bluuebunny/crossref_metadata_2025 huggingface dataset:
Characteristics of Fish Protein Hydrolysate from Yellowstripe Scad (Selaroides leptolepis) Produced by a Local Microbial Protease
Authors: Fawzya Yusro Nuri , Nursatya Safira M. , Susilowati Rini , Chasanah Ekowati
Published: February 2020

Fish protein hydrolysate (FPH) containing small protein or peptides and amino acids has a great attention related to the provision of high protein foods to overcome the problem of malnutrition. This research was purposed to prepare FPH from yellowstripe scad (Selaroides leptolepis) by using a local microbial protease from Bacillus subtilis BII-1. Hydrolysis process was done in a laboratory scale (500 g minced fish) at 55oC for 6 h. The liquid hydrolysate was then spray dried using whey protein and maltodextrin at a concentration of 20 and 30% for each filler. The treatment of whey protein powder produced FPHs with higher protein content (31.71-33.97% db) and slightly yellowish in color compared to maltodextrin (11.88-16.66% db). Their foaming capacity and stability were 20-100% and 15% in 5-10 min, respectively. However, FPHs prepared with maltodextrin had no foaming capacity. The hydrolysates from both treatments had low water and oil absorption with the value less than 3 mL/g hydrolysate. A trial on scaling up production using 30 kg fish, showed that optimization or adjustment should be carried out due to the high amount and high protein content of the residual products.
Growth Rate and Histamine Production of Citrobacter freundii CK01 in Various Incubation Temperatures
Authors: Margareta Grace , Ratnawati Susana Endah , Puspita Indun Dewi
Published: February 2020

Improper handling and temperature fluctuations during postharvest of fish commonly allow the growth of histamine-forming bacteria (HFB) that may cause histamine poisoning. Citrobacter freundii CK01 is one of the HFB isolated from Skipjack landed on Sadeng, Yogyakarta. This study aimed to determine the temperature effect on the growth rate and histamine production by C. freundii CK01. Bacterial growth and histamine production was tested in tuna fish infusion broth (TFIB) at 5, 15, 30 and 40°C. The bacterial growth was tested using Total Plate Count method, while histamine was determined using Thin Layer Chromatography and densitometry method. The primary model for bacterial growth was plotted with incubation time using DMFit referred to Baranyi & Roberts model. The secondary model was converted from growth rate and modeled using Ratkowsky Square Root Model. The equation for growth rate of C. freundii CK01 was μmax=[0.0105 (T + 13.886)]2 (Root Mean Square Error <10%). Histamine production reached the highest concentration at 15°C in 96 hours up to 117,13 ppm. This study shows that temperature affected the growth rate and histamine production of C. freundii, indicating the importance of maintaining the low temperature stability during handling of skipjack.
Physical Properties of the Probiotic Effervescent Tablet from Tapioca and Maltodextrin Coatings
Authors: Oktavia Devi Ambarwaty , Ayudiarti Diah Lestari , Febrianti Dita
Published: February 2020

The purpose of this study was to determine the physical properties of probiotic effervescent tablets with two different coatings that are tapioca and maltodextrin to improve water quality in shrimp farming ponds. This study used probiotics to improve the environmental quality of shrimp pond waters. Liquid probiotics from Research Institute for Coastal Aquaculture in Maros, South Sulawesi that containBrevibacillus laterosporus. Probiotics that have been used are liquid and difficult to transport, therefore microencapsulation is carried out on liquid probiotics aimed at facilitating their distribution. The use of microencapsulating materials is to entrap or immobilize probiotic bacteria within microcapsule and to protect the bacteria during the drying process. Effervescent tablets were prepared in a dosage of 800 mg by wet granulation methods. This experiment was replicated 3 times. Tablets were evaluated for their physical properties there are mean weight, friability, hardness, disintegration time and pH. The results showed that mean weight for effervescent tablets with maltodextrin coatings was 796 mg, had a friability value 0.09%, a hardness value of 13.7 N and disintegration time of 10.68 minutes. Both probiotic effervescent tablets meet the standards pH of 7.07 and 6.67. The maltodextrin coatings was the best treatment of this study.
Characteristics of Cookies Formulated with Fish Protein Concentrate Powder Produced from Snakehead Fish (Channa striata) Extraction By-Product
Authors: Ikasari Diah , Hastarini Ema , Suryaningrum Theresia Dwi
Published: February 2020

Snakehead fish (Channa striata) is known as a species which is consumed by local people as functional food due to its benefits in the post operation recovery process. The extraction of snakehead fish for functional food produces solid by-product that can be utilized into Fish Protein Concentrate (FPC) powder. The FPC powder can be applied into various food products, including cookies. Study aimed to investigate the characteristics of cookies formulated with FPC powder resulted from Snakehead by-product. Study showed that addition of 5 and 10% FPC powder into cookies formulation increased fat and protein contents, improves texture as well as appearance of cookies. FPC powder with concentration of 10% resulted in cookies with higher protein content (11,41%), texture and appearance. However, further study is suggested to eliminate the fishy odor and taste produced by FPC.
The Utilization of Catfish Bone Waste as Microcalcium by Different Preparation Methods
Authors: Ratnawati Susana Endah , Ekantari Nurfitri , Ustadi
Published: February 2020

