontaneous Formation of Nanostructures
Authors: Yoon Seok Min , Choi Hee Cheul
Published: June 2019

In this paper, a novel mild synthetic route was tentatively designed to achieve both shape and dimension-defined nanostructure such as nanorods, nanowires and nanocircles which were fully characterized by AFM and TEM. Bubbles, which are automatically generated when water is mixed with ethanol by a simple shaking, act as a nanoreactor to produce these nanostructures. Fe containing nanowire, nanorod and nanocircle are successfully prepared by using this method. Autogenerated bubble-mediated formation of nanostructures has advantages over conventional methods in terms of short reaction time, low energy consumption and absence of complicated experimental equipments.
Synthesis of GaS Nanoparticles from a Single-Source Precursor [Ga(S2CNEt2)3/
Authors: Malik Mohammad Azad , O'Brien Paul , Mlondo Sibusiso N. , Revaprasadu Neerish
Published: June 2019

GaS nanoparticles have been synthesized by thermolysis of [Ga(S2CNEt2)3] in 4- ethylpyridine. Their absorption spectrum give a band edge at 440 nm (band gap,3.0 eV). XRD pattern showed abroad peaks corresponding to cubic phase of GaS. TEM images confirmed the crystalline nature of particles with narrow size distribution (5.4 nm ± 0.7 dia). To our knowledge this the first time that GaS nanoparticles have been prepared.
Self-Peeling of Porous Nickel Foam from the Electrochemically Etched Porous Silicon
Authors: Zhang Xi , Tu King-Ning
Published: June 2019

A low-doped p-type silicon wafer was wet-etched to form macropores in a high-aspect-ratio, straight and parallel manner along the Si (100) direction. It was then plated in aqueous alkaline solution containing Ni2+. Metallic Ni was rapidly deposited in the macropores on the sidewall surface without using a reducing agent or activation treatment at slightly elevated temperature. After being immersed for certain duration, the single crystalline Si of sidewalls was replaced by polycrystalline Ni while the initial porous structure was still maintained. When Ni became dominant in the entire porous regime, the porous film more than 200 μm thick was discovered to be able to peel off very easily from the Si substrate beneath. In this way, a piece of nickel foam with straight pores of very high aspect ratio is self-formed and self-peeled.
In-Situ Tem Study of Interface Sliding and Migration in an Ultrafine Lamellar Structure
Authors: Hsiung Luke L.M. , Nieh T.G.
Published: June 2019

The stability of interfaces in an ultrafine TiAl-(y)/Ti3Al-(α2) lamellar structure by straining at room temperature has been investigated using in-situ straining techniques performed in a transmission electron microscope. The purpose of this study is to obtain experimental evidence to support the previously proposed creep mechanisms in ultrafine lamellar TiAl alloys based upon the interface sliding in association with a cooperative movement of interfacial dislocations. The results have revealed that both the sliding and migration of lamellar interfaces can take place simultaneously as a result of the cooperative motion of interfacial dislocations.
Properties of Nanoscaled Multiphase Structures and Non-Equilibrium Solid Solutions Obtained by Severe Plastic Deformation [Abstract + Supplemental Data]
Authors: Sauvage Xavier , Quelennec Xavier , Jessner Peter , Wetscher Florian , Pippan Reinhard
Published: June 2019

Grain size reduction induced by severe plastic deformation (SPD) and the resulting mechanical properties have been widely investigated for pure metals but less is known and reported about multi-phase materials. To study the grain size reduction mechanisms in multiphase structure subjected to SPD, two copper based composites (Cu-10%Fe and Cu-43%Cr) were severely deformed by torsion under high pressure. The grain size achieved with these composite materials is much smaller than in pure metals. It is for example in a range of 10 to 20 nm for the Cu-43%Cr composite, e.g. one order of magnitude lower than in pure Cu processed by SPD. Three dimensional atom probe data show also the formation of non equilibrium supersaturated solid solutions. The mechanisms of the deformation induced intermixing are discussed together with its influence on the mechanical properties.
Mechanical Properties of Ni-P/Diamond Composite Films Processed by Electro-less Plating Method
Authors: Cho Jin Ki , Yoo Mi Sun , Kim Moon Tea , Beak Seung Roung , Kang Sung Goon , Kang Chan Hyoung
Published: June 2019

In this investigation, we carried out an experiment on the process and properties of Ni-P/Nano-Diamond(ND) composite coating with plating conditions.The particle size of nano diamond(ND) by electric explosion method was about 3-8nm size, but these were very easily agglomerated due to high surface energy of ND particles.The ND particles agglomerate diameter (min) were successfully dispersed by ultrasonic dispersion method, after the 400W, 24kHz , 30min ultrasonic treatment.The best dispersibility of ND powder suspension was obtained when the NDconcentration was loaded 1g/l, and ultrasonic dispersion time was 30min, and pH 5. The experimental results revealed that ND composite platings had the remarkable differences such as surface roughness, morphology and friction coefficient compared to conventional diamond-free electroless Ni-P plating.The best mechanical properties were obtained when the concentration of ND powder was 1g/l and the ultrasonic treatment time was 30min and pH of the plating solution was 5.From these results, we were confirmed that the ND particles were uniformly co-deposited in the Ni-matrix when electroless Ni-P/ND composite plating was deposited by the best plating conditions.
Residual Stress Distribution, Intermolecular Force, And Frictional Coefficient Maps In Diamond Films: Processing-Structure-Mechanical Property Relationship
Authors: Gupta Sanju , Williams Oliver , Patel R. J. , Bohannan E. , May P. W.
Published: June 2019

