bluuebunny/crossref_metadata_2025 huggingface dataset:
The participation of practitioners in the process of creating and implementing education policies
Authors: Spasenović Vera , Hebib Emina , Šaljić Zorica
Published: February 2021

One of the important preconditions for the implementation of a functional education policy is that key decisions in the domain of education policy are taken following consultations with those who will be directly implementing these decisions. The aim of our research was to examine how school pedagogists perceive the participation of education practitioners in the process of creating and implementing education policies. More specifically, we sought to identify all those who participated in the creation of current reform solutions in education, and to find out to what extent education practitioners are motivated to get involved in the process of creating and implementing education policies and why. The research sample consisted of 159 pedagogists working in primary and secondary schools across the Republic of Serbia. The data, collected through a survey, indicate that practitioners, from the point of view of school pedagogists, do not take an active part in the process of shaping and implementing education policies. The experience of not taking into account the practitioners' perspective, even not giving them the opportunity to be asked for their input, contributes to reform solutions being perceived as imposed from above, non-relevant and inappropriate to the local context, which is borne out by the findings of this research. Such circumstances have a detrimental effect on education practitioners' motivation for implementing educational-political decisions and the suppression of resistance to changes.
Opinions of high school students in Serbia on the advantages of on-line learning during the Covid-19 pandemic
Authors: Vučetić Ivana , Vasojević Nena , Kirin Snežana
Published: February 2021

In recent years, there have been numerous studies and pilot-projects both in Serbia and around the world, dealing with on-line learning. This paper analyzes the possibilities of online learning theoretically and empirically. The theoretical section presents an analysis of differences between traditional and on-line learning based on a review of the literature. The empirical study was carried out using a questionnaire distributed through various internet platforms in April 2020. The survey comprised 339 high school students in Serbia who attended on-line classes during the state of emergency imposed due to the Covid-19 pandemic. The data thus collected were processed using qualitative analysis. The aim of the study was to identify the advantages of on-line learning relative to the traditional model of instruction from the perspective of secondary school students, and to offer recommendations for further research and improvements in practice. The results of the study suggest that secondary school students in Serbia recognize the advantages of on-line learning in terms of time efficiency, the possibility to manage the learning process and improvement of the results of the instructional process.
São Luís, patrimônio cultural entre ruínas, grafites e pichações:
Authors: Brasil Marcus Ramusyo de Almeida
Published: February 2021

O presente trabalho se propõe a interrogar, a partir de uma produção fotográfica e uma posterior digressão reflexiva, as relações existentes entre as ruínas do Centro Histórico de São Luís e os registros que, através de grafites e pichações/pixações, os jovens da periferia têm efetuado nas paredes, portas e janelas das casas históricas da capital do Maranhão, no Brasil. A metodologia utilizada para a produção e inventário das imagens da pesquisa se calca entre uma antropologia visual e uma antropologia da imagem. Do ponto de vista do modo de operar o pensamento, utilizo algumas ideias do filósofo Walter Benjamin (2012, 2009, 2013) sobre fotografia, rememoração e alegoria. Por fim, teço alguns comentários sobre os significados e potências estéticas/políticas dos grafites e pichações/pixações no Centro Histórico de São Luís – MA e a correspondência estabelecida com as ruínas do casario ali presente. O texto não se pretende revisionista dos temas relacionados ao grafite e pichações/pixações ao patrimônio, mas um ensaio crítico no tocante a como as artes visuais operam no contexto da correspondência entre abandono e apropriação do espaço público.
O Sertão nas artes:
Authors: Almeida Ivete Batista da Silva
Published: February 2021

Este artigo traz o tema da construção da representação social estereotipada do sertão e do sertanejo a partir da exploração da imagem do cangaço. Partindo da teoria das representações sociais de Serge Moscovici e das análises de Duval Albuquerque sobre a invenção do Nordeste, analisamos as formas e as temáticas a partir das quais a imprensa ilustrada e mesmo o cinema, dos anos de 1950, exploraram a representação do cangaço para imprimir ao sertão e ao sertanejo a imagem de selvageria, invisibilizando a cultura sertaneja e suas verdadeiras tensões sociais, reduzindo o sertanejo a um personagem estereotipado.
Novo modelo de cobrança para o uso de recursos hídricos em bacias de rio controladas por reservatórios: aplicação no sistema Engenheiro Ávidos/São Gonçalo - PB
Authors: Santos Valterlin da Silva , Silva Neto Enéas Dantas da , Curi Wilson Fadlo
Published: February 2021

O objetivo deste artigo foi aplicar um novo modelo de cobrança pelo uso de recursos hídricos superficiais em um sistema de reservatórios interdependentes no semiárido do Estado da Paraíba. O modelo aplicado apresenta características como: o uso de tarifas baseadas na sazonalidade do sistema; a possibilidade de inibir a prática de reservas e potenciais captações extras de água por parte dos usuários; a contribuição dos usuários em relação a uma parcela dos investimentos previstos na bacia hidrográfica; a diferenciação proporcional de usuários como base no volume outorgado; e o uso de subsídios quando considerado a existência de recursos hídricos oriundos da transposição de outras bacias hidrográficas. O sistema foi analisado de forma integrada via modelo de otimização multiobjetivo, considerando dois cenários possíveis: envolvendo ou não a transposição do Rio São Francisco e, duas situações distintas: outorgas com ou sem medição de vazão. Os resultados demonstraram que os valores cobrados pelo metro cúbico de água são compatíveis com a realidade local e nacional; a prática de reservas e potenciais captações extras de água por parte dos usuários oneram os valores cobrados de forma a incitar o uso mais racional da água. Constatou-se a aplicabilidade do modelo sendo possível redimensionar os valores dos parâmetros utilizados no âmbito do comitê de bacia.
Caracterização de manifestações patológicas em estações elevatórias e de tratamento de esgotos
Authors: Oliveira Diogo Botelho Correa de , Belo Paula Olivia de , Soares Willames de Albuquerque , Monteiro Eliana Cristina Barreto
Published: February 2021

