bluuebunny/crossref_metadata_2025 huggingface dataset:
A review on the artificial neural network applications for small‐signal modeling of microwave FETs
Authors: Marinković Zlatica , Crupi Giovanni , Caddemi Alina , Marković Vera , Schreurs Dominique M.M.‐P.
Published: August 2019

The purpose of this paper is to provide a comprehensive overview of the field‐effect transistor (FET) small‐signal modeling using artificial neural networks (ANNs). To gain an in‐depth insight into how to effectively develop an ANN model, we present a comparative study on the application of the ANNs for modeling the scattering (S‐) parameters of a variety of FET technologies versus bias point, ambient temperature, and geometrical dimensions. As will be shown, the main challenge consists of identifying the most appropriate ANN model for the specific case under study. This is because the performance of an ANN‐based model can vary significantly, depending especially on the choice of the model structure and the size and parameters of the chosen ANN. In addition, the choice of the model is related directly to the behavior of the FET characteristics, which might greatly depend on the selected device technology and operating conditions. The analysis of the present comparative study allows understanding how to properly construct ANN models to perform at their best for a successful FET modeling.
Levels of advanced glycation end products in gingival crevicular fluid of chronic periodontitis patients with and without type‐2 diabetes mellitus
Authors: Akram Zohaib , Alqahtani Fawaz , Alqahtani Mana , Al‐Kheraif Abdulaziz A. , Javed Fawad
Published: August 2019

Background

It is hypothesized that levels of advanced glycation end products (AGEs) are higher in the gingival crevicular fluid (GCF) of chronic periodontitis (CP) patients with type‐2 diabetes mellitus (type‐2 DM) than controls (systemically healthy individuals without CP. The aim was to assess the levels of AGEs in the GCF of CP patients with and without type‐2 DM.

Methods

Participants were divided into three groups as follows. Group‐1: Patients with type‐2 DM and CP; group‐2: Non‐diabetic individuals with CP; group‐3: Non‐diabetic individuals without periodontal diseases. Demographic data were collected using a questionnaire. Full‐mouth plaque‐index (PI), bleeding‐on‐probing (BOP), probing depth (PD), clinical attachment loss (AL), and marginal‐bone‐loss (MBL) were assessed. Hemoglobin A1c (HbA1c) levels were recorded. The GCF was collected and levels of AGEs were assessed using standard techniques. Group comparisons were performed andP <0.05 was considered statistically significant.

Results

Ninety‐four individuals (32, 31, and 31 individuals in groups 1, 2, and 3, respectively) were included. Mean HbA1c levels were significantly higher in group‐1 than groups 2 (P <0.05) and 3 (P <0.05). The mean age of individuals in groups 1, 2, and 3 were 55.2, 51.5, and 50.7 years, respectively. The mean duration of type‐2 DM among individuals in group‐1 was 8.2 years (7 to 10 years). Levels of AGEs were detected in all the patients. The mean GCF levels of AGEs were significantly higher among patients in group‐1 (521.9 pg/mL [428.5 to 569.3 pg/mL]) (P <0.01) than groups 2 (234.84 pg/mL [216.8 to 318.9 pg/mL]) and 3 (87.2 pg/mL [75.2 to 97.8 pg/mL]). The mean GCF levels of AGEs were significantly higher among patients in group‐2 (P <0.01) than group‐3 (P <0.01).

Conclusion

The GCF levels of AGEs are higher in CP patients with type‐2 DM compared to systemically healthy individuals with and without periodontal diseases.
Interaction of Metal Ion‐Coordinated Dipeptide Complex and Ninhydrin in the Alkanediyl‐α,ω‐bis‐Type Gemini Surfactant System
Authors: Kumar Dileep , Rub Malik Abdul
Published: August 2019

In the current study, interaction of a metal ion‐coordinated dipeptide complex and ninhydrin was examined in the alkanediyl‐α,ω‐bis‐type gemini surfactant system. This work was performed as a function of reactants (ninhydrin and metal‐dipeptide complex), surfactants, temperature, and pH. Different techniques including UV–vis spectrophotometry were used to carry out the experiments. The kψ–values were evaluated in the presence of alkanediyl‐α,ω‐bis‐type gemini surfactants. A first‐order path in the metal‐dipeptide complex and a fractional‐order path in ninhydrin were noticed. To illustrate the quantitative analysis of kψ–[gemini] profiles, a pseudophase model of micelles was employed. Thermodynamic parameters were also evaluated and explained. By the observed outcomes, a probable mechanism was suggested and discussed in detail.
Poly(amidoamine) dendrimer‐coated magnetic nanoparticles for the fast purification and selective enrichment of glycopeptides and glycans
Authors: Kayili Hacı Mehmet , Ertürk Ali Serol , Elmacı Gökhan , Salih Bekir
Published: August 2019