Carbon in its various forms, specifically nanocrystalline diamond, may become a key material for the manufacturing of micro- and nano-electromechanical (M/NEMS) devices in the 21st Century. In order to utilize effectively these materials for M/NEMS applications, understanding of their microscopic structure and physical (mechanical properties, in particular) become indispensable. The micro- and nanocrystalline diamond films were grown using hot-filament and microwave chemical vapor deposition techniques involving novel CH4 / [TMB for boron doping and H2S for sulfur incorporation] in high hydrogen dilution chemistry. To investigate residual stress distribution and intermolecular forces at nanoscale, the films were characterized using Raman spectroscopy and atomic force microscopy in terms of topography, force curves and force volume imaging. Traditional force curve measures the force felt by the tip as it approaches and retracts from a point on the sample surface, while force volume is an array of force curves over an extended range of sample area. Moreover, detailed microscale structural studies are able to demonstrate that the carbon bonding configuration (sp2 versus sp3 hybridization) and surface chemical termination in both the un-doped and doped diamond have a strong effect on nanoscale intermolecular forces. The preliminary information in the force volume measurement was decoupled from topographic data to offer new insights into the materials's
Optical Coating Properties for Enhanced Blown-Sand Abrasion Resistance
Authors: Drew Christopher , Bosselman Suzanne , Ziegler David
Published: June 2019

Lenses and other transparent optical materials suffer rapid damage when subjected to blowing abrasive particulates. The time-scale of these impact event falls between typical scratch tests (less than 1m/s) and ballistic tests (100s of m/s) and has not been studied in depth to date. Polymeric lens materials like polycarbonate are usually treated with a scratch-resistant coating, which is commonly silica-based. The coating provides some protection, yet is not sufficient at resisting abrasion from blown sand in most commercial products. We demonstrate that silicone elastomeric coatings are superior to polycarbonate and silica glass at resisting damage by blown sand particles. Sand abrasion tests were conducted using a custom-built test apparatus that exposes the sample to 400 micron diameter quartz silica moving at 16.5 m/s (approx. 38 mph). Scanning electron microscopy revealed the presence of small cracks and pits in polycarbonate, coated polycarbonate, and silica glass after sand exposure. No such damage was observed in the silicone-coated samples after an identical exposure.

We speculate that the elastic tensile strain at the surface is an important predictor of the material response at the time-scale of the impact. A simple mathematical model was developed using a momentum balance pre- and post-impact, and was used to approximate the maximum deformation and impact time-scale. A semispherical interaction volume was used in the model with a radius of 1.5x the particle diameter, determined through profilometry experiments. The material’s resistance to deformation was measured experimentally through a static mechanical test using a spherical indenter to represent the particle. Tensile tests were performed on both materials to identify the maximum elastic strain.Additionally, dynamic mechanical tests were performed to confirm that the mechanical behavior at long time-scales was valid at shorter time-scales of the impacts. DMA curves were shifted using the WLF equation. Profilometry and scanning electron microscopy (SEM) imaging were used to confirm the presence or absence of blown-sand induced damage.
Protection of Glass from Scratches: The Use of a Hard, Thin Coating to Minimize Damage
Authors: Tartivel Ronan , Reynaud Emmanuelle , Grasset Fabien , Sangleboeuf Jean-Christophe , Rouxel Tanguy
Published: June 2019

Used throughout human history, glass has recently been reconsidered as a major structural material as shown by the large window surfaces in use nowadays in vehicles and buildings. Its transparency hides a significant mechanical drawback, however: Brittleness, which arises from surface flaws. In times where reducing the weight and increasing the lifetime of structures is a growing concern, any strategy to increase the toughness of glass is of interest.

