bluuebunny/crossref_metadata_2025 huggingface dataset:
Surgical strategy for patients with late-diagnosed minor form of cleidocranial dysplasia: three cases
Authors: Haese Kévin , Le Toux Guy
Published: December 2019

Introduction: Cleidocranial dysplasia is a genetic disease affecting bone growth. Observations: 3 patients, aged 12, 14, and 15 followed an orthodontic and surgical treatment to solve an eruption issue of the permanent teeth. Temporary teeth were extracted and impacted teeth were progressively exposed by multiple surgeries under local anesthesia. Anchorages were placed on the teeth and a traction started, on incisors and molars first, then on premolars, and finally on canines. The treatments lasted for 6 to 8 years. Comments: These patients presented minor form of cleidocranial dysplasia which only affected the teeth. The difficulty of these cases lied in the lateness of their diagnosis and treatment. Adaptations had to be made to simplify treatment plans (shortened dental arch, premolar extractions, etc.).
Toxoplasma gondiiin beef consumed in France: regional variation in seroprevalence and parasite isolation
Authors: Blaga Radu , Aubert Dominique , Thébault Anne , Perret Catherine , Geers Régine , Thomas Myriam , Alliot Annie , Djokic Vitomir , Ortis Naïma , Halos Lénaïg , Durand Benoît , Mercier Aurélien , Villena Isabelle , Boireau Pascal
Published: December 2019

In France, the consumption of cattle and sheep meat appears to be a risk factor for infection of pregnant women withToxoplasma gondii. Several nation-wide surveys in France have investigated the prevalence ofT. gondiiin sheep and pig meat, but little is known at present about the prevalence of the parasite in beef. The main objective of the present cross-sectional survey was to estimate the seroprevalence ofT. gondiiinfection in beef consumed in France. A secondary objective was to attempt to isolateT. gondiifrom cattle tissues and to study the geographical and age variations of this seroprevalence. The overall estimate of seroprevalence ofT. gondiiin bovine carcasses (n = 2912), for a threshold of 1:6 was 17.38%. A strong age effect was observed (p < 0.0001) with a seroprevalence of 5.34% for calves (<8 months) and 23.12% for adults (>8 months). Seroprevalence estimates given by area of birth and area of slaughtering for adults showed that the areas with the highest seroprevalence were not the same between these two variables. Only two strains, corresponding to genotype II, were isolated from heart samples, indicating that there is a limited risk of human infection withT. gondii, which needs to be correlated with the food habit of consuming raw or undercook (bleuorsaignant) beef. However, new questions have emerged, especially concerning the isolation of parasites from beef and the precise role of bovines, generally described as poor hosts forT. gondii, in human infection.
Using AphasiaBank for Discourse Assessment
Authors: Fromm Davida , Forbes Margaret , Holland Audrey , MacWhinney Brian
Published: December 2019

AphasiaBank is a shared, multimedia database for the study of communication in aphasia. This article describes a variety of discourse measurement tools and teaching resources available at the AphasiaBank website. The discourse measurement tools include main concept analysis, core lexicon checklists, correct information unit computation techniques, and other automated analyses using the CLAN program. These tools can be used to measure a variety of aspects of language production for assessment as well as treatment evaluation and clinical research purposes. Importantly, they are intended to help make the discourse analysis process more efficient and reliable. Teaching resources include an online tutorial on aphasia, videos of typical behaviors seen in aphasia, group treatment videos, classroom activities, tutorial screencasts, and conference posters. These resources can be used for a variety of clinical and educational purposes. The AphasiaBank website is part of the larger TalkBank project which provides many other shared databases and resources that are relevant to professionals interested in communication and communication disorders.
Arcuate Kisspeptin Neurons Coordinate Reproductive Activities with Metabolism
Authors: Rønnekleiv Oline K. , Qiu Jian , Kelly Martin J.
Published: December 2019

Hypothalamic control of fertility is the quintessential homeostatic function. However, fertility is metabolically demanding; so, there must be coordination between energy states and reproductive functions. Because gonadotropin-releasing hormone (GnRH) neurons are devoid of many of the critical metabolic hormone receptors for sensing nutrient levels, it has long been recognized that the sensing of energy stores had to be done by neurons presynaptic to GnRH neurons. Some of the obvious players have been the anorexigenic proopiomelanocortin (POMC) and orexigenic neuropeptide Y (NPY)/agouti-related peptide (AgRP) neurons, both of which are in close apposition to the median eminence, a circumventricular organ. Indeed, POMC and NPY/AgRP neurons are inversely regulated by glucose and metabolic hormones including insulin and leptin. However, their synaptic connections with GnRH neurons are sparse and/or GnRH neurons are lacking the postsynaptic receptors to mediate the appropriate physiological response. Kisspeptin neurons were discovered in the early part of this century and subsequently shown to project to and control GnRH neuronal excitability. In fact, more recently the arcuate kisspeptin neurons have been identified as the command neurons driving pulsatile release of GnRH. Subsequently, it was shown that arcuate kisspeptin neurons express not only steroid hormone receptors but also metabolic hormone receptors such that similar to POMC neurons, they are excited by insulin and leptin. Therefore, based on the premise that arcuate kisspeptin neurons are the key neurons coordinating energy states with reproduction, we will review not only how these vital neurons control pulsatile GnRH release but how they control energy homeostasis through their synaptic connections with POMC and NPY/AgRP neurons and ultimately how E2 can regulate their excitability.
Saphenous Artery Perforator/Propeller Flap in the Reconstruction of Perigenual Soft Tissue Defects
Authors: Balakrishnan T. M. , Narayanan Aishwarya Vadakencherry Lakshmi , Jaganmohan J.
Published: December 2019

Introduction In this article, we investigate the saphenous artery perforator propeller flap for the reconstruction of perigenual defects. We describe the anatomy of the saphenous artery and the method of raising a perforator propeller flap based on our study and early clinical experience.

