bluuebunny/crossref_metadata_2025 huggingface dataset:
Awareness that coal-powered energy is environmentally degrading insignificantly affects its consumption
Authors: Ragusa Angela T.
Published: March 2020

This paper contributes findings from a social survey conducted to examine individual awareness of coal’s non-renewability, environmental issues, and home energy behaviours. The sample exhibited high (86%) awareness of coal’s non-renewability and 74% self-identified energy issues as key environmental problems affecting their lives. Government presumptions that education campaigns are needed to increase Australian public awareness of carbon emissions and may induce pro-environmental energy behaviours are questioned. Energy issue awareness failed to significantly affect 4 home energy behaviours (choosing A/C settings, type of home temperature control, turning lights off in unoccupied rooms, turning appliances off standby) for ‘environmental sustainability’ reasons. Findings support international research documenting disparity between individual awareness of environmental issues and pro-environmental actions for such issues. Consistent with prior research, age was the most significant factor affecting pro-environmental energy behaviours. Older individuals were most likely to consider environmental sustainability for home temperature and A/C settings. Education, age, and energy issue awareness did not significantly affect ‘low stakes’ consumption behaviours (appliances or lights) for environmental reasons. In locations with non-renewable energy, policy and education initiatives improving knowledge that aggregated carbon consumption from seemingly minor individual behaviours may reduce environmental degradation may make ‘unnecessary’ energy consumption less culturally normative or acceptable.
Contribution to the Environmental sustainability by improving the walking behaviour through neighbourhoods’ design with special reference to developing countries
Authors: Gul Yasmeen , Sultan Zahid , Jokhio Gul Ahmed
Published: March 2020

The neighbourhood design (ND) factors such as land-use mix (LUM), street connectivity and housing density have the potential to enhance the walking. A limited number of studies have investigated the association of ND factors with walking in developing countries. Therefore, the objective of this study is to compare the ND factors and investigate their association with walking. The LUM, street connectivity and housing density were measured objectively while walking was calculated subjectively (n-1,042adults). Independent sample t-test and Binary logistic analysis has been used to investigate the comparison and association between ND factors and walking. The results show that two out of three ND indicators are significantly different in both types of neighbourhoods and have positive association with walking Therefore, it can be concluded that, for the sake of walking in developing countries, the neighbourhoods should have mix of different land-uses and well-connected streets rather than sealing the neighbourhoods with walls.
Cruising for better air quality: Australian clean air submissions, issues, and recommendations
Authors: Ragusa Angela T. , Crampton Andrea
Published: March 2020

Clean air remains an elusive and inequitable human right. Air pollution unnecessarily increases morbidity, mortality rates, and environmental degradation globally. This paper presents results from a content analysis of all (n = 133) submissions to the 2019 New South Wales Government call for public feedback to its ‘Clean Air’ issues and action priorities. Findings show stakeholder agreement that air pollution’s regulation and measurement are problematic. Issue framing divulged stakeholder agendas, particularly for shipping industries, highlighted inconsistencies in government and industry regulations, and revealed mistrust and issue partiality. Science literacy, proximity to pollution source, socioeconomic status, and pollution visibility affected issue descriptions and recommendations. Cruise ships in Sydney Harbour received disproportionately high focus relative to their contribution to the shipping industry’s contribution to local air pollution. Government and health body submissions proposed public education, awareness raising, and personal action as key steps to avoid emission exposure. We argue such ‘deficit theory’ approaches are inadequate in light of international research evidencing pollution visibility and personal perception poorly reflect scientific air quality measures. To surpass Australian NIMBY approaches to air pollution, we propose adopting European international legislative reform to equitably enforce clean air ‘rights’ and actions across industries, governments, and communities, irrespective of stakeholder priorities.
Case study of industrial green development on the perspective of ecological civilization in China
Authors: Liu Dan , Liu Li
Published: March 2020

With the increasing concern of ecological crisis and sustainable development, the issue of green development has aroused widespread focus in the academic and practical domain. Green development and ecological civilization are especially important to developing country, which interact and both are the basis of sustainable development. This paper analyzed the present background, status, importance and problem about green development in China and shared a case study of the practice in Green Development in Anshan, as well as proposed specific tactics to promote realization of goal of green development and ecological civilization on the two main direction from the perspective of ecological civilization, which enriches the theory of green development and ecological civilization and guides the practical implication and implement of industry transformation.
Decarbonizing warehousing activities through digitalization and automatization with WMS integration for sustainability supporting operations
Authors: Minashkina Daria , Happonen Ari
Published: March 2020

The current strong outsourcing trend dictates that the efficiency of outsourced warehousing is a big contributing impact factor for the carbon footprint from supply chains. A good warehouse management system boosts warehousing eco-friendliest by reducing space waste and unnecessary number of material movements, to ensure continuous fast materials flow and to keep the heating and cooling costs to a minimum. All this may happen on some lengths inside the traditional manual warehousing scenes, but in fact, if the highest level of efficiency is wanted/needed, the operator shall need to automate, digitalize and robotize their operations. Authors presents an example of automation in the warehousing context, where the warehouse operator is capable of turning around an order line as an outgoing packet, even in high peak load times under 3h time period. This sort of efficiency means less needed storage space as items stay less time in the warehouse and such automatization also gives the 3PLs possibility to store materials in high rising automated systems like automated storage and retrieval systems to optimize their space usage. All combined, the future warehouse operations can make a positive impact on efforts to reduce overall CO₂emissions made by supply chains.
Emission reduction strategy between Chinese and foreign metropolitan areas
Authors: Wang Jun
Published: March 2020

