bluuebunny/crossref_metadata_2025 huggingface dataset:
Turbidity and oil removal from oilfield produced water, middle oil company by electrocoagulation technique
Authors: Mohammed Thamer , Abbas Esraa , Ahmed Thabit
Published: May 2018

Huge quantity of produced water is salty water trapped in the oil wells rock and brought up along with oil or gas during production. It usually contains hydrocarbons as oil and suspended solids or turbidity. Therefore the aim of this study is to treat produced water before being discharge to surface water or re injected in oil wells. In this paper experimental results were investigated on treating produced water (which is obtained from Middle Oil Company-Iraq), through electrocoagulation (EC). The performance of EC was investigated for reduction of turbidity and oil content up to allowable limit. Effect of different parameters were studied; (pH, current density, distance between two electrodes, and electrolysis time). The experimental runs carried out by an electrocoagulation unit was assembled and installed in the lab and the reactor was made of a material Perspex, with a capacity of approximately 2.5 liters and dimensions were 20 cm in length, 14 cm in width and 16 cm height. The electrodes employed were made of commercial materials. The anode was a perforated aluminum rectangular plate with a thickness of 1.72 mm, a height of 60 mm and length of 140 mm and the cathode was a mesh iron. The current was used in the unit with different densities to test the turbidity removing efficiency (0.0025, 0.00633, 0.01266 and 0.0253 A/cm2).The experiment showed that the best turbidity removing was (10, 9.7, 9.2, 18 NTU) respectively. The distance between the electrodes of the unit was 3cm. The present turbidity removing was 92.33%. A slight improvement of turbidity removing was shown when the distance between the electrodes was changed from 0.5 to 3 cm with fixation of current density. The best turbidity removing was 93.5% , (7.79 NTU) when the distance between the electrodes were 1 cm. The experimental results found that concentration of oil had decreased to (10.7, 11.2, 11.7, 12.3) mg/l when different current densities (0.00253, 0.00633, 0.01266, 0.0253) A/cm2 were used, respectively with the distance between the electrodes was 3 cm. The best result of oil content decreasing was 10.7 mg/l with current density 0.0253 A/cm2. These results are within allowable limit to provide the possibility of reuse the water and can be injected in oil wells
Production of fuel gases from reed by using downdraft gasifier
Authors: Al-Obaidy Abdul-Hameed , Al-Anbari Riyad , Kazim Hussein
Published: May 2018

This study was conducted to investigate the ability of reed as a Production of gases via gasification technique by using special gasifier made for this purpose and to evaluate the produced gases (CO, H2, CO2 and CH4). The results showed that the percentage of production gases was 15.6%, 10.2%, 7.81% and 1.69% for carbon monoxide, carbon dioxide, hydrogen and methane respectively. In addition, it showed that the highest temperature up to the gasifier was 700°C and the time required to complete gasification process was 23 min. The results indicated that 5 kg of reed was capable of producing 10 m3 of gases which produces about 1 HP-hr. that equivalent to 3.75 kWh.
Assessment of pollution in water quality of oil and grease for Tigris River-Iraq by GIS mapping (2010-2016)
Authors: Mawlood Ibtihal , Ziboon Abdul-Razzak , Al-Obaidy Abdul-Hammed
Published: May 2018

In this study have followed the oils and grease in Tigris River within Baghdad city during the period 2010-2015 by using ArcGIS 10.2 program. Two satellite image of each year were used which were taken in as same time as collected samples and painted the mapping which show the locations of pollution the river by oil and grease. This study showed the Tigris river is pollution by the oil and grease, and the values were up limit allowable depend on the world health organization (who) and Iraqi criteria.
Evaluation of raw water quality in Wassit governorate by Canadian water quality index
Authors: Mahmood Abdulkhaleq
Published: May 2018

In this work an attempt has been done to evaluate the raw water quality in Wassit Governorate by using Canadian Council of Ministers of Environment Water Quality Index (CCME WAI). Six stations along Tigris River were located and the field work was conducted during one year from October 2015 to September 2016 in collecting data. Twelve water parameters were used to evaluate the water quality index (pH, turbidity, total dissolved solid, total alkalinity, total hardens, nitrate, calcium, sodium, potassium, magnesium, chloride, and sulfate). The raw water quality in Wassite Governorate has been ranged between (65-79) based on CCME WQI results, which means that the river has not been in its good condition, and need to be manage to control the sources of pollutants by monitoring to keep them in their natural condition.
Pollution assessment of Euphrates River in three governances of Iraq
Authors: Al-Fatlawi Alaa , Al-Jassani Mohammed , Al-Rifaie Jawad
Published: May 2018

This study was concerned with assessment the water quality of Euphrates River in the middle of Iraq. Water quality assessment is the overall process of evaluation of the physical, chemical and biological nature of the water. Water pollution for Euphrates River in Middle of Iraq (Babylon, Al-Najaf, and Al-Diwaniya governorates) occurs in both rural and urban areas. In rural areas, drinking water from natural sources such as rivers and streams is usually polluted by organic substances from upstream users who use water for agricultural activities. To protect the water resources from pollution and deterioration which caused by natural pollutants or human activities, an environmental database was constructed and applied. A Visual Basic (version 6.0) Software program was constructed to evaluate the pollutant concentrations using regression models obtained by Data Fit Software program (version 8.0) to make the monitoring system. The result of the program is verified with data of year 2008 which is not included in regression model. This verification shows a good agreement with coefficient of determination ranged between “0.914 to 0.994”To assess water body for compliance with standards that have been set to define requirements for various functions and uses, the water body concerned, were compared with the Iraqi, and WHO standards for domestic and irrigation purposes, for determining whether water quality at sampling sites exceeds water quality standards. A comparison shows that these parameters in some stations are within the Iraqi and WHO standards (i.e. total dissolved solids (TDS): in Al-Musaib, Al-Kufa, Al-Shamya station), and (calcium (Ca): in Al-Hindya Barrage station).
Effect of urban geometry and green area on the formation of the urban heat island in Baghdad city
Authors: Mohammed Younis , Salman Aws
Published: May 2018