O sistema de esgotamento sanitário e seus componentes são essenciais para o desenvolvimento da infraestrutura e saneamento e da qualidade de vida da população. As estruturas integradas ao funcionamento desse sistema possuem características próprias inerentes ao meio em que estão inseridas, sendo ambientalmente agressivos. A facilidade no desenvolvimento de patologias, aliada à falta de manutenção provocam diversos danos aos processos operacionais e relacionados ao tratamento de efluentes. Se previstos em projeto e tratados de forma preventiva, os gastos e energia dispendidos com estes problemas podem ser reduzidos do que se foram tratados de forma remediada. Utilizando classificação visual com a análise de registros fotográficos, objetivou-se identificar e classificar as patologias recorrentes em estações elevatórias (EE’s) e de tratamento de esgotos (ETE’s), levando em consideração sua origem (construtiva, funcional, acidental ou natural), intensidade (estética, funcional ou estrutural) e frequência. Constatou-se que a maior parte das patologias foram adquiridas, devido à classe de agressividade do ambiente, apresentando percentuais de 78,48% e 47,83%, trazendo danos estruturais das construções na faixa de 43,90% e 83,33% em ETE’s e EE’s respectivamente. Por meio de fator característico para classificação de relevância, pode-se concluir que as ETE’s são mais suscetíveis à danos de maior gravidade, atingindo com maior intensidade o sistema, em comparação às EE’s.
Avaliação do potencial para a geração de agregados carbono negativos no Brasil
Authors: Nascimento Luiza Silva do , Barbosa Kargean Vianna
Published: February 2021

As mudanças climáticas são um problema ambiental que causa crescente preocupação na sociedade. Quando se busca solucionar esta questão, diminuir as emissões de CO2 e outros gases de efeito estufa se apresenta como um grande desafio.  Diante disso, o objetivo desse trabalho foi determinar o potencial da produção de agregados para concreto carbono negativos no Brasil, utilizando CO2 capturado de usinas de etanol e escória de siderurgia como matérias primas. Essa avaliação foi conduzida através da determinação do local ideal para instalação deste empreendimento e da estimativa do custo de produção que permite a viabilidade deste produto.  Para este fim, foram listadas e mapeadas possíveis fontes de dióxido de carbono e de escória, e operações de geoprocessamento foram aplicadas a esses dados para encontrar o local mais propício para a instalação do empreendimento. 410 usinas de açúcar e etanol e 28 usinas siderúrgicas foram listadas e mapeadas. Devido à grande disponibilidade de matéria prima e a pequena distância entre as fontes, o local considerado mais propício para a instalação desse empreendimento foi Piracicaba no estado de São Paulo. O custo de produção que permite a viabilidade do projeto foi de R$: 9.742.924 reais por ano, e apesar desse valor ser baixo, com incentivos governamentais a viabilidade desse empreendimento aumentaria consideravelmente, se tornando uma alternativa para a destinação de escória e uma forma lucrativa de reduzir emissões de dióxido de carbono.
Effect of Training Program to Improve Observational Skills of Psychiatric Nursing Students
Authors: Alenezi Atallah Khalaf
Published: February 2021

Introduction: Training program is believed to enhance nursing students’ knowledge and performance in observational skills, which can be an essential factor in their future practice as nurses working in a psychiatric institution. Aim: This study aimed to assess the effect of training program for psychiatric nursing students to improve their observational skills. Materials and Methods: This study used an interventional design. The study sample included 80 nursing students undergoing clinical practice in psychiatric nursing during 2019-20 (10 months). The tools used for data collection were questionnaire to assess nursing student’s knowledge and an observational checklist to measure the performance. Percentage distribution, chi-square, and correlation coefficient were used to determine influence of training program on nursing students. Results: The training program imparted to students was effective as indicated by a highly significant difference between pre/post-training programs in all items of psychiatric nursing students’ knowledge. Furthermore, a highly significant difference between pre/post-training programs in all elements of students’ observational rating scale was also evident. Conclusion: The training program improved nursing students’ knowledge and performance. Particularly, their observational skills have brought confidence in their exposure and boast their ability in caring for their patients.
Arrhythmias and Conduction Abnormalities after Surgical Repair of Congenital Heart Disease
Authors: Lawgali Mohanad Abdulhadi Saleh , Mustafa Marium Mohamed , Feituri Rasmia H. , Halies Faiaz Ragab Salem
Published: February 2021

Aims: To recognize cardiac arrhythmias and conduction abnormalities in children who underwent a surgical repair for congenital heart disease.

Patients and Methods: One hundred thirty one (131) patients underwent a surgical repair of congenital heart disease between 2000-2018, and follow-up period after surgery was from two months to eighteen years and our data was collected over 1 year “2018”  by interview both children and parents, sixty-four patients (48.8%) were a cyanotic congenital heart disease (ACCHD),sixty-seven patients(51.1%) were cyanotic congenital heart disease (CCHD), (41.9%) were female, (58.1%) were male. Cyanotic congenital heart disease more common in male. These patients were evaluated by ECG to detect conduction abnormalities and arrhythmias, Holter monitoring in symptomatic patient.

