bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation of a carbon fibre-reinforced carbon aerogel and its application as a high-temperature thermal insulator
Authors: Zhang Haiming , Feng Junzong , Li Liangjun , Jiang Yonggang , Feng Jian
Published: May 2022

A carbon fiber reinforced carbon aerogel (CF/CA) was prepared by impregnating polyacrylonitrile (PAN) fibre felts with a resorcinol (R)–furfural (F) sol containing a salt (ZnCl2), followed by ageing and pyrolysis. The RF sol containing the salt was synthesized by direct polymerisation of R and F in methanol (MeOH) using ZnCl2 as a salt template. Compared with the traditional sol–gel method for preparing CF/CAs, this procedure eliminates the need for solvent-exchange and supercritical-fluid drying processes. This novel strategy may lead to lower-cost and large scale industrial processes of CF/CAs.
Novel SLIPS based on the photo-thermal MOFs with enhanced anti-icing/de-icing properties
Authors: Fang Xinzuo , Liu Yufan , Lei Sheng , Li Chuangquan , Ou Junfei , Amirfazli Alidad
Published: May 2022

The novel SLIPS based on photo-thermal MOFs exhibits an efficient and energy-saving active and passive anti/de-icing ability under light irradiation.
The oxidation state in low-valent beryllium and magnesium compounds
Authors: Gimferrer Martí , Danés Sergi , Vos Eva , Yildiz Cem B. , Corral Inés , Jana Anukul , Salvador Pedro , Andrada Diego M.
Published: May 2022

This article examines the electronic structure of group 2 (E = Be and Mg) ligand stabilized compounds. We elaborate on the donor–acceptor interaction L(0) ⇆ E(0) ⇆ L(0) and diradical L(−1) → E(+2) ← L(−1) pictures to assess the oxidation state of the metal.
Optimally designed solvent system for lignocellulosic biomass conversion supported by property predictions
Authors: Karacasulu Kaan , Echtermeyer Alexander , Kabatnik Christoph , Scheffczyk Jan , Bardow André , Viell Jörn , Mitsos Alexander
Published: May 2022

A computational screening combined with experimental biomass conversion shows that GVL-based hydrolysis can be designed to optimality and the conventionally selected co-solvent toluene would result in higher process operating costs than ethylbenzene.
Scaling mechanical instabilities in drying micellar droplets
Authors: Dewangan Jayant K , Basu Nandita , Chowdhury Mithun
Published: May 2022

We show that instabilities in drying micellar aqueous droplets generate a rich variety of heterogeneous patterns that scale with the deposited materials’ thickness, substrate-dependent-modulus, along with the solution concentration and droplet size.
Tunable two-step shape and dimensional changes with temperature of a PNIPAM/CNC hydrogel
Authors: Xu Yinghao , Ajji Abdellah , Heuzey Marie-Claude
Published: May 2022

Tailoring a bilayer hydrogel's 3D deformation by utilizing the CNCs’ constraint effect on PNIPAM in a nano-sized fibrous structure.
Hypertension induces gonadal macrophage imbalance, inflammation, lymphangiogenesis, and dysfunction
Authors: Navaneethabalakrishnan Shobana , Wilcox Brooke K. , Goodlett Bethany L. , Murphy Malea M. , Mitchell Brett M.
Published: May 2022

Hypertension (HTN) is associated with gonadal dysfunction and impaired reproductive health in both men and women. An imbalance in the systemic and renal proinflammatory (M1)/anti-inflammatory (M2) macrophage ratio, increased inflammation, and inflammation-associated lymphangiogenesis have been observed in animals with HTN. However, the impact of HTN on gonadal macrophages, inflammation, and lymphatics remains obscure. We hypothesized that salt-sensitive HTN (SSHTN) and HTN alters gonadal macrophage polarization, which is associated with inflammation, inflammation-associated lymphangiogenesis, and reproductive dysfunction. Flow cytometry analyses revealed a significant increase in M1 macrophages in the testes of SSHTN and nitro-L-arginine methyl ester hydrochloride (L-NAME)-induced HTN (LHTN) mice, with a concurrent decrease in M2 macrophages in SSHTN mice yet an increase in M2 macrophages in LHTN mice. Ovaries from SSHTN mice exhibited an increase in M1 and a decrease in M2 macrophages, while ovaries from LHTN mice had a significant increase in M2 and a decrease in M1 macrophages. Gene expression patterns of proinflammatory cytokines revealed gonadal inflammation in all hypertensive mice. Increased lymphatic vessel density in the gonads of both male and female hypertensive mice was confirmed by immunofluorescence staining for lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1). HTN adversely affected the expression pattern of steroidogenic enzymes, hormone receptors, and secretory proteins in both the testes and ovaries. In line with these results, male hypertensive mice also presented with decreased sperm concentration, and increased percentage of sperm with abnormal morphology, damaged acrosome, and nonfunctional mitochondrial activity. These data demonstrate that HTN alters gonadal macrophage polarization, which is associated with gonadal inflammation, inflammation-associated lymphangiogenesis, and dysfunction.
Multi‐layer random walker image segmentation for overlapped cervical cells using probabilistic deep learning methods
Authors: Mahyari Tayebeh Lotfi , Dansereau Richard M.
Published: May 2022

