bluuebunny/crossref_metadata_2025 huggingface dataset:
Revision of Alnus (Betulaceae) in Iran using molecular ITS markers and morphological characteristics
Authors: Gholamiterojeni Tahereh , Sharifnia Fariba , Nejadsattari Taher , Assadi Mostafa , Mehdi Hamdi Seyed Mohammad
Published: September 2019

Alnus (Alder) is a genus of Betulaceae, which comprises more than 29 species in the world. According to different classifications of flora, eight taxa of the genus naturally grow in Iran and are distributed along the northern slope of Albourz Mountains in Iran (Hyrcanian forests). In the current research, we investigated morphological characteristics and phylogenetic relationships of 31 populations of the genus in Iran. Twenty-eight qualitative and quantitative traits were studied for morphological evaluation and ITS molecular marker was investigated for molecular study. We used MVSP, SPSS, MrBayes, RAXMLGUI, Mesquite 2.71, Modeltest 3.7 software packages for statistical analyses. Morphological features varied widely among the studied taxa and ANOVA test revealed significant difference for most of them. Moreover, the angle of leaf base, the leaf margin shape, the length and width of the leaf blade, fruits length, and the presence of hair on the petioles, young twigs, and buds were more variable morphological traits. The studied taxa were clustered separately in the UPGMA tree, PCA and PCO plots using morphological traits. In addition, CA-joined plot showed each taxon to have distinct morphological trait(s), which is useful in the identification of the taxa. Phylogeny analysis revealed that Alnus genus is a monophyletic group. Furthermore, the studied taxa were clustered separately in phylogenetic dendrogram. According to morphological and ITS data, we listed ten taxa of the genus in Iran and introduced A. hyrcana and A. longiflorescentia as two new species from Hyrcanian forests of Iran.
Correlation between learning and alcoholization in rats
Authors: Kovalenko Olga , Bondarenko Oleksandr , Tubaltseva Irina , Makarchuk Mukola
Published: September 2019

The aim of this work was to investigate the relationship between the processes of learning and innate behaviour and alcohol abuse in young male rats. Rats differed in the degree of alcohol motivation and had different combinations of training in maze with alcoholization. In general it was found that compared to nondependent animals, alcohol-dependent rats were characterized by much higer emotionality, anxiety, lower locomotor activity, and research activity. The most negative influence of alcohol abuse on the behaviour was shown in animals with low innate activity (locomotor, emotional, and exploratory activity), which were poorly trained in the maze. It was shown that training rats in the maze before alcohol abuse had a positive effect on the behaviour (slightly reduced the amount of alcohol-preferring animals). Alcoholization before training increased the level of anxiety and neurotic reactions in animals, especially in rats, which had poorly trained in maze before alcoholization. Alcoholization of animals before the start of training increased the level of anxiety and neurotic reactions in alcoholized rats, especially in those that were poorly trained in the maze before alcoholization.
Análise espacial dos fatores determinantes das pastagens no baixo Amazonas/PA
Authors: Corrêa Jéssica Ariana de Jesus , Santos José Laurindo Campos dos , Andrade Silvia Cristina de Pádua , Costa Izaura Cristina Nunes Pereira , Silva Júlio Tota da
Published: September 2019

O presente trabalho teve por objetivo analisar a dinâmica espacial de áreas de pastagens e verificar os principais fatores que contribuem para sua distribuição na região do Baixo Amazonas nos anos de 2000 e 2014. Foi utilizada análise de regressão espacial sendo as porcentagens de pastagem como variáveis dependentes e, como variáveis independentes, fatores ambientais, de acessibilidade, políticas públicas, estrutura fundiária, economia e demográficos relacionados com a presença de pastagens. Observou-se que as áreas de pastagem em 2000 eram de 15.767,12 Km² enquanto que em 2014 aumentou para 18.657,58 Km². Além disso, os resultados mostraram que as áreas de pastagens naturais ainda são em maior proporção que áreas de pastagens cultivadas com um incremento de 0,23% em 2014 quando comparado com o ano 2000, porém as pastagens plantadads apresentaram crescimento em 11,64% de área.  A concentração das pastagens naturais estão próximas a planície de inundação, enquanto que a expansão das pastagens plantadas ocorrem em áreas com presença  de estradas e rodovias. Os resultados da análise de regressão mostraram que a porcentagem de área com a agricultura e precipitação anual foram as variáveis explicativas que se relacionaram nos dois anos para os dois tipos de pastagens. Para as pastagens plantadas a variável explicativa mais significativa foi  os estabelecimentos agropecuários com pecuária com coeficiente de -0,37 e 0,24 em 2000 e 2014, respectivamente. Verificou-se que o estabelecimento de áreas protegidas são cruciais pois atuam como barreiras para a expansão das áreas de pastagens plantadas e que, estradas e rodovias favorecem a implantação de pastagens em seu entorno. A modelagem estatística e espacialmente explícita mostrou ser uma ferramenta útil de análise para compreender os processos e padrões de mudanças de uso e cobertura da terra, em específico a distribuição das pastagens no Baixo Amazonas.
Sinais dos Tempos, uma questão hermenêutica
Authors: Suzuki Francisca Cirlena
Published: September 2019

