bluuebunny/crossref_metadata_2025_split huggingface dataset:
Action Potentials: Generation and Propagation
Authors: Fouda Mohamed A , Ruben Peter C 
Published: July 2020

Abstract

All cells maintain a voltage across their plasma membranes. However, only excitable cells can generate action potentials, the rapid transient changes in membrane potential that spread along the surface of these unique cells. Action potential generation and propagation occur through and is regulated by, the function of voltage‐gated ion channels. These channels are proteins with ion‐selective pores that span the cell membrane. Ion channels undergo changes in their structural conformation in response to changes in the electrical field across the membrane. These structural changes cause the opening of the channels' pores through which ions can flow down their electrochemical gradient. The charge carried by ions creates an electrical current and rapidly alters the membrane potential with time and voltage‐dependent properties. This rapid, transient membrane potential change is called the action potential. Action potentials transmit information within neurons, trigger contractions within muscle cells, and lead to exocytosis in secretory cells.

Key Concepts

Rapid changes in membrane ion permeabilities generate action potentials.

Ion channels are transmembrane proteins that control the passage of ions. Voltage‐gated sodium ion channels play a crucial role in the development of action potential.

Action potential is ‘all or none’ response.

Refractory Period is the time when it is physiologically impossible to elicit another action potential.

Action potential propagation changes in a ‘day/night’ dependent manner ‘circadian rhythm’.
Dopamine
Authors: Bannon Michael J , Bannon Erin E , Bannon Kellen T 
Published: July 2020

Abstract

Dopamine is a neurotransmitter (or chemical messenger) found in diverse organisms ranging from invertebrates to humans. It is also a required intermediate in the formation of the neurotransmitters noradrenaline and adrenaline. Although found in a number of vertebrate tissues, dopamine's most important effects are due to robust expression in a relatively small number of central nervous system neurones that have widespread projections. Dopamine signalling affects a correspondingly wide variety of physiological functions, from gastrointestinal motility and pituitary hormone release, to voluntary movements, motivation and reward, and higher cognitive processes. Although dopamine neurotransmission is normally a highly regulated process, drugs have been developed to modify its signalling. Some commonly used drugs affect dopamine neurotransmission indirectly (by changing its synthesis, storage, release, reuptake or inactivation), whereas other drugs more directly mimic or block the actions of dopamine at its biological targets (i.e. multiple cell surface dopamine‐responsive receptors). An astonishingly broad range of central nervous system disorders (including Parkinson disease, schizophrenia, attention deficit hyperactivity disorder and sleep disorders), and other medical conditions (such as nausea, excessive pituitary hormones, gastrointestinal disorders and cardiovascular shock) are currently treated using such drugs.

Key Concepts

Dopamine is a neurotransmitter in the brain and elsewhere, as well as an intermediate in the biosynthesis of the neurotransmitters noradrenaline and adrenaline.

Dopamine synthesis is regulated by a rate‐limiting enzyme, and its extracellular concentrations controlled by an active recapture mechanism and several metabolic enzymes.

The effects of dopamine are mediated by a family of G protein‐coupled receptors linked to distinct intracellular signalling pathways.

Though relatively few in number, dopamine‐containing neurons originating in the mammalian midbrain send branching fibres that innervate widespread areas of the forebrain.

Brain dopamine influences learning and execution of voluntary movements, motivation, reward, attention and working memory.

Disturbances in dopamine neurotransmission have been implicated in a number of CNS disorders but shown most conclusively in Parkinson disease and drug abuse.

Drugs that modify CNS dopamine neurotransmission are used to treat a variety of disorders including Parkinson disease, schizophrenia, attention deficit hyperactivity disorder, sleep disorders and nausea.

Dopamine receptors outside of the CNS are targets in the medical treatment of excessive pituitary hormone release, certain gastrointestinal disorders and cardiovascular shock.

