bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Quantum Chemistry: A Hammett‐inspired Fingerprinting of Substituent Effects
Authors: Sessa Francesco , Olsson Martina , Söderberg Fredrik , Wang Fang , Rahm Martin
Published: January 2021

The quantum mechanically calculable Q descriptor is shown to be a potent quantifier of chemical reactivity in complex molecules – it shows a strong correlation to experimentally derived field effects in non‐aromatic substrates and Hammett σm and σp parameters. Models for predicting substituent effects from Q are presented and applied, including on the elusive pentazolyl substituent. The presented approach enables fast computational estimation of substituent effects, and, in extension, medium‐throughput screening of molecules and compound design. An experimental dataset is suggested as a candidate benchmark for aiding the general development and comparison of electronic structure analyses. It is here used to evaluate the experimental quantum chemistry (EQC) framework for chemical bonding analysis in larger molecules.
Conformational Preferences of Cyclopentane‐Based Oligo‐δ‐peptides in the Gas Phase and in Solution
Authors: Park Hae Sook , Kang Young Kee
Published: January 2021

The conformational preferences of oligomers of δ‐amino acid (δAc5a) with a cyclopentyl constraint in the Cβ−Cγ bond of the backbone were investigated by using DFT methods in the gas phase and in solution. The folded structures with C10 H‐bonded pseudocycles were most preferred for dimer and tetramer of δAc5a residues both in chloroform and water. However, for the hexameric Ac‐(δAc5a)6‐NHMe, the mixed H16/14 helical structure was found to be most preferred in chloroform (populated at 68 %), whereas the H14 helical structure was the most dominant conformation in water (populated at 60 %). The stability of the former was ascribed to the intrinsic conformational energy, whereas the solvation free energy was crucial to stabilize the latter. Pyrrolidine‐substituted analogues of the hexameric Ac‐(δAc5a)6‐NHMe, with adjacent amine diads that are almost exactly one turn apart with two nitrogen atoms separated by ca. 5.5 Å, adopted helical structures. They are potential catalysts in nonpolar and polar solvents as they have similar structures to a helical 1 : 2 α:β‐heptapeptide that exhibited good catalytic performance in the crossed aldol condensation.
Match and mismatch: Integrating consumptive effects of predators, prey traits, and habitat selection in colonizing aquatic insects
Authors: Pintar Matthew R. , Resetarits William J.
Published: January 2021

Predators are a particularly critical component of habitat quality, as they affect survival, morphology, behavior, population size, and community structure through both consumptive and non‐consumptive effects. Non‐consumptive effects can often exceed consumptive effects, but their relative importance is undetermined in many systems. Our objective was to determine the consumptive and non‐consumptive effects of a predaceous aquatic insect,Notonecta irrorata, on colonizing aquatic beetles. We tested howN. irrorataaffected survival and habitat selection of colonizing aquatic beetles, how beetle traits contributed to their vulnerability to predation byN. irrorata, and how combined consumptive and non‐consumptive effects affected populations and community structure. Predation vulnerabilities ranged from 0% to 95% mortality, with size, swimming, and exoskeleton traits generating species‐specific vulnerabilities. Habitat selection ranged from predator avoidance to preferentially colonizing predator patches. Attraction of Dytiscidae toN. irroratamay be a natural ecological trap given similar cues produced by these taxa. Hence, species‐specific habitat selection by prey can be either predator‐avoidance responses that reduce consumptive effects, or responses that magnify predator effects.Notonecta irroratahad both strong consumptive and non‐consumptive effects on populations and communities, while combined effects predicted even more distinct communities and populations across patches with or without predators. Our results illustrate that an aquatic invertebrate predator can have functionally unique consumptive effects on prey, attracting and repelling prey, while prey have functionally unique responses to predators. Determining species‐specific consumptive and non‐consumptive effects is important to understand patterns of species diversity across landscapes.
Application of Bayesian networks in evaluation of current status and protection of Pulsatilla patens (L.) Mill.
Authors: Sienkiewicz Aneta , Łaska Grażyna
Published: January 2021

