bluuebunny/crossref_metadata_2025 huggingface dataset:
Optically and radio frequency (RF) transparent meta-glass
Authors: Safari Mahdi , He Yuchu , Kim Minseok , Kherani Nazir P. , Eleftheriades George V.
Published: June 2020

We propose a radio frequency (RF) and visibly transparent composite metasurface design comprising newly developed transparent multilayer conductive coatings. Detailed experimental and theoretical analysis of the RF/visible transparency of the proposed meta-glass is provided. The proposed nature-inspired symmetrical honeycomb-shaped meta-glass design, alters the electromagnetic properties of the glass substrate in the RF spectrum by utilizing visibly transparent Ag-based conductive coatings on each side. Furthermore, the competing effect of the Ag thickness on optical and RF transparency is discussed. We show that using multilayer dielectric-metal coatings, specifically 5-layered spectrally selective coatings, RF transparency of the meta-glass can be enhanced while preserving visible transparency. Herein we demonstrate high transparency meta-glass with 83% and 78% peak RF and optical transmission at 28 GHz and 550 nm, respectively. The meta-glass yields enhanced RF transmission by 80% and 10% when compared to low-emissivity glass and bare glass, respectively. The meta-glass design presented here is amenable to a variety of 5G applications including automobile radar systems. This work provides a superior alternative to the standard indium-tin-oxide (ITO) transparent material which is becoming scarce. Moreover, this study paves the way for the design of new visibly transparent metamaterials and artificial dielectrics.
Broadband photonic topological insulator based on triangular-holes array with higher energy filling efficiency
Authors: Zhang Zhishen , Li Feng , Lu Jiuyang , Liu Tao , Heng Xiaobo , He Yongcheng , Liang Haohua , Gan Jiulin , Yang Zhongmin
Published: June 2020

Photonic topological insulators (PTIs) bring markedly new opportunities to photonic devices with low dissipation and directional transmission of signal over a wide wavelength range due to the broadband topological protection. However, the maximum gap/mid-gap ratio of PTIs is below 10% and hardly further improved duo to the lack of new bandwidth enhancement mechanism. In this paper, a PTI with the gap/mid-gap ratio of 16.25% is proposed. The designed PTI has a honeycomb lattice structure with triangular air holes, and such a wide bandwidth is obtained by optimizing the refractive-index profile of the primitive cell for increasing the energy proportion in the geometric perturbation region. The PTI shows a large topological nontrivial gap (the gap/mid-gap ratio 33.4%) with the bandwidth approaching its theoretical limit. The edge states propagate smoothly around sharp bends within 1430–1683 nm. Due to topological protection, the bandwidth only decreases 1.38% to 1450–1683 nm under 1%-random-bias disorders. The proposed PTI has a potential application in future high-capacity and nonlinear topological photonic devices.
Pixeled metasurface for multiwavelength detection of vitamin D
Authors: Di Meo Valentina , Crescitelli Alessio , Moccia Massimo , Sandomenico Annamaria , Cusano Angela M. , Portaccio Marianna , Lepore Maria , Galdi Vincenzo , Esposito Emanuela
Published: June 2020

The steadily increasing demand for accurate analysis of vitamin D level,viameasurement of its best general marker, 25-hydroxyvitamin D (25(OH)D), pushes for the development of novel automated assays capable of working at very low concentrations. Here, we propose a plasmonic biosensor of 25(OH)D3 (calcifediol) based on surface-enhanced infrared absorption spectroscopy, which exploits the resonant coupling between plasmonic nanoantennas and vibrational excitation of small molecules. Specifically, our proposed platform features a large-area (several mm2) metasurface made of gold nanoantennas fabricated on a silicon substrate, comprising different macroregions (“pixels”) of area 500 × 500 µm2. In each pixel, the nanoantenna geometrical parameters are tuned so as to support localized surface plasmon resonances (and hence large field enhancements at the nanoscale) within different regions of the infrared spectrum. As a result, a single chip is capable of performing analysis from the region of functional groups to that of fingerprint. Two different designs are fabricatedviaelectron beam lithography, functionalized with a correlated antibody for the detection of 25(OH)D3, and characterizedviaFourier-transform infrared spectroscopy. Our experiments demonstrate the capability to detect a concentration as low as 86 pmol/L, and an amount of immobilized small molecules of 25(OH)D3 monohydrate (molecular weight: 418.65 g/mol) as low as 4.31 amol over an area of 100 × 100 µm2.
Plasmonic nanostructures in photodetection, energy conversion and beyond
Authors: Lin Keng-Te , Lin Han , Jia Baohua
Published: June 2020

This review article aims to provide a comprehensive understanding of plasmonic nanostructures and their applications, especially on the integration of plasmonic nanostructures into devices. Over the past decades, plasmonic nanostructures and their applications have been intensively studied because of their outstanding features at the nanoscale. The fundamental characteristics of plasmonic nanostructures, in particular, the electric field enhancement, the generation of hot electrons, and thermoplasmonic effects, play essential roles in most of the practical applications. In general, these three main characteristics of plasmonic nanostructures occur concomitantly when electromagnetic waves interact with plasmonic nanostructures. However, comprehensive review investigating these three main effects of plasmonic nanostructures simultaneously remains elusive. In this article, the fundamental characteristics of plasmonic nanostructures are discussed, especially the interactions between electromagnetic waves and plasmonic nanostructures that lead to the change in near-field electric fields, the conversion of photon energy into hot electrons through plasmon decay, and the photothermal effects at the nanoscale. The applications, challenges faced in these three areas and the future trends are also discussed. This article will provide guidance towards integration of plasmonic nanostructures for functional devices for both academic researchers and engineers in the fields of silicon photonics, photodetection, sensing, and energy harvesting.
Phase-controlled metasurface design via optimized genetic algorithm
Authors: Fan Yulong , Xu Yunkun , Qiu Meng , Jin Wei , Zhang Lei , Lam Edmund Y. , Tsai Din Ping , Lei Dangyuan
Published: June 2020