Because of the important position of metropolitan areas in the national economy, this paper puts forward the important responsibility of metropolitan areas in a country’s emission reduction task. Taking Chicago Metropolitan Area, Manchester Metropolitan Area and Tokyo Metropolitan Area as the research objects, this paper discusses the action of reducing emissions in international metropolitan area from three aspects: formulation of emission reduction targets, specific emission reduction strategies and regional coordination mechanism. Then, by comparing the emission reduction actions of the Yangtze River Delta, the Pearl River Delta and the Beijing-Tianjin-Hebei metropolitan areas in China, this paper analyses the Enlightenment of the emission reduction of the international metropolitan areas to China, and puts forward the areas that need to be further strengthened in the emission reduction of the metropolitan areas in China.
Environmental benefits of incorporating palm oil fuel ash in cement concrete and cement mortar
Authors: Jokhio G.A. , Hamada H.M. , Humada A.M. , Gul Y , Abu-Tair Abid
Published: March 2020

Palm oil fuel ash (POFA) is a by-product waste material from palm oil with many economic and environmental benefits. A lack of enough information on the advantages of POFA in the concrete production in various proportions was the main cause to carry out this work. This paper shows advantages of POFA as a partial replacement of cement in concrete production, especially cement mortar. The data collection has been done from the literature review related to the use of POFA as partial cement replacement in the production of cement concrete and mortar. Therefore, this paper can potentially become a guide for researchers and manufacturers to use POFA in various proportions to replace the ordinary Portland cement (OPC) in cement concrete and mortar. The positive and negative impact resulting from this material has been discussed carefully. This study recommends that researchers and academics should perform more experimental works in order to illustrate the desired benefits from POFA as cement replacement, thus mitigate the adverse environmental impacts of cement.
Technologies for reducing emissions and costs in combined heat and power production
Authors: Auvinen Harri , Santti Ulla , Happonen Ari
Published: March 2020

According Finnish Energy association, in Finland roughly three-quarters of district heat production is based on combined heat and power (CHP) generation. Correspondingly, one-third of electricity is generated using CHP. In Finland, the market share of CHP derived electricity is significant, and therefore used technologies and fuels should be carefully chosen in terms of costs and emissions. In this paper we consider a case of Kuopio, which is the 9thbiggest city in Finland. In the past few years, the total usage of fossil fuels has been decreasing and the use of renewable fuels has correspondingly been increasing. The amount of electricity produced with peat has gradually decreased during the last 15 years. The common explaining factor for these trends is the political will and national and municipal level shared common aim to reduce greenhouse gases and emissions. Furthermore, there are new technical innovations available, such as flue gas scrubber and district cooling system, which has been proven to be significant tools to reduce emission and at the same time investments into these innovations have been shown to save energy and money, meaning being greener has been also financially lucrative decision for these sustainability enhancing technology investors.
Simulataneous removal of nitrogen and sulfur oxides using the NaClO2/NaOH composite absorbent via ultrasonic atomization
Authors: Lin Shuang , Liu Wei , Xu Dongyao
Published: March 2020

In this study, NaClO2 was used as an oxidant and mixed with NaOH to prepare a sodium-based composite absorbent. Simultaneous desulfurization and denitrification experiments were conducted in an ultrasonic atomization reactor and the effects of experimental parameters including pH value, NaClO2 concentration, initial concentration of NO, reaction temperature, the addition of SO2 and the utilization of ultrasonic atomization on desulfurization and denitrification efficiencies were investigated. Under the circumstance of the pH of 10, oxygen content of 8%, reaction temperature of 55oC, and NO concentration of 500 mg/m3, SO2 concentration of 1400 mg/m3, 69.38% of NO and 99.95% of SO2 can be removed using the composite absorbent composed of 0.02 mol/L NaClO2 and 0.1mmol/L NaOH. Ultrasonic atomization increased the denitrification rate by 10.6%.
Assessing the effectiveness of Hyparrhenia hirta in the rehabilitation of the ecosystem of a gold mine dump
Authors: Okereafor G.U , Makhatha M.E , Mekuto L , Mavumengwana V
Published: March 2020

The mining of gold is associated with several environmental challenges such as acid mine drainage, release of toxic metals which are associated to tailing sediments and have adversely impacted human health and the ecosystem. With increasing global population that is faced with limited land resources for agricultural activities, there is need for land restoration through effective rehabilitation of contaminated soils. The introduction of Hyparrhenia hirta, an indigenous grass specie as a phytoremediation technique for in situ rehabilitation of degraded soil is not only an economically viable approach but also environmentally friendly. Hyparrhenia hirta being a tufted and wiry perennial grass that is invasive with deep root system often aid in stabilizing the ecosystem owing to their self-fertile and drought resistant potentials that support that prevalence in harsh conditions at mine dump sites. In this study, mine tailings at Gold One Mine, Ekuhurleni, South Africa were assessed for heavy metal contents at the same time analysing the uptake of such heavy metals by Hyparrhenia hirta grass specie. The total metal mean concentrations was high (4023.67 mg/kg) for Hyparrhenia hirta which absorbed more of the following mean metal concentrations: 46.10 mg/kg for Cu; 40.08 mg/kg for Zn; 859.12 mg/kg for Pb; 618.26 mg/kg for Cr; 151.70 mg/kg for Co and 2308.41 mg/kg for Ni. The tailings were strongly acidic with a pH range of 3.86 – 4.34. These heavy metals despite the acidic environments were successfully absorbed by Hyparrhenia hirta grass specie. Along these lines Hyparrhenia hirta was discovered reasonable for re-vegetation of mine tailings dump as it has the capacity to hold together tailings sediments against wind and water erosion.
Assessment of heavy metals in RDF for thermochemical conversion
Authors: Adefeso Ismail Babatunde , Ikhu-Omoregbe Daniel , Isa Yusuf M.
Published: March 2020