Aim To assess the effectiveness of the saphenous artery perforator propeller flap in the reconstruction of perigenual defects.

Materials and Methods A preliminary cadaver dissection and injection study was conducted to discern the anatomical details of the perforator system of the saphenous vessel in 35 cadaveric specimens in 18 fresh cadavers. From March 2016 to March 2018, 16 clinical cases (5 females and 11 males, in the average age group of 33.5 years) with perigenual defects were reconstructed with saphenous artery perforator propeller flap. They were followed up for an average period of 12.5 months.

Results Cadaver study established anterior sartorial perforators as the dominant system of the saphenous vessel and brought to the forefront the type 2 blood supply of the saphenous nerve. All patients had well-settled flaps at the end of the follow-up period, with good return of knee function.

Conclusion Saphenous artery perforator propeller flap is a viable option for the reconstruction of defects around the knee joint.

Level of Evidence Type V, therapeutic study.
A Compendium of Core Lexicon Checklists
Authors: Dalton Sarah Grace Hudspeth , Kim Hana , Richardson Jessica D. , Wright Heather Harris
Published: December 2019

Core Lexicon (CoreLex) is a relatively new approach assessing lexical use in discourse. CoreLex examines the specific lexical items used to tell a story, or how typical lexical items are compared with a normative sample. This method has great potential for clinical utilization because CoreLex measures are fast, easy to administer, and correlate with microlinguistic and macrolinguistic discourse measures. The purpose of this article is to provide clinicians with a centralized resource for currently available CoreLex checklists, including information regarding development, norms, and guidelines for use.
Efficacy of Group Conversation Intervention in Individuals with Severe Profiles of Aphasia
Authors: Hoover Elizabeth , McFee Alexandra , DeDe Gayle
Published: December 2019

An estimated 390,000 to 520,000 individuals with severe aphasia (IWSA) currently live in the United States. IWSA experience profound social isolation, which is associated with a wide range of negative health outcomes, including mortality. Treatments for severe aphasia frequently focus on compensatory communication approaches or a discrete communication act rather than on participation-based treatment. The purpose of this study was to determine whether IWSA demonstrated improved performance on standardized language measures, patient-reported outcome measures, and connected speech samples as a result of client-centered conversation group treatment. Results of assessments conducted at pretreatment, posttreatment, and maintenance intervals were variable across participants. All participants demonstrated improvement in at least one of the outcome measures considered. Importantly, none of these measures fully captured how IWSA were able to convey their thoughts in supported conversation. The results lend support for the use of conversation treatment for, and for further study in, this subpopulation of individuals with aphasia.
Combination of iterated cubature Kalman filter and neural networks for GPS/INS during GPS outages
Authors: Liu Fengyu , Sun Xiaohong , Xiong Yufeng , Huang Haoqian , Guo Xiaoting , Zhang Yu , Shen Chong
Published: December 2019

To improve the performance of the Global Positioning System/Inertial Navigation System (GPS/INS) integrated navigation system, current research studies merely combine neural networks with nonlinear filter methods. Few studies focus on how to optimize the parameters of the neural network and how to further improve the small error accumulated into the next filter step due to the imprecise design of the filter when setting the initial parameters in the GPS/INS integrated system. In this article, a dual optimization method consisting of an iterated cubature Kalman filter-Feedforward Neural Network (ICKF-FNN) and a radial basis function-cubature Kalman filter (RBF-CKF) is proposed to compensate the position and velocity errors of the integrated system during GPS outages. The prominent advantages of the proposed method include the following. (i) The ICKF is designed to optimize the parameters of the introduced FNN adaptively and obtain an appropriate internal structure when GPS is available, which improves the accuracy of the training model. (ii) The RBF establishes the relationship between filter parameters and the optimal estimation errors, reducing the errors caused by inaccurate predicted observation during GPS outages. (iii) The proposed dual optimization method takes advantages over other combination algorithms under different moving conditions or even during long period of GPS outages, which shows its great stability. Experimental results show that the root mean squared error of the east position is reduced by 85.79% to 3.2187 m using the proposed strategy during turning movement and the east velocity error accumulation rate decreases by 92.69% during the long straight movement of 250 s. These results are from offline processing.
Web-drive based source measure unit for automated evaluations of ionic liquid-gated MoS2 transistors
Authors: Park So Jeong , Jeon Dae-Young , Moon Young-Sun , Park Il-Hoo , Kim Gyu-Tae
Published: December 2019

