bluuebunny/crossref_metadata_2025 huggingface dataset:
Preliminary Novel Analysis on Antimicrobial Properties of Concentrated Growth Factor against Bacteria-Induced Oral Diseases
Authors: Alauddin Muhammad Syafiq , Yusof Nabilah Mohd , Adnan Aini Sufinah , Said Zulfahmi
Published: February 2022

Objective Concentrated growth factor (CGF) is particularly gaining acceptance and popularity in regenerative dentistry. Nonetheless, there are no available studies showing its effect against microorganisms of oral cavity particularly in chronic oral disease-induced biofilms. This in vitro research was conducted to determine the antimicrobial effects of CGF against Staphylococcus aureus sp. (S. aureus) and Streptococcus mutans sp. (S. mutans).

Materials and Methods Blood samples were obtained from a healthy volunteer. CGF was then prepared using specialized centrifugation equipment (Medifuge, Silfradent, Santa Sofia FC, Italy) and protocol. Antimicrobial activity of the CGF was observed and recorded on standard strains of S. aureus and S. mutans using a well diffusion method to determine the inhibition zone, broth microdilution to determine minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), and crystal violet assay for biofilm assessment, with chlorhexidine (CHX) 0.12% used as a positive control. Statistical analysis was then performed using one-way analysis of variance followed by Tukey Test post hoc analysis.

Results It was observed that there was a presence of clear zones of inhibition around the CGF after 24 hours of incubation. The mean diameter of the inhibition zone was 1.26 ± 0.12 nm and 1.20 ± 0.06 nm for S. aureus and S. mutans, respectively, with significance difference (p < 0.05) against the control group CHX 0.12%. The MIC values of the CGF against S. aureus and S. mutans were 47.9% and 34.17%, respectively, and the MBC values of the CGF against S. aureus and S. mutans were 100%. The viability and the ability in inhibiting the biofilm formation of S. mutans and S. aureus following treatment with CGF showed a reduction in the concentration-dependent manner as compared with the control group.

Conclusion CGF possesses antimicrobial and antibiofilm activity against S. aureus and S. mutans.
Efficacy and Safety of SGLT2 Inhibitors as Adjunctive Treatment in Type 1 Diabetes in a Tertiary Care Center in Saudi Arabia
Authors: Fallatah Walla , Brema Imad , Alobedallah Ahmed , Alkhathami Reem , Zaheer Shawana , AlMalki Eyad , Almehthel Mohammed , Alzahrani Saad , AlMalki Mussa H.
Published: February 2022

Background Adjunctive treatment with sodium-glucose co-transporters 2 inhibitors (SGLT2- I) has been successfully used in patients with type 1 diabetes mellitus (T1DM) in recent years to improve glycemic control and reduce body weight without increasing the risk of hypoglycemia; however, there is a scarcity of evidence for real-world experience in their use in T1DM Saudi patients. The purpose of this study was to evaluate the efficacy and safety of empagliflozin as off-label adjunctive therapy in Saudi patients with T1DM.

Methods This study was a retrospective study for T1DM patients, who were prescribed empagliflozin as an adjunctive therapy. Baseline characteristics including age, changes in HbA1c, body weight, total daily insulin dose, lipid profile, and well as side effects such as urinary tract infections (UTIs) and diabetes ketoacidosis (DKA) were evaluated before and after initiation empagliflozin in 37 T1DM patients.

Results The mean age was 25.8 ± 8.0 years, mean weight was 75.3 ± 14.8 kg, mean body mass index (BMI) was 28.1 ± 6.7 kg/m2, mean duration of diabetes was 10.1 ± 6.5 years, and mean HbA1c was 9.4 ± 1.4%. After a mean follow-up duration of 15.8 ± 6.0 months, the mean reduction in the HbA1c% from baseline was 0.82% (p = 0.001) and mean weight reduction from baseline was 1.7 kg (p = 0.097). The total daily insulin dose was decreased by 2.9 units. UTIs and DKA episodes were reported among 2.7% and 10.8% of the participants, respectively.

Conclusion Empagliflozin in combination with insulin in overweight Saudi T1DM subjects resulted in a significant improvement in glycemic control, mild non-significant reduction in body weight, and a small but statistically significant reduction in the total daily insulin dose with a slight increase in the risk of DKA and UTIs. Further larger prospective studies are needed for better evaluation of the efficacy and safety of these agents in Saudi T1DM patients.
Early Extubation in Children after Cardiac Surgery. Initial Experience from a Tertiary Care Hospital in Mexico City
Authors: Figueroa-Solano Javier , Infante-Sánchez Karen , Espinosa-Guerra Kenia , Astudillo-De Haro Esteban David , Martínez-Albarenga Paola María , Lesprón-Robles Ma del Carmen , Molina-Méndez Francisco Javier , Miranda-Chávez Irma Ofelia
Published: February 2022