Glycosylated proteins modulate various important functions of organisms. To reveal the functions of glycoproteins, in‐depth characterization studies are necessary. Although mass spectrometry is a very efficient tool for glycoproteomic and glycomic studies, efficient sample preparation methods are required prior to analyses. In the study, poly(amidoamine) dendrimer‐coated magnetic nanoparticles were presented for the specific enrichment and fast purification of glycopeptides and glycans. The enrichment and purification performance of the developed method was evaluated both at the glycopeptide, and the glycan level using several standard glycoprotein digests and released glycan samples. The poly(amidoamine) dendrimer‐coated magnetic nanoparticles not only showed selective affinity (Immunoglobulin G/Bovine Serum Albumin, 1/10 by weight) to glycopeptides and released glycans but also good sensitivity (0.4 ng/µL for Immunoglobulin G) for glycoproteomic and glycomic applications. Thirty‐five glycopeptides of Immunoglobulin G were detected after enrichment with poly(amidoamine) dendrimer‐coated magnetic nanoparticles. In addition, 55 18O tagged deamidated glycopeptides belonging to human plasma glycoproteome were confirmed. Finally, fifty 2‐aminobenzoic acid, and 30 procainamide‐labelled human plasma N‐glycans released from human plasma glycoproteins were determined after purifications. The results indicate that the proposed enrichment and purification method using poly(amidoamine) dendrimer‐coated magnetic nanoparticles could be simply adjusted to sample preparation methods.
Salt‐assisted liquid–liquid extraction in microchannel
Authors: Heydarzadeh Mohsen , Givianrad Mohammad Hadi , Heydari Rouhollah , Aberoomand Azar Parviz
Published: August 2019

In this study, for the first time, salt‐assisted liquid–liquid extraction was performed in a microchannel system. The proposed design is based on the increase of contact surface area between target analytes and extracting phase during the sample and extracting phase transfer in microchannel. In this method, first sample solution, extracting solvent, and salt were mixed by stirrer and simultaneously delivered into a microchannel using a syringe pump. In order to optimize the influential parameters on the extraction efficiency of the proposed method, zidovudine and tenofovir disoproxil fumarate were selected as model analytes. The main parameters such as extracting solvent and its volume, salt amount, pH of sample solution, and microchannel shape, length, and its inner diameter were investigated and optimized. Under the optimized conditions, the proposed method was linear in the range of 0.1–30 µg/mL and R2 coefficients were equal to 0.9922 and 0.9947 for zidovudine and tenofovir disoproxil fumarate, respectively. Extraction efficiency of the proposed method was compared with conventional salt‐assisted liquid–liquid extraction. The results show that the proposed design has higher extraction efficiency than conventional salt‐assisted liquid–liquid extraction. Finally, the proposed method was successfully applied for the determination of zidovudine and tenofovir disoproxil fumarate in plasma samples.
Immediate responses of multi‐focal low level laser therapy on quadriceps in knee osteoarthritis patients
Authors: Li Cyuan‐Fong , Chen Yi‐Jen , Lin Tz‐Yan , Hsiao Yu‐Hsuan , Fu Jimmy Chun‐Ming , Chen Chia‐Hsin , Lee Chia‐Ling
Published: August 2019

Low‐level laser therapy (LLLT) applying on knee osteoarthritis (OA) patients has shown positive outcomes in analgesic effect and functional recovery. However, few studies applied such therapy on large area of quadriceps muscle in these patients. The aim of this study was to evaluate immediate effect of multi‐focal LLLT on quadriceps of knee OA patients in pain and functional performance. Fifty‐one participants with knee OA were enrolled and evaluated before (T1) and immediately after intervention (T2) by knee joint pain in numeric rating scale (NRS), walking speed, timed five‐chair stands, and quadriceps strength by isokinetic dynamometer. Intervention with two multi‐focal Gallium‐Aluminum‐Arsenide laser devices, each device with 36 laser diodes (wavelength 808 ± 10 nm, continuous, mean power 50 mW, 30 minutes), applied simultaneously over bilateral quadriceps with a total dose of 180 J for each thigh. The multi‐focal LLLT significantly improved knee joint pain as measured by the NRS (54% reduction), timed five‐chair stands, and walking speed (P < .05). Knee extensor strength also increased in terms of peak torque and force of concentric and eccentric contraction as measured by isokinetic dynamometer (P < .05). In conclusion, single‐session multi‐focal LLLT on quadriceps in knee OA patients has immediate beneficial effect on knee pain reduction, quadriceps strengthening and functional performance recovery. Long‐term effect requires further investigation. Multi‐focal LLLT on quadriceps might serve as an alternative non‐invasive treatment option in these patients.
Watershed health assessment using the pressure–state–response (PSR) framework
Authors: Hazbavi Zeinab , Sadeghi Seyed Hamidreza , Gholamalifard Mehdi , Davudirad Ali Akbar
Published: August 2019

A pressure–state–response framework was customized to outline the watershed health (WH) concept. To achieve this, the watershed indicators of pressure, state (S), and response (R) were conceptualized according to 17 climatic, anthropogenic, and hydrologic criteria. Four node years of 1986, 1998, 2008, and 2014 were selected to provide a running picture of the Shazand Watershed condition. The WH index was then calculated using geometric mean of pressure, S, and R indicators and assigned a range of values varied from 0 (unhealthiest) to 1 (healthiest). (a) The main pressures on the Shazand Watershed come from climatic factors in 1998 and 2008 and human factors in all study years. (b) The climatic factor and then anthropogenic factors had the maximum effectiveness in explaining the S indicator. (c) In calculating R indicator, the anthropogenic factors in 1986 and the hydrologic factors in other study years played significant contributions. (d) The greatest percentage of the study area were assigned to moderate condition of S indicator in 1986, 1998, and 2008 with value of 42, 46, and 73%, respectively, whereas in 2014, 44 and 42% of the watershed were respectively recognized as relatively healthy and moderately healthy in terms of S indicator. (e) For the first to fourth study node years, some 53, 77, 78, and 60% of the Shazand Watershed had the relatively unhealthy condition, respectively. (f) The Shazand WH decreased about 12% during periods of 1986–1998 and 1986–2008. (g) An improving trend was also found in WH for some sub‐watersheds.
Friction stir welding of dissimilar metal joints
Authors: Zens A. , Zaeh M.F. , Marstatt R. , Haider F.
Published: August 2019

