bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrotransport in the La2NiO4-based solid solutions
Authors: Cherepanov Vladimir A. , Gilev Artem R. , Kiselev Evgeny A.
Published: April 2019

This work combines new and earlier obtained results on electron hole and oxygen-ion transport in the La2NiO4-based solid solutions. The effect of lanthanum substitution with Ca/Sr and nickel with Fe, Mn, Co or Cu on transport properties of La2−

x
A
x
Ni1−

y
Me
y
O4+δ was analyzed and discussed at different substitution levels. Besides the changes in concentration and mobility of electron holes induced by the doping with cations of different nature, the partial transformation of Ni3+ from low-spin to high-spin state was shown to have a profound effect on transport properties of these materials leading to a notable decrease in mobility of electron holes, especially in the strontium-rich oxides. The obtained results suggested that the size factor was the main driving force behind the observed transformation of Ni3+. The oxygen-ion transport in La2−

x
A
x
Ni1−

y
Me
y
O4+δ was characterized by significant surface exchange limitations, which can be reduced only at relatively high concentrations of strontium and iron, and should be taken into account while evaluating the ionic conductivity by means of oxygen permeation or the modified Hebb-Wagner polarization method.
Von der Gesundheitsökonomie zur Gesundheitswirtschaft
Authors: Henke Klaus-Dirk
Published: April 2019

Die Gesundheitsökonomie hat sich als Studienfach und Forschungsgebiet über die vergangenen rund 40 Jahre entwickelt. In diesem Überblicksartikel arbeitet Klaus-Dirk Henke die Ursachen heraus, verdeutlicht Besonderheiten und zieht einen Vergleich zu anderen Studienfächern. Nach diesem fachspezifischen Abschnitt folgt ein Überblick zur qualitativen und quantitativen Erfassung der Gesundheitswirtschaft sowie zu ihrem wirtschaftlichen und gesellschaftlichen Nutzen als eigenständige Wachstumsbranche mit ihren Stärken und Schwächen. Zudem enthält der Beitrag einen Exkurs zur Über- und Fehlversorgung in deutschen Krankenhäusern. Dieser Zusammenhang von Ökonomie und Medizin steht thematisch zwischen der Gesundheitsökonomie als Studienfach auf der einen Seite und der Gesundheitswirtschaft als Wirtschafts- und Industriezweig auf der anderen.
A Rule of Reason Approach for Passive Minority Interests within the European Union
Authors: Zevgolis Nikolaos E. , Fotis Panagiotis N.
Published: April 2019

In this interdisciplinary paper we analyze the anticompetitive effects and the practicability and applicability of passive (non-controlling) minority interests within the existing Merger Regulation system [Council Regulation (EC) No 139/2004 of 20 January 2004 on the control of concentrations between undertakings (the EC Merger Regulation), OJ L 24/1]. The empirical evidences from existing economic literature and case law show that the existence of an enforcement gap in European Union competition law regarding the anticompetitive effects of non-controlling minority interests has not been confirmed so far. Therefore, there is no space,at least to date, for a per se ruling in the European Union Law for the assessment of passive minority interests, but for a Rule of Reason approach, based on a case by case analysis. The Commission should continue to investigate non-controlling transactions and, in the future, an ex post assessment/quantification of their anticompetitive effects, based on existing (or settled) case law and economic theory, should be at the core of its agenda.
3rd person clitic combinations across Catalan varieties: Consequences of the nature of the dative clitic
Authors: Cabré Teresa , Fábregas Antonio
Published: April 2019

This article argues that variation in how 3rd person clitic combinations are solved across Catalan varieties depends on the internal morphosyntactic shape of the dative clitic in each variety. We argue that the dative clitic in Valencian Catalan is an inherently case-marked pronominal form (KP), while non Valencian Catalan varieties, that contain a locative clitic, build the dative as a definite locative pronominal which receives structural case. This allows Valencian Catalan to license each clitic in a different area, while non Valencian Catalan is forced to license a sequence of clitics in the same area, with the result that the two forms compete with each other for the licensing by the same head, leading to surface impoverishment of the sequence. Our analysis provides an explanation of these impoverishments as simple syntactic competition for licensing by the same set of heads, making OCP effects in morphology or syntax unnecessary as analytical devices for such cases.
Industrialisierung, Modernisierung, gesellschaftliche Entwicklung
Authors: Brandt Gerhard
Published: April 2019

Die gegenwärtige Situation auf dem Gebiet gesamtgesellschaftlicher Analysen ist geprägt durch rivalisierende Strömungen der Theoriebildung: modernisierungstheoretische Ansätze auf der einen, neo-marxistische Theorien der gesellschaftlichen Entwicklung auf der anderen Seite. Beide Strömungen erfassen wichtige Aspekte der Industrialisierungsproblematik, verfahren dabei aber selektiv und lassen nicht minder wichtige Aspekte außer acht. Ein gemeinsamer Mangel ist darin zu sehen, daß beide Ansätze sich als allgemeine Theorien der gesellschaftlichen Entwicklung verstehen und infolgedessen die historisch bedingten spezifischen Differenzen empirischer Entwicklungsprozesse vernachlässigen. Vorgeschlagen wird die Formulierung einer historischen Theorie der gesellschaftlichen Entwicklung, die sich auf die kategoriale Unterscheidung von symbolisch vermittelter Interaktion und instrumentalem Handeln stützt. Eine solche Theorie würde es erlauben, empirische Entwicklungsprozesse auf die in ihnen angelegte doppelte Zielsetzung hin zu analysieren: die Lösung der ökonomischen Wachstumsproblematik auf der einen Seite und die Auflösung von institutionalisierten Zwängen auf der andern.
Effects of Phosphorus on Loosely Bound and Tightly Bound Extracellular Polymer Substances in Aerobic Granular Sludge
Authors: Yan L. L. , Zhang X. L. , Chen Z. L. , Ren Y. , Liu S. , Zhang M. Y. , Liu Y. , Liu Q. P. , Yu L. B.
Published: April 2019