The extensive study of this simple neurotransmitter system has led to fundamental discoveries regarding cellular and molecular mechanisms contributing to normal brain function and human disease.
DNADamage
Authors: Placentra Victoria , Limpose Kristin , Corbett Anita , Doetsch Paul 
Published: July 2020

AbstractDeoxyribonucleic acid (DNA) encodes the information necessary for all functions of life. Despite the critical importance of DNA, its chemical structure is susceptible to chemical and physical alterations including base damage and single‐ and double‐strand break (DSB) induction. Cellular DNA damage results from both environmental exposures and endogenous sources from normal cellular metabolism. DNA damage in both the nuclear and mitochondrial genomes is associated with several human diseases including the development of cancer. The biological consequences of DNA damage are largely determined by a cell's DNA repair capabilities and the interaction of damaged DNA with the replication and transcription machinery. Technologies exist for the detection and measurement of cellular DNA damage in varying contexts.Key ConceptsEstimated rates of induction of various deoxyribonucleic acid (DNA) lesions, including spontaneous hydrolysis and oxidative DNA damage, have been determined.Potential biological consequences of DNA damage include physiological conditions such as cancer, neurodegenerative diseases, heart disease and ageing.Various exogenous and endogenous sources induce DNA base lesions and strand breaks that can be detected by molecular and biochemical methods.Incorporation of damaged deoxyribonucleotides during DNA synthesis can occur due to errors committed by DNA polymerases and/or disruptions of nucleotide pool balance.Many of the features resulting from DNA packing into chromatin, including DNA–protein interactions and sequence context, greatly impact how damage is distributed within the genome.Mutational signatures of cancers arise from context‐dependent DNA damage and can be attributed to specific types of DNA damage.DNA is often the target of chemotherapeutic drugs used to treat cancer, resulting in tumour cell death.Mitochondrial DNA damage can increase reactive oxygen species, leading to cell death and in certain instances give rise to mutations that contribute to cancer phenotypes.
XenopusEmbryo: Neural Induction
Authors: Monsoro‐Burq Anne‐Hélène 
Published: July 2020

AbstractIn vertebrate embryos, the future nervous system forms during early development by a series of molecular events named neural induction. This includes the early action of mesoderm‐derived fibroblast growth factors (FGFs), followed by the blockade of bone morphogenetic protein (BMP) signalling by the dorsal mesoderm during gastrulation, and finally comprises the regionalisation of the neural plate along the anterior‐posterior and medial‐lateral axes, under the complex and combined actions of FGFs, retinoids and Wnts. Founding experiments using frog embryos have initiated intensive research on neural induction 90 years ago. Molecular approaches combined with classical experimental embryology strategies provide a powerful way of deciphering those intricate regulations in frogs and more recently in other vertebrates. The current model of neural induction in the frog model systemXenopus,is largely conserved between aquatic species and amniotes. This model was recently updated to describe neural induction in the posterior spinal cord.Key ConceptsThe formation of neural precursors from the embryonic ectoderm is one of the earliest embryonic inductions.Neural induction results in the formation of a neural plate regionalised along its anterior‐posterior and medial‐lateral axis.Neural induction is subdivided into at least three steps: acquisition of neural competence, induction of anterior neural tissue and posteriorisation of the neural tissue.Almost a century after the discovery of the Spemann–Mangold organiser in frogs, the exploration of the molecular mechanisms driving neural induction remains a very active field of research.The models and molecular mechanisms discovered in frogs are largely conserved in other vertebrates including amniotes.
Ethical Issues in Multiplex Genetic Testing
Authors: Kilbride Madison , Bradbury Angela 
Published: July 2020

AbstractAs a result of technological advancements, multiplex (or multigene) genetic tests are increasingly available both inside and outside the clinical setting. Multiplex genetic tests include: expanded carrier screening (ECS), preimplantation genetic testing (PGT), prenatal genetic diagnosis (PND), newborn screening (NBS), predictive genetic testing, diagnostic genetic testing, whole‐genome sequencing (WGS) and whole‐exome sequencing (WES). Many of these tests include dozens – even hundreds – of genes that are associated with a wide range of genetic conditions. While multiplex genetic tests have significant advantages over more targeted approaches, they also raise ethical concerns, related to informed consent, the implications of genetic selection and uncertainty. Outside the clinical setting, direct‐to‐consumer (DTC) genetic testing also raises a set of ethical concerns, including some that are specific to the DTC model.Key ConceptsMultiplex genetic testing has important advantages over targeted approaches, including efficiency, cost‐effectiveness and the detection of unanticipated genetic risks.There are different types of multiplex genetic tests.Multiplex genetic testing raises ethical concerns about informed consent, the implications of genetic selection and uncertainty.Obtaining informed consent to multiplex genetic testing is challenging because multiplex tests often analyse genes that are associated with a range of diseases, penetrance estimates and medical management strategies.Genetic testing, particularly of embryos and fetuses, raises ethical concerns about genetic selection for or against certain traits.Multiplex genetic tests can lead to significant uncertainty for patients interested in learning about their own genetic risks or those of their current or future children.Multiplex genetic testing is increasingly available through direct‐to‐consumer (DTC) platforms, raising unique ethical questions about the nature of informed consent outside the clinical setting.In order to realise the promise of multiplex genetic tests, there is a need to continue studying the risks and benefits of different types of tests by collecting and evaluating outcome data.
The First Flexible Dual‐Ion Microbattery Demonstrates Superior Capacity and Ultrahigh Energy Density: Small and Powerful
Authors: Liu Qianwen , Zhang Guofeng , Chen Nan , Feng Xixi , Wang Chengzhi , Wang Jiaqi , Jin Xuting , Qu Liangti 
Published: July 2020