With the growth of cities, the ambient air temperatures (Ta) inside the urban areas are expected to be higher compared to the surrounding rural areas, creating urban heat island (UHI) phenomenon. The city of Baghdad is an example of a hot dry climate cities and during summer, the UHI intensity is significantly affected by the extreme direct solar radiation and leads to outdoor thermal discomfort. Also it causes an increase in energy consumption and air pollution. This research work focuses on the effect of urban geometry and green area in the formation of heat island through a study of two different fabrics of residential neighbourhoods. The height to width ratio (H/W) and vegetation are adopted while the materials of buildings were unified in all study cases. Three-dimensional numerical software Envi-met 4.1 was utilized to analyze and assess the studied parameters including: ambient air temperature (Ta), street surface temperature (Ts) and mean radiant temperature (Tmrt). This study has given a better understanding of the role of urban geometry and green area on forming the UHI that influence on the microclimatic conditions in hot dry climate of the city of Baghdad. So that helped to generate guidelines of urban design and planning practices for a better thermal performance in hot and dry cities.
Green technologies in sustainable urban planning
Authors: Laffta Suaad , Al-rawi Areaj
Published: May 2018

The world is facing many environmental and economic problems resulting from rapid urbanization and over-exploitation of available resources as well as due to the dramatic increase of the population and corresponding increases in the number of cities. Technological and industrial development plays a big role in these problems. As a result, the term green technology became as a tool to solve these problems with an orientation towards sustainable development at all levels. , It seems to be very effective tool in modern urban planning which incorporates of all aspects of planning such as infrastructure and industry, energy, telecommunications, transportation and other vital areas in cities. These technologies are environment friendly inventions that often involve - energy efficiency, recycling, safety and health concerns, renewable resources, and more. Green technologies include several forms of technology that help to minimize negative effects on the environment and create new ways to achieve sustainable development. This paper is about green technology and its role in sustainable urban planning, it aims to clarify the most important areas for the application of this technology and the benefits provided by these technologies in improving the lives of the population in cities and a development orientation towards sustainability.
Anwendung von Vakuum-Wundtherapie bei Spalthaut-Transplantaten im Kopf-Hals-Bereich
Authors: Thierauf Julia , Wiggenhauser Paul Severin , Hoffmann Thomas Karl , Greve Jens , Scheithauer Marc , Veit Johannes Adrian
Published: May 2018

Hintergrund Bei der Vakuum-Wundtherapie (VAC) wird durch einen Unterdruck Wundsekret kontinuierlich abgesaugt und so die Bildung von Granulationsgewebe
signifikant gesteigert. Im Bereich der Viszeral-, Unfall- und Verbrennungschirurgie kommt diese bei kritischen Wunden häufig zum Einsatz. Im Kopf-Hals-Bereich
gibt es wenige Publikationen und begrenzte Erfahrungen. Insbesondere zur Anwendung des VAC-Systems bei Spalthaut-Transplantation (SHT) liegt bislang keine
Evidenz vor.

Material und Methoden Eine retrospektive Datenbankrecherche ergab insgesamt 36 VAC Anwendungen bei 13 Patienten, die über den Zeitraum von 2012 bis 2017
an der HNO-Universitätsklinik Ulm behandelt wurden. Es erfolgte eine Analyse der Indikationen, klinischen Verläufe und des Outcomes der VAC-Therapie mit Fokus
auf die Anwendung im Rahmen einer SHT.

Ergebnisse Neben den klassischen Indikationen wie pharyngo-cutanen Fisteln oder Wundheilungsstörungen nach Lappenchirurgie, konnten 7 Fälle von
VAC-Anwendung bei Spalthaut-Transplantation identifiziert werden. Die mediane VAC-Behandlungsdauer lag bei 11 Tagen, der VAC-Verband wurde im mittel 2-mal
gewechselt, der Sog lag durchschnittlich bei 70 mmHg. Der Wundverschluss war in 13/13 Fällen erfolgreich, in 7/13 Fällen wurde der definitive Wundverschluss
durch SHT mit synchronem Anbringen eines VAC-System erreicht, in 4/13 Fällen führte die Sekundärheilung zum Wundverschluss und in 2/13 Fällen war eine Nah- bzw.
Fernlappenplastik erforderlich.