A method for overlapping cell image segmentation is presented with a focus on multi‐layer image processing in a three‐phase scheme. In the first phase, a convolutional neural network is developed to provide a coarse cell segmentation with multiple output layers to identify cell cytoplasm, locations of cell nuclei, and the background, all as probabilistic image maps for the layer outputs. In the second phase, the probabilistic image maps from the convolutional neural network are used to identify locations of cell nuclei and cell cytoplasm. Then, multi‐layer random walker image segmentation is used with cell nuclei as hard initial seeds and the cytoplasm estimates as soft seeds in a diffusion graph‐based segmentation of the cells. With rough cell segmentation from both the trained convolutional neural network and the multi‐layer random walker graph‐based technique, a third phase combines and refines the cell segmentation using the Hungarian algorithm to optimise the assignment of individual pixel locations for the final cell segmentation. We evaluate the proposed method on cervical cell images generated from the International Symposium on Biomedical Imaging 2014 dataset with results that give a Dice similarity coefficient of 97.2% (compared to 93.2% for competitors) when trained on the generated dataset.
Intelligent train operation based on deep learning from excellent driver manipulation patterns
Authors: Xu Kai , Tu Yongchao , Xu Wenxuan , Wu Shixun
Published: May 2022

In the application of deep learning to realize intelligent train operation, there are some problems, such as the single learning task. Especially when using the gradient descent approach to optimize the structure, weight and threshold of a deep network, it is easy in this task to fall into a local optimum. This leads to excessive reliance on manual tuning experience. Aiming at the above issues, this paper proposes a new approach of train manipulation and prediction based on a long short‐term memory (LSTM) deep network. From the perspective of automatic hyper‐parameter optimization, the gradient‐free intelligent search method is principally chosen to optimize the architecture and parameters of a LSTM deep network, so as to improve the manipulation accuracy based on learning from excellent drivers. This method first selects excellent driver data through the Pareto dominance principle and crowding distance calculation; on this basis, a step‐by‐step method is used to optimize the structure, weight and threshold of the LSTM network. Particularly, in the first step, we adopt a genetic algorithm to search for the optimal deep network structure, which overcomes the problem that the structure is difficult to determine. In the second step, we optimize the parameters of the deep network, a process that is divided into two stages of ‘rough learning’ and ‘precise learning’. In the ‘rough learning’ stage, we use the multi‐population chained multi‐agent (MPCMA) algorithm to preliminarily optimize the LSTM network parameters. In the ‘precise learning’ stage, the Adam algorithm is applied to further finely optimize the network parameters. Finally, through simulation experiments, it is verified that the proposed method improves the accuracy of train manipulation and prediction, and shows strong robustness in situations of multiple manipulation sequences and different temporary speed limits.
New insight into the Bibliometric Analysis on the Topic of Environmental Kuznets Curve
Authors: Xia Libo , Wang Zhiliang , Du Shuang , Tian Decun , Zhao Sujun
Published: May 2022

The topic of the environmental Kuznets curve (EKC) was searched on Web of Science and 2, 747 documents were obtained from 2010 to 2020. Among them, 2616 documents were selected and analysed using the bibliometrix package in the R language. Results showed that Environmental Science and Pollution Research were the most literature sources, and the country with the most researches was China. Keywords analysis revealed that most researches were focused on the EKC, economic development, and carbon dioxide (CO2) emission, and the last item was the main environmental pollution problem. Most researches were focused on income distribution, benefits, ecological footprint, globalization, and degradation evidence. Dividing these documents into three stages with 2014 and 2018 as the nodes, economic growth was focused from 2010 to 2014, following was focused on emissions and then the international tourism from 2019 to 2020. EKC was easily visualized among the co-citation network of authors, the co-occurrence network of keywords and the cooperation network of countries. EKC historical graph showed that the global environment should be considered as a whole to research environmental pollution and economic development, and more research should be focused on the EKC related to clean energy and sustainable development. Therefore, by analysing a large number of documents and using scientific measurement methods, it is convenient for future research on the EKC hypothesis.
Overview of Phytoremediation Technology for Heavy Metal Contaminated Soil
Authors: Li Can , Yang Guomin , Liu Zhuojun , Cai Jinxing
Published: May 2022

Phytoremediation of heavy metal polluted soil has become an efficient and environment-friendly method. The main mechanisms of phytoremediation consist of phytoextraction, phytovolatilization phytostabilization, and phytotransformation. But there are some limitations in the actual remediation effect of plants enriching heavy metals. At present, a wealth of joint remediation methods have been carried out. This paper reviewed the phytoremediation mechanisms and the research status of phytoremediation, such as Cd, As and Pb, and put forward the research direction of phytoremediation and the combination with other technologies.
Adsorption Performance of Glyphosate on Modified Shell Powder/Ce-N-Tio2
Authors: Zhang Wei , Liang Zhe , Lin Hai , Shu Jinkai , Wang Aihe
Published: May 2022

Glyphosate is a typical dissolved organic phosphorus that can cause adverse effects on plants, animals, and humans. Modified shell powder/Ce-N-TiO2 was synthesized by high-temperature doping, and the prepared modified shell powder/Ce-N-TiO2 was characterized and used response surface methodology to find out the optimum condition for adsorption removal rate. The zeta characterization indicates that the doping of Ce shifts the isotropic potential of the material to the right. The FT-IR and XPS characterization indicated that glyphosate was successfully adsorbed, and the two-two interactions of pH, contact time and dosing amount had a more obvious effect on adsorption by response surface analysis. The process of glyphosate adsorption by modified shell powder/Ce-N-TiO2 was consistent with the quasi-secondary kinetic model and Langmuir model, and the maximum adsorption amount was 66.98 mg/g. The above results may be useful for the study of other systems of glyphosate wastewater treatment.
A Study of Phosphate Solubilizing Capacity by Penicillium Aurantiogriseum under Different Carbon and Nitrogen Resources
Authors: Hu Jun , Wang Liyan , Zhang Liangliang , Gao Hongjian , Tian Da
Published: May 2022