The stability of aerobic granular sludge (AGS) is closely related to its extracellular

polymeric substances (EPS). In this study, the composition and physicochemical characteristics of EPS in AGS were determined to evaluate their roles in AGS stability. The study evaluated the influence of influent phosphorus concentration on EPS protein (PN), polysaccharide (PS) and orthophosphate content, zeta potential (ζ) and fluorescence spectrum (EEM) in loosely bound EPS (LB-EPS) and tightly bound EPS (TB-EPS). With higher influent phosphorus concentration, the PN, PS and orthophosphate content were higher, as was the zeta potential in TB-EPS, but it had less influence on LB-EPS. Three-dimensional, synchronous fluorescence spectroscopy and fluorescence region integral (FRI) showed that protein-like substances were the primary components of LB-EPS and TB-EPS. Phosphorus had a dynamic quenching effect on EPS at a concentration between 0 mg L–1 and 17.5 mg L–1, which is the indirect production of phosphorus by cations. An increased concentration of influent phosphorus was beneficial to AGS stability
Physicochemical Properties, Cytotoxicity, and Antioxidative Activity of Natural Deep Eutectic Solvents Containing Organic Acid
Authors: Mitar Anamarija , Panić Manuela , Radošević Kristina , Radojčić Redovniković Ivana , Zagajski Kučan Kristina , Sander Aleksandra , Halambek Jasna , Prlić Kardum Jasna
Published: April 2019

Natural deep eutectic solvents (NADES) may be considered ‘designer solvents’ due to their numerous structural variations and the possibility of tailoring their physicochemical properties. Prior to their industrial application, characterization of NADES is essential, including determination of their physicochemical properties, cytotoxicity, and antioxidative activity. The most important physicochemical properties of eight prepared NADES (choline chloride:malic acid, proline:malic acid, choline chloride:proline:malic acid, betaine:malic acid, malic acid:glucose, malic acid:glucose:glycerol, choline chloride:citric acid, and betaine:citric acid) were measured as functions of temperature and water content. In general, the structure of prepared NADES greatly influences their physical properties, which could be successfully modified and adjusted by addition of water. All tested NADES were absolutely benign and noncorrosive for investigated steel X6CrNiTi18-10. Furthermore, cytotoxicity of prepared solvents was assessed toward three human cell lines (HEK-293T, HeLa, and MCF-7 cells), and antioxidative activity was measured by the Oxygen Radical Absorbance Capacity (ORAC) method. With regard to cell viability, all tested NADES containing carboxylic acid could be classified as practically harmless and considered environmentally safe. The ORAC values indicated that the tested NADES displayed antioxidative activity.
A Comparative Study of Bioprocess Performance for Improvement of Bioethanol Production from Macroalgae
Authors: İnan Benan , Özçimen Didem
Published: April 2019

In the last decade, studies that have focused on biodiesel production from algal biomass have been replaced with bioethanol production from algae, because bioethanol production from algae seems more promising when assessed on economic terms. Most coastal areas are covered with macroalgae, which are considered as a waste, and thus become a great problem for the municipality. Instead of their disposal, they can be alternatively utilized for bioethanol production. In this study, macroalgae located in the coastal regions of the Marmara Sea were collected and utilized for bioethanol production, and effects of the concentration of pre-treatment chemicals, pre-treatment temperature, and pre-treatment time on bioethanol yield were investigated. The highest bioethanol yields for dilute acid and alkaline pre-treatments were obtained under the conditions of 2 N sulfuric acid and 0.15 N potassium hydroxide solutions at the pre-treatment temperature of 100 °C and pre-treatment time of 60 minutes.
Adipose tissue browning in mice and humans
Authors: Herz Carsten T , Kiefer Florian W
Published: April 2019

In the midst of an obesity epidemic, the promotion of brown adipose tissue (BAT) function and the browning of white adipose tissue (WAT) have emerged as promising therapeutic targets to increase energy expenditure and counteract weight gain. Despite the fact that the thermogenic potential of bone fide BAT in rodents is several orders of magnitudes higher than white fat containing brite/beige adipocytes, WAT browning represents a particularly intriguing concept in humans given the extreme amount of excess WAT in obese individuals. In addition, the clear distinction between classic brown and beige fat that has been proposed in mice does not exist in humans. In fact, studies of human BAT biopsies found controversial results suggesting both classic brown and beige characteristics. Irrespective of the true ‘color’, accumulating evidence suggests the induction of thermogenic adipocytes in human WAT depots in response to specific stimuli, highlighting that WAT browning may occur in both, mice and humans. These observations also emphasize the great plasticity of human fat depots and raise important questions about the metabolic properties of thermogenically active adipose tissue in humans and the potential therapeutic implications. We will first review the cellular and molecular aspects of selected adipose tissue browning concepts that have been identified in mouse models with emphasis on neuronal factors, the microbiome, immune cells and several hormones. We will also summarize the evidence for adipose tissue browning in humans including some experimental pharmacologic approaches.
ERK-containing microparticles from a diabetic mouse induce endothelial dysfunction
Authors: Taguchi Kumiko , Narimatsu Haruka , Matsumoto Takayuki , Kobayashi Tsuneo
Published: April 2019