In an optical Pancharatnam-Berry (PB) phase metasurface, each sub-wavelength dielectric structure of varied spatial orientation can be treated as a point source with the same amplitude yet varied relative phase. In this work, we introduce an optimized genetic algorithm (GA) method for the synthesis of one-dimensional (1D) PB phase-controlled dielectric metasurfaces by seeking for optimized phase profile solutions, which differs from previously reported amplitude-controlled GA method only applicable to generate transverse optical modes with plasmonic metasurfaces. The GA–optimized phase profiles can be readily used to construct dielectric metasurfaces with improved functionalities. The loop of phase-controlled GA consists of initialization, random mutation, screened evolution, and duplication. Here random mutation is realized by changing the phase of each unit cell, and this process should be efficient to obtain enough mutations to drive the whole GA process under supervision of appropriate mutation boundary. A well-chosen fitness function ensures the right direction of screened evolution, and the duplication process guarantees an equilibrated number of generated light patterns. Importantly, we optimize the GA loop by introducing a multi-step hierarchical mutation process to break local optimum limits. We demonstrate the validity of our optimized GA method by generating longitudinal optical modes (i. e., non-diffractive light sheets) with 1D PB phase dielectric metasurfaces having non-analytical counter-intuitive phase profiles. The produced large-area, long-distance light sheets could be used for realizing high-speed, low-noise light-sheet microscopy. Additionally, a simplified 3D light pattern generated by a 2D PB phase metasurface further reveals the potential of our optimized GA method for manipulating truly 3D light fields.
Boolean learning under noise-perturbations in hardware neural networks
Authors: Andreoli Louis , Porte Xavier , Chrétien Stéphane , Jacquot Maxime , Larger Laurent , Brunner Daniel
Published: June 2020

A high efficiency hardware integration of neural networks benefits from realizing nonlinearity, network connectivity and learning fully in a physical substrate. Multiple systems have recently implemented some or all of these operations, yet the focus was placed on addressing technological challenges. Fundamental questions regarding learning in hardware neural networks remain largely unexplored. Noise in particular is unavoidable in such architectures, and here we experimentally and theoretically investigate its interaction with a learning algorithm using an opto-electronic recurrent neural network. We find that noise strongly modifies the system’s path during convergence, and surprisingly fully decorrelates the final readout weight matrices. This highlights the importance of understanding architecture, noise and learning algorithm as interacting players, and therefore identifies the need for mathematical tools for noisy, analogue system optimization.
Superconducting nanowire single-photon detectors for quantum information
Authors: You Lixing
Published: June 2020

The superconducting nanowire single-photon detector (SNSPD) is a quantum-limit superconducting optical detector based on the Cooper-pair breaking effect by a single photon, which exhibits a higher detection efficiency, lower dark count rate, higher counting rate, and lower timing jitter when compared with those exhibited by its counterparts. SNSPDs have been extensively applied in quantum information processing, including quantum key distribution and optical quantum computation. In this review, we present the requirements of single-photon detectors from quantum information, as well as the principle, key metrics, latest performance issues, and other issues associated with SNSPD. The representative applications of SNSPDs with respect to quantum information will also be covered.
Predictive and generative machine learning models for photonic crystals
Authors: Christensen Thomas , Loh Charlotte , Picek Stjepan , Jakobović Domagoj , Jing Li , Fisher Sophie , Ceperic Vladimir , Joannopoulos John D. , Soljačić Marin
Published: June 2020

The prediction and design of photonic features have traditionally been guided by theory-driven computational methods, spanning a wide range of direct solvers and optimization techniques. Motivated by enormous advances in the field of machine learning, there has recently been a growing interest in developing complementary data-driven methods for photonics. Here, we demonstrate several predictive and generative data-driven approaches for the characterization and inverse design of photonic crystals. Concretely, we built a data set of 20,000 two-dimensional photonic crystal unit cells and their associated band structures, enabling the training of supervised learning models. Using these data set, we demonstrate a high-accuracy convolutional neural network for band structure prediction, with orders-of-magnitude speedup compared to conventional theory-driven solvers. Separately, we demonstrate an approach to high-throughput inverse design of photonic crystals via generative adversarial networks, with the design goal of substantial transverse-magnetic band gaps. Our work highlights photonic crystals as a natural application domain and test bed for the development of data-driven tools in photonics and the natural sciences.
Perovskite nanowire lasers on low-refractive-index conductive substrate for high-Q and low-threshold operation
Authors: Markina Daria I. , Pushkarev Anatoly P. , Shishkin Ivan I. , Komissarenko Filipp E. , Berestennikov Alexander S. , Pavluchenko Alexey S. , Smirnova Irina P. , Markov Lev K. , Vengris Mikas , Zakhidov Anvar A. , Makarov Sergey V.
Published: June 2020