Phosphate-solubilizing fungi have been successfully applied to the release of phosphorus from insoluble tricalcium phosphate. A phosphate-solubilizing fungi Penicillium aurantiogriseum was isolated and investigated the phosphorus solubilizing capacity under different carbon and nitrogen resources. The highest released phosphorus content reached 1000 mg/L in ammonium and sucrose conditions. Carbon resources did not limit the release of phosphorus by Penicillium aurantiogriseum. However, nitrate and urea significantly reduced the phosphorus release, which had a low phosphorus content (~780 mg/L). Glucose and ammonium were more efficient for fungal growth and organic acid secretion. Oxalic acid secreted by Penicillium aurantiogriseum dominated the release of phosphorus. The formed calcium oxalate promoted the dissolution of tricalcium phosphate. This study indicated that the effective utilization of Penicillium aurantiogriseum to dissolve tricalcium phosphate need to support more ammonium nitrogen.
Adsorption of Tetracycline by Ammonium Molybdate Modified Chinese Fir Biochars
Authors: Lu Caimei , Zhang Hanbing , Tang Rui , Yu Sishan , Li Zehua
Published: May 2022

Tetracycline (TC) adsorption amount on original wood biochar was finitely, so modification is imperative to improve its adsorption capacity. This study mixed chinese fir sawdust with ammonium molybdate to prepare a modified chinese fir biochar (MCB) via pyrolysis at 800 °C. Meanwhile, pristine chinese fir biochar (CB) was produced as control. The effects of pH, adsorption time, initial concentration and adsorbent dosage on the adsorption process were also studied. Langmuir model and quasi second-order kinetic model were used describe the characteristics of adsorption process. The optimally capacity of TC adsorption on MCB reached 36 mg/g, which was 6 – fold increase to CB. Therefore, modification by ammonium molybdate can be used as a potential way of chinese fir sawdust biochar for increasing adsorption capacity of TC from antibiotic sewage water.
Validation of the German Inflammatory Bowel Disease Fatigue (IBD-F) Questionnaire
Authors: Scholz Karina Antonia Magdalena , Thomann Anne Kerstin , Teich Niels , Baumann Hartmut , Walldorf Jens , Büning Carsten , Rosania Rosa , Canbay Ali , Arnim Ulrike von
Published: May 2022

Introduction Fatigue is a common symptom in patients with inflammatory bowel diseases (IBD). To date, there is no instrument to assess IBD-specific fatigue in German. The aim of this study was to translate the IBD Fatigue (IBD-F) scale and to test its psychometric properties in a German IBD population.

Methods After completing the translation process, 20 IBD patients participated in a pilot testing phase. For further analyses, 180 IBD patients with fatigue answered the IBD-F (Sections I, II, III) and the IBD Questionnaire (IBDQ-D). Reliability was tested by using Cronbach's alpha and corrected item–total correlation. Exploratory factor analyses (EFA) were carried out. Spearman’s correlation was calculated between the IBD-F and IBDQ-D . 78 patients could be included to calculate the test–retest reliability.

Results The German version of the IBD-F shows high face and content validity. Internal consistency was excellent, with a Cronbach's alpha of 0.93–0.98. Corrected item–total correlations ranged from 0.51 to 0.89. The correlation between the IBD-F and the IBDQ-D was statistically significant for Section I (rs=-0.59; p<0.01) and Section II (rs=-0.76; p<0.01) of the IBD-F. The EFA identified one relevant factor for each section. Test-retest reliability was acceptable for Section I (intraclass correlation coefficient (ICC)=0.73) and Section II (ICC=0.84).

Conclusion The German version of the IBD-F is a reliable and valid tool to assess fatigue in IBD.
Exploration of Core Genes in ACTH-Independent Macronodular Adrenal
Hyperplasia
Authors: Li Junwu , Wang Yunhui , Li Qinke , Zhang Ronggui
Published: May 2022

This study explores the core genes involved in the pathogenesis of
ACTH-independent macronodular adrenal hyperplasia (AIMAH), so as to provide
robust biomarkers for the clinical diagnosis and treatment of this disease. Gene
Expression Omnibus (GEO) database was used to obtain GSE25031 microarray
dataset. R package “limma” was applied to identify
differentially expressed genes (DEGs) between AIMAH and normal samples. The
Database for Annotation, Visualization and Integrated Discovery (DAVID) was
employed to perform Gene Ontology (GO) annotation for the DEGs, and Kyoto
Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis was
conducted. A protein-protein interaction network (PPI) was constructed using the
STRING online website and visualized using the Cytoscape software. The key
modules and hub genes were then identified. Finally, Gene Set Enrichment
Analysis (GSEA) enrichment analysis was carried out to find the signaling
pathways of significant clinical value in AIMAH. A total of 295 DEGs between
AIMAH and healthy samples were screened out, including 164 upregulated genes and
131 downregulated genes. Combining enrichment analysis and PPI network
construction, there were 5 signifiant pathways and 10 hub genes, among which 3
genes (FOS, FOSB, and DUSP1) were identified as potential core genes of clinical
significance in AIMAH. In conclusion, the 3 core genes, FOS, FOSB, and DUSP1,
identified here might be potential biomarkers for AIMAH, and the current study
is of guiding significance for clinical diagnosis and treatment of this
disease.
Adrenal Surgery in the Era of Multidisciplinary Endocrine Tumor
Boards
Authors: Chiapponi Costanza , Santos Daniel Pinto Dos , Hartmann Milan Janis Michael , Schmidt Matthias , Faust Michael , Wahba Roger , Bruns Christiane Josephine , Schultheis Anne Maria , Alakus Hakan
Published: May 2022