Friction stir welding is a solid‐state welding technology, which is suitable for joining dissimilar metals such as aluminium and copper. Because the solidus temperature is typically not exceeded, the formation of intermetallic phases can be reduced when compared to fusion welding processes. In friction stir welding, the intermetallic layer thickness, which determines the seam properties, is influenced by the welding temperature and is formed in correspondence with the Arrhenius law. It is typically in the range of a few hundred nanometers thick. In turn, the process temperature is determined by the process parameters, primarily the rotational speed and the feed rate of the machine tool. In this study, a temperature‐controlled friction stir welding process has been applied to lap joints of aluminium and copper. Welding experiments with various welding speeds and probe lengths were performed in order to assess the effect of the temperature‐time profile near the welding interface. The joints were investigated by tensile shear tests as well as optical microscopy and scanning electron microscopy.
Non‐biofilm‐forming commensal Staphylococcus epidermidis isolates produce biofilm in the presence of trypsin
Authors: Martínez‐García Sergio , Ortega‐Peña Silvestre , De Haro‐Cruz María De Jesús , Aguilera‐Arreola Ma. Guadalupe , Alcántar‐Curiel María Dolores , Betanzos‐Cabrera Gabriel , Jan‐Roblero Janet , Pérez‐Tapia Sonia Mayra , Rodríguez‐Martínez Sandra , Cancino‐Diaz Mario E. , Cancino‐Diaz Juan C.
Published: August 2019

Epidemiological studies comparing clinical and commensal Staphylococcus epidermidis isolates suggest that biofilm formation is a discriminant biomarker. A study showed that four non‐biofilm‐forming clinical S. epidermidis isolates could form an induced biofilm by trypsin treatment, suggesting that S. epidermidis can form biofilms in a protease‐independent way and in a trypsin‐induced way. In this study, the trypsin capacity to induce biofilm formation was evaluated in non‐biofilm‐forming S. epidermidis isolates (n = 133) in order to support this mechanism and to establish the importance of total biofilms (meaning the sum of protease‐independent biofilm and trypsin‐induced biofilm). Staphylococcus epidermidis isolates from ocular infections (OI; n = 24), prosthetic joint infections (PJI; n = 64), and healthy skin (HS‐1; n = 100) were screened for protease‐independent biofilm formation according to Christensen's method. The result was that there are significant differences (p < .0001) between clinical (43.2%) and commensal (17%) protease‐independent biofilm producers. Meanwhile, non‐biofilm‐forming isolates were treated with trypsin, and biofilm formation was evaluated by the same method. The number of commensal trypsin‐induced biofilm producers significantly increased from 17% to 79%. In contrast, clinical isolates increased from 43.2% to 72.7%. The comparison between clinical and commensal total biofilm yielded no significant differences (p = .392). A similar result was found when different isolation sources were compared (OI vs. HS‐1 and PJI vs. HS‐1). The genotype icaA−/aap+ was associated with the trypsin‐induced biofilm phenotype; however, no correlation was observed between aap mRNA expression and the level of trypsin‐induced biofilm phenotype. Studying another group of commensal S. epidermidis non‐biofilm‐forming isolates (HS‐2; n = 139) from different body sites, it was found that 70 isolates (60.3%) formed trypsin‐induced biofilms. In conclusion, trypsin is capable of inducing biofilm production in non‐biofilm‐forming commensal S. epidermidis isolates with the icaA−/aap+ genotype, and there is no significant difference in total biofilms when comparing clinical and commensal isolates, suggesting that total biofilms are not a discriminant biomarker.
Results and challenges of Cytochrome P450 2D6 (CYP2D6) testing in an ethnically diverse South Florida population
Authors: Salyakina Daria , Roy Sharmeen , Wang Weize , Oliva Mailin , Akhouri Rohan , Sotto Ileana , Mulas Nicole , Solano Rafaela , Fernández José R. , Sanchez Stephanie , Shamshad Uzma , Perlyn Chad , McCafferty‐Fernandez Jennifer
Published: August 2019

Background

This study focuses on the implementation of CYP2D6 genetic test profiling and the challenges associated with using standard pharmacogenetics panels in a diverse South Florida population.

Methods

A total of 413 participants were recruited to participate in this study through Nicklaus Children's Hospital. Buccal swabs were collected and tested using an extended CYP2D6 panel including 22 alleles. Phenotype, genotype, and allelic frequencies were compared among different racial and ethnic groups.

Results

The majority of participants (75.0%) self‐identified as Hispanics. Four alleles, CYP2D6*4, *17, *41, and *2A, showed a statistically significant difference between White Hispanics and Black Non‐Hispanics. Aggregate frequency of all alleles with decreased function varied between 2.8% and 50.0% in different racial and ethnic groups. Additionally, rare allele combinations were observed in this South Florida cohort.