Thermal treatment applications towards production of energy from raw and pre-treated municipal solid waste (MSW) are continuously growing context in contemporary waste-to-energy technology. The quality of MSW needs an improved analysis to enhance her choice of energy exploitation and environmental assessment of fly and bottom ashes associated with thermochemical conversions. The MSW were collected from municipal solid waste disposal facilities (MSWDF) in Cape Town to investigate heavy metals distributions in MSW. The MSW were pre-treated to improve the quality of MSW. The 7700 Series quadrupole ICP-MS solution method was used to determine concentrations and distributions of some heavy metals from MSWDF in Cape Town. This study further predicted distributions of heavy metals in fly and bottom ashes by a model. The results showed that accumulation of high concentrations of heavy metals in bottom ash residue could be a good remedy for heavy metals control. The heavy metals (especially Pb, Zn and Hg) emissions could be technically monitored and controlled from escaping to urban air-sheds atmosphere and prevent from their consequential secondary environmental and health implication.
The viscous behavior and potassium removal capacity of CaO–SiO2–8wt%MgO–17wt%Al2O3–2.5wt%BaO–K2O slag
Authors: Liu Wenguo , Xing Xiangdong , Zuo Haibin
Published: March 2020

The viscous behavior and potassium removal capacity of CaO–SiO2–8wt%MgO–17wt%Al2O3–2.5wt%BaO–K2O slag system with CaO/SiO2 of 1.07 were studied. The effect of K2O content ranging from 0 to 5 wt% on the viscosity, slag structure, apparent activation energy and potassium removal rate of present slag were analyzed. The results showed that with increase of K2O content in slag, the viscosity and apparent activation energy tended to increase. When adding K2O into the present slag, K+ ion rather than Ba2+ could preferentially compensate [AlO4] tetrahedron and more complex network structures would be formed, leading to higher polymerization degree of slag. The potassium removal rate was related to the reduction degree of K+ by carbon, and with rising of temperature and increasing of K2O content there was a decreasing trend for the potassium removal capacity of slag.
Prevalence, risk factors and global impact of musculoskeletal injuries among endoscopists: a nationwide European study
Authors: Morais Rui , Vilas-Boas Filipe , Pereira Pedro , Lopes Pedro , Simões Carolina , Dantas Eduardo , Cunha Inês , Roseira Joana , Cortez-Pinto João , Silva João , Lage Jorge , Caine Mafalda , Rocha Manuel , Flor de Lima Margarida , Costa Santos Maria Pia , Garrido Mónica , Sousa Paula , Marcos Pedro , Azevedo Richard , Castro Rui , Cúrdia Gonçalves Tiago , Leal Tiago , Magno-Pereira Vítor , Ramalho Rosa , Rodrigues-Pinto Eduardo , Macedo Guilherme
Published: March 2020

Background and study aims Previous studies have suggested a high prevalence of musculoskeletal injuries (MI) in endoscopists. Little evidence has come from European countries. Our main aim was to evaluate the prevalence, type, and impact of MI among Portuguese endoscopists. We also sought to identify risk factors for the development, severity and number of endoscopy-related MI.

Material and methods A 48-question electronic survey was developed by a multidisciplinary group. The electronic survey was sent to all members of Portuguese Society of Gastroenterology (n = 705) during May 2019. Study data were collected and managed using REDCap electronic data capture tools hosted at SPG – CEREGA.

Results The survey was completed by 171 endoscopists (response rate of 24.3 %), 55.0 % female with a median age of 36 years (range 26–78). The prevalence of at least one MI related to endoscopy was 69.6 % (n = 119), the most frequent being neck pain (30.4 %) and thumb pain (29.2 %). The median time for MI development was 6 years (range 2 months-30 years). Severe pain was reported by 19.3 %. Change in endoscopic technique was undertaken by 61.3 % and reduction in endoscopic caseload was undertaken by 22.7 %. Missing work was reported by 10.1 %, with the median time off from work being 30 days (range 1–90). Female gender and ≥ 15 years in practice were independently associated with MI and severe pain. Years in practice, weekly-time performing endoscopy, and gender were significant predictors of the number of MI.

Conclusions Prevalence of MI was significant among Portuguese endoscopists and had a relevant impact on regular and professional activities.
Current challenges and future needs of clinical and endoscopic training in gastroenterology: a European survey
Authors: Maida Marcello , Alrubaiy Laith , Bokun Tomislav , Bruns Tony , Castro Valeria , China Louise , Conroy Guillaume , Trabulo Daniel , Van Steenkiste Christophe , Voermans Rogier P. , Burisch Johan , Ianiro Gianluca
Published: March 2020

Background and study aims A universal European training program in gastroenterology and hepatology is currently not available. The European Board of Gastroenterology and Hepatology (EBGH) has produced guidance regarding expected competencies for European gastroenterology trainees but it is unclear whether these have been incorporated in national curricula. The aim of this study was to provide an in-depth assessment of training and research opportunities, professional activities and of socioeconomic aspects of gastroenterology training across Europe through a web-based 90-point questionnaire.