Schlussfolgerungen Die VAC-Therapie scheint bei prolongierten Wundheilungsverläufen im Kopf-Hals-Bereich eine effektive Therapie darzustellen. Die hier
erstmals beschriebene SHT unter VAC-Therapie führt zu hohen Erfolgsraten insbesondere bei vorbestrahlten Patienten oder dem Krankheitsbild der nekrotisierenden
Fasziitis und ersetzt zusätzlich den Druckverband.
Remote Oxidative C–H Amidation of Anilides with Dibenzenesulfonimides under Metal-Free Conditions
Authors: Zhang Qian , Li Dong , Xiang Dehu , Xia Lan , Zhang Yunhua
Published: May 2018

A remote oxidative C–H bond amidation of anilides with dibenzenesulfonimides mediated by PhI(OAc)2 under metal-free conditions provided para-amidated anilides with high selectivity and moderate to good yields. The reaction proceeded under mild or neutral conditions and it has good air and moisture tolerance. The method represents a novel and facile strategy for the synthesis of arylamines.
Artificial Macrocycles
Authors: Abdelraheem Eman , Shaabani Shabnam , Dömling Alexander
Published: May 2018

Artificial macrocycles recently became popular as a novel research field in drug discovery. As opposed to their natural twins, artificial macrocycles promise to have better control on synthesizability and control over their physicochemical properties resulting in druglike properties. Very few synthetic methods allow for the convergent, fast but diverse access to large macrocycles chemical space. One synthetic technology to access artificial macrocycles with potential biological activity, multicomponent reactions, is reviewed here, with a focus on our own work. We believe that synthetic chemists have to acquaint themselves more with structure and activity to leverage the design aspect of their daily work.

1 Introduction

2 Macrocycle Properties and Receptor Binding

3 Synthetic Approaches towards Artificial Macrocycles Using MCR

4 Design Rules for Membrane Crossing Macrocycles

5 Design Rules for Libraries of Macrocycles

6 Computational Macrocyclic Methods

7 Future View
Endovascular Treatment of Various Aortic Pathologies: Review of the Latest Data and Technologies
Authors: Ohki Takao , Kanaoka Yuji , Maeda Koji
Published: May 2018

The technologies and innovations applicable to endovascular treatment for complex aortic pathologies have progressed rapidly over the last two decades. Although the initial outcomes of an endovascular aortic repair have been excellent, as long-term data became available, complications including endoleaks, endograft migration, and endograft infection have become apparent and are of concern. Previously, the indication for endovascular therapy was restricted to descending thoracic aortic aneurysms and abdominal aortic aneurysms. However, its indication has expanded along with the improvement of techniques and devices, and currently, it has become possible to treat pararenal aortic aneurysms and Crawford type 4 thoracoabdominal aortic aneurysm (TAAA) using the off-the-shelf devices. Additionally, custom-made devices allow for the treatment of arch or more extensive TAAAs. Endovascular treatment is applied not only to aneurysms but also to acute/chronic dissections. However, long-term outcomes are still unclear. This article provides an overview of available devices and the results of endovascular treatment for various aortic pathologies.
An N-of-1 Feasibility Study of Homeopathic Treatment for Fatigue in Patients Receiving Chemotherapy
Authors: Balon Jeffrey , Zhao Linlu , Seely Dugald , Brulé David
Published: May 2018

Background Cancer-related fatigue has been described as a subjective feeling of physical, emotional, and/or cognitive tiredness. Homeopathy has been widely used to treat side effects of chemotherapy. The n-of-1 design is a single-patient trial method to study a clinical condition that is either short lived and reversible or is chronic and stable. The n-of-1 design requires a washout/reset period. The feasibility of performing an n-of-1 study in homeopathy has not previously been tested.

Methods A feasibility n-of-1 trial of individualized homeopathic treatment for fatigue in a single adult undergoing chemotherapy administered periodically was performed. For each matched pair of treatments, the participant was randomly allocated either placebo or verum for the period between treatments. For the subsequent treatment period, the opposite allocation was given. Participant and practitioner were blinded to the allocation. Ongoing conventional treatments were permitted. The ability to recruit and retain was monitored and changes in fatigue and quality of life were measured using two validated outcome measures.

Results Sixty-eight patients were assessed between February 2014 and February 2015. Four patients were eligible for the study and one consented to participate. The participant enrolled in the study for six cycles of chemotherapy and completed all treatment and outcome measures. There was no improvement under homeopathic treatment compared to placebo. There were multiple confounding events such as conventional medication changes and an adverse event unrelated to therapy.

Conclusion Adequate recruitment was not feasible in this setting. The n-of-1 study design is feasible in this population from the perspective of the ability to complete the trial. No conclusion on the efficacy of homeopathy for this individual can be made. It is unclear as to whether multiple treatments of chemotherapy would be an appropriate clinical situation in which to apply the n-of-1 trial methodology. Future studies should pilot adaptations to this study design.
Intravenous Acetaminophen May Be Associated with Reduced Odds of 30-Day Readmission after Total Knee Arthroplasty
Authors: Mont Michael , Lovelace Belinda , Pham An , Hansen Ryan , Chughtai Morad , Gwam Chukwuweike , Khlopas Anton , Barrington John
Published: May 2018