Our study aims at coating glass surfaces with a hard, thin, transparent protective layer in order to minimize the density of surface flaws. A reverse micro-emulsion synthesis was used to produce a dispersion of colloidal silica nanoparticles (∼30 nm in diameter) which were then deposited on a glass substrate by dip-coating. Thermal treatment was then used to remove any organic components, leading to the production of mono- and bilayer structures as observed via atomic force microscopy (AFM). Microindentation experiments revealed a lower elastic modulus in the coating versus the substrate, in spite of its fully inorganic nature. Scratch tests were then performed at increasing applied load using a custom-built sclerometer. The coating was found to delay the appearance of visually apparent scratches by reducing the degree of chipping observed during scratch development. Instead, such coatings exhibit a transition from ductile behavior directly to the abrasive regime classically observed in glass at high loads, avoiding the production of extended sub-surface cracks that normally give rise to visual damage.
Mechanical Characterization of Thin-Film Composites using the Load-Deflection Response of Multilayer Membranes - Elastic and Fracture Properties
Authors: Gaspar Joao , Ruther Patrick , Paul Oliver
Published: June 2019

This paper reports on the refinement of a mechanical model for the load-deflection of multilayer membranes under uniform differential pressure and on its application to the experimental extraction of material parameters. Going beyond previous results, the analytical model takes into account the mechanics of multilayers and elastic supports covering all cases between rigidly clamped to simply supported structures and enables the straightforward assessment of stress profiles within the deformed structures. A comprehensive set of long membranes made of various multilayers of silicon nitride and oxide films are fabricated and characterized. The out-of-plane deflection profile under pressure load is monitored by means of a laser profilometer. The pressure is stepped up until fracture occurs. From the stress profiles in the membrane at fracture, the brittle material strength is analyzed using Weibull statistics. The bulge setup has been fully automated for the measurement of 80 membranes per wafer. This realizes, for the first time, the high throughput-acquisition of mechanical thin film data with convincing statistical control.
Optimizing Nonlinear Properties of Thermal Sprayed Coatings through Processing Parameters
Authors: Liu Yajie , Nakamura Toshio , Srinivasan Vasudevan , Gouldstone Andrew , Sampath Sanjay
Published: June 2019

Low-temperature thermal cycling of plasma sprayed zirconia coatings via curvature measurements is used to quantify their nonlinear mechanical behavior. The nonlinear feature arises from the unique layered, porous and cracked morphology of thermal sprayed ceramic materials. With this procedure, various specimens were tested to investigate the effects of processing condition. The measured nonlinear properties are interpreted in the context of microstructural changes in the plasma sprayed coatings due to differences in particle state upon impact and coating build-up. The implications of this study are significant for thermo-mechanical design of strain-tolerant ceramic coatings in thermal barrier applications.
Foaming of Miscible and Immiscible Polymer Blends
Authors: Ruckdaeschel Holger , Rausch Julius , Sandler Jan K.W. , Altstaedt Volker , Schmalz Holger , Mueller Axel H.E.
Published: June 2019

Batch-foaming of miscible, immiscible and compatibilized polymer blend systems over a wide compositional range was carried out using carbon dioxide as a physical blowing agent. The resulting foam morphology was characterized by a detailed evaluation of foam density as well as of the cellular parameters. With regard to multiphase blends, transmission electron microscopic observations further provided a detailed insight into the cell wall morphology. The role of the melt-elongational properties and of the glass transition behavior of the various blend systems on the foaming characteristics was systematically elucidated. While the miscible blends showed a simple additivity behavior with regard to their foaming characteristics and properties, a significant influence of the initial blend morphology is demonstrated for the multiphase blends.
Interface Conditions for Coupled Atomistic and Continuum Models of Solids for Dynamics Problems at Finite Temperature
Authors: Li Xiantao , E Weinan
Published: June 2019

We will present a general formalism for deriving boundary conditions for molecular dynamics simulations of crystalline solids in the context of atomistic/continuum coupling. These boundary conditions are modeled by generalized Langevin equations, derived from Mori-Zwanzig's formalism. Such boundary conditions are useful in suppressing phonon reflections, and maintaining the system temperature.
Multiscale Modeling of Frictional Behavior of Highly-Ordered Carbon Nanotube/Ceramic Nanocomposites
Authors: Xia Zhenhai , Curtin William A , Guduru Pradeep
Published: June 2019

Micromechanics model incorporating with molecular dynamics (MD) simulation is developed to simulate the frictional behavior of carbon nanotube (CNT) arrays in ceramic nanocomposites. MD model is used to compute the interaction force and simulate failure mechanisms of individual nanotube at atomic length scale. The force and deformation calculated from MD simulation are passed to the continuum model to simulate the interaction between nanotube arrays and AFM tips. The coefficient of friction is determined at different load levels. The simulation shows that the low friction in the thick-wall CNT systems occurs because the stiffer CNTs are more resistant to collapse under the applied loads. The predictions for the coefficient of friction are consistent with nanoscale tests.
Synthesis and Characterization of Nitrides of Iridium and Palladium
Authors: Crowhurst Jonathan , Goncharov Alexander , Sadigh Babak , Zaug Joseph , Meng Yue , Prakapenka Vitali
Published: June 2019

We describe the synthesis of nitrides of iridium and palladium using the laser-heated diamond anvil cell. We have used the in-situ techniques of x-ray powder diffraction and Raman scattering to characterize these compounds and have compared our experimental findings where possible to the results of first-principles theoretical calculations. We suggest that palladium nitride is isostructural with pyrite while iridium nitride has a monoclinic symmetry and may be isostructural with baddeleyite.
Tape Casting Technique for Fabrication of Graded-Density Impactors for Tailored Dynamic Compression
Authors: Martin L. Peter , Nguyen Jeffrey H. , Patterson Jeremy R. , Orlikowski Daniel , Asoka-Kumar Palakkal P. , Holmes Neil C.
Published: June 2019