For reliable characterization of two-dimensional semiconducting devices and continuous monitoring in toxic environments, construction of an electrical characterization-based massive database using a portable source measure unit (SMU) with a WiFi connection is desirable. The web-drive based SMU using a microcontroller developed here exhibits superior voltage source performance (∼1 mV) and voltage/current measurement (∼0.15 mV/∼1 nA) capabilities, with automatic construction of a measurement database for online storage using web-drive based software, which can be applied for reliable electrical characterization. Electrical characterization of ionic liquid-gated MoS2 transistors was achieved with the designed SMU and showed results comparable with those obtained using a commercial semiconductor characterization system. Ionic liquid-gated transistors only require a small gate bias (∼1.5 V) for on-state operation because of the high gate capacitance originating from the thin dielectric layer constructed of an electrical double layer, which makes the device a promising candidate for low power consumption applications. Finally, several electrical parameters of the ionic liquid-gated transistor were extracted from the datasets and uploaded to the web-drive.
Characterization of the fast ionization wave induced by a CO2 laser pulse in argon
Authors: Shimamura Kohei , Yokota Ippei , Yokota Shigeru
Published: December 2019

Fast ionization wave (FIW), a postbreakdown phenomenon of laser-induced plasma, is observed for a laser intensity of 1011–1013 W/m2 using the CO2 laser pulse in the atmospheric pressure condition. FIW is distinguishable as “overdriven detonation” according to Raizer's Chapmann-Jouguet detonation theory because FIW is known as the type of laser-absorption wave that has a higher propagation velocity than the laser-supported detonation wave (LSDW). Some reports have described the expansion of FIW using a solid-state laser. Nevertheless, the threshold phenomena between FIW and LSDW are not fundamentally understood. This study used the high-speed visualization and optical emission spectroscopy to investigate the transition of the laser-absorption wave in argon gaseous form. To elucidate the physics of the transition threshold, a 5 J CO2 pulse laser, an Echelle spectrometer, and an intensified CCD camera are used for the quantitative investigation of the plasma temperature and density. Results demonstrate that the FIW front had an electron temperature of 0.7 eV and an electron number density of 2.5 × 1023 m−3. At the FIW–LSDW transition, the electron temperature increased by 1 eV, and the density decreased by 2.2 × 1023 m−3. Besides, the transition threshold and the existence of local-thermodynamic equilibrium were evaluated based on the electron temperature, and the density was obtained from the spectroscopic experiments.
Comparative study of Au and Ni/Au gated AlGaN/GaN high electron mobility transistors
Authors: Visvkarma Ajay Kumar , Sharma Chandan , Laishram Robert , Kapoor Sonalee , Rawal D. S. , Vinayak Seema , Saxena Manoj
Published: December 2019

This paper presents the electrical comparison of Au and Ni/Au gated HEMT devices and diodes. Au Schottky diodes on an AlGaN/GaN heterostructure exhibit better electrical performance in comparison to conventional Ni/Au diodes with an improved Schottky barrier height (SBH) and lower reverse leakage current. The SBH extracted from I-V for Au and Ni/Au is 1.29 eV and 0.74 eV, respectively. Au Schottky contacts on GaN have a better ideality factor of 1.55 than Ni, which is 1.61. Capacitance-voltage measurement revealed a positive shift in threshold voltage in the case of Au diodes with a reduced capacitance value with respect to Ni/Au diodes. This decrease in threshold and capacitance indicates a decrease in the 2DEG carrier concentration. The decrease in the 2DEG carrier concentration is consistent with three terminal device measurements. Despite a small decrease in drain current (8%), the Au gated HEMT devices have shown an improved subthreshold slope (13%) and nearly 4 order improvement in the ION/IOFF ratio than Ni/Au gated HEMTs. Pulse IV characterization has indicated that gate lag and drain lag have no major changes with respect to gate metal, whereas current collapse increases for high work function metals.
Resistive gas sensors based on metal-oxide nanowires
Authors: Mirzaei Ali , Lee Jae-Hyoung , Majhi Sanjit Manohar , Weber Matthieu , Bechelany Mikhael , Kim Hyoun Woo , Kim Sang Sub
Published: December 2019

Gas sensors are indispensable for detecting harmful gases in the environment. The morphology of a gas sensor significantly affects its sensing performance. Among the various morphologies, one-dimensional nanowires (NWs) have numerous advantages, such as high surface area, small dimensions, high charge-carrier concentrations, facile synthesis, high crystallinity, and stability. These excellent properties make NWs promising for gas sensing. Resistive-type metal oxide-based gas sensors are widely used for monitoring various toxic gases and volatile organic compounds. In this tutorial, the synthesis of metal oxide NWs, the fabrication of gas sensors, and their sensing mechanisms are discussed. Different types of NW-based gas sensors, such as single NWs, branched NWs, noble metal-functionalized NWs, heterojunction NWs, self-heating NWs, ultraviolet-activated NWs, core–shell NWs, and electronic-nose-based NWs, are comprehensively presented. Finally, we discuss future directions with regard to the improvement and potential of these NW gas sensors. This tutorial aims to provide an overview of the fundamental principle and state-of-the-art technology, which is useful for researchers and students working in the field of resistive-type NW-based gas sensors.
Large scale dynamics of a high Reynolds number axisymmetric separating/reattaching flow
Authors: Pain R. , Weiss P.-E. , Deck S. , Robinet J.-C.
Published: December 2019