Conclusions

The heterogeneity among Hispanic groups demonstrated in previous literature and by this study reflects the complexity of ethnicity and suggests that a more granular categorization is needed, one based on ancestry and migration history rather than primary language. Overall, we have determined that there are statistically significant differences in CYP2D6 allele frequencies in the distinct racial and ethnic populations of South Florida, demonstrating a unique genetic makeup within South Florida. However, overall, the frequencies of Poor Metabolizer, Normal Metabolizer, Intermediate Metabolizer, and Ultrarapid Metabolizer did not differ between racial and ethnic groups at a statistically significant level.
Lower medial thigh perforator (LMTP) propeller flap for reconstruction of soft tissue defects around the knee
Authors: Scaglioni Mario F. , Giunta Gabriele , Barth Andrè A. , Fritsche Elmar , Arvanitakis Michael
Published: August 2019

Background

Skin and soft‐tissue defects around the knee are common and their reconstruction is still challenging and argued. Thin, pliable and well‐vascularized tissues are required in order to restore the aesthetic appearance of the knee and facilitate joint function. Historically local muscle flaps were employed for the upper third of the lower limb reconstruction; however, since their introduction, different perforator flaps have been proposed for this purpose. The aim of this report is to share our clinical experience with the pedicled lower medial thigh perforator (p‐LMT) flap for the reconstruction of skin and soft tissue defects around the knee.

Patients and Methods

Between August 2013 and July 20, 2018, patients underwent pedicled LMT propeller flap reconstruction for defects around the knee. The subunits of the defects were the suprapatellar, the infrapatellar and patellar area and in two cases a full around the knee defect was reported. Cause of defects included trauma (13), tumor (4) and infection after knee operation (3) and defect sizes ranged from 4 × 3 cm2 to 7 × 8 cm2.

Results

Flap sizes ranged from 4 × 9 cm2 to 6 × 16 cm2. One to two perforators based on the superficial femoral artery or descending genicular artery were found between the septum of satorius and vastus medialis, or piercing the vastus medialis during dissection. All flaps were rotated 180° in propeller fashion. All the donor sites were primarily closed and no complication at the donor site was detected. In the two cases of the total knee soft tissue defect, a double pedicled flaps reconstruction was required. After a 6 months follow‐up, all the patients in the series achieved a full range of motion.

Conclusions

Fasciocutaneous flaps are currently the first reconstructive option for the soft tissue defects around the knee. The p‐LMT flap reconstruction in this case series achieved good aesthetic and functional outcomes and this flap may be a valuable option for the reconstruction of the small to medium soft tissue defects around the knee.
Deep learning how to fit an intravoxel incoherent motion model to diffusion‐weighted MRI
Authors: Barbieri Sebastiano , Gurney‐Champion Oliver J. , Klaassen Remy , Thoeny Harriet C.
Published: August 2019

Purpose

This prospective clinical study assesses the feasibility of training a deep neural network (DNN) for intravoxel incoherent motion (IVIM) model fitting to diffusion‐weighted MRI (DW‐MRI) data and evaluates its performance.

Methods

In May 2011, 10 male volunteers (age range, 29–53 years; mean, 37) underwent DW‐MRI of the upper abdomen on 1.5T and 3.0T MR scanners. Regions of interest in the left and right liver lobe, pancreas, spleen, renal cortex, and renal medulla were delineated independently by 2 readers. DNNs were trained for IVIM model fitting using these data; results were compared to least‐squares and Bayesian approaches to IVIM fitting. Intraclass correlation coefficients (ICCs) were used to assess consistency of measurements between readers. Intersubject variability was evaluated using coefficients of variation (CVs). The fitting error was calculated based on simulated data, and the average fitting time of each method was recorded.

Results

DNNs were trained successfully for IVIM parameter estimation. This approach was associated with high consistency between the 2 readers (ICCs between 50% and 97%), low intersubject variability of estimated parameter values (CVs between 9.2 and 28.4), and the lowest error when compared with least‐squares and Bayesian approaches. Fitting by DNNs was several orders of magnitude quicker than the other methods, but the networks may need to be retrained for different acquisition protocols or imaged anatomical regions.

Conclusion

DNNs are recommended for accurate and robust IVIM model fitting to DW‐MRI data. Suitable software is available for download.
The Role of Vitamin A in Wound Healing
Authors: Polcz Monica E. , Barbul Adrian
Published: August 2019

Vitamin A is an essential micronutrient that comes in multiple forms, including retinols, retinals, and retinoic acids. Dietary vitamin A is absorbed as retinol from preformed retinoids or as pro–vitamin A carotenoids that are converted into retinol in the enterocyte. These are then delivered to the liver for storage via chylomicrons and later released into the circulation and to its biologically active tissues bound to retinol‐binding protein. Vitamin A is a crucial component of many important and diverse biological functions, including reproduction, embryological development, cellular differentiation, growth, immunity, and vision. Vitamin A functions mostly through nuclear retinoic acid receptors, retinoid X receptors, and peroxisome proliferator‐activated receptors. Retinoids regulate the growth and differentiation of many cell types within skin, and its deficiency leads to abnormal epithelial keratinization. In wounded tissue, vitamin A stimulates epidermal turnover, increases the rate of re‐epithelialization, and restores epithelial structure. Retinoids have the unique ability to reverse the inhibitory effects of anti‐inflammatory steroids on wound healing. In addition to its role in the inflammatory phase of wound healing, retinoic acid has been demonstrated to enhance production of extracellular matrix components such as collagen type I and fibronectin, increase proliferation of keratinocytes and fibroblasts, and decrease levels of degrading matrix metalloproteinases.
Surface modification of boron nitride by bio‐inspired polydopamine and different chain length polyethylenimine co‐depositing
Authors: Wang Nan , Guo Shiyan , Liao Jun , Zhu Qing , Hu Chengyao , Huo Jichuan
Published: August 2019

