bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamics of the default mode network in human brain
Authors: Yao Nan , Su Chun-Wang , Li You-Jun , Wang Jue , Zhou Chang-Song , Huang Zi-Gang ,   School of Science, Xi'an University of Technology, Xi'an 710048, China,   Key Laboratory of Biomedical Information and Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China,   School of Physical Science and Technology, Lanzhou University, Lanzhou 730000, China,   Center for Nonlinear Research, Institute of Computing and Theory, Department of Physics, Hong Kong Baptist University, Hong Kong, China
Published: December 2020

Brain is a typical complex system with characteristics such as self-adaptation, self-organization, and multistability. The activity of the default mode network (DMN), a crucial functional subnetwork of the human brain in resting state, obeys typical non-equilibrium statistical mechanical processes in which the system continually switches among multiple metastable states. Revealing the underlying dynamical mechanism of these processes has important scientific significance and clinical application prospects. In this paper, according to the blood oxygen level dependent (BOLD) signals obtained from functional magnetic resonance imaging (fMRI), we build an energy landscape, disconnectivity graph and transition network to explore the non-equilibrium processes of DMN switching among different attractors in resting state. Taking the activities of high-level visual and auditory cortices for examples, we verify the intimate relationship between the dynamics of DMN and the activity modes of these external brain regions, through comparing the distributions in state space and the algorithms such as XGBoost and deep neural networks. In addition, we analyze the interaction between various DMN regions in the resting state by using the techniques such as compressive-sensing-based partial correlation and convergence cross mapping. The results in this paper may presnt new insights into revealing the dynamics of the intrinsic non-equilibrium processes of brain in resting state, and putting forward clinically significant biomarkers for brain dysfunction from the viewpoint of dynamics.
Majorana quasi-particles and superconductor-semiconductor hybrid nanowires
Authors: Yu Chun-Lin , Zhang Hao ,   China Greatwall Quantum Laboratory, Changsha 410006, China,   Department of Physics, Tsinghua University, Beijing 100084, China,   Beijing Academy of Quantum Information Sciences, Beijing 100193, China
Published: December 2020

Majorana fermions are known for being their own anti-particles. As the condensed matter version of Majorana fermions, Majorana quasiparticles have drawn extensive interests for being an ideal candidate for building a fault-tolerant quantum computer, due to their non-abelian statistics. This paper provides an introduction for beginners to the rapidly growing research field of Majorana quasiparticles focusing on one dimensional semiconductor nanowire-superconductor hybrid system. We aim to help readers to quickly understand Majorana quasiparticles and its formation mechanism and the latest experimental results. We first review the theoretical model of the Majorana quasiparticles with its historical background. We then discuss the Kitaev chain and analyze its key elements. We also introduce typical Majorana devices and their corresponding measurement methods. Furthermore, we discuss the observation of robust signatures of Majorana zero modes in recent experiments, with particular attention to tunneling conductance measurements. Finally, we give prospects on future experiments for advancing one dimensional semiconductor nanowire-superconductor hybrid system.
Gauge theory of strongly-correlated symmetric topological Phases
Authors: Ye Peng ,   School of Physics, Sun Yat-sen University, Guangzhou 510275, China
Published: December 2020

In the presence of symmetry-protection, topological invariants of topological phases of matter in free fermion systems, e.g., topological band insulators, can be directly computed via the properties of band structure. Nevertheless, it is usually difficult to extract topological invariants in strongly-correlated topological phases of matter in which band structure is not well-defined. One typical example is the fractional quantum Hall effect whose low-energy physics is governed by Chern-Simons topological gauge theory and Hall conductivity plateaus involve extremely fruitful physics of strong correlation. In this article, we focus on intrinsic topological order (iTO), symmetry-protected topological phases (SPT), and symmetry-enriched topological phases (SET) in boson and spin systems. Through gauge field-theoretical approach, we review some research progress on these topological phases of matter from the aspects of projective construction, low-energy effective theory and topological response theory.
The rheology property of organogels based on 3D helical nanofilament bnetworks self-assembled by bent-core liquid crystals
Authors: Wang Xing-Zheng , Yang Chen-Jing , Cai Li-Heng , Chen Dong ,   Institute of Process Equipment, College of Energy Engineering, Zhejiang University, Hangzhou 310027, China,   College of Materials Science and Engineering, University of Virginia, Charlottesville 22904, United States of America
Published: December 2020

In the B4 phase of bent-core liquid crystals, smectic layers of tilted achiral bent-core molecules are chiral and polar, which, driven by intra-layer structural mismatch, eventually twist into helical nanofilaments. We design a NOBOW/hexadecane organogel system, which is different from traditional organogel system, and the studied organogels show reversible gel-liquid transitions under temperature cycles. At high temperature, the NOBOW molecules dissolve in hexadecane and the storage modulus and viscous modulus show typical liquid characteristics. At low temperature, the mobility of NOBOW molecules decreases and the storage modulus of the organogels increases as the temperature decreases. We conduct a rheology experiment to systematically investigate the viscoelasticity of the organogel to understand the property of the organogel and develop the application in soft matter. The viscoelastic studies of the organogels reveal that the helical nanofilaments are internally strained and their 3D networks are relatively stiff, which provides an in-depth insight into the properties of the organogels and paves the way for their applications in soft matter.
Surface-textured polymer microspheres generated through interfacial instabilities of microfluidic droplets for cell capture
Authors: Wang Yue-Tong , Shang Luo-Ran , Zhao Yuan-Jin ,   State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China,   Zhongshan-Xuhui Hospital, Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
Published: December 2020