Early extubation (EE) in pediatric cardiac surgery has demonstrated important benefits. However, ventilating them for 24 hours or more (delayed decannulation, DD) is an enduring practice. The objectives of this study were to describe the clinical profiles of EE in our setting and analyze its impact and the factors that prolong mechanical ventilation. Children operated on for cardiac surgery from 2016 to 2017 were included. Data were obtained from an electronic database. Comparisons were performed with Pearson's chi-square test, Student's t-test, or Mann–Whitney U test. Multivariate logistic regression was used to evaluate factors associated with DD. Of 649 cases, 530 were extubated on one occasion. EE was performed in 305 children (57.5%): 97 (31.8%) in the operating room and 208 (68.2%) in the intensive care unit (ICU). Reintubation (RI) occurred in 7.5% with EE and 16.9% with DD (p = 0.001). Fewer complications and ventilation time and decreased ICU and hospital length of stay resulted with EE. Age, presurgical ventilation, emergency surgery, pump time, attempts to weaning from cardiopulmonary bypass, bleeding greater than usual, and CPR in surgery were associated with DD. EE in the National Institute of Cardiology (INC; Spanish acronym) is in the middle category and has shown benefits without compromising the patient; the fear of further complications, RI, or death is unfounded. Although not all children at the INC can be decannulated early, if there are no or minimal risk factors, it should be a priority.
Nasal Septal Perforation Reconstruction with Polydioxanone Plate: A Systematic Review
Authors: Levin Marc , Ziai Hedyeh , Shapiro Justin , Roskies Michael G.
Published: February 2022

Nasal septal perforation is an uncommon pathology that is difficult to surgically repair and may significantly impact patients' quality of life. Existing treatments have high complication and failure rates. The use of polydioxanone (PDS) plates to repair septal perforations is an innovative approach that has demonstrated superior outcomes to the conventional techniques. This study aimed to review the literature on PDS plates for nasal septal perforation reconstruction. PubMed, OVID Medline, and OVID Embase databases were searched for relevant articles in June 2021. Search terms included nasal septal perforation, polydioxanone, septal perforation, septal repair, nasal septum, and PDS plate. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines were adhered to for this systematic review. Database searches yielded 80 articles. Seven articles were included representing 74 patients. All studies reported the use of PDS plates in addition to other materials. They all reported closure rates of at least 80%. The majority of studies reported no postoperative complications. Nasal septal perforation reconstruction with PDS plates is a promising approach that has demonstrated positive outcomes. Further larger studies are required to evaluate the long-term efficacy of using PDS plates on patients with septal perforations.
Biaxial paramagnet: Manifestation of the electro-magneto-elastic coupling
Authors: Zvyagin A. A. , Zvyagina G. A.
Published: February 2022

The effect of the coupling between the spin (magnetic), electric, and elastic subsystems of the biaxial paramagnetic crystal has been studied. Relative changes of the electric permittivity, piezoelectric modules, elastic modules, and the magnetic susceptibility of such a system have been calculated. It has been shown that the external electric field, polarized in the plane, perpendicular to the external magnetic field, depending on its polarization, can change the effective symmetry of the crystal, reducing it to the monoclinic symmetry, or enlarging it to the tetragonal (with one distinguished axis) one. Those changes of the symmetry manifest themselves in the special features in the behavior of various calculated characteristics of the paramagnetic crystal with coupled magnetic, electric, and elastic subsystems.
Developments in cryodeformation: Upsetting under all-round compression
Authors: Tikhonovsky M. A. , Khaimovich P. A. , Kolenov I. V. , Shul’gin N. A. , Okovit V. S.
Published: February 2022

The new method of cryodeformation under all-around compression conditions is described. The impossibility of existing technologies to increase the efficiency of combined treatment of low-plasticity materials (in particular, the “upsetting-extrusion” method) by temperature treatment decreasing to the cryogenic region are considered. The technical possibility of such cryodeformation is discussed. The construction and operation principle of the developed device is described. The treatment efficiency of low-plasticity materials by this device on the example of technical magnesium and titanium nickelide alloy is shown. The need to clarify the formulations used to designate the methods of metals cryodeformation under conditions of all-round compression is discussed.
3D printing linear accelerators reduces cost and complexity
Authors: Piccone Ashley
Published: February 2022

3D printing by selective laser melting and changes to cavity geometry aim to optimize the centerpiece of accelerator facilities
Using green fluorescent proteins to detect protein aggregation in live cells
Authors: McConnon Aili
Published: February 2022

Fluorophores can turn on fluorescence when protein misfolds for biological imaging
Tunnel magnetodielectric effect: Theory and experiment
Authors: Cao Yang , Kobayashi Nobukiyo , Masumoto Hiroshi
Published: February 2022

The recently discovered tunnel magnetodielectric (TMD) effect—the magnetic field-induced increase in the dielectric permittivity (ε′) of nanogranular composites caused by the spin-dependent quantum mechanical charge tunneling—is of interest for both the scientific value that combines the fields of magnetoelectric and spintronics and multifunctional device applications. However, little is known about how large the maximum dielectric change Δε′/ε′ can achieve and why the Δε′/ε′ variations obey the dependence of square of normalized magnetization (m2), which are critically important for searching and designing materials with higher Δε′/ε′. Here, we perform approximate theoretical derivation and reveal that the maximum Δε′/ε′ can be estimated using intrinsic tunneling spin polarization (PT) and extrinsic normalized magnetization (m), that is, Δε′/ε′ = 2PT2m2. This formulation allows predicting over 200% of theoretical limit for m = 1 and accounts for the observed m2 dependence of Δε′/ε′ for a given PT. We experimentally demonstrate that x-dependence of Δε′/ε′ in (CoxFe100−x)–MgF2 films is phenomenologically consistent with this formulation. This work is pivotal to the design of ultra-highly tunable magnetoelectric applications of the TMD effect at room temperature.
A perspective on optimizing photoelectric conversion process in 2D transition-metal dichalcogenides and related heterostructures
Authors: Dong Jiansheng , Zhao Yipeng , Ouyang Gang , Yang Guowei
Published: February 2022