Materials and methods Physicians in their last year or who had recently finished their training, from 16 European countries, were invited to answer the questionnaire.

Results A total of 144 physicians answered the survey. A minimum number of procedures is required before completing training in nine of 16 countries (56 %). Overall, European trainees dedicate a median of 12 months (IQR 6–25) of their training period to endoscopy and a median of 3 months (IQR 0–6) to ultrasound. Training in interventional endoscopy was not always exhaustive, as about 50 % of participants performed fewer of several interventional procedures than was recommended by EBGH, most participants did not perform endoscopic hemostasis or endoscopic mucosal resection, and nearly a half of participants had no access to pancreatobiliary endoscopy training. Finally, up to 13 % of residents complete their training without the supervision of a mentor.

Conclusion In this large European survey, deep gaps and considerable differences in several gastroenterology training activities were found both among and within 16 European countries. Homogenization of educational programs and training opportunities across Europe is therefore necessary.
Erythrodermie und hypernatriämische Dehydratation beim
Neugeborenen – eine Fallbeschreibung des
Netherton-Syndroms
Authors: Anneser Verena , Mueller Fabian , Wild Florian , Metze Dieter , Schneider Holm , Steinhoff Martin , Seeliger Stephan
Published: March 2020

Hintergrund Das Netherton-Syndrom (NS) ist eine seltene, schwer
verlaufende, autosomal rezessive Form einer kongenitalen Ichthyose,
verbunden mit einem charakteristischen Defekt des Haarschaftes
(Trichorrhexis invaginata), Erythrodermie und einer ausgeprägten
Atopieneigung auf dem Boden eines veränderten Immunsystems mit
erhöhten IgE-Werten. Seine Inzidenz wird mit 1:100 000 bis
1:200 000 angegeben. Die Ursache sind Mutationen im Gen SPINK5
(5q31-q32), das für den Serinprotease-Inhibitor LEKTI kodiert.
Betroffene Neugeborene zeigen ein nicht einheitliches Bild einer
generalisierten Erythrodermie mit Schuppung der Haut bis zum Vollbild eines
Kollodiumbabys. Eine schwerwiegende Komplikation im Neugeborenenalter ist
die hypernatriämische Dehydratation auf dem Boden der unzureichenden
Barrierefunktion der Haut. Im Verlauf stehen rezidivierende Infekte,
Atopieneigung, Diarrhoen und intestinale Malabsorption (Enteropathie) mit
einer damit verbundenen Gedeihstörung im Vordergrund.

Patient/Methode Wir berichten über ein Neugeborenes
mit NS, welches post partum neben einer ausgeprägten Erythrodermie
durch eine schwer zu therapierende hypernatriämische Dehydratation
auffiel.

Ergebnis Die Untersuchung einer Hautprobe unserer Patientin zeigte
eine für das NS typische und richtungsweisende psoariasiforme
Dermatitis mit Fehlen des LEKTI-Proteins. Die schweren rezidivierenden und
behandlungsbedürftigen Elektrolytentgleisungen standen in der
Neonatalperiode als lebensbedrohliche Komplikation im Vordergrund.

Schlussfolgerung Bei Neugeborenen mit Erythrodermie muss an das
seltene Krankheitsbild eines NS gedacht werden, da die betroffenen Kinder
durch Elektrolytentgleisungen sehr gefährdet sind und diese mit
einer hohen Letalität einhergehen. Diagnose und Therapie des NS
erfordern eine sehr gute interdisziplinäre Zusammenarbeit zwischen
Neonatologen, Intensivmedizinern, Dermatologen sowie im Verlauf
Infektiologen und Allergologen. Eine engmaschige Weiterbetreuung bis in das
Jugendalter ist unabdingbar.
Confocal laser endomicroscopy detects colonic inflammation in patients with irritable bowel syndrome: a prospective study
Authors: Robles-Medranda Carlos , Oleas Roberto , Valero Manuel , Puga-Tejada Miguel , Soria-Alcívar Miguel , Ospina Jesenia , Alvarado-Escobar Haydee , Muñoz-Jurado Guillermo , Baquerizo-Burgos Jorge , Pitanga-Lukashok Hannah
Published: March 2020

Background and aims Irritable bowel syndrome (IBS) is considered to be a functional disease, but recent data indicate measurable organic alterations. We aimed to determine the presence of colorectal mucosa microinflammation in vivo via probe-confocal laser endomicroscopy (pCLE) and histological evaluation in IBS patients.

Methods This was a prospective, controlled, nonrandomized single-blind diagnostic trial performed in a tertiary institution. pCLE images and targeted biopsy of each colon segment obtained during colonoscopies of IBS patients and controls were analyzed for inflammatory changes. Biopsies were classified using the Geboes scale, and the odds ratio and overall diagnostic accuracy were calculated.

Results During the 15-month study period, 37 patients were allocated to each group. The mean age was 53.1 ± 14.3 years; 64.9 % were female. Signs of colonic mucosa inflammation were evident on 65.8 % of pCLE images from IBS patients compared to 23.4 % of images from controls (OR 6.28; 4.14–9.52; P < 0.001). In total, 20/37 patients had microinflammation via pCLE in ≥ 3 colon segments in the IBS group, compared to 1/37 in the control group. A Geboes score > 0 was attributed to 60.8 % of biopsies from patients in the IBS group compared to 27.5 % of biopsies from the control group. The sensitivity, specificity, positive and negative predictive values, observed and interrater agreement of pCLE-detected inflammatory changes in IBS using histology as gold standard were 76 %, 91 %, 76 %, 91 %, 86.5 %, and 66.8 %, respectively.