The purpose of this study was (1) to evaluate 30-day readmission rates in total knee arthroplasty (TKA) patients who either received intravenous (IV) or oral (PO) acetaminophen (APAP) perioperatively and (2) to extrapolate the potential annual cost savings on the national level. This was a review of 190,691 TKA recipients between the years 2012 and 2015 who received either IV (n = 56,475) or PO APAP (n = 134,216). All-cause readmissions that occurred between patient discharge and 30 days postdischarge were recorded. Continuous and categorical variables were evaluated using t-test and chi-square test, respectively. A logistic regression analysis was conducted to assess the effect of IV APAP on 30-day readmission. We also performed a literature review on 30-day readmission rates and risk prediction tools for TKA and correlated these with our findings. In addition, we extrapolated potential cost savings on the national level. The readmission rate was 0.04% in the IV and 0.14% in the PO APAP cohort (69% decreased risk; odds ratio = 0.31; 95% confidence interval = 0.20–0.47; p < 0.001). The readmission rate in this patient population appears to be markedly lower, when compared with previous reports. This reduction in readmissions may potentially result in $160 million savings per year. The use of IV APAP in TKA patients resulted in lower readmission rates, which may be valuable in clinical decision making by surgeons and health care administrators looking to lower costs of care.
TDABC Cost Analysis of Ocular Disorders in an Ophthalmology Emergency Department versus Urgent Care: Clinical Experience at Massachusetts Eye and Ear
Authors: Chou Jonathan , Shah Mahek , Watts Amy , Gardiner Matthew , Kaplan Robert , Miller Joan , Loewenstein John
Published: May 2018

Purpose To perform a cost analysis comparison for managing common ocular disorders in an eye emergency department (ED) versus an urgent care setting using a time-driven activity-based cost model (TDABC) to assist physicians and staff in appropriate allocation of resources at their own institution.

Design Retrospective analysis.

Setting Massachusetts Eye and Ear (MEE) ED and Same-Day Services (SDS), which runs as an urgent care clinic.

Population Patients diagnosed with corneal abrasions, dry eyes, conjunctivitis, and styes were identified between April 2014 and August 2015 (n = 2,408 [ED], 26 [SDS]). We determined resources used in delivery of care, which included personnel, consumables, space capacity, and equipment. Costs were identified based on time the patient spent with each resource.

Main Outcome Average visit length and associated personal, space, equipment, and consumable costs.

Results Average visit length was 196 and 53 minutes, respectively, primarily due to longer wait times in the ED. Personnel and space costs were higher in the ED compared with SDS ($68.92 vs. $51.37 and $24.44 vs. $12.86, respectively). This led to an overall higher total resource cost for patients seen in the ED compared with SDS ($108.41 vs. $81.53, respectively).

Conclusion For common ocular disorders, total SDS costs were 25% less than ED costs at MEE primarily due to personnel and space utilization. Treating patients with nonemergent ocular problems outside the ED can lead to shorter visit times for patients as well as lower overall costs.
The Efficacy of Neutral Position Beractant Administration in Neonates
Authors: Barnes Kelsi , Beckett Robert , Rice Melissa , Kovey Karen
Published: May 2018

Objective The objective was to compare the efficacy and adverse effects of beractant administration in neonates via a single aliquot in a neutral position versus positioning the neonates on their left then right side and two aliquots administration.

Study Design This was a retrospective cohort chart review of neonates who were diagnosed with respiratory distress syndrome and received beractant during two 15-month periods between 2013 and 2015 and 2015 and 2016 to compare the change in the fraction of inspired oxygen (FiO2) 1 hour after beractant administration.

Results There were no differences in FiO2 1 hour after beractant between groups (p = 0.617). Adverse events and other comorbidities did not differ between the groups.

Conclusion Changing administration of beractant from two aliquots and positions to a neutral position resulted in no significant change in FiO2 and may be considered as an option for administration in neonates.
Hepatoprotective Potential of Elsholtzia densa Against Acute and Chronic Models of Liver Damage in Wistar Rats
Authors: Zargar Ovais , Bashir Rohina , Ganie Showkat , Masood Akbar , Zargar Mohammad , Hamid Rabia
Published: May 2018

The aim of the present study was to evaluate the hepatoprotective activity of methanolic extract of Elsholtzia densa against experimentally induced acute (CCl4) and chronic (paracetamol) liver injury in albino wistar rats. Activity was measured by monitoring the serum levels of ALT, ALP AST and LDH, total protein levels, bilirubin and albumin. The results of the CCl4 and paracetamol-induced liver toxicity experiments showed that the rats treated with the methanolic extract of Elsholtzia densa exhibited a significant decrease in biochemical parameters as well as the proteins, which were all elevated in the CCl4 and paracetamol group. The extract at a concentration of 300 mg/kg body wt. showed a significant decline (P≤0.05) in the levels of AST, ALT, ALP and LDH to 69.50±2.23IU/L, 60.01±2.25IU/L,46.20±2.24 IU/L and 150.21±5.68IU/L in CCl4 injected animals and 51.12±2.20 IU/L,49.15±3.25 IU/L, 44.12±2.56 IU/L and 125.15±4.45 IU/L in paracetamol-treated animals when compared to the control group. The activities of tissue antioxidants GSH, GPx, GR, GST and CAT was significantly (P≤0.05) restored in dose dependent manner in animals treated with extracts as with acute and chronic hepatotoxic models. The current study confirmed the hepatoprotective effect of methanolic extract of Elsholtzia densa against the model hepatotoxicant CCl4 and paracetamol.
11.361 sports injuries in a 15-year survey of a Level I emergency trauma department reveal different severe injury types in the 6 most common team sports
Authors: Krutsch Werner , Krutsch Volker , Hilber Franz , Pfeifer Christian , Baumann Florian , Weber Johannes , Schmitz Paul , Kerschbaum Maximilian , Nerlich Michael , Angele Peter
Published: May 2018

Introduction Severe sports-related injuries are a common affliction treated in Level I trauma departments. Detailed knowledge on injury characteristics from different medical settings is essential to improve the development of injury prevention strategies in different team sports.