As a type of layered two-dimensional (2D) structure, transition-metal dichalcogenides (TMDs) and related heterostructures have recently received much attention in applications such as electronics, optoelectronics, and energy conversion/storage. The changes in the atomic bond nature in 2D TMDs, including bond length, bond angle, and bond energy, are the key factors affecting the performance of these systems. Some modulations, such as strain engineering and geometry effect, provide effective methods to enhance the related performance of devices constructed by 2D TMDs by a change in the bond nature. In this Perspective, we review our recent works done on photoelectric conversion properties of 2D TMDs and related heterostructures under various conditions, analyze the underlying mechanism of different modulation modes, and then identify the key factors determining optimal optoelectronic properties at the atomic level.
Simulation of targeted magnetic drug delivery: Two-way coupled biomagnetic fluid dynamics approach
Authors: Gul Aaiza , Tzirtzilakis Efstratios E. , Makhanov Stanislav S.
Published: February 2022

Due to significant advances in nanomedicine, magnetic nanoparticles (MNs) have emerged as a promising carrier in targeted magnetic drug delivery (TMDD) systems. Therefore, this paper presents a computational model for optimized magnetic navigation of MNs coated with the anticancer drugs inside the blood vessels. A mixture of blood and MNs is represented as a one-phase solution in the majority of TMDD models. The preceding two-phase models are usually one-way coupled, i.e., the blood flow has a significant influence on the MNs flow. However, the inverse effect of the MNs on the blood flow is not taken into account. To overcome these limitations, the MNs in a blood vessel are simulated by a two-phase (solid–liquid) flow governed by two-way coupled momentum and temperature equations for the blood flow and the MNs. The numerical procedure invokes the stream function–vorticity formulation and an efficient numerical method on a finite-difference grid. The model, validated by the experimental results, has been applied to analyze the formation of vortices relative to the magnetic force and the drag force and the zones of TMDD, where the velocity of the blood flow is low and the velocity of the MNs is high toward the magnet. The model has been verified against the existing models and the experimental data. The numerical results show that the magnetohydrodynamics slows down the blood flow and smooths vortices created by Ferrohydrodynamics. The size of the drug-loaded MNs on the velocity and the temperature of the blood has been evaluated.
Spin-voltage-driven efficient terahertz spin currents from the magnetic Weyl semimetals Co2MnGa and Co2MnAl
Authors: Bierhance Genaro , Markou Anastasios , Gueckstock Oliver , Rouzegar Reza , Behovits Yannic , Chekhov Alexander L. , Wolf Martin , Seifert Tom S. , Felser Claudia , Kampfrath Tobias
Published: February 2022

Magnetic Weyl semimetals are an emerging material class that combines magnetic order and a topologically non-trivial band structure. Here, we study ultrafast optically driven spin injection from thin films of the magnetic Weyl semimetals Co2MnGa and Co2MnAl into an adjacent Pt layer by means of terahertz emission spectroscopy. We find that (i) Co2MnGa and Co2MnAl are efficient terahertz spin-current generators reaching efficiencies of typical 3d-transition-metal ferromagnets such as Fe. (ii) The relaxation of the spin current provides an estimate of the electron-spin relaxation time of Co2MnGa (170 fs) and Co2MnAl (100 fs), which is comparable to Fe (90 fs). Both observations are consistent with a simple analytical model and highlight the large potential of magnetic Weyl semimetals as spin-current sources in terahertz spintronic devices. Finally, our results provide a strategy to identify magnetic materials that offer maximum spin-current amplitudes for a given deposited optical energy density.
Principles, modulation, and applications of fluorescent protein chromophores
Authors: Ye Songtao , Tang Yuqi , Zhang Xin
Published: February 2022

Fluorescent proteins (FPs) have gained much attention over the last few decades as powerful tools in bioimaging since the discovery of green fluorescent protein (GFP) in the 1960s. The mechanism of FP bioluminenscence has been well-studied, and new variants with improved photophysical properties are being constantly generated. In this review, a brief history of GFP along with its biogenesis is first provided. Next, the fluorescent and quenching mechanism governing the photophysical property of GFP is elaborated. Most importantly, we seek to introduce the expanding family of FP derivatives that mimics the chromophore core structure of FPs. Multiple physical and chemical strategies have been discussed to minimize the inherent fluorescence quenching effect of FP derivatives. Finally, we briefly overview the biological application of FP derivatives, with a focus on fluorescent RNA aptamer and recently reported protein aggregation detection probes. Through citing and discussing the most important works in this field, this review aims to provide a general photophysical understanding regarding the luminescence phenomenon of GFP and its derivatives, as well as chemical strategies to design functional FP derivatives.
Rotation induced symmetry change of friction coefficient of water on graphene/h-BN heterostructures
Authors: Zhu Huimin , Zhang Wei , Ye Chao , Shi Jiaqi , Lu Wenxi
Published: February 2022