A numerical study is conducted to unveil the large scale dynamics of a high Reynolds number axisymmetric separating/reattaching flow at M∞ = 0.7. The numerical simulation allows us to acquire a high rate sampled unsteady volumetric dataset. This huge amount of spatial and temporal information is exploited in the Fourier space to visualize for the first time in physical space and at such a high Reynolds number (ReD = 1.2 × 106) the statistical signature of the helical structure related to the antisymmetric mode (m = 1) at StD = 0.18. The main hydrodynamic mechanisms are identified through the spatial distribution of the most energetic frequencies, i.e., StD = 0.18 and StD ≥ 3.0 corresponding to the vortex-shedding and Kelvin-Helmholtz instability phenomena, respectively. In particular, the dynamics related to the dimensionless shedding frequency is shown to become dominant for 0.35 ≤ x/D ≤ 0.75 in the whole radial direction as it passes through the shear layer. The spatial distribution of the coherence function for the most significant modes as well as a three-dimensional Fourier decomposition suggests the global features of the flow mechanisms. More specifically, the novelty of this study lies in the evidence of the flow dynamics through the use of cross-correlation maps plotted with a frequency selection guided by the characteristic Strouhal number formerly identified in a local manner in the flow field or at the wall. Moreover and for the first time, the understanding of the scales at stake is supported both by a Fourier analysis and a dynamic mode decomposition in the complete three-dimensional space surrounding the afterbody zone.
Field-cooled magnetization of Y-Ba-Cu-O superconducting bulk pair reinforced by full metal encapsulation under high magnetic fields up to 22 T
Authors: Naito Tomoyuki , Fujishiro Hiroyuki , Awaji Satoshi
Published: December 2019

We report on the field-cooled magnetization (FCM) process under magnetic fields of up to 22 T for the stacked Y-Ba-Cu-O (YBCO) bulk pair reinforced by a stainless steel (SUS316) container. On the basis of the numerically simulated mechanical stress in a bulk during FCM, the SUS316 container was designed by the numerical simulation to offer the sufficient hoop stress tolerance to the bulk trapping the magnetic field of 20 T. As a result, we obtained successfully the trapped field, BT, of 15.1 T by FCM from 18 T at 28 K at the center of the YBCO bulk pair. However, the extremely large-scale vortex jumps and large temperature rise occurred suddenly during FCM from a higher field of 22 T at a lower temperature of 23 K, and then a small crack was confirmed at the periphery of “both” YBCO bulks from the distorted contour maps of BT. The simultaneous break of both YBCO bulks probably in spite of sufficient mechanical reinforcement led us to conclude that the thermal instability triggered off the large-scale vortex jumps and large heat generation. The stress concentration induced thermally at the hot spot brought about the cracking.
Two-dimensional particle simulation on the behavior of multi-charged copper ions in the cathode spot of a pulsed vacuum arc discharge
Authors: Yang Wei , Zhou Qianhong , Sun Qiang , Dong Zhiwei
Published: December 2019

The behavior of multicharged ions in the cathode spot of pulsed copper vacuum arc is studied by the 2D3V electrostatic Particle-In-Cell Direct Simulation Monte Carlo method. This method tracks the position and velocity of electrons, neutrals, and copper ions charged from +1 to +4 simultaneously, which couples with external circuit physics as well as heat conduction at the cathode. The general thermofield electron emission developed in recent years is used in the vacuum arc simulation. The simulation starts from complete vacuum until the arc current reaches the steady state at about 3 A limited by the external circuit, and the arc voltage is between 20 and 30 V. During the discharge, the cathode temperature increases from room temperature to around 8000 K. The breakdown process is visualized by the distribution of ion density at different stages of arc discharge: from a small volume of cathode spot to a conductive current path between electrode gaps. The vacuum arc plasma is found to be highly ionized, with an average charge state slightly above two and electron density on the order of 1020 cm−3. The positively charged ions move in the direction from the cathode to anode, which is opposite to the direction of the applied external field. Ion energies at the steady state increase from 20 to 200 eV when charge states increase from +1 to +4. This indicates that the electrostatic acceleration of ions is caused by a dynamic space-charge field in the breakdown process of pulsed vacuum arc discharge.
Coordination changes in liquid tin under shock compression determined using in situ femtosecond x-ray diffraction
Authors: Briggs R. , Gorman M. G. , Zhang S. , McGonegle D. , Coleman A. L. , Coppari F. , Morales-Silva M. A. , Smith R. F. , Wicks J. K. , Bolme C. A. , Gleason A. E. , Cunningham E. , Lee H. J. , Nagler B. , McMahon M. I. , Eggert J. H. , Fratanduono D. E.
Published: December 2019

Little is known regarding the liquid structure of materials compressed to extreme conditions, and even less is known about liquid structures undergoing rapid compression on nanosecond timescales. Here, we report on liquid structure factor and radial distribution function measurements of tin shock compressed to 84(19) GPa. High-quality, femtosecond x-ray diffraction measurements at the Linac Coherent Light Source were used to extract the liquid diffuse scattering signal. From the radial distribution function, we find that the structural evolution of the liquid with increasing pressure mimics the evolution of the solid phase. With increasing pressure, we find that the liquid structure evolves from a complex structure, with a low coordination number, to a simple liquid structure with a coordination number of ∼12. We provide a pathway for future experiments to study liquids at elevated pressures using high-energy lasers to shock compress materials beyond the reach of static diamond anvil cell techniques.
Electron extraction enhancement via the magnetic field in a miniature microwave discharge neutralizer
Authors: Sato Yosuke , Koizumi Hiroyuki , Nakano Masakatsu , Takao Yoshinori
Published: December 2019