Results: Types of abnormal heart rhythm found out by ECG, Holter monitoring, significant premature atrial contraction (PAC) in one patient post fontain, atrial fibrillation in two patients with post-operative (ASD) repaired. RBBB occur in 53 patients and was most common among post-operative (TOF) repaired (37 patients). Frequent ventricular ectopic in one patient with postoperative (TOF) repaired. Atrial tachycardia in one patient with Epstein anomaly, WPW in two patients with Epstein anomaly, complete heart blook in five patients, four of them post operative VSD repaired, one post fontain operation. Symptomatic bradycardia needs pace maker in one patient post fontan operation.

Conclusions: The Patient after repair of congenital heart defect needed follow-up for detection of arrhythmias, those with complex defect need more frequent follow-up because they prone more to arrhythmia than those with simple defect with no residual defect.
Genetic Gains to Grain Yield of Maize Varieties for Small Farmers in Brazil
Authors: Berilli Ana Paula Cândido Gabriel , Almeida Rafael Nunes de , Gottardo Luis Eduardo , Moulin Monique Moreira , Pereira Messias Gonzaga , Berilli Sávio da Silva , Vettorazzi Julio Cesar Fiorio , Trindade Roberto dos Santos , Almeida Robson Ferreira de
Published: February 2021

The demand for expanding the genetic base in working collections of older maize breeding programs points to the need to pool efforts and reaffirm methodologies for conserving genetic variability that can still be accessed in maize populations. The objective of the work was to select full sib maize progenies and to estimate genetic gains in the first cycle of reciprocal recurrent selection for common maize intended for cultivation in a region characterized by family farm, in Brazil. We evaluated 120 full sib families of maize from crossbreeding between individuals of the Cimmyt and Piranão varieties. Competition trials were conducted at two experimental stations in the state of Espírito Santo, Brazil. A randomized block design was adopted with 2 repetitions, arranged in sets. Different selection indexes were tested in order to enhance gains in productivity and prolificacy. The selection of 40 superior families made it possible to estimate a gain of 0.77 Mg ha-1 in grain productivity for producers in the region. With these results, we discussed the importance of work to improve maize populations for small producers to motivate the conservation of the genetic variability of tropical maize germplasm. Thus, from the results obtained in this study, we show the possibility of investing in technologies aimed at small producers in order to motive the conservation of genetic resources, food sovereignty of producers and, consequently, world security, given the importance of this culture for human feed.
The Impact of International Capital Flows on Economic Growth in Palestine
Authors: Badwan Nemer , Atta Mohammed
Published: February 2021

The study aims to investigate and examine the impact of International Capital Flows and other Financial Flows on Economic Growth in Palestine during the period (2007-2018). This study also included trends and methods of forming Capital Flows and Financial Capital Flows. The study used the appropriate descriptive and analytical approach by the authors for the purposes and requirements of the research to investigate the real results and required. The researchers used the time intervals method, and the study concluded that Foreign Direct Investment (FDI), Foreign Portfolio Investment (FPI), Large Loans (World Bank), Worker Remittances (WR), Foreign Affairs Borrowing and Financial Grants (GR) have a noticeable positive impact on Economic Growth in Palestine. The study made several important and useful recommendations, the most notably: That Palestinian Government must lay down and establish lighter and comfortable rules and regulations for investors to attract more investors and Foreign Investments to Palestine. Besides, the Palestinian Government must work hard side by side with the other Developed Countries for reaching better Economic Development and increasing a good rate. To achieve a good rate of Economic Growth, the government must work hard to create job opportunities for citizens to reduce the high Unemployment rate in the country. The Government should improve the standard of living and competitiveness in global markets and obtain a sufficient share in the International Financial Markets, so the Government must work to provide new opportunities for Global Markets Integration by creating a good environment to increase Economic Growth and Technology Development.
Epidemiology, Prevalence and Antimicrobial Susceptibility of Sexually Transmitted Mycoplasma hominis and Ureaplasma urealyticum Infections in Dschang, West Cameroon
Authors: Tadongfack Thomas Djifack , Nitcheu Irina Lydia Sudeu , Keubo François Roger Nguepy , Mutarambirwa Henri Donald , Tedjieu Romeo Hervis , Tatang Cyrille Tasson , Shey Delphine Ndfubu , Selabi Aline Camerl Nzeffouo
Published: February 2021

Background: Genital Mycoplasmas play a key etiological role in several urogenital diseases among both Men and Women. Just to mention the few, they are often responsible of non-gonococcal urethritis, spontaneous abortion, preterm birth, low birth weight, infertility and perinatal mortality.

Aim: The study aimed to assess the prevalence of genital infections with Mycoplasma hominis, Ureaplasma urealyticum and their co-infection, as well as the susceptibility profiles to antibiotics commonly prescribed in Dschang, Cameroon.

Study Design: This was a 5-years retrospective cross-sectional study (including data from January 1, 2015 to December 31, 2019) conducted at Saint Vincent de Paul Hospital in Dschang, Cameroon.

Methods: Data of 338 participants received at the Gyneco-obstetric and Internal Medicine units, properly recorded, were collected from the Hospital Microbiology Laboratory records.