Recently, the use of graded density impactors for dynamic compression experiments has received increasing interest. These gas gun experiments have demonstrated complex loading paths which can last microseconds, and may be capable of bridging the timescales of existing static and dynamic compression experiments. A tape casting technique has been developed for fabrication of the impactors. In the technique, a series of tapes were prepared in the Mg-Cu system with compositions ranging from 100% Mg to 100% Cu. The tapes were characterized for their layer thickness, density, and sound wave velocity. Impactors were fabricated by punching individual layers from the tapes, stacking and laminating them, removing the organic matrix, and hot-pressing the laminated structure. The density profile is determined by the order in which the tapes are stacked in the laminate and is therefore highly flexible. The resultant thickness and average density of the impactors is consistent with the data for the individual layers. Impactors were characterized for uniformity by ultrasonic C-scan and white light interferometry. Dynamic compression experiments were performed on a two-stage helium gas gun using the graded density impactors. Results will be presented and shown to agree well with hydrocode modeling.
High Pressure and High Temperature Induced Polymeric C60 Nanorods and Their Photoluminescence Properties
Authors: Liu Bingbing , Hou Yuanyuan , Wang Lin , Zou Guangtian , Iwasiewicz Agnieszka , Sundqvist Bertil
Published: June 2019

We report that C60 nanorods of three polymeric phases have been synthesized under high pressure and high temperature and that the photoluminescence properties of these polymeric nanorods also have been studied. C60 nanorods were fabricated by a facile solution evaporation method. Raman spectra indicate that this material transformed into orthorhombic, tetragonal and rhombohedral polymeric phases under various high pressure and high temperature conditions. SEM measurements show that the shape of the nanorods can be kept under quasi-hydrostatic pressure condition. The photoluminescence intensity of the polymeric C60 nanorods has been enhanced compared with that of the pristine C60 nanorods. The main fluorescence band shifted from 1.70 eV in the monomeric phase to near infrared in the polymeric phase when pressure and temperature were increased. The enhanced fluorescence with adjustable frequency for different polymeric C60 nanorods makes possible potential application in luminescent nanomaterials.
Pressure Dependence of Electron Density Distribution of Ferroielectric KNbO3 Polymorphs by Maximum Entropy Method (MEM) Using Single Crystal Diffraction Study
Authors: Yamanaka Takamitsu , Okada Taku , Nakamoto Yuki , Ohi Kenji
Published: June 2019

Single-crystal structure analysis of KNbO3 has been executed under high pressure through diamond anvil cell installed in the four-circle diffractometer using synchrotron radiation at Photon Factory, KEK in order to clarify the dielectric property. KNbO3 has three structural transitions with increasing pressure at ambient temperature: from orthorhombic structure with the space group Cm2m (Amm2) to tetragonal structure (P4mm) at about 7.0 GPa, to cubic structure (Pm3m) at about 10.0 GPa. The highest-pressure cubic phase is paraelectric, and the other two phases are ferroelectric. The dielectric changes in KNbO3 are clarified by the successive pressure-change of the electron density distribution observed by maximum entropy method (MEM) using high-pressure diffraction data. The MEM electron density maps suggest that the tetragonal phase designates the largest polarization among three polymorphs. The maps also indicate that the localization of the valence electron around the cation position is more enhanced under higher pressure.
IRIDESCENCE OF VIOLET WOODHOOPOE MANTLE FEATHERS
Authors: Cooper Mark , Sewell Brian , Jaffer Mohamed
Published: June 2019

Mantle feathers of Namibian Violet Woodhoopoe Phoeniculus  damarensis were examined by light and transmission electron microscopy. Iridescence of violet barbules and their biological basis were figured and discussed.
Bird Distribution Dynamics - African black oystercatcher in South Africa
Authors: Lerm Rion Elias , Underhill Les G
Published: June 2019

This is another paper on bird distribution dynamics in Biodiversity Observations. The objective of this series of papers is to report on the ranges of bird species as revealed by the Second Southern African Bird Atlas Project (SABAP2, 2007 onwards) and to describe how their ranges have changed since the first bird atlas (SABAP1, mainly 1987 /- 1991), about two decades apart. The African Black Oystercatcher Haemetopus moquini is neither considered a Red-listed species globally nor regionally however, this endemic and iconic bird was expected to decline due to a variety of anthropogenic and natural influences hence, it received much attention from the scientific community. SABAP data supported the findings of some previous projects that looked at both oytsercacther distribution, dispersion and feeding ecology along South Africa's (SA) coastline as well as that of the alien Mediterranean Mussel Mytilus galloprovincialis. Possible reasons for a relatively recent and northern presence along the SA coastline could be due to southern populations experiencing food shortages during the breeding season that result in seasonal dispersion or carrying capacity on the mainland has been reached. Inside the /oystercatcher's breeding range, the alien mussel serves as an additional food source that probably explains the largest SABAP2 reporting rates along the southern regions of the coastline as this area coincides with the /mussel's distribution range.
Addressing medical students with psychodynamic education
Authors: Rueckert Kamiar Kersten
Published: June 2019