This study analyzes the dependence of electron extraction efficiency, which is defined as the ratio of the extracted electron current to the generated electron current, on the orifice shapes and magnetic fields of a miniature microwave discharge xenon neutralizer via three-dimensional particle-in-cell simulations with Monte Carlo collisions (PIC–MCCs). The PIC–MCC simulation results show that the orifice shapes do not significantly affect the discharge characteristics or the electron extraction efficiency. However, the efficiency achieves a 1.5-times higher value in a new magnetic field configuration, referred to as MF-2, where the magnetic field lines pass through nearly the entire area of the orifices. This improvement is attributed to the reduction in the electron backflow and the electron loss toward both the downstream inside surface and the outside wall of the discharge chamber. In addition, there are relatively small plasma fluctuations in the discharge chamber for MF-2 due to its low Bohm diffusion coefficient, where no rotating spokes, which are often seen in other E × B devices, are observed. As a result, the electron loss toward the downstream surface inside the discharge chamber is reduced, and this decrease in the electron loss also contributes to the increase in the extraction efficiency.
Enhanced terahertz radiation of photoconductive antenna fabricated on GaAs-on-sapphire
Authors: Zhang Jitao , Tuo Mingguang , Gehl Michael , Gibson Ricky , Liang Min , Xin Hao
Published: December 2019

The terahertz (THz) radiation properties of a photoconductive antenna (PCA) fabricated on a GaAs-on-sapphire (GoS) substrate are reported at sub-THz band. The GaAs layer with a thickness of approximately 1 µm was directly deposited on a sapphire wafer by means of molecular beam epitaxy. A butterfly-shaped antenna structure was then fabricated on the GoS substrate by photolithography, and the device was tested as the emitter of an in-house built THz time-domain spectrometer. The performance of this antenna was compared with a commercial one, which had an identical antenna structure but was fabricated on low-temperature-grown GaAs (LT-GaAs). The results showed that the GoS-based PCA radiated an enhanced THz field, which could be as much as 1.9 times that of the LT-GaAs-based PCA, indicating that GoS could be a promising photoconductive material. In addition, the optical transparency of the sapphire substrate allows the device to be illuminated from the backside, which is crucial for THz near-field imaging applications where the sample is usually in close proximity to the front surface of the PCA device.
Facile synthesis of manganese (II)-doped ZnSe nanocrystals with controlled dimensionality
Authors: Yu Jung Ho , Kim Junhee , Hyeon Taeghwan , Yang Jiwoong
Published: December 2019

Doping is one of the key technologies in modern semiconductor science and industry. However, the synthetic control of doped nanocrystals is difficult to achieve. Here, we report the facile synthesis of manganese (II) doped ZnSe nanocrystals with controlled dimensionality. A strong Lewis acid-base reaction using air-stable and environmentally friendly metal chlorides as precursors can readily produce a large amount of quantum-confined ZnSe:Mn2+ nanocrystals. A combination of primary and secondary amines is used to control the synthetic chemistry, which enables the shape of the doped nanocrystals to be controlled. The final doping concentration of the products can be finely tunable, which is critical for carrier relaxation dynamics. It turns out that the threshold doping level for the maximum photoluminescence intensity of doped nanocrystals highly depends on their shape. Furthermore, this simple synthetic method is extendable to obtain various Mn2+-doped II–VI semiconductor nanocrystals such as CdS:Mn2+ and ZnS:Mn2+. Our study will facilitate the fundamental understanding of the doped semiconductor nanocrystals with different shapes, which is potentially useful for a wide range of applications such as lighting, photocatalysis, and bioimaging.
High figure-of-merit NEMS thermal detectors based on 50-nm thick AlN nano-plate resonators
Authors: Qian Zhenyun , Rajaram Vageeswar , Kang Sungho , Rinaldi Matteo
Published: December 2019

This paper reports on the demonstration of ultrafast (thermal time constant, τ ∼ 166 μs) and high resolution (noise equivalent power, NEP ∼ 549 pW/Hz1/2) thermal detectors based on high quality factor 50-nm thick aluminum nitride (AlN) piezoelectric resonant nanoplates. Here we show that by employing nanoscale (30 nm) aluminum anchors, both high thermal resistance (Rth ∼ 1.1 × 106 K/W) and high quality factor (Q ∼ 1000) can be achieved in greatly scaled AlN nanoplate resonators. Furthermore, the absorptance of such ultrathin AlN resonators was characterized, in mid-wavelength infrared region showing an average absorptance of ∼36% from 2.75 μm to 6.25 μm. These unique features were exploited for the experimental demonstration of AlN NEMS resonant thermal detectors with greatly reduced thermal capacitance and over doubled figure of merit [FoM = 1/(NEP × τ)] compared to what was previously achieved by the same technology.
Light-driven motion of self-propelled porous Janus particles
Authors: Feldmann David , Arya Pooja , Lomadze Nino , Kopyshev Alexey , Santer Svetlana
Published: December 2019