We established a novel, easy, and versatile method of obtaining diverse and controllable interphases between epoxy resin and fillers. The method involved the co‐deposition of polydopamine (PDA) and polyethyleneimine (PEI) with different molecular lengths on boron nitride (BN) surface. The obtained PDA/PEI‐modified BN composites showed significantly improved mechanical properties, including tensile strength, toughness, and elongation at break. For example, the tensile strength, fracture toughness, and elongation at break of EP composite increased by 51%, 132%, and 170% compared with EP when the PEI molecular weight was 10 000, respectively. These results suggested that the interphases between BN and EP matrix can be adjusted by changing the molecular lengths of grafted modifiers, thereby offering a new method for the reasonable designing and exploitation of the BN‐based composite materials.
Recent advances in mechanical properties of biopolymer composites: a review
Authors: Sadasivuni Kishor Kumar , Saha Prosenjit , Adhikari Jaideep , Deshmukh Kalim , Ahamed M. Basheer , Cabibihan John‐John
Published: August 2019

In recent years, biopolymers are getting wide attention with the perspective of developing high‐performance biocomposites with low environmental impact owing to their unique and useful features such as abundant availability, renewability, eco‐friendliness and lightweight. Biopolymer composites are expected to replace many conventional materials in optical, biological, and engineering applications as the investment and research on these materials increase substantially. The desired properties of biopolymer composites can be achieved by blending an appropriate biopolymer with suitable additives, which pave the way for polymer‐filler interaction. A variety of parameters such as chemical composition, degradation kinetics and mechanical properties of biopolymer composites can be tailored according to the application needs. The interfacial interactions between the biopolymer and the nanofiller have a significant effect on the mechanical properties of biopolymer composites. The present review is focused on the recent advances in the mechanical properties of various biopolymer composites. In the first part of this review, the unfamiliar mechanical characterization techniques such as fatigue test, nanoindentation and nondestructive testing of biopolymer composites have been discussed. In the later part, the various popular processing techniques of biocomposite fabrication have been discussed. In addition, in the conclusion section, few challenges associated with the processing and mechanical performance of biopolymer composites have been described.
Flammability, thermal stability and mechanical properties of polyvinyl alcohol nanocomposites reinforced with delaminated Ti3C2Tx (MXene)
Authors: Pan Ying , Fu Li , Zhou Qingwei , Wen Zhenan , Lin Cheng‐Te , Yu Jinhong , Wang Weiming , Zhao Hongting
Published: August 2019

Herein, Ti3C2Tx (MXene) was synthesized and mixed with polyvinyl alcohol (PVA) to fabricate PVA/MXene nanocomposites. The results confirmed that delaminated MXene was successfully synthesized. The nanocomposites were obtained via casting/evaporation method. The thermal stability was evaluated by thermogravimetric analysis (TGA). For the PVA composites with content of 2 wt% MXene (PVA‐MXene2), the thermal decomposition was retarded by approximately 20°C when the temperature was lower than 350°C compared with that of pure PVA. Moreover, the evolved gas products of the PVA/MXene composite were lower than those of pure PVA. For the first time, the flame retardancy of PVA/MXene nanocomposite was investigated using a microscale combustion calorimeter. The peak heat release rate (PHRR) and total heat release of the PVA composite were reduced by 25.7% and 25.5%, respectively, with 1 wt% of MXene. The temperatures at PHRR of PVA/MXene composites were improved with the addition of MXene. Moreover, the addition of MXene resulted in PVA composites with a higher tensile strength and elongation at break than those of a pure PVA film. The improvements in the flame retardancy, thermal and mechanical properties of PVA/MXene composites should enable a wide range of potential applications of MXenes in polymer matrices.
Quantitative assessment of the power loss of silicon PV modules by IR thermography and its dependence on data‐filtering criteria
Authors: Teubner Janine , Buerhop Claudia , Pickel Tobias , Hauch Jens , Camus Christian , Brabec Christoph J.
Published: August 2019

Reliability and quality control of photovoltaic (PV) plants increases in importance as the relevance of PV for the worldwide renewable energy production grows. In this study, a new method is presented which allows for a quantitative assessment of silicon PV module performance solely by relying on the cell temperatures measured via thermography (IR). A module temperature and power key figure are formulated and found to correlate very well with a linear relationship. The dependence of the deduced correlation's precision on measurement conditions is calculated and discussed. It facilitates decision‐making because optimal measurement conditions usually occur only very rarely, such that a compromise between data quality and measurement frequency has to be found. The power loss correlation presented in this paper may be used as part of a maintenance routine in order to ensure the best possible long‐term performance of the PV plant over its lifetime. The practical application in the field is outlined and explained.
Effect of magnetic field on the formation of Cu nanoparticles during magnetron sputtering in the gas aggregation cluster source
Authors: Vaidulych Mykhailo , Hanuš Jan , Kousal Jaroslav , Kadlec Stanislav , Marek Aleš , Khalakhan Ivan , Shelemin Artem , Solař Pavel , Choukourov Andrei , Kylián Ondřej , Biederman Hynek
Published: August 2019