This article was migrated. The article was not marked as recommended. Mental symptoms rank high among medical students and residents. Roughly one fourth of the student body is affected. This widespread presence may influence the core of our profession: Emotions. Medical students who tend to suppress their negative emotions display a higher prevalence of depressive symptoms, anxiety and distress. The patients' symptom onset is often linked to a specific time of personal significance. Patients regularly offer a relationship by pointing towards psychosocial issues. The students' suppression of negative emotions may lead to a neglect of topics connected to these emotions during history taking. This leads to an abandonment of the biopsychosocial model of health and inhibits the growth of a doctor-patient relationship. We need preventive measures to decrease the high prevalence of mental symptoms and improve our patient's health. Mandatory classes on patients' psychosocial clues and students' emotional response could improve two crucial points: The reduction of the students' own symptoms and a curious investigation of the patient's entire history. This personal view by a German MD is a pledge for a paradigm shift in the medical curriculum.
Curriculum Goals and Learning Outcomes of Medical Ethics and Professionalism Courses in Undergraduate Medical Curriculum of Pakistan
Authors: Javaeed Arslaan
Published: June 2019

This article was migrated. The article was not marked as recommended. The objective of this paper is to develop curriculum goals and learning outcomes of medical ethics and professionalism courses in undergraduate medical curriculum of Pakistan which is the next step after general needs assessment and targeted needs assessment. The Medical Ethics and Professionalism curriculum has been designed to be implemented at undergraduate level of medical education. The logic model presented in the paper may act as a blueprint for educators developing a Medical Ethics and Professionalism course for teaching guiding principles of practice of medicine to prospective doctors. The logic model highlights the elements e.g. human, financial resources and PMDC's support, impact of short terms and long-term outcomes for learners, educators and patients that should be taken into account at every step of implementation.
The impacts of biodiesel feedstock production systems in South Africa: An application of a Partial Equilibrium Model to the Eastern Cape Social Accounting Matrix
Authors: Adeyemo O. , Wise Russell , Brent Alan
Published: June 2019

In this paper the impacts of biodiesel feedstock production in the Eastern Cape Province of South Africa is assessed through the application of a Partial Equilibrium Model to the Eastern Cape Social Accounting Matrix, using canola production in the Province as an ‘external shock’. Six economic indicators were estimated. The results show that investment in biodiesel production in the Eastern Cape will generate, in 2007 terms, an additional GDP of R18.1 million and 410 employment opportunities per annum, R24.3 million per annum over an assumed lifetime of 20 years in capital formation, R2.1 million additional income generated in low income households, increase in government revenue, and a positive balance of payment. These indicators imply that, given the parameters that are accounted for in a Partial Equilibrium Model, every Rand invested in canola projects in the Eastern Cape will, overall, be of socio-economic advantage to the Province. It is envisaged that further applications of such models may lead to a better understanding of the implications of biofuels in the South African economy, and thereby inform decision- and policy-making in terms of the sustainability of biofuels production systems in general.
Development of a universal DC power supply using solar photovoltaic, utility and battery power sources
Authors: Oni Joe Oladosu , Bolaji Bukola Olalekan
Published: June 2019

In this paper, a universal direct current (DC) power supply system was developed and tested in order to provide uninterrupted power for DC appliances. The system employs simple Diode OR logic for the three power sources (mains from utility power supply, the solar photovoltaic and battery). The parallel combination of the three diodes at the output functions like a comparator circuit and compares the outputs voltage of the three sources, so that the highest voltage at a particular time feeds the DC output and supplies the charging current to the battery. The universal DC power supply system was tested under various operating conditions and the results obtained showed a good performance of the system. The system outputs, when all the power sources were available, during utility power failure and when only the stored energy in the back-up battery was available were 13.8, 13.1 and 12.2V, respectively. The system guarantees an uninterrupted power supply, which can be used to power telecommunication equipment, audiovisual materials, computers, DC motor driven devices and other DC appliances. A typical day solar radiation varied from 547 W/m2 to 865 W/m2 while the generated voltage from PV varied from 11.8 V to 13.7 V. The generated voltage from solar power source increases with the increase in solar radiation.
Emissions trading as a policy option for greenhouse gas mitigation in South Africa
Authors: Tyler Emily , Du Toit Michelle , Burchell Zelda
Published: June 2019