Results: The overall prevalence to genital Mycoplasmas was 57.4%, with 44.4% attributed to Ureaplasma urealyticum, 5.9% to Mycoplasma hominis and 7.1% to the Co-infection with the two bacteria isolates. Josamycin was the most sensitive antibiotic against Ureaplasma urealyticum (85.3%) and the co-infection (91.7%). Mycoplasma hominis isolates were more susceptible to three fluoroquinolones and tetracyclines with an equal sensitivity rate of 80.0%. Emphasis is on the increasing resistance of co-infection towards Macrolides (83.3%). Summarily, Josamycin was the antibiotic to which genital Mycoplasmas showed the lowest resistance rate (6.2%) while the highest (62.9%) was attributed to Acetylspyramycin.

Conclusion: The implementation of health policies in Cameroon should optimize on mechanisms of diagnosis, proper treatment and monitoring the antibiotic resistance of commonly isolated genital Mycoplasmas, regarding their impact on reproductive health.
Bayesian Joint Models for Longitudinal and Survival Data
Authors: Armero Carmen
Published: February 2021

This article takes a quick look at Bayesian joint models (BJMs) for longitudinal and survival data. A general formulation for BJM is examined in terms of the sampling distribution of the longitudinal and survival processes, the conditional distribution of the random effects, and the prior distribution. Next, a basic BJM defined in terms of a mixed linear model and a Cox survival regression models is discussed, and some extensions and other Bayesian topics are briefly outlined.
Financial Crises and the Macroeconomy
Authors: Flood Mark D.
Published: February 2021

This article provides an overview of the literature on systemic financial risk and its connection to broad empirical patterns in the macroeconomy. Disruptions in the financial sector (systemic risk) can impair real economic outcomes. Historically, financial crises have played a key role in the business cycle, often triggering a general contraction of credit that initiates a phase of reduced employment and economic output.
Bayesian Analysis of Seismic Events
Authors: Rotondi R.
Published: February 2021

Earthquakes are natural disasters that can have some of the most destructive impacts on society and the environment. Also, due to the shaking of the surface of the Earth that results from sudden release of energy in the Earth lithosphere, earthquakes can trigger other natural disasters, such as volcanic eruptions, landslides, avalanches, tsunamis, and floods. The earthquake‐generation process is a complex phenomenon that manifests as nonlinear dynamics in a wide array of spatial, temporal, and size scales, which range from centimeters to thousands of kilometers, from seconds to many thousands of years, and from weak events that cannot be perceived by the population to those with a violence that wreaks destruction across entire cities. In addition, the details of the space–time dynamics are not observable, and for most events, it is just the time, location, and proxy measures of the released energy that are recorded in catalogs which show increasing quality from the historical to the recent instrumental ones. In this context, Bayesian statistics is particularly suitable to incorporate statistical uncertainty associated with parameter estimation, in addition to the inherent uncertainty that is associated with the randomness of earthquake occurrences. With the development of new computational tools in recent years, the number of applications of Bayesian statistics in seismology has increased, even if many of them do not follow fully subjective approach, but rather those defined as frequentist‐Bayes and quasi‐Bayes approaches.
Markov Chain Monte Carlo Methods, Survey with Some Frequent Misunderstandings
Authors: Robert Christian P. , Changye Wu
Published: February 2021

In this article, we review some of the most standard tools used in Bayesian computation, along with vignettes on standard misunderstandings of these approaches taken from Q & As on the forum Cross‐validated answered by the first author.
Financial Crisis of 2007–2009
Authors: Flood Mark D.
Published: February 2021

The global financial crisis of 2007–2009 is a case study in both the potential and failure of statistical measurement in economics. In the run‐up to the crisis, faulty measurement and modeling of credit risk in mortgage markets contributed to an accumulation of risk exposures, while standard macroeconometric methodologies largely failed to foresee the potential hazards. The crisis provoked a dramatic restructuring of regulatory frameworks and policy practices.
Image synthesis of monoenergetic CT image in dual‐energy CT using kilovoltage CT with deep convolutional generative adversarial networks
Authors: Kawahara Daisuke , Ozawa Shuichi , Kimura Tomoki , Nagata Yasushi
Published: February 2021

Purpose

To synthesize a dual‐energy computed tomography (DECT) image from an equivalent kilovoltage computed tomography (kV‐CT) image using a deep convolutional adversarial network.

Methods

A total of 18,084 images of 28 patients are categorized into training and test datasets. Monoenergetic CT images at 40, 70, and 140 keV and equivalent kV‐CT images at 120 kVp are reconstructed via DECT and are defined as the reference images. An image prediction framework is created to generate monoenergetic computed tomography (CT) images from kV‐CT images. The accuracy of the images generated by the CNN model is determined by evaluating the mean absolute error (MAE), mean square error (MSE), relative root mean square error (RMSE), peak signal‐to‐noise ratio (PSNR), structural similarity index (SSIM), and mutual information between the synthesized and reference monochromatic CT images. Moreover, the pixel values between the synthetic and reference images are measured and compared using a manually drawn region of interest (ROI).

Results

The difference in the monoenergetic CT numbers of the ROIs between the synthetic and reference monoenergetic CT images is within the standard deviation values. The MAE, MSE, RMSE, and SSIM are the smallest for the image conversion of 120 kVp to 140 keV. The PSNR is the smallest and the MI is the largest for the synthetic 70 keV image.