Polymer microparticles with various compositions and morphologies have recently received much attention. Their surface-roughness significantly affects the physical and chemical properties, which especially counts in regulating the interaction between biological materials and living systems. In this paper, we design a polystyrene microsphere with controllable surface textures. At first, a microfluidic device is used to generate droplets with uniform size containing the hydrophobic polymer and a co-surfactant. During the volatilization of the organic solvent, the shrinking droplets appear to be unstable at the interface. Thus, the surface area increases spontaneously, and microspheres with wrinkles on the surface are obtained after being solidified. The results show that tuning the concentration of the co-surfactant and the rate of solvent evaporation can effectively regulate the surface roughness of the microspheres. Circulating tumor cell capture experiments reveal that this textured structure can facilitate the cell adhesion and increase the number of the captured cells. These features indicate that the coarse microspheres possess a promising application prospect in the field of biomedical analysis.
Casimir force
Authors: Miao Bing ,   College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

Casimir force in quantum electrodynamics is the representation of zero point energy of vacuum. Depending on the type of fluctuation medium, generalized Casimir force covers a wide spectrum of topics in physics, such as, quantum, critical, Goldstone mode, and non-equilibrium Casimir force. In general, long range correlated fluctuations and constraints are two conditions for generating the Casimir force. In this paper, through a survey of the development of Casimir physics, we discuss several types of Casimir forces and several regularization methods. We end the paper with an outlook for the further development of Casimir physics in the future.
Electrothermal coupling analysis of three-dimensional integrated microsystem based on dual cell method
Authors: Cao Ming-Peng , Wu Xiao-Peng , Guan Hong-Shan , Shan Guang-Bao , Zhou Bin , Yang Li-Hong , Yang Yin-Tang ,   School of Microelectronics, Xidian University, Xi’an 710071, China,   Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory, Guangzhou 510610, China
Published: December 2020

With the improvement of the integration and power density of three-dimensional integrated microsystem, it is imperative to simultaneously investigate the multi-field coupling analysis of electrical design and thermal management. This paper is to investigate a three-dimensional integrated microprocessor system and realize the rapid electrothermal analysis of the system through an improved dual cell method (DCM). This method decomposes the constitutive matrix into a constant matrix and a temperature-dependent matrix by introducing the coupling of leakage power and material coefficients with temperature. In the calculation, only the temperature-dependent matrix needs to be updated and assembled, which makes the calculation speed faster than the traditional finite element method. The simulation results show that the speed of the proposed algorithm is improved by about 30% compared with that of the traditional finite element method. After considering the thermal coupling factors of material coefficient and leakage power, the hot spot temperature of the system increases by 20.8 K compared with before coupling. Finally, the algorithm proposed in this paper is used to study the layout of three-dimensional integrated microprocessor system. The influence of TSV array conventional layout and centralized layout under the processor core(core-layout) on the hot spot temperature of upper and lower chips are compared, and the influences of uneven power distribution on the two layouts are studied. The results show that compared with the conventional layout of TSV array, the core-layout can reduce the hot spot temperature of processor, but it will aggravate the hot spot problem of DRAM at the same time. And when the power is not evenly distributed on the four cores, the hot spot of DRAM under the core-layout will be more seriously affected. In conclusion, the algorithm model proposed in this paper can quickly analyze the electrothermal coupling problem of 3D integrated microsystem, realize the hot spot prediction of the system, and provide theoretical guidance for designing the chip layout of 3D integrated microsystem.
Experimental study of cavity evolution and deformation during water entering into hyperelastic sphere
Authors: Yang Liu , Sun Tie-Zhi , Wei Ying-Jie , Wang Cong , Li Jia-Chuan , Xia Wei-Xue ,   School of Astronautics, Harbin Institute of Technology, Harbin 150001, China,   School of Naval Architecture, Dalian University of Technology, Dalian 116024, China,   Tianjin Navigation Instrument Research Institute, Tianjin 300131, China
Published: December 2020

