bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermogravimetry of bentonite "navbahor" in nanocatalytic extraction technology and investigation of the convective ehfef drying process
Authors: Fayzullayev N. I. , Kurbonov J. M. , Kurbonova R. J. , Ishbaeva N. , Kurbonov J.J.
Published: August 2023

This study presents the results of a study of the process of thermography and convective drying of the retention substance bentonite used in the production of nanocatalysts based on Zol-gel technology. The study of the drying process using the energy of the convex-EHFEF EMF (extremely high-frequency electromagnetic field) in the preparation of a nanocatalystsfrom the retaining substance of bentonite is illuminated by the derivatogram of bentonite from the Navbahor deposit determined by the thermographic method. The determination of the porous structure and the comparable surface surface of the catalysts was carried out in an automatic gas adsorption analyzer using the Brunauer, Emmet, and Wyres (bet) method.The size and pore size of the catalysts were determined from data on desorption and adsorption isotherms, respectively, at a relative pressure R/R0=0.99 in accordance with the BJH (Barette-Joyner-Halend) model.
Based on the purpose of the work, the study of the drying process in the technology of obtaining a nan catalyst and the acceleration of its process and technology with its introduction into EHFEF (extremely high frequency electromagnetic field) EMC, was achieved to improve the quality of the porosity of catalysts. In particular, the analysis of the results obtained on the experimental scheme of the grooved-convex drying device, textural descriptions of bentonite of the Navbahor deposit, determined on the basis of standard techniques, porosity of the sample by the method of temperature nitrogen adsorption is presented.
Study of thickening polymeric compositions for printing fabric of blended fibers
Authors: Eshdavlatova G. E. , Panjiyev A. X.
Published: August 2023

Thickening compositions of a new composition for printing mixed fabrics based on cotton and nitron fibers have been developed. The influence of the components of dampening compositions on the rheological properties of the composition depending on their concentration was studied. Established the development of a new composition of the thickening composition of its physico-chemical and rheological properties.
A Novel Technique of Antegrade Cerebral Perfusion in the Newborn with Critical Aortic Stenosis
Authors: Auer Christian , Mair Rudolf , Geiselseder Gertraud , Sames Eva , Buhl Peter , Gross Christoph
Published: August 2023

Various methods of cerebral protection have been used during such aortic arch operations as the Norwood Procedure and operations on the interrupted aortic arch in neonates and infants. Deep hypothermia with circulatory arrest is the most common technique, but has a limited safe period for circulatory arrest. Antegrade cerebral perfusion has been introduced to prolong this safe period. We reviewed our experience with antegrade cerebral perfusion during surgical repair, in a patient with hypoplastic left heart syndrom in stage 1 palliation.
A Versatile Extracorporeal Circuit for Use During Repair of Descending and Thoracoabdominal Aortic Aneurysms in High-Risk Patients with Cardiac and/or Pulmonary Dysfunction: A Novel Approach to a Significant Perfusion Management Dilemma
Authors: Edwards Jeff T. , Brown D. Mark , Worrall Neil K.
Published: August 2023

The incidence of ischemic complications associated with repair of descending and thoracoabdominal aortic aneurysms has been significantly reduced by the use of distal aortic perfusion with moderate hypothermia, cerebral spinal fluid drainage, and segmental sequential clamping techniques. However, because the maintenance of proximal perfusion, the adequacy of left heart bypass (LHB), and the ability to ventilate patients on only one lung are all dependent on ventricular and pulmonary function, high- risk patients with descending and/or thoracoabdominal aortic aneurysms in the presence of cardiopulmonary insufficiency or instability present a difficult challenge for the surgical team. Traditional closed LHB circuits become nonfunctional in the event of cardiac arrest or refractory arrhythmias that create hemodynamic instability and are unable to provide necessary pulmonary support if the patient fails to ventilate adequately on one lung during thoracotomy. Furthermore, converting a patient from closed LHB to traditional venoarterial cardiopulmonary bypass (CPB) is frequently difficult, especially when the perfusionist works without the benefit of extra personnel to assist during such crises. Consequently, a modified extracorporeal circuit was designed to provide closed LHB with desired therapeutic adjuncts while also satisfying the additional need for a rapid infusion device, a source of supplemental ventilation/oxygenation, and, if necessary, the ability to convert the patient to venoarterial CPB conveniently in the event of cardiac and/or pulmonary failure during surgery to repair descending and/or thoracoabdominal aortic aneurysms.
Impact of Left Ventricular Dysfunction on Outcome in Aortic Stenosis Patients After Aortic Valve Replacement
Authors: Cummings Chanda , Sistino Joseph J. , Smyre J. Todd , Bell Adell
Published: August 2023

Surgical treatment for aortic stenosis includes aortic valve replacement, which alleviates symptoms and increases longevity. The purpose of this study was to evaluate the prevalence of left ventricular dysfunction after aortic valve replacement. Left ventricular function was assessed by a retrospective review of preoperative and postoperative ejection fractions (EF) using echocardiography. The prevalence of left ventricular dysfunction after aortic valve replacement was 17.39% with an odds ratio of 4.37 for low preoperative EF. Despite advances in myocardial protection and cardiothoracic surgical care, preoperative EF remains a strong predictor of outcome in patients undergoing aortic valve replacement.
Extended Support With the Terumo BABY-RX™ Oxygenator
Authors: Deptula Joseph J. , Fogg Sherrie K. , Glogowski Kimberly R. , Fenton Kathleen N. , Duncan Kim F.
Published: August 2023