We introduce a versatile mechanism of light-driven self-propelled motion applied to porous Janus-type particles. The mechanism is based on the generation of local light-driven diffusio-osmotic (l-LDDO) flow around each single porous particle subjected to suitable irradiation conditions. The photosensitivity is introduced by a cationic azobenzene containing surfactant, which undergoes a photoisomerization reaction from a more hydrophobic trans-state to a rather hydrophilic cis-state under illumination with light. The negatively charged porous silica particles are dispersed in a corresponding aqueous solution and absorb molecules in their trans-state but expel them in their cis-state. During illumination with blue light triggering both trans-cis and cis-trans isomerization at the same time, the colloids start to move due to the generation of a steady-state diffusive flow of cis-isomers out of and trans-isomers into the particle. This is because a hemi-spherical metal cap partially sealing the colloid breaks the symmetry of the otherwise radially directed local flow around the particle, leading to self-propelled motion. Janus particles exhibit superdiffusive motion with a velocity of ∼0.5 μm/s and a persistence length of ca. 50 μm, confined to microchannels the direction can be maintained up to 300 μm before rotational diffusion reverts it. Particles forming dimers of different shapes can be made to travel along circular trajectories. The unique feature of this mechanism is that the strength of self-propulsion can be tuned by convenient external optical stimuli (intensity and irradiation wavelength) such that a broad variety of experimental situations can be realized in a spatiotemporal way and in situ.
Large-Z limit in atoms and solids from first principles
Authors: Lehtomäki Jouko , Lopez-Acevedo Olga
Published: December 2019

We present density functional theory (DFT) calculations of atomic ionization potentials and lattice constants of simple solids from low atomic numbers Z to the large-Z limit. We compare different kinetic energy functional approximations [Kohn-Sham (KS) vs simple orbital-free functionals] and, in the case of orbital free, also different methods for including the nuclear potential (all-electron with the projector augmented wave method vs local pseudopotentials). For both ionization potentials and lattice constants, all-electron orbital-free DFT does yield the general trend of KS DFT for moderate values of the atomic number Z. For large values of Z, all-electron orbital-free DFT deviates from the KS DFT results. Local pseudopotentials give a better qualitative description by adding shell oscillations to the orbital-free DFT model. We show that both all-electron orbital-free DFT and KS DFT have a finite value for nonrelativistic lattice constants in the large-Z limit.
Evidence of information limitations in coarse-grained models
Authors: Khot Aditi , Shiring Stephen B. , Savoie Brett M.
Published: December 2019

Developing accurate coarse-grained (CG) models is critical for addressing long time and length scale phenomena with molecular simulations. Here, we distinguish and quantify two sources of error that are relevant to CG models in order to guide further methods development: “representability” errors, which result from the finite basis associated with the chosen functional form of the CG model and mapping operator, and “information” errors, which result from the limited kind and quantity of data supplied to the CG parameterization algorithm. We have performed a systematic investigation of these errors by generating all possible CG models of three liquids (butane, 1-butanol, and 1,3-propanediol) that conserve a set of chemically motivated locality and topology relationships. In turn, standard algorithms (iterative Boltzmann inversion, IBI, and multiscale coarse-graining, MSCG) were used to parameterize the models and the CG predictions were compared with atomistic results. For off-target properties, we observe a strong correlation between the accuracy and the resolution of the CG model, which suggests that the approximations represented by MSCG and IBI deteriorate with decreasing resolution. Conversely, on-target properties exhibit an extremely weak resolution dependence that suggests a limited role of representability errors in model accuracy. Taken together, these results suggest that simple CG models are capable of utilizing more information than is provided by standard parameterization algorithms, and that model accuracy can be improved by algorithm development rather than resorting to more complicated CG models.
Selective separating and assembling motion control for delivery and retrieval of an untethered magnetic robot in human blood vessels
Authors: Park J. , Lee W. , Kim J. , Jung E. , Kim N. , Jang G.
Published: December 2019

We developed an integrated magnetic robot (IMR) that can selectively separate and assemble tethered and untethered magnetic robots. The proposed IMR is composed of a flexible-legged untethered magnetic robot (FLUMR) and a delivery catheter. Assembled magnets (AMs) with zero net magnetic moment are placed at the distal tip of the catheter and the rear part of the FLUMR. A selective separating and assembling (SSA) mechanism was proposed that can control the separating and assembling motion by an external magnetic field (EMF) to generate relative rotational movements between the catheter and FLUMR by selectively producing the attractive and repulsive forces between AMs. Finally, the IMR was prototyped to verify the SSA mechanism, and the separation, mobility, drilling, and retrieval of the developed IMR using SSA mechanism was verified in in vitro experiments.
Turbulent drag reduction by polymer additives: Fundamentals and recent advances
Authors: Xi Li
Published: December 2019

A small amount of polymer additives can cause substantial reduction in the energy dissipation and friction loss of turbulent flow. The problem of polymer-induced drag reduction has attracted continuous attention over the seven decades since its discovery. However, changes in research paradigm and perspectives have triggered a wave of new advancements in the past decade. This review attempts to bring researchers of all levels, from beginners to experts, to the forefront of this area. It starts with a comprehensive coverage of fundamental knowledge and classical findings and theories. It then highlights several recent developments that bring fresh insights into long-standing problems. Open questions and ongoing debates are also discussed.
Managing hysteresis of Gd5Si2Ge2 by magnetic field cycling
Authors: Biswas Anis , Mudryk Yaroslav , Pathak Arjun K. , Zhou Lin , Pecharsky Vitalij K.
Published: December 2019