Endothelial dysfunction is a hallmark of diabetic vascular complications. Microparticles (MPs) are small vesicles shed from the surface of blood and vascular cells that act as stimuli and during apoptosis. Circulating MPs of diabetic rats have been shown to induce endothelial dysfunction. However, the underlying mechanisms require further study. In this study, we investigated how MPs from diabetic mice affect endothelial function. MPs were collected from streptozotocin-induced diabetic mice and Institute of Cancer Research (ICR) mice as controls. The levels of MPs were assessed and characterized by flow cytometry, enzyme-linked immunosorbent assay and dot blotting. Normal mice aortas were incubated with MPs and expressions of enzymes and vascular relaxation were analyzed. We found that (1) circulating MPs level increased in diabetic mice; (2) MPs impaired endothelial-dependent relaxation in mice aorta, but diabetic mice-derived MPs (diabetes mellitus (DM) MPs) were easier to attach to the endothelial cells than were control MPs; (3) DM MPs had more extracellular signal-regulated kinase (ERK)1/2 than did control mice-derived MPs, and they induced ERK1/2 activation in mice aortas; (4) DM MPs decreased endothelial nitric oxide synthase (eNOS) in mice aortas, and eNOS was emitted from endothelial cells to blood in the shape of endothelial MPs. DM MPs significantly altered endothelial function by activation of ERK1/2, which might provide a therapeutic target for diabetic vascular complications.
miR-487b-3p impairs osteoblastogenesis by targeting Notch-regulated ankyrin-repeat protein (Nrarp)
Authors: John Aijaz A , Prakash Ravi , Singh Divya
Published: April 2019

miRNAs have appeared as critical controllers of gene expression at post-transcriptional level either by degrading RNA transcripts or repressing translation. It is evident from the ever-growing scientific literature that miRNAs play a significant role in osteoblast commitment and differentiation. Here, we report that overexpression of miR-487b-3p leads to inhibition of osteoblastic differentiation. Usingin silicoapproaches, Nrarp was found to be the direct target of miR-487b-3p, which was further validated by luciferase 3′ UTR reporter assay. Nrarp inhibits Notch-1 signaling and promotes Wnt signaling by stabilization of LEF-1. Role of miR-487b-3p in regulating canonical Wnt and Notch signaling was determined by western blotting. Protein levels of Nrarp, RUNX-2, Lef1 and β catenin were reduced in osteoblasts cells transfected with miR-487b-3p, whereas protein levels of Notch1, Hes1 and P-β catenin were upregulated when osteoblast cells were transfected with miR-487b-3p. These outcomes were reversed after treating cells with anti-miR-487b-3p. Further silencing of miR-487b-3p in neonatal Balb/c mice attenuated all the inhibitory actions of miR-487b-3p on osteoblast differentiation. Importantly,in vivoaction of anti-miR-487b-3p to ovariectomized osteopenic BALB/c mice steered to significant enhancement in trabecular bone microarchitecture. Furthermore, the bio-mechanical properties of isolated femurs were enhanced in anti-miR-487b-3p-treated mice. Overall, miR-487b-3p negatively regulates osteogenesis by suppressing Nrarp expression, which in turn, suppresses Runx-2 and Wnt signaling, both of which play a pivotal action in osteoblast differentiation.
Representaciones de la Amazonia en cuatro libros de literatura testimonial del secuestro en Colombia
Authors: Romero Leal Karen Lorena
Published: April 2019

A partir del análisis de cuatro libros testimoniales del secuestro de personas del grupo de “los canjeables” se evidencia que la Amazonia es representada a través de dos de las imágenes recurrentes que sobre esta región se han emitido en la historia de su contacto con Occidente: un paraíso abudante en recursos naturales y un infierno verde. La primera de las imágenes responde al imaginario conservacionista de la naturaleza conceptualizada como medio ambiente, en el marco del discurso de la posibilidad de una crisis climática inminente. La segunda, que es la percepción de la Amazonia como un infierno que consume a quien cae en sus redes, se circunscribe a los espacios construidos por la guerrilla y que fueron experimentados con ellos. La representación de la Amazonia está en conexión con el drama que viven las víctimas del secuestro, cuya experiencia individual también se vive de manera grupal, así como transita desde las relaciones entre los seres humanos y de éstos con la naturaleza. Por tanto, la sensación apabulladora del dosel oscuro de la selva y de sus minúsculos, pero incómodos animales, se resalta como escenario del sufrimiento emocional y físico de los cautivos. Así, los libros analizados despliegan un discurso conformado por imaginarios sobre la Amazonia que se pliegan al proyecto social específico delos sectores más influyentes en los campos de la política y la economía en el país. Una de sus narrativas establece que tales territorios están totalmente disponibles para la inversión de capital luego de que sean liberados del dominio de los grupos rebeldes.
Toward Spider Glue: Long Read Scaffolding for Extreme Length and Repetitious Silk Family Genes AgSp1 and AgSp2 with Insights into Functional Adaptation
Authors: Stellwagen Sarah D , Renberg Rebecca L
Published: April 2019