Conclusions Patients with IBS have a six-fold higher prevalence of colorectal mucosa microinflammation than healthy controls. pCLE might be a reliable method to detect colorectal mucosa microinflammation in IBS patients.
Outcomes of endoscopic sleeve gastroplasty; how does it compare to laparoscopic sleeve gastrectomy? A systematic review and meta-analysis
Authors: Mohan Babu P. , Asokkumar Ravishankar , Khan Shahab R. , Kotagiri Rajesh , Sridharan Gurusravanan Kutti , Chandan Saurabh , Ravikumar Naveen PG. , Ponnada Suresh , Jayaraj Mahendran , Adler Douglas G.
Published: March 2020

Background and study aims Endoscopic sleeve gastroplasty (ESG) is a novel moderately invasive technique in endo-bariatrics as compared to laparoscopic sleeve gastrectomy (LSG). Data is limited as to its efficacy and safety.

Methods We searched multiple databases from inception through August 2019 to identify studies that reported on ESG in the treatment of obesity. Our goals were to calculate the pooled rates of total weight loss (%TWL), excess weight loss (%EWL), and body mass index (BMI) at 1 month, 6 months, and 12 months with ESG. We included studies that reported on LSG, in a similar time frame as ESG, and compared the 12-month outcomes.

Results From eight studies on ESG (1815 patients), the pooled rates of %TWL at 1 month, 6 months, and 12 months were 8.7 (7.2–10.2), 15.3 (14.1–16.6) and 17.1 (15.1–19.1), respectively. The pooled rates of %EWL at 1 month, 6 months, and 12 months were 31.7 (29.3–34.1), 59.4 (57–61.8) and 63 (51.3–74.6), respectively. The pooled rates of BMI at 1 m, 6 m, and 12 m were 32.6 (31–34.3), 30.4 (29–31.8) and 30 (27.7–32.3, I2 = 97), respectively. At 12 months, the pooled %TWL, %EWL and BMI with LSG (7 studies, 2179 patients) were 30.5 (27.4–33.5), 69.3 (60.1–78.4) and 29.3 (27.1–31.4) respectively. On comparison analysis, %TWL with LSG was superior to ESG (P = 0.001). %EWL and BMI were comparable. All adverse events, bleeding and gastro-esophageal reflux disease were significantly lower with ESG when compared to LSG.

Conclusion ESG demonstrates acceptable weight loss parameters and seems to have a better safety profile when compared to LSG.
The Use of α-Diazo-γ-butyrolactams in the Büchner–Curtius–Schlotterbeck Reaction of Cyclic Ketones Opens New Entry to Spirocyclic Pyrrolidones
Authors: Krasavin Mikhail , Eremeyeva Maria , Zhukovsky Daniil , Dar’in Dmitry
Published: March 2020

The only cyclic α-diazocarbonyl compound employed in the Büchner–Curtius–Schlotterbeck ring expansion of cyclic ketones to date was α-diazo-γ-butyrolactone. Encouraged by the recent success using α-diazo acetamides in related Tiffeneau–Demjanov type ring expansions, we extended this approach to various α-diazo-γ-butyrolactams, which produced, under BF3·OEt2-promoted conditions, spirocyclic seven-membered ketones. These findings substantially enhance the possibilities offered by cyclic α-diazocarbonyl compounds in constructing privileged spirocyclic scaffolds for drug design.
Acoustic waves in granular packings at low confinement pressure
Authors: Tell Karsten , Dreißigacker Christoph , Tchapnda Alberto Chiengue , Yu Peidong , Sperl Matthias
Published: March 2020

Elastic properties of a granular packing show a nonlinear behavior determined by its discrete structure and nonlinear inter-grain force laws. Acoustic waves show a transition from constant, pressure-dependent sound speed to a shock-wave-like behavior with an amplitude-determined propagation speed. This becomes increasingly visible at low static confinement pressure as the transient regime shifts to lower wave amplitudes for lower static pressure. In microgravity, confinement pressure can be orders of magnitude lower than in a ground-based experiment. In addition, the absence of hydrostatic gradients allows for much more homogeneous and isotropic pressure distribution. We present a novel apparatus for acoustic wave transmission measurements at such low packing pressures. A pressure control loop is implemented by using a microcontroller that monitors static force sensor readings and adjusts the position of a movable wall with a linear-motor until the desired pressure is reached. Measurements of acoustic waves are possible using accelerometers embedded in the granular packing as well as piezos. For excitation, we use a voice-coil-driven wall, with a large variety of signal shapes, frequencies, and amplitudes. This enables experiments in both the linear and strongly nonlinear regimes.
A multi-wavelength streaked optical pyrometer for dynamic shock compression measurements above 2500 K
Authors: Opachich Y. P. , Crum R. S. , Daene M. W. , Dutra E. C. , Mehta H. N. , Shelton H. L. , Watts P. , Akin M. C.
Published: March 2020