Work up of adrenal masses includes assessment of endocrine activity and
malignancy risk. There is no indication for surgical removal of nonfunctional
adrenal adenomas, according to the guidelines. In the present study, we aimed at
evaluating the impact of a university endocrine tumor board on the quality of
the indications for adrenal surgery at our institution. One hundred consecutive
patients receiving primary adrenal surgery at the University Hospital of
Cologne, Germany were included. Their demographics, clinic-pathologic
characteristics, treatment and outcome were analyzed. In 55 (55%) cases,
indication for surgery consisted in functional benign tumors, including Conn,
Cushing adenomas and pheochromocytomas. Forty (40%) tumors were referred
to surgery for malignancy suspicion and 5 (5%) myelolipomas were removed
due to their size. Eighty-nine percent of surgeries were performed as minimally
invasive procedures. Overall morbidity included two (2%) self-limiting
pancreatic fistulas after left laparoscopic adrenalectomy for pheochromocytoma.
All functional tumors were confirmed benign by final histology. Only 33
(82.5%) of 40 suspicious cases turned out to be malignant. Consequently,
nonfunctional benign adenomas were “unnecessarily” removed in
only 7 (7%) patients, with 6 (85.7%) of them having a history of
extra-adrenal cancer and all of them fulfilling criteria for surgery, according
to the international guidelines. In conclusion, the endocrine tumor board
provided an excellent adherence to the guidelines with most surgeries being
performed either for functional or malignant tumors. In nonfunctional tumors
with history of extra adrenal cancer, CT guided biopsy might be considered for
obviating surgery.
Physiological Functions of FBW7 in Metabolism
Authors: Zhang Jianmei , Kong De-huan , Huang Xiaocheng , Yu Rongbo , Yang Yachao
Published: May 2022

FBW7 is the recognition subunit of the SCF (Skp1-Cullin1-F-box proteins) E3
ubiquitin ligase complex, and it determines the specificity of the SCF
substrate. SCFFBW7 is a recognized tumor suppressor because of its ability to
degrade many proto-oncogenic substrates. Recent studies have shown that FBW7
plays a key role in metabolism by targeting the degradation of critical
regulators involved in cellular metabolism in a ubiquitin-dependent manner.
Here, we review recent studies, which highlight the important role of FBW7 in
metabolism.
Differences in Training Characteristics Between Junior, Under 23 and
Professional Cyclists
Authors: Gallo Gabriele , Leo Peter , March Manuel Mateo , Giorgi Andrea , Faelli Emanuela , Ruggeri Piero , Mujika Iñigo , Filipas Luca
Published: May 2022

The aim was to compare the training characteristics of junior, under 23 and
professional road cyclists. Training data collected during the 2019 competitive
season of thirty male cyclists, divided into three age-related categories (JUN;
U23; PRO), were retrospectively analyzed for training characteristics, external
and internal training load. Higher duration per training session were observed
in PRO (2.6±0.3 h) compared to both U23 (2.2±0.3 h;
P<0.001) and JUN (2.0±0.2 h; P<0.001).
Elevation gain per distance was higher in PRO (13.8±1.9
m·km−1) compared to U23 (10.6±0.9
m·km−1; P=0.001) and JUN
(6.7±0.3 m·km-1; P<0.001), and in U23
compared to JUN (P<0.001). Annual total work was lower in JUN
(3694±467 kJ·kg−1) compared to U23
(5268±746 kJ·kg−1; P=0.001)
and PRO (5759±1103 kJ·kg−1;
P<0.001). eTRIMP per hour was higher in JUN (151±40)
compared to both U23 (115±23; P=0.003) and PRO
(112±22; P=0.013). JUN spent more training time at medium
and high heart rate intensity zones compared to U23 and PRO
(P<0.05).
Acetylenic Esters in Organic Synthesis
Authors: Hajinasiri Rahimeh
Published: May 2022

Activated acetylenic substrates such as acetylenic esters and alkyl propiolates are very important in organic synthesis. Due to their electron deficiency, these compounds are widely used in combinatorial and multicomponent reactions, enabling the synthesis of a large variety of novel compounds. In addition, these substrates are powerful Michael acceptors and convenient dienophiles and dipolarophiles in Diels–Alder and 1,3-dipolar cycloaddition reactions. The addition of different nucleophiles, primarily phosphorus, nitrogen or sulfur, to the triple bonds of these substrates produces key intermediates, such as Tebby and Huisgen zwitterions, which can lead to designing pathways toward the generation of spirocyclic and polycyclic compounds. This account highlights recent studies on the chemistry of acetylenic esters and their applications in organic synthesis.