An individual orb weaving spider can spin up to seven different types of silk, each with unique functions and material properties. The capture spiral silk of classic two-dimensional aerial orb webs is coated with an amorphous glue that functions to retain prey that get caught in a web. This unique modified silk is partially comprised of spidroins (spider fibroins) encoded by two members of the silk gene family. The glue differs from solid silk fibers as it is a viscoelastic, amorphic, wet material that is responsive to environmental conditions. Most spidroins are encoded by extremely large, highly repetitive genes that cannot be sequenced using short read technology alone, as the repetitive regions are longer than read length. We sequenced for the first time the complete genomic Aggregate Spidroin 1 (AgSp1) and Aggregate Spidroin 2 (AgSp2) glue genes of orb weaving spider Argiope trifasciata using error-prone long reads to scaffold for high accuracy short reads. The massive coding sequences are 42,270 bp (AgSp1) and 20,526 bp (AgSp2) in length, the largest silk genes currently described. The majority of the predicted amino acid sequence of AgSp1 consists of two similar but distinct motifs that are repeated ∼40 times each, while AgSp2 contains ∼48 repetitions of an AgSp1-similar motif, interspersed by regions high in glutamine. Comparisons of AgSp repetitive motifs from orb web and cobweb spiders show regions of strict conservation followed by striking diversification. Glues from these two spider families have evolved contrasting material properties in adhesion (stickiness), extensibility (stretchiness), and elasticity (the ability of the material to resume its native shape), which we link to mechanisms established for related silk genes in the same family. Full-length aggregate spidroin sequences from diverse species with differing material characteristics will provide insights for designing tunable bio-inspired adhesives for a variety of unique purposes.
An Interaction Network of the Human SEPT9 Established by Quantitative Mass Spectrometry
Authors: Hecht Matthias , Rösler Reinhild , Wiese Sebastian , Johnsson Nils , Gronemeyer Thomas
Published: April 2019

Septins regulate the organization of the actin cytoskeleton, vesicle transport and fusion, chromosome alignment and segregation, and cytokinesis in mammalian cells. SEPT9 is part of the core septin hetero-octamer in human cells which is composed of SEPT2, SEPT6, SEPT7, and SEPT9. SEPT9 has been linked to a variety of intracellular functions as well as to diseases and diverse types of cancer. A targeted high-throughput approach to systematically identify the interaction partners of SEPT9 has not yet been performed. We applied a quantitative proteomics approach to establish an interactome of SEPT9 in human fibroblast cells. Among the newly identified interaction partners were members of the myosin family and LIM domain containing proteins. Fluorescence microscopy of SEPT9 and its interaction partners provides additional evidence that SEPT9 might participate in vesicle transport from and to the plasma membrane as well as in the attachment of actin stress fibers to cellular adhesions.
Genetic Variation for Ontogenetic Shifts in Metabolism Underlies Physiological Homeostasis in Drosophila
Authors: Matoo Omera B , Julick Cole R , Montooth Kristi L
Published: April 2019

Organismal physiology emerges from metabolic pathways and structures that can vary across development and among individuals. Matoo, Julick, and Montooth found significant variation, both genetic and ontogenetic, in mitochondrial physiology in wild-type and mitochondrial-nuclear...

Organismal physiology emerges from metabolic pathways and subcellular structures like the mitochondria that can vary across development and among individuals. Here, we tested whether genetic variation at one level of physiology can be buffered at higher levels of biological organization during development by the inherent capacity for homeostasis in physiological systems. We found that the fundamental scaling relationship between mass and metabolic rate, as well as the oxidative capacity per mitochondria, changed significantly across development in the fruit fly Drosophila. However, mitochondrial respiration rate was maintained at similar levels across development. Furthermore, larvae clustered into two types—those that switched to aerobic, mitochondrial ATP production before the second instar, and those that relied on anaerobic, glycolytic production of ATP through the second instar. Despite genetic variation for the timing of this metabolic shift, metabolic rate in second-instar larvae was more robust to genetic variation than was the metabolic rate of other instars. We found that larvae with a mitochondrial-nuclear incompatibility that disrupts mitochondrial function had increased aerobic capacity and relied more on anaerobic ATP production throughout development relative to larvae from wild-type strains. By taking advantage of both ways of making ATP, larvae with this mitochondrial–nuclear incompatibility maintained mitochondrial respiratory capacity, but also had higher levels of whole-body reactive oxygen species and decreased mitochondrial membrane potential, potentially as a physiological defense mechanism. Thus, genetic defects in core physiology can be buffered at the organismal level via physiological plasticity, and natural populations may harbor genetic variation for distinct metabolic strategies in development that generate similar organismal outcomes.
Foreign-Body Ingestions of Young Children Treated in US Emergency Departments: 1995–2015
Authors: Orsagh-Yentis Danielle , McAdams Rebecca J. , Roberts Kristin J. , McKenzie Lara B.
Published: April 2019

OBJECTIVES:

To describe the epidemiology of foreign-body ingestions (FBIs) of children <6 years of age who were treated in US emergency departments from 1995 to 2015.

METHODS:

We performed a retrospective analysis using data from the National Electronic Injury Surveillance System for children <6 years of age who were treated because of concern of FBI from 1995 to 2015. National estimates were generated from the 29 893 actual cases reviewed.

RESULTS:

On the basis of those cases, 759 074 children <6 years of age were estimated to have been evaluated for FBIs in emergency departments over the study period. The annual rate of FBI per 10 000 children increased by 91.5% from 9.5 in 1995 to 18 in 2015 (R2 = 0.90; P < .001). Overall, boys more frequently ingested foreign bodies (52.9%), as did children 1 year of age (21.3%). Most children were able to be discharged after their suspected ingestion (89.7%). Among the types of objects ingested, coins were the most frequent (61.7%). Toys (10.3%), jewelry (7.0%), and batteries (6.8%) followed thereafter. The rates of ingestions of those products also increased significantly over the 21-year period. Across all age groups, the most frequently ingested coin was a penny (65.9%). Button batteries were the most common batteries ingested (85.9%).