In order to improve the quality of catfish bone flour, the sol-gel method was used to extract calcium. The purpose of the research was to compare calcium characterization, specifically chemical and physical quality based on discrepancy extraction methods. Completely Random Design was used as a factor with different calcium extraction, which were sol-gel method with agitation, a sol-gel treatment without agitation and the conventional way. Each treatment replicated in three folds. The results showed that the sol-gel process with agitation increased catfish bone flour quality (p<0.05), namely calcium (16.02%) and phosphor (5.13). Compared to the conventional method, the sol-gel way with and without agitation reduced particle size from from micro to sub-micro size by 174.67 µm to 3.82 and 5.12 µm respectively. The highest whiteness index (84.18) made micro calcium prepared by sol-gel method with agitation process as prospective for food fortification. Based on microscopic observation, catfish bone flour has calcite shape and stable structure which prospective used to substitute calcium loss in the bone.
Development of the unit for testing the methods of remote computerized monitoring of environmental changes in the “IKI-Monitoring” center for collective use
Authors: Loupian Evgeny , Savorskiy Viktor , Kashnitskii Aleksandr , Kobets Dmitrii , Sen'ko Konstantin , Balashov Ivan , Uvarov Ivan
Published: February 2020

The impact of hazardous waste on people and the environment from agricultural, industrial, military and mining activities form one of the most significant global environmental challenges. These wastes often include heavy metals, acid precipitates (sulfur oxide solutions), hydrocarbons, and other organic chemicals. Creation of the tools of the VEGA-Science service (http://sci-vega.ru/) to control the state of vegetation for the monitoring the impact of technogenic waste and dumps sources (TWDS) on the environment is the main objective of this work. To achieve this goal, proposals for the modernization and development of the VEGA-Science services have been defined to provide the organization and analysis of long-term variability of the vegetation cover caused by the influence of TWDS.
Conceptual model of operational–analytical data marts for big data processing
Authors: Raevich Aleksey , Dobronets Boris , Popova Olga , Raevich Ksenia
Published: February 2020

Operational data marts that basically constitute slices of thematic narrowly-focused information are designed to provide operational access to big data sources due to consolidation and ranking of information resources based on their relevance. Unlike operational data marts dependent on the sources, analytical data marts are considered as independent data sources created by users to provide structuring of data for the tasks being solved. Therefore, the conceptual model of operational-analytical data marts allows combining the concepts of operational and analytical data marts to generate an analytical cluster that shall act as the basis for quick designing, development and implementation of data models.
The objective assessment of the image quality based on the geometrical concentration
Authors: Maltsev Evgenii A. , Maglinets Yurii A. , Brezhnev Ruslan V.
Published: February 2020

The method of the objective evaluation of the satellite images based on the calculation of the geometrical concentration using triangulation Delaunay is proposed. Such assessment allows to estimate the degree of the image distortion and can be used for indexing and filtration data in the satellite images catalogues.
The productivity of agrocoenosis in the steppe zone of Khakasia according to Terra Modis
Authors: Zhukova Elena , Kutkina Natalya , Zhukov Alexander
Published: February 2020

The article presents the results of a quantitative assessment of the productivity of agrocoenosis according to Terra MODIS within the steppe zone of Khakasia. The gross primary production of various agrocoenosis during the growing season ranges from 3.42 to 7.41 kg/m2. On average, the integral productivity for the growing season of 2018 was for wheat – 5.01 ± 1.04 kg / m2, oats – 4.86 ± 1.12 kg / m2, barley – 4.52 ± 0.42 kg / m2, buckwheat – 5.25 kg / m2, hayfields – 4.86 ± 0.45 kg / m2, deposits – 4.39 ± 0.40 kg / m2. Least of all phytomass were some arable fields and low-yielding crops of wheat and abandoned lands, and most of all perennial grasses and high-yielding wheat and oats. The GPP indicators are associated with the sum of positive temperatures positively (R2×0.673), to a lesser extent (R2×0.333) with a hydrothermal coefficient for the examined agrocoenosis. The most productive crops and fertile territories were determined based on the seasonal and long-term dynamics of gross productivity. An increase in productivity for some agrocenoses was noted in 2018 according to satellite data.
Opportunities of short-term weather forecasts data in the environmental monitoring of the Kazakhstan
Authors: Terekhov Alexey , Abayev Nurlan , Bolatov Kainar , Egemberdyeva Zaure
Published: February 2020

This paper considers the possibilities of assimilation of FEWS NET (Famine early Warning System Network) products in natural resource monitoring of the territory of Kazakhstan in the cold period. With an area of 2.7 million km2, Kazakhstan is located in the center of Eurasia in the arid zone, and snow is one of the most important water sources in the first half of the vegetation season. The products “Snow Depth”, “Temperature” and “Precipitation” developed for Central Asia are based on model meteorological data, including short-term weather forecasts. This information, presented in the form of regular matrices, has several advantages in efficiency and spatial detailing over direct ground (remote) measurements of meteorological parameters. The use of FEWS NET products for the environmental monitoring of the entire territory of Kazakhstan or its separate parts is of benefit for assessing the current situation on snow reserves, weather regimes and prospects for spring snowmelt.
The effect of changing stratification in the atmosphere in central zone of Eurasia according to vegetation data of Tien Shan mountains during 2002-2019
Authors: Terekhov Alexey , Abayev Nurlan , Vitkovskaya Irina
Published: February 2020