The Terumo Baby-RX™, a new-generation low prime oxygenator, recently has entered the perfusion market in North America. This oxygenator is designed exclusively for neonates and infants and has the smallest priming volume of any clinically available oxygenator. The BABY-RX™ also is treated with X Coating™, Terumo’s biocompatible, hydrophilic polymer surface coating that reduces platelet adhesion and protein denaturation. The oxygenator has a blood flow range of 0.1 to 1500 mL/min and operates with a minimum reservoir volume of 15 mL. A 3.2-kg patient, status post-Stage 1 Norwood, Palliation was placed on cardiopulmonary support after thrombus formation within the modified Blalock-Taussig shunt during a general surgery procedure. The extended support circuit incorporated the Baby-RX™ oxygenator for 17.5 hours. The oxygenator performed well over this time period at flows of 600–800 mL/min, sweep rates of 100–300 mL/min, FiO2 of 30–40%, and ACTs of 140–200 seconds. There were no indices of oxygenator failure noted within the time frame of support. After placement of a new systemic to pulmonary shunt, the patient was removed from support and the oxygenator drained of residual blood. No evidence of fiber damage or clot formation was noted. The patient had a successful support run without complications related to cardiopulmonary support.
Conjugate Addition of Organoboron Compounds to α,β-Unsaturated Ketones Catalyzed by Nickelacycles
Authors: Semba Kazuhiko , Nakao Yoshiaki , Nagase Kotaro
Published: August 2023

The catalytic activity of nickelacycles in the conjugate addition of arylboronates to α,β-unsaturated ketones was investigated. Nickelacycles afforded β-arylated ketones in moderate to high yields, whereas an analogous palladacycle did not catalyze the reaction. Studies on the time course of the reaction confirmed that the nickelacycles act as active species in the conjugate addition reaction.
Homoeopathic Treatment of Postnatal Stage IV Pressure Ulcer: A Case Report
Authors: Singh Namrata , Das Kapil
Published: August 2023

Pressure ulcer or decubitus ulcer is generally caused due to constant pressure on the dependent parts of the body owing to impaired blood circulation. Due to this condition, the affected area shows varying changes from disruption of normal skin texture to formation of ulcer, many a times with discharge. Very commonly seen in cases with restricted ambulatory functions and /or immunodeficiency, pressure ulcers become a nuisance if left unattended. A case of a 28-year-old female patient presented with stage IV decubitus ulcers on her right gluteal region since the delivery of her 6 month old child. She had complaints of stinging or splinter like pain and itching of affected area with discharge of offensive pus worsening at night and with slightest touch. On the basis of totality, Acidum nitricum 200 was given, which provided a very favourable result in terms of healing the ulcer and progressing the state to a healthier one within 3 months. The outcome assessment in this case report was done by using the ‘MONARCH Inventory’.
Reporting Quality of the Abstracts for Randomized Controlled Trials in Pediatric Dentistry
Authors: Gopinath Vellore Kannan , Shetty Raghavendra M. , Renugalakshmi Apathsakayan , Dharmarajan Lalli , Prakash Ponnudurai Samuel Gnana , Jayaraman Jayakumar
Published: August 2023

Objectives The purpose of this study is to systematically appraise the reporting quality of abstracts for randomized controlled trials (RCT) published in pediatric dentistry using Consolidated Standards of Reporting Trials (CONSORT) for abstracts and to analyze the relationship between the characteristics of the RCT to the quality of abstracts.

Materials and Methods RCTs published in Pediatric Dentistry were retrieved from the PubMed database from 2016 to 2021. The quality of abstracts was appraised using CONSORT for abstracts checklist by two independent reviewers.

Statistical Analysis In descriptive statistics, frequency and percentage analysis were used for categorical variables, whereas mean and standard deviation were used for continuous variables. To find the significant difference between the bivariate samples in independent groups, Mann–Whitney U test was employed. Multivariate analysis was performed using Kruskal–Wallis test and Mann–Whitney U tests. Probability value of p-value less than 0.05 was considered as statistically significant.

Results Two hundred abstracts were included in the study. All the abstracts adequately reported the “objective” item, whereas only 2 and 4% of abstracts adequately addressed “randomization” and “harms” items, respectively. A significant relationship was observed between the continent of first author/corresponding author, number of authors, impact factor, adherence to CONSORT guidelines, word count, focus of study, and a
priori protocol registration to the quality of abstracts (p < 0.05).

Conclusion The abstracts of the RCT included in the study did not adequately follow the CONSORT for abstract guidelines. Adherence to the reporting guidelines would improve the overall reporting quality of abstracts of RCT published in Pediatric Dentistry. The overall mean score of the abstracts was 6.80 out of 15 indicating that the abstracts did not adequately follow the CONSORT for abstract reporting guidelines.
Life-Threatening Streptococcal Soft Tissue Infections in Children with Chickenpox: A Post-COVID-19 Case Series
Authors: McKechnie Iona , Mishra Ankit , Torres-Grau Jana , Cohen Jonathan , Filson Simon
Published: August 2023

Objective Children with chickenpox complicated by soft tissue infections can become critically unwell. We investigated cases that were referred to our center to examine the role of medical and surgical management in their care.