Over the last five years, inorganic lead halide perovskite nanowires have emerged as prospective candidates to supersede standard semiconductor analogs in advanced photonic designs and optoelectronic devices. In particular, CsPbX3 (X = Cl, Br, I) perovskite materials have great advantages over conventional semiconductors such as defect tolerance, highly efficient luminescence, and the ability to form regularly shaped nano- and microcavities from solution via fast crystallization. However, on the way of electrically pumped lasing, the perovskite nanowires grown on transparent conductive substrates usually suffer from strong undesirable light leakage increasing their threshold of lasing. Here, we report on the integration of CsPbBr3 nanowires with nanostructured indium tin oxide substrates possessing near-unity effective refractive index and high conductivity by using a simple wet chemical approach. Surface passivation of the substrates is found out to govern the regularity of the perovskite resonators’ shape. The nanowires show room-temperature lasing with ultrahigh quality factors (up to 7860) which are up to four times higher than that of similar structures on a flat indium tin oxide layer, resulting in more than twofold reduction of the lasing threshold for the nanostructured substrate. Numerical modeling of eigenmodes of the nanowires confirms the key role of low-refractive-index substrate for improved light confinement in the Fabry–Pérot cavity which results in superior laser performance.
All-dielectric metasurfaces for polarization manipulation: principles and emerging applications
Authors: Hu Yueqiang , Wang Xudong , Luo Xuhao , Ou Xiangnian , Li Ling , Chen Yiqin , Ping Yang  , Wang Shuai , Duan Huigao
Published: June 2020

Metasurfaces, composed of specifically designed subwavelength units in a two-dimensional plane, offer a new paradigm to design ultracompact optical elements that show great potentials for miniaturizing optical systems. In the past few decades, metasurfaces have drawn broad interests in multidisciplinary communities owing to their capability of manipulating various parameters of the light wave with plentiful functionalities. Among them, pixelated polarization manipulation in the subwavelength scale is a distinguished ability of metasurfaces compared to traditional optical components. However, the inherent ohmic loss of plasmonic-type metasurfaces severely hinders their broad applications due to the low efficiency. Therefore, metasurfaces composed of high-refractive-index all-dielectric antennas have been proposed to achieve high-efficiency devices. Moreover, anisotropic dielectric nanostructures have been shown to support large refractive index contrast between orthogonal polarizations of light and thus provide an ideal platform for polarization manipulation. Herein, we present a review of recent progress on all-dielectric metasurfaces for polarization manipulation, including principles and emerging applications. We believe that high efficient all-dielectric metasurfaces with the unprecedented capability of the polarization control can be widely applied in areas of polarization detection and imaging, data encryption, display, optical communication and quantum optics to realize ultracompact and miniaturized optical systems.
Nanoscale control of single molecule Förster resonance energy transfer by a scanning photonic nanoantenna
Authors: Sanz-Paz Maria , Wenger Jerome , van Hulst Niek F. , Mivelle Mathieu , Garcia-Parajo Maria F.
Published: June 2020

Förster Resonance Energy Transfer (FRET) is a widely applied technique in biology to accurately measure intra- and inter-molecular interactions at the nanometre scale. FRET is based on near-field energy transfer from an excited donor to a ground state acceptor emitter. Photonic nanoantennas have been shown to modify the rate, efficiency and extent of FRET, a process that is highly dependent on the near-field gradient of the antenna field as felt by the emitters, and thus, on their relative distance. However, most of the experiments reported to date focus on fixed antennas where the emitters are either immobilized or diffusing in solution, so that the distance between the antenna and the emitters cannot be manipulated. Here, we use scanning photonic nanoantenna probes to directly modulate the FRET efficiency between individual FRET pairs with an unprecedented nanometric lateral precision of 2 nm on the antenna position. We find that the antenna acts as an independent acceptor element, competing with the FRET pair acceptor. We directly map the competition between FRET and donor-antenna transfer as a function of the relative position between the antenna and the FRET donor-acceptor pair. The experimental data are well-described by FDTD simulations, confirming that the modulation of FRET efficiency is due to the spatially dependent coupling of the single FRET pair to the photonic antenna.
Terahertz plasmonic phase-jump manipulator for liquid sensing
Authors: Huang Yi , Zhong Shuncong , Shi Tingting , Shen Yao-chun , Cui Daxiang
Published: June 2020

Terahertz (THz) plasmonic sensors has been regarded as exciting advances in biomedical engineering, due to their real-time, label-free, and ultrasensitive monitoring features. But actually, its widespread application remains impeded by poor modulation properties of operating frequency, single amplitude characterization method, and limited to low-loss substances. In the work, an ultraprecision THz sensor is achieved with direct phase readout capacity via combining steerable plasmonic resonance and attenuated total reflection. Interestingly, the oft-neglected THz phase were found to be ideal for plasmonic sensing characterization. Detailed investigation shows that the reflected THz phase exhibits two entirely different jump responses to coupling gap. Remarkably, the Q-factor of phase spectra for optimal coupling gaps, are generally higher than that of fixed coupling gaps, which falls within the range of 9.7–43.4 (4–26 times higher than its counterpart in amplitude measurements) in liquids sensing. The unique phase-jump responses on metasurfaces pave the way for novel THz sensing methods.
Resisted Sled Training for Young Athletes: When to Push and Pull
Authors: Cahill Micheál J. , Cronin John B. , Oliver Jon L. , Clark Kenneth P. , Lloyd Rhodri S. , Cross Matt R.
Published: June 2020