Com alegria e esperança, lança-se luz sobre os problemas do mundo, através da Gaudium et Spes, uma Constituição Pastoral. De modo simples, a Igreja Católica olha com naturalidade o que a humanidade enfrenta nos âmbitos da vida, sejam eles econômicos, políticos e/ou sociais. O olhar da Igreja Católica Apostólica Romana se voltou para as misérias humanas, em sua concretude, durante anos de discussões em conferências, aulas e muito estudo dentro do Concílio Vaticano II sob o título de os Sinais dos Tempos. Embora o termo tenha percorrido um longo caminho e recebido muitas reelaborações, contando muitas idas e vindas em busca de um entendimento para esse termo aplicado ao mundo. Ainda assim, estabelecem-se indagações a respeito de sua hermenêutica: o que teria demandado tantas reflexões dos Padres Conciliares sobre a interpretação do termo Sinais dos Tempos? Teria sido a dificuldade encontrada em articular os significados dos Sinais dos Tempos do Papa João XXIII com os Sinais dos Tempos do Evangelho (Mt 16,3)?
Economia com justiça, solidariedade e generosidade (Dt 14:22-15:23)
Authors: Zabatiero Júlio Paulo Tavares Mantovani
Published: September 2019

Este artigo é uma exegese sócio-crítica de Deuteronômio 14:22-15:23, uma seção do chamado Código Deuteronômico, que trata especificamente das normas para a estruturação econômica da vida social. A seção propõe uma estruturação da economia baseada na ação libertadora e pactual de YHWH, construída a partir de uma releitura crítica de tradições mesopotâmicas (assírias e babilônicas) de estruturação e restauração da ordem econômica. A seção é composta de cinco normas, organizadas de forma quiástica, as quais estabelecem um tipo de economia baseada na lógica da dádiva, com vistas a tornar concreta na vida social os princípios da justiça, solidariedade e generosidade entre os membros do povo de Deus. Podese comparar esta proposta deuteronômica com o projeto de economia solidária desenvolvido por Paul Singer e outros.
Yüksek Kamu Binalarında Duman Tahliyesinin Simülasyon Metoduyla İncelenmesi
Authors: KAYA Osman , ISIKAN Mustafa Osman
Published: September 2019

Günümüzde nüfusun hızla artmasına
paralel olarak kalabalık şehirler ortaya çıkmakta ve bu şehirlere hizmet etmek
için arsa problemlerinden kaynaklı olarak dikey mimarinin bir ürünü olan yüksek
binalar yaygınlaşmaktadır. Her geçen gün değişen ve gelişim gösteren farklı
mimari tasarımların ürünü olan bu yüksek binalar; karmaşık ve kompleks
yapılardan dolayı her hangi bir yangın anında içerisindeki canlılar açısından
hayati tehlike - mal, ticari ürün, kıymetli eşyalar vs. açısından ise önemli
maddi zarar ve kayıp risklerini fazlaca taşımaktadırlar.

Bu çalışmamızda İstanbul’un İlçelerinden olan
Sancaktepe Belediyesi Hizmet Binası iki boyutlu AUTOCAD çizimi referans
alınarak PyroSim duman tahliye simülasyonu programıyla tüm bina katları çizilip
binanın üç boyutlu modeli oluşturulmuştur. Oluşturulan üç boyutlu modelde
yangın çıkma olasılığı yüksek olan otopark ve mutfak bölümlerinde sırasıyla
araç ve yağ yangını olmak üzere iki farklı yangın tipi için dört farklı yangın
senaryosu planlanmıştır. PyroSim programı yardımı ile bu dört senaryo için
meydana gelecek duman tahliyesine ilişkin üç boyutlu hız, sıcaklık ve duman
yayılımı analiz edilerek incelenmiş olup gerekli değerlendirmeler yapılmıştır.
Extraversion, Secure Attachment dan Perilaku Cyberbullying
Authors: Safaria Triantoro , Rizal Irfani
Published: September 2019

Riset-riset sebelumnya menunjukkan bahwa perbedaan individual seperti kepribadian dan gaya attachment dapat memprediksi perilaku bullying dan cyberbullying. Meski demikian, masih ditemukan adanya inkonsistensi dalam temuan-temuan sebelumnya. Penelitian ini menguji apakah dimensi kepribadian extraversion dan secure attachment berperan dalam munculnya perilaku cyberbullying. Partisipan dalam penelitian ini berjumlah 199 siswa SMP.  Analisis regresi digunakan untuk menguji hipotesis yang diajukan. Hasil penelitian ini menunjukkan bahwa rendahnya skor extraversion memprediksi tingginya skor cyberbullying. Sementara itu rendahnya skor secure attachment memprediksi tingginya skor cyberbullying. Rekomendasi dan saran dijelaskan lebih lanjut dalam artikel ini.
Perspektif Tuhan atau Manusia? Pengaruh Sudut Pandang terhadap Penilaian Bias dalam Kelompok
Authors: Rachmanputra Okky Arif , Milla Mirra Noor
Published: September 2019

Penelitian ini bertujuan untuk melihat pengaruh sudut pandang terhadap pemikiran bias dalam kelompok agama. Variabel sudut pandang terbagi atas dua variasi yaitu sudut pandang diri dan sudut pandang Ketuhanan. Penelitian ini ingin melihat apakah terdapat perbedaan antara individu yang mengaktifkan sudut pandang diri dengan sudut pandang Ketuhanan terhadap pemikiran bias dalam kelompok agama. Penelitian ini memiliki disain penelitian eksperimen. Partisipan penelitian ini adalah 81 mahasiswa dan beragama Islam. Partisipan secara acak dikelompokkan berdasarkan kondisi manipulasi penelitian, yaitu sudut pandang diri dan sudut pandang Ketuhanan. Partisipan diminta untuk menentukan apakah mereka bersedia memberikan donasi kepada panti asuhan yang merepresentasikan umat Muslim atau panti asuhan yang merepresenatsikan umat agama lain. Hasil penelitian menunjukkan bahwa tidak terdapat perbedaan pada kelompok partisipan yang mengaktifkan sudut pandang diri dengan sudut pandang Ketuhanan terhadap pemikiran bias dalam kelompok χ2 (2) = 0,240, p = 0,624 >0,05. Artinya, pada partisipan baik yang mengaktifkan sudut pandang diri maupun sudut pandang Ketuhanan, tetap memberikan donasi kepada panti asuhan yang merepresentasikan agamanya dan umat agama lain. Konteks dimana absennya keadaan konflik antar kelompok agama di Indonesia menjadi salah satu alasan yang dapat menjelaskan hasil penelitian ini.
DeepMoney: counterfeit money detection using generative adversarial networks
Authors: Ali Toqeer , Jan Salman , Alkhodre Ahmad , Nauman Mohammad , Amin Muhammad , Siddiqui Muhammad Shoaib
Published: September 2019