Methods Children presenting with severe soft tissue infections (SSTIs) associated with varicella infections to a tertiary children's hospital in London serving the South East of England were identified. A retrospective review of the patients' records was performed.

Results Ten patients presented having developed severe fever and localized cellulitis at around day 4 of their varicella infection. Group A Streptococcus (GAS) was identified as the causative organism in 90% of cases. Every patient required surgical intervention in addition to medical therapy to establish control of their soft tissue infection. We report 100% survival, and no patients required further reconstructive surgery.

Conclusion SSTIs, often caused by invasive GAS, can severely complicate otherwise innocuous cases of chickenpox. Failure to respond to maximal medical therapy should prompt urgent referral to a specialist center, and early surgical intervention can prevent progression to more serious illness.
Evaluation of SARS-CoV-2 Mother-to-Child Vertical Transmission: Prospective and Observational Study
Authors: Divarci Alper , Bulbul Ali , Bas Evrim Kiray , Yigitler Gulen Hurkal , Aydin Alev , Avsar Hasan , Congur Emel Celebi , Uslu Hasan Sinan , Unal Ebru Turkoglu
Published: August 2023

Objective The COVID-19 pandemic was declared a pandemic and a global health emergency by the World Health Organization (WHO) on March 11, 2020. COVID-19 infection is the most common cause of life-threatening acute respiratory tract infection in adults and older people but more mildly in the childhood age group. While the pandemic continues, there is no clear information about the vertical transmission of COVID-19 infection from the mother to the baby.

Methods In our study, we aimed to examine vertical virus transmission (breast milk, amniotic fluid, placenta) in pregnant women with COVID-19 infection and to examine the demographic, clinical, and laboratory characteristics of these infants. Our prospective and observational study was conducted in our hospital between March 1, 2020 and July 31, 2021.

Results During the study period, a total of 24 infants were included. All infants were admitted to the neonatal intensive care unit for postnatal follow-up. The virus was not detected in breast milk or amniotic fluids by the SARS-COV-2 reverse transcription polymerase chain reaction (RT-PCR) test, and no evidence of vertical transmission was found.

Conclusion In our study, no life-threatening complication was found in the babies of mothers infected with COVID-19 at birth. Babies born to mothers with COVID-19 infection did not develop any system findings that required specific treatment.
Second Wave of SARS-CoV-2: Impact on Pregnant Women and Newborns–A Tertiary Care Experience in North India
Authors: Bachani Sumitra , Suri Jyotsna , Kumar Anita , Dasgupta Suchandana , Dabral Anjali
Published: August 2023

Objectives

The aim of this study was to evaluate the clinical presentation, course of disease, and management of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in pregnant women. We also aimed to evaluate the fetomaternal outcomes in these women.

Material and Methodology

This was a single-center, retrospective study performed in a tertiary care hospital for pregnant women with coronavirus disease 2019 (COVID-19) in India. The medical records of all antenatal or postnatal women who were admitted to COVID-19 facility from April 1 to June 30, 2021, were reviewed. The demographic characteristics, obstetric parameters, presence of comorbidities, disease severity, investigations, management, and fetal outcome were recorded.

Statistical Analysis

The data were entered in MS Excel spreadsheet and analysis was done using Statistical Package for Social Sciences (SPSS) version 21.0.

Result

A total of 94 women were admitted to the COVID-19 facility; 54 (57.45%) were antenatal and 40 (42.55%) were postnatal, 75.53% of them were between 20 and 30 years of age, and 62.96% were multigravida. In addition, 42.55% were asymptomatic and 32.98, 9.58, and 14.89% had mild, moderate, and severe disease, respectively. Also, 42.59% of women had cesarean delivery. Among these, 14 (14.89%) required intensive care unit (ICU) admission, and 24.46% needed oxygen therapy. Comorbidities were present in 48.94%, with hypertensive disorder being the most common (14.89%). Common residual complaints were malaise, body ache, and cough. Among women admitted in the ICU, eight (57%) had comorbidities such as preeclampsia, diabetes, heart disease, and anemia. All these women required oxygen therapy, antibiotics, and thromboprophylaxis. Six among them received steroid (methylprednisolone) and four received antiviral drug (remdesivir). Three women succumbed to death. The mortality rate was 3.19%. Among the neonates, six babies were affected with SARS-CoV-2 and all recovered. On follow-up after discharge, one woman with rheumatic heart disease expired after 2 days of discharge and one woman had a spontaneous abortion.