This article presents a concept and implementation of a calibrated streaked spectral pyrometer (SSP) temperature diagnostic used in dynamically driven shock experiments on a two-stage gas gun. This system relies upon measuring the total system response using a tunable monochromator, a NIST-traceable calibrated power meter, and a SSP. The diagnostic performance is validated against previously measured temperatures of shock driven z-cut quartz at 99 GPa and 93 GPa. The results are found to agree with the literature to within 5% and are discussed in this manuscript. The experimental setup utilizes measurements from multiple SSP systems per sample, providing several independent measurements and substantially increasing confidence in the extrapolated shock driven sample temperature.
Hysteresis and current reduction during E–H mode transition in an inductively coupled plasma
Authors: Moon Jun-Hyeon , Kim Kyung-Hyun , Hong Young-Hun , Lee Moo-Young , Chung Chin-Wook
Published: March 2020

A hysteresis loop has been observed during the E–H mode transition in an inductively coupled plasma at high pressures. The cause of the hysteresis has been reported as a nonlinearity of the transferred and dissipated powers due to capacitive coupling, multi-step ionization, the change in the electron energy probability function (EEPF), and so on [M. M. Turner and M. A. Lieberman, Plasma Sources Sci. Technol. 8(2), 313–324 (1999) and H. C. Lee and C. W. Chung, Sci. Rep. 5, 15254 (2015)]. However, when a coil current reduction is considered, the previous interpretation of hysteresis cannot explain the observations in the intermediate pressure region, where the coil current reduction occurs, but hysteresis is not observed. In this work, the E–H mode transition and its hysteresis are discussed in three pressure regions, the low, intermediate, and high pressure regions, whether or not the coil current and the hysteresis are observed. The power transfer efficiency, transferred power, EEPF, and total energy loss are obtained at 10, 100, and 300 mTorr. Hysteresis is only observed at 300 mTorr, and the coil current reduces at 100 and 300 mTorr during the E–H mode transition. The mechanism of hysteresis is explained in a power balance diagram that includes the transferred power and the dissipated power by considering the power transfer efficiency in the E and H modes. In addition, the conditions of hysteresis and coil current reduction are revealed and classified in this work.
Can second order nonlinear spectroscopies selectively probe optically “dark” surface states in small semiconductor nanocrystals?
Authors: Kelley Anne Myers
Published: March 2020

Second order nonlinear responses such as sum frequency and second harmonic generation arise from the response of a material system to the second power of an incident electromagnetic field through the material’s first hyperpolarizability or second-order optical susceptibility. These quantities are nonzero only for noncentrosymmetric systems, but different length scales of the noncentrosymmetry give rise to second harmonic or sum frequency radiation with different spatial and coherence characteristics. This perspective discusses the possible contributions to the second-order signal from films of small semiconductor quantum dots and addresses whether such experiments are expected to selectively enhance transitions to surface defects or trap states in such systems. It points out how “surface” and “bulk” contributions to the sum frequency or the second harmonic signal should be distinguishable through their angular dependence in a scattering geometry. It also explores possible mechanisms whereby second order spectroscopies might provide access to surface states that are very weak or absent in other forms of optical spectroscopy.
The effect of solvent quality on pathway-dependent solution-state self-assembly of an amphiphilic diblock copolymer
Authors: Venkataraman Shrinivas , Wei Guangmin , Mineart Kenneth P. , Hedrick James L. , Prabhu Vivek M. , Yang Yi Yan
Published: March 2020

The cholesterol-functionalized polycarbonate-based diblock copolymer, PEG113-b-P(MTC-Chol)30, forms pathway-dependent nanostructures via dialysis-based solvent exchange. The initial organic solvent that dissolves or disperses the polymer dictates a self-assembly pathway. Depending upon the initial solvent, nanostructures of disk-like micelles, exhibiting asymmetric growth and hierarchical features, are accessible from a single amphiphilic precursor. Dioxane and tetrahydrofuran (THF) molecularly dissolve the block copolymer, but THF yields disks, while dioxane yields stacked disks after dialysis against water. Dimethylformamide and methanol display dispersed disks and then form stacked disk structures after dialysis. The path-dependent morphology was correlated to solubility parameters, an understanding of which offers routes to tailor self-assemblies with limited sets of building blocks.
Charge carrier trapping by dislocations in single crystal diamond
Authors: Schreck M. , Ščajev P. , Träger M. , Mayr M. , Grünwald T. , Fischer M. , Gsell S.
Published: March 2020

Charge carrier trapping in diamond crystals containing well-defined concentrations of dislocations was investigated by several complementary techniques. Samples with dislocation densities ndis between <1 × 107 and ≈1 × 109 cm−2 were grown heteroepitaxially on Ir/YSZ/Si(001). In optical pump–probe experiments, ambipolar diffusion coefficients were determined from the decay of light-induced transient free carrier gratings. Modeling their variation with excitation density yielded trapping cross sections σ of 29 and 10 nm for the dislocations and a stress-field-induced reduction in exciton binding energies from 80 to 73 and 60 meV at ndis = 1 × 108 and 1 × 109 cm−2, respectively. The lifetime measured by induced absorption scaled proportional to 1/ndis with absolute values ranging from 0.1 to 10 ns. In the electrical measurements on two sets of detector slices, electron–hole pairs were excited by α-particles and transport was measured separately for electrons and holes. Both types of carriers showed fast transient current signals. The time constant of the additional slow component exclusively seen for holes was in agreement with the activation energy of boron acceptors. Their concentration of ≈0.5 ppb yielded σ = 1.77 × 10−13 cm2 for charged point traps. Schubweg and carrier lifetime due to deep trapping roughly reproduced the 1/ndis trend. For electrons at 3 V/μm, a value σ = 40 nm was deduced. Cross sections for holes were significantly smaller. Differences in hole trapping between the samples are attributed to charging of dislocations controlled by chemical impurities. Increase in lifetime at high voltages is explained by reduced capture cross sections for hot carriers.
A bio-inspired functional film embedded with fluorescent elastic microspheres for pressure sensing
Authors: Chen Jiawei , Liu Yingzheng , Peng Di
Published: March 2020