1 Introduction

2 Synthesis of Acyclic and Monocyclic Compounds

3 Synthesis of Spirocyclic Compounds

4 Synthesis of Polycyclic Compounds

5 Conclusion
Synthesis of Peptide N-Acylpyrroles via Anodically Generated N,O-Acetals
Authors: Malins Lara R. , Lin Yutong
Published: May 2022

An electrochemical approach to peptide C-terminal N-acylpyrroles is described from readily accessible C-terminal hydroxyproline-containing peptides, prepared via standard Fmoc solid-phase peptide synthesis (Fmoc-SPPS). Following electrochemical decarboxylation, the reactive hydroxyproline-derived N,O-acetal intermediate is aromatized under mild acidic conditions, which enable concomitant deprotection of amino acid side-chain protecting groups. The resulting peptide N-acylpyrrole is amenable to late-stage peptide modifications, including reduction with NaBH4 to deliver a valuable C-terminal peptide aldehyde motif.
Therapeutic Gases and Inhaled Anesthetics as Adjunctive Therapies in Critically Ill Patients
Authors: Gianni Stefano , Valsecchi Carlo , Berra Lorenzo
Published: May 2022

The administration of exogenous oxygen to support adequate gas exchange is the cornerstone of respiratory care. In the past few years, other gaseous molecules have been introduced in clinical practice to treat the wide variety of physiological derangement seen in critical care patients.

Inhaled nitric oxide (NO) is used for its unique selective pulmonary vasodilator effect. Recent studies showed that NO plays a pivotal role in regulating ischemia-reperfusion injury and it has antibacterial and antiviral activity.

Helium, due to its low density, is used in patients with upper airway obstruction and lower airway obstruction to facilitate gas flow and to reduce work of breathing.

Carbon monoxide (CO) is a poisonous gas that acts as a signaling molecule involved in many biologic pathways. CO's anti-inflammatory and antiproliferative effects are under investigation in the setting of acute respiratory distress and idiopathic pulmonary fibrosis.

Inhaled anesthetics are widely used in the operative room setting and, with the development of anesthetic reflectors, are now a valid option for sedation management in the intensive care unit.

Many other gases such as xenon, argon, and hydrogen sulfide are under investigation for their neuroprotective and cardioprotective effects in post-cardiac arrest syndrome.

With all these therapeutic options available, the clinician must have a clear understanding of the physiologic basis, therapeutic potential, and possible adverse events of these therapeutic gases. In this review, we will present the therapeutic gases other than oxygen used in clinical practice and we will describe other promising therapeutic gases that are in the early phases of investigation.
Use of a Digital Hearing Aid with Directional Microphones in School-aged Children
Authors: Kuk Francis K. , Kollofski Cindy , Brown Sherry , Melum Arla , Rosenthal Amy
Published: May 2022

The efficacy of a digital hearing aid with a directional microphone was examined in a school-aged population. Twenty children (9 with a mild-to-moderately-severe hearing loss and 11 with a moderate-to-severe hearing loss) between 71/2 and 132/3 years of age wore the study hearing aids binaurally for 30 days prior to the evaluation. The testing protocol included speech recognition tests using the CID W-22 word lists presented at 72 dB SPL, 65 dB SPL, and 52 dB SPL (at 0° azimuth) in the presence of a 65 dB SPL party noise (180° azimuth). Subjective rating of hearing aid efficacy in the classroom was examined using the Listening Inventory For Education (LIFE) questionnaire. Parental impression on hearing aid efficacy was also collected at the end of the study. The results showed improved speech recognition in noise with the digital directional hearing aid at all presentation levels. Preference for the digital directional hearing aids over the subjects' own omnidirectional analog hearing aids was also seen on the LIFE questionnaire and parental impression. The degree of hearing loss did not seem to have affected the benefits offered by the digital directional hearing aids. These results were compared to results from other studies on the use of directional microphones in hearing aids.

Abbreviations: BTE = behind the ear, CT = compression threshold, Dl = directivity index, HINT = Hearing In Noise Test, LIFE = Listening Inventory For Education, SNR = signal-to-noise ratio, WDRC = wide dynamic range compression
Influence of phonon-assisted tunneling on photovoltaic properties of BaSi2 and BaGe2 p–n homojunction solar cell devices
Authors: Mamindla Ramesh , Niranjan Manish K.
Published: May 2022

The solar cell properties of crystalline BaSi2 and BaGe2 p–n homojunctions are explored using density functional theory combined with a nonequilibrium Green function method. In particular, the quantitative estimates of solar cell parameters such as photocurrent, open-circuit voltage (Voc), short-circuit current (|Jsc|), and efficiency (η) are obtained for LDA and GGA-1/2 functionals. The effect of temperature on solar cell parameters is included through electron–phonon coupling (EPC) using the special thermal displacements method. The magnitudes of Jsc, Voc, and η for BaSi2 (BaGe2) at 300 K are found to be 27.35 mA/cm2 (26.1 mA/cm2), 0.84 V (0.78 V), and 18.0% (16.6%), respectively. Our study strongly suggests that the phonon-assisted photon absorption and thereby EPC significantly affect the photocurrent, and its inclusion is necessary for a proper description of various solar cell parameters. The computed solar cell parameters for BaSi2 (BaGe2) p–n homojunctions can be used as benchmark ab-initio quantum mechanical results and can be used in simulations based on continuum models.
Phonon transport in the gigahertz to terahertz range: Confinement, topology, and second sound
Authors: Vasileiadis Thomas , Reparaz Juan Sebastian , Graczykowski Bartlomiej
Published: May 2022