Conclusion

During the second wave, caused by the Delta variant, maximum requirement was for oxygen therapy, antiviral drugs, and steroids. We conclude that women with comorbidities and advanced period of gestation had a severe course and required critical care. The optimum care and counselling regarding possible outcome in such a vulnerable population is needed.
A study of a slim compact piezo inertia actuator
Authors: Sun Pingping , Zhang Haozhen , Yu Huan
Published: August 2023

Most previously reported inertia actuators suffer from the problems of low speed and large size. To overcome these shortcomings, this study proposes a slim compact piezo inertia actuator based on the principle of stick–slip drive. Actuated by the transverse motion of a cantilever beam forming part of a monolithic elastomer, this actuator achieves a high velocity. The construction and basic operating principle of the actuator are discussed in detail. Commercial finite element analysis software is employed to determine the appropriate geometry for the monolithic elastomer. To study the actuator’s mechanical characteristics, a prototype is fabricated and a series of experimental tests are performed. According to the results of these tests, the maximum velocity and maximum load force are about 24.03 mm/s and 1.96 N, respectively, and the minimum step size is about 0.47 μm. It is shown that the inertia actuator based on a monolithic elastomer with a cantilever beam not only has a slim compact structure, but also exhibits good output characteristics.
Effects of laser energy on the surface quality and properties of electrodeposited zinc-nickel-molybdenum coatings
Authors: Ni Tao , Zhang Zhaoyang , Wu Yucheng , Yang Shuai
Published: August 2023

As a substitute for toxic cadmium coatings in the aerospace industry, zinc-nickel coatings have excellent application prospects, and their properties can be improved by adding molybdenum. In this study, laser-assisted electrodeposition is used to improve the surface quality and properties of Zn–Ni–Mo coatings, with investigation of how laser energy in the range of 0–21.1 μJ affects their element content, surface morphology, crystal phase, microhardness, residual internal stress, and corrosion resistance. The laser irradiation accelerates the electrodeposition, refines the grain size, improves the hydrogen adsorption, and reduces the residual tensile stress, and a laser energy of 15.4 μJ gives the highest Ni and Mo contents and the lowest Zn content, as well as the optimum surface morphology, microhardness, residual internal stress, and corrosion resistance of the coating.
An optical tweezer-based microdroplet imaging technology
Authors: Zhai Cong , Hong Yujian , Lin Zuzeng , Chen Yulu , Wang Han , Guo Tong , Hu Chunguang
Published: August 2023

Microspheres can break the diffraction limit and magnify nano-structure imaging, and with its advantages of low cost and label-free operation, microsphere-assisted imaging has become an irreplaceable tool in the life sciences and for precision measurements. However, the tiny size and limited imaging field of traditional solid microspheres cause difficulties when imaging large sample areas. Alternatively, droplets have similar properties to those of microspheres, with large surface curvature and refractive-index difference from the surrounding environment, and they can also serve as lenses to focus light for observation and imaging. Previous work has shown that droplets with controllable size can be generated using an optical tweezer system and can be driven by optical traps to move precisely like solid microspheres. Here, a novel microdroplet-assisted imaging technology based on optical tweezers is proposed that better integrates the generation, manipulation, and utilization of droplets.
Revealing the microscopic origin of static electricity
Authors: Lim Alane
Published: August 2023

Recent advances in triboelectricity provide an explanation for the common, but enigmatic, phenomenon.
Gamma-ray measurements for inertial confinement fusion
applications
Authors: Kim Yongho , Herrmann Hans W.
Published: August 2023

High-energy γ rays generated from inertial confinement fusion (ICF) experiments have become an important signature for studying the dynamics of implosion processes. Due to their high-energy and penetrating nature, γ rays are the most unperturbed fusion products, which can preserve the original birth information of the fusion process. Fusion γ rays provide a direct measure of nuclear reaction rates (unlike x rays) without being compromised by Doppler spreading (unlike neutrons). However, unambiguous γ-ray measurements for ICF study further required a decade-long period of technological development, which included a deepening understanding of fusion γ-ray characteristics and innovations in instrument performance. This review article introduces the production mechanism of the prompt and secondary γ rays and various ICF performance parameters (e.g., bang time and burn width), which can be derived from γ-ray measurement. A technical overview will be followed by summarizing γ-ray detectors fielded or proposed, especially for high-yield ICF experiments at the Omega Laser Facility and National Ignition Facility. Over the past few years, γ-ray diagnostic technologies have been extended beyond ICF research. A few examples of non-ICF applications of γ-ray detectors are introduced at the end of this article.
Numerical simulation of hypersonic plasma flow field disturbed by pulsed discharge
Authors: Luo Cheng , Liu Yanming , Zhang Jia , Yang Min
Published: August 2023

A plasma sheath will be generated around the hypersonic vehicle during reentry, and a large number of electrons in the plasma sheath will seriously affect the communication between the vehicle and the ground station. In order to reduce the electron number density of the hypersonic vehicle plasma sheath, a method of using pulsed discharge active actuation to regulate the plasma sheath is proposed. Based on the air dissociation and ionization model including 11 components and 32 chemical reactions, the reduction effect of pulsed discharge actuation on the electron density of plasma sheath is studied by numerical simulation. A first test is performed in which the pulsed discharge is compared with the plasma jets' experimental data. Then, a second test compared the plasma flow field around the RAMC-II vehicle with the flight test and NASA data. In these two tests, the simulation results are basically consistent with the experimental results. Finally, the effect of pulsed discharge with different energy density on the plasma sheath electron density is studied. The numerical results show that the interaction between the high-pressure aerodynamic actuation generated by the actuator and the plasma sheath produces an obvious shock wave, which blocks electrons from flowing downstream, reduces the velocity and pressure of the flow field behind the shock wave, and, finally, makes the electron density downstream of the actuator attenuate significantly, with the maximum attenuation amplitude of about 35%. Compared with the traditional method, the method proposed in this paper requires less space, load, and source power and has certain engineering feasibility.
Thickness-dependent flexoresistance in SrTiO3 thin films
Authors: Zhu Liwen , Liang Renhong , Ye Mao , Shu Longlong , Zheng Renkui , Ke Shanming
Published: August 2023