On the basis of long-term dynamics of the July’s vegetation data (NDVI and VCI indices) for 31 ranges of the Tien Shan and Jungarian Alatau arid mountains located in the Eurasia center are found the atmosphere stratification change. The variability of Atlantic Ocean water vapor transport ability over Northern Tien Shan ranges to the Inner Tien Shan was detected. This phenomenon not related to the overall seasonal humidity but is obviously associated with atmosphere stratification regimes. The analyzed period consists of two eras from 2002–2008 and 2008–2019 years, which differ in the regime of accessibility of the Inner Tien Shan ranges for water vapor from Atlantic Ocean. The overall tendency of the changes in 2002–2019 is the increase in the availability ocean water vapor to the Inner Tien Shan ranges. Recorded changes may be due to global air temperature increases and atmospheric processes intensification.
Estimation of the vegetation diversity of the Western Tannu-Ola Range
Authors: Kuular Khulermaa B.
Published: February 2020

This paper discusses the main indicators diversity of vegetation in key areas of the northern macro slope of the Western Tannu-Ola Range. The degree of forest cover and vegetation fragmentation were estimated using Landsat-TM/ ETM+/OLI images for June 25, 1992, June 18, 1998 and June 24, 2015 in QGIS using the plugin Landscape Ecology. The Simpson index shows of increasing biodiversity in different altitudes. The results showed that with increasing climate warming in the region and maintaining this trend, the proportion of dark coniferous forest at all altitude levels (foothill, mid-elevation and high-elevation zones) will increase. And this led to a decrease in the fragmentation of the forest cover of northern macro slope of this range.
Dynamics of Changes in Long-Term Average Annual River Runoff in the Lake Sevan Basin
Authors: Margaryan Varduhi , Tsibul'skii Gennady , Raevich Ksenia
Published: February 2020

In the work, long-term fluctuations in the annual runoff of rivers flowing into lake Sevan were identified, analyzed and evaluated. As the source material, daily data of long-term actual instrumental observations of the annual runoff of rivers flowing into the lake, as well as air temperature and atmospheric precipitation of the lake basin for the entire observation period were used.
Performance evaluation of an adsorption refrigeration system powered by solar heat storage based on Moroccan irradiation
Authors: BOUSHABA Hicham , MIMET Abdelaziz , El GANAOUI Mohammed , MOURADI Abderrahman
Published: February 2020

The aim of this paperwork is to provide a performance comparative study of an adsorption refrigeration system powered by solar heat storage based on Moroccan irradiation. The system operates with ammonia as refrigerant and activated carbon as adsorbent. A parabolic through collector is used to collect the solar energy and store it in a heat storage tank. A dynamic simulation program interpreting the real behavior of the system has been developed. The pressure, temperature and adsorbed mass profiles in the Adsorber have been revealed. The system performance is estimated in terms of the specific cooling power (SCP) and the solar coefficient of performance (SCOP). The solar irradiation and the real ambient temperature variations corresponding to the six climatic zones in Morocco are considered. The effect of those conditions on the performance of the system has been investigated. The results show the capability of our system to realize more than one cycle and produce cold during the day. For an optimal configuration of the system and operating conditions of evaporation temperature, Tev=0 °C, condensation temperature, Tcon=30 °C and generation temperature, T3=100 °C, the process could achieve a SCP of 151 W.kg-1and its solar COP could attain 0.148. The system performances improve especially in sunny area.
Theoretical and experimental Investigation of Structural, electronic and optical properties of neodymium doped ZnO
Authors: Cherrad Hajar , Addou Mohammed , Hssein Mehdi , Bahedi Khadija , Jbilou Mohamed , Mrigal Asmaa , Salmani Elmehdi , Rouchdi Mustapha , Mezred Ahmed , Ftouhi Hajar , diani Mustapha , El Jouad Mohamed
Published: February 2020

The morphological and cathodoluminescent properties of Nd doped zinc oxide thin films deposited by reactive chemical pulverization spray pyrolysis technique on heated glass substrates at 450 °C are being reported. The films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and cathodoluminescent (CL) spectroscopy. We have also used the Generalised Gradient Approximation (GGA)-the Self Interaction Corrected (SIC) to determine Electronic structure and x ray absorption.
Evaluation of two earth–air heat exchangers efficiency of different pipe materials within a warm temperate climate
Authors: LEKHAL Mohammed Cherif , MOKHTARI Abderahmane Mejedoub , BELARBI Rafik
Published: February 2020

The Earth-Air Heat Exchanger (EAHE) system was used for many years for both primary heating and cooling applications, especially in the building sector. Its energy performance can be influenced by three principal factors: the EAHE pipe material, the airflow rate, the soil characteristics and the moisture content. The state of the art shows a divergence about the effect of the pipe material on the performance of the EAHE. The aim of this study is to provide an adequate response to this problematic based on experimental analysis. In this regard, we tested two EAHEX of different materials: PVC and Zinc. The comparative study was conducted under a warm temperate climate in the north of Algeria. The data analyses showed that the pipe material can significantly affect the EAHE performance during periods when the EAHE passes from heating to cooling mode. Furthermore, the air outlet temperature differences provided by EAHE Zinc and those of PVC up to about 7.5°C.
Temperature effect on structural and optical properties of V2O5 thin films prepared by spray pyrolysis technique
Authors: Mrigal Asmaa , El Gana Lahocine , Addou Mouhamed , Bahedi Khadija , Temsamani Rajae , Cherrad Hajar , El Jouad Zouhir , Zimou Jamal
Published: February 2020