The graphene/h-BN heterostructure provides a promising device for biomedical applications and biosensor. However, the friction characteristics of water on graphene/h-BN are still elusive. By means of molecular dynamics simulations, we investigated the friction coefficient of water on both sides of graphene/h-BN heterostructures under various rotation angle, which shows a non-monotonic but symmetrical variation with relative interlayer angle. Despite that friction coefficient of h-BN surface is larger than that of graphene, as the rotation angle increases, the friction coefficient of water on both sides of the graphene/h-BN heterostructure exhibits the same “M”-shaped curve. The center of symmetry of the curve is at the rotation angle of 30°; the friction coefficient is the largest when the rotation angle is 10° and 50°. It was found that graphene/h-BN heterostructure is a device whose friction coefficient is different on both sides and can be adjusted by twisting the relative interlayer angle. These results could be demonstrated by the van der Waals interaction and different pattern of free energy landscape. These findings provide detailed insights into the mechanism of the friction property of water at nanoscale, which would facilitate feasible applications of graphene/h-BN heterostructure in biosensor and biomedicine.
Tunneling characteristics of weakly coupled Majorana wire arrays
Authors: Rana Deepti , Sheet Goutam
Published: February 2022

The Majorana modes in solid-state systems have the potential to be applied in fault tolerant quantum computing. It is well known that a semiconducting nanowire with strong Rashba coupling and in the proximity of a superconductor hosts Majorana edge modes. An array of such nanowires with inter-wire coupling gives an approximate description of a two-dimensional topological superconductor, where depending on the strength of the magnetic field and the chemical potential, a rich phase diagram hosting trivial and different types of non-trivial phases can be achieved. In this work, we theoretically consider such a two-dimensional assembly of spin–orbit coupled superconducting nanowires and calculate the collective tunneling conductance between normal electrodes and the wires in the topological regime. When the number of wires in the assembly is N, as a consequence of the way the Majorana bonding and anti-bonding states form, we find that N conductance peaks symmetric about the bias V=0 appear for even N. When N is odd, a zero-bias conductance peak (ZBCP) also appears. We have identified the region in the parameter space where this odd–even rule applies. The effects of finite temperature, finite dissipation, and the barrier potential on the conductance profiles have also been discussed in detail. A device comprising of an array of weakly coupled Majorana wires can be realized by standard nano-fabrication techniques where individual nanowires can be turned ON or OFF by using a mechanical switch (or local top gating) to make N either even or odd—thereby switching the ZBCP OFF or ON, respectively, modulo the control parameter being in the desired range. Hence, in principle, our results can be used to realize and detect topological superconductivity efficiently and in a controlled manner.
Numerical investigation on the recovery process of the flow field in a rotating duct
Authors: Wu Qi , Jin Hanhui , Wang Canxing , Fan Jianren
Published: February 2022

Turbulent flow inside a rotating duct widely exists in revolving hydromachines. The Coriolis force and the centrifugal force generated in the rotation greatly modify the development of the flow field and consequently affect the efficiency of these hydromachines. A deviation of the mainstream to the pressure sidewall of the duct, which occurs as soon as the fluid flows to the rotating duct, is commonly observed and previously thought to remain throughout the flow field. However, this study discovers a recovery process of the modified flow field and numerically investigates that process for the first time. The recovery process begins very close to the entrance of the duct and ends when the same fully developed flow field as that without rotation is obtained. The results indicate that the recovery process can be divided into four phases: the linear recovery phase, stationary mixing phase, nonlinear recovery phase, and finish of the recovery process. The characteristic details of the four phases and the evolving mechanisms of the recovery process are discussed. The algebraic relationships between the characteristic parameters of the recovery process and the inflow conditions (the rotation velocity, rotation numbers, mean inflow velocity, and height of the duct) are obtained. It is found that the characteristic deviation distance of the velocity peak in the linear recovery phase linearly moves toward the centerline of the duct with a slope of k=−0.0023ω+0.0748. The recovery distance linearly increases with the product of the mean streamwise velocity U and the rotation velocity ω as follows: (XsH)0.2=0.025U·ω+b. It also denotes that the recovery process can be accelerated by reducing the height H of the duct. Accelerating the recovery process and reaching the ideal optimal velocity distribution as soon as possible can effectively improve the efficiency of the flow field.
Thermally driven magnon valve with perpendicular magnetic anisotropy
Authors: Vilela G. L. S. , Santos E. , Abrao J. E. , Rodrigues A. R. , Rezende S. M. , Azevedo A. , Moodera J. S.
Published: February 2022

The active manipulation of quasiparticles, other than electrons, is a feasible alternative for developing the next generation of devices for information processing. Exploring magnons is advantageous as they can travel far and fast due to their low dissipation and high group velocity, transferring spin without charge transport, thus reducing the Joule heating. Moreover, magnon currents can switch a film's magnetization via a magnon torque facilitated by a perpendicular magnetic anisotropy (PMA). We demonstrate the proof of principle for three states' memories via transport studies of thermally excited magnon currents at room temperature in ferrimagnetic insulating magnon valves TmIG/Au/TmIG with PMA. While varying the relative TmIG magnetizations orientation, magnon currents excited in TmIG films are detected as a voltage in a top platinum electrode film due to the inverse spin Hall effect. The magnon transmission is maximum in the parallel state where the two signals sum up. Possibilities are seen for wave-based nonvolatile magneto-resistive random-access memory, sensing, and logic devices.
Increasing the proportion of Leucaena leucocephala in hay-fed beef steers reduces methane yield
Authors: Stifkens A. , Matthews E. M. , McSweeney C. S. , Charmley E.
Published: February 2022