Transport of heat and hypersound with gigahertz (GHz) to terahertz (THz) phonons is crucial for heat management in electronics, mediating signal processing with microwave radiation, thermoelectrics, and various types of sensors based on nanomechanical resonators. Efficient control of heat and sound transport requires new materials, novel experimental techniques, and a detailed knowledge of the interaction of phonons with other elementary excitations. Wave-like heat transport, also known as second sound, has recently attracted renewed attention since it provides several opportunities for overcoming some of the limitations imposed by diffusive transport (Fourier’s regime). The frequency-domain detection of GHz-to-THz phonons can be carried out in a remote, non-destructive, and all-optical manner. The ongoing development of nanodevices and metamaterials made of low-dimensional nanostructures will require spatially resolved, time-resolved, and anisotropic measurements of phonon-related properties. These tasks can be accomplished with Brillouin light scattering (BLS) and various newly developed variants of this method, such as pumped-BLS. In the near future, pumped-BLS is expected to become useful for characterizing GHz topological nanophononics. Finally, second-sound phenomena can be observed with all-optical methods like frequency-domain thermoreflectance.
Dynamic mass isolation method utilized in self-moving precision positioning stage for improved speed performance
Authors: Liao Xinxin , He Qingbo , Feng Zhihua
Published: May 2022

The method of dynamic mass isolation is utilized in a self-moving precision positioning stage actuated by a piezostack to increase its moving speed. Two prototypes, namely, the referenced stage and the modified stage, have been fabricated. The only difference between the two stages is the flexure hinge manufactured in the modified stage to achieve an efficient dynamic mass isolation method. The step response has been investigated. The modified stage with dynamic mass isolation presents the average displacement of 6.6 µm with the applied step voltage being 55 V. By contrast, the referenced stage without dynamic mass isolation presents the average displacement of 1.6 µm. As a type of quasi-static piezoactuator/motors, the modified stage moves approximately four times faster than the referenced stage under the same driving frequency. By utilizing the dynamic mass isolation method, the modified stage still features the advantages of the referenced stage, such as cost-effective controllers, heavy-load capability, and motion of nanoscale. The concept and technique presented in this study can be applied to precision positioning stages for improved speed performance.
Atomic-scale investigation of implanted Mg in GaN through ultra-high-pressure annealing
Authors: Uzuhashi Jun , Chen Jun , Kumar Ashutosh , Yi Wei , Ohkubo Tadakatsu , Tanaka Ryo , Takashima Shinya , Edo Masaharu , Sierakowski Kacper , Bockowski Michal , Sakurai Hideki , Kachi Tetsu , Sekiguchi Takashi , Hono Kazuhiro
Published: May 2022

An area selective doping via ion implantation is a key technology to realize gallium nitride (GaN) based energy-efficient power devices; however, conventional annealing leads to the formation of numerous Mg-enriched defects, which result in inefficient p-type activation. The recent invention of ultra-high-pressure annealing (UHPA) has enabled a significant improvement in p-type activation efficiency. In this study, we investigated the formation of Mg-enriched defects in Mg implanted GaN followed by annealing under either conventional atmospheric pressure or ultra-high-pressure. Unlike the conventional annealing, UHPA leads to a much lower number density of Mg-enriched defects. Correlative scanning transmission electron microscopy, atom probe tomography, cathodoluminescence, and secondary ion mass spectrometry analyses have shown that the number density of Mg-enriched defects is substantially suppressed by the UHPA. The dissolved Mg concentrations in the GaN matrix for both the conventional and the UHPA samples are almost of the same value, approximately 2 × 1018 cm−3; however, the UHPA sample shows over one order of magnitude stronger intensity of donor–acceptor-pair emission than the conventional one. Thus, the implanted Mg is effectively activated as acceptors through the UHPA technique.
Grid inhomogeneous solvation theory for cross-solvation in rigid solvents
Authors: Waibl Franz , Kraml Johannes , Hoerschinger Valentin J. , Hofer Florian , Kamenik Anna S. , Fernández-Quintero Monica L. , Liedl Klaus R.
Published: May 2022

Grid Inhomogeneous Solvation Theory (GIST) has proven useful to calculate localized thermodynamic properties of water around a solute. Numerous studies have leveraged this information to enhance structure-based binding predictions. We have recently extended GIST toward chloroform as a solvent to allow the prediction of passive membrane permeability. Here, we further generalize the GIST algorithm toward all solvents that can be modeled as rigid molecules. This restriction is inherent to the method and is already present in the inhomogeneous solvation theory. Here, we show that our approach can be applied to various solvent molecules by comparing the results of GIST simulations with thermodynamic integration (TI) calculations and experimental results. Additionally, we analyze and compare a matrix consisting of 100 entries of ten different solvent molecules solvated within each other. We find that the GIST results are highly correlated with TI calculations as well as experiments. For some solvents, we find Pearson correlations of up to 0.99 to the true entropy, while others are affected by the first-order approximation more strongly. The enthalpy-entropy splitting provided by GIST allows us to extend a recently published approach, which estimates higher order entropies by a linear scaling of the first-order entropy, to solvents other than water. Furthermore, we investigate the convergence of GIST in different solvents. We conclude that our extension to GIST reliably calculates localized thermodynamic properties for different solvents and thereby significantly extends the applicability of this widely used method.
Micro-defect imaging with an improved resolution using nonlinear ultrasonic Lamb waves
Authors: Li Weibin , Xiao Jun , Deng Mingxi
Published: May 2022