CONCLUSIONS:

FBIs remain common in children <6 years of age, and their rate of ingestions has increased over time. The frequency of ingestions noted in this study underscores the need for more research to determine how best to prevent these injuries.
Packaging perspective of milk and dairy products
Authors: Ščetar Mario , Barukčić Irena , Kurek Mia , Lisak Jakopović Katarina , Božanić Rajka , Galić Kata
Published: April 2019

Packaging of dairy products develops continuously along with advances in
material technologies, which are in turn a response to demands of consumers. This article aimed to give an overview of currently available
dairy packaging systems. Novel dairy packaging systems include new packaging technologies such as the modified atmosphere packaging (MAP) that is widely used nowadays, especially for dairy product like cheese. Application of edible packaging could significantly reduce the costs of cheese packaging by reducing the amount of usually required packaging material. Nanomaterials and active packaging might be useful for extending the shelf life of dairy products by reducing material permeability or negative sensory characteristics of batch processing. Forms of active packaging relevant to dairy foods include oxygen scavenging, carbon dioxide absorbers, moisture and/or flavour/odour taints absorbers; releasing compounds (carbon dioxide, ethanol, antioxidants and/or other preservatives); maintaining temperature control and/or compensating temperature changes and antimicrobial packaging. Antimicrobial packaging is gaining interest from packaging scientists and industry due to its potential for providing quality and their safety benefits. The greatest challenge from the ecological point of view is biodegradable packaging. The main challenges for low waste materials are the durability of the packaging correlated with product shelf life as well as the ecological perspective.
Effect of composition and proteolysis on textural characteristics of Croatian cheese ripen in a lamb skin sack (Sir iz mišine)
Authors: Rako Ante , Tudor Kalit Milna , Petrović Denis , Kalit Samir , Rako Zorica
Published: April 2019

The objective of this study was to determine the effect of composition and proteolysis on textural characteristics of Croatian cheese in a lamb
skin sack (Sir iz mišine) over a ripening period of 30 days. Ten ovine milk cheese batches were manufactured according to the traditional manufacturing procedures. The content of total solids, fat, proteins (P<0.05) and salt (P<0.01) significantly increased during cheese ripening. Results of this research showed that αs1-casein hydrolysed more rapid in comparison to the β-casein. An extensive and significant (P<0.05) degradation of αs1-casein was accompanied by significant (P<0.05) accumulation of αs1-I-casein. Although β-casein degradation occurred in cheese to a moderate degree, these changes were not statistically significant. However, the level of γ-casein increased significantly (P<0.01) in cheese throughout ripening. Due to the extensive proteolysis, both TCA-SN (P<0.01) and WSN (P<0.05) significantly increased throughout ripening time. Results showed significant decrease (P<0.05) in hardness, cohesiveness and springiness during cheese ripening along with progress of proteolysis. Weakening effect of caseinolysis predominated over the strengthening effect of moisture loss in the texture development of cheese, which could be attributed to the specific conditions in the animal skin sack during ripening.
Persistence of heat stress eff ect in dairy cows
Authors: Gantner Vesna , Bobić Tina , Potočnik Klemen , Gregić Maja , Kučević Denis
Published: April 2019

In order to determine the persistence of heat stress effect in dairy cows regarding the breed, parity and susceptibility to heat stress, over
1.9 million of test-day records from Holstein and Simmental cows reared
in Croatia were used. The persistence of heat stress effect in the subsequent milk recordings was determined in cows that had significant decrease of daily milk yield at different THI threshold value (65, 70, 75, 80, and 85). The obtained results indicate that cows heat stressed at lower THI threshold value had higher proportional drop of daily milk yield in subsequent milk recordings. Also, primiparous and Simmentals experienced higher proportional drop when compared to multiparous and Holsteins. The negative effect of heat stress on daily milk contents that existed in all cows was more pronounced in the 2nd subsequent milk recording. The determined increase of somatic cell count in more heat stress sensitive Holsteins (THI in 65, 70, 75) indicates that Holstein cows, in terms of heat stress, also become more susceptible to mastitis.
Finally, the lower was the THI threshold value, the stronger and more persistent was the heat stress effect. Considering the quite probable increase of the frequency of heat stress days, it is necessary to develop an adequate strategy for dairy farming. Aiming the accurate answer to the problem of heat stress in this region, it is necessary to conduct further research on genetic evaluation.
Influence of purple basil extract (Ocimum basilicum L.) on chemical composition, rheology and antioxidant activity of set-type yoghurt
Authors: Gurkan Hacer , Seracettin Boran Osman , Adnan Hayaloglu Ali
Published: April 2019

Four different types of yoghurt were manufactured using purple basil which was added to milk as water extract or powder forms at levels of 1.0 % and 0.4 % (w/w). Physicochemical and rheological properties, antioxidant capacity, color and total phenolic contents of yoghurt samples were measured during 21 days of storage. None of changes were observed for titratable acidity, pH and hardness parameters of yoghurt samples; however, some changes were observed during storage. The contents for total phenolic compounds and antioxidant activity [2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid diammonium salt (ABTS+*) and 2,2-Diphenyl-1-picrylhydrazyl (DPPH*) values] were dramatically higher in powder-added yoghurt samples than those of its water extract counterparts, while the lowest total phenolics and ABTS+* were observed in control sample during storage. The values for storage and loss modulus were higher in water extract-added samples than powder-added counterparts. In conclusion, no significant effect of the addition of powder or water extract of basil was observed on gross chemical characteristics of yoghurt, while use of basil powder positively contributed to antioxidant activity and changed the rheological behavior of yoghurt gel.
High reflectance III-Nitride Bragg reflectors grown by molecular beam epitaxy
Authors: Ng H. M. , Moustakas T. D.
Published: April 2019