AbstractHumans live today in a high‐tech and informationalized society. With the development of the emerging electronic information age, various electronic systems are inclined to be multifunctional and miniaturized. It is urgent to develop “small and powerful” micro‐batteries with flexibility and high electrochemical performance to meet the diverse needs of microelectronic components. However, low electrochemical performance exists in traditional microenergy storage devices, which fail to satisfy the energy needs for microdevices. Here, for the first time, a planar integrated flexible rechargeable dual‐ion microbattery (DIMB) is reported, which is fabricated from an interdigital pattern of graphite as an electrode and lithium hexafluorophosphate as an electrolyte. As a microbattery, the DIMB exhibits a high reversible capacity of 56.50 mAh cm−3, and excellent cycle stability with 90% capacity retention after 300 cycles under a high working voltage. The application of DIMB in microdevices, such as light‐emitting diodes (LEDs), digital electronic game consoles, and electrochromic glasses is also investigated, fully demonstrating its “small and powerful” performance. The integrated DIMB is a high‐voltage microdevice that reaches a nonpareil discharge voltage of about 100 V and a charging capacity of 102 mAh g−1. This dual ion‐based flexible microbattery could become a promising candidate for energy storage and conversion components in next‐generation microelectronic devices and integrated electronic devices.
Endocytosis‐Enabled Construction of Silica Nanochannels Crossing Living Cell Membrane for Transmembrane Drug Transport
Authors: Pan Xi , Xu Dandan , Tang Xiuzhen , Liu Ning , You Yongqiang , Wang Xianqiao , Yan Xiaohui , Ma Xing , Chen Xiaoyuan 
Published: July 2020

AbstractArtificial transmembrane channel (ATC) analogs are developed for overcoming biological membrane barriers and realizing transmembrane drug delivery, which are mostly studied within artificial lipid bilayers and thus lacked enough stability in practical applications on living cells. Here, natural endocytosis of silica‐based 1D nanomaterials (nanowires) with an ultrahigh aspect ratio is investigated. Enlightened by partially endocytosed ultralong silica nanowires, ATC that can penetrate living cell membranes for transmembrane transportation of small drug molecules is creatively constructed, resulting in enhanced drug delivery efficacy and decreased the half maximal inhibitory concentration. For the first time, an in‐depth study of the cellular uptake of 1D nanomaterials with ultrahigh aspect ratios (from 10 to 120) into living cells is carried out. Through confocal laser scanning microscopy observation, the endocytosis process of ultralong nanowires, including full uptake of short nanowires and partial uptake of longer nanowires, is clarified. Theoretical simulation is performed to give a fundamental understanding on the endocytosis mechanism of ultralong 1D silica nanowires. The simulation results demonstrate the time‐dependent internalization dynamics of the nanowires, which agrees well with our experimental results. This work not only clarifies the cellular interaction between 1D nanomaterials and living cells, but also pioneers the use of natural endocytosis of 1D nanomaterials for constructing ATC.
Gram‐Scale Synthesis of High‐Loading Single‐Atomic‐Site Fe Catalysts for Effective Epoxidation of Styrene
Authors: Xiong Yu , Sun Wenming , Xin Pingyu , Chen Wenxing , Zheng Xusheng , Yan Wensheng , Zheng Lirong , Dong Juncai , Zhang Jian , Wang Dingsheng , Li Yadong 
Published: July 2020