Conclusions

The proposed model can act as a suitable alternative to the existing methods for the reconstruction of monoenergetic CT images in DECT from single‐energy CT images.
Deep brain stimulation effects on verbal fluency dissociated by target and active contact location
Authors: John Kevin D. , Wylie Scott A. , Dawant Benoit M. , Rodriguez William J. , Phibbs Fenna T. , Bradley Elise B. , Neimat Joseph S. , van Wouwe Nelleke C.
Published: February 2021

Objective

Deep brain stimulation (DBS) improves motor symptoms in Parkinson’s disease (PD), but it can also disrupt verbal fluency with significant costs to quality of life. The current study investigated how variability of bilateral active electrode coordinates along the superior/inferior, anterior/posterior, and lateral/medial axes in the subthalamic nucleus (STN) or the globus pallidus interna (GPi) contribute to changes in verbal fluency. We predicted that electrode location in the left hemisphere would be linked to changes in fluency, especially in the STN.

Methods

Forty PD participants treated with bilateral DBS targeting STN (n = 23) or GPi (n = 17) completed verbal fluency testing in their optimally treated state before and after DBS therapy. Normalized atlas coordinates from left and right active electrode positions along superior/inferior, anterior/posterior, and lateral/medial axes were used to predict changes in fluency postoperatively, separately for patients with STN and GPi targets.

Results

Consistent with prior studies, fluency significantly declined pre‐ to postsurgery (in both DBS targets). In STN‐DBS patients, electrode position along the inferior to superior axis in the left STN was a significant predictor of fluency changes; relatively more superior left active electrode was associated with the largest fluency declines in STN. Electrode coordinates in right STN or GPi (left or right) did not predict fluency changes.

Interpretation

We discuss these findings in light of putative mechanisms and potential clinical impact.
Adaptive multi‐dimensional Taylor network funnel control of a class of nonlinear systems with asymmetric input saturation
Authors: Han Yu‐Qun , Li Na , He Wen‐Jing , Zhu Shan‐Liang
Published: February 2021

In view of the result and performance of control are affected by the existence of input constraints and requirements, adaptive multi‐dimensional Taylor network (MTN) funnel control problem is studied for a class of nonlinear systems with asymmetric input saturation in this paper. Firstly, the effect of asymmetric input saturation can overcome by introducing the Gaussian error function, namely, the asymmetric saturation model is represented as a simple linear model with a bounded disturbance. Secondly, MTNs are employed to approximate the unknown functions in the controller design. Then, an adaptive MTN tracking controller is developed by blends the idea of funnel control into backstepping, which can guarantee that the tracking error always meets the given prescribed performance regarding the transient and steady state responses as well as the output of system tracks the give continuous reference signal. Finally, the effectiveness of the proposed control is demonstrated using two examples.
Simple and Reliable Fabrication Method for Polydimethylsiloxane Dielectric Elastomer Actuators Using Carbon Nanotube Powder Electrodes
Authors: Wiranata Ardi , Ishii Yasuyuki , Hosoya Naoki , Maeda Shingo
Published: February 2021

Dielectric elastomer actuators (DEAs) are energy efficient, compact, and operate silently. DEAs consist of an elastomer membrane sandwiched between two stretchable electrodes. Optimizing the quality of both the elastomer and the stretchable electrodes is essential to improve the DEAs performance. Herein, novel strategies are reported to achieve fast, reliable, and low‐cost fabrication of DEAs. The strategies utilize a soft brush to directly pattern carbon nanotube (CNT) powder on the elastomer membrane and tune the mechanical and surface‐adhesiveness characteristics of a polydimethylsiloxane (PDMS) membrane by altering the mixing ratio of the curing agent and base polymer. A uniaxial engineering tensile test on PDMS indicates that a softer material is formed when less curing agent is used. The softer PDMS has a sticky surface, which allows the CNT powder to be physically bound to the surface. Field‐emission scanning electron microscopy (FE‐SEM) images prove that the strong CNT network is formed on the surface of the elastomer. The electromechanical investigation also indicates that the electrical conductivity is improved for a stickier PDMS surface. The optimal performance of PDMS 30‐1 in static and cyclic DEA tests shows that the brushing of CNT combined with soft and sticky elastomer membranes can increase the DEA performance.
Remote Switching of Elastic Movement of Decorated Ligand Nanostructures Controls the Adhesion‐Regulated Polarization of Host Macrophages
Authors: Thangam Ramar , Kim Myeong Soo , Bae Gunhyu , Kim Yuri , Kang Nayeon , Lee Sungkyu , Jung Hee Joon , Jang Jinhyeok , Choi Hyojun , Li Na , Kim Minjin , Park Sangwoo , Kim Seong Yeol , Koo Thomas Myeongseok , Fu Hong En , Jeon Yoo Sang , Ambriović‐Ristov Andreja , Song Jae‐Jun , Kim Soo Young , Park Steve , Wei Qiang , Ko Changhyun , Lee Ki‐Bum , Paulmurugan Ramasamy , Kim Young Keun , Kang Heemin
Published: February 2021