Distributed Bragg reflector (DBR) structures based on AlN/GaN have been grown on (0001) sapphire by electron-cyclotron-resonance plasma-assisted molecular-beam epitaxy (ECR-MBE). The design of the structures was predetermined by simulations using the transmission matrix method. A number of structures have been grown with 20.5 – 25.5 periods showing peak reflectance ranging from the near-UV to the green wavelength regions. For the best sample, peak reflectance up to 99% was observed centered at 467 nm with a bandwidth of 45 nm. The experimental reflectance data were compared with the simulations and show excellent agreement with respect to peak reflectance, bandwidth of high reflectance and the locations of the sidelobes.
A Study of the Effect of V/III Flux Ratio and Substrate Temperature on the in Incorporation Efficiency in InxGa1−x/GaN Heterostructures Grown by RF Plasma-Assisted Molecular Beam Epitaxy
Authors: O’Steen M. L. , Fedler F. , Hauenstein R. J.
Published: April 2019

Laterally resolved high resolution X-ray diffraction (HRXRD) and photoluminescence spectroscopy (PL) have been used to assess In incorporation efficiency in InxGa1−xN/GaN heterostructures grown through rf-plasma-assisted molecular beam epitaxy. Average alloy composition over a set of InxGa1−xN/GaN superlattices has been found to depend systematically upon both substrate temperature (Tsub) and V/III flux ratio during growth. A pronounced thermally activated In loss (with more than an order-of-magnitude decrease in average alloy composition) is observed over a narrow temperature range (590–670°C), with V/III flux ratio fixed. Additionally, the V/III flux ratio is observed to further strongly affect In incorporation efficiency for samples grown at high Tsub, with up to an order-of-magnitude enhancement in In content despite only a minor increase in V/III flux ratio. PL spectra reveal redshifts as In content is increased and luminescence efficiency which degrades rapidly with decreasing Tsub. Results are consistent with In loss arising from thermally activated surface segregation + surface desorption processes during growth.
Structural evolution of GaN during initial stage MOCVD growth
Authors: Kim Chong Cook , Je Jung Ho , Yi Min-Su , Noh Do Young
Published: April 2019

The structural evolution of GaN films during the initial growth process of metalorganic chemical vapor deposition (MOCVD) - low temperature nucleation layer growth, annealing, and high temperature epitaxial growth - was investigated in a synchrotron x-ray scattering experiment. The nucleation layer grown at 560°C that was predominantly cubic GaN consisted of tensile-strained aligned domains and relaxed misaligned domains. The hexagonal GaN, transformed from the cubic GaN during annealing to 1100 °C, showed disordered stacking. The atomic layer spacing decreased as the fraction of the hexagonal domains increased. Subsequent growth of epitaxial GaN at 1100 °C resulted in the formation of ordered hexagonal GaN domains with rather broad mosaicity.
Surface activity of magnesium during GaN molecular beam epitaxial growth
Authors: Ramachandran V. , Feenstra R. M. , Northrup J. E. , Greve D. W.
Published: April 2019

Exposure of wurtzite GaN films grown on Si-polar 6H-SiC(0001) to magnesium during molecular beam epitaxy (MBE) has been studied. In the nitrogen rich regime of MBE growth, GaN films are known to grow with rough morphology. We observe on GaN(0001) that small doses of Mg act as a surfactant, smoothing out this roughness. An interpretation of this surfactant behavior is given in terms of electron counting arguments for the surface reconstructions. Previously, we have reported that larger doses of Mg lead to inversion of the Ga-polar GaN film to produce N-polar GaN. Several Mg-related reconstructions of the resulting GaN(000 ) surface are reported.
Simulations of Defect-Interface Interactions in GaN
Authors: Chisholm J. A. , Bristowe P. D.
Published: April 2019

We report on the interaction of native point defects with commonly observed planar defects in GaN. Using a pair potential model we find a positive binding energy for all native defects to the three boundary structures investigated indicating a preference for native defects to form in these interfaces. The binding energy is highest for the Ga interstitial and lowest for vacancies. Interstitials, which are not thought to occur in significant concentrations in bulk GaN, should form in the (11 0) IDB and the (10 0) SMB and consequently alter the electronic structure of these boundaries.
Optical and Electrical Properties of MBE Grown Cubic GaN/GaAs Epilayers Doped by Si
Authors: As D.J. , Richter A. , Busch J. , Schöttker B. , Lübbers M. , Mimkes J. , Schikora D. , Lischka K. , Kriegseis W. , Burkhardt W. , Meyer B.K.
Published: April 2019