There is a renewed interest is resisted sled training (RST); however, little uniformity exists regarding the integration of best practices in RST for young athletes. This article reviews the prescription of load, methods of RST, and the integration of sprint-specific periodized training blocks during the preparatory phase to elicit the greatest gains within different phases of sprint performance such as early acceleration, late acceleration, and the transition to maximum velocity. A targeted, long-term approach to RST may enable more effective development of speed in young athletes.
Physical Characteristics and the Talent Identification and Development Processes in Male Youth Soccer: A Narrative Review
Authors: Kelly Adam L. , Williams Craig A.
Published: June 2020

Talent identification and development in male youth soccer are complex and multidimensional processes. The English Football Association “4 Corner Model” is often adopted by academies to support coaches and practitioners to implement a multidisciplinary approach to their talent identification and development framework. This holistic approach is characterized by technical/tactical, psychological, social, and physical attributes, which are central to academy recruitment and individual long-term athlete development. The aim of this narrative review is to provide a critical synthesis of the physical characteristics within this model, which facilitate talent identification and development, namely physical performance, growth and maturation, and the relative age effect.
Enseigner l’entrepreneuriat autrement : l’approche du Startup Weekend
Authors: Delisle Julie
Published: June 2020

Alors qu’il est de plus en plus clair que l’enseignement de l’entrepreneuriat gagne à se faire à l’aide de méthodes de pédagogie actives, des initiatives comme les Startup Weekends sont en pleine expansion à travers le monde. Cet article vise à étudier ce phénomène afin de tirer des pistes pour l’enseignement de l’entrepreneuriat, mais également à réfléchir sur certains de ses effets, comme la valorisation du surtravail et de la vitesse en startups.
The generalized centrally extended Lie algebraic structures and related integrable heavenly type equations
Authors: Hentosh O.Ye. , Balinsky A.A. , Prykarpatski A.K.
Published: June 2020

There are studied Lie-algebraic structures of a wide class of heavenly type non-linear integrable equations, related with coadjoint flows on the adjoint space to a loop vector field Lie algebra on the torus. These flows are generated by the loop Lie algebras of vector fields on a torus and their coadjoint orbits and give rise to the compatible Lax-Sato type vector field relationships. The related infinite hierarchy of conservations laws is analysed and its analytical structure, connected with the Casimir invariants, is discussed. We present the typical examples of such equations and demonstrate in details their integrability within the scheme developed. As examples, we found and described new multidimensional generalizations of the Mikhalev-Pavlov and Alonso-Shabat type integrable dispersionless equation, whose seed elements possess a special factorized structure, allowing to extend them to the multidimensional case of arbitrary dimension.
Nietzsche sobrevolando Iberoamérica
Authors: Sánchez Lopera Alejandro
Published: June 2020

Los desencuentros de la filosofía latinoamericana con Nietzsche pueden entenderse como un síntoma de algo más que un problema de legibilidad o malentendido. En tanto pensamiento de lo uno, la filosofía latinoamericana (mayoritaria) no puede servirse del pensamiento nietzscheano: es imposible construir un pensamiento del origen y la unidad desde un pensamiento de lo múltiple, como el de Nietzsche. La identidad, tan buscada por esa filosofía latinoamericana mayoritaria, es una ansiedad antigenealógica. En ese sentido, esa filosofía y su procedencia no es solo eurocéntrica, como ya ha sido expuesto por otros comentaristas, sino reactiva, y esto vale para tres de sus tendencias principales: la filosofía normalizadora, la corriente historicista y la filosofía latinoamericana de la liberación. De ahí, de paso, la fascinación de dicho pensamiento con la idea de carencia —nunca hemos sido lo suficientemente civilizados—. Esto ha instaurado un cuerpo sufriente en América Latina, atrapado en la dialéctica de la víctima y el victimario. Se trata entonces de pensar con Nietzsche para intentar pensar sin resentimiento desde América Latina y sobre esta. ¿Nietzsche en América Latina? Sí, pero más allá de los estudios de recepción e influencia: Nietzsche como aquel estruendo capaz de infundirle una dimensión geológica del pensamiento.
cnd-1/NeuroD1 Functions with the Homeobox Geneceh-5/Vax2 and Hox Geneceh-13/labial To Specify Aspects of RME and DD Neuron Fate inCaenorhabditis elegans
Authors: Aquino-Nunez Wendy , Mielko Zachery E , Dunn Trae , Santorella Elise M , Hosea Ciara , Leitner Lauren , McCalla Derrica , Simms Claire , Verola Wendy M , Vijaykumar Sharanya , Hudson Martin L
Published: June 2020

Identifying the mechanisms behind neuronal fate specification are key to understanding normal neural development in addition to neurodevelopmental disorders such as autism and schizophrenia. In vivo cell fate specification is difficult to study in vertebrates. However, the nematode Caenorhabditis elegans, with its invariant cell lineage and simple nervous system of 302 neurons, is an ideal organism to explore the earliest stages of neural development. We used a comparative transcriptome approach to examine the role of cnd-1/NeuroD1 in C. elegans nervous system development and function. This basic helix-loop-helix transcription factor is deeply conserved across phyla and plays a crucial role in cell fate specification in both the vertebrate nervous system and pancreas. We find that cnd-1 controls expression of ceh-5, a Vax2-like homeobox class transcription factor, in the RME head motorneurons and PVQ tail interneurons. We also show that cnd-1 functions redundantly with the Hox gene ceh-13/labial in defining the fate of DD1 and DD2 embryonic ventral nerve cord motorneurons. These data highlight the utility of comparative transcriptomes for identifying transcription factor targets and understanding gene regulatory networks.
The Middle East challenge to the Nuclear Weapons Ban Ttreaty
Authors: Rajmil Daniel
Published: June 2020