Context Leucaena leucocephala (leucaena) is a leguminous shrub adapted to higher rainfall (>600 mm) in frost-free areas of Australia. It can be a source of high-quality forage for cattle grazing tropical grass-based pastures that are seasonally deficient in the nitrogen content required for adequate levels of performance. Leucaena contains bioactive compounds that may reduce methanogenesis in the rumen, helping to achieve Australia's goal to make red meat production carbon neutral by 2030. Aim A study was undertaken to evaluate the response in animal performance and methane production to increasing percentages of leucaena in a hay-based diet. Methods Growing steers were fed diets containing 0%, 18%, 36% and 48% leucaena. Intake, liveweight gain, methane production and yield were measured in a cross-over trial with two modern cultivars of leucaena (Redlands and Wondergraze). Methane was measured in open-circuit respiration chambers. Key results There were no effects of cultivar on most parameters. Increasing leucaena percentage in the diet increased dry matter intake, animal performance and methane production (g/day) but reduced methane yield (g/kg dry matter intake) according to the equation: methane yield = 19.8 − 0.09 × leucaena percentage in the diet. The inclusion of polyethylene glycol to nullify potential antimethanogenic activity of tannins restored methane yield by 67%, indicating that tannins were responsible for most of the observed reduction in methane yield. Conclusion The results demonstrate that leucaena can improve animal performance and reduce methane yield in steers fed low-quality grasses. Implications Leucaena can be included in diets of grazing cattle in areas agronomically suited to its production, as a means to reduce enteric methane emissions.
Root/shoot responses to drought and flooding of bahiagrass at reproductive stage depends on genotype ploidy
Authors: Bortolin Gabriel S. , Galviz Yutcelia C. , Pedroso Carlos E. S. , Souza Gustavo M.
Published: February 2022

Severe water stress is responsible for reducing plant growth and reproduction. This study aimed to evaluate the physiological and biochemical mechanisms associated with the tolerance of two genotipes of bahiagrass (Paspalum notatum Flügge) with different ploidy level to water deficit and flooding at the reproductive stage. Photosynthetic performance of diploid and tetraploid plants was not affected by flooding. In contrast, the water deficit decreased stomatal conductance, increased leaf temperature, and resulted in a decrease in the assimilation rate of the two genotypes. Despite the greater activities of antioxidant enzymes, flooded roots accumulated hydrogen peroxide and malondialdehyde. Roots of plants exposed to water deficit maintained an accumulation of biomass similar to that of control plants; however, with higher levels of total phenol content, total soluble sugars and proline. Diploid plants subjected to flooding had more inflorescences, however, the drought reduced the total number of filled florets per plant. Less starch degradation allows the maintenance and recovery of biomass in the tetraploid genotype, which allows it to maintain its reproductive performance even under drought conditions. Overall, the synthesis of osmoprotectants and activation of antioxidant machinery are important strategies in the tolerance of bahiagrass to water stress at the reproductive stage.
Systematic modeling-driven experiments identify distinct molecular clockworks underlying hierarchically organized pacemaker neurons
Authors: Jeong Eui Min , Kwon Miri , Cho Eunjoo , Lee Sang Hyuk , Kim Hyun , Kim Eun Young , Kim Jae Kyoung
Published: February 2022

Significance

The hierarchically organized master and slave clock neurons are widely believed to generate circadian rhythms via an identical molecular clockwork. However, their different roles in regulating those rhythms raise the question of whether their molecular clockworks differ. Here, leveraging systematic model-driven in vivo experiments for an unbiased search for their heterogeneity, we found that the master clock neurons have higher synthesis and turnover rates of repressor and lower activator levels than the slave clock neurons. Further in silico analysis revealed that this distinguished molecular clockwork of the master clock neurons allows them to generate strong rhythms but also to flexibly adjust rhythms upon environmental perturbation. This explains how the circadian clock can have two contradictory properties, robustness and flexibility.
Rapid basal melting of the Greenland Ice Sheet from surface meltwater drainage
Authors: Young Tun Jan , Christoffersen Poul , Bougamont Marion , Tulaczyk Slawek M. , Hubbard Bryn , Mankoff Kenneth D. , Nicholls Keith W. , Stewart Craig L.
Published: February 2022

Significance

Subglacial drainage systems control ice sheet flow and the quantity of ice discharged into the ocean. However, these systems are currently poorly characterized, from a lack of direct observations. This shortcoming is problematic, as changes in drainage systems can result in a markedly differently ice sheet response. Here, we present a radar-derived record of basal melt rates with colocated borehole observations, showing unexpectedly warm subglacial conditions beneath a large outlet glacier in West Greenland. The record is unprecedented because the observed basal melt rates are several orders of magnitude higher than predictions and previous estimates. Our observations show that the effect of viscous dissipation from surface meltwater input is by far the largest heat source beneath the Greenland Ice Sheet.
Background-suppressed tumor-targeted photoacoustic imaging using bacterial carriers
Authors: Gao Rongkang , Liu Feng , Liu Wenfeng , Zeng Silue , Chen Jingqin , Gao Ruru , Wang Liang , Fang Chihua , Song Liang , Sedgwick Adam C. , Sessler Jonathan L. , Chu Jun , Yan Fei , Liu Chengbo
Published: February 2022