We report a thickness-dependent flexoresistance effect caused by strain gradient in SrTiO3 (STO) epitaxial thin films. The strain gradient in STO was induced by using an atomic force microscope diamond-coated tip. The depolarization field caused by the strain gradient changes the electrical state of the film, resulting in a decrease in the resistance of the films by 4–6 orders of magnitude. By testing the current–voltage (I–V) curves of STO films with different thicknesses, it is found that the flexoresistance behavior of STO films is obvious thickness dependent: the thicker the film, the higher the force threshold to trigger the film to enter a highly conductive state. The comparison of the surface morphology before and after the I–V test with loading shows that only when the thickness of the STO film is below 8 nm, the film can enter the conductive state from the insulating state without damaging the surface. During the electrical state switching process, the strain gradient caused by tip loading play an important role in the modification of the film barrier.
Sensitivity extension of atom-based amplitude-modulation microwave electrometry via high Rydberg states
Authors: Cai Minghao , You Shuhang , Zhang Shanshan , Xu Zishan , Liu Hongping
Published: August 2023

The Rydberg atom-based microwave electric field sensor has high sensitivity for weak RF-field detection. Selection of Rydberg states with larger electric dipole moment is beneficial to enhance the sensitivity, and we choose Rydberg states with its principal quantum number up to n ∼ 80. We study the probe laser transmission response to a microwave field for these chosen high Rydberg states at room temperature. It agrees well with theoretical simulation based on an optical Bloch equation with considered microwave-atom interaction and Doppler broadening effect. In our experiment, the microwave sensing sensitivity based on 85 Rb transition | 78 S 1 / 2 ⟩ → | 78 P 3 / 2 ⟩ arrives at 5.102(49) nV   cm − 1   Hz − 1 / 2 at 1 kHz.
Low-voltage, solution-processed InZnO thin-film transistors with enhanced performance achieved by bilayer gate dielectrics
Authors: Li Mengchao , Zhuang Qixin , Lu Shirong , Zang Zhigang , Cai Wensi
Published: August 2023

Fully solution-processed oxide thin-film transistors (TFTs) have shown a great potential in future printable electronics. However, high defect densities at the dielectric/channel interface have limited the simultaneous achievement of low operating voltage and high device performance. In this Letter, we study the effects of bilayer gate dielectrics in potential performance enhancement of solution-processed indium zinc oxide (IZO) TFTs. Several single and bilayer gate dielectrics are studied in terms of their physical and electrical properties. Compared with IZO TFTs using single-layer ZrOx gate dielectrics, optimized TFTs with ZrOx/AlOx gate dielectrics show an increase in carrier mobility and current on/off ratio by a factor of 3.5 and 27, respectively. The inner mechanisms of the performance enhancement are systematically studied, showing that the significantly improved TFT performance originates from the passivation effects of AlOx, which reduce the trap/defect states at the dielectric/channel interface by approximately an order of magnitude. With a low operating voltage of 2 V, a high mobility of over 10 cm2/V s, a subthreshold swing as low as 89 mV/dec, and a high current on/off ratio of >105, the reported devices might have a great potential in future low-cost, low-power printable electronics.
Acoustic properties, elasticity, and equation of state of glycerol under pressure
Authors: Vallero Cade , Ahart Muhtar , Tkachev Sergey , Chariton Stella , Prakapenka Vitali , Kojima Seiji , Gramsch Stephen A. , Hemley Russell J.
Published: August 2023

We employed high-pressure Brillouin scattering to study the pressure dependencies of acoustic modes of glycerol up to 14 GPa at 300 K. We observed longitudinal acoustic velocities and transverse acoustic velocities for the first time from 5 to 14 GPa. The results allow the determination of a complete set of elastic properties and an accurate determination of the pressure–volume (P–V) equation of state (EOS). EOS parameters, K0 = 14.9 ± 1.8 GPa and K′0 = 5.6 ± 0.5, were determined from fits to the data from ambient pressure to 14 GPa. Direct volume measurements of the P–V EOS are consistent with those determined by Brillouin scattering. A deviation from a Cauchy-like relationship for elastic properties was observed, and the pressure dependencies of the photoelastic constants and relaxation times were documented from 5 to 14 GPa. These results have broad implications for glass-forming liquids, viscoelastic theory, and mode coupling theory.
Review of Scientific Instruments New Products
Authors: Mandelis Andreas
Published: August 2023

In order to supplement manufacturers’ information, this department will welcome the submission by our readers of brief communications reporting measurements on the physical properties of materials which supersede earlier data or suggest new research applications.
Two-dimensional perovskite heterostructures for single crystal semiconductor devices
Authors: Park Jee Yung , Lee Yoon Ho , Kim Hyojung , Dou Letian
Published: August 2023