La histórica aprobación en julio de 2017 de un tratado para la prohibición de armas nucleares, in-cluso si está lleno de complejidades, puede representar un avance hacia su eliminación mundial. Además, el tratado refuerza el papel central de las Zonas Libres de Armamento Nuclear (ZLAN) como pasos decisivos en los procesos de desarme regional como en el caso de Próximo Oriente. En este documento se presenta un análisis de las opiniones políticas de los países de la región así como de los parámetros de su votación final. En un contexto de incertidumbre global, con dinámi-cas de disuasión renovadas, examinar la posible limitación del uso de armas nucleares a través de un estudio regional, ofrece una interesante visión del estado actual de las relaciones in-ternacionales.
Necessidades dos produtores de hortaliças e tabaco do sul do Rio Grande do Sul em relação a mecanização
Authors: Custódio Tiago Vega , Spagnolo Roger Toscan , Oldoni André , Maltzahn Latóia Eduarda , Machado Antônio Lilles Tavares
Published: June 2020

A agricultura familiar é responsável por uma parcela importante da produção agrícola do país, entretanto se depara com deficiências principalmente no que se refere às máquinas agrícolas compatíveis com suas necessidades. Neste contexto, a abordagem do presente estudo foi caracterizar as demandas dos produtores familiares da região sul do Rio Grande do Sul, em relação a mecanização utilizada na produção de hortaliças e tabaco. As informações foram coletadas junto aos produtores por meio de entrevistas. Utilizou-se um questionário semiestruturado, o qual, permitiu a combinação de perguntas abertas e fechadas. Constatou-se que os produtores familiares que produzem hortaliças e tabaco na região estudada, necessitam de um sistema mecanizado capaz de formar canteiros e depositar fertilizantes em uma única operação. Além disso o equipamento deve possuir baixo custo e de fácil abastecimento. Também foi constatado que os tratores de quatro rodas utilizados pelos produtores variam entre 36,77 e 62,52 kW de potência no motor.
Autobiografia: as mutações de um fértil gênero
Authors: Zimmermann Jian Marcel
Published: June 2020

Este trabalho tem como intuito refletir sobre uma modalidade narrativa amplamente difundida na contemporaneidade, a autobiografia. Interessa-nos, neste sentido, sua vertente literária, as autobiografias que galgam o status de arte. Claro está que não se trata de um gênero estanque ou limitado às formas convencionais, sendo que um de nossos propósitos é verificar as soluções estéticas de renovação deste objeto. Como corpus de análise, elegemos o romance A Favor do Vento, de Duca Leindecker, músico com larga e bem sucedida carreira, principalmente como líder da banda Cidadão Quem, e escritor de três livros, com boa aceitação do público leitor. Julgamos que A Favor do Vento configura-se como uma autobiografia não convencional, pelo uso de artifícios que manejam constantemente a ação de cifrar e decifrar, dando ao leitor relevante tarefa na efetivação do texto literário. A avaliação das possibilidades estéticas utilizadas nas narrativas em que autor e personagem compartilham o mesmo contexto axiológico é, sem dúvida, uma reflexão pungente na contemporaneidade, e nosso propósito aqui é modestamente contribuir na construção deste panorama tão vário.
Development of SCAR markers related to heat tolerance in Kentucky bluegrass
Authors: TU Mingyue , HE Yali , LI Xiaoli , ZOU Ying , YUAN Xiaojun
Published: June 2020

As a high-quality cool-season grass, Kentucky bluegrass (Poa pratensis) is facing increasing threat of high temperature, so improving its heat tolerance (HT) has become an important breeding target. In this study, the HT of 84 materials was identified in the artificial climate chamber, and 15 most heat-tolerant and 15 most heat-sensitive materials were selected respectively to construct two DNA pools. There was a significant difference in high-temperature tolerance time between the plants in the two pools, which was more than 22 days. A total of 304 sequence-related amplified polymorphism (SRAP) and 88 simple sequence repeat (SSR) markers were used to screen the polymorphic bands between the two pools. Then, these bands were transformed into sequence characterized amplified region (SCAR) markers, and finally 12 SCAR dominant markers related to HT were obtained, which could detect the heat-sensitive materials efficiently. Among them, S-me8×em2 and S-me52×em5 had the best identification effect, and the consistency between the absence of these two markers and the heat-sensitive phenotype was 87%. According to the comparison with NCBI database, the sequences of 12 SCAR markers had no homology with known HT related genes. Next, we would further verify the HT identification efficiency of these SCAR markers in single plants within materials, and try to use them in molecular marker-assisted breeding.
Priming improves germination and seed reserve utilization, growth, antioxidant responses and membrane stability at early seedling stage of Saudi sorghum varieties under drought stress
Authors: TOUNEKTI Taieb , MAHDHI Mosbah , AL-FAIFI Zarraq , KHEMIRA Habib
Published: June 2020