Emissions trading is fast becoming one of the most popular policy instruments for reducing greenhouse gas emissions internationally. This hybrid instrument combines the certainty of mitigation volume delivered by regulation, whilst also harnessing the power of the market through an economic approach to deliver migitation price discovery and least cost mitigation opportunities. Theoretically, this is a powerful combination.However, the realities of uncertainty and lack of information result in international emissions trading experience deviating substantially from the instrument’s theoretical potential. This is of particular relevance in a developing country context. Scheme design is therefore very important to counter these market failures, and policymakers are required to strike a balance between this and introducing distortions. Given that the instrument is in its infancy, performance of the various schemes up and running internationally is inconclusive. Emissions trading proponents argue that the benefits will be realised over time, once the initial teething problems are overcome. The paper is the result of research conducted in 2008 and presented at the South African Climate Policy Summit in 2009. It considers theory and international experience in application to the potential establishment of an emissions trading scheme in South Africa. Lack of data, capacity and experience with markets in the energy sector present complications in the use of the instrument as a central part of the nation’s mitigation policy suite, as do market concentration issues. Should an emissions trading be proposed, the paper argues for ways in which its design could address these complications, and align with the current energy security imperative resulting from the electricity crisis in the country, the twin political objectives of poverty reduction and employment creation of the recently elected government, and the timeframes proposed by the Long Term Mitigation Scenarios.
What contribution does the installation of solar water heaters make towards the alleviation of energy poverty in South Africa?
Authors: Wlokas Holle Linnea
Published: June 2019

The South African government has publicized plans to install one million solar water heaters in households throughout South Africa by the year 2014, with the goals of reducing strain on existing electricity resources, mitigating greenhouse gas emissions, creating employment and alleviating poverty. This paper examines two existing solar water heater installation projects with the aim of investigating the social contribution of the installation of solar water heaters in low-income households in South Africa. The Sustainable Urban Livelihoods approach (SULA) was adjusted to provide an analytical framework for the development of suitable indicators of social change in the context of renewable energies and energy poverty. Increases in household capital and the reduction of household vulnerability to shocks, stressors and seasonal variability as the result of solar water heater installation were investigated in projects in low-income housing developments in the cities of Cape Town and Port Elizabeth, South Africa.Data collected from paired household surveys (before and after installation) in over 600 households and qualitative information (Most Significant Change stories) show that the provision of a constant, cheap source of heated water contributed positively to the alleviation of energy poverty. Household capitals (categorised as Human, Social, Financial, Physical, Natural and Gender capital), including aspects such as health benefits and time and financial savings, were all positively effected by the installation of solar water heaters. In addition, improved energy security greatly reduced household vulnerability to shocks, stressors and seasonal variability. Comparison between the two projects revealed that the geographical setting (climatic conditions in particular), and the approach and strategies adopted by the implementers of the solar water heater installation project, greatly determine the extent to which benefits to the households are realised.
Performance of A R22 split-air-conditioner when retrofitted with ozone friendly refrigerants (R410A and R417A)
Authors: Bolaji Bukola Olalekan
Published: June 2019

R22 that has been used predominantly in air conditioning and in medium and low-temperature applications contains ozone depleting chlorine atoms and hence will be phased out eventually. This paper presents the experimental performance study of a split-air-conditioner using ozone friendly alternative refrigerants. The existing split-air-conditioner originally designed for R22 as the working fluid was retrofitted with R410A and R417A respectively, and the performance of the system was evaluated and compared with its performance when R22 was used. Experimental results showed that with R417A, the system had 1.9% higher refrigeration capacity and 14.2% lower with R410A when compared to that of R22. The average discharge pressure of the compressor obtained with R417A and R410A were 3.8% lower and 10.3% higher, respectively, than with R22. The lowest compressor power consumption and pressure ratio were obtained with the R417A retrofitted system. The average coefficient of performance (COP) obtained using R417A is 2.9% higher, while that of R410A is 8.4% lower than that of R22. Generally, with R417A the system consistently had the best performance in comparison to both R22 and R410A, indicating that R417A would be a better choice for retrofitting existing split-air-conditioners originally designed to use R22 as working fluid.
Comparisons of Medical Student Knowledge Regarding Life-Threatening CT Images Before and After Clinical Experience
Authors: Nguyen Barbara , Werth Brady , Brewer Nicholas , Ward Jeanette G. , Nold R. Joseph , Haan James M.
Published: June 2019

Introduction. Currently, no national standard exists for educatingmedical students regarding radiography or formal research indicatingthe level of improvement regarding computed tomography(CT) interpretation of medical students during clinical rotations.

Methods. Students were evaluated based on their response totwenty-two open-ended questions regarding diagnosis and treatmentof eleven de-identified CT images of life-threatening injuries.The number of incorrect answers was compared withcorrect or partially correct answers between students startingthird-year clinical rotations and those starting their fourth year.

Results. Survey results were collected from 65 of 65 (100%) beginningthird-year students and 9 of 60 (15%) beginning fourthyearstudents. Students in their fourth-year had less incorrectanswers compared to third-year students, with five questionsreflecting a statistically significant reduction in incorrect responses.The image with the least incorrect for both groups wasepidural hemorrhage, 33.9% and 18.5% incorrect for third-yearstudents for diagnosis and treatment, respectively, and 11.1%and 0% incorrect for fourth-year students. Outside of this image,the range of incorrect answers for third-year students was75.4% to 100% and 44.4% to 100% for fourth-year students.