Two-dimensional (2D) perovskites have gained much attention lately owing to their excellent optoelectronic properties, chemical tunability, and environmental stability. Multiple methods have been devised to synthesize high quality 2D perovskite single crystals, and recent progress in fabricating its heterostructures is notable as well. In particular, with growing interest in 2D van der Waals heterostructures, 2D perovskites have become a strong candidate as a new building block for heterostructures to reveal unique physical properties across different interfaces. Until now, various heterostructure devices of 2D perovskite single crystals with other types of 2D materials such as transition metal dichalcogenides (TMDs) and graphene have been studied, which have shown intriguing results including interlayer excitons and enhanced electronic properties. Here, we introduce various synthetic approaches to realize 2D perovskite single crystals and unique characteristics of their single crystal heterostructures fabricated with precision, possessing sharp interfaces. Moreover, recent studies of semiconductor devices based on 2D perovskite single crystal heterostructures are discussed in-depth. New perspectives to further the horizon in the field of 2D perovskite heterostructures are suggested in this work including the consideration of metal–2D material van der Waals contact, application of dry transfer techniques, electric bias driven ion diffusion studies, and nanocrystal array fabrication. 2D perovskite heterostructure single crystal devices factoring in these novel perspectives will further uncover the true potential of these materials for highly efficient and stable semiconductor devices.
Spin polarization gate device based on the chirality-induced spin selectivity and robust nonlocal spin polarization
Authors: Shishido Hiroaki , Hosaka Yuta , Monden Kenta , Inui Akito , Sayo Taisei , Kousaka Yusuke , Togawa Yoshihiko
Published: August 2023

Nonlocal spin polarization phenomena are thoroughly investigated in the devices made of chiral metallic single crystals of CrNb3S6 and NbSi2 as well as of polycrystalline NbSi2. We demonstrate that simultaneous injection of charge currents in the opposite ends of the device with the nonlocal setup induces the switching behavior of spin polarization in a controllable manner. Such a nonlocal spin polarization appears regardless of the difference in the materials and device dimensions, implying that the current injection in the nonlocal configuration splits spin-dependent chemical potentials throughout the chiral crystal even though the current is injected into only a part of the crystal. We show that the proposed model of the spin dependent chemical potentials explains the experimental data successfully. The nonlocal double-injection device may offer significant potential to control the spin polarization to large areas because of the nature of long-range nonlocal spin polarization in chiral materials.
The central dogma of biological homochirality: How does chiral information propagate in a prebiotic network?
Authors: Ozturk S. Furkan , Sasselov Dimitar D. , Sutherland John D.
Published: August 2023

Biological systems are homochiral, raising the question of how a racemic mixture of prebiotically synthesized biomolecules could attain a homochiral state at the network level. Based on our recent results, we aim to address a related question of how chiral information might have flowed in a prebiotic network. Utilizing the crystallization properties of the central ribonucleic acid (RNA) precursor known as ribose-aminooxazoline (RAO), we showed that its homochiral crystals can be obtained from its fully racemic solution on a magnetic mineral surface due to the chiral-induced spin selectivity (CISS) effect [Ozturk et al., arXiv:2303.01394 (2023)]. Moreover, we uncovered a mechanism facilitated by the CISS effect through which chiral molecules, such as RAO, can uniformly magnetize such surfaces in a variety of planetary environments in a persistent manner [Ozturk et al., arXiv:2304.09095 (2023)]. All this is very tantalizing because recent experiments with tRNA analogs demonstrate high stereoselectivity in the attachment of L-amino acids to D-ribonucleotides, enabling the transfer of homochirality from RNA to peptides [Wu et al., J. Am. Chem. Soc. 143, 11836 (2021)]. Therefore, the biological homochirality problem may be reduced to ensuring that a single common RNA precursor (e.g., RAO) can be made homochiral. The emergence of homochirality at RAO then allows for the chiral information to propagate through RNA, then to peptides, and ultimately through enantioselective catalysis to metabolites. This directionality of the chiral information flow parallels that of the central dogma of molecular biology—the unidirectional transfer of genetic information from nucleic acids to proteins [F. H. Crick, in Symposia of the Society for Experimental Biology, Number XII: The Biological Replication of Macromolecules, edited by F. K. Sanders (Cambridge University Press, Cambridge, 1958), pp. 138-163; and F. Crick, Nature 227, 561 (1970)].
Slow solvation dynamics beyond dielectric relaxation by three-pulse photon echo peak shift
Authors: Kim JunWoo , Shin Pyoungsik , Joo Taiha
Published: August 2023