Seeds of three sorghum (Sorghum bicolor (L.) Moench.) varieties from Southwest Saudi Arabia were used to investigate the potential of osmopriming with polyethylene glycol (PEG 8000) to improve germination performance, seed reserve utilization and early seedling growth and drought stress tolerance. The primed (PS) and unprimed (UPS) seeds of the three sorghum varieties were germinated for 8 days under increasing PEG-induced osmotic stress. The treatments were arranged in a completely randomized design, in a factorial arrangement, with three sorghum cultivars (‘Zaydia’, ‘Shahbi’ and ‘Ahmar’) and four osmotic potentials (0.0; -0.4; -0.8 and -1.2 MPa) with four replicates of 50 seeds each. The results showed that drought stress affected seed germination and seedling emergence and establishment, but increased the activity of the antioxidant enzyme catalase (CAT). The strongest inhibition of germination and growth occurred at the highest PEG concentration and a significant difference was noticeable between the studied varieties. We confirmed also that seed osmopriming improved seed germination performance, seedling growth and enhanced the CAT activities while reduced malonyldialdehyde (MDA) accumulation and electrolyte leakage (EL) in the drought-stressed seedlings. Seed priming have enhanced also the α-amylase and total proteases activities in all varieties. The largest increase of these hydrolysing enzymes was shown in ‘Ahmar’. Furthermore, the PEG priming lead to improvement of the weight of utilized (mobilized) seed reserve (WUSR), seed reserve depletion percentage (SRDP) and total seedling dry weight (SLDW) of sorghum seedlings under water stress conditions. Still, the highest values or all three parameters were found in the ‘Ahmar’ variety. Under increasing drought stress conditions, ‘Ahmar’ showed the highest yield stability index (YSI) and the least EL and MDA contents in comparison to the other two varieties during the seedling establishment stage. Therefore, the former variety can tolerate better a rigorous water stress condition. ‘Zaydia’ appears to be the most vulnerable to drought stress. Thus, the use of species or varieties with eminent seed metabolic quality is an advantageous trait in drought-prone regions.
Phenolic composition and antioxidant activity of red, rosé and white wines originating from Romanian grape cultivars
Authors: BANC Roxana , LOGHIN Felicia , MIERE Doina , RANGA Floricuta , SOCACIU Carmen
Published: June 2020

The objective of this work was to study the phenolic profile and composition in relation to antioxidant activity of fifteen samples of commercial red, rosé and white wines originating from six native grape varieties and produced in important wine regions from Romania. The profile and quantification of major phenolic compounds were performed by direct injection of wines in the LC-MS system, using DAD and ESI (+) MS techniques, in parallel with the total phenolic content (TPC) measured by spectrometry and the free radical scavenging activity, against 2,2-diphenyl-1-picrylhydrazyl (DPPH). There were identified 38 polyphenols in wines, including 3 flavan-3-ols, 17 flavonols, 12 anthocyanins and 6 stilbenes. The red wines had significant higher phenolic content and antioxidant capacity, followed by rosé and white wines. The richest phenolic content and antioxidant activity was obtained for ‘Feteasca Neagra’ (Tohani) among red wines and for ‘Feteasca Regala’ (Jidvei) among white wines. TPC values were positively correlated with the antioxidant capacity in all white wines and only for the red ‘Feteasca Neagra’ assortment, while for the ‘Babeasca Neagra’ assortment negative correlations were obtained. From the 38 variables, flavan-3-ols have exerted the greatest influence on wine differentiation, based on their colour (red, rosé and white). The study also revealed significant differences between cultivars, both qualitative and quantitative, in terms of their polyphenolic composition, that could be important in the cultivar authentication of wines from these varieties.
Effect of salinity stress on yield and quality parameters in flax (Linum usitatissimum L.)
Authors: DUBEY Saijasi , BHARGAVA Atul , FUENTES Francisco , SHUKLA Sudhir , SRIVASTAVA Shilpi
Published: June 2020

Flax is one of the oldest utilitarian plants that have been grown for fibre as well as an oilseed crop. The species has been recognized as an excellent source of micronutrients, dietary fibre, protein, vitamin B1, lignan, and essential fatty acids (EFA), namely linoleic and α-linolenic acids. However, in spite of immense nutritional and industrial importance of the crop no work has been carried out on the effect of salinity induced by different salts on seed yield and quality traits in Linum usitatissimum. A high yielding germplasm line ‘Mukta’ was subjected to five concentrations (0 mM, 50 mM, 100 mM, 150 mM and 200 mM) of three salts viz. sodium chloride (NaCl), potassium chloride (KCl) and calcium chloride (CaCl2) for two seasons. Data were collected for seed yield along with different quality traits and a range of antioxidant enzymes. Seed yield decreased with rise in salt concentration and was minimum at 200 mM for all the salts. Chlorophyll a, chlorophyll b and carotenoid content continuously decreased with increase in salt concentration for all the salt treatments. Catalase and GST content increased with increase in salt concentration and was maximum at 200 mM.
In vitro germination and bulblet and shoot propagation for wild edible Eremurus spectabilis M.Bieb.
Authors: TUNCER Burcu
Published: June 2020