Methods Team sport injuries were retrospectively analysed in a Level I trauma department registry over 15 years. Injury and treatment data were compared with regard to competition and training exposure. Injury data such as “time of visitation”, “type of injury”, “multiple injured body regions” and “immediate hospitalisation” helped to define the severity level of each team sports injury.

Results At the Level I trauma department, 11.361 sports-related injuries were seen over 15 years, of which 34.0 % were sustained during team sports. Soccer injuries were the most common injuries of all team sports (71.4 %). The lower extremity was the most affected body region overall, followed by the upper extremity. Head injuries were mainly seen in Ice hockey and American football and concussion additionally frequently in team handball. Slight injuries like sprains or contusions occurred most frequently in all team sports. In soccer and team handball, injuries sustained in competition were significantly more severe (p < 0.001) than those sustained in practice.

Volleyball and basketball had a trend to higher rate of severe injuries sustained during practice sessions.

Conclusion Depending on the specific injury profile of each team sports, injury prevention strategies should address competitive as well as training situations, which

may need different strategies.
Graphene-insulator-semiconductor capacitors as superior test structures for photoelectric determination of semiconductor devices band diagrams
Authors: Piskorski K. , Passi V. , Ruhkopf J. , Lemme M. C. , Przewlocki H. M.
Published: May 2018

We report on the advantages of using Graphene-Insulator-Semiconductor (GIS) instead of Metal-Insulator-Semiconductor (MIS) structures in reliable and precise photoelectric determination of the band alignment at the semiconductor-insulator interface and of the insulator band gap determination. Due to the high transparency to light of the graphene gate in GIS structures large photocurrents due to emission of both electrons and holes from the substrate and negligible photocurrents due to emission of carriers from the gate can be obtained, which allows reliable determination of barrier heights for both electrons, Ee and holes, Eh from the semiconductor substrate. Knowing the values of both Ee and Eh allows direct determination of the insulator band gap EG(I). Photoelectric measurements were made of a series of Graphene-SiO2-Si structures and an example is shown of the results obtained in sequential measurements of the same structure giving the following barrier height values: Ee = 4.34 ± 0.01 eV and Eh = 4.70 ± 0.03 eV. Based on this result and results obtained for other structures in the series we conservatively estimate the maximum uncertainty of both barrier heights estimations at ± 0.05 eV. This sets the SiO2 band gap estimation at EG(I) = 7.92 ± 0.1 eV. It is shown that widely different SiO2 band gap values were found by research groups using various determination methods. We hypothesize that these differences are due to different sensitivities of measurement methods used to the existence of the SiO2 valence band tail.
A new method for spatial structure detection of complex inner cavities based on 3D γ-photon imaging
Authors: Xiao Hui , Zhao Min , Liu Jiantang , Liu Jiao , Chen Hao
Published: May 2018

This paper presents a new three-dimensional (3D) imaging method for detecting the spatial structure of a complex inner cavity based on positron annihilation and γ-photon detection. This method first marks carrier solution by a certain radionuclide and injects it into the inner cavity where positrons are generated. Subsequently, γ-photons are released from positron annihilation, and the γ-photon detector ring is used for recording the γ-photons. Finally, the two-dimensional (2D) image slices of the inner cavity are constructed by the ordered-subset expectation maximization scheme and the 2D image slices are merged to the 3D image of the inner cavity. To eliminate the artifact in the reconstructed image due to the scattered γ-photons, a novel angle-traversal model is proposed for γ-photon single-scattering correction, in which the path of the single scattered γ-photon is analyzed from a spatial geometry perspective. Two experiments are conducted to verify the effectiveness of the proposed correction model and the advantage of the proposed testing method in detecting the spatial structure of the inner cavity, including the distribution of gas–liquid multi-phase mixture inside the inner cavity. The above two experiments indicate the potential of the proposed method as a new tool for accurately delineating the inner structures of industrial complex parts.
Observation of conformational changes in ethylene glycol–water complexes by FTIR–ATR spectroscopy and computational studies
Authors: Guo Yu-Cong , Cai Chen , Zhang Yun-Hong
Published: May 2018

Attenuated total reflectance - Fourier transform infrared (ATR-FTIR) spectra of ethylene glycol–water (abbreviated as EG–H2O) mixtures were measured at 298 K with the ethylene glycol molar ratio ranging from 0.01 to 1400. The two bands at 1033 and 1082 cm-1 were assigned to be the C-C stretching vibration modes related to the trans- and gauche- conformation of EG. The absorbance of the two bands was found to be sensitive to the molar ratios. We made theoretical calculation for ten conformations of the EG molecules to understand the conformational transformation of EG molecules changing with EG–H2O molar ratios. The absorbance ratio (A1033/A1082) was used to determine the trans- and gauche- conformation ratio with the calculated (AνO-C-C-O-T/AνO-C-C-O-G) as standard. When the molar ratio of water and EG (xH2O/xEG) is smaller than 0.4, strong associations formed by the intermolecular hydrogen bonds were dominant in the solutions and the proportion of gauche- conformation was about 0.5. Within the region of 0.4< xH2O/xEG < 20, the intermolecular hydrogen bonds structure between EG molecules were broken by the water molecules and the structure of most EG molecules changed from trans- to gauche- conformation. The blue shift of the peaks indicated the increasing hydrogen bonding between water and EG. When xH2O/xEG is larger than 20, the monomers of molecules started to appear in the EG–H2O solution. The gauche- conformation was the dominated conformation in the dilute EG–H2O solution with proportion of 0.87. In the CH2 rocking vibration (δC-H) region, the computational results showed that the majority bands in this region were influenced by the gauche- conformation which can be divided into group G1 or G2. The transformation between the gauche- conformations of EG molecules can be studied by combining the experimental results and the computational results, The proportion of G1 for the EG-rich solution was about 0.71 while it decreased to 0.55 for the H2O–rich solution.
Flexible selection of the solute region in replica exchange with solute tempering: Application to protein-folding simulations
Authors: Kamiya Motoshi , Sugita Yuji
Published: May 2018