Si-doping of cubic GaN epilayers grown by an rf plasma-assisted molecular beam epitaxy on semi-insulating GaAs (001) substrates is investigated by secondary ion mass spectroscopy (SIMS), photoluminescence (PL) and by Hall-effect measurements. SIMS measurements show a homogeneous incorporation of Si in cubic GaN epilayers up to concentrations of 5*1019 cm−3. PL shows a clear shift of the donor-acceptor emission to higher energies with increasing Si-doping. Above a Si-flux of 1*1011cm−2s−1 the near band edge lines merge to one broad band due to band gap renormalization and conduction band filling effects. The influence of the high dislocation density (≈1011cm−2) in c-GaN:Si on the electrical properties is reflected in the dependence of the electron mobility on the free carrier concentration. We find that dislocations in cubic GaN act as acceptors and are electrically active.
Doping Dependence Of The Thermal Conductivity Of Hydride Vapor Phase Epitaxy Grownn-GaN/Sapphire (0001) Using A Scanning Thermal Microscope
Authors: Florescu D.I. , Asnin V.A. , Mourokh L.G. , Pollak Fred H. , Molnar R. J.
Published: April 2019

We have measured the doping concentration dependence of the room temperature thermal conductivity (κ) of two series ofn-GaN/sapphire (0001) fabricated by hydride vapor phase epitaxy (HVPE). In both setsκdecreased linearly with logn, the variation being about a factor two decrease inκfor every decade increase inn.κ≈ 1.95 W/cm-K was obtained for one of the most lightly doped samples (n= 6.9×1016cm−3), higher than the previously reportedκ≈ 1.7-1.8 W/cm-K on lateral epitaxial overgrown material [V.A. Asninet al, Appl. Phys. Lett.75, 1240 (1999)] andκ≈ 1.3 W/cm-K on a thick HVPE sample [E.K. Sichel and J.I. Pankove, J. Phys. Chem. Solids38, 330 (1977)]. The decrease in the lattice component ofκdue to increased phonon scattering from both the impurities and free electrons outweighs the increase in the electronic contribution toκ.
TEM Study of Bulk AlN Growth by Physical Vapor Transport
Authors: Sarney W.L. , Salamanca-Riba L. , Hossain T. , Zhou P. , Jayatirtha H.N. , Kang H.H. , Vispute R.D. , Spencer M. , Jones K.A.
Published: April 2019

We are attempting to grow bulk AlN that would be suitable as a substrate for nitride film growth. Bulk AlN films were grown by physical vapor transport on 3.5° off-axis and on-axis 6H SiC seed crystals and characterized by TEM, x-ray-diffraction, Auger electron microscopy, and SEM. TEM images show that the bulk AlN does not have the columnar structure typically seen in AlN films grown by MOCVD. Although further optimization is required before the bulk AlN is suitable as a substrate, we find that the structural characteristics achieved thus far indicate that quality bulk AlN substrates may be obtained in the future.
The Role of the Multi Buffer Layer Technique on the Structural Quality of GaN
Authors: Benamara M. , Liliental-Weber Z. , Mazur J.H. , Swider W. , Washburn J. , Iwaya M. , Akasaki I. , Amano H.
Published: April 2019

Successive growth of thick GaN layers separated by either LT-GaN or LT-AlN interlayers have been investigated by transmission electron microscopy techniques. One of the objectives of this growth method was to improve the quality of GaN layers by reducing the dislocation density at the intermediate buffer layers that act as barriers to dislocation propagation. While the use of LT-AlN results in the multiplication of dislocations in the subsequent GaN layers, the LT-GaN reduces dislocation density. Based upon Burgers vector analysis, the efficiency of the buffer layers for the propagation of the different type of dislocations is presented. LT-AlN layer favor the generation of edge dislocations, leading to a highly defective GaN layer. On the other hand, the use of LT-GaN as intermediate buffer layers appears as a promising method to obtain high quality GaN layer.
Structural and Electronic Properties of Line Defects in GaN
Authors: Elsner Joachim , Blumenau Alexander Th. , Frauenheim Thomas , Jones Robert , Heggie Malcolm I.
Published: April 2019

We present density-functional theory based studies for several types of line defects in both hexagonal and cubic GaN. {10−10} type surfaces play an important role in hexagonal GaN since similar configurations occur at open-core screw dislocations and nanopipes as well as at the core of threading edge dislocations. Except for full-core screw dislocations which possess heavily strained bonds all investigated stoichiometric extended defects in hexagonal GaN do not induce deep acceptor states in the band-gap and thus cannot be responsible for the yellow luminescence. However, electrically active point defects in particular gallium vacancies and oxygen related defect complexes are found to be trapped at the stress field of the dislocations. Preliminary calculations for cubic GaN find the ideal stoichiometric 60°-dislocations to be electrically active. As in hexagonal material, vacancies and impurities like oxygen are likely to be trapped at the dislocation core.
Properties and Effects of Hydrogen in GaN
Authors: Pearton S.J. , Cho H. , Ren F. , Chyi J.-I. , Han J. , Wilson R.G.
Published: April 2019

The status of understanding of the behavior of hydrogen in GaN and related materials is reviewed. In particular, we discuss the amount of residual hydrogen in MOCVD-grown device structures such as heterojunction bipolar transistors, thyristors and p-i-n diodes intended for high power, high temperature applications. In these structures, the residual hydrogen originating from the growth precursors decorates Mg-doped layers and AlGaN/GaN interfaces. There is a significant difference in the diffusion characteristics and thermal stability of implanted hydrogen between n- and p-GaN, due to the stronger affinity of hydrogen to pair with acceptor dopants and possibly to the difference in H2 formation probability.
Surface Conversion Effects in Plasma-Damaged p-GaN
Authors: Cao X.A. , Pearton S.J. , Dang G.T. , Zhang A.P. , Ren F. , Shul R.J. , Zhang L. , Hickman R. , Van Hove J.M.
Published: April 2019