Eremurus spectabilis M.Bieb is consumed as a vegetable because of its nutritious characteristics. The plants are also used for medicinal purposes, in the cut flower industry as an ornamental geophytes, and in industry as a natural adhesive. The aim of the present study was to improve the in vitro propagation protocol (in vitro germination and bulblet and shoot formation) of E. spectabilis. For this purpose, E. spectabilis seeds were in vitro germinated in four different nutrient media: Murashige and Skoog (MS), Gamborg (B5), White (WH), and Shenk and Hildebrandt (SH). To stimulate bulblet and/or shoot regeneration, hypocotyls of 35-40-day-old in vitro-germinated plantlets were cut into 0.5-1.0 cm pieces, and the resultant explants were cultured in MS media containing 2,4-dichlorophenoxyacetic acid (2,4-D) (0.5, 1.0, 2.0, and 4.0 mg L-1) + Kinetin (0.5 mg L-1), Thidiazuron (TDZ) (0.5, 1.0, 2.0, and 4.0 mg L-1) + 1-Naphthylacetic acid (NAA) (0, 0.1, 0.5, and 1.0 mg L-1), and 6-Benzylaminopurine (BAP) (0.5, 1.0, 2.0, and 4.0 mg L-1) + 2,4-dichlorophenoxyacetic acid (2,4-D) (0, 0.1, 0.5, and 1.0 mg L-1). The best outcomes for germination ratio (57.5%) were obtained from the B5 medium. In the third set of in vitro propagation experiments, 100% bulblet formation was achieved in TDZ (0.5 mg L-1) and NAA (0.5 and 0.1 mg L-1) combinations of MS media, and this was followed by 0.5 mg L-1 BAP-containing medium (81.3%). Shoot formation ratios with the same media combinations varied from 60-70%, and the number of shoots per explant varied from 1.4-2.4 shoots. Further in vitro propagation research is planned with larger bulb sizes to develop a protocol for rooting bulblets and/or shoots.
Biological activities of in vitro liverwort Marchantia polymorpha L. extracts
Authors: TRAN Tan Q. , PHAN Hoang N. , BUI Anh L. , QUACH Phuong N. D.
Published: June 2020

To overcome the problems in liverwort collecting such as small size and easily mixed with other species in the wild, we have successfully cultivated Marchantia polymorpha L. under in vitro conditions in the previous study. The aim of this study is to evaluate the biological activities of this in vitro biomass as a confirmation of the sufficient protocol in cultivation this species. Cultured biomass was dried at a temperature of 45-50 oC to constant weight and ground into a fine powder. The coarse powder was extracted with organic solvents of increasing polarization including n-hexane, chloroform, ethyl acetate, and ethanol using the maceration technique. Four extracts were investigated antioxidant (iron reduction power, DPPH), antibacterial (agar diffusion), tyrosinase inhibitory activity, anti-proliferation on MCF-7 cells. Additionally, the presence of natural metabolite groups of the extracts was detected by using specific reagents. For antioxidant activity, ethyl acetate fraction extract had the highest iron reducing power and DPPH free radical scavenging ability with IC50 = 439.31 µg ml-1. All three n-hexane, chloroform, and ethyl acetate extracts possessed resistance to the bacterial strain tested. At a concentration of 2 mg ml-1, n-hexane and chloroform extracts had the highest percentage of tyrosinase inhibition (69.54 and 69.10%, respectively). The n-hexane extract is a potent extract that inhibits the proliferation of MCF-7 cells with the lowest IC50 of 38.15 µg ml-1. A preliminary chemical composition survey showed that the cultured biomass liverwort contains many bioactive compounds, particularly the compounds of range of non- and less-polarized fractions.
Enhanced production of valtrate in hairy root cultures of Valeriana jatamansi Jones by methyl jasmonate, jasmonic acid and salicylic acid elicitors
Authors: ZHAO Shuang , TANG Hong
Published: June 2020

Valtrate is a pharmacologically active epoxyiridoid ester found in the roots and rhizomes of Valeriana jatamansi Jones. The plant produces only small amounts of this metabolite naturally, and so induction of hairy roots as well as elicitation can be useful to increase its commercial production. In this study, strain R1601 of Agrobacterium rhizogenes was used to induce hairy roots in V. jatamansi, and stable hairy root cultures of V. jatamansi were established successfully. The influence of three exogenous elicitors including methyl jasmonate (MJ), jasmonic acid (JA) and salicylic acid (SA) on valtrate production in the hairy root cultures of V. jatamansi was also investigated, and the 25-day-old hairy root cultures were treated with different concentrations of the elicitors at exposure time of 7 days. This present study showed that MJ (100 mg/L) highly promoted valtrate production at 7 days after elicitation, to a level of 3.63 times higher than that of non-elicited control. SA did not significantly increase the production of valtrate. This is the first-time study to assess the elicitation of hairy root cultures to promote valtrate biosynthesis in V. jatamansi and the resulting experiments demonstrated that MJ was indeed a potent inducer of valtrate biosynthesis.
Spring and autumn phenology in sub-mesothermal beech stands from the southwestern extremity of the Carpathians
Authors: POPESCU Radu , ȘOFLETEA Neculae
Published: June 2020