In this work, the effect of substrate temperature on structural and optical properties of V2O5 thin films has been characterized by X-ray diffraction (XRD); SEM and transmission. The films mince has been prepared by Reactive Chemical Spraying technology in Liquid Phase (RCSLP) on glass substrates preheated at (350, 400, 450 and 500 °C). The X-ray diffraction analysis confirms that all layers are polycrystalline, and the preferred orientation of V2O5 is the (001) plane. The morphology of V2O5 thin films are porous nature and their particle’s shape is three-dimensional. The transmittance and absorbance of thin film were measured from which the optical constants (Energy gap, Refractive index, Absorption coefficient, Extinction coefficient and Optical dielectric constant) were determined.
Effect of Uniform and Non-Uniform Hot Wall Temperature on Species Separation in a Tilting Cell
Authors: Touiker Mouna , Omara Abdeslam
Published: February 2020

This work deals with the Soret separation of a binary liquid mixture (Water 60 wt %-Ethanol 40 wt %). The studied configuration is a tilted rectangular cavity of large aspect ratio A. It is assumed that the right wall is heated uniformly or non-uniformly, while the left wall is maintained at a constant cold temperature. The top and bottom walls are well insulated. A developed program (based on the finite-volume method and the semi-implicit method for pressure-linked equations algorithm) was utilized to numerically solve the governing Navier–Stokes equations, the energy and the species equations with the associated boundary conditions. The relevant parameters in this study are the tilting angle (α), the aspect ratio (A), the mass Rayleigh number (Ram) and the Lewis number (Le).
High accuracy infrared emissivity between 50 and 1000 ᵒC for solar materials characterization
Authors: Fuente Raquel , Echániz Telmo , González de Arrieta Iñigo , Urcelay-Olabarria Irene , Igartua Josu M , Tello Manuel J. , López Gabriel A.
Published: February 2020

The total hemispherical emissivity of materials used in the solar energy industry is a critical parameter in the calculation of the radiative thermal losses and material efficiency, especially in solar thermal collector absorbing surfaces. This is because the radiative heat losses have a significant economic impact on the final cost of the electricity produced in solar plants. Our laboratory, HAIRL, in the University of the Basque Country (UPV/EHU) in Spain [1] is the first to have published infrared spectral emissivity measurements in Solar Absorber Surfaces (SAS) at working temperature [2]. The laboratory allows measuring between 50 and 1000 ºC in the 0.83-25 μm range and is also capable of doing directional measurements at different angles between 0 and 80 degrees. Therefore, it is suitable for measuring solar selective coatings, for studying high temperature stability and for characterizing thermal energy harvesting materials. In this presentation, we show the specifications of our laboratory, the results of spectral emissivity measurements in air-resistant solar selective coatings and in eutectic alloys for thermal storage and we demonstrate the necessity of measuring at working temperature in order to possess reliable data.
Energetic valorization of used tires by pyrolysis: effect of catalysts on biofuel
Authors: Hiba Rejeb , Emna Berrich Betouche , Mohamed Hachemi Chahbani
Published: February 2020

Waste tires represent a disposal problem, environmental problem. To solve this problem and to upgrade this waste, several technologies are adopted such as pyrolysis. This technology produces a liquid that could replace other fuels. In this paper an experimental investigation is carried out to study the effect of the catalysts on biofuel. Two different percentages of catalysts have been used i.e. 10% and 20%. Experiments were carried out in a semi-batch reactor under atmospheric pressure. The properties of the products measured are the viscosity, the gross calorific value and the acid value. Identification of gas and liquid products is made by GC and GC-MS respectively. It is found that the waste tires allow obtaining a liquid yield equal 30.53 wt.% and is the same with 20% of the catalysts but it increases to 32.77 wt.% with 10% of catalysts. This liquid presents close characteristics to gasoline and kerosene.
Computational Study of Zigzag Spacer Design with Elliptical Cross-Section Filaments
Authors: Shoukat Gohar , Ellahi Farhan , Sajid Muhammad , Uddin Emad
Published: February 2020

The large energy consumption of membrane desalination process has encouraged researchers to explore different spacer designs using Computational Fluid Dynamics (CFD) for maximizing permeate per unit of energy consumed. In previous studies of zigzag spacer designs, the filaments are modeled as circular cross sections in a two-dimensional geometry under the assumption that the flow is oriented normal to the filaments. In this work, we consider the 45° orientation of the flow towards the three-dimensional zigzag spacer unit, which projects the circular cross section of the filament as elliptical in a simplified two-dimensional domain. OpenFOAM was used to simulate the mass transfer enhancement in a reverse-osmosis desalination unit employing spiral wound membranes lined with zigzag spacer filaments. Properties that impact the concentration polarization and hence permeate flux were analyzed in the domain with elliptical filaments as well as a domain with circular filaments to draw suitable comparisons. The range of variation in characteristic parameters across the domain between the two different configurations is determined. It was concluded that ignoring the elliptical projection of circular filaments to the flow direction, can introduce significant margin of error in the estimation of mass transfer coefficient.
Computational characterization of a Gurney flap on a DU91(2)W250 airfoil
Authors: Fernandez-Gamiz Unai , Errasti Iñigo , Zulueta Ekaitz , Lopez Guede José Manuel , Boyano Ana
Published: February 2020