The near-surface (400-500Å) of p-GaN exposed to high density plasmas is found to become more compensated through the introduction of shallow donors. At high ion fluxes or ion energies there can be type-conversion of this surface region. Two different methods for removal of the damaged surface were investigated; wet etching in KOH, which produced self-limiting etch depths or thermal annealing under N2 which largely restored the initial electrical properties.
Vertical Transport Properties of GaN Schottky Diodes Grown by Molecular Beam Epitaxy
Authors: Misra M. , Sampath A.V. , Moustakas T.D.
Published: April 2019

Lateral and vertical electron transport parameters were investigated in lightly doped n-GaN films, grown by MBE. Diodes were fabricated by forming Schottky barriers on n−-GaN films using a mesa-etched vertical geometry. Doping concentrations and barrier heights were determined, from C-V measurements, to be 8-9×1016 cm−3 and 0.95-1.0 eV respectively. Reverse saturation current densities were measured to be in the 1-10×10−9 A/cm2 range. Using the diffusion theory of Schottky barriers, vertical mobility values were determined to be 950 cm2/V-s. Lateral mobility in films grown under similar conditions was determined by Hall effect measurements to be 150-200 cm2/V-s. The significant increase in mobility for vertical transport is attributed to reduction in electron scattering by charged dislocations.
Low-Frequency Noise in SiO2 /AlGaN/GaN Heterostructures on SiC and Sapphire Substrates
Authors: Pala N. , Gaska R. , Shur M. , W Yang J. , Asif Khan M.
Published: April 2019

The low-frequency noise in GaN-based Metal-Oxide-Semiconductor Heterostructure Field Effect Transistors (MOS-HFETs) and HFETs on sapphire and n-SiC substrates were studied. Hooge parameter at zero gate bias was calculated about 8 × 10−4 for both types of the devices. The AlGaN/GaN MOS-HFETs exhibited extremely low gate leakage current and much lower noise at both positive and negative gate biases. These features demonstrate the high quality of the SiO2/AlGaN heterointerface and feasibility of this technology for high-power microwave transmitter and high-power, high-temperature switches.
Full Band Monte Carlo Comparison of Wurtzite and Zincblende Phase GaN MESFETs
Authors: Farahmand Maziar , Brennan Kevin F.
Published: April 2019

The output characteristics, cutoff frequency, breakdown voltage and the transconductance of wurtzite and zincblende phase GaN MESFETs have been calculated using a self-consistent, full band Monte Carlo simulation. It is found that the calculated breakdown voltage for the wurtzite device is considerably higher than that calculated for a comparable GaN zincblende phase device. The zincblende device is calculated to have a higher transconductance and cutoff frequency than the wurtzite device. The higher breakdown voltage of the wurtzite phase device is attributed to the higher density of electronic states for this phase compared to the zincblende phase. The higher cutoff frequency and transconductance of the zincblende phase GaN device is attributed to more appreciable electron velocity overshoot for this phase compared to that for the wurtzite phase. The maximum cutoff frequency and transconductance of a 0.1 μm gate-length zincblende GaN MESFET are calculated to be 220GHz and 210 mS/mm, respectively. The corresponding quantities for the wurtzite GaN device are calculated to be 160GHz and 158 mS/mm.
Dependence of aging on inhomogeneities in InGaN/AlGaN/GaN light-emitting diodes
Authors: Kudryashov V.E. , Mamakin S.S. , Turkin A.N. , Yunovich A.E. , Kovalev A.N. , Manyakhin F.I.
Published: April 2019

Changes of properties of green LEDs based on InxGa1−xN/AlyGa1−y/GaN heterostructures were studied during 150÷200 hours at currents J = 30÷ 80 MA The radiation intensity at low currents (0.1÷1 mA) is quite sensitive to such an aging, it falls down 10÷100 times. Quantum efficiency and spectral parameters at normal currents (J ≈ 10 mA) change non-monotonically during aging, some degradation is observed after 168 hours. The degradation is observed also after a short (< 1 min) period of reverse current. These phenomena are discussed in terms of under threshold defect’s formation and their migration in the space charge region of p-n-heterojunction. Potential fluctuations in the space charge region are quite sensitive to this process.
Photoluminescence and Cathodoluminescence of GaN doped with Pr
Authors: Lozykowski H. J. , Jadwisienczak W. M. , Brown I.
Published: April 2019

In this paper we have reported the observation of visible photoluminescence (PL) and cathodoluminescence (CL) of Pr implanted in GaN. The implanted samples were given isochronal thermal annealing treatments at a temperature of 11000 C in NH3, N2, Ar2, and in forming gas N2 +H2, at atmospheric pressure to recover implantation damages and activate the rare earth ions. The sharp characteristic emission lines corresponding to Pr3+ intra-4fn-shell transitions are resolved in the spectral range from 350 nm to 1150 nm, and observed over the temperature range of 12 K-335 K. The PL and CL decay kinetics measurement was performed for 3P1, 3P0 and 1D2 levels.
Metal/GaN contacts studied by electron spectroscopies
Authors: Dumont J. , Caudano R. , Sporken R. , Monroy E. , Muñoz E. , Beaumont B. , Gibart P.
Published: April 2019

Au/GaN and Cu/GaN Schottky contacts have been studied using X-ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES). Clean and stoechiometric GaN samples were obtained using in situ hydrogen plasma treatment and Ga deposition. The growth of Cu and Au follows Stranski-Krastanov and Frank van der Merwe modes respectively. The interfaces are sharp and non-reactive. Schottky barriers of 1.15eV for Au/GaN and 0.85eV for Cu/GaN were measured using XPS.