The influence of magnetic field cycling through the first-order magnetostructural transformation on the magnetic and magnetocaloric properties, as well as hysteresis of polycrystalline Gd5Si2Ge2, has been studied using magnetometry. The cycling has a minimal effect on the magnetic field-induced entropy change and the phase transformation temperature of the material. On the other hand, magnetic hysteresis decreases by 30% after approximately ten cycles and remains low unless the sample is moved far into the paramagnetic regime. Factors playing a role in the history dependence of hysteresis have been discussed.
Magnetic properties and hyperthermia behavior of iron oxide nanoparticle clusters
Authors: Pourmiri Shirin , Tzitzios Vasileios , Hadjipanayis George C. , Meneses Brassea Bianca P. , El-Gendy Ahmed A.
Published: December 2019

In this study, Iron Oxide nanoparticle clusters have been synthesized utilizing individual Fe3O4 nanoparticles with different sizes as building blocks. The synthesis was accomplished by encapsulation of the individual Fe3O4 nanoparticles in an oil in water emulsion via hydrophobic interactions between cetyltrimethylammonium bromide (CTAB) and the nanoparticle’s surface aliphatic capping agents. It has been observed that the time, temperature and CTAB concentration were three crucial factors for controlling the size, shape and collective behavior of the clusters. Powder X-Ray Diffraction study shows that both individual Fe3O4 and the corresponded nanoparticle clusters have the Fe3O4 cubic spinel structure. Dynamic Light Scattering (DLS) shows that the hydrodynamic diameter of cluster is in the range of 100 to 200 nm. Transmission electron microscopy (TEM) images illustrate that different sizes of clusters can be effectively synthesized by using different concentration of CTAB and the results are consistent with the DLS values. Magnetic measurements show that the saturation magnetization of clusters can be changed from 56.7 emu/g to 70.1 emu/g by just changing the size of primary individual nanoparticles from 7.1 nm to 11.5 nm. Also, the blocking temperatures for Fe3O4 clusters were increased to higher temperatures which confirms the stronger collective behavior in the case of larger nanoparticles. The magnetic hyperthermia behavior of the clusters has also been studied, and the data shows that the Specific Absorption Rate (SAR) values are increased by both the clustering and the size of the primary nanoparticles.
Towards the crystal structure of thymine: An intermolecular force field development and parallel global cluster optimizations
Authors: Tekin Adem
Published: December 2019

A new ab initio potential for the thymine dimer has been developed by using a combination of density functional theory and symmetry-adapted perturbation theory (DFT-SAPT). It has been shown that DFT-SAPT is in very good agreement with the reference CCSD(T) calculations performed for the hydrogen-bonded and stacked thymine dimers. Parallel global cluster optimizations have been carried out employing the new force field from the dimer to n = 50. It has been observed that the resulting cluster structures tend to form the building blocks of the crystal structure of thymine. This study therefore highlights the importance of dimer potentials to gain insights about the crystal structures.
Ion beam generation from a protic ionic liquid source with an externally wetted tungsten needle
Authors: Fujiwara Yukio , Saito Naoaki
Published: December 2019

Ionic liquid ion sources (ILISs) are similar to liquid metal ion sources and use ionic liquids (i.e., room temperature molten salts) instead of liquid metals. Aprotic ionic liquids have been used in most cases, whereas protic ion liquids have hardly been used thus far. In this study, propylammonium nitrate (PAN), which is a protic ionic liquid, was tested as the liquid material for an ILIS. Beam generation was investigated in DC operation using a tungsten needle externally wetted with PAN. Experimental results showed that a stable ion beam was generated without special measures and that the ion beam contained cluster ions with m/z values on the order of 103. Additionally, electrochemical experiments were performed in vacuum to investigate electrochemical reactions involved in beam generation. Residual gas analysis revealed that H2O and O2 were electrochemically produced at a tungsten electrode immersed in PAN. These products will probably result from electrochemical reactions of water in PAN because protic ionic liquids contain a small amount of water even in vacuum. The stability of the ion beam can be explained by the effect of water in PAN.
Enhanced triplet state generation through radical pair intermediates in BODIPY-quantum dot complexes
Authors: Jin Tao , Uhlikova Natalie , Xu Zihao , Zhu Yifan , Huang Yiming , Egap Eilaf , Lian Tianquan
Published: December 2019