AbstractSingle‐atomic‐site (SAS) catalysts, a new frontier of catalysts, always show extremely high atom efficiency and unexpected catalytic properties. Herein, a pyrolyzing coordinated polymer (PCP) strategy is developed, which is facile and widely applicable in the synthesis of a series of SAS catalysts including SAS‐Fe, SAS‐Ni, SAS‐Cu, SAS‐Zn, SAS‐Ru, SAS‐Rh, SAS‐Pd, SAS‐Pt, and SAS‐Ir. The as‐obtained SAS catalysts can be easily synthesized at gram scale and the metal loading of SAS‐Fe catalysts achieves a record value of 30 wt%, which meets the requirement of practical applications. Moreover, it is discovered that SAS‐Fe catalysts show unprecedented catalytic performance for epoxidation of styrene using O2 as the only oxidant (yield: 64%; selectivity: 89%), while Fe nanoparticles and ironporphyrin are inactive. This discovery is believed to pave the way for exploiting the unparalleled properties of SAS catalysts and promoting their industrial applications.
Engineering the Phases and Heterostructures of Ultrathin Hybrid Perovskite Nanosheets
Authors: Sun Yan , Yin Yao , Pols Mike , Zhong Jingxian , Huang Zhen , Liu Bowen , Liu Jinqiu , Wang Wei , Xie Hongguang , Zhan Guixiang , Zhou Zishu , Zhang Wei , Wang Pengcheng , Zha Chenyang , Jiang Xiaohong , Ruan Yinjie , Zhu Chao , Brocks Geert , Wang Xiaoyong , Wang Lin , Wang Jianpu , Tao Shuxia , Huang Wei 
Published: July 2020

AbstractLow‐dimensional perovskites have gained increasing attention recently, and engineering their material phases, structural patterning and interfacial properties is crucial for future perovskite‐based applications. Here a phase and heterostructure engineering on ultrathin perovskites, through the reversible cation exchange of hybrid perovskites and efficient surface functionalization of low‐dimensional materials, is demonstrated. Using PbI2 as precursor and template, perovskite nanosheets of varying thickness and hexagonal shape on diverse substrates is obtained. Multiple phases, such as PbI2, MAPbI3 and FAPbI3, can be flexibly designed and transformed as a single nanosheet. A perovskite nanosheet can be patterned using masks made of 2D materials, fabricating lateral heterostructures of perovskite and PbI2. Perovskite‐based vertical heterostructures show strong interfacial coupling with 2D materials. As a demonstration, monolayer MoS2/MAPbI3 stacks give a type‐II heterojunction. The ability to combine the optically efficient perovskites with versatile 2D materials creates possibilities for new designs and functionalities.
Tetradentate Pt(II) Complexes for Spectrum‐Stable Deep‐Blue and White Electroluminescence
Authors: Zhu Lu , Xie Wentao , Qian Chunyue , Xie Wang , Shen Kang , Lv Anqi , Ma Huili , Li Hongbo , Hang Xiao‐Chun , Li Wenqi , Su Shi‐Jian , Huang Wei 
Published: July 2020

AbstractA new class of tetradentate Pt(II) complexes, Pt(pzpyOczpy‐iPr) and Pt(pzpyOczpy‐mesi), enabling fabrication of deep‐blue and white phosphorescent devices, is successfully synthesized and fully characterized. Their photoluminescent quantum yields in dichloromethane are over 90% with short decay lifetimes less than 4.0 µs. Under low doping concentration, the emission is governed by ligand‐centered triplet transition state (3LC, 3πcz*→πcz) on carbazole group, rendering narrow blue emission with full width at half‐maximum (FWHM) less than 45 nm. When increasing the doping concentration, expanded monomeric and excimeric emissions are demonstrable, displaying broad white emission with FWHM up to 152 nm. Devices fabricated with 2 wt% dopant in DPEPO host achieve a maximum external quantum efficiency (EQEmax) of 17.2% with CIE coordinates of (0.14, 0.15). Otherwise, devices with 50 wt% dopant in mCPCN afford broad white emission with EQEmax of 18.0% and maximum power efficiency of 60.2 lm W−1. More importantly, the concentration‐dependent electroluminescence provides superior stable color under a wide range of current density, revealing a spectrum‐stable emission derived from highly admixed substates in T1.
Highly Linear and Symmetric Weight Modification in HfO2‐Based Memristive Devices for High‐Precision Weight Entries
Authors: Ryu Jin Joo , Jeon Kanghyeok , Kim Guhyun , Yang Min Kyu , Kim Chunjoong , Jeong Doo Seok , Kim Gun Hwan 
Published: July 2020