The considerable increase of wind turbine rotor size and weight in the last years has made impossible to control as they were controlled 20 years ago. The cost of energy is an essential role to maintain this type of energy as a viable alternative in economic terms with traditional or other renewable energies. Through the last decades many different flow control devices have been developed. Most of them were shaped for aeronautical issues and this was its first research application. Currently researchers are working to optimize and introduce these types of devices in multi megawatt wind turbines. Gurney flap (GF) is a vane perpendicular to the airfoil surface with a size between 0.1 and 3% of the airfoil chord length, placed in the lower or upper side of the airfoil close to the trailing edge of the airfoil. When GFs are appropriately designed, they increase the total lift of the airfoil while reducing the drag. Thanks to the implementation of the of this flow control device the efficiency of a wind turbine improves, which results on an increase in the power generation.
A simplified protocol for in vitro rearing of human body lice
Authors: Pietri Jose E. , Ray Ritesh
Published: February 2020

Human body lice (Pediculus humanus) are neglected ectoparasites and pathogen vectors. Difficulties in raising and maintaining colonies of body lice in a laboratory setting remain a barrier to fundamental studies of physiology and vector-pathogen interactions in these insects. Several in vivo and in vitro rearing systems have been previously described and used by multiple research groups. However, these methods suffer from drawbacks that still complicate the rearing of body lice relative to many other commonly studied hematophagous insects. Here, a simplified protocol for raising and maintaining body lice in vitro using the commercially available Hemotek apparatus is described. This protocol draws from published methods for rearing body lice as well as other hematophagous insect species to further reduce labor, time, costs, and regulatory requirements typically associated with keeping human body lice in the laboratory. Using this protocol, the insects consistently fed on commercially available rabbit blood with little mortality, reached adulthood at a high rate, and produced a significant number of viable eggs, resulting in a 4.8-fold increase in population over a period of 40 days. The data suggest that the process described here can propagate modest populations for ongoing laboratory experiments and is a useful alternative to existing methods. The use and further optimization of in vitro rearing systems may facilitate dynamic studies of body lice by a wider range of investigators, enabling new progress in combating lice infestations, and louse-borne infections.
Hitzestress im Krankenhaus
Authors: Lenzer Benedikt , Drozdek Marija , Sosa Alvaro Valera , Matthys Stefanie , Witt Christian , Liebers Uta
Published: February 2020

Patienten mit chronischen Lungenkrankheiten sind von den Auswirkungen zunehmender Hitzewellen besonders betroffen, da die Lunge als „Grenzorgan zur Umwelt“ wirkt. COPD- und Asthma-Patienten reagieren mit verstärkter Bronchokonstriktion und stärkerer Entzündungsreaktion der Bronchialschleimhaut auf Hitzestress, was zur Symptomzunahme bis hin zur Hospitalisierung führen kann. Dies führt auch zu einem Anstieg der Mortalität.

Zur Prävention von Hitzestress im Krankenhaus können infrastrukturelle Anpassungen wie ein verbesserter Sonnenschutz oder das Anbringen von Kühldecken (konvektionsfreies Air Conditioning) vorgenommen werden. Ebenso können ein Monitoring der Flüssigkeitsaufnahme, körperliche Schonung und effektive Lüftungsregime Hitzestress abmildern. Im Falle Hitze-assoziierter Exazerbationen von COPD-Erkrankungen liegen erste Hinweise auf den therapeutischen Nutzen einer Krankenzimmer-Klimatisierung mit einer Raumtemperatur von 23° C vor. Hierfür bietet sich aufgrund energetischer und hygienischer Vorteile eine innovative Kühlung mithilfe konvektionsfreier Raumklimatisierung an. So könnte Patienten mit Hitze-assoziierter Krankheitsprogression ein ganzheitliches, über die traditionelle medikamentöse Therapie hinausgehendes, Behandlungskonzept angeboten werden.

Bei zukünftig häufigerem und intensiverem Hitzestress wird die Notwendigkeit präventiver Maßnahmen für Patienten mit chronischen Atemwegs-Krankheiten steigen. Zusätzlich wird für besonders vulnerable Gruppen der Bedarf an Raumklimatisierung steigen.
Sekundäre Neuroprotektion beim Glaukom durch Lebensstiländerungen
Authors: Rüfer Florian
Published: February 2020

Glaukompatienten wird neben der IOD-senkenden Therapie häufig eine gesunde Lebensweise empfohlen. Es wird dargestellt, wie diese definiert werden kann und welche sekundär neuroprotektiven Mechanismen dadurch angesprochen werden. Eine neuroprotektive Maßnahme liegt im Vermeiden von häufiger vorkommenden neurotoxischen Belastungen wie Zigarettenrauchen, Ethanol-, Methanol- oder Bleiintoxikationen. Die Ernährung sollte ausreichend abwechslungsreich sein und damit insbesondere einem Vitamin-B12- und Folsäuremangel vorbeugen. Durch eine Überernährung mit nachfolgendem metabolischem Syndrom kann es zu einer IOD-Erhöhung, zu einem arteriellen Hypertonus und zu einer erhöhten Steroidkonzentration kommen. Als weitere Folge kann das metabolische Syndrom zu einer eingeschränkten Nierenfunktion führen, wodurch neurotoxische Substanzen im Blut akkumulieren können. Sinnvoll sind vermehrte körperliche Ausdauerbelastungen zur Kalorienverbrennung und eine reduzierte Kalorienzufuhr. Als Gegenentwurf zur übermäßigen Kalorienzufuhr werden beim Fasten Ketonkörper wie Aceton, Acetoacetat und β-Hydroxybutyrat gebildet, denen durch eine zusätzliche Energieversorgung der Mitochondrien eine neuroprotektive Wirkung zugeschrieben wird. Eine ketogene Stoffwechsellage kann auch durch eine fettreiche Diät erreicht werden, die aber aufgrund der damit verbundenen kardiovaskulären Risiken nicht allgemein empfohlen werden kann. Durch Ausdauersport kann neben der Kalorienverbrennung eine Verminderung von Ängsten und Depressionen bewirkt werden, und es werden Neurotrophine mit einer ebenfalls neuroprotektiven Wirkung freigesetzt. Genetisch bedingte oder erworbene mitochondriale Dysfunktionen können gleichermaßen eine Rolle bei der glaukomatösen Optikusatrophie spielen. Insofern kann die Kenntnis sekundär neuroprotektiver Mechanismen durch eine kompetente Beratung der Patienten dazu beitragen, Risiken für den N. opticus zu minimieren und eine Homöostase der Stoffwechselprozesse am N. opticus wiederherzustellen.
MarkeTrak 10: History and Methodology
Authors: Powers Thomas A. , Rogin Carole
Published: February 2020