Reliable production of nanoparticles (NPs) by magnetron sputtering in a gas aggregation source (GAS) is of great interest because of many potential applications. The size, shape, or structure of NPs can be tuned by the operational parameters of the GAS. In this study, fabrication of copper (Cu) NPs is investigated dependent on the magnetron magnetic field (MF)–a not much studied parameter. Decrease of the MF from 83 to 35 mT results in changes in the shape and size distribution of the NPs. MF also strongly affects the NPs deposition rate (DR). Electromagnetic trapping of the NPs in the vicinity of the magnetron target is proposed to be responsible for the changes in DR and polydispersity. The highest DR was reached at 45 mT.
Exploring alternative catalytic mechanisms of the Cas9 HNH domain
Authors: Zhao Li Na , Mondal Dibyendu , Warshel Arieh
Published: August 2019

Understanding the reaction mechanism of CRISPR‐associated protein 9 (Cas9) is crucial for the application of programmable gene editing. Despite the availability of the structures of Cas9 in apo‐ and substrate‐bound forms, the catalytically active structure is still unclear. Our first attempt to explore the catalytic mechanism of Cas9 HNH domain has been based on the reasonable assumption that we are dealing with the same mechanism as endonuclease VII, including the assumption that the catalytic water is in the first shell of the Mg2+. Trying this mechanism with the cryo‐EM structure forced us to induce significant structural change driven by the movement of K848 (or other positively charged residue) close to the active site to facilitate the proton transfer step. In the present study, we explore a second reaction mechanism where the catalytic water is in the second shell of the Mg2+ and assume that the cryo‐EM structure by itself is a suitable representation of a catalytic‐ready structure. The alternative mechanism indicates that if the active water is from the second shell, then the calculated reaction barrier is lower compared with the corresponding barrier when the water comes from the first shell.
Band Alignment of WS2/MoS2 Photoanodes with Efficient Photoelectric Responses based on Mixed Van der Waals Heterostructures
Authors: Lu Chunhui , Ma Jingyao , Si Keyu , Xu Xiang , Quan Chenjing , He Chuan , Xu Xinlong
Published: August 2019

Band alignment based on mixed van der Waals heterostructures is vital to design new types of photoanodes based on transition metal dichalcogenides. Herein, different mixed ratios of WS2/MoS2 photoanodes are made using a liquid‐phase exfoliation method. The WS2/MoS2 photoanode is characterized by high‐resolution X‐ray photoelectron spectroscopy, which suggests type‐II heterostructure with a conduction band offset of 0.54 eV and a valence band offset of 0.55 eV. Herein, it is observed that the maximum photocurrent density at the ratio WS2/MoS2 (1:1) is eight times and four times larger than pure WS2 and MoS2, respectively. The amperometric I–t, Mott–Schottky, and Nyquist measurements are used to analyze the photoelectric enhancement, which suggests efficient charge separation in the photoelectrodes and low electrode–electrolyte interface resistance. Raman spectroscopy and X‐ray diffraction spectroscopy with the mode shift confirm the charge transfer and lattice change in the mixed heterostructure. The charge density difference of WS2/MoS2 also confirms charge redistribution after heterostructure formation to accelerate charge transfer at the heterostructure interface efficiently. Herein, a cheap and easy way to design WS2/MoS2 heterojunction‐based photoanodes for photoelectrochemical devices is explained.
The influence of the concentration: Variable diffusivity on the mass transfer from a polymer into a liquid
Authors: Juncu Gheorghe
Published: August 2019

The unsteady, conjugate, mass transfer of the packaging constituents to a food product has been analysed. The system was considered motionless (hydrostatic conditions). The diffusion coefficient inside the packaging material was considered concentration variable while the diffusion coefficient inside the food product was considered constant. The mass balance equations were solved numerically. The influence of the concentration‐variable diffusivity on the mass transfer mechanism and rate was analysed for different values of the partition coefficient and packaging thickness.
Effect of chitosan and alginate beads incorporated with lavender, clove essential oils, and vanillin against Botrytis cinerea and their application in fresh table grapes packaging system
Authors: Sangsuwan Jurmkwan , Sutthasupa Sutthira
Published: August 2019

Encapsulation of clove, lavender essential oils (EOs)m and vanillin into chitosan (CH) and alginate (AL) beads was prepared using a simple oil‐entrapped emulsion to inhibit Botrytis cinerea in table grapes. The overall encapsulation efficiency of AL beads was observed to be higher than that of CH beads. The release of EO from beads depended mostly on surrounding relative humidity. The inhibition efficiency of the beads was investigated with grapes packed in a clamshell by placing a permeable sachet containing beads inside and storing at 5°C for 28 days. Visible mould growth on the control grapes and grapes packed with CH beads containing clove EO was observed on Days 21 and 28, respectively. The grapes packed with AL beads containing clove EO were free from mould until Day 28. The qualities of the grapes during storage, including the CO2 and O2 concentration in the packaging, firmness, total soluble solids, titratable acidity, ascorbic acid content, and acceptability of grapes, were evaluated. The use of CH or AL beads releasing clove EO maintained the freshness, firmness, flavour, odour, and overall acceptability of the grapes better than the control.
About Shewhart control charts to monitor the Weibull mean
Authors: Fernandes Fidel H. , Lee Ho Linda , Bourguignon Marcelo
Published: August 2019

In this paper, a new reparametrization expressed in terms of the process mean for Weibull distribution is studied; thus, the monitoring of the process mean can be made directly. Additionally, we call attention that the asymptotic control limits for
control chart by central limit theorem (CLT) may lead to a serious erroneous decision. Definitively, they can only be used to signal small/medium shifts in the process mean but with a very very large sample size. We present guidelines for practitioners about the minimum sample size needed to match out‐of‐control average run length (ARL1) with the exact and asymptotic control limits in function of the shape parameter after an extensive simulation study. The proposed schemes are applied to monitoring the Weibull mean parameter of the strength distribution of a carbon fibber used in composite materials.
Tunable Open‐Access Microcavities for Solid‐State Quantum Photonics and Polaritonics
Authors: Li Feng , Li Yiming , Cai Yin , Li Peng , Tang Haijun , Zhang Yanpeng
Published: August 2019