Replica-exchange molecular dynamics (REMD) and their variants have been widely used in simulations of the biomolecular structure and dynamics. Replica exchange with solute tempering (REST) is one of the methods where temperature of a pre-defined solute molecule is exchanged between replicas, while solvent temperatures in all the replicas are kept constant. REST greatly reduces the number of replicas compared to the temperature REMD, while replicas at low temperatures are often trapped under their conditions, interfering with the conformational sampling. Here, we introduce a new scheme of REST, referred to as generalized REST (gREST), where the solute region is defined as a part of a molecule or a part of the potential energy terms, such as the dihedral-angle energy term or Lennard-Jones energy term. We applied this new method to folding simulations of a β-hairpin (16 residues) and a Trp-cage (20 residues) in explicit water. The protein dihedral-angle energy term is chosen as the solute region in the simulations. gREST reduces the number of replicas necessary for good random walks in the solute-temperature space and covers a wider conformational space compared to the conventional REST2. Considering the general applicability, gREST should become a promising tool for the simulations of protein folding, conformational dynamics, and an in silico drug design.
A conductive grating sensor for online quantitative monitoring of fatigue crack
Authors: Li Peiyuan , Cheng Li , Yan Xiaojun , Jiao Shengbo , Li Yakun
Published: May 2018

Online quantitative monitoring of crack damage due to fatigue is a critical challenge for structural health monitoring systems assessing structural safety. To achieve online quantitative monitoring of fatigue crack, a novel conductive grating sensor based on the principle of electrical potential difference is proposed. The sensor consists of equidistant grating channels to monitor the fatigue crack length and conductive bars to provide the circuit path. An online crack monitoring system is established to verify the sensor’s capability. The experimental results prove that the sensor is suitable for online quantitative monitoring of fatigue crack. A finite element model for the sensor is also developed to optimize the sensitivity of crack monitoring, which is defined by the rate of sensor resistance change caused by the break of the first grating channel. Analysis of the model shows that the sensor sensitivity can be enhanced by reducing the number of grating channels and increasing their resistance and reducing the resistance of the conductive bar.
Progress on MEVVA source VARIS at GSI
Authors: Adonin A. , Hollinger R.
Published: May 2018

For the last few years, the development of the VARIS (vacuum arc ion source) was concentrated on several aspects. One of them was the production of high current ion beams of heavy metals such as Au, Pb, and Bi. The requested ion charge state for these ion species is 4+. This is quite challenging to produce in vacuum arc driven sources for reasonable beam pulse length (>120 µs) due to the physical properties of these elements. However, the situation can be dramatically improved by using the composite materials or alloys with enhanced physical properties of the cathodes. Another aspect is an increase of the beam brilliance for intense U4+ beams by the optimization of the geometry of the extraction system. A new 7-hole triode extraction system allows an increase of the extraction voltage from 30 kV to 40 kV and also reduces the outer aperture of the extracted ion beam. Thus, a record beam brilliance for the U4+ beam in front of the RFQ (Radio-Frequency Quadrupole) has been achieved, exceeding the RFQ space charge limit for an ion current of 15 mA. Several new projectiles in the middle-heavy region have been successfully developed from VARIS to fulfill the requirements of the future FAIR (Facility for Antiproton and Ion Research) programs. An influence of an auxiliary gas on the production performance of certain ion charge states as well as on operation stability has been investigated. The optimization of the ion source parameters for a maximum production efficiency and highest particle current in front of the RFQ has been performed. The next important aspect of the development will be the increase of the operation repetition rate of VARIS for all elements especially for uranium to 2.7 Hz in order to provide the maximum availability of high current ion beams for future FAIR experiments.
Bias-induced conformational switching of supramolecular networks of trimesic acid at the solid-liquid interface
Authors: Ubink J. , Enache M. , Stöhr M.
Published: May 2018

Using the tip of a scanning tunneling microscope, an electric field-induced reversible phase transition between two planar porous structures (“chickenwire” and “flower”) of trimesic acid was accomplished at the nonanoic acid/highly oriented pyrolytic graphite interface. The chickenwire structure was exclusively observed for negative sample bias, while for positive sample bias only the more densely packed flower structure was found. We suggest that the slightly negatively charged carboxyl groups of the trimesic acid molecule are the determining factor for this observation: their adsorption behavior varies with the sample bias and is thus responsible for the switching behavior.
Forward-flux sampling with jumpy order parameters
Authors: Haji-Akbari Amir
Published: May 2018