The dynamics of a liquid and its coupling to a solute are crucial for a better understanding of chemical processes in the liquid phase. In isotropic and homogeneous solutions, the time-correlation function of a solute is expected to vanish over time due to the translational and diffusive motions of the solvent. The three-pulse photon echo peak shift (3PEPS) is a third-order nonlinear spectroscopy technique that records the time-correlation function of a solute molecule in a solution, including an offset (inhomogeneity). In this work, we utilized a diffractive optics-based 3PEPS apparatus to fully resolve the dynamics in liquids from femtoseconds to nanoseconds while varying the temperature in the range of 80–298 K and the probe solute molecules. Our observations reveal dynamics slower than the dielectric relaxation of n-alcohols, even at room temperature, consisting of a ∼0.5 ns time constant that persists below the melting points and a static component (offset) on a nanosecond timescale. Based on the experiments, we suggest that locally formed glass-like clusters in liquids can be responsible for the slow dynamics. Our results may provide new insights into the dynamics of liquids and related phenomena such as liquid-glass and liquid-liquid phase transitions.
Mapping the structural trends in zinc aluminosilicate glasses
Authors: Mendes Da Silva Rita , Zeidler Anita , Mohammadi Hesameddin , Gammond Lawrence V. D. , Girón Lange Esther , Youngman Randall E. , Aitken Bruce G. , Hannon Alex C. , Benmore Chris J. , Vaughan Gavin B. M. , Salmon Philip S.
Published: August 2023

The structure of zinc aluminosilicate glasses with the composition (ZnO)x(Al2O3)y(SiO2)1−x−y, where 0 ≤ x < 1, 0 ≤ y < 1, and x + y < 1, was investigated over a wide composition range by combining neutron and high-energy x-ray diffraction with 27Al magic angle spinning nuclear magnetic resonance spectroscopy. The results were interpreted using an analytical model for the composition-dependent structure in which the zinc ions do not act as network formers. Four-coordinated aluminum atoms were found to be in the majority for all the investigated glasses, with five-coordinated aluminum atoms as the main minority species. Mean Al–O bond distances of 1.764(5) and 1.855(5) Å were obtained for the four- and five-coordinated aluminum atoms, respectively. The coordination environment of zinc was not observed to be invariant. Instead, it is dependent on whether zinc plays a predominantly network-modifying or charge-compensating role and, therefore, varies systematically with the glass composition. The Zn–O coordination number and bond distance were found to be 4.36(9) and 2.00(1) Å, respectively, for the network-modifying role vs 5.96(10) and 2.08(1) Å, respectively, for the charge-compensating role. The more open coordination environment of the charge-compensator is related to an enhanced probability of zinc finding bridging oxygen atoms as nearest-neighbors, reflecting a change in the connectivity of the glass network comprising four-coordinated silicon and aluminum atoms as the alumina content is increased.
On the specialization of Gaussian basis sets for core-dependent properties
Authors: Ireland Robbie T. , McKemmish Laura K.
Published: August 2023

Despite the fact that most quantum chemistry basis sets are designed for accurately modeling valence chemistry, these general-purpose basis sets continue to be widely used to model core-dependent properties. Core-specialized basis sets are designed with specific features to accurately represent the behavior of the core region. This design typically incorporates Gaussian primitives with higher exponents to capture core behavior effectively, as well as some decontraction of basis functions to provide flexibility in describing the core electronic wave function. The highest Gaussian exponent and the degree of contraction for both s- and p-basis functions effectively characterize these design aspects. In this study, we compare the design and performance of general-purpose basis sets against several literature-based basis sets specifically designed for three core-dependent properties: J coupling constants, hyperfine coupling constants, and magnetic shielding constants (used for calculating chemical shifts). Our findings consistently demonstrate a significant reduction in error when employing core-specialized basis sets, often at a marginal increase in computational cost compared to the popular 6-31G** basis set. Notably, for expedient calculations of J coupling, hyperfine coupling, and magnetic shielding constants, we recommend the use of the pcJ-1, EPR-II, and pcSseg-1 basis sets, respectively. For higher accuracy, the pcJ-2, EPR-III, and pcSseg-2 basis sets are recommended.
The slow magnetic relaxation in Dy-phthalocyanine single-molecule magnet induced by CH2Cl2 solvent molecules
Authors: Ruan Liuxia , Tong Junwei , Yang Wenzhen , Tian Fubo , Zhang Xianmin
Published: August 2023

DyPc2 and DyPc2•CH2Cl2 were prepared using the solvent thermal method. The x-ray diffractometer and the Fourier transform infrared spectrometer were used to explore the structure changes between DyPc2 and DyPc2•CH2Cl2. The results clearly demonstrate that the CH2Cl2 molecule can alter the crystal structures and, thus, change the molecular stacking structures of DyPc2 without destroying molecular integrity. Geometry optimization further proved that DyPc2 belongs to the space group P212121, while DyPc2•CH2Cl2 crystallizes in the space group Pnma. It is clearly demonstrated that the different molecular environment affects the structure of a single DyPc2 molecule to some extent, such as the twist angles of two Pc rings and the Pc−Dy−Pc angles. The molar magnetic susceptibility and hysteresis loops for DyPc2 and DyPc2•CH2Cl2 were also measured and compared. The negative Weiss constants were obtained by the Curie−Weiss law fitting above 50 K. The hysteresis loop for DyPc2•CH2Cl2 is wider than that of DyPc2, implying that the magnetic relaxation of DyPc2 slowed down, while quantum tunneling of the magnetization is prevented efficiently after absorbing CH2Cl2 molecules. This work clarifies the correlation between the molecular environment and magnetism of single-molecule magnets, which is helpful for their design guideline and future applications.
A novel diagnostic for dust particle size in a low-pressure nanodusty plasma based on the decay of the electron density released by laser-induced photodetachment
Authors: Donders T. J. M. , Staps T. J. A. , Beckers J.
Published: August 2023