Conventional paper currency and modern electronic currency are two important modes of transactions. In several parts of the world, conventional methodology has clear precedence over its electronic counterpart. However, the identification of forged currency paper notes is now becoming an increasingly crucial problem because of the new and improved tactics employed by counterfeiters. In this paper, a machine assisted system—dubbed DeepMoney—is proposed which has been developed to discriminate fake notes from genuine ones. For this purpose, state-of-the-art models of machine learning called Generative Adversarial Networks (GANs) are employed. GANs use unsupervised learning to train a model that can then be used to perform supervised predictions. This flexibility provides the best of both worlds by allowing unlabelled data to be trained on whilst still making concrete predictions. This technique was applied to Pakistani banknotes. State-of-the-art image processing and feature recognition techniques were used to design the overall approach of a valid input. Augmented samples of images were used in the experiments which show that a high-precision machine can be developed to recognize genuine paper money. An accuracy of 80% has been achieved. The code is available as an open source to allow others to reproduce and build upon the efforts already made.
Nutrient availability induces community shifts in seagrass meadows grazed by turtles
Authors: Martínez López Isis Gabriela , van Den Akker Marloes , Walk Liene , van Katwijk Marieke M. , van Der Heide Tjisse , van Tussenbroek Brigitta I.
Published: September 2019

In the Caribbean, green turtles graze seagrass meadows dominated by Thalassia testudinum through rotational grazing, resulting in the creation of grazed and recovering (abandoned) patches surrounded by ungrazed seagrasses. We evaluated the seagrass community and its environment along a turtle grazing gradient; with the duration of (simulated) grazing as a proxy for the level of grazing pressure. The grazing levels consisted of Short-term (4 months clipping), Medium-term (8 months clipping), Long-term grazing (8 months of clipping in previously grazed areas), 8-months recovery of previously grazed patches, and ungrazed or unclipped patches as controls. We measured biomass and density of the seagrasses and rhizophytic algae, and changes in sediment parameters. Medium- and Long-term grazing promoted a shift in community species composition. At increasing grazing pressure, the total biomass of T. testudinum declined, whereas that of early-successional increased. Ammonium concentrations were highest in the patches of Medium-term (9.2 + 0.8 μM) and Long-term grazing levels (11.0 + 2.2 μM) and were lowest in the control areas (4.6 + 1.5 μM). T. testudinum is a late-successional species that maintains sediment nutrient concentrations at levels below the requirements of early-successional species when dominant. When the abundance of this species declines due to grazing, these resources become available, likely driving a shift in community composition toward a higher abundance of early-successional species.
Assessment of Heavy Metals Content in African Giant Rat (Cricetomys gambianus)
Authors: Atanda T. A. , Murana O. O. , Tijani O. J. , Adeyemi V. A.
Published: September 2019

This study was undertaken to evaluate the concentrations of heavy metals in the liver, kidney and tissue of Africa giant rat (Cricetomys gambianus) in three (3) processing centers in Abeokuta, Ogun State, Nigeria with a view to determine its safeness for consumption. Atomic Absorption Spectroscopy was used to determine the concentrations of heavy metals in the liver, tissue and kidney of Africa giant rat. Data collected were analyzed using descriptive and inferential statistics. The study found out that Mn, Zn and Cu are present in liver, tissue and kidney of Cricetomys gambianus while cobalt, cadmium, chromium, lead and nickel are below detection limit. Mn levels ranged between 0.015±0.002, 0.01±0.002 and 0.005±0.003 for liver, tissue and kidney respectively. Zn levels ranged between 0.070±0.016, 0.032±0.013 and0.044±0.006 for liver, tissue and kidney respectively. Cu levels ranged between 0.0087±0.0061, 0.000±0.000 and 0.0057±0.0001 for liver, tissue and kidney respectively. Highest manganese concentration was observed in the liver (0.015±0.002 mg/kg) while highest copper concentration was observed in the liver (0.0087±0.0061 mg/kg).The levels of heavy metals in the liver, tissue and kidney ranged from 1.91±0.00 to 3.96±0.00 mg/kg Zn; 0.15±0.00 to 0.17±0.00 mg/kg Pb; 0.20±0.00 to 1.98±0.00 mg/kg Cu; 0.03±0.00 to 0.27±0.00 mg/kg Cd; and 0.00±0.02 to 0.00±0.00 mg/kg Co; on average. The highest concentration of zinc and copper were found in the liver while manganese is also deposited more in the liver. The Analysis of Variance (ANOVA) test on the distribution and concentrations of all the metals in the liver, tissue and kidney shows that (p<0.05), i.e. there is significant difference in the amount of the elements in this samples and are not safe for human consumption.
Axial and Radial Variation of Fibre Characteristics of Bambusa vulgaris
Authors: Aderounmu A. F. , Adelusi E. A.
Published: September 2019

This study was carried out to investigate the axial and radial variations of fibre characteristics of Bambusa vulgaris. There were eighteen treatments for both axial and radial variations. The treatments were replicated three (3) times, in Complete Randomized Design (CRD). The experiment was carried out at the Wood Anatomy Laboratory of the Department of Forest Product Development and Utilization, Forestry Research Institute of Nigeria, Ibadan. Three samples (3) stands of B. vulgaris were randomly selected. Samples collected were cut into 10cm discs at 25%, 50% and 75% of the total height (axial positioning). The samples discs were partitioned into two zones which are core and peripheral (bark) layers. From each of the disc, 3 slivers were obtained both from radial and axial positions. Slivers obtained were macerated with an equal volume (1:1) of 10% glacial Acetic acid and 30% Hydrogen Peroxide (H2O2) at 100 ±2°C. The resulting image on light microscope screen was measured for fibre length, fibre diameter and lumen width.