Understanding of the impact of environmental factors on endangered plant species provides a basis for assessment of the risk of their extinction in the near future. Of particular importance is the search for optimal environmental conditions to preserve the continued existence of endangered taxa. Thus, there is a need for a method based on mathematical modeling to connect the current status of an endangered plant species with changing environmental conditions. Using the basics of decision theory, we developed a mathematical model to assess the influence of changing habitat conditions on the current status and protection of Pulsatilla patens (L.) Mill., an endangered plant species in Europe, as an example. The mathematical model was based on the data from 43 sites in the 3 largest forest complexes in NE Poland from 2011 to 2014 (29 attributes, 1566 records). The graphical model showing significant cause‐and‐effect relations between morphological‐developmental features of individuals, demographic features of the populations, and physicochemical properties of the soil was built using the Bayesian networks in GeNIe 2.0 (University of Pittsburgh, Pittsburgh, Pennsylvania, USA). In the process of modeling with the Bayesian Search Algorithm, we also performed simulation, prediction, and optimization of the effects of selected environmental factors on growth and development of the endangered taxon. The diagnostic testing and sensitivity analysis revealed that the degree of soil acidification is the major variable determining the size of populations (number of individuals), developmental phase (juvenile, vegetative, flowering), and size of the individuals (height and diameter of ground rosette). Using the approach presented in this work, it was possible to identify a new habitat factor not known to be important at multiple scales for growth, development, and population dynamics of P. patens. The validation showed that the developed model is the most effective for evaluation of the impact of habitat conditions on the population features important for reproduction of this taxon. Therefore, the model proposed is recommended as a tool to support decision‐making aimed at conservation planning of the endangered plant species.
An Adaptive Resorcinarene Hemicarcerand
Authors: Danielsiek Dominic , Dyker Gerald
Published: January 2021

A new resorcinarene‐based hemicarcerand was developed, exhibiting pronounced flexibility in size and shape to accommodate several guest molecules. With a series of seven hemicarceplexes, investigated via single‐crystal XRD, the cage molecule showed to align its guests to complement their electrostatic potentials and to adjust its dimensions, according to the guest molecule‘s demand. Though forming equimolar inclusion complexes with most guests, crystallization from chloroform, and benzonitrile produced hemicarceplexes with a guest/host ratio of 2 : 1, exhibiting packing coefficients as high as 91 %. In competition experiments, the hemicarcerand clearly favors p‐xylene over m‐xylene: The host shows to crystallize, solely incarcerating p‐xylene from a 1 : 1 mixture of the two xylenes, and also isolates p‐xylene from the mixture via amorphous precipitation.
Effects of uniconazole on the physiological characteristics and cadmium accumulation of Cyphomandra betacea seedlings
Authors: Huang Kewen , Xiao Yunying , Dong Yiping , Xu Xiangting , Zhang Ran , Lin Lijin , Liao Ming'an
Published: January 2021

To determine if the uniconazole concentration(s) whether could enhance the cadmium (Cd) tolerance of Cyphomandra betacea seedlings, the effects of spray treatments with various uniconazole concentrations (0, 5, 10, 20, and 50 mg/L) on the physiological characteristics and Cd accumulation of C. betacea seedlings were studied in a hydroponic experiment. The results indicated that uniconazole significantly decreased the Cd content of C. betacea seedling stems, leaves, and shoots, but significantly increased the biomass of all analyzed seedling parts. Additionally, the leaf chlorophyll a, chlorophyll b, and carotenoid contents as well as the net photosynthetic rate, transpiration rate, stomatal conductance, and CO2 concentration of intercellular were higher for the uniconazole‐treated C. betacea seedlings than for the control seedlings. The optimal uniconazole concentration significantly promoted the superoxide dismutase, peroxidase, and catalase activities and the soluble protein content of C. betacea leaves. Moreover, uniconazole decreased the soluble sugar content of the C. betacea roots and stems, but had the opposite effect on the soluble sugar content of the leaves and shoots. The 20 mg/L uniconazole treatment resulted in the highest C. betacea seedling biomass and the lowest Cd content, indicating this concentration may be useful for improving C. betacea seedling growth in Cd‐contaminated soils.
Purinergic signaling in peripheral nervous system glial cells
Authors: Patritti‐Cram Jennifer , Coover Robert. A. , Jankowski Michael P. , Ratner Nancy
Published: January 2021