One of the key parameters in low-pressure nanodusty plasmas is the dust particle size. In this work, we introduce a new method for the determination of the dust particle size in a nanodusty plasma, created in a mixture of argon and hexamethyldisiloxane. To this end, an ultraviolet (λ=266 nm) pulsed laser was used to release plasma-collected electrons from the nanoparticles. Subsequently, the response of the free electron density of the plasma was measured using microwave cavity resonance spectroscopy. Using a stochastic model for particle charging using orbital-motion limited (OML) theory, the predicted charging timescale can be directly compared to the experimentally measured decay timescale of the photo-released electron density. Good agreement was found between the experimentally predicted dust particle size and ex situ scanning electron microscopy (SEM) measurements. Furthermore, the sensitivity of the OML model to its input parameters was assessed. Finally, reversing the method can yield an estimate for the positive ion density based on the dust particle size from SEM.
Wave scattering by porous cylinders with inner columns near a vertical wall
Authors: Li Ai-jun , Liu Yong , Fang Hui
Published: August 2023

This paper studies wave scattering by multiple dual porous circular cylinders in front of a vertical wall. Each cylinder is composed of an outer partially perforated cylindrical shell and an inner impermeable column, and a circular wave-absorbing chamber is formed by the shell and column. An analytical solution to the hydrodynamic problem is developed in the context of potential flow theory. In the solving procedure, the hydrodynamic problem is transformed into an equivalent problem in an open water domain by using the image principle. The whole fluid domain in the equivalent problem is divided into multiple regions, and the velocity potential of the fluid motion in each region is expressed as the Fourier–Bessel series. The effect of the perforated shell on wave motion is considered through a pressure loss condition. The unknown coefficients in the velocity potential are determined by the transmission conditions on the boundaries between adjacent regions. The wave force, wave run-up on the porous cylinders, and the surface elevation near the cylinders are calculated. The analytical results are consistent with published results in several limiting cases. Typical cases are presented to clarify the characteristics of the wave force and wave run-up on the cylinders and discuss the effects of the wall and hydrodynamic interference on the hydrodynamic quantities. Moreover, several feasible applications of dual porous cylinders are discussed by visualizing the distribution of wave amplitude near the structures, and some valuable results are given.
Tin oxide-polyaniline nanocomposite modified nickel foam for highly selective and sensitive detection of cholesterol in simulated blood serum samples
Authors: Singh Pratiksha , Sreekumar Anjali , Badhulika Sushmee
Published: August 2023

Cholesterol (CH) is a vital diagnostic marker for a variety of diseases, making its detection crucial in biological applications including clinical practice. In this work, we report the synthesis of tin oxide-polyaniline nanocomposite-modified nickel foam (SnO2-PANI/NF) for non-enzymatic detection of CH in simulated human blood serum. SnO2 was synthesized via the hydrothermal method, followed by the synthesis of SnO2-PANI nanocomposite through in situ chemical polymerization of aniline using ammonium persulfate as the oxidizing agent. Morphological studies display agglomerated SnO2-PANI, which possess diameters ranging from an average particle size of ∼50 to ∼500 nm, and the XRD analysis revealed the tetragonal structure of the SnO2-PANI nanocomposite. Optimization studies demonstrating the effect of pH and weight percentage are performed to improve the electrocatalytic performance of the sensor. The non-enzymatic SnO2-PANI/NF sensor exhibits a linear range of 1–100 μM with a sensitivity of 300 μA μM−1/cm−2 towards CH sensing and a low limit of detection of 0.25 μM (=3 S m−1). SnO2-PANI/NF facilitates the electrooxidation of CH to form cholestenone by accepting electrons generated during the reaction and transferring them to the nickel foam electrode via Fe (III)/Fe (IV) conversion, resulting in an increased electrochemical current response. The SnO2-PANI/NF sensor demonstrated excellent selectivity against interfering species such as Na+, Cl−, K+, glucose, ascorbic acid, and SO4
2−. The sensor successfully determined the concentration of CH in simulated blood serum samples, demonstrating SnO2-PANI as a potential platform for a variety of electrochemical-based bioanalytical applications.
Bayesian estimation in multivariate inter-laboratory studies with unknown covariance matrices
Authors: Bodnar Olha , Bodnar Taras
Published: August 2023

In the paper we present Bayesian inference procedures for the parameters of multivariate random effects model, which is used as a quantitative tool for performing multivariate key comparisons and multivariate inter-laboratory studies. The developed new approach does not require that the reported covariance matrices of participating laboratories are known and, as such, it can be used when they are estimated from the measurement results. The Bayesian inference procedures are based on samples generated from the derived posterior distribution when the Berger and Bernardo reference prior and the Jeffreys prior are assigned to the model parameter. Three numerical algorithms for the construction of Markov chains are provided and implemented in the CCAUV.V-K1 key comparisons. All three approaches yield similar Bayesian estimators with wider credible intervals when the Berger and Bernardo reference prior is used. Also, the Bayesian estimators for the elements of the inter-laboratory covariance matrix are larger under this prior than for the Jeffreys prior. Finally, the constructed joint credible sets for the components of the overall mean vector indicate the presence of linear dependence between them which cannot be captured when only univariate key comparisons are performed.