At 50% sampling height and at outer layer, the highest fibre length of 3.25 mm, followed by 3.06 mm of bamboo sample stand 3 while the least 2.28 mm was recorded in sample stands 2 of 75% axial positioning and at peripheral layer. The lumen width ranged between 3.52 × 10-3 μm to 4.46 × 10-3 μm in the radial direction from the core to the peripheral (bark) of the bamboo. The result obtained for mean values of fiber diameter along the bamboo height ranged from 3.53 × 10-3 µm to 4.46 × 10-3 µm across the three (3) bamboo stands, sampling height and radial direction sampling respectively.

Among the fibre positioning, the fibre collected from 50% of the sampling height have higher fibre diameter, lumen width and fibre diameter at the peripheral region compare to the others.
Visualization of Dopant Oxygen Atoms in a Bi2Sr2CaCu2O8+δ Superconductor
Authors: Song Dongsheng , Zhang Xuefeng , Lian Chaosheng , Liu Hai , Alexandrou Ioannis , Lazić Ivan , Bosch Eric G. T. , Zhang Ding , Wang LiLi , Yu Rong , Cheng Zhiying , Song Canli , Ma Xucun , Duan Wenhui , Xue Qikun , Zhu Jing
Published: September 2019

A proper amount of excess oxygen plays a significant role in hole‐doped cuprate high‐Tc superconductivity. Here, the dopant oxygen in Bi2Sr2CaCu2O8+δ is directly imaged via integrated differential phase contrast combined with state‐of‐the‐art scanning transmission electron microscopy. The location of dopant oxygen is observed to be consistent with the position inferred from local strain analysis of the incommensurate structure. The influence of dopant oxygen on the local atomic lattice and electronic structure is further explored using first‐principle calculations. The dopant oxygen atoms not only aggravate the distortions of the local atomic arrangement but also alter the electronic states by transferring charge from the BiO planes to the CuO2 planes. The underlying mechanism of charge transfer is resolved. The results may also be applicable to other oxygen‐doped cuprates with high‐Tc superconductivity.
Distinctive Performance of Terahertz Photodetection Driven by Charge‐Density‐Wave Order in CVD‐Grown Tantalum Diselenide
Authors: Wang Lin , Wang Jin , Liu Changlong , Xu Huang , Li Ang , Wei Dacheng , Liu Yunqi , Chen Gang , Chen Xiaoshuang , Lu Wei
Published: September 2019

The quantum behavior of carriers in solid is the foundation of modern electronic and optoelectronic technology, but it is still facing huge challenges within inherited single‐particle quantum processes working at the millimeter wave/terahertz (THz) band. Here, a straightforward strategy for the direct detection of millimeter wave/THz photons in a sub‐wavelength metal‐TaSe2‐metal structure under strong interaction with a localized field of surface plasmon is proposed. By breaking the inversion symmetry under the perturbations of electric field and atomic reconstruction from van der Waals integration, the nonequilibrium electronic states under a radiant field can be manipulated in a collective fashion, leading to a large photocurrent responsivity over 40 A W−1 and noise equivalent power less than 1 pW Hz−1/2 even at room temperature. A more than 40‐fold enhancement in responsivity is achieved when transitioning from the normal phase to the CDW phase. The findings shed fresh light on the understanding of the delicate balance in the charge‐ordered phase, and facilitate the exploitation of a correlated electron system for optoelectronic applications in fields of security, remote sensing, and imaging.
π‐Conjugation Enables Ultra‐High Rate Capabilities and Cycling Stabilities in Phenothiazine Copolymers as Cathode‐Active Battery Materials
Authors: Acker Pascal , Rzesny Luisa , Marchiori Cleber F. N. , Araujo C. Moyses , Esser Birgit
Published: September 2019

In recent years, organic battery cathode materials have emerged as an attractive alternative to metal oxide–based cathodes. Organic redox polymers that can be reversibly oxidized are particularly promising. A drawback, however, often is their limited cycling stability and rate performance in a high voltage range of more than 3.4 V versus Li/Li+. Herein, a conjugated copolymer design with phenothiazine as a redox‐active group and a bithiophene co‐monomer is presented, enabling ultra‐high rate capability and cycling stability. After 30 000 cycles at a 100C rate, >97% of the initial capacity is retained. The composite electrodes feature defined discharge potentials at 3.6 V versus Li/Li+ due to the presence of separated phenothiazine redox centers. The semiconducting nature of the polymer allows for fast charge transport in the composite electrode at a high mass loading of 60 wt%. A comparison with three structurally related polymers demonstrates that changing the size, amount, or nature of the side groups leads to a reduced cell performance. This conjugated copolymer design can be used in the development of advanced redox polymers for batteries.
Oxide Catalysts with Ultrastrong Resistance to SO2 Deactivation for Removing Nitric Oxide at Low Temperature
Authors: Ma Zhaoxia , Sheng Liping , Wang Xinwei , Yuan Wentao , Chen Shiyuan , Xue Wei , Han Gaorong , Zhang Ze , Yang Hangsheng , Lu Yunhao , Wang Yong
Published: September 2019