Ultrasonic inspection is a widely used nondestructive testing approach in industrial fields for more accurate life prediction and efficient management strategies of critical structural components. However, it is quite challenging to detect a kind of micro-defect, whose size is much smaller than the ultrasonic wavelength but larger than the ultrasonic amplitude (namely, there is no appearance of non-classical acoustic nonlinearity). In this article, identification and imaging of a micro-defect of this size range with an improved resolution is conducted by the combination of the second-harmonic generation (SHG) of ultrasonic Lamb waves and the reconstruction algorithm for the probability inspection of damage. An intuitive model is first developed to explore the physical mechanism of a micro-defect-induced variation of generated second harmonic of a primary Lamb wave in a plate. Variations of amplitudes of second harmonics generated in propagation paths are used to construct the micro-defect image. A phase-reversal technique is employed to enhance the signal-to-noise ratio of the SHG. Comparisons between images constructed by linear and nonlinear acoustic features of Lamb wave propagation are presented. Results show that the image of the micro-defect with an improved resolution is successfully obtained by the proposed approach, while there is no visualized result obtained by the conventional linear ultrasonic one.
Edge turbulence measurements in L-mode and I-mode at ASDEX Upgrade
Authors: Bielajew R. , Conway G. D. , Griener M. , Happel T. , Höfler K. , Howard N. T. , Hubbard A. E. , McCarthy W. , Molina Cabrera P. A. , Nishizawa T. , Rodriguez-Fernandez P. , Silvagni D. , Vanovac B. , Wendler D. , Yoo C. , White A. E. ,   ASDEX Upgrade Team
Published: May 2022

The I-mode confinement regime is promising for future reactor operation due to high energy confinement without high particle confinement. However, the role of edge turbulence in creating I-mode's beneficial transport properties is still unknown. New measurements of edge turbulence (ρpol=0.9−1.0) in L-modes and I-modes at low and high densities at ASDEX Upgrade are presented in this paper. A high radial resolution correlation electron cyclotron emission radiometer measures the broadband turbulence throughout the L-mode and I-mode edge and pedestal. The weakly coherent mode (WCM) is measured in both L-mode and I-mode near the last closed flux surface with Te fluctuation levels of 2.3%–4.2%, with a frequency shift between the two phases related to a deeper Er well in I-mode. An neTe phase diagnostic captures a change of the WCM neTe phase between L-mode and I-mode from −171° to −143°. The thermal He beam diagnostic measures a WCM wavenumber range of −0.5 to −1.0 cm−1. A low-frequency edge oscillation (LFEO) appears in the I-mode phase of these discharges and displays coupling to the WCM, but the LFEO does not appear in the L-mode phase. Linear gyrokinetic simulations of the outer core and pedestal top turbulence indicate that while the dominant turbulent modes in the outer core are ion directed and electrostatic, the turbulence becomes increasingly electron directed and electromagnetic with increasing radius. Collisionality is not found to impact characteristics of the L-mode and I-mode edge turbulence with respect to the presence of the WCM; however, the quality of global confinement decreases with collisionality.
OptiBoost: A method for choosing a safe and efficient boost for the bond-boost method in accelerated molecular dynamics simulations with hyperdynamics
Authors: Cui Jianming , Fichthorn Kristen A.
Published: May 2022

Accelerated molecular-dynamics (MD) simulations based on hyperdynamics (HD) can significantly improve the efficiency of MD simulations of condensed-phase systems that evolve via rare events. However, such simulations are not generally easy to apply since appropriate boosts are usually unknown. In this work, we developed a method called OptiBoost to adjust the value of the boost in HD simulations based on the bond-boost method. We demonstrated the OptiBoost method in simulations on a cosine potential and applied it in three different systems involving Ag diffusion on Ag(100) in vacuum and in ethylene glycol solvent. In all cases, OptiBoost was able to predict safe and effective values of the boost, indicating that the OptiBoost protocol is an effective way to advance the applicability of HD simulations.
Drag reduction due to nonionic-type surfactants in turbulent pipe flow of ethylene glycol aqueous solution
Authors: Tamano Shinji , Taga Keijiro , Watanabe Taku , Matsui Yuki , Morinishi Yohei , Yamada Toru
Published: May 2022

The drag-reducing effects of two nonionic-type surfactants, oleyl-N, N-dimethylamine N-oxide (ODMAO) and octadecyl-N, N-bis(2-hydroxyethyl)amine N-oxide (C18BAO), in ethylene glycol (EG) aqueous solution were comprehensively investigated at various surfactant concentrations of up to 2000 ppm by weight at various solution temperatures ranging from −5 to 80 °C in turbulent pipe flows. In EG aqueous solution (30% by weight), the mixture of ODMAO with salicylic acid with a molar ratio of 0.2 could effectively reduce the turbulent drag in the low-temperature range (up to 40 °C), whereas the effect of C18BAO was more notable at a temperature higher than 40  °C. Furthermore, the mixture of ODMAO and C18BAO in EG aqueous solution exhibited a high drag reduction ratio of more than 60% in a considerably wider range of solution temperatures (from 20 to 60 °C), while the drag reduction performance deteriorated below 0 °C and beyond 60 °C.
Xanthophyll-cycle based model of the rapid photoprotection of Nannochloropsis in response to regular and irregular light/dark sequences
Authors: Short Audrey H. , Fay Thomas P. , Crisanto Thien , Hall Johanna , Steen Collin J. , Niyogi Krishna K. , Limmer David T. , Fleming Graham R.
Published: May 2022