Optical microcavities are powerful platforms widely applied in quantum information and integrated photonic circuits, among which the open‐access microcavity is a newly emerging cavity structure consisting of a micro‐sized concave mirror and a planar mirror controlled individually by groups of nanopositioners, whilst light emitters can be grown or transferred at the antinode of the cavity optical modes. Compared with monolithic microcavities, the open‐access microcavity enables the simultaneous realization of small mode volume, large‐range tunability, flexible structural engineering, and easiness for integration with external emitters, exhibiting extensive applications in the fields of solid‐state quantum photonics and polaritonics over the last decade. This review first introduces the basic theory and the construction methods of open‐access microcavities, followed by the recent advances of their applications in exciton‐polaritons, photon condensates, quantum light sources, and nanoparticle sensing.
Avalanche Carrier Multiplication in Multilayer Black Phosphorus and Avalanche Photodetector
Authors: Jia Jingyuan , Jeon Jaeho , Park Jin‐Hong , Lee Byoung Hun , Hwang Euyheon , Lee Sungjoo
Published: August 2019

A highly sensitive avalanche photodetector (APD) is fabricated by utilizing the avalanche multiplication mechanism in black phosphorus (BP), where a strong avalanche multiplication of electron–hole pairs is observed. Owing to the small bandgap (0.33 eV) of the multilayer BP, the carrier multiplication occurs at a significantly lower electric field than those of other 2D semiconductor materials. In order to further enhance the quantum efficiency and increase the signal‐to‐noise (S/N) ratio, Au nanoparticles (NPs) are integrated on the BP surface, which improves the light absorption by plasmonic effects. The BP–Au‐NPs structure effectively reduces both dark current (≈10 times lower) and onset of avalanche electric field, leading to higher carrier multiplication, photogain, quantum efficiency, and S/N ratio. For the BP–Au‐NPs APD, it is obtained that the external quantum efficiency (EQE) is 382 and the responsivity is 160 A W‐1 at an electric field of 5 kV cm‐1 (Vd ≈ 3.5 V, note that for the BP APD, EQE = 4.77 and responsivity = 2 A W‐1 obtained at the same electric field). The significantly increased performance of the BP APD is promising for low‐power‐consumption, high‐sensitivity, and low‐noise photodevice applications, which can enable high‐performance optical communication and imaging systems.
Highly Oriented Thin Films of 2D Ruddlesden‐Popper Hybrid Perovskite toward Superfast Response Photodetectors
Authors: Han Shiguo , Yao Yunpeng , Liu Xitao , Li Bingxuan , Ji Chengmin , Sun Zhihua , Hong Maochun , Luo Junhua
Published: August 2019

2D hybrid perovskites have shown great promise in the photodetection field, due to their intriguing attributes stemming from unique structural architectures. However, the great majority of detectors based on this 2D system possess a relatively low response speed (≈ms), making it extremely urgent to develop new candidates for superfast photodetection. Here, a new organic–inorganic hybrid perovskite, (PA)2(FA)Pb2I7 (EFA, where PA is n‐pentylaminium and FA is formamidine), which features the 2D Ruddlesden–Popper type perovskite framework that is composed of the corner‐sharing PbI6 octahedra is reported. Significantly, photodetectors fabricated on highly oriented thin films, which exhibit a perfect orientation parallel to 2D inorganic perovskite layers, exhibit a superfast response time up to ≈2.54 ns. To the best of the knowledge, this figure‐of‐merit catches up with that of the top‐ranking commercial materials, and sets a new record for 2D hybrid perovskite photodetectors. Moreover, extremely high photodetectivity (≈1.73 × 1014 Jones, under an incident power intensity of ≈46 µW cm−2), considerable switching ratios (>103), and low dark current (≈10 pA) are also achieved in the detector, indicating its great potential for high‐efficiency photodetection. These results shed light on the possibilities to explore new 2D candidates for assembling future high‐performance optoelectronic devices.
Bioinspired Mechanically Robust Metal‐Based Water Repellent Surface Enabled by Scalable Construction of a Flexible Coral‐Reef‐Like Architecture
Authors: Luo Xiao‐Tao , Li Chang‐Jiu
Published: August 2019

Mechanical robustness is a central concern for moving artificial superhydrophobic surfaces to application practices. It is believed that bulk hydrophilic materials cannot be use to construct micro/nanoarchitectures for superhydrophobicity since abrasion‐induced exposure of hydrophilic surfaces leads to remarkable degradation of water repellency. To address this challenge, the robust mechanical durability of a superhydrophobic surface with metal (hydrophilic) textures, through scalable construction of a flexible coral‐reef‐like hierarchical architecture on various substrates including metals, glasses, and ceramics, is demonstrated. Discontinuous coral‐reef‐like Cu architecture is built by solid‐state spraying commercial electrolytic Cu particles (15–65 µm) at supersonic particle velocities. Subsequent flame oxidation is applied to introduce a porous hard surface oxide layer. Owing to the unique combination of the flexible coral‐reef‐like architecture and self‐similar manner of the fluorinated hard oxide surface layer, the coating surface retains its water repellency with an extremely low roll‐off angle (<2°) after cyclic sand‐paper abrasion, mechanical bending, sand‐grit erosion, knife‐scratching, and heavy loading of simulated acid rain droplets. Strong adhesion to glass, ceramics, and metals up to 34 MPa can be achieved without using adhesive. The results show that the present superhydrophobic coating can have wide outdoor applications for self‐cleaning and corrosion protection of metal parts.
A Novel Theranostic Nanoprobe for In Vivo Singlet Oxygen Detection and Real‐Time Dose–Effect Relationship Monitoring in Photodynamic Therapy
Authors: Wang Han , Wang Zhaohui , Li Yongkuan , Xu Tian , Zhang Qi , Yang Man , Wang Peng , Gu Yueqing
Published: August 2019