MarkeTrak has been conducted on a regular schedule for over 30 years to take the pulse of the hearing health care market and of consumers with hearing loss. The current version, MarkeTrak 10 (MT10), builds on the successful completion of MarkeTrak 9, with the same two objectives: to estimate hearing difficulty, hearing aid usage, and adoption of hearing aids in the United States and to gain insights into the consumer's journey through the hearing health care delivery system. In addition, MarkeTrak 10 added additional questions regarding use and satisfaction with Personal Sound Amplification Products (PSAPs) by both owners and nonowners of hearing aids.
Reconstruction and quantization of Riemannian structures
Authors: Majid Shahn
Published: February 2020

We use algebraic methods to obtain a Cartan-type formula ∇ωη=12(δ(ωη)−(δω)η+ωδη+ω ⊥ dη+dω ⊥ η+d(ω ⊥ η)) for the Levi−Civita connection on a classical Riemannian manifold M in the direction of a 1-form ω (i.e., the usual Levi−Civita connection along the corresponding vector field via the metric). Here, ⊥ denotes a degree −2 bidirectional interior product built from the metric and δ is the divergence or codifferential. We also recover that δ obeys a 7-term relation making the exterior algebra into a Batalin−Vilkovisky algebra. These formulas arise naturally from a novel view of Riemannian structures as cocycles governing the central extension of the classical exterior algebra to a quantum one, motivated by ideas for quantum gravity. The approach also works when the initial exterior algebra is already quantum, allowing us to construct examples of quantum Riemannian structures, including quantum Levi−Civita connections, as cocycle data. Combining with the semidirect product of a differential graded algebra by the quantum differential algebra Ω(t, dt) in one variable, we recover a differential quantization of M×R associated to any conformal Killing vector field on a Riemannian manifold M.
Effects of intrinsic and atmospherically induced defects in narrow bandgap (FASnI3)x(MAPbI3)1−x perovskite films and solar cells
Authors: Subedi Biwas , Li Chongwen , Junda Maxwell M. , Song Zhaoning , Yan Yanfa , Podraza Nikolas J.
Published: February 2020

Narrow bandgap mixed tin (Sn) + lead (Pb) perovskites are necessary for the bottom sub-cell absorber in high efficiency all-perovskite polycrystalline tandem solar cells. We report on the impact of mixed cation composition and atmospheric exposure of perovskite films on sub-gap absorption in films and performance of solar cells based on narrow bandgap mixed formamidinium (FA) + methylammonium (MA) and Sn + Pb halide perovskites, (FASnI3)x(MAPbI3)1−x. Structural and optical properties of 0.3 ≤ x ≤ 0.8 (FASnI3)x(MAPbI3)1−x perovskite thin film absorbers with bandgaps ranging from 1.25 eV (x = 0.6) to 1.34 eV (x = 0.3) are probed with and without atmospheric exposure. Urbach energy, which quantifies the amount of sub-gap absorption, is tracked for pristine perovskite films as a function of composition, with x = 0.6 and 0.3 demonstrating the lowest and highest Urbach energies of 23 meV and 36 meV, respectively. Films with x = 0.5 and 0.6 compositions show less degradation upon atmospheric exposure than higher or lower Sn-content films having greater sub-gap absorption. The corresponding solar cells based on the x = 0.6 absorber show the highest device performance. Despite having a low Urbach energy, higher Sn-content solar cells show reduced device performances as the amount of degradation via oxidation is the most substantial.
Effects of surface charge and cluster size on the electrochemical dissolution of platinum nanoparticles using COMB3 and continuum electrolyte models
Authors: Goff James M. , Sinnott Susan B. , Dabo Ismaila
Published: February 2020

We study the site-dependent dissolution of platinum nanoparticles under electrochemical conditions to assess their thermodynamic stability as a function of shape and size using empirical molecular dynamics and electronic-structure models. The third-generation charge optimized many-body potential is employed to determine the validity of uniform spherical representations of the nanoparticles in predicting dissolution potentials (the Kelvin model). To understand the early stages of catalyst dissolution, implicit solvation techniques based on the self-consistent continuum solvation method are applied. It is demonstrated that interfacial charge and polarization can shift the dissolution energies by amounts on the order of 0.74 eV depending on the surface site and nanoparticle shape, leading to the unexpected preferential removal of platinum cations from highly coordinated sites in some cases.
Separation of chaotic signals by reservoir computing
Authors: Krishnagopal Sanjukta , Girvan Michelle , Ott Edward , Hunt Brian R.
Published: February 2020