Hyperelastic materials, which have strong nonlinear mechanical properties, are commonly used in the engineering field. The application of hyperelastic materials to the water entry problem is a new interdisciplinary research topic. Unlike the water entering into a traditional rigid sphere, the hyperelastic sphere is very easy to deform during water entry. In order to explore the fluid-structure coupling problem with large deformations during water entry, a high-speed camera is used to study the problem of vertical water entering into hyperelastic sphere in this paper. Based on the experimental results, the effects of the material properties and impacting conditions on the cavity flow and sphere deformation behaviors during water entry are compared and analyzed. The experimental results show that the formation of the nested cavity after impacting a free surface of the hyperelastic sphere needs large enough impact conditions and small material shear modulus. The time for the nested cavity to be formed and retained during water entry is related to the material shear modulus and sphere diameter. The sphere displacement and length of cavity formed by the hyperelastic sphere increase with the increase of the impact velocity and material shear modulus, but decrease with the increase of the diameter of the sphere. The increase of the impacting velocity can only aggravate the deformation behaviors of the hyperelastic sphere, but does not affect the formation moment of the nested cavity. In addition, the characteristics for the deformation behaviors of the hyperelastic sphere to vary with the Froude number and the dimensionless ratio of material shear modulus to impacting hydrodynamic pressure are described and studied.
Comparison between optimal configuration algorithms of fiber phased array
Authors: Li Ming-Fei , Yuan Zi-Hao , Liu Yuan-Xing , Deng Yi-Cheng , Wang Xue-Feng ,   Beijing Institute of Aerospace Control Instruments, Beijing 100039, China,   Quantum Engineering Research Center, China Aerospace Science and Technology Corporation, Beijing 100094, China
Published: December 2020

Optical fiber phased array can be used in high-power laser beam combination, lidar and other areas. The configuration of the optical fiber array is different from the microwave phased array, which has periodic problems that affect the energy intensity distribution of the main lobe. Starting from the physical model, in this paper we establish a theoretical model of optical phased array antenna array based on a set of concentric circular ring lattices, and propose a theory of the rapid synthesis of randomly configured interference field strengths through using analytical continuation method and Fourier transform method. The problem of sampling bandwidth and sampling number that should be paid attention to in the numerical simulation of discrete sampling are discussed, and the problem of quickly realizing the numerical simulation of multi-beam interference field is solved. Genetic algorithm and particle swarm algorithm for optimizing the configuration of optical phased array antennas are investigated with different populations. The convergence speeds and optimization efficiencies of the two algorithms are compared and analyzed. It is demonstrated that the peak side-lobe ratio PSR can be achieved to be better than 0.270 by the genetic algorithm optimized configuration array under the real fabricate parameter. The proposed method is expected to be used in the actual optical phased array antenna configuration to guide the optimal design of the antenna with low side lobes, and the proposed model is also expected to provide a certain reference value for the study of optimizing the non-differentiable objective function.
How Pac-Man Eats
Authors: Wardrip-Fruin Noah
Published: December 2020

How the tools and concepts for making games are connected to what games can and do mean; with examples ranging from Papers, Please to Dys4ia.

In How Pac-Man Eats, Noah Wardrip-Fruin considers two questions: What are the fundamental ways that games work? And how can games be about something? Wardrip-Fruin argues that the two issues are related. Bridging formalist and culturally engaged approaches, he shows how the tools and concepts for making games are connected to what games can and do mean.

Wardrip-Fruin proposes that games work at a fundamental level on which their mechanics depend: operational logics. Games are about things because they use play to address topics; they do this through playable models (of which operational logics are the primary building blocks): larger structures used to represent what happens in a game world that relate meaningfully to a theme. Game creators can expand the expressiveness of games, Wardrip-Fruin explains, by expanding an operational logic. Pac-Man can eat, for example, because a game designer expanded the meaning of collision from hitting things to consuming them. Wardrip-Fruin describes strategies game creators use to expand what can be said through games, with examples drawn from indie games, art games, and research games that address themes ranging from border policy to gender transition. These include Papers, Please, which illustrates expansive uses of pattern matching; Prom Week, for which the game's developers created a model of social volition to enable richer relationships between characters; and Dys4ia, which demonstrates a design approach that supports game metaphors of high complexity.
Reckonings
Authors: Chrisomalis Stephen
Published: December 2020

Insights from the history of numerical notation suggest that how humans write numbers is an active choice involving cognitive and social factors.

Over the past 5,000 years, more than 100 methods of numerical notation—distinct ways of writing numbers—have been developed and used by specific communities. Most of these are barely known today; where they are known, they are often derided as cognitively cumbersome and outdated. In Reckonings, Stephen Chrisomalis considers how humans past and present have used numerals, reinterpreting historical and archaeological representations of numerical notation and exploring the implications of why we write numbers with figures rather than words.

Chrisomalis shows that numeration is a social practice. He argues that written numerals are conceptual tools that are transformed to fit the perceived needs of their users, and that the sorts of cognitive processes that affect decision-making around numerical activity are complex and involve social factors. Drawing on the triple meaning of reckon—to think, to calculate, and to judge—as a framing device, Chrisomalis argues that the history of numeral systems is best considered as a cognitive history of language, writing, mathematics, and technology.