Conclusion. Baseline CT knowledge of medical students,regardless of clinical experience, indicated a strong deficit,as more students were incorrect than correct for themajority of CT images. KS J Med 2017;10(3):55-58.
A Survey of Safety Recommendations for All-Terrain Vehicle Dealers and Track Owners in Kansas
Authors: Martin Morgan J. , Morton Rychael , Rau Shawn , Nyberg Sue , Berg Gina M.
Published: June 2019

Introduction. All-terrain vehicles (ATVs) are associated with injury,mortality, and healthcare costs. ATV related injuries are less severewhen consistent safety practices are followed, however, ATV safetyregulations are varied among states. This study sought to surveyKansas ATV dealers and track owners to determine safety promotionpractices.

Methods. A cross-sectional telephone survey was conducted ofKansas ATV dealers and tracks. Survey questions included promotionand sale of safety equipment, provision of ATV safety information,and respondent characteristics.

Results. Of those contacted, 32% of dealers and 31% of tracksresponded to the survey. Most ATV dealers sell safety gear (70% -100%) and all recommend safety gear to buyers and riders. All ATVtracks reported requiring helmets (100%) but were varied regardingother forms of safety gear. The majority of ATV dealers (77%) recommendedsafety courses, but only 31% of dealers and 40% of tracksoffered courses. Eighty percent of ATV tracks and 52% of dealers feltthey had a professional responsibility to educate riders/owners onsafety.

Conclusions. Safety promotion by ATV dealers in Kansas consistentlywas recommended, but often limited to the sales of safety gear(helmets and gloves) or the provision of manufacturer provided safetymaterials. Further, ATV dealers reported rarely offering skills tests orsafety courses to buyers. In Kansas, safety promotion at the point ofsale or track level could be improved to increase public awareness ofATV safety practices. KS J Med 2017;10(4):76-78.
Increasing Onshore Oil Production
Authors: Urban Dakota M. , Ward Jeanette G. , Helmer Stephen D. , Cook Alan D. , Haan James M.
Published: June 2019

Introduction. Few data currently exist which are focused on typeand severity of onshore oil extraction-related injuries. The purposeof this study was to evaluate injury patterns among onshore oil fieldoperations.

Methods. A retrospective review was conducted of all traumapatients aged 18 and older with an onshore oil field-related injuryadmitted to an American College of Surgeons-verified level 1 traumacenter between January 1, 2003 and June 30, 2012. Data collectedincluded demographics, injury severity and details, hospital outcomes,and disposition.

Results. A total of 66 patients met inclusion criteria. All patientswere male, of which the majority were Caucasian (81.8%, n = 54)with an average age of 36.5 ± 11.8 years, injury severity score of 9.4 ±8.9, and Glasgow Coma Scale score of 13.8 ± 3.4. Extremity injurieswere the most common (43.9%, n = 29), and most were the resultof being struck by an object (40.9%, n = 27). Approximately onethirdof patients (34.8%, n = 23) were admitted to the intensive careunit. Nine patients (13.6%) required mechanical ventilation while27 (40.9%) underwent operative treatment. The average hospitallength of stay was 5.8 ± 16.6 days, and most patients (78.8%, n = 52)were discharged home. Four patients suffered permanent disabilities,and there were two deaths.

Conclusions. Increased domestic onshore oil production inevitablywill result in higher numbers of oil field-related traumas. By focusingon employees who are at the greatest risk for injuries and by targetingthe main causes of injuries, training programs can lead to a decreasein injury incidence. Kans J Med 2018;11(2):34-37.
Head CT Guidelines Following Concussion Among the Youngest Trauma Patients
Authors: Harvell Bryan J. , Helmer Stephen D. , Ward Jeanette G. , Ablah Elizabeth , Grundmeyer Raymond , Haan James M.
Published: June 2019

Introduction. Recent studies have provided guidelines on the use ofhead computed tomography (CT) scans in pediatric trauma patients.The purpose of this study was to identify the prevalence of theseguidelines among concussed pediatric patients.

Methods. A retrospective review was conducted of patients fouryears or younger with a concussion from blunt trauma. Demographics,head injury characteristics, clinical indicators for head CT scan(severe mechanism, physical exam findings of basilar skull fracture,non-frontal scalp hematoma, Glasgow Coma Scale score, loss ofconsciousness, neurologic deficit, altered mental status, vomiting,headache, amnesia, irritability, behavioral changes, seizures, lethargy),CT results, and hospital course were collected.