Singlet oxygen, as the main member of reactive oxygen species, plays a significant role in cancer photodynamic therapy. However, the in vivo real‐time detection of singlet oxygen remains challenging. In this work, a Förster resonance energy transfer (FRET)‐based upconversion nanoplatform for monitoring the singlet oxygen in living systems is developed, with the ability to evaluate the in vivo dose–effect relationship between singlet oxygen and photodynamic therapy (PDT) efficacy. In details, this nanoplatform is composed of core–shell upconversion nanoparticles (UCNPs), photosensitizer MC540, NIR dye IR‐820, and poly(acryl amine) PAA‐octylamine, where the UCNPs serve as an energy donor while IR‐820 serves as an energy acceptor. The nanoparticles are found to sensitively reflect the singlet oxygen levels generated in the tumor tissues during PDT, by luminescence intensity changes of UNCPs at 800 nm emission. Furthermore, it could also enable tumor treatment with satisfactory biocompatibility. To the best knowledge, this is the first report of a theranostic nanoplatform with the ability to formulate the in vivo dose–effect relationship between singlet oxygen and PDT efficacy and to achieve tumor treatment at the same time. This work might also provide an executable strategy to evaluate photodynamic therapeutic efficacy based on singlet oxygen pathway.
Topological charge fluctuations in the Glasma
Authors: Guerrero-Rodríguez Pablo
Published: August 2019

Abstract

The early-time evolution of the system generated in ultra-relativistic heavy ion collisions is dominated by the presence of strong color fields known as Glasma fields. These can be described following the classical approach embodied in the Color Glass Condensate effective theory, which approximates QCD in the high gluon density regime. In this framework we perform an analytical first-principles calculation of the two-point correlator of the divergence of the Chern-Simons current at proper timeτ= 0+, which characterizes the early fluctuations of axial charge density in the plane transverse to the collision axis. This object plays a crucial role in the description of anomalous transport phenomena such as the Chiral Magnetic Effect. We compare our results to those obtained under the Glasma Graph approximation, which assumes gluon field correlators to obey Gaussian statistics. While this approach proves to be equivalent to the exact calculation in the limit of short transverse separations, important differences arise at larger distances, where our expression displays a remarkably slower fall-off than the Glasma Graph result (1/r4vs. 1/r8power-law decay). This discrepancy emerges from the non-linear dynamics mapping the Gaussianly-distributed color source densities onto the Glasma fields, encoded in the classical Yang-Mills equations. Our results support the conclusions reached in a previous work, where we found indications that the color screening of correlations in the transverse plane occurs at relatively large distances.
Worldline formalism for a confined scalar field
Authors: Corradini Olindo , Edwards James P. , Huet Idrish , Manzo Lucas , Pisani Pablo
Published: August 2019

Abstract

The worldline formalism is a useful scheme in quantum field theory which has also become a powerful tool for numerical computations. The key ingredient in this formalism is the first quantization of an auxiliary point-particle whose transition amplitudes correspond to the heat-kernel of the operator of quantum fluctuations of the field theory. However, to study a quantum field which is confined within some boundaries one needs to restrict the path integration domain of the auxiliary point-particle to a specific subset of worldlines enclosed by those boundaries. We show how to implement this restriction for the case of a scalar field confined to the D-dimensional ball under Dirichlet and Neumann boundary conditions, and compute the first few heat-kernel coefficients as a verification of our construction. We argue that this approach could admit different generalizations.
Four-point conformal blocks with three heavy background operators
Authors: Alkalaev Konstantin , Pavlov Mikhail
Published: August 2019

Abstract

We study CFT2 Virasoro conformal blocks of the 4-point correlation function

$$ \left\langle {\mathcal{O}}_L{\mathcal{O}}_H{\mathcal{O}}_H{\mathcal{O}}_H\right\rangle $$

O
L

O
H

O
H

O
H

with three background operators

$$ \mathcal{O} $$

O

H
and one perturbative operator

$$ \mathcal{O} $$

O

L
of dimensions Δ
L
/Δ
H
≪ 1. The conformal block function is calculated in the large central charge limit using the monodromy method. From the holographic perspective, the background operators create AdS
3 space with three conical singularities parameterized by dimensions Δ
H
, while the perturbative operator corresponds to the geodesic line stretched from the boundary to the bulk. The geodesic length calculates the perturbative conformal block. We propose how to address the block/length correspondence problem in the general case of higher-point correlation functions

$$ \left\langle {\mathcal{O}}_L\cdots {\mathcal{O}}_L{\mathcal{O}}_H\cdots {\mathcal{O}}_H\right\rangle $$

O
L

⋯

O
L

O
H

⋯

O
H

with arbitrary numbers of background and perturbative operators.