We explore the photoprotection dynamics of Nannochloropsis oceanica using time-correlated single photon counting under regular and irregular actinic light sequences. The varying light sequences mimic natural conditions, allowing us to probe the real-time response of non-photochemical quenching (NPQ) pathways. Durations of fluctuating light exposure during a fixed total experimental time and prior light exposure of the algae are both found to have a profound effect on NPQ. These observations are rationalized with a quantitative model based on the xanthophyll cycle and the protonation of LHCX1. The model is able to accurately describe the dynamics of non-photochemical quenching across a variety of light sequences. The combined model and observations suggest that the accumulation of a quenching complex, likely zeaxanthin bound to a protonated LHCX1, is responsible for the gradual rise in NPQ. Additionally, the model makes specific predictions for the light sequence dependence of xanthophyll concentrations that are in reasonable agreement with independent chromatography measurements taken during a specific light/dark sequence.
Rotational excitation of NS+ by H2 revisited: A new global potential energy surface and rate coefficients
Authors: Bop C. T. , Kalugina Y. , Lique F.
Published: May 2022

Due to the lack of specific collisional data, the abundance of NS+ in cold dense interstellar clouds was determined using collisional rate coefficients of CS as a substitute. To better understand the chemistry of sulfur in the interstellar medium, further abundance modeling using the actual NS+ collisional rate coefficients is needed. For this purpose, we have computed the first full 4D potential energy surface of the NS+–H2 van der Waals complex using the explicitly correlated coupled cluster approach with single, double, and non-iterative triple excitation in conjunction with the augmented-correlation consistent-polarized valence triple zeta basis set. The potential energy surface exhibits a global minimum of 848.24 cm−1 for a planar configuration of the complex. The long-range interaction energy, described using multipolar moments, is sensitive to the orientation of H2 up to radial distances of ∼50 a0. From this new interaction potential, we derived excitation cross sections, induced by collision with ortho- and para-H2, for the 15 low-lying rotational levels of NS+ using the quantum mechanical close-coupling approach. By thermally averaging these data, we determined downward rate coefficients for temperatures up to 50 K. By comparing them with the previous NS+–H2 data, we demonstrated that reduced dimensional approaches are not suited for this system. In addition, we found that the CS collisional data underestimate our results by up to an order of magnitude. The differences clearly indicate that the abundance of NS+, in cold dense clouds retrieved from observational spectra, must be reassessed using these new collisional rate coefficients.
Exponential decay of correlations in the one-dimensional Coulomb gas ensembles
Authors: Turova Tatyana S.
Published: May 2022

We consider the Gibbs measure on the configurations of N particles on R+ with one fixed particle at one end at 0. The potential includes pair-wise Coulomb interactions between any particle and its 2K neighbors. Only when K = 1, the model is within the rank-one operators, and it was treated previously. Here, for the case K ≥ 2, exponentially fast convergence of density distribution for the spacings between particles is proved when N → ∞. In addition, we establish the exponential decay of correlations between the spacings when the number of particles between them is increasing. We treat in detail the case K = 2; when K > 2, the proof works in a similar manner.
The density–temperature range of exchange–correlation exciton existence by the fermionic path integral Monte Carlo method
Authors: Filinov V. S. , Levashov P. R. , Larkin A. S.
Published: May 2022

A recently developed fermionic path integral Monte Carlo approach [Filinov et al., Phys. Rev. E 102, 033203 (2020) and Filinov et al., J. Phys. A 55, 035001 (2021)] has been applied for the estimation of the density–temperature range of exchange–correlation exciton existence in a strongly coupled degenerate uniform electron gas. The approach allows us to reduce the “fermionic sign problem” taking into account the interference effects of the Coulomb and exchange interaction of electrons in the basic Monte Carlo cell and its periodic images. Our results for radial distribution functions demonstrate the formation and decay of a short-range quantum ordering of electrons associated with exchange–correlation excitons in the literature. Such excitons have never been observed earlier in standard path integral Monte Carlo simulations.
Quantum dynamics of the photoinduced charge separation in a symmetric donor–acceptor–donor triad: The role of vibronic couplings, symmetry and temperature
Authors: Picconi David
Published: May 2022

The photoinduced charge separation in a symmetric donor–acceptor–donor (D–A–D) triad is studied quantum mechanically using a realistic diabatic vibronic coupling model. The model includes a locally excited DA*D state and two charge-transfer states D+A−D and DA−D+ and is constructed according to a procedure generally applicable to semirigid D–A–D structures and based on energies, forces, and force constants obtained by quantum chemical calculations. In this case, the electronic structure is described by time-dependent density functional theory, and the corrected linear response is used in conjunction with the polarizable continuum model to account for state-specific solvent effects. The multimode dynamics following the photoexcitation to the locally excited state are simulated by the hybrid Gaussian-multiconfigurational time-dependent Hartree method, and temperature effects are included using thermo field theory. The dynamics are connected to the transient absorption spectrum obtained in recent experiments, which is simulated and fully assigned from first principles. It is found that the charge separation is mediated by symmetry-breaking vibrations of relatively low frequency, which implies that temperature should be accounted for to obtain reliable estimates of the charge transfer rate.
A three-dimensional small angle measurement system based on autocollimation method
Authors: Ren Wenran , Cui Jiwen , Tan Jiubin
Published: May 2022

A laser autocollimator based on transmission grating and combined reflector is proposed to simultaneously measure a three-dimensional angle. The optical configuration of the proposed autocollimator is designed, and a mathematical model for measuring a three-dimensional angle is established. The three-dimensional angle is obtained by detecting the change in the direction of the three measurement beams generated by grating diffraction and reflected by a combined reflector. The experimental setup based on the proposed autocollimator was constructed, and a series of experiments were performed to verify the feasibility of the proposed autocollimator for precision angle measurement. The experimental results showed that the measurement resolution of three-dimensional angles is better than 0.01", with measurement repeatability of yaw, pitch, and roll angles being 0.013", 0.012", and 0.009", respectively.