Results. One-hundred thirty-three patients (78.2%) received a headCT scan, 7 (5.3%) of which demonstrated fractures and/or bleeds. Allpatients with skull fractures and/or bleeds had at least one clinicalindicator present on arrival. Clinical indicators that were observedmore commonly in patients with positive CT findings than in thosewith negative CT findings included severe mechanism (100% vs.54.8%, respectively, p = 0.020) and signs of a basilar skull fracture(28.6% vs. 0.8%, respectively, p = 0.007). Severe mechanism alonewas found to be sensitive, but not specific, whereas signs of a basilarskull fracture, headache, behavioral changes, and vomiting were specific,but not sensitive. No neurosurgical procedures were necessary,and there were no deaths.

Conclusions. Clinical indicators were present in patients with positiveand negative CT findings. However, severe mechanism of injuryand signs of basilar skull fracture were more common for patients withpositive CT findings. Kans J Med 2018;11(2):38-43.
Evaluation of Protective Equipment Used Among Motorbike Riders
Authors: Stiles Roxanne , Benge Clint , Stiles P.J. , Dong Fanglong , Ward Jeanette , Ablah Elizabeth , Haan James M.
Published: June 2019

Introduction. This study compared outcomes between patientsinjured at a motorbike track, which requires riders to follow safetyequipment guidelines, and those involved in recreational riding wheresafety equipment usage is voluntary.

Methods. A retrospective review was conducted of all patients presentingwith motorbike-related injuries at an American College ofSurgeons verified level-I trauma center between January 1, 2009 andDecember 31, 2013. Data collected included demographics, injurydetails, safety equipment use, hospitalization details, and dischargedisposition. Comparisons were made regarding protective equipmentusage.

Results. Among the 115 patients admitted, more than half (54.8%, n =63) were injured on a motorbike track, and 45.2% (n = 52) were injuredin a recreational setting. The majority of patients were male (93.9%),Caucasian (97.4%), and between the ages of 18 to 54 (64.4%). Helmetusage was higher among track riders (95.2%, n = 60) than recreationalriders (46.2%, n = 24, p < 0.0001). Comparisons of injury severity andoutcomes between those who wore protective equipment and thosewho did not were not significant.

Conclusions. Even though track riders wore protective equipmentmore than recreational riders, there was no difference between thegroups regarding injury severity or hospital outcomes. These resultssuggested that motocross riders should not rely on protective equipmentas the only measure of injury prevention.Kans J Med 2018;11(2):44-47.
The Cost of Routine Follow-Up in Total Joint Arthroplasty and the Influence of These Visits on Treatment Plans
Authors: Hendricks Thomas J. , Chong Alexander C.M. , Cusick Robert P.
Published: June 2019

Introduction. Many physicians recommend annual or biennial visitsafter total hip and knee arthroplasty (THA and TKA). This studysought to establish the cost of a post-operative visit to both the healthcare system and patient and identify if these visits altered patientmanagement.

Methods. A prospective cohort study was conducted using patientspresenting for follow-up after THA or TKA from April throughDecember 2016. All surgeries were performed by a single orthopaedicsurgeon in Wichita, Kansas. All eligible subjects that met the inclusioncriteria received and completed a questionnaire about the personalcost of the visit and their assessment of their function and outcomeafter total joint arthroplasty. The physician also completed a questionnairethat examined the cost of the visit to the health care systemand whether the clinical or radiographic findings altered patient management.

Results. Fifty-six patients participated with an average length of follow-up of 4.5 ± 4.1 years since surgery. The average patient cost was$135.20 ± $190.53 (range, $1.65 - $995.88), and the average visit timefor the patient was 3.9 ± 2.9 hours. Eighty percent of patients reportedno pain during the clinic encounter, and 11% reported loss of function.Eighty-four percent thought the visit was necessary. Physician timefor each visit lasted 12.9 ± 3.7 minutes (range, 10 - 20 minutes). Only9% of patient encounters resulted in an alteration in patient management.This occurred at an average follow-up time of 3.6 ± 1.8 yearsafter the index procedure. The average cost of each visit to the healthcare system at large was $117.31 ± 60.53 (range, $93.90 - $428.28).

Conclusions. The findings of this study advise total joint patients andorthopaedic surgeons regarding the cost of routine post-operativeappointments and whether these visits alter patient management.The majority of the routine follow-up visits after THA and TKA didnot result in an alteration in patient management, but added substantialcost to the health care system. Kans J Med 2018;11(3):59-66.
La ¿relativa? aplicación del principio de legalidad en Derecho Penal Internacional
Authors: Barbero Natalia
Published: June 2019

Se asume en este texto que el Derecho penal debe adecuarse a los límites que derivan del principio de legalidad. Es por ello que se impone la revisión de la previsión del Estatuto de Roma en el cual están previstas un abanico de fuentes que resultan notoriamente extrañas al Derecho Penal. Así, no obstante los internacionalistas vean al art. 21 del Estatuto de Roma como una limitación a la amplitud de fuentes del Derecho Internacional, desde lo penal (y el Estatuto de Roma es de carácter penal) se lo ve como una exagerada y riesgosa permisión de filtración de fuentes ajenas al estricto ámbito punitivo.