Chrisomalis offers seven interlinked essays that are both macro-historical and cross-cultural, with a particular focus, throughout, on Roman numerals. Countering the common narrative that Roman numerals are archaic and clumsy, Chrisomalis presents examples of Roman numeral use in classical, medieval, and early modern contexts. Readers will think more deeply about written numbers as a cognitive technology that each of us uses every single day, and will question the assumption that whatever happened historically was destined to have happened, leading inevitably to the present.
A genome engineering resource to uncover principles of cellular organization and tissue architecture by lipid signaling
Authors: Trivedi Deepti , CM Vinitha , Bisht Karishma , Janardan Vishnu , Pandit Awadhesh , Basak Bishal , H Shwetha , Ramesh Navyashree , Raghu Padinjat
Published: December 2020

Phosphoinositides (PI) are key regulators of cellular organization in eukaryotes and genes that tune PI signaling are implicated in human disease mechanisms. Biochemical analyses and studies in cultured cells have identified a large number of proteins that can mediate PI signaling. However, the role of such proteins in regulating cellular processesin vivoand development in metazoans remains to be understood. Here, we describe a set of CRISPR-based genome engineering tools that allow the manipulation of each of these proteins with spatial and temporal control during metazoan development. We demonstrate the use of these reagents to deplete a set of 103 proteins individually in theDrosophilaeye and identify several new molecules that control eye development. Our work demonstrates the power of this resource in uncovering the molecular basis of tissue homeostasis during normal development and in human disease biology.
Primary and promiscuous functions coexist during evolutionary innovation through whole protein domain acquisitions
Authors: Escudero José Antonio , Nivina Aleksandra , Kemble Harry E , Loot Céline , Tenaillon Olivier , Mazel Didier
Published: December 2020

Molecular examples of evolutionary innovation are scarce and generally involve point mutations. Innovation can occur through larger rearrangements, but here experimental data is extremely limited. Integron integrases innovated from double-strand- toward single-strand-DNA recombination through the acquisition of the I2 α-helix. To investigate how this transition was possible, we have evolved integrase IntI1 to what should correspond to an early innovation state by selecting for its ancestral activity. Using synonymous alleles to enlarge sequence space exploration, we have retrieved 13 mutations affecting both I2 and the multimerization domains of IntI1. We circumvented epistasis constraints among them using a combinatorial library that revealed their individual and collective fitness effects. We obtained up to 104-fold increases in ancestral activity with various asymmetrical trade-offs in single-strand-DNA recombination. We show that high levels of primary and promiscuous functions could have initially coexisted following I2 acquisition, paving the way for a gradual evolution toward innovation.
Changes in Estonian School Calendar Holidays in 1992–2018
Authors:   Estonian Literary Museum, Estonia, Kõiva Mare , Muhu Kristina ,   Department of Folkloristics, Estonian Literary Museum, Centre of Excellence in Estonian Studies
Published: December 2020

The paper compares changes in the celebration of holidays in the period from 1992 to 2018. The data originate from large Estonian children’s lore corpora from 1992, 2007, and 2018. The first collections are preserved at the Estonian Folklore Archives of the Estonian Literary Museum (ELM) in Tartu, Estonia, and the 2018 collection as well as the digitized data of the earlier campaigns are available in the digital archives EFITA – the Research Archives of the Department of Folkloristics of the ELM. The calendar corpus allows us to monitor changes in the structure and essence of folk/ethnographic/local traditions, feasts celebrated at home, church feasts, and public holidays at school. The authors indicate that endeavours to establish national public holidays to accompany traditional agrarian ones began in the early 20th century. During the 20th century, the system of holidays changed three times (1918, 1940, 1991) due to political changes: the establishment of an independent state in Estonia, the loss of independence and continuation as the Estonian Soviet Socialist Republic, and restoration of independence in 1991. In addition to state, church, and folk holidays different ways to introduce novel international holidays (Valentine’s Day, Mother’s Day, Father’s Day, Halloween, Mother Tongue Day), and a search for new forms of celebration were also noteworthy during this period. As students, youngsters participate in the celebrations of their school as well as in the celebrations of public holidays, and at the same time are involved in maintaining their family traditions.
The performance of a modified EWMA control chart for monitoring autocorrelated PM2.5 and carbon monoxide air pollution data
Authors: Supharakonsakun Yadpirun , Areepong Yupaporn , Sukparungsee Saowanit
Published: December 2020

PM2.5 (particulate matter less than or equal to 2.5 micron) is found in the air and comprises dust, dirt, soot, smoke, and liquid droplets. PM2.5 and carbon monoxide emissions can have a negative impact on humans and animals throughout the world. In this paper, we present the performance of a modified exponentially weighted moving average (modified EWMA) control chart to detect small changes when the observations are autocorrelated with exponential white noise through the average run length evaluated (ARLs) by explicit formulas. The accuracy of the solution was verified with a numerical integral equation method. The efficacy of the modified EWMA control chart to monitor PM2.5 and carbon monoxide air pollution data and compare its performance with the standard EWMA control chart. The results suggest that the modified EWMA control chart is far superior to the standard one.
Polyester or epoxy: assessing embedding product efficacy in paleohistological methods
Authors: Heck Christian T. , Volkmann Gwyneth , Woodward Holly N.
Published: December 2020