Generation of triplet excited states through radical pair intermediates has been extensively studied in molecular complexes. Similar schemes remain rare in hybrid structures of quantum dot-organic molecules, despite intense recent interest of quantum dot sensitized triplet excited state generation. Herein, we demonstrate that the efficiency of the intersystem crossing from the singlet to the triplet state in boron dipyrromethene (BODIPY) can be enhanced in CdSe quantum dot-BODIPY complexes through a radical pair intermediate state consisting of an unpaired electron in the quantum dot conduction band and that in oxidized BODIPY. By transient absorption spectroscopy, we show that the excitation of BODIPY with 650 nm light leads to the formation of a charge separated state by electron transfer from BODIPY to CdSe (with a time constant of 6.33 ± 1.13 ns), competing with internal conversion to the ground state within BODIPY, and the radical pair state decays subsequently by back charge recombination to generate a triplet excited state (with a time constant of 158 ± 28 ns) or the ground state of BODIPY. The overall quantum efficiency of BODIPY triplet excited state generation was determined to be (27.2 ± 3.0)%. The findings of efficient triplet state formation and intermediate radical pair states in this hybrid system suggest that quantum dot-molecule complexes may be a promising platform for spintronics applications.
Dynamic and energy analysis of coalescence-induced self-propelled jumping of binary unequal-sized droplets
Authors: Wang Yuhang , Ming Pingjian
Published: December 2019

The coalescence-induced self-propelled droplet jumping on superhydrophobic surfaces has a large number of potential applications such as enhancement of condensation heat transfer, self-cleaning, and anti-icing, which becomes a current hotspot. At present, most of the research studies focus on the self-propelled jumping of two identical droplets; however, the jumping induced by unequal-sized droplets is much closer to actuality. In this paper, the coalescence-induced self-propelled jumping of binary unequal-sized droplets is simulated and all energy terms are studied. The normalized liquid bridge width induced by unequal-sized droplets is a function of the square root of the normalized time, and the maximum jumping velocity is a function of the radius ratio as well. The maximum jumping velocity descends with the decrease in the radius ratio and contact angle, and the critical radius ratio shows an upward trend with the decrease in the contact angle. Furthermore, all energy terms decline with the decrease in the radius ratio. The effective energy conversion rate of binary equal-sized jumping is very low, less than 3% in our results. This rate of binary unequal-sized jumping further reduces due to the existence of asymmetric flow. This work helps for a better understanding of the characteristics of coalescence-induced self-propelled droplet jumping.
Fluid properties have large effects on droplet dynamics under air shear flow
Authors: Bandari Anashe
Published: December 2019

A study on how viscosity and surface tension impact droplet deformation reveals three different behavior regimes.
Low root PIP1-1 and PIP2 aquaporins expression could be related to reduced hydration in ‘Rangpur’ lime plants exposed to aluminium
Authors: Cavalheiro Mariana F. , Gavassi Marina A. , Silva Giselle S. , Nogueira Matheus A. , Silva Carolina M. S. , Domingues Douglas S. , Habermann Gustavo
Published: December 2019

In acidic soils, aluminium (Al) occurs as Al3+, which is phytotoxic. One of the most conspicuous symptoms of Al toxicity is the root growth inhibition, which can lead to low water uptake and consequent reduction in leaf hydration and gas exchange. However, fibrous xylem vessels have been observed in roots of ‘Rangpur’ lime plants (Citrus limonia L.) when exposed to Al, which could affect the functioning of aquaporins, ultimately reducing their expression. We confirmed a decrease of CO2 assimilation (A), stomatal conductance (gs), transpiration (E) and relative leaf water content (RWC) in 3-month-old C. limonia plants exposed to 1480 μM Al in nutrient solution for 90 days. The estimated hydraulic conductivity from soil to the leaf (KL) and leaf water potential (Ψw) also showed low values, although not consistently reduced over time of Al exposure. The relative expression of aquaporin genes belonging to PIP family (PIP1-1, PIP1-2 and PIP2) showed downregulation for ClPIP1-1 and ClPIP2 and upregulation for ClPIP1-2 in plants exposed to Al. Furthermore, ClPIP1-1 was positively correlated with A and gs in plants exposed to Al. Therefore, downregulation of ClPIP1–1 and ClPIP2 in roots of ‘Rangpur’ lime plants could be associated with the low leaf hydration of this species when exposed to Al.
Variations in soil fungal communities after continuous fertiliser treatment under the ridge and furrow rainfall harvesting system in a semiarid region of China
Authors: Zhang Yan , Ma Qian , Wang Yingxin , Hu Zhilin , Liu Donghua , Ning Yanshan , Jia Zhikuan , Zhang Peng
Published: December 2019

The ridge and furrow rainfall harvesting (RFRH) system enhances the rainfall use efficiency and crop yield in rain-fed areas of north-western China. In this study, we determined the effects of RFRH on the soil fungal community composition and diversity in a 5-year fertilisation experiment (N:P fertiliser rates of 0:0, 150:75, 300:150, and 450:225 kg ha–1 year–1) in the dryland farming area of the Loess Plateau. Excessive fertiliser application reduced the crop productivity and a moderate rate of 300:150 kg ha–1 year–1) produced the highest maize yield. The available phosphorus (AP), organic carbon, nitrate-nitrogen (NO3-N) and total nitrogen contents increased with the fertiliser rate, whereas soil water content decreased. The relative abundances of Ascomycota, Fusarium and Zygomycota increased (P < 0.05) with the fertiliser application rate, whereas those of Basidiomycota and Glomeromycota decreased (P < 0.05). The fungal diversity (Shannon–Wiener index: P = 0.016) and composition (unweighted UniFrac: P = 0.024) were significantly affected by fertilisation. The NO3-N and AP were the main factors that affected fungal composition and diversity. Thus, fertilisation changed the fungal community composition and diversity, and a higher fertiliser rate negatively affected nutrient cycling and the stability of the soil ecosystem under RFRH.