Nitrogen oxides are one of the major sources of air pollution. To remove these pollutants originating from combustion of fossil fuels remains challenging in steel, cement, and glass industries as the catalysts are severely deactivated by SO2 during the low‐temperature selective catalytic reduction (SCR) process. Here, a MnOX/CeO2 nanorod catalyst with outstanding resistance to SO2 deactivation is reported, which is designed based on critical information obtained from in situ transmission electron microscopy (TEM) experiments under reaction conditions and theoretical calculations. The catalysts show almost no activity loss (apparent NOX reaction rate kept unchanged at 1800 µmol g−1 h−1) for 1000 h test at 523 K in the presence of 200 ppm SO2. This unprecedented performance is achieved by establishing a dynamic equilibrium between sulfates formation and decomposition over the CeO2 surface during the reactions and preventing the MnOX cluster from the steric hindrance induced by SO2, which minimized the deactivation of the active sites of MnOX/CeO2. This work presents the ultralong lifetime of catalysts in the presence of SO2, along with decent activity, marking a milestone in practical applications in low‐temperature selective catalytic reduction (SCR) of NOX.
In Situ Liquid Cell TEM Studies on Etching and Growth Mechanisms of Gold Nanoparticles at a Solid–Liquid–Gas Interface
Authors: Hutzler Andreas , Fritsch Birk , Jank Michael P. M. , Branscheid Robert , Martens R. Christian , Spiecker Erdmann , März Martin
Published: September 2019

Etching and growth of gold nanoparticles at a solid–liquid–gas interface are investigated via in situ liquid cell transmission electron microscopy. For this purpose, the gold precursor tetrachloroauric acid is enclosed in the wells of a free‐standing, locally thinned silicon nitride film covered by few‐layer graphene. Etching of gold is attributed to hydroxide radicals generated by radiolysis and gaseous species which are located within a gas bubble. The etching mechanism comprises two distinct cases. In one case, the gas bubble is in direct contact with the gold particle, separated only by a thin liquid membrane. In the other case, the gold particle is thoroughly immersed in liquid in the vicinity of the particle. In the latter, etching molecules diffuse from the bubble through the liquid toward the surface of the nanoparticle and subsequently etch the gold platelet. During the particle etching process, concurrent nucleation and ripening of gold nanoparticles are observed. This growth is induced by local supersaturation of the solution with gold ions. Experimental results show that the growth process is limited by diffusion, even though the diffusivity of reactants is very low due to narrow‐channel effects compared against the diffusivity of solvated ions in bulk liquids.
Robust Production of Well‐Controlled Microdroplets in a 3D‐Printed Chimney‐Shaped Milli‐Fluidic Device
Authors: Hwang Yoon‐Ho , Um Taewoong , Hong Jiwoo , Ahn Gwang‐Noh , Qiao Juan , Kang In Seok , Qi Li , Lee Hyomin , Kim Dong‐Pyo
Published: September 2019

3D‐printing technology has recently been exploited in droplet microfluidics due to its simplicity and low cost. Unresolved, however, is the design and fabrication of 3D‐printed droplet generators that allow high throughput production of monodisperse droplets with sizes ranging from tens to hundreds of microns in a robust manner. Herein, a newly designed 3D‐printed milli‐fluidic device with a chimney‐shaped void geometry that produces monodisperse droplets controllably with the size covering a broad range is reported. The droplet generator with four parallelized chimneys is devised to simultaneously generate droplets of various size as well as spherical glycine crystals of various size in a single system, demonstrating its potential as a point‐of‐care medicine manufacturing platform.
Large‐Area and Low‐Cost Nanoslit‐Based Flexible Metasurfaces for Multispectral Electromagnetic Wave Manipulation
Authors: Zhang Ming , Ma Xiaoliang , Pu Mingbo , Liu Kaipeng , Guo Yinghui , Huang Yijia , Xie Xin , Li Xiong , Yu Honglin , Luo Xiangang
Published: September 2019

Manipulating multispectral electromagnetic (EM) waves has drawn great attention due to its potential applications in EM compatibility, radiative cooling, and multispectral imaging. Metasurfaces are intensively investigated to control EM waves and achieve versatile functions. However, the design of multispectral manipulation and the fabrication of multiscale metasurfaces remain a great challenge. Here, a multiscale flexible metasurface with nanometer‐sized characteristic dimensions and a square centimeter sized area is designed and fabricated for the simultaneous manipulation of infrared and terahertz waves. A simple yet powerful analytic method derived from catenary field theory is proposed to guide the design. A metasurface consisting of 2D nanoslit array is fabricated onto a flexible polyimide substrate by combining shadow mask fabrication with surface plasmon lithography to achieve nanoscale, large‐area, and repeatable fabrication. The experimental results show that the proposed metasurface possesses high reflectance exceeding 95% within the 8–12 µm wavelength range, indicating low thermal emissivity. Additionally, the metasurface exhibits low reflection in the THz regime and is capable of implementing integrated functions in conjunction with THz devices. Furthermore, the significant advantage of flexibility affords the metasurface excellent compatibility with irregular surfaces. This work may provide important guidance for the design and fabrication of large‐scale multispectral metasurfaces.
Degradation Mechanisms in Organic Lead Halide Perovskite Light‐Emitting Diodes
Authors: Prakasam Vittal , Tordera Daniel , Bolink Henk J. , Gelinck Gerwin
Published: September 2019