Histological examination of bone microstructure provides insight into extant and extinct vertebrate physiology. Fossil specimens sampled for histological examination are typically first embedded in an inexpensive polyester resin and then cut into thin sections, mounted on slides, and polished for viewing. Modern undecalcified bone is chemically processed prior to embedding in plastic resin, sectioning, mounting, and polishing. Conversely, small fossil material and modern undecalcified bone are typically embedded in higher priced epoxy resin because these specimen types require final sections near or below 100 µm thick. Anecdotal evidence suggests thin sections made of polyester resin embedded material polished thinner than 100 µm increases likelihood of sample peeling, material loss, and is unsuitable for modern tissue and small fossil material. To test this assertion, a sample of modern bones and fossil bones, teeth, and scales were embedded in either polyester resin or epoxy resin. Embedded specimens were sectioned and mounted following standard published protocol. Thin sections were ground on a lapidary wheel using decreasing grit sizes until tissue microstructure was completely discernible when viewed under a polarizing light microscope. Additionally, eight prepared thin sections (four from polyester resin embedded specimens and four from epoxy resin embedded specimens) were continuously ground on a lapidary wheel using 600 grit carbide paper until peeling occurred or material integrity was lost. Slide thickness when peeling occurred was measured for comparing slide thickness when specimen integrity was lost between the two resin types. Final slide thickness ranged from 38 µm to 247 µm when tissue was identifiable using a polarizing microscope. Finished slide thickness varied between resin types despite similar tissue visibility. However, finished slide thickness appears more dependent on hard tissue composition than resin type. Additionally, we did not find a difference of slide thickness when material was lost between resin types. The results of this preliminary study suggest that polyester resins can be used for embedding undecalcified modern hard tissues and fossilized hard tissues without loss of tissue visibility or material integrity, at least in the short term.
Changes in sprint performance and sagittal plane kinematics after heavy resisted sprint training in professional soccer players
Authors: Lahti Johan , Huuhka Toni , Romero Valentin , Bezodis Ian , Morin Jean-Benoit , Häkkinen Keijo
Published: December 2020

Background

Sprint performance is an essential skill to target within soccer, which can be likely achieved with a variety of methods, including different on-field training options. One such method could be heavy resisted sprint training. However, the effects of such overload on sprint performance and the related kinetic changes are unknown in a professional setting. Another unknown factor is whether violating kinematic specificity via heavy resistance will lead to changes in unloaded sprinting kinematics. We investigated whether heavy resisted sled training (HS) affects sprint performance, kinetics, sagittal plane kinematics, and spatiotemporal parameters in professional male soccer players.

Methods

After familiarization, a nine-week training protocol and a two-week taper was completed with sprint performance and force-velocity (FV) profiles compared before and after. Out of the two recruited homogenous soccer teams (N = 32, age: 24.1 ± 5.1 years: height: 180 ± 10 cm; body-mass: 76.7 ± 7.7 kg, 30-m split-time: 4.63 ± 0.13 s), one was used as a control group continuing training as normal with no systematic acceleration training (CON,N = 13), while the intervention team was matched into two HS subgroups based on their sprint performance. Subgroup one trained with a resistance that induced a 60% velocity decrement from maximal velocity (N = 10, HS60%) and subgroup two used a 50% velocity decrement resistance (N = 9, HS50%) based on individual load-velocity profiles.

Results

Both heavy resistance subgroups improved significantly all 10–30-m split times (p < 0.05,d =  − 1.25; −0.62). Post-hoc analysis showed that HS50% improved significantly more compared to CON in 0–10-m split-time (d = 1.03) and peak power (d = 1.16). Initial maximal theoretical horizontal force capacity (F0) and sprint FV-sprint profile properties showed a significant moderate relationship with F0 adaptation potential (p < 0.05). No significant differences in sprinting kinematics or spatiotemporal variables were observed that remained under the between-session minimal detectable change.

Conclusion

With appropriate coaching, heavy resisted sprint training could be one pragmatic option to assist improvements in sprint performance without adverse changes in sprinting kinematics in professional soccer players. Assessing each player’s initial individual sprint FV-profile may assist in predicting adaptation potential. More studies are needed that compare heavy resisted sprinting in randomized conditions.
Reincorporação da Ética às Políticas Públicas de Turismo
Authors: Tasso João Paulo Faria , Moesch Marutschka Martini , Nóbrega Wilker Ricardo de Mendonça
Published: December 2020

Sob uma ótica global, o fenômeno turístico tem sido caracterizado por uma racionalidade econômica que fortalece a dissociação entre “políticas públicas” e “ética”, ao abdicar de propósitos voltados ao bem comum. Reproduz a lógica finalística de crescimento no fluxo excessivo de turistas e a expansão do consumo, sem um planejamento responsável e sustentável. O objetivo desta pesquisa é compreender em que medida a ética vem sendo contemplada nas políticas públicas nacionais de Turismo, e identificar elementos que possam se tornar premissas e/ou proposições para futuras políticas de mitigação das consequências da pandemia (Covid-19), com vistas ao bem comum e a sustentabilidade. Para tanto, foi realizada uma pesquisa exploratória, com abordagem qualitativa, por meio de entrevistas com 29 pesquisadores de notório saber no campo do Turismo. Resultados apontam que as futuras políticas públicas de Turismo, no combate aos distúrbios do Covid-19, devem considerar, como premissa suprema, o propósito para além de uma base restringida ao progresso econômico dos destinos, mas principalmente direcionado a um processo de desenvolvimento humano e sustentável e de bem estar comum.
Polymerization of Ethylene in the Presence of Various Ligand Organometallic Catalytic Systems
Authors: Zeynab Qanbarli , Akber Khanmetov , Hemide Azizbeyli , Matlab Khamiyev
Published: December 2020