We demonstrate the utility of machine learning in the separation of superimposed chaotic signals using a technique called reservoir computing. We assume no knowledge of the dynamical equations that produce the signals and require only training data consisting of finite-time samples of the component signals. We test our method on signals that are formed as linear combinations of signals from two Lorenz systems with different parameters. Comparing our nonlinear method with the optimal linear solution to the separation problem, the Wiener filter, we find that our method significantly outperforms the Wiener filter in all the scenarios we study. Furthermore, this difference is particularly striking when the component signals have similar frequency spectra. Indeed, our method works well when the component frequency spectra are indistinguishable—a case where a Wiener filter performs essentially no separation.
Modulation of the optical absorption edge of ε- and κ - Ga2O3 due to Co impurities caused by band structure changes: Work function measurements and first-principle calculations
Authors: Yamanaka K. , Raebiger H. , Mukai K. , Shudo K.
Published: February 2020

Despite a wide bandgap of 4.8 eV, Ga2O3 has good electrical conductivity and thus has a wide range of potential applications. We previously reported that the bandgap of ϵ-Ga2O3 is widened by Co-doping; here, we present a theoretical discussion of the changes in the electronic state induced by Co impurities. By comparing calculated and experimental absorptions, the experimentally observed optical bandgap was assigned to a transition from a bulk peak (1.0 eV below the valence band maximum) to the conduction band minimum. The photoabsorption of Ga2O3:Co is not readily explained simply in terms of the bandgap of Ga2O3. However, the adjustable shift of the cutoff in its photoabsorption spectrum can be explained in terms of midgap impurity levels due to Co-doping, while the bandgap of Ga2O3 was almost unchanged even when the Co-impurity concentration was high. In addition, the work function, which was determined experimentally by photoemission spectroscopy, increased with the content of Co impurities. This was attributed to a lowering of the Fermi level induced by Co-doping.
Numerical treatment for three-dimensional rotating flow of carbon nanotubes with Darcy–Forchheimer medium by the Lobatto IIIA technique
Authors: Nagoor Afnan Hossain , Alaidarous Eman Salem , Sabir Muhammad Touseef , Shoaib Muhammad , Raja Muhammad Asif Zahoor
Published: February 2020

In this study, numerical treatment with the Lobatto IIIA technique is presented to analyze the dynamics of Darcy–Forchheimer flow for carbon nanotubes (CNTs) in a revolving frame. Stretching the surface causes fluid flow and the model is implemented for the transport of hybrid nanofluids. The governing partial differential system is simplified with the involvement of the boundary layer approximation. Similarity variables are used for the transformation of governing partial differential equations into a system of nonlinear ordinary differential equations. The results for single and multiwalled CNTs are attained by the Lobatto IIIA technique for the analysis of the resulting system. Adequate numerical and graphical illustrations are presented to investigate and understand how different flow parameters affect the velocities and temperature fields. Furthermore, the coefficients of the skin friction and the local Nusselt number are inspected numerically.
Microwave interferometer for phase and response time measurements
Authors: Nobles J. E. , Hankiewicz J. , Bueno Baques D. , Celinski Z.
Published: February 2020

We report the development of a microwave interferometer using a quadrature intermediate frequency (IQ) mixer designed to measure the relative phase change and response time of microwave devices tested in the Ka and upper K bands (22–40 GHz). The interferometer is currently used to test liquid crystal based devices. The system allows for the application of an AC bias beyond the amplitude/frequency limitations imposed on vector network analyzer bias ports. Our IQ mixer based design uses bias signals ranging from 0 to 100 V peak-to-peak in a frequency range from DC to 100 kHz. This range of bias signals is necessary to properly test the response of microwave devices designed with liquid crystal materials. The setup enables us to measure changes in the output phase of the device as a function of both the voltage and frequency of the applied bias signal. The setup also measures the phase difference as a function of microwave frequency and response times for the device under test. Our system can be integrated into a stand-alone test setup without the need for a vector network analyzer.
How does stiffness of polymer chains affect their adsorption transition?
Authors: Milchev A. , Binder K.
Published: February 2020

The adsorption transition and the structure of semiflexible adsorbed macromolecules are studied by a molecular dynamics simulation of a coarse-grained, bead-spring type model. Varying chain length N and stiffness κ (which is proportional to the persistence length ℓp in d = 3 dimensions) as well as the strength ϵwall of the adsorption potential, the adsorbed monomer fraction, orientational bond order parameter, and chain linear dimensions are studied. In the simulations, excluded volume interactions normally are included but can be “switched off,” and thus, the influence of excluded volume (leading to deviations from predictions of the wormlike chain model) can be identified. It is shown that the variation in the adsorption threshold ϵwallcr with ℓp is compatible with the predicted law ϵwallcr∝ℓp−1/3. In the vicinity of the adsorption threshold, the coils are still three-dimensional, and for large ℓp, the effect of the excluded volume is almost negligible, while for strongly adsorbed chains it is always felt. Near the transition, the decay length of orientational correlations along the chain contour increases gradually from ℓp to 2ℓp. While the latter value is expected for strictly two-dimensional chains from the Kratky–Porod model, this model is inaccurate for the description of lateral chain dimensions of long, strongly adsorbed, semiflexible polymers due to its neglect of excluded volume. The significance of these findings for the interpretation of pertinent experiments is briefly discussed.
Nitride tuning of transition metal perovskites
Authors: Fuertes Amparo
Published: February 2020