Organic–inorganic metal halide perovskites have attracted significant attention for low‐cost, high‐efficiency, color‐pure light‐emitting applications. However, as seen in many reports so‐far, perovskite light‐emitting diodes (PeLED) suffer from poor operational lifetime, limiting their practical use. The underlying degradation mechanism is a topic of crucial importance. Here, the degradation mechanisms of methylammonium lead bromide based PeLED are investigated. When the PeLED is electrically biased, there is an initial raise in the luminance followed by a rapid reduction in luminance and current density. Microscopic studies reveal the formation of micrometer‐sized spots that are photoluminescent but not electroluminescent. It is demonstrated that this degradation is due to the formation of gaseous compounds that leads to local delamination of the cathode, thereby reducing the electroluminescence. When the degraded cathode is substituted with a fresh cathode, the initial luminance is largely recovered. By further analyzing the buried interface of the cathode, the formation of lead bromide and gaseous methylamine due to the degradation of the perovskite layer are revealed. These insights will help to further improve the lifetime of PeLEDs. As an example, it is shown that substituting methylammonium cations by cesium leads to longer lifetimes.
Flexible Luminescent Organic Bulk Crystal: 2D Elasticity toward 3D Optical Waveguide
Authors: Huang Rui , Tang Baolei , Ye Kaiqi , Wang Chenguang , Zhang Hongyu
Published: September 2019

The study of elastic organic single crystals becomes a hot research field in the crystal engineering, and elastic bending of needle‐like crystals has been carefully investigated recently. Herein, based on a structurally simple molecule dimethyl 2,5‐diaminoterephthalate (DMDAT), the organic crystals which display not only elastic bending ability but also elastic twisting ability under applied stress are reported. These ribbon‐like DMDAT crystals are fully flexible and can be freely bended and twisted, thus forming any 3D conformation. Moreover, the unique X‐shaped tetrasubstituted benzene structure enables DMDAT crystals to display efficient yellow emission based on a very small π‐system. Taking these advantages, 3D optical waveguide is successfully realized in the DMDAT crystal with a highly twisted 3D belt‐shaped structure, demonstrating the ultimate 3D application of flexible organic bulk crystals.
Accelerated Search for BaTiO3‐Based Ceramics with Large Energy Storage at Low Fields Using Machine Learning and Experimental Design
Authors: Yuan Ruihao , Tian Yuan , Xue Dezhen , Xue Deqing , Zhou Yumei , Ding Xiangdong , Sun Jun , Lookman Turab
Published: September 2019

The problem that is considered is that of maximizing the energy storage density of Pb‐free BaTiO3‐based dielectrics at low electric fields. It is demonstrated that how varying the size of the combinatorial search space influences the efficiency of material discovery by comparing the performance of two machine learning based approaches where different levels of physical insights are involved. It is started with physics intuition to provide guiding principles to find better performers lying in the crossover region in the composition–temperature phase diagram between the ferroelectric phase and relaxor ferroelectric phase. Such an approach is limiting for multidopant solid solutions and motivates the use of two data‐driven machine learning and design strategies with a feedback loop to experiments. Strategy I considers learning and property prediction on all the compounds, and strategy II learns to preselect compounds in the crossover region on which prediction is carried out. By performing only two active learning loops via strategy II, the compound (Ba0.86Ca0.14)(Ti0.79Zr0.11Hf0.10)O3 is synthesized with the largest energy storage density ≈73 mJ cm−3 at a field of 20 kV cm−1, and an insight into the relative performance of the strategies using varying levels of knowledge is provided.
Enhanced Near‐Infrared Photoresponse of Inverted Perovskite Solar Cells Through Rational Design of Bulk‐Heterojunction Electron‐Transporting Layers
Authors: Chen Chih‐I , Wu Shengfan , Lu Yen‐An , Lee Chia‐Chen , Ho Kuo‐Chuan , Zhu Zonglong , Chen Wen‐Chang , Chueh Chu‐Chen
Published: September 2019

How to extend the photoresponse of perovskite solar cells (PVSCs) to the region of near‐infrared (NIR)/infrared light has become an appealing research subject in this field since it can better harness the solar irradiation. Herein, the typical fullerene electron‐transporting layer (ETL) of an inverted PVSC is systematically engineered to enhance device's NIR photoresponse. A low bandgap nonfullerene acceptor (NFA) is incorporated into the fullerene ETL aiming to intercept the NIR light passing through the device. However, despite forming type II charge transfer with fullerene, the blended NFA cannot enhance the device's NIR photoresponse, as limited by the poor dissociation of photoexciton induced by NIR light. Fortunately, it can be addressed by adding a p‐type polymer. The ternary bulk‐heterojunction (BHJ) ETL is demonstrated to effectively enhance the device's NIR photoresponse due to the better cascade‐energy‐level alignment and increased hole mobility. By further optimizing the morphology of such a BHJ ETL, the derived PVSC is finally demonstrated to possess a 40% external quantum efficiency at 800 nm with photoresponse extended to the NIR region (to 950 nm), contributing ≈9% of the overall photocurrent. This study unveils an effective and simple approach for enhancing the NIR photoresponse of inverted PVSCs.
Generation and Propagation of Optical Superoscillatory Vortex Arrays
Authors: Lin Haolin , Fu Shenhe , Deng Zhigui , Zhou Haiqiong , Yin Hao , Li Zhen , Chen Zhenqiang
Published: September 2019

Superoscillation is an intriguing wave phenomenon which enables subwavelength features propagating into far field and hence has potential applications in super‐resolution microscopy as well as particle trapping and manipulation. While previous demonstrations mostly concentrate on designing complicated nanostructures for generating uncontrollable superoscillatory functions, here a new technique which allows for creating polynomially shaped superoscillatory functions that contain phase singularity arrays is demonstrated both theoretically and experimentally. Such a technique is implemented in optical experiments for the first time and controllable superoscillatory lobes with feature much below the diffraction limit is achieved. More importantly, a general theoretical framework, which, to our knowledge, has not been reported before, is developed to show how the created superoscillations propagate to a distance of many Rayleigh ranges and eventually disappear when the distance is sufficiently larger. The validity of the model is confirmed by the experiments. The results may trigger further studies in light field shaping and manipulations in subwavelength scale.
Cavity‐Photon‐Induced High‐Order Transitions between Ground States of Quantum Dots
Authors: Gudmundsson Vidar , Abdullah Nzar Rauf , Tang Chi‐Shung , Manolescu Andrei , Moldoveanu Valeriu
Published: September 2019