This work presents the results on the preparation of new readily available zirconium-containing arylimine complex catalytic systems and their application together with metallocenes in ethylene polymerization. For this purpose, zirconium complexes with grafted ionic liquid type ligands were synthesized and tested in the ethylene polymerization process. On the other hand, it is known that one of the main industrial catalysts for the polymerization process of ethylene is dicycopentadienyl titanium and zirconium dichloride. Therefore, one of the main objectives of the work is to test the using of the newly synthesized complexes with the industrial Cp2TiCl2 catalyst. The products obtained were identified by various physicochemical methods and it was found that these catalytic systems allow one to control the structure and composition of the products obtained.
Efficacy of Oral Artemisinin and Praziquantel Chemotherapy on Schistosoma mansoni Infected Mice by Means of Parasitological Parameters
Authors: Sulaiman Nassar, Adebayo , Solomon Bakarey, Adeleye , Aderemi Abdulazeez, Abubakar
Published: December 2020

Aim: Praziquantel-based chemotherapy is generally effective in the control of morbidity, decline in the prevalence and intensity of Schistosoma mansoni infections. Nevertheless, the potential emergence of praziquantel resistance in S. mansoni posses danger in the elimination of this neglected tropical disease in Africa. Therefore, this study was designed to evaluate the in-vivo efficacy of Praziquantel and Artemisinin using mice infected with S. Mansoni cercariae.

Methods: Infected mice with S. mansoni were treated with different doses of Artemisinin and Praziquantel from day 42 post infection to assess its efficacy on adult worms and eggs. A 2-day Protocol: artemisinin 400 mg/kg with Praziquantel of 500 mg/kg daily, 4-day protocol: artemisinin 200 mg/kg with praziquantel of 250 mg/kg daily, 6-day protocol: artemisinin 100 mg/kg with praziquantel of 125 mg/kg daily were used. A value of p <0.05 was considered as the level of significance using statistical package for social sciences (SPSS) version 21.

Results: Of the 150 snails collected, 60(40%) were confirmed to be Biomphalaria, while 50(33.3%) and 40(26.3%) were Bulinus and Intercalatum respectively. Highest reduction of 66.3% was found in group II, compared with 58.8% and 56.5% significant reductions in groups I and III, respectively. Also, there were 77.8% and 74.2% significant reductions in eggs per gram of the small intestinal tissue noted in groups I and II respectively as against 63.1% reduction in group III. A significant decline in the percentage of total immature stages of 6.14% in group I was observed when compared to 66.14% in the control. Furthermore, a statistically significant boost of 57.57% was found in the protocol of Artemisinin 100 mg/kg with Praziquantel 125 mg/kg daily (6-day protocol) causing decreases of 43.9% and 42.4% in the total and female worm loads, respectively. The combination decreased intestinal tissue egg loads ranging from 63.1% to 77.8% and liver egg loads ranging from 56.5% to 66.3% rates.

Conclusion: Combined effect of the drugs has confirmed some level of efficacy on experimental S.  Mansoni with significant reduction in tissue egg burden.
A New Flame AAS Application for Magnesium Determination in Solid Pharmaceutical Preparations as an Active Ingredient and an Excipient
Authors: Sbahi Abdullah , Abdelwahed Wassim , Sakur Amir Alhaj
Published: December 2020

Objective: A new application of Atomic Absorption Spectroscopy (AAS) has been carried out to determine magnesium in its solid preparations (effervescent and uncoated compressed tablets) as an active ingredient and/or excipient.

Methodology: The linear range of magnesium was determined. A sample of magnesium effervescent tablets was analyzed. Magnesium stearate concentration was also indirectly determined in commercial paracetamol tablets using two digestion methods. Finally, a sample of drug-free tablets (only contain excipients) was analyzed to study the effect of talc on total magnesium content of the sample.

Results: Linear range was observed in concentrations between 0.08-0.40 ug/mL of magnesium. Effervescent tablets samples were recovered in the range between 98.66-103.00% which indicates that the product meets specifications.  For paracetamol tablets, the content of magnesium stearate was in average of 0.2% and there is no differences between the two digestion methods (t=0.454). Our work on the drug-free sample proved a significant increase of magnesium concentrations in the presence of talc.