Design of materials with remote switchability of the movement of decorated nanostructures presenting cell‐adhesive Arg‐Gly‐Asp ligand can decipher dynamic cell‐material interactions in decorated ligand nanostructures. In this study, the decoration of ligand‐bearing gold nanoparticles (ligand‐AuNPs) on the magnetic nanoparticle (MNP) with varying ligand‐AuNP densities is demonstrated, which are flexibly coupled to substrate in various MNP densities to maintain constant macroscopic ligand density. Magnetic switching of upward (“Upper Mag”) or downward (“Lower Mag”) movement of varying ligand‐AuNPs is shown via stretching and compression of the elastic linker, respectively. High ligand‐AuNP densities promote macrophage adhesion‐regulated M2 polarization that inhibits M1 polarization. Remote switching of downward movement (“Lower Mag”) of ligand‐AuNPs facilitates macrophage adhesion‐regulated M2 polarization, which is conversely suppressed by their upward movement (“Upper Mag”), both in vitro and in vivo. These findings are consistent with human primary macrophages. These results provide fundamental understanding into designing materials with decorated nanostructures in both high ligand‐AuNP density and downward movement of the ligand‐AuNPs toward the substrate to stimulate adhesion‐regulated M2 polarization of macrophages while suppressing pro‐inflammatory M1 polarization, thereby facilitating tissue‐healing responses.
Insight into the Solid Electrolyte Interphase Formation in Bis(fluorosulfonyl)Imide Based Ionic Liquid Electrolytes
Authors: Jafta Charl J. , Sun Xiao‐Guang , Lyu Hailong , Chen Hao , Thapaliya Bishnu P. , Heller William T. , Cuneo Matthew J. , Mayes Richard T. , Paranthaman Mariappan Parans , Dai Sheng , Bridges Craig A.
Published: February 2021

The formation of the solid electrolyte interphase (SEI) in an ionic liquid electrolyte of 0.5 m lithium bis(fluorosulfonyl)imide (LiFSI) in 1‐ethyl‐3‐methylimidazolium bis(fluorosulfonyl)imide at high cell voltages (1.7–1.9 V) is investigated in ordered mesoporous carbon (OMC) based Li metal cells using an operando small‐angle neutron scattering (SANS) technique coupled with electrochemical impedance spectroscopy and ex situ X‐ray photoelectron spectroscopy (XPS). It is demonstrated that discharging the OMC Li metal cells to ≈2 V and holding the cell voltage constant induces a rapid current increase with time, confirming extensive reduction and SEI formation. XPS analysis reveals that LiF is formed at open cell voltage (OCV), which is attributed to the carbenes generated at the lithium negative electrode because of its reaction with EMIm cation diffusing to and initiating the reaction with FSI− anions at the carbon positive electrode. It is confirmed that the chemical reaction at OCV and electrochemical reduction at high cell voltage of the FSI− anion plays a protective role against EMIm cation co‐intercalation into the carbon positive electrode during the initial discharge. Operando SANS studies also suggest that slight differences occur in the surface composition and reaction mechanism as a function of cell voltage.
Redox Photochemistry on Van Der Waals Surfaces for Reversible Doping in 2D Materials
Authors: Huang Lingli , Yang Tiefeng , Wong Lok Wing , Zheng Fangyuan , Chen Xin , Lai Ka Hei , Liu Haijun , Thi Quoc Huy , Shen Dong , Lee Chun‐Sing , Deng Qingming , Zhao Jiong , Ly Thuc Hue
Published: February 2021

Despite the van der Waals (vdW) surfaces are usually chemically inert, un‐destructive, scalable, and reversible redox reactions are introduced on the vdW surfaces of 2D anisotropic semiconductors ReX2 (X = S or Se) facilitated by simple photochemistry. Ultraviolet (UV) light (with humid) and laser exposure can reversibly oxidize and reduce rhenium disulfide (ReS2) and rhenium diselenide (ReSe2), respectively, yielding a pronounced doping effect with good control. Evidenced by Raman spectroscopy, dynamic force microscopy, transmission electron microscopy, and X‐ray photoelectron spectroscopy, the grafting and removal of covalently functionalized oxygen groups on the perfect vdW surfaces are confirmed. The optical and electrical properties can be thereby reversibly tunable in wide ranges. Such optical direct‐writing and rewritable capability via solvent/contaminant‐free approach for chemical doping are compelling in the coming era of 2D materials.
Shape Transformable Strategies for Drug Delivery
Authors: Jia Wenfeng , Wang Yushan , Liu Rui , Yu Xiangrong , Gao Huile
Published: February 2021

In tumor therapy, nanodrug delivery systems have gained momentum in the last decade. However, its efficacy remains insufficient for clinical applications. The physical properties of nanoparticles, including size, shape, and surface characteristics, can strongly affect the delivery efficacy. Ironically, research on shape function is relatively scarce, although the nanoparticle shape greatly impacts their performance; for example, nanorods with a high aspect ratio (AR) achieve greater accumulation, but their penetration is relatively weak. Hence, rather than selecting a suitable AR to balance them, the strategy of a transformable AR (i.e., transformation) is ideal in this case. Nanoparticle transformation can be achieved by either internal stimuli (such as pH and enzymes) or external stimuli (such as light) spatially and temporally with precision, thereby dramatically enhancing the efficiency of drug delivery. Thus, nanoparticle transformation is becoming a promising prospect for improving cancer treatment. In this review, first, the effect of shape on drug delivery is summarized, then, the recently transformable drug delivery systems are reviewed, and finally, the future direction of shape‐transformable nanoparticles in tumor therapy is discussed.
Designing High‐Valence Metal Sites for Electrochemical Water Splitting
Authors: Sun Hainan , Xu Xiaomin , Song Yufei , Zhou Wei , Shao Zongping
Published: February 2021