Significance

Photoacoustic (PA) imaging can provide information about deep-seated biological tissues. Unfortunately, signal intensity and resolution can be limited by background signals arising from endogenous chromophores. Photochromism, the use of agents that go from colorless to colored, has been suggested to be a promising avenue to overcome this limitation. However, a viable method that allows practical applications of this so-called background-suppressed PA imaging is still lacking. Here, we report the engineering of a phytochrome-based reporter protein (mDrBphP-PCMm/F469W) that displays high photoswitching contrast. Its expression inEscherichia colienables point-specific imaging within the tumor region over several days and permits PA monitoring of deep-seated tumor tissues via reduction of background signals.
A back-up source of microtubules for the midbody during cytokinesis
Authors: Hickson Gilles R.X.
Published: February 2022

During cytokinesis, microtubules become compacted into a dense midbody prior to abscission. Using genetic perturbations and imaging of C. elegans zygotes, Hirsch et al. (2022. J. Cell Biol.https://doi.org/10.1083/jcb.202011085) uncover an unexpected source of microtubules that can populate the midbody when central spindle microtubules are missing.
Point charge representations of multipoles
Authors: Majic Matt
Published: February 2022

We generalize the notion of a dipole made of two point charges placed infinitesimally close together to multipoles of all degrees. The charge distributions are derived first by differentiating the delta function for the monopole in the same way that differentiating the potential 1/r generates the spherical multipoles

r

−
ℓ
−
1

P

ℓ

m

(

cos

θ

)

e

i
m
ϕ

. This method surprisingly generates messy distributions for spherical multipoles with m ⩾ 3. So instead we use a ‘bracelet’ of 2m charges for the planar spherical multipoles of order m = ℓ, and stack these to construct multipoles for all m, ℓ. We show that the spherical multipoles of degree ℓ can be made of ℓ + 1 charges for m = 0 and 2m(ℓ − m + 1) charges for 1 ⩽ m ⩽ ℓ. A similar construction is found for the Cartesian multipoles.
Seeing better in nature: contrast enhancement by near infrared imaging
Authors: Vollmer Michael , Shaw Joseph A
Published: February 2022

The present paper deals with the question: why is long-distance contrast improved when imaging in the near infrared? This is intimately related to the even broader question, why do we see what we see? The latter is a fundamental general question of optics, connecting the fields of imaging with human and/or camera vision. We first describe the concepts of perception and contrast in general and then discuss the physics background by comparing visible and near infrared images of various natural scenes. Our focus is on the often utilized contrast enhancement in the near infrared range, i.e. on the question of how much clearer we might be able to see if we could see in the near infrared.
Comparative analysis and tests for an improved frequency tuning area-varying electrode considering the influence of fringe capacitance
Authors: Wang Xuetong , Zheng Xudong , Wu Haibin , Shen Yaojie , Liu Guowen , Jin Zhonghe , Ma Zhipeng
Published: February 2022

In this paper, an improved area-varying tuning electrode with better immunility to fringe capactor is proposed, analyzed and tested, which is mainly used for frequency tuning of micromechanical gyroscopes. Based on the existing area-varying tuning electrode Hu et al (2013 J. Microelectromech. Syst.
22 909–18), this paper firstly analyzes the capacitance of the tuning electrode, and obtains the relationship between the capacitance and the displacement using both the analytic formula and finite element analysis, verifying that the fringe capacitance in area-varying tuning electrode decreases the tuning ability of both up-tuning electrode and down-tuning electrode. Then, parametric scanning method is used to optimize the geometry parameter of the tuning electrode, which reduces the influence of fringe capacitance and increases the tuning ability of the tuning electrode. Contrast experiments and tests are carried with gyroscope samples with tuning electrodes before and after optimizing. The tested mean value of tuning ability of the improved tuning electrode is improved by 95.7% after opimization.
Theoretical study of high-order harmonic generation in solutions
Authors: Xia Chang-Long , Liu Jia-Qi , Lü Ling-Jie , Zeng Ai-Wu , Li Zheng-Liang , Bian Xue-Bin
Published: February 2022

High-order harmonic generation (HHG) in disordered systems is investigated by numerically solving the time-dependent Schrödinger equation. We reveal the vital role of Anderson localization in this situation. It allows us to develop a new and efficient sampling method for the large disordered system, which could significantly reduce the computation cost. It can be applied to both pure liquids and solutions. The structures and cutoffs of the harmonic spectrum are simulated with different field strengths and statistical parameters in the solution. Compared with HHG in pure liquids, the harmonic signal changes little in dilute solutions. HHG from different solutes and concentrations is simulated to confirm this point. This should be the first theoretical study on HHG in solutions. Our results shed light on the way to investigate the ultrafast processes in the solution.
Methane detection to 1 ppm using machine learning analysis of atmospheric pressure plasma optical emission spectra
Authors: Shah Mansouri Tahereh , Wang Hui , Mariotti Davide , Maguire Paul
Published: February 2022

Optical emission spectroscopy from a small-volume, 5 μl, atmospheric pressure RF-driven helium plasma was used in conjunction with partial least squares-discriminant analysis for the detection of trace concentrations of methane gas. A limit of detection of 1 ppm was obtained and sample concentrations up to 100 ppm CH4 were classified using a nine-category model. A range of algorithm enhancements were investigated including regularization, simple data segmentation and subset selection, feature selection via Variable Importance in Projection and wavelength variable compression in order to address the high dimensionality and collinearity of spectral emission data. These approaches showed the potential for significant reduction in the number of wavelength variables and the spectral resolution/bandwidth. Wavelength variable compression exhibited reliable predictive performance, with accuracy values >97%, under more challenging multi-session train—test scenarios. Simple modelling of plasma electron energy distribution functions highlights the complex cross-sensitivities between the target methane, its dissociation products and atmospheric impurities and their impact on excitation and emission.
Giant magnetoresistance in spin valves realized by substituting Y-site atoms in Heusler lattice
Authors: Zhang Lei , Zhang Binyuan , Jiang Liwei , Zheng Yisong
Published: February 2022