Conclusion: The AAS method is a simple and rapid technique that can be employed for the simultaneous estimation of magnesium in in-process and final products analyses.
A Current Review on Analytical Tools for Determination of New Oral Antidiabetic Drugs, Empagliflozin, Linagliptin and Biguanides in Bulk Materials, Pharmaceuticals & Biological Samples
Authors: Baokar S. , Mane K. , Bhujbal A. , Pharande S. , Patil G. , Patil R. , Jain P. , Pandey A.
Published: December 2020

Worldwide the R & D divisions of Pharma industry are actively involved in the development of new therapeutic agents. These agents may be either new entities or partial structural modification of the existing one. The recent FDA statistics represent that the average number of drug filings are increasing every year in the thrust areas like anti-cancer agents, anti-diabetic, antibiotics, cardio-vascular drugs, respiratory drugs etc. Sodium glucose co-transporter-2(SGLT-2) inhibitors, dipeptidyl peptidase-4 (DPP-4) inhibitors and biguanides are effective oral anti-diabetic agents used in treatment of type 2 Diabetes Mellitus. Therefore, the necessity to explore and compare the existing analytical and bioanalytical assays used for determination of such drugs either single or in combination is crucial. Many methods were reported in the literature for the bio-analysis and analysis of four novel gliptins combinations, empagliflozin-linagliptin, empagliflozin-metformin HCl, linagliptin-metformin HCl, empagliflozin-linagliptin-metformin HCl combination with application on Glyxambi®, Synjardy®, Jentadueto®, Trijardy® XR tablets respectively. Furthermore, this review offered an overview of different methods used for determination of every drug alone as empagliflozin from SGLT-2 inhibitors, linagliptin from DPP-4 inhibitors and metformin from biguanides in a tabulated comparative way. Moreover, the current review emphasizes the most common stability indicating assays to be of interest to the analysts in the area of drug control. This review helps in understanding the further need for the development of analytical methods for the estimation of such drugs.
Lithium‐Substituted Tunnel/Spinel Heterostructured Cathode Material for High‐Performance Sodium‐Ion Batteries
Authors: Liang Xinghui , Kim Hun , Jung Hun‐Gi , Sun Yang‐Kook
Published: December 2020

Sodium manganese oxides as promising cathode materials for sodium‐ion batteries (SIBs) have attracted interest owing to their abundant resources and potential low cost. However, their practical application is hindered due to the manganese disproportionation associated with Mn3+, resulting in rapid capacity decline and poor rate capability. Herein, a Li‐substituted, tunnel/spinel heterostructured cathode is successfully synthesized for addressing these limitations. The Li dopant acts as a pillar inhibiting unfavorable multiphase transformation, improving the structural reversibility, and sodium storage performance of the cathode. Meanwhile, the tunnel/spinel heterostructure provides 3D Na+ diffusion channels to effectively enhance the redox reaction kinetics. The optimized [Na0.396Li0.044][Mn0.97Li0.03]O2 composite delivers an excellent rate performance with a reversible capacity of 97.0 mA h g–1 at 15 C, corresponding to 82.5% of the capacity at 0.1 C, and a promising cycling stability over 1200 cycles with remarkable capacity retention of 81.0% at 10 C. Moreover, by combining with hard carbon anodes, the full cell demonstrates a high specific capacity and favorable cyclability. After 200 cycles, the cell provides 105.0 mA h g–1 at 1 C, demonstrating the potential of the cathode for practical applications. This strategy might apply to other sodium‐deficient cathode materials and inform their strategic design.
Non‐Flammable Liquid and Quasi‐Solid Electrolytes toward Highly‐Safe Alkali Metal‐Based Batteries
Authors: Jaumaux Pauline , Wu Junru , Shanmukaraj Devaraj , Wang Yizhou , Zhou Dong , Sun Bing , Kang Feiyu , Li Baohua , Armand Michel , Wang Guoxiu
Published: December 2020

Rechargeable alkali metal (i.e., lithium, sodium, potassium)‐based batteries are considered as vital energy storage technologies in modern society. However, the traditional liquid electrolytes applied in alkali metal‐based batteries mainly consist of thermally unstable salts and highly flammable organic solvents, which trigger numerous accidents related to fire, explosion, and leakage of toxic chemicals. Therefore, exploring non‐flammable electrolytes is of paramount importance for achieving safe batteries. Although replacing traditional liquid electrolytes with all‐solid‐state electrolytes is the ultimate way to solve the above safety issues, developing non‐flammable liquid electrolytes can more directly fulfill the current needs considering the low ionic conductivities and inferior interfacial properties of existing all‐solid‐state electrolytes. Moreover, the electrolyte leakage concern can be further resolved by gelling non‐flammable liquid electrolytes to obtain quasi‐solid electrolytes. Herein, a comprehensive review of the latest progress in emerging non‐flammable liquid electrolytes, including non‐flammable organic liquid electrolytes, aqueous electrolytes, and deep eutectic solvent‐based electrolytes is provided, and systematically introduce their flame‐retardant mechanisms and electrochemical behaviors in alkali metal‐based batteries. Then, the gelation techniques for preparing quasi‐solid electrolytes are also summarized. Finally, the remaining challenges and future perspectives are presented. It is anticipated that this review will promote a safety improvement of alkali metal‐based batteries.
Gate‐Tunable Polar Optical Phonon to Piezoelectric Scattering in Few‐Layer Bi2O2Se for High‐Performance Thermoelectrics
Authors: Yang Fang , Wu Jing , Suwardi Ady , Zhao Yunshan , Liang Boyuan , Jiang Jie , Xu Jianwei , Chi Dongzhi , Hippalgaonkar Kedar , Lu Junpeng , Ni Zhenhua
Published: December 2020