The research carried out was aimed to assessing the phenological behavior of beech (Fagus sylvatica L.) in the southwestern area of the Carpathians, in submesothermal forest sites, differentiated from the majority mesothermal ones of this species. The data obtained may be used for predicting the phenological changes of the species, especially in the Carpathian area, under the future influence of expected climate change. Assessments for spring and autumn phenology (buds burst -BB and foliation, flowering and leaves senescence) were carried out on a transect with a difference in altitude of 1000 meters, in phenological research areas located at 200 m, 700 m and 1200 m. At each altitude level, 100 trees of I and II Kraft classes were phenologically characterized: 50 trees on the south-facing slope (sunny exposure) and 50 on the north-facing slope (shade exposure).The phenological data were interpreted in relation to climate data recorded in each area by a HOBO U23 Pro v2 sensor. The site conditions of submesothermal climate in the low altitude area led to DOY (day of the year) values below 100. The phenological differentiation of populations is evident in relation with the altitude, while at the same altitudinal level the influence of the exposure was much lower. The gradiental values by altitude sectors highlighted the nonlinearity of the development of foliation phenophase, the value being lower in the first 500 m, where the beech is under the impact of the submesothermal climate. It has been proven both the dependence of the foliation onset depending on the cumulation of temperatures in relation to the DOY moment and also on the values recorded throughout the vegetative rest. The altitudinal gradiental values resulting for flowering in the first and second altitudinal half of transect also differentiate the stands, but are lower than that resulting for BB. The leaves senescence has a delay of 1.8 up to 2.4 days per 100 meters altitude, and the length of the vegetation season is reduced more sharply in the upper half of the analyzed altitudinal transect. The sub-mesothermal climate could be involved in condensation of spring phenophases in the stands of the lower half of the researched area. Our data may be used for predicting the phenological changes, especially in the Carpathian area, under the expected climate change.
Impact of essential oils of clove Syzygium aromaticum in rats exposed to stress by nickel
Authors: ADLI Djallal E. H. , GRELE Karima , BORSALI Amine H. , BRAHMI Mostapha , ARABI Wafaa , TAIBI Narimane , SLIMANI Miloud , KAHLOULA Khaled
Published: June 2020

The mechanisms that cause nickel (Ni) toxicity are multiple and potentially affect all cells in the body. For this purpose, we were interested in the oxidative stress induced by the Ni at the erythrocyte level at a dose of 2 g/l during the gestation and lactation period in the Wistar rats and the capacity of the clove essential oil, Syzygium aromaticum, (CEO) to restore or not this state of stress. Extraction of the CEO by hydro-distillation allowed us to obtain a CEO with a yield of 10.60% and the characterization of this essential oil by GC-MS indicates that the major components of this oil are: Eugenol (80.95%), eugenyl acetate (10.48%), β-caryophyllene (7.21%) and α-humulene (0.87%). The antioxidant activity of the CEO made in vitro showed a free radical scavenging capacity DPPH with an IC 50 of the order of 25.60 μg/ml. In addition, analysis of the erythrocyte antioxidant status indicated that Ni significantly increased the enzymatic activities of catalase (CAT) and superoxide dismutase (SOD) and significantly decreased the enzymatic activity of glutathione peroxidase (GPx), resulting in dysfunction of the antioxidant defense system. On the other hand, the administration of CEO by intraperitoneal (IP) over a period of 21 days to rats previously intoxicated with Ni, indicates that this CEO contributes significantly in improving defenses against free radical aggression, through a recovery. At the level of antioxidant enzyme activities by increasing their abilities to eliminate radical compounds.
Role of active transport of potassium to leaves in the mechanisms of tolerance to salinity in common bean (Phaseolus vulgaris L.)
Authors: ARTEAGA Sugenith , BOSCAIU Monica , PROHENS Jaime , VICENTE Oscar
Published: June 2020

Biochemical markers are of great utility in screening for salt tolerance of crops. In common beans (Phaseolus vulgaris), lower levels of proline under stress have been associated with a better stress resistance of cultivars. In the present study, the responses to salinity have been analysed in six cultivars of common beans: four local landraces from Spain and two experimental lines from Cuba. Proline was used for ranking the relative tolerance of the cultivars, confirming a previous study which reported as more stress-tolerant two of the Spanish landraces. Total soluble sugars concentrations varied with treatments and between genotypes, but it was difficult to assess their role in stress tolerance of the analysed plants. Sodium concentration in leaves was the lowest in one of the two salt-resistant cultivars, and potassium did not vary or even increased under salt stress in all of them, except for the most susceptible one, where a drop of this cation was registered under 150 mM NaCl. Changes in malondialdehyde (MDA) contents did not indicate salt-induced membrane peroxidation resulting from secondary oxidative stress; consequently, accumulation of total phenolic compounds and flavonoids, as an antioxidant defence mechanism, was not detected. These results highlight the reliability of using proline as a biochemical marker of salt stress in common beans and the importance of the mechanism related to potassium transport to leaves in conferring stress tolerance to some common bean cultivars.
Introduction pages
Authors: SESTRAS Radu E.
Published: June 2020

Notulae Scientia Biologicae (http://www.notulaebiologicae.ro), Issue 2, Volume 12, 2020: The papers published in this issue represent interesting novelties in different topics of life science. Among the exciting researches, we invite readers to find news about: evaluation of phytochemical constituents and in vitro antimicrobial activities of leaves extracts of Calotropis procera against certain human pathogens; in vitro anti-urease, antioxidant, anticholinesterase, cytotoxic and in vivo anti-inflammatory potential of Satureja cuneifolia; impact of essential oils of clove Syzygium aromaticum in rats exposed to stress by nickel; young capitulum as important explant in in vitro mass propagation of gerbera (Gerbera jamesonii); a comparative study between temporary immersion system and semi-solid cultures on shoot multiplication and plantlets production of two Moroccan date palm (Phoenix dactylifera L.) varieties in vitro; effect of pretreatments on germination of seeds of the timber plant, Terminalia ivorensis and Mansonnia altissima; abundance, frequency and distribution pattern of tree species in recorded forest area of Western Himalaya; role of active transport of potassium to leaves in the mechanisms of tolerance to salinity in common bean (Phaseolus vulgaris L.).