Developments in global pressure and shear sensors are invaluable for flow visualization and force measurement and are indispensable tools for research in fluid mechanics. Here, we introduce a bio-inspired pressure-sensitive film that has high spatial resolution and a wide measurement range. The film is embedded with fluorescent elastic microspheres that emit light under appropriate excitation. These microspheres can be compressed under external pressure, and they fully recover as pressure is released. This pressure-induced deformation causes variations in microsphere emission intensity, establishing a quantitative relationship between pressure and emission intensity. Furthermore, this film has the potential for shear-force sensing via the use of digital image correlation to measure the displacements of microspheres under shear force. This functional film has an impressively broad scope of sensing applications, such as in air-flows, underwater, and in tactile-based settings.
Ferrimagnetic semiconductor with a direct bandgap
Authors: Li Hongping , Zhu Zhipeng , Ge Zhizhong , Sun An , Tian Yi
Published: March 2020

The direct bandgap nature of semiconductors is crucial for a wide range of optoelectronic devices and energy applications. These materials are mainly concentrated in hybrid organic–inorganic halide perovskites, III–V semiconductors, and monolayer transition metal dichalcogenides. Here, we report an AA′3B2B′2O12-type direct bandgap semiconductor CaCu3Fe2Ta2O12 using spin-polarized density functional theory calculations. The formation energy indicates that this material is thermodynamically preferred under a high-temperature and high-pressure synthetic route, similar to the analog CaCu3Fe2Nb2O12. Effective ferrimagnetic interaction occurs through the antiferromagnetic coupling between the A-site Cu and B-site Fe. More importantly, CaCu3Fe2Ta2O12 exhibits semiconducting behavior with a direct bandgap in the visible range, suggesting that AA′3B2B′2O12-type quadruple perovskites are potential candidate materials in photovoltaics as well as in optoelectronic devices.
Modulation of the two-dimensional electron gas channel in flexible AlGaN/GaN high-electron-mobility transistors by mechanical bending
Authors: Wang Weijie , Chen Jie , Lundh James Spencer , Shervin Shahab , Oh Seung Kyu , Pouladi Sara , Rao Zhoulyu , Kim Ja Yeon , Kwon Min-Ki , Li Xiaohang , Choi Sukwon , Ryou Jae-Hyun
Published: March 2020

We investigate the effect of strain on the two-dimensional electron gas (2DEG) channel in a flexible Al0.25Ga0.75N/GaN high-electron-mobility transistor (HEMT) by mechanical bending to prove the concept of active polarization engineering to create multifunctional electronic and photonic devices made of flexible group III-nitride thin films. The flexible HEMTs are fabricated by a layer-transfer process and integrated with a 150-μm-thick Cu film. The strain values are estimated from high-resolution x-ray diffraction and Raman spectroscopy in 4-cm bend-down and −4-cm bend-up test conditions. The strain-induced piezoelectric polarization can alter the charge density of the 2DEG in the channel at the AlGaN/GaN interface and thus modify the output characteristics of the flexible HEMTs. Accordingly, output characteristics show an increase in output current by 3.4% in the bend-down condition and a decrease by 4.3% in the bend-up condition. Transfer characteristics show a shift of threshold voltage, which also supports the 2DEG channel modulation during bending. Computational simulation based on the same structure confirms the same current modulation effect and threshold voltage shift. Furthermore, the electrical characteristics of the flexible HEMTs show a repeatable dependence on the strain effect, which offers potential for electro-mechanical device applications.
Multiple Auger decays of core-excited states in N2
Authors: Odagiri Takeshi , Taniguchi Takuro , Kaneyasu Tatsuo , Tanaka Hirokazu , Adachi Jun-ichi , Lablanquie Pascal , Hikosaka Yasumasa
Published: March 2020

Multi-electron coincidence measurements have been performed at the photon energies for the core-to-valence (1s → π*) and core-to-Rydberg (1s → 3sσ and 3pπ) resonant excitations in N2 in order to investigate the dynamics of multiple Auger-electron emissions from these core-excited states in detail. Peaks due to slow electrons from superexcited atomic fragments are observed in the decay processes by emission of two or three Auger electrons, indicating stepwise (cascade) multiple Auger decays that involve faster dissociations than electronic relaxations. Energy partitions between the emitted electrons enable us to reveal the detailed decay mechanisms for these processes. Branching ratios among the decays by emission of one, two, or three Auger electrons and those between the simultaneous (direct) and stepwise (cascade) processes have been determined for each of the core-excited states. Branching ratios of decay channels resulting in molecular or fragment ions have also been substantiated.
30 GHz surface acoustic wave transducers with extremely high mass sensitivity
Authors: Zheng Jiangpo , Zhou Jian , Zeng Pei , Liu Yi , Shen Yiping , Yao Wenze , Chen Zhe , Wu Jianhui , Xiong Shuo , Chen Yiqin , Shi Xianglong , Liu Jie , Fu Yongqing , Duan Huigao
Published: March 2020