It is shown that quantum electromagnetic transitions to high orders are essential to describe the time‐dependent path of a nanoscale electron system in a Coulomb blockade regime when coupled to external leads and placed in a 3D rectangular photon cavity. The electronic system consists of two quantum dots embedded asymmetrically in a short quantum wire. The two lowest in energy spin degenerate electron states are mostly localized in each dot with only a tiny probability in the other dot. In the presence of the leads, a slow high‐order transition between the ground states of the two quantum dots is identified. The Fourier power spectrum for photon–photon correlations in the steady state shows a Fano type of resonance for the frequency of the slow transition. Full account is taken of the geometry of the multilevel electronic system, and the electron–electron Coulomb interactions together with the para‐ and diamagnetic electron–photon interactions are treated with step‐wise exact numerical diagonalization and truncation of appropriate many‐body Fock spaces. The matrix elements for all interactions are computed analytically or numerically exactly.
Photo‐induced and Rapid Labeling of Tetrazine‐Bearing Proteins via Cyclopropenone‐Caged Bicyclononynes
Authors: Mayer Susanne V. , Murnauer Anton , von Wrisberg Marie‐Kristin , Jokisch Marie‐Lena , Lang Kathrin
Published: September 2019

Inverse electron‐demand Diels–Alder cycloadditions (iEDDAC) between tetrazines and strained alkenes/alkynes have emerged as essential tools for studying and manipulating biomolecules. A light‐triggered version of iEDDAC (photo‐iEDDAC) is presented that confers spatio‐temporal control to bioorthogonal labeling in vitro and in cellulo. A cyclopropenone‐caged dibenzoannulated bicyclo[6.1.0]nonyne probe (photo‐DMBO) was designed that is unreactive towards tetrazines before light‐activation, but engages in iEDDAC after irradiation at 365 nm. Aminoacyl tRNA synthetase/tRNA pairs were discovered for efficient site‐specific incorporation of tetrazine‐containing amino acids into proteins in living cells. In situ light activation of photo‐DMBO conjugates allows labeling of tetrazine‐modified proteins in living E. coli. This allows proteins in living cells to be modified in a spatio‐temporally controlled manner and may be extended to photo‐induced and site‐specific protein labeling in animals.
Bioinspired Synergistic Fluorescence‐Color‐Switchable Polymeric Hydrogel Actuators
Authors: Wei Shuxin , Lu Wei , Le Xiaoxia , Ma Chunxin , Lin Han , Wu Baoyi , Zhang Jiawei , Theato Patrick , Chen Tao
Published: September 2019

Many living organisms have amazing control over their color, shape, and morphology for camouflage, communication, and even reproduction in response to interplay between environmental stimuli. Such interesting phenomena inspire scientists to develop smart soft actuators/robotics via integrating color‐changing functionality based on polymer films or elastomers. However, there has been no significant progress in synergistic color‐changing and shape‐morphing capabilities of life‐like material systems such as hydrogels. Herein, we reported a new class of bioinspired synergistic fluorescence‐color‐switchable polymeric hydrogel actuators based on supramolecular dynamic metal–ligand coordination. Artificial hydrogel apricot flowers and chameleons have been fabricated for the first time, in which simultaneous color‐changing and shape‐morphing behaviors are controlled by the subtle interplay between acidity/alkalinity, metal ions, and temperature. This work has made color‐changeable soft machines accessible and is expected to hold wide potential applications in biomimetic soft robotics, biological sensors, and camouflage.
Charge‐Shift Bonding: A New and Unique Form of Bonding
Authors: Shaik Sason , Danovich David , Galbraith John Morrison , Braïda Benoît , Wu Wei , Hiberty Philippe C.
Published: September 2019

Charge‐shift bonds (CSBs) constitute a new class of bonds different than covalent/polar‐covalent and ionic bonds. Bonding in CSBs does not arise from either the covalent or the ionic structures of the bond, but rather from the resonance interaction between the structures. This Essay describes the reasons why the CSB family was overlooked by valence‐bond pioneers and then demonstrates that the unique status of CSBs is not theory‐dependent. Thus, valence bond (VB), molecular orbital (MO), and energy decomposition analysis (EDA), as well as a variety of electron density theories all show the distinction of CSBs vis‐à‐vis covalent and ionic bonds. Furthermore, the covalent–ionic resonance energy can be quantified from experiment, and hence has the same essential status as resonance energies of organic molecules, e.g., benzene. The Essay ends by arguing that CSBs are a distinct family of bonding, with a potential to bring about a Renaissance in the mental map of the chemical bond, and to contribute to productive chemical diversity.
Designed Negative Feedback from Transiently Formed Catalytic Nanostructures
Authors: Afrose Syed Pavel , Bal Subhajit , Chatterjee Ayan , Das Krishnendu , Das Dibyendu
Published: September 2019

Highly dynamic and complex systems of microtubules undergo a substrate‐induced change of conformation that leads to polymerization. Owing to the augmented catalytic potential at the polymerized state, rapid hydrolysis of the substrate is observed, leading to catastrophe, thus realizing the out‐of‐equilibrium state. A simple synthetic mimic of these dynamic natural systems is presented, where similar substrate induced conformational change is observed and a transient helical morphology is accessed. Further, augmented catalytic potential of these helical nanostructures leads to rapid hydrolysis of the substrate providing negative feedback on the stability of the nanostructures and realization of an out‐of‐equilibrium state. This simple system, made from amino acid functionalized lipids, demonstrates a substrate‐induced self‐assembled state, where the fuel‐to‐waste conversion leads to the temporal presence of helical nanostructures.
Programmable Exposure of Pt Active Facets for Efficient Oxygen Reduction
Authors: Wang Guanzhi , Yang Zhenzhong , Du Yingge , Yang Yang
Published: September 2019