‘All-Heusler’ spin-valve constructed by two half-metallic Heusler electrodes and a non-magnetic Heusler spacer contains two interfaces that have a crucial influence on the magnetoresistance. In order to reduce the disorder at the interface and protect the half metallicity of the electrode at the same region, we propose a scheme to construct a spin valve by replacing the Y-site atoms in the half-metallic Heusler electrode to obtain the corresponding non-magnetic spacer based on the Slater–Pauling rule. In this way, the lattice and band match of the two materials can be ensured naturally. By using Co2FeAl as electrode and Co2ScAl as the spacer materials, we construct the Co2FeAl/Co2ScAl/Co2FeAl(001)-spin valve. Based on the first-principles calculation, the most stable FeAl/CoCo-interface is determined both from the phonon spectra and the formation energy when the spacer Co2ScAl grows on the FeAl-terminated (001) surface of electrode material Co2FeAl. By comparing the projected density of states of the interfacial atoms with the corresponding density of states of the bulk electrode material, only the value of spin-up state of Al changes from 0.17 states/atom/eV to 0.06 states/atom/eV before and after substitution, the half metallicity at the interface is maintained. As a result, the spin-dependent transport properties show significant theoretical magnetoresistance MRop which can reach up to 1010% and much larger than 106% reported before.
Monomeric-to-pentameric aggregation of molecular Cs4PbBr6 halide perovskite: a first-principles investigation
Authors: Zhang Lei , Hu Wenguang
Published: February 2022

The zero-dimensional halide perovskite, including the molecular state of the halide perovskite represented by A4BX6, has received much attention for their optoelectronic applications. In this manuscript, we employ first-principles calculations to systematically investigate the aggregation of the molecular Cs4PbBr6 halide perovskite. The monomeric, dimeric, trimeric, tetrameric and pentameric forms of Cs4PbBr6 are constructed. The structures of the aggregates are stabilized via the halogen bonds and the sharing of the A-site cations, and the charge transfer features from the halogen to the cesium species are observed upon the light excitation. Monotonic electronic band gap reductions and systematic red-shifts in the UV–vis absorption spectra are observed as the aggregation shifts to the higher degree. The detailed structural and electronic properties of the aggregates are further examined via the calculation of the Fukui function, electrostatic potential and frontier orbital energy levels. The present study facilitates the fundamental understanding of the higher-degree aggregates of the molecular halide perovskites and their structure-properties relationships for the optoelectronic applications such as the solar cells and photodetectors where the band gaps and the light-absorbing properties are essential.
Development of 2NN MEAM potential for Fe–Al and atomistic investigation of surface and interface properties of the inhibition layer in galvanized Fe
Authors: Chen Kefan , Mun Sungkwang , Baskes Michael , Horstemeyer Mark , Li Bin
Published: February 2022

Hot-dip Zn coating or galvanizing is an important process for high strength steels that are extensively used in automotive industries. During galvanizing, Fe in the steel substrate quickly reacts with Al that is dissolved in the Zn bath and an inhibition layer is formed. To better understand the formation of the inhibition layer that occurs on a small scale (typically ∼100 nm), it is necessary to understand the physical properties of the interfacial phases on the atomic scale. In the present work, we develop a second nearest neighbor Fe–Al modified embedded atom method (MEAM) potential to calculate the surface and interface properties of the inhibition layer. The as-developed potential is able to well describe the complex crystal structure of the inhibition layer. Also, this potential satisfies three criteria for the experimentally observed phases: phase stability, convex hull, and elastic stability. The calculation results show a negative interfacial energy between Fe and the inhibition layer, a manifestation of the high affinity between Fe and Al. The formation of the inhibition layer on the Fe surface lowers the interfacial energy. Our results also show that the crystal orientation of Fe strongly affects the interfacial energy, and the (110) plane gives the lowest interfacial energy. The work of adhesion is also calculated with the developed MEAM potential, and the results agree well with the results obtained by other methods.
Glutathione-sensitive IPI-549 nanoparticles synergized with photodynamic Chlorin e6 for the treatment of breast cancer
Authors: Yang Mengjia , Lv Xiaojun , Zhan Siwen , Lu Mengli , Zhang Xueqiong , Qiu Tong
Published: February 2022