AbstractIn this study, highly reliable and accurate weight‐modification behaviors are realized using a W/Al2O3 (3 nm)/HfO2 (7 nm)/TiN memristive device. The accuracy of the simulated inference of the MNIST dataset when considering the weight‐modification behavior is ≈95%. It is determined the optimal programming voltage pulsing conditions considering i) a high linearity in the weight‐modification, ii) symmetry between potentiation and depression, and iii) an alleviation of the voltage‐driving circuit overhead for the related part of weight‐modification process. Particular emphasis is placed on the last concern, and thus, the fixed shape of each programming pulse for both potentiation and depression are utilized. The optimal pulse design is 500 µs for the pulse rising, plateau, and falling times and a 2 V amplitude at the absolute scale. Additionally, the nonparametric method to evaluate the linearity and symmetry as opposed to the application of several parametric methods are proposed. The nonparametric method is based on an evaluation of actual data rather than models, and thus considers the actual variability in the conductance change, which is otherwise often ignored in the parameter optimization process.
Agronomic performance of the lignocellulosic feedstock crop energy cane in the Texas Rolling Plains
Authors: Pokhrel Pramod , Rajan Nithya , Jifon John , Rooney William , Jessup Russell , da Silva Jorge , Enciso Juan , Attia Ahmed 
Published: July 2020

AbstractFeedstock genetics and environment are important factors determining biomass yield of biofuel crops. Field studies were conducted to evaluate agronomic performance of four energy cane (Saccharum spp. hybrid) genotypes (TUS11‐62, TUS11‐58, TCP10‐4928, and Ho 02‐113) in the Texas Rolling Plains. In the first study, cane billets were planted in 2015 and data were collected from first (2016) and second (2017) ratoons. A second study was planted in 2016 and data were collected the same year from plant cane. Data collected include biomass, stalk height, stalk population, leaf area index (LAI), and normalized difference vegetation index (NDVI). Biomass yield of ratoons was not significantly different (p > .05) among genotypes. However, TUS11‐58 had the highest plant cane yield. The average biomass yield of plant cane, first, and second ratoons were 20.2, 40.4, and 26.4 t ha−1 respectively. Longer growing period of ratoon (∼8 mo) compared to plant cane (∼5.5 mo) increased biomass. However, low temperatures (−14 to −16 °C) during the dormant phase resulted in lower yield of the second ratoon. Among genotypes, TUS11‐62 had taller stalks, but was cold sensitive. Genotype TCP10‐4928 had higher stalk population and LAI. An exponential relationship was observed between LAI and NDVI (R2 = .67). Overall, there were differences in growth characteristics of energy cane genotypes, however biomass yield was similar in the ratoon phase. The results of this study showed that low temperature tolerance and growing season duration are key factors in determining biomass yield in higher latitude regions such as the Texas Rolling Plains.
Short‐term and long‐term outcomes of laparoscopic colectomy with multivisceral resection for surgical T4b colon cancer: Comparison with open colectomy
Authors: Miyo Masaaki , Kato Takeshi , Takahashi Yusuke , Miyake Masakazu , Toshiyama Reishi , Hamakawa Takuya , Sakai Kenji , Nishikawa Kazuhiro , Miyamoto Atsushi , Hirao Motohiro 
Published: July 2020

AbstractAimIn response to the rising use of laparoscopic surgery, recent studies have shown that laparoscopic multivisceral resections for locally advanced colon cancer are safe, feasible, and provide acceptable oncological outcomes. However, the usefulness of laparoscopic multivisceral resection remains controversial. Here, we aimed to compare short‐term and long‐term outcomes between laparoscopic and open multivisceral resection approaches for treating locally advanced colon cancer.MethodsWe retrospectively collected data on 1315 consecutive patients admitted to the National Hospital Organization, Osaka National Hospital, for surgical treatment of colorectal cancer between 2010 and 2017. We assessed invasiveness in terms of operating times, blood loss, and complications. Oncological outcomes included 5‐year survival rates and recurrences.ResultsWe included 85 patients that underwent a colectomy with a multivisceral resection for locally advanced colon cancer; of these, 38 were treated with a laparoscopic approach and 47 were treated with an open approach. Compared to the open surgery group, the laparoscopic group had significantly less blood loss (median volume: 25 vs 140 mL, P <0.001), a lower complication rate (10.5% vs 29.8%, P = 0.036), and shorter hospital stays (12 vs 15 days, P = 0.028). After excluding patients with stage Ⅳ colon cancer, the groups showed similar pathologic outcomes and no significant differences in 5‐year disease‐free survival (73.9% vs 67.4%; P = 0.664) or 5‐year overall survival (75.8% vs 67.7%; P = 0.695).ConclusionA laparoscopic approach for locally advanced colon cancer could be less invasive than an open approach without affecting oncological outcomes in selected patients.