To produce efficient ORR catalysts with low Pt content, PtNi porous films (PFs) with sufficiently exposed Pt active sites were designed by an approach combining electrochemical bottom‐up (electrodeposition) and top‐down (anodization) processes. The dynamic oxygen‐bubble template (DOBT) programmably controlled by a square‐wave potential was used to tune the catalyst morphology and expose Pt active facets in PtNi PFs. Surface‐bounded species, such as hydroxyl (OH*, *=surface site) on the exposed PtNi PFs surfaces were adjusted by the applied anodic voltage, further affecting the dynamic oxygen (O2) bubbles adsorption on Pt. As a result, PtNi PF with enriched Pt(111) facets (denoted as Pt3.5 %Ni PF) was obtained, showing prominent ORR activity with an onset potential of 0.92 V (vs. RHE) at an ultra‐low Pt loading (0.015 mg cm−2).
Diverse Nanoassemblies of Graphene Quantum Dots and Their Mineralogical Counterparts
Authors: Qu Zhi‐bei , Feng Wei‐Jie , Wang Yichun , Romanenko Fedor , Kotov Nicholas A.
Published: September 2019

Complex structures from nanoparticles are found in rocks, soils, and sea sediments but the mechanisms of their formation are poorly understood, which causes controversial conclusions about their genesis. Here we show that graphene quantum dots (GQDs) can assemble into complex structures driven by coordination interactions with metal ions commonly present in environment and serve a special role in Earth's history, such as Fe3+ and Al3+. GQDs self‐assemble into mesoscale chains, sheets, supraparticles, nanoshells, and nanostars. Specific assembly patterns are determined by the effective symmetry of the GQDs when forming the coordination assemblies with the metal ions. As such, maximization of the electronic delocalization of π‐orbitals of GQDs with Fe3+ leads to GQD‐Fe‐GQD units with D2 symmetry, dipolar bonding potential, and linear assemblies. Taking advantage of high electron microscopy contrast of carbonaceous nanostructures in respect to ceramic background, the mineralogical counterparts of GQD assemblies are found in mineraloid shungite. These findings provide insight into nanoparticle dynamics during the rock formation that can lead to mineralized structures of unexpectedly high complexity.
Performance of erythorbic acid as an oxygen scavenger in salted fresh and degraded monoethylene glycol under a magnetic memory effect
Authors: Al Helal Ammar , Iglauer Stefan , Gubner Rolf , Barifcani Ahmed
Published: September 2019

Studies show that erythorbic acid is an effective oxygen scavenger in the food industry, thereby suggesting its potential for use in monoethylene glycol (MEG) regeneration systems. However, its performance under magnetic memory effects has not been studied. This study was conducted with 85‐vol.% fresh MEG (F‐MEG) and degraded MEG (D‐MEG) solutions, preadjusted to pH 9.0 and pretreated with a magnetic field (MF). Two oxygen concentrations, ~7,000 and ~1,000 ppb, high‐salinity concentrations (HF‐MEG and HD‐MEG), and organic acids were also employed. The applied MF strength, generated by a cylindrical permanent magnet, was ~0.65 T.

The erythorbic acid scavenging performance was enhanced upon exposure of the HF‐MEG solutions to an MF. Conversely, the magnetized salt‐free D‐MEG solutions displayed a lower scavenging performance than the nonmagnetized solutions: Oxygen removal was more effective in the D‐MEG solutions than in the HF‐MEG solutions, regardless of magnetization, due to formic acid formation during the thermal oxidization process. Furthermore, the magnetized HF‐MEG solutions exhibited a progressive increase in pH over time, whereas the nonexposed and D‐MEG solutions presented different responses. Iron ions, acting as metal catalysts, also affected the oxygen scavenging performance in the D‐MEG tests. The results suggest that the erythorbic acid scavenging performance can be improved by promoting the forward reaction using an MF. In addition, in the presence of erythorbic acid and only under specific conditions, formic acid can be used as secondary oxygen scavenger in oil and gas industry. Stable alkaline conditions are also necessary to achieve better scavenging performance. These results can be attributed to the influence of the MF on the spin state mechanism, given that the electron spin dynamics are affected by the Zeeman effect.
Electropermeabilization of metastatic chondrosarcoma cells from primary cell culture
Authors: Michel Olga , Błasiak Piotr , Saczko Jolanta , Kulbacka Julita , Drąg‐Zalesińska Małgorzata , Rzechonek Adam
Published: September 2019

Primary cell cultures are challenging, but reliable model reflecting tumor response in vitro. The study was designed to examine if the increased electropermeabilization can overcame initial drug insensitivity in chondrosarcoma cells from lung metastasis. We established a primary cell culture and evaluated the cytotoxic impact of four drugs—cisplatin (CDDP), camptothecin, 2‐methoxyestradiol, and leucovorin calcium (LeuCa). After determination of parameters allowing for electropermeabilization, we performed electrochemotherapy in vitro with the least toxic drugs—CDDP and LeuCa. Although combining CDDP and leucovorin together increased their toxicity and supported apoptosis, application of pulsed electric fields (PEFs) brought no advantage for their efficacy. The study emphasizes the need for introduction of primary cell cultures into studies on pulse electric fields as model frequently less sensitive to PEF‐based treatments than continuous cell lines.