Electrochemical water splitting is a critical energy conversion process for producing clean and sustainable hydrogen; this process relies on low‐cost, highly active, and durable oxygen evolution reaction/hydrogen evolution reaction electrocatalysts. Metal cations (including transition metal and noble metal cations), particularly high‐valence metal cations that show high catalytic activity and can serve as the main active sites in electrochemical processes, have received special attention for developing advanced electrocatalysts. In this review, heterogenous electrocatalyst design strategies based on high‐valence metal sites are presented, and associated materials designed for water splitting are summarized. In the discussion, emphasis is given to high‐valence metal sites combined with the modulation of the phase/electronic/defect structure and strategies of performance improvement. Specifically, the importance of using advanced in situ and operando techniques to track the real high‐valence metal‐based active sites during the electrochemical process is highlighted. Remaining challenges and future research directions are also proposed. It is expected that this comprehensive discussion of electrocatalysts containing high‐valence metal sites can be instructive to further explore advanced electrocatalysts for water splitting and other energy‐related reactions.
Recent Progress in 2D‐Nanomaterial‐Based Triboelectric Nanogenerators
Authors: Liu Yaqian , Ping Jianfeng , Ying Yibin
Published: February 2021

The integration of triboelectric nanogenerators (TENGs) and 2D nanomaterials brings about 2D‐nanomaterial‐based TENGs (2D‐TENGs) that promote the rapid development of self‐powered sensing systems and wearable electronics. Extraordinary physical, electronic, chemical, and optical properties of 2D nanomaterials endow 2D‐TENGs with improved output performance. This review presents the state of the art of 2D‐TENGs with respect to basic classifications, enhancement mechanisms, special advantages, output performances, and applications in energy harvesting and self‐powered sensing. Furthermore, several challenges that can impede applications of 2D‐TENGs are discussed.
Biodegradable Hydrophobic Injectable Polymers for Drug Delivery and Regenerative Medicine
Authors: Arun Yuvaraj , Ghosh Radhakanta , Domb Abraham J.
Published: February 2021

Biodegradable, hydrophobic, and injectable liquid polymers are capable of achieving the minimally invasive, sustained, and local release of drugs. These hydrophobic injectable polymers also have potential in the area of regenerative medicine where the biomaterial should be stable for a certain period and then degrade to allow the growth of cells/tissues. This review presents exclusive coverage of biocompatible hydrophobic injectable pasty or liquid polymers that can be injected without the use of any solvent for drug delivery, tissue augmentation, and regenerative medicine application. The synthesis methodologies of several major types of hydrophobic pasty polymers used in the biomedical fields and their properties with the foremost criteria to serve as injectable biomaterial for localized drug delivery and regenerative medicine is described. The hydrophobic biodegradable injectable polymers discussed are aliphatic polyesters, polycarbonates and polyanhydrides, prepared from: lactic acid, glycolic acid, caprolactone, aliphatic diols and diacids, hydroxy fatty acids, and triglycerides such as castor oil.
Passivation Properties and Formation Mechanism of Amorphous Halide Perovskite Thin Films
Authors: Rigter Susan A. , Quinn Xueying L. , Kumar Rishi E. , Fenning David P. , Massonnet Philippe , Ellis Shane R. , Heeren Ron M. A. , Svane Katrine L. , Walsh Aron , Garnett Erik C.
Published: February 2021

Lead halide perovskites are among the most exciting classes of optoelectronic materials due to their unique ability to form high‐quality crystals with tunable bandgaps in the visible and near‐infrared using simple solution precipitation reactions. This facile crystallization is driven by their ionic nature; just as with other salts, it is challenging to form amorphous halide perovskites, particularly in thin‐film form where they can most easily be studied. Here, rapid desolvation promoted by the addition of acetate precursors is shown as a general method for making amorphous lead halide perovskite films with a wide variety of compositions, including those using common organic cations (methylammonium and formamidinium) and anions (bromide and iodide). By controlling the amount of acetate, it is possible to tune from fully crystalline to fully amorphous films, with an interesting intermediate state consisting of crystalline islands embedded in an amorphous matrix. The amorphous lead halide perovskite has a large and tunable optical bandgap. It improves the photoluminescence quantum yield and lifetime of incorporated crystalline perovskite, opening up the intriguing possibility of using amorphous perovskite as a passivating contact, as is currently done in record efficiency silicon solar cells.
Statistical Piezotronic Effect in Nanocrystal Bulk by Anisotropic Geometry Control
Authors: Liu Shuhai , Han Ming , Feng Xiaolong , Yu Qiuhong , Gu Long , Wang Longfei , Qin Yong , Wang Zhong Lin
Published: February 2021

Utilizing inner‐crystal piezoelectric polarization charges to control carrier transport across a metal‐semiconductor or semiconductor–semiconductor interface, piezotronic effect has great potential applications in smart micro/nano‐electromechanical system (MEMS/NEMS), human‐machine interfacing, and nanorobotics. However, current research on piezotronics has mainly focused on systems with only one or rather limited interfaces. Here, the statistical piezotronic effect is reported in ZnO bulk composited of nanoplatelets, of which the strain/stress‐induced piezo‐potential at the crystals’ interfaces can effectively gate the electrical transport of ZnO bulk. It is a statistical phenomenon of piezotronic modification of large numbers of interfaces, and the crystal orientation of inner ZnO nanoplatelets strongly influence the transport property of ZnO bulk. With optimum preferred orientation of ZnO nanoplatelets, the bulk exhibits an increased conductivity with decreasing stress at a high pressure range of 200–400 MPa, which has not been observed previously in bulk. A maximum sensitivity of 1.149 µS m−1 MPa−1 and a corresponding gauge factor of 467–589 have been achieved. As a statistical phenomenon of many piezotronic interfaces modulation, the proposed statistical piezotronic effect extends the connotation of piezotronics and promotes its practical applications in intelligent sensing.
Rubidium Fluoride Modified SnO2 for Planar n‐i‐p Perovskite Solar Cells
Authors: Zhuang Jing , Mao Peng , Luan Yigang , Chen Ningli , Cao Xiaofei , Niu Guosheng , Jia Feifei , Wang Fuyi , Cao Shaokui , Wang Jizheng
Published: February 2021