Transition metal perovskite oxynitrides are emergent materials for applications as visible light-active photocatalysts for water splitting and CO2 reduction and as thermoelectric, dielectric, and magnetic materials. They have been reported for early transition metals Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W in the B sites and alkaline earth or rare earth metals in the A sites. Nitrogen is less electronegative and more polarizable than oxygen, and nitride is more charged than oxide. As a consequence, the introduction of nitride in an oxidic perovskite has important effects on the covalency of bonds, the energy of electronic levels, and the valence states of the cations. This work discusses fundamental and recent developments of perovskite oxynitrides of transition metals of groups 4, 5, and 6 as photocatalytic and electronic materials, focusing on the important aspects of synthetic methodologies, crystal structures, and anion ordering, in connection with the observed physical and chemical properties. Some examples of compounds with late transition metals and complex structures such as layered and double perovskites are also discussed.
Assessing the roles of Cu- and Ag-deficient layers in chalcopyrite-based solar cells through first principles calculations
Authors: Sharan Abhishek , Sabino Fernando P. , Janotti Anderson , Gaillard Nicolas , Ogitsu Tadashi , Varley Joel B.
Published: February 2020

Chalcopyrites are a demonstrated material platform for realizing efficient thin-film photovoltaics, with the most well known Cu(In,Ga)Se2 (CIGS)-based solar cells exceeding 23%. Several factors, including flexibility in tuning the absorber bandgap, enhanced surface treatments, and the electrically benign nature of common defects are responsible for the existing high performance and future promise in chalcopyrite-based photovoltaic devices. The introduction of Cu-poor phases (also known as ordered-vacancy compounds or OVCs) between the absorber and buffer layers in CIGS solar cells is known to enhance device performance; however, the overall properties and role of OVCs remain poorly understood. Using first principles calculations based on the density functional theory with screened hybrid functionals, we explore the electronic structure and stability of OVCs and their band offsets with defect-free chalcopyrite layers in Cu- and Ag-based compounds (ABX2 where A=Cu, Ag; B=In, Ga, Al; and X=S, Se). Using AB3X5 and AB5X8 stoichiometries as model OVC systems, we report on the variation of the bandgap with the A/B ratio and discuss the trends in other Cu- and Ag-based chalcopyrites beyond CuInSe2. We find that the valence and conduction bands are lower in energy in OVCs with respect to the parent ABX2 chalcopyrite owing to a reduced p–d interaction between X and A atoms. We additionally perform device-level simulations to assess the implications of the results, finding that the valence band offsets of OVCs are favorable, while the conduction band offsets of chalcopyrites beyond CuInSe2-based absorbers may be detrimental in conventional solar cell device designs.
Anisotropic particles in two-dimensional convective turbulence
Authors: Calzavarini Enrico , Jiang Linfeng , Sun Chao
Published: February 2020

The orientational dynamics of inertialess anisotropic particles transported by two-dimensional convective turbulent flows display a coexistence of regular and chaotic features. We numerically demonstrate that very elongated particles (rods) align preferentially with the direction of the fluid flow, i.e., horizontally close to the isothermal walls and dominantly vertically in the bulk. This behavior is due to the presence of a persistent large scale circulation flow structure, which induces strong shear at wall boundaries and in up/down-welling regions. The near-wall horizontal alignment of rods persists at increasing the Rayleigh number, while the vertical orientation in the bulk is progressively weakened by the corresponding increase in turbulence intensity. Furthermore, we show that very elongated particles are nearly orthogonal to the orientation of the temperature gradient, an alignment independent of the system dimensionality and which becomes exact only in the limit of infinite Prandtl numbers. Tumbling rates are extremely vigorous adjacent to the walls, where particles roughly perform Jeffery orbits. This implies that the root-mean-square near-wall tumbling rates for spheres are much stronger than for rods, up to O(10) times at Ra ≃ 109. In the turbulent bulk, the situation reverses and the rods tumble slightly faster than isotropic particles, in agreement with earlier observations in two-dimensional turbulence.
In-plane quartz-enhanced photoacoustic spectroscopy
Authors: Ma Yufei , Qiao Shunda , Patimisco Pietro , Sampaolo Angelo , Wang Yao , Tittel Frank K. , Spagnolo Vincenzo
Published: February 2020

An optical gas sensing technique based on in-plane quartz-enhanced photoacoustic spectroscopy (IP-QEPAS) is reported. In IP-QEPAS, the laser beam is aligned in the plane of the quartz tuning fork (QTF) to increase the interaction area between the acoustic wavefront and the QTF. A custom T-shaped QTF with a prong length of 9.4 mm and a resonance frequency of 9.38 kHz was designed and employed in the IP-QEPAS sensor. For comparison, the traditional QEPAS sensor in which the laser beam is perpendicular to the QTF plane (PP-QEPAS) is investigated with the same operating conditions. Theoretical calculations of strain and displacement of the QTF prong were performed to support the advantage of using the IP-QEPAS technique. By selecting water vapor as the gas target, the IP-QEPAS sensor results in a signal more than 40 times higher than that measured with the PP-QEPAS configuration, confirming the potential of this approach.