Atomically thin Bi2O2Se has emerged as a new member in 2D materials with ultrahigh carrier mobility and excellent air‐stability, showing great potential for electronics and optoelectronics. In addition, its ferroelectric nature renders an ultralow thermal conductivity, making it a perfect candidate for thermoelectrics. In this work, the thermoelectric performance of 2D Bi2O2Se is investigated over a wide temperature range (20–300 K). A gate‐tunable transition from polar optical phonon (POP) scattering to piezoelectric scattering is observed, which facilitates the capacity of drastic mobility engineering in 2D Bi2O2Se. Consequently, a high power factor of more than 400 µW m−1 K−2 over an unprecedented temperature range (80–200 K) is achieved, corresponding to the persistently high mobility arising from the highly gate‐tunable scattering mechanism. This finding provides a new avenue for maximizing thermoelectric performance by changing the scattering mechanism and carrier mobility over a wide temperature range.
High Efficiency Inverted GaAs and GaInP/GaAs Solar Cells With Strain‐Balanced GaInAs/GaAsP Quantum Wells
Authors: Steiner Myles A. , France Ryan M. , Buencuerpo Jeronimo , Geisz John F. , Nielsen Michael P. , Pusch Andreas , Olavarria Waldo J. , Young Michelle , Ekins‐Daukes Nicholas J.
Published: December 2020

High‐efficiency solar cells are essential for high‐density terrestrial applications, as well as space and potentially vehicle applications. The optimum bandgap for the terrestrial spectrum lies beyond the absorption range of a traditional dual junction GaInP/GaAs cell, with the bottom GaAs cell having higher bandgap energy than necessary. Lower energy bandgaps can be achieved with multiple quantum wells (QWs), but such a pathway requires advanced management of the epitaxial growth conditions in order to be useful. Strain‐balanced GaAsP/GaInAs QWs are incorporated into a single junction GaAs solar cell and a dual junction GaInP/GaAs solar cell, leading to 27.2% efficiency in the single junction device and a one‐sun record 32.9% efficiency in the tandem device. Good carrier collection and low non‐radiative recombination are observed in the cells with up to 80 QWs. The GaAs cells employ a rear‐heterojunction architecture to boost the open‐circuit voltage to over 1.04 V in the quantum well device, despite the large number of QWs.
Dissolving Vanadium into Titanium Nitride Lattice Framework for Rational Polysulfide Regulation in Li–S Batteries
Authors: Shang Chaoqun , Li Gaoran , Wei Benben , Wang Jiayi , Gao Rui , Tian Yuan , Chen Qing , Zhang Yongguang , Shui Lingling , Zhou Guofu , Hu Yongfeng , Chen Zhongwei , Wang Xin
Published: December 2020

Rational regulation of host–guest interactive chemistry is of great significance but has not yet effectively been applied in lithium–sulfur (Li–S) batteries. Herein, a unique titanium vanadium nitride (TVN) solid solution fabric is developed as an ideal platform for fine structure modulation towards efficient and durable sulfur electrochemistry. The dissolution of V into the TiN lattice framework is shown to subtly tailor the coordinative and electronic structures of Ti and V, tuning their respective chemical affinity to sulfur species. Consequently, the optimized Ti–V interplay renders the highest overall polysulfide adsorpabiltiy, and contributes to strong sulfur immobilization and fast reaction kinetics. The resultant Li–S cells realize an outstanding cyclability with high capacity retention of 97.7% after 400 cycles. Moreover, reversible areal capacity over 6.11 mAh cm−2 can be sustained under a high sulfur loading of 6.0 mg cm−2 and a limited electrolyte concentration of 6.5 mL g−1. This work provides a novel strategic perspective for the rational regulation of fine structure towards superior Li–S batteries and beyond.
Autonomous Strategies for Improved Performance and Reliability of Li‐Ion Batteries
Authors: Zhao Lihong , Sottos Nancy R.
Published: December 2020

The battery community has devoted significant effort to improve the performance and reliability of Li‐ion batteries through the development of new materials. The integration of autonomous function provides an alternative strategy to further extend performance. Autonomous material systems mimic the ability of biological systems to self‐protect, sense, regulate, and heal in response to damage and other environmental changes. When incorporated in batteries, these materials enable autonomic restoration of battery performance upon degradation, as well as autonomic shutdown or extinguishment in response to thermal runaway. Successful strategies for improving Li‐ion battery performance include controlled release of microencapsulated functional additives and the integration of self‐healing or adaptive interlayers and binders. These methods have been effective for stabilizing the solid electrolyte interface, preventing battery fires, restoring electrode conductivity, and suppressing Li dendrite growth. Challenges and opportunities exist in the further application of autonomous strategies in the battery environment. A greater variety of encapsulated additives with precise triggered‐release are needed to address specific battery degradation mechanisms. Incorporation of self‐healing polymers in solid‐state batteries facilitates improvement in interfacial and mechanical stability. The integration of autonomous strategies with battery management systems potentially enables enhanced control over multiple battery cycling parameters.