To facilitate analyses of purinergic signaling in peripheral nerve glia, we review recent literature and catalog purinergic receptor mRNA expression in cultured mouse Schwann cells (SCs). Purinergic signaling can decrease developmental SC proliferation, and promote SC differentiation. The purinergic receptors P2RY2 and P2RX7 are implicated in nerve development and in the ratio of Remak SCs to myelinating SCs in differentiated peripheral nerve. P2RY2, P2RX7, and other receptors are also implicated in peripheral neuropathies and SC tumors. In SC tumors lacking the tumor suppressor NF1, the SC pathway that suppresses SC growth through P2RY2‐driven β‐arrestin‐mediated AKT signaling is aberrant. SC‐released purinergic agonists acting through SC and/or neuronal purinergic receptors activate pain responses. In all these settings, purinergic receptor activation can result in calcium‐independent and calcium‐dependent release of SC ATP and UDP, growth factors, and cytokines that may contribute to disease and nerve repair. Thus, current research suggests that purinergic agonists and/or antagonists might have the potential to modulate peripheral glia function in development and in disease.
Multilayer flow and heat transport of nanoliquids with nonlinear Boussinesq approximation and viscous heating using differential transform method
Authors: Rajeev Anandika , Mahanthesh Basavarajappa
Published: January 2021

Multilayer fluid flow models are significant in various applications, namely, cooling electronic systems, solar thermal systems, and nuclear reactors. The density of a fluid fluctuates nonlinearly due to large temperature difference circumstances in thermal systems. Thus, the linear Boussinesq approximation is no longer relevant. Therefore, this article describes a multilayer flow of nanoliquids in the presence of nonlinear Boussinesq approximation. The hybrid nanoliquid layer is sandwiched between two nanoliquid layers. The single‐phase khanafer‐vafai‐lightstone model is implemented to simulate the nanoliquids. The quadratic density temperature fluctuation and viscous heating are taken into account. The temperature and velocity across the interface are assumed to be continuous. The equations that govern the problem are solved analytically by using the differential transformation method. The results show that the presence of a hybrid nanoliquid layer affects the velocity and heat transfer properties of the nanofluid flow. Hybrid nanofluid can be used to achieve the desired multilayer flow properties of a nanofluid and its heat transfer properties. Further, the quadratic convection aspect increases the velocity distributions.
Time‐dependent hydromagnetic stagnation point flow of a Maxwell nanofluid with melting heat effect and amended Fourier and Fick's laws
Authors: Bilal Muhammad , Mazhar Syeda Z. , Ramzan Muhammad , Mehmood Yasir
Published: January 2021

An unsteady stagnation point flow of a Maxwell fluid over a unidirectional linearly stretching sheet is studied under the influence of a magnetic field. The parabolic energy equation, which is based on parabolic Fourier law is replaced with a hyperbolic energy equation incorporating the heat flux model of Cattaneo–Christov. The Buongiorno model is used to characterize the properties of nanofluids using thermophoresis and Brownian diffusion coefficients. The phenomenon of melting heat transfer and slip mechanism is also embodied in the present study. Coupled nonlinear differential equations have appeared when the specified similarity transformations are applied. The mathematical problem is tackled via the homotopy analysis method. The impact of important physical parameters on the velocity, concentration, and temperature are highlighted via graphs. To verify our present results, a comparison is given with a limiting case with an already published article. It is witnessed through the graphs that the higher unsteadiness parameter and melting heat coefficient both are responsible for the reduction in the velocity and temperature of the nanofluid. Also, the velocity slip parameter detracts the velocity profile and affiliated boundary layer thickness of the Maxwell nanofluid.
Trade openness, financial development and economic growth in North African countries
Authors: Mohamed Sghaier Imen
Published: January 2021

This contribution investigates the relationships between financial development, trade openness and economic growth on a panel of four North African countries (Tunisia, Morocco, Algeria and Egypt), over a 5‐year period from 1991 to 2015. In fact, using the generalized method of moment (GMM) in a panel data analysis, we found strong evidence of a positive link between trade openness and economic growth. Moreover, we found that trade openness appears to be working as a complement to financial development and that its effect is more pronounced in the presence of the financial development variable. Therefore, the policy implications of this study appeared clear. Hence, improvement efforts need to be driven by local‐level reforms to ensure the development of domestic financial system and take full advantage of the technology transfer induced by international trade.
Associations of PER3 polymorphisms with clopidogrel resistance among Chinese Han people treated with clopidogrel
Authors: Zheng Nan , Yin Fengying , Yu Qinglin , Zhong Jinyan , Yang Jin , Xu Zhifeng , Su Jia , Chen Xiaomin
Published: January 2021

Background

Changes in circadian rhythm are related to various diseases, such as immune system diseases and cardiovascular diseases. The PERIOD3 (PER3) clock gene is one of the most important genes in the rhythm regulation system. Our goal was to evaluate the possible association between the PER3 rs228729 (T/C) polymorphism or PER3 rs2797685(T/C) polymorphism and clopidogrel resistance (CR) and to study the impact of clinical baseline data on clopidogrel resistance.

Methods

PER3 polymorphisms rs2797685 (T/C) and rs228729 (T/C) were assessed in 156 patients with (72) and without (84) CR. Blood samples were collected and analyzed after the application of clopidogrel for interventional therapy.

Results

Age, albumin, PLT, and PCT levels influenced the risk of CR (p < 0.05). For rs2797685, when the PCT value was greater than 0.19, patients with the TT + TC genotype had an increased risk of clopidogrel resistance compared with those with the CC genotype (PCT ≥ 0.19, p = 0.014; PCT p = 0.004). In patients with albumin values greater than 40 or PCT greater than 0.19, those with the rs228729 TT + TC genotype had an increased risk of clopidogrel resistance compared with those with the CC genotype (albumin≥40, TT+TC:CC, p = 0.01, albumin p = 0.005; PCT ≥ 0.19, TT+TC:CC, p < 0.001, PCT p = 0.004). Logistic regression analysis of clinical baseline data and genotype showed that high albumin is a protective factor against clopidogrel resistance. The PER3 gene polymorphism has no clear correlation with clopidogrel resistance.

Conclusion

In summary, our research shows that PER3 SNPs may be helpful to assess the pathogenesis of CR.
The value of women coming together: Effects and practices of a gender‐focused community intervention funded by a government agency
Authors: Daher Marianne , Cifuentes Sofía , Saa Madelaine , Rosati Antonia , Hernández Angie
Published: January 2021

The gender focus has been incorporated into public policies as a strategy to reduce gender inequity and overcome discriminatory stereotype behaviors. However, the state or institutional feminism has been questioned for being uncritical and not very transformative, where the critical and transformative nature of community psychology offer valuable opportunities. In this context, effects and practices of a community intervention funded by a government agency and aimed at the de‐naturalization of gender stereotypes and its consequences in everyday life with vulnerable women, mostly older adults, are analyzed. Using a qualitative methodology, interviews and focus groups with women who participated in the intervention, community leaders, and key actors were conducted. A total of 46 people took part in the investigation. Data were analyzed using Grounded Theory. Facilitating and hindering factors influencing the gender‐focused community intervention implemented were identified. Furthermore, effects linked to community participation among women are regarded as affirmative acts in response to social vulnerability, with self‐care, co‐care, and empowerment regarding gender stereotypes standing out as the main results. Finally, the value of women's gatherings in community spaces, linking them with the contributions of feminist theory, and outline points of tension and challenges facing gender‐focused community interventions are discussed.
Embryotoxicity characterization of the flame retardant tris(1‐chloro‐2‐propyl)phosphate (TCPP) in the invertebrate chordate Ciona intestinalis
Authors: Mercurio Silvia , Messinetti Silvia , Manenti Raoul , Ficetola Gentile Francesco , Pennati Roberta
Published: January 2021

Tris(1‐chloro‐2‐propyl)phosphate (TCPP) is the most common chlorinated organophosphorus flame retardant in seawater. Due to its chemical features and abundance, TCPP has been classified as a high hazard, and restrictions of use have been set in multiple countries. Despite TCPP being highly present in the marine environment, only a few studies have explored the TCPP impact on the development of marine invertebrates. Ascidians are important invertebrate members of benthic marine communities and reliable model systems for ecotoxicological research. The aim of this study was to assess the adverse effects of TCPP exposure on the embryogenesis of the ascidian Ciona intestinalis. Our results showed that this pollutant affected both muscles and nervous system development. Malformations appeared similar to those reported in other animal models for other flame retardants, suggesting that these molecules could share a common mechanism of action and induce a mixture effect when simultaneously present in the aquatic environment even at sub‐teratogenic concentrations.
The nonpharmacological sequence method provides a reliable evaluation of baroreflex sensitivity in fish
Authors: Armelin Vinicius A. , Braga Victor H. da Silva , Teixeira Mariana T. , Guagnoni Igor N. , Wang Tobias , Florindo Luiz H.
Published: January 2021

The most commonly used technique to study the barostatic regulation of blood pressure in ectothermic vertebrates consists of determining the heart rate response to pharmacological manipulations of blood pressure, the so‐called “Oxford method.” Although well established, the Oxford method has some important limitations, such as induction of hypervolemia in small animals and undesired effects of vasoactive drugs on central and peripheral baroreflex components. As an alternative, the sequence method, which consists in the computerized evaluation of naturally‐occurring baroreflex adjustments of heart rate without the need for pharmacological administrations, was developed to study baroreflexes. In the present study, we compare this sequence method with the Oxford technique in two teleost species with different life styles, and we assess the optimal software configuration for the employment of the sequence method in fish. Calculation of baroreflex gain through the sequence method was adequate and reliable when the software was configured to search for baroreflex sequences with a minimum length of three cardiac cycles with a delay of one cardiac cycle between fluctuations in mean ventral aortic blood pressure and reflex changes in pulse interval. When properly configured, the sequence and the Oxford methods yielded similar determinations of the baroreflex gain in fish.
In‐hospital mortality in gastroparesis population and its predictors: A United States‐based population study
Authors: Saleem Saad , Inayat Faisal , Aziz Muhammad , Then Eric O , Zafar Yousaf , Gaduputi Vinaya
Published: January 2021

Background and Aim

To determine the United States‐based in‐hospital gastroparesis mortality rate and independent predictors associated with it.

Methods

A retrospective study was conducted using the deidentified National Inpatient Sample and Healthcare Cost and Utilization Project database between the years 2012 and 2014. The in‐hospital gastroparesis mortality rate was calculated. Patients' demographics, including age, gender, race, comorbid conditions, and hospital characteristics, were examined as potential predictors of mortality.

Results

The gastroparesis mortality rate was 3.19 per 1000 gastroparesis patients for the years 2012–2014. Caucasians had the highest mortality rate, with odds ratio (OR) = 2.27; 95% confidence interval (CI) 1.52–3.38, and P = 0.0001. Rural hospitals had higher mortality, with OR = 1.51, 95% CI 1.10–2.10, and P = 0.01, whereas urban nonteaching and teaching hospitals showed no statistically significant mortality difference, with OR = 0.83, 95% CI 0.6–1.15, and P = 0.27 and OR = 0.82, 95% CI 0.59–1.15, and P = 0.25, respectively. In hospitals in the south region, mortality was the highest at 65.6%, with OR = 2.05, 95% CI 1.48–2.84, and P < 0.0001. Patients with diabetes mellitus had 39% lower probability in the mortality group.

Conclusion

Being of advanced age; being White; and being in a rural, southern U.S. hospital were predictors of in‐hospital mortality in gastroparesis patients.
Will the emergent SARS‐CoV2 B.1.1.7 lineage affect molecular diagnosis of COVID‐19?
Authors: Ramírez Juan D. , Muñoz Marina , Patiño Luz H. , Ballesteros Nathalia , Paniz‐Mondolfi Alberto
Published: January 2021

As the coronavirus disease 2019 pandemic keep tackling global public health systems worldwide. The severe acute respiratory syndrome coronavirus 2 (SARS‐CoV2) genome keeps mutating. In that regard, the recent emergence of the B.1.1.7 lineage in the UK has called the attention of global authorities. One point of concern is that if this lineage can be detected by traditional molecular schemes for SARS‐CoV‐2 detection. Herein, we showed that this lineage does not affect the Berlin–Charité protocol but can challenge the available commercial kits directed to the Spike (S) gene. All efforts should be made to continue to monitor SARS‐CoV‐2 genomes for potential variants that can impair diagnostic testing and lead to false negative results.
Raman spectroscopy analysis of graphene oxide‐enhanced textiles
Authors: Jin Huaizhou , Zhu Leilei , Jin Shangzhong , Jiang Li , Zou Yanqiu
Published: January 2021

Graphene oxide (GO) enhanced textiles were studied using Raman spectroscopy. Compared with regular textiles, GO‐enhanced textiles show GO's signature D and G peaks at 1,350 and 1,580 cm−1; they also show GO's harmonics peaks at 2,690 and 2,925 cm−1. The intensity of GO's signature peaks has linear correlation with GO's percentage in weight. A principal component analysis (PCA) and support vector machine (SVM) model are used to classify textile samples with 98.75% accuracy.
Concentrate supplementation with dried corn gluten feed improves the fatty acid profile of longissimus thoracis muscle from steers offered grass silage
Authors: Salami Saheed A , O'Grady Michael N , Luciano Giuseppe , Priolo Alessandro , McGee Mark , Moloney Aidan P , Kerry Joseph P
Published: January 2021

BACKGROUND

Concentrate supplementation of a grass silage‐based ration is a typical practice employed for indoor winter finishing of beef cattle in many temperate countries. Plant by‐products, such as dried corn gluten feed (CGF), can be used to replace conventional feedstuffs in a concentrate supplement to enhance the sustainability of ruminant production systems and to improve meat quality. This study examined the chemical composition, fatty acid profile, oxidative stability and sensory attributes of beef (longissimus thoracis muscle) from steers offered grass silage and concentrate supplements containing varying levels (0%, 25%, 50%, 75%) of CGF substituted for barley / soybean meal.

RESULTS

Feeding 50%CGF decreased the protein content and increased intramuscular fat in comparison with 25%CGF. Total phenol content and iron‐reducing antioxidant power followed the order: 0%CGF > 50%CGF and 25%CGF > 0%CGF = 50%CGF, respectively. Compared to 0%CGF, 25%CGF and 75%CGF decreased C14:0 and increased C22:2n‐6, C20:5n‐3 and total n‐3 polyunsaturated fatty acids whereas 75%CGF increased conjugated linoleic acids and C18:3n‐3. Diet did not affect the oxidative stability and sensory attributes of beef patties.

CONCLUSION

The inclusion of up to 75%CGF in a supplementary concentrate for steers increased the proportion of health‐promoting unsaturated fatty acids without negatively influencing the shelf‐life and eating quality of longissimus thoracis muscle. © 2021 Society of Chemical Industry
Dysphagia Evaluation: The Added Value of Concurrent MBS and Esophagram
Authors: Hawkins Daniel , Cabrera Claudia I. , Kominsky Rachel , Nahra Alexis , Howard N. Scott , Maronian Nicole
Published: January 2021

Objectives/Hypothesis

Dysphagia is associated with increased mortality and healthcare costs. The modified barium swallow study (MBS) is the gold standard in assessing oropharyngeal dysphagia, but does not evaluate the esophagus. A barium esophagram can visualize the esophagus but does not evaluate the oropharyngeal swallow, nor does it utilize the expertise of speech and language pathologists. Providers may order one or both studies yet still risk missing critical pathology.

Study Design

Retrospective cohort study.

Methods

A retrospective chart review was conducted at an academic medical center between January 2016 and June 2019 focused on patients who had both MBS and esophagram as imaging for dysphagia evaluation. Analysis determined whether MBS and esophagram performed concomitantly improved diagnostic clarity.

Results

A total of 5,183 patients underwent 6,066 swallow studies for dysphagia in the study period. Of which, 124 of these patients had concurrent MBS and esophagram. 10.5% of concurrent studies demonstrated a congruent negative evaluation. 59.7% of patients had an unremarkable MBS or esophagram paired with abnormal findings within the corresponding esophagram or MBS, respectively. 29.8% had both MBS and esophagrams that demonstrated an abnormality, but with unique pathologies identified by each study. In total, 85.1% of unremarkable MBS or esophagrams were paired with abnormal findings in the corresponding esophagram or MBS, respectively.

Conclusion

Selection of diagnostic testing is variable among providers and may be influenced by healthcare systems. This analysis revealed that MBS and esophagrams provide unique diagnoses. Concurrent MBS and esophagrams may improve diagnostic accuracy, yet minimize additional studies. National practices around dysphagia diagnostics are inconsistent and would benefit from standardization.

Level of Evidence

4 Laryngoscope, 131:2666–2670, 2021
First measurements of ionization cluster‐size distributions with a compact nanodosimeter
Authors: Vasi Fabiano , Schneider Uwe
Published: January 2021

Purpose

A nanodosimeter is a type of detector which measures single ionizations in a small gaseous volume in order to obtain ionization cluster size probability distributions for characterization of radiation types. Working nanodosimeter detectors are usually bulky machines which require a lot of space. In this work, the authors present a compact ceramic nanodosimeter detector and report on first measurements of cluster size distributions of 5 MeV alpha particles.

Methods

Single ionization measurements are achieved by applying a weak electric field to collect positive ions in a hole in a ceramic plate. Inside the ceramic plate, due to a strong electric field, the ions are accelerated and produce impact‐ionizations. The resulting electron avalanche is detected in a read‐out electrode. A Bayesian unfolding algorithm is then applied to the experimentally obtained cluster size distributions to reconstruct the true cluster size distributions.

Results

Experimentally obtained cluster size distributions by the compact nanodosimeter detector are presented. The reconstructed cluster size distributions agreed well with Monte Carlo simulated cluster size distributions for small volumes (diameter = 2.5 nm). For larger volumes, discrepancies between the reconstructed cluster size distributions and cluster size distributions from Monte Carlo simulations were observed.

Conclusions

For the first time, ionization cluster size probability distributions could be obtained by a small and compact nanodosimeter detector. This signifies the achievement of a critical step toward the wide application of nanodosimetric characterization of radiation types including in clinical environments.
Treatment planning system and beam data validation for the ZAP‐X: A novel self‐shielded stereotactic radiosurgery system
Authors: Srivastava Shiv P. , Jani Shyam S. , Pinnaduwage Dilini S. , Yan Xiangsheng , Rogers Leland , Barranco F. David , Barani Igor J. , Sorensen Stephen
Published: January 2021

Purpose

To evaluate the treatment planning system (TPS) performance of the ZAP‐X stereotactic radiosurgery (SRS) system through nondosimetric, dosimetric, and end‐to‐end (E2E) tests.

Methods

A comprehensive set of TPS commissioning and validation tests was developed using published guidelines. Nondosimetric validation tests included information transfer, computed tomography–magnetic resonance (CT‐MR) image registration, structure/contouring, geometry, dose tools, and CT density. Dosimetric validation included comparisons between TPS and water tank/Solid Water measurements for various geometries and beam arrangements and end‐to‐end (E2E) tests. Patient‐specific quality assurance was performed with an ion chamber in the Lucy phantom and with Gafchromic EBT3 film in the CyberKnife head phantom. RadCalc was used for independent verification of monitor units. Additional E2E tests were performed using the RPC Gamma Knife thermoluminescent dosimeter (TLD) phantom, MD Anderson SRS head phantom, and PseudoPatient gel phantom for independent absolute dose verification.

Results

CT‐MR image registrations with known translational and rotational offsets were within tolerance (<0.5 × maximum voxel dimension). Slice thickness and distance accuracy were within 0.1 mm, and volume accuracy was within 0 to 0.11 cm3. Treatment planning system volume measurement uncertainty was within 0.1 to 0.4 cm3. Ion chamber point‐dose measurements for a single beam in a water phantom agreed to TPS‐calculated values within ±4% for collimator diameters 10 to 25 mm, and ±6% for 7.5 mm, for all measured depths (7, 50, 100, 150, and 200 mm). In homogeneous Solid Water, point‐dose measurements agreed to within ±4% for cones sizes 7.5 to 25 mm. With 1‐cm high/low density inserts, measurements were within ±4.2% for cone sizes 10 to 25 mm. Film‐based E2E using 4/5‐mm cones resulted in a gamma passing rate (%GP) of 99.8% (2%/1.5 mm). Point‐dose measurements in a Lucy phantom with an ion chamber using 36 beams distributed along three noncoplanar arcs agreed to within ±4% for cone sizes 10 to 25 mm. The RPC Gamma Knife TLD phantom yielded passing results with a measured‐to‐expected TLD dose ratio of 1.02. The MD Anderson SRS head phantom yielded passing results, with 4% TLD agreement and %GP of 95%/93% (5%/3 mm) for coronal/sagittal film planes. The RTsafe gel phantom gave %GP of >95% (5%/2 mm) for all four targets. For our first 58 patients, film‐based patient‐specific quality assurance has resulted in an average %GP of 98.7% (range, 94–100%) at 2%/2 mm.

Conclusions

Core ZAP‐X features were found to be functional. On the basis of our results, point‐dose and planar measurements were in agreement with TPS calculations using multiple phantoms and setup geometries, validating the ZAP‐X TPS beam model for clinical use.
Pediatric obstructive sleep apnea—Dental professionals can play a crucial role
Authors: Fagundes Nathalia Carolina Fernandes , Flores‐Mir Carlos
Published: January 2021

The significant contribution of dental professionals to the management of selected adult obstructive sleep apnea (OSA) cases is understood. Among children, it has also been suggested that dental professionals may also help screen and manage this morbidity in selected cases. It has also been noted that our understanding of pediatric OSA lags significantly behind adult OSA. During the screening process for potential pediatric OSA cases, dental professionals may be quite helpful as specific craniofacial abnormalities have been previously associated with pediatric OSA, including Class II malocclusion, vertical facial growth and maxillary transversal deficiency. As dental professionals assess children more frequently than physicians, they can help screen sleep‐disordered breathing signs and symptoms using validated questionnaires. In more advanced cases, orthodontists may be leading contributors to the management of selected cases where a craniofacial involvement is suspected. Rapid maxillary expansion and mandibular or maxillary anterior repositioning devices have been proposed as managing alternatives. So far, there is no substantial evidence if these approaches can be adopted to treat OSA fully or if the reported OSA signs and symptoms improvements observed in a selected group of patients are stable long‐term. Nevertheless, dentists and orthodontists' integration into a transdisciplinary team should