We combined phosphoinositol-3-kinin inhibitor IPI-549 and photodynamic Chlorin e6 (Ce6) on carboxymethyl chitosan to develop a novel drug delivery nanoparticle (NP) system (Ce6/CMCS-DSP-IPI549) and evaluate its glutathione (GSH) sensitivity and targeting ability for breast cancer treatment. The NPs were spherical with a uniform size of 218.8 nm, a stable structure over 7 days. The maximum encapsulation efficiency was 64.42%, and NPs drug loading was 8.05%. The NPs released drugs within tumor cells due to their high GSH concentration, while they maintained structural integrity in normal cells, which have low GSH concentration. The cumulative release rates of IPI-549 and Ce6 at 108 h were 70.67% and 40.35% (at GSH 10 mM) and 8.11% and 2.71% (at GSH 2 μM), respectively. The NPs showed a strong inhibitory effect on 4T1 cells yet did not affect human umbilical vein endothelial cells (HUVECs). After irradiation by a 660 nm infrared laser for 72 h, the survival rate of 4T1 cells was 15.51%. Cellular uptake studies indicated that the NPs could accurately release drugs into tumor cells. In addition, the NPs had a good photodynamic effect and promoted the release of reactive oxygen species to damage tumor cells. Overall, the combination therapy of IPI-549 and Ce6 is safe and effective, and may provide a new avenue for the treatment of breast cancer.
Hyperbolic approximation of the BBM equation
Authors: Gavrilyuk Sergey , Shyue Keh-Ming
Published: February 2022

It is well known that the Benjamin–Bona–Mahony (BBM) equation can be seen as the Euler–Lagrange equation for a Lagrangian expressed in terms of the solution potential. We approximate the Lagrangian by a two-parameter family of Lagrangians depending on three potentials. The corresponding Euler–Lagrange equations can be then written as a hyperbolic system of conservations laws. The hyperbolic BBM system has two genuinely nonlinear eigenfields and one linear degenerate eigenfield. Moreover, it can be written in terms of Riemann invariants. Such an approach conserves the variational structure of the BBM equation and does not introduce the dissipation into the governing equations as it usually happens for the classical relaxation methods. The state-of-the-art numerical methods for hyperbolic conservation laws such as the Godunov-type methods are used for solving the ‘hyperbolized’ dispersive equations. We find good agreement between the corresponding solutions for the BBM equation and for its hyperbolic counterpart.
Insights into the growth of hexagonal Si crystals using Al-based nano absorber
Authors: Kim Kyoung Hwa , Lee Gang Seok , Ahn Hyung Soo , Lee Jae Hak , Kim Jongseok , Chun Young Tea , Yang Min , Yi Sam Nyung , Hwang Sun-Lyeong , Kim Suck-Whan
Published: February 2022

Although hexagonal (2H) silicon (Si) semiconductors exhibit excellent optical properties owing to their quasi-direct bandgap, their growth conditions, which require extremely high pressures, preclude their widespread use in industrial applications. The current study, therefore, proposes a novel approach for the facile growth of hexagonal Si at atmospheric pressure via a unique phenomenon known as Al-based nano absorber. A mixed-source hydride vapor phase epitaxy (HVPE) method was used for the growth of the hexagonal Si single crystals employing a rapid interaction between GaCl3, AlCl, and SiClngases at a high temperature of 1200 °C using a source mixture of Ga, Al, and Si. In this process, the Al-based nano absorber was formed, which resulted in the absorbance of Si atoms, rather than the growth of Al-based nano absorber, to form the Si crystals due to the subsequent lack of GaCl3and AlCl sources. The hexagonal Si structure of these Si crystals was confirmed using field emission scanning electron microscopy, high-resolution x-ray diffraction spectroscopy, and Raman spectroscopy. Thus, the current study establishes atmospheric pressure mixed-source HVPE as a facile approach for growing various allotropic crystals such as Si, C, or Ge via absorption of other atoms by an Al-based nano absorber.
Database of the effect of stabilizer on the resistivity and thermal conductivity of 20 different commercial REBCO tapes
Authors: Zhang Huimin , Suo Hongli , Wang Lei , Ma Lin , Liu Jianhua , Zhang Zili , Wang Qiuliang
Published: February 2022

The world’s first database on the effect of stabilizers on the resistivity and thermal conductivity of 20 different commercial REBa2Cu3O7−δ
(REBCO) tapes was established. The resistivity and thermal conductivity in the radial and circumferential directions were listed. The charging loss and self-protection ability of 20 different commercial REBCO tapes in the no-insulation coils were evaluated via simulation. By comparing and analyzing the data, the Cu/Ag interface was found to be the most probable primary factor determining the resistivity and thermal conductivity of REBCO tapes. Such a database can support abundant data for the design of the REBCO magnet or even the choice of REBCO switch or current lead. Another goal was to help the REBCO manufacturers find a feasible way to adjust the resistivity and thermal conductivity, thereby meeting different requirements of the REBCO magnet.
Minimal quantum thermal machine in a bandgap environment: non-Markovian features and anti-Zeno advantage
Authors: Xu Meng , Stockburger J T , Kurizki G , Ankerhold J
Published: February 2022

A minimal model of a quantum thermal machine is analyzed, where a driven two level working medium (WM) is embedded in an environment (reservoir) whose spectrum possesses bandgaps. The transition frequency of the WM is periodically modulated so as to be in alternating spectral overlap with hot or cold reservoirs whose spectra are separated by a bandgap. Approximate and exact treatments supported by analytical considerations yield a complete characterization of this thermal machine in the deep quantum domain. For slow to moderate modulation, the spectral response of the reservoirs is close to equilibrium, exhibiting sideband (Floquet) resonances in the heat currents and power output. In contrast, for faster modulation, strong-coupling and non-Markovian features give rise to correlations between the WM and the reservoirs and between the two reservoirs. Power boost of strictly quantum origin (‘quantum advantage’) is then found for both continuous and segmental fast modulation that leads to the anti-Zeno effect of enhanced spectral reservoir response. Such features cannot be captured by standard Markovian treatments.