Forward-flux sampling (FFS) is a path sampling technique that has gained increased popularity in recent years and has been used to compute rates of rare event phenomena such as crystallization, condensation, hydrophobic evaporation, DNA hybridization, and protein folding. The popularity of FFS is not only due to its ease of implementation but also because it is not very sensitive to the particular choice of an order parameter. The order parameter utilized in conventional FFS, however, still needs to satisfy a stringent smoothness criterion in order to assure sequential crossing of FFS milestones. This condition is usually violated for order parameters utilized for describing aggregation phenomena such as crystallization. Here, we present a generalized FFS algorithm for which this smoothness criterion is no longer necessary and apply it to compute homogeneous crystal nucleation rates in several systems. Our numerical tests reveal that conventional FFS can sometimes underestimate the nucleation rate by several orders of magnitude.
Dispersion properties of plasma cladded annular optical fiber
Authors: KianiMajd M. , Hasanbeigi A. , Mehdian H. , Hajisharifi K.
Published: May 2018

One of the considerable problems in a conventional image transferring fiber optic system is the two-fold coupling of propagating hybrid modes. In this paper, using a simple and practical analytical approach based on exact modal vectorial analysis together with Maxwell's equations, we show that applying plasma as a cladding medium of an annular optical fiber can remove this defect of conventional fiber optic automatically without any external instrument as the polarization beam splitter. Moreover, the analysis indicates that the presence of plasma in the proposed optical fiber could extend the possibilities for controlling the propagation property. The proposed structure presents itself as a promising route to advanced optical processing and opens new avenues in applied optics and photonics.
Calcium doped MAPbI3 with better energy state alignment in perovskite solar cells
Authors: Lu Chaojie , Zhang Jing , Hou Dagang , Gan Xinlei , Sun Hongrui , Zeng Zhaobing , Chen Renjie , Tian Hui , Xiong Qi , Zhang Ying , Li Yuanyuan , Zhu Yuejin
Published: May 2018

The organic-inorganic perovskite material with better energy alignment in the solar cell device will have a profound impact on the solar cell performance. It is valuable to tune the energy states by element substitution and doping in perovskites. Here, we present that Ca2+ is incorporated into CH3NH3PbI3, which up-shifts the valence band maximum and the conduction band minimum, leading to a difference between the bandgap and the Fermi level in the device. Consequently, Ca2+ incorporation results in an enhancement of the photovoltage and photocurrent, achieving a summit efficiency of 18.3% under standard 1 sun (AM 1.5). This work reveals the doped perovskite to improve the solar cell performance by tuning the energy state.
Electric transport and the pseudogap in the 1-2-3 HTSC system, under all-around compression (Review Article)
Authors: Vovk R. V. , Solovjov A. L.
Published: May 2018

The problem of how high pressure impacts various electric transport mechanisms in HTSC compounds REBa2Cu3O7-δ (RE = Y, or another rare-earth ion) is considered. The features of the crystal structure and the effects that structural defects of different morphologies have on the electrical conductivity of these compounds in the normal, pseudogap, and superconducting states, are discussed. A review of the experimental data obtained in studies on the effect of high hydrostatic pressure on the various electric transport mechanisms of REBa2Cu3O7-δ compounds, with varying composition and technical prehistory, is conducted. Different theoretical models devoted to the subject of how high pressure impacts the electrical conductivity of 1-2-3 HTSC system compounds are discussed.
Hierarchy of low-energy models of the electronic structure of cuprate HTSCs: The role of long-range spin-correlated hops
Authors: Val'kov V. V. , Mitskan V. A. , Dzebisashvili D. M. , Barabanov A. F.
Published: May 2018

It is shown that for the three-band Emery p–d-model that reflects the real structure of the CuO2-plane of high-temperature superconductors in the regime of strong electron correlations, it is possible to carry out a sequence of reductions to the effective models reproducing low-energy features of elementary excitation spectrum and revealing the spin-polaron nature of the Fermi quasiparticles. The first reduction leads to the spin-fermion model in which the subsystem of spin moments, coupled by the exchange interaction and localized on copper ions, strongly interacts with oxygen holes. The second reduction deals with the transformation from the spin-fermion model to the φ–d-exchange model. An important feature of this transformation is the large energy of the φ–d-exchange coupling, which leads to the formation of spin polarons. The use of this fact allows us to carry out the third reduction, resulting in the t̃−J̃*−I-model. Its distinctive feature is the importance of spin-correlated hops as compared to the role of such processes in the commonly used t–J*-model derived from the Hubbard model. Based on the comparative analysis of the spectrum of Fermi excitations calculated for the obtained effective models of the CuO2-plane of high-temperature superconductors, the important role of the usually ignored long-range spin-correlated hops is determined.
Anomalous interfacial tension temperature dependence of condensed phase drops in magnetic fluids
Authors: Ivanov Aleksey S.
Published: May 2018