Regulating the electron transport layer (ETL) has been an effective way to promote the power conversion efficiency (PCE) of perovskite solar cells (PSCs) as well as suppress their hysteresis. Herein, the SnO2 ETL using a cost‐effective modification material rubidium fluoride (RbF) is modified in two methods: 1) adding RbF into SnO2 colloidal dispersion, F and Sn have a strong interaction, confirmed via X‐ray photoelectron spectra and density functional theory results, contributing to the improved electron mobility of SnO2; 2) depositing RbF at the SnO2/perovskite interface, Rb+ cations actively escape into the interstitial sites of the perovskite lattice to inhibit ions migration and reduce non‐radiative recombination, which dedicates to the improved open‐circuit voltage (Voc) for the PSCs with suppressed hysteresis. In addition, double‐sided passivated PSCs, RbF on the SnO2 surface, and p‐methoxyphenethylammonium iodide on the perovskite surface, produces an outstanding PCE of 23.38% with a Voc of 1.213 V, corresponding to an extremely small Voc deficit of 0.347 V.
Intracellular Mutual Promotion of Redox Homeostasis Regulation and Iron Metabolism Disruption for Enduring Chemodynamic Therapy
Authors: Liu Yang , Zhai Shaojie , Jiang Xingwu , Liu Yanyan , Wang Kun , Wang Chaochao , Zhang Meng , Liu Xuanyong , Bu Wenbo
Published: February 2021

Intracellular redox homeostasis and the iron metabolism system in tumor cells are closely associated with the limited efficacy of chemodynamic therapy (CDT). Despite extensive attempts, maintaining high levels of intracellular catalysts (free iron) and reactants (H2O2) while decreasing the content of reactive oxygen species (ROS) scavengers (especially glutathione (GSH)) for enduring CDT still remains great challenges. Herein, SS bond‐rich dendritic mesoporous organic silica nanoparticles (DMON) are utilized as GSH‐depleting agents. After co‐loading Fe0 and a catalase inhibitor (3‐amino‐1,2,4‐triazole (AT)), a novel biodegradable nanocarrier is constructed as DMON@Fe0/AT. In the mildly acidic tumor microenvironment, on‐demand ferrous ions and AT are intelligently released. AT suppresses the activity of catalase for H2O2 hoarding, and the exposed DMON weakens ROS scavenging systems by persistently depleting intracellular GSH. The highly efficient •OH production by DMON@Fe0/AT can effectively attack mitochondria and downregulate the expression of ferroportin 1, which can disrupt the cellular iron metabolism system, leading to the desired retention of iron in the cytoplasm. More importantly, DMON@Fe0/AT exhibits a much more efficient CDT killing effect on 4T1 tumor cells than plain Fe0 nanoparticles, benefiting from their synergistic redox regulation and iron metabolism disruption. Overall, the as‐prepared intelligent, degradable DMON@Fe0/AT provides an innovative strategy for enduring CDT.
Highly Efficient Room‐Temperature Phosphorescence Based on Single‐Benzene Structure Molecules and Photoactivated Luminescence with Afterglow
Authors: Ma Liangwei , Sun Siyu , Ding Bingbing , Ma Xiang , Tian He
Published: February 2021

Recently, a remarkable advance has been made for metal‐free room‐temperature phosphorescence (RTP) crystals with high phosphorescence quantum yield. However, amorphous, especially heavy‐atom‐free, RTP materials still suffer from low quantum yield due to the transition‐forbidden character of phosphorescence and the relatively poor suppression of nonradiative transition in amorphous materials. In this study, a series of single‐benzene structure‐based high intersystem crossing yield phosphor is obtained. After embedding into polyvinyl alcohol matrix, all these phosphor exhibits efficient phosphorescence emission (ФP, up to 44.0%). Besides, photo‐switchable phosphorescence emission can be obtained by doping these molecules into a polymethyl methacrylate (PMMA) matrix. The phosphorescence can be gradually switched on by consuming the residual oxygen in the PMMA matrix under continuous UV light irradiation. Furthermore, the phosphorescence will be spontaneously switched off under ambient conditions. Taking advantage of the photoactivation character, this material has potential in information storage and anti‐counterfeiting.
Molecular Engineering of Mesogenic Constituents Within Liquid Crystalline Elastomers to Sharpen Thermotropic Actuation
Authors: McCracken Joselle M. , Donovan Brian R. , Lynch Kelsey M. , White Timothy J.
Published: February 2021

Liquid crystalline elastomers (LCE) are stimuli‐responsive materials with a distinguished mechanical response. LCE have been subject to numerous recent functional examinations in robotics, health sciences, and optics. The liquid crystallinity of the elastomeric polymer networks of LCE are largely derived from liquid crystalline monomer precursors. Recent reports have utilized commercially available liquid crystalline diacrylate monomers in chain extension reactions to prepare LCE. These reactions have been largely based on monomeric precursors originally to enhance the and thermal stability of optical films. Here, it is demonstrated that preparing LCE via a liquid crystalline diacrylate with reduced mesogen–mesogen interaction enhances and sharpens the thermotropic actuation of these materials. Robust composition‐response correlations are demonstrated in LCE prepared by three common synthetic methods. The enhanced thermotropic response of LCE prepared from this precursor increases the thermomechanical efficiency by sixfold. Accordingly, this work addresses important limitations in utilizing the thermal response of LCE in robotics, health care, and consumer goods.