A nano-patterning process is reported in this work, which can achieve surface acoustic wave (SAW) devices with an extremely high frequency and a super-high mass sensitivity. An integrated lift-off process with ion beam milling is used to minimize the short-circuiting problem and improve the quality of nanoscale interdigital transducers (IDTs). A specifically designed proximity-effect-correction algorithm is applied to mitigate the proximity effect occurring in the electron-beam lithography process. The IDTs with a period of 160 nm and a finger width of 35 nm are achieved, enabling a frequency of ∼30 GHz on lithium niobate based SAW devices. Both centrosymmetric type and axisymmetric type IDT structures are fabricated, and the results show that the centrosymmetric type tends to excite lower-order Rayleigh waves and the axisymmetric type tends to excite higher-order wave modes. A mass sensitivity of ∼388.2 MHz × mm2/μg is demonstrated, which is ∼109 times larger than that of a conventional quartz crystal balance and ∼50 times higher than a conventional SAW device with a wavelength of 4 μm.
Phase reconstruction using fast binary 4D STEM data
Authors: O'Leary C. M. , Allen C. S. , Huang C. , Kim J. S. , Liberti E. , Nellist P. D. , Kirkland A. I.
Published: March 2020

We report the application of focused probe ptychography using binary 4D datasets obtained using scanning transmission electron microscopy (STEM). Modern fast pixelated detectors have enabled imaging of individual convergent beam electron diffraction patterns in a STEM raster scan at frame rates in the range of 1000–8000 Hz using conventional counting modes. Changing the bit depth of a counting detector, such that only values of 0 or 1 can be recorded at each pixel, allows one to decrease the dwell time and increase the frame rate to 12.5 kHz, reducing the electron exposure of the sample for a given beam current. Atomically resolved phase contrast of an aluminosilicate zeolite (ZSM-5) is observed from sparse diffraction patterns with isolated individual electrons, demonstrating the potential of binary ptychography as a low-dose 4D STEM technique.
Infrared-active phonon modes in single-crystal thorium dioxide and uranium dioxide
Authors: Knight Sean , Korlacki Rafał , Dugan Christina , Petrosky James C. , Mock Alyssa , Dowben Peter A. , Matthew Mann J. , Kimani Martin M. , Schubert Mathias
Published: March 2020

The infrared-active phonon modes, in single-crystal samples of thorium dioxide (ThO2) and uranium dioxide (UO2), were investigated using spectroscopic ellipsometry and compared with density functional theory. Both ThO2 and UO2 are found to have one infrared-active phonon mode pair [consisting of one transverse optic (TO) and one associated longitudinal optic (LO) mode], which is responsible for the dominant features in the ellipsometric data. At room temperature, our results for the mode pair’s resonant frequencies and broadening parameters are comparable with previous reflectance spectroscopy characterizations and density functional theory predictions. For ThO2, our ellipsometry and density function theory results both show that the LO mode broadening parameter is larger than the TO mode broadening. This signifies mode anharmonicity, which can be attributed to the intrinsic phonon–phonon interaction. In addition to the main mode pair, a broad low-amplitude impurity-like vibrational mode pair is detected within the reststrahlen band for both ThO2 and UO2. Elevated temperature measurements were performed for ThO2 in order to study the mechanisms by which the phonon parameters evolve with increased heat. The observed change in the TO resonant frequency is in excellent agreement with previous density functional calculations, which only consider volume expansion of the crystal lattice. This suggests that the temperature-dependent change in the TO frequency is primarily due to volume expansion. The change in the main mode pair’s broadening parameters is nearly linear within the temperature range of this study, which indicates the intrinsic anharmonic scattering (via cubic anharmonicities) as the main decay mechanism.
Electromagnetic properties and EMI shielding effectiveness of polymer composites reinforced with ferromagnetic particles at microwave frequencies
Authors: Drozdov A. D. , deClaville Christiansen J.
Published: March 2020

By means of the integration embedding scheme, a model is developed for the complex dielectric permittivity and magnetic permeability of polymers reinforced with ferromagnetic particles. The model takes into account the aspect ratio of particles and their aggregation into clusters. The governing equations involve six material parameters that are found by matching the experimental data on the real and imaginary parts of the dielectric permittivity and those of the magnetic permeability (four curves are fitted simultaneously for each material) of polymers filled with spherical and flake-shaped micro- and nanoparticles. Good agreement is demonstrated between the results of simulation and observations on polymers reinforced with carbonyl iron, cobalt, and FeCoNi alloy particles at microwave frequencies in the X-band of the electromagnetic spectrum. The model is applied to evaluate the effectiveness of electromagnetic interference shielding in the transmittance mode by polymer absorbers with spherical and flake-shaped particles. Numerical analysis shows that for the same effectiveness of shielding, reinforcement of polymers with flakes (instead of microspheres) allows the volume fraction of filler to be reduced by a factor of 2 to 3.
Evidence for spin swapping from modulation of transverse resistance in magnetic heterostructures with Rashba interface
Authors: Kim Heeman , Karube Shutaro , Borge Juan , Kim Junyeon , Kondou Kouta , Otani YoshiChika
Published: March 2020

We investigate the transverse response under the out-of-plane magnetic field for magnetic heterostructures with Cu/Bi2O3 or Ag/Bi2O3 Rashba interfaces. We detect opposite contributions on the transverse resistance by the Cu/Bi2O3 and Ag/Bi2O3 interfaces, which interestingly coincide well with the opposite signs of the spin/charge interconversion from the two interfaces. We suppose the opposite influences on the transverse resistance feature spin swapping occurrence of the converted spin current. The transverse spin flow emerges due to the spin swapping in both Cu and Ag layers, but the direction of the spin flow is opposed depending on the spin direction of the converted spin current.