Interfacial tension temperature dependence σ(T) of the condensed phase (drop-like aggregates) in magnetic fluids undergoing field induced phase transition of the “gas-liquid” type was studied experimentally. Numerical analysis of the experimental data has revealed the anomalous (if compared to ordinary one-component fluids) behavior of the σ(T) function for all tested magnetic colloid samples: the condensed phase drops at high T ≈ 75 C exhibit higher σ(T) than the drops condensed at low T ≈ 20 C. The σ(T) behavior is explained by the polydispersity of magnetic colloids: at high T, only the largest colloidal particles are able to take part in the field induced condensation; thus, the increase of T causes the growth of the average particle diameters inside the drop-like aggregates, what in its turn results in the growth of σ(T). The result is confirmed by qualitative theoretical estimations and qualitative experimental observation of the condensed phase “evaporation” process after the applied magnetic field is removed: the drops that are formed due to capillary instability of the drop-like aggregates retract by one order of magnitude faster at high T, and the evaporation of the drops slows down at high T.
Stable and selective self-assembly of α-lipoic acid on Ge(001) for biomolecule immobilization
Authors: Kazmierczak M. , Flesch J. , Mitzloff J. , Capellini G. , Klesse W. M. , Skibitzki O. , You C. , Bettenhausen M. , Witzigmann B. , Piehler J. , Schroeder T. , Guha S.
Published: May 2018

We demonstrate a novel method for the stable and selective surface functionalization of germanium (Ge) embedded in silicon dioxide. The Ge(001) surface is functionalized using α-lipoic acid (ALA), which can potentially be utilized for the immobilization of a wide range of biomolecules. We present a detailed pH-dependence study to establish the effect of the incubation pH value on the adsorption layer of the ALA molecules. A threshold pH value for functionalization is identified, dividing the examined pH range into two regions. Below a pH value of 7, the formation of a disordered ALA multilayer is observed, whereas a stable well-ordered ALA mono- to bi-layer on Ge(001) is achieved at higher pH values. Furthermore, we analyze the stability of the ALA layer under ambient conditions, revealing the most stable functionalized Ge(001) surface to effectively resist oxidation for up to one week. Our established functionalization method paves the way towards the successful immobilization of biomolecules in future Ge-based biosensors.
Valence and charge-transfer optical properties for some SinCm(m,n ≤ 12) clusters: Comparing TD-DFT, complete-basis-limit EOMCC, and benchmarks from spectroscopy
Authors: Lutz Jesse J. , Duan Xiaofeng F. , Ranasinghe Duminda S. , Jin Yifan , Margraf Johannes T. , Perera Ajith , Burggraf Larry W. , Bartlett Rodney J.
Published: May 2018

Accurate optical characterization of the closo-Si12C12 molecule is important to guide experimental efforts toward the synthesis of nano-wires, cyclic nano-arrays, and related array structures, which are anticipated to be robust and efficient exciton materials for opto-electronic devices. Working toward calibrated methods for the description of closo-Si12C12 oligomers, various electronic structure approaches are evaluated for their ability to reproduce measured optical transitions of the SiC2, Si2Cn (n = 1–3), and Si3Cn (n = 1, 2) clusters reported earlier by Steglich and Maier [Astrophys. J. 801, 119 (2015)]. Complete-basis-limit equation-of-motion coupled-cluster (EOMCC) results are presented and a comparison is made between perturbative and renormalized non-iterative triples corrections. The effect of adding a renormalized correction for quadruples is also tested. Benchmark test sets derived from both measurement and high-level EOMCC calculations are then used to evaluate the performance of a variety of density functionals within the time-dependent density functional theory (TD-DFT) framework. The best-performing functionals are subsequently applied to predict valence TD-DFT excitation energies for the lowest-energy isomers of SinC and Sin−1C7−n (n = 4–6). TD-DFT approaches are then applied to the SinCn (n = 4–12) clusters and unique spectroscopic signatures of closo-Si12C12 are discussed. Finally, various long-range corrected density functionals, including those from the CAM-QTP family, are applied to a charge-transfer excitation in a cyclic (Si4C4)4 oligomer. Approaches for gauging the extent of charge-transfer character are also tested and EOMCC results are used to benchmark functionals and make recommendations.
Energy and charge transfer effects in two-dimensional van der Waals hybrid nanostructures on periodic gold nanopost array
Authors: Kim Jun Young , Kim Sun Gyu , Youn Jong Won , Lee Yongjun , Kim Jeongyong , Joo Jinsoo
Published: May 2018

Two-dimensional (2D) semiconducting MoS2 and WSe2 flakes grown by chemical vapor deposition were mechanically hybridized. A hexagonal boron nitride (h-BN) dielectric flake was inserted between MoS2 and WSe2 flakes to investigate the nanoscale optical properties of 2D van der Waals hybrid nanostructures. The fabricated MoS2/WSe2 and MoS2/h-BN/WSe2 van der Waals hybrid nanostructures were loaded on a periodic gold nanopost (Au-NPo) array to study energy and charge transfer effects at the surface plasmon resonance (SPR) condition. Nanoscale photoluminescence (PL) spectra of the 2D hybrid nanostructures were measured using a high-resolution laser confocal microscope (LCM). A shift of the LCM PL peak of the MoS2/WSe2 n-p hybrid nanostructures was observed owing to the charge transfer. In contrast, the shift of the LCM PL peak of the MoS2/h-BN/WSe2 n-insulator-p hybrid nanostructure was not considerable, as the inserted h-BN dielectric layer prevented the charge transfer. The intensity of the LCM PL peak of the MoS2/h-BN/WSe2 hybrid nanostructure considerably increased once the nanostructure was loaded on the Au-NPo array, owing to the energy transfer between the 2D materials and the Au-NPo array at the SPR condition, which was confirmed by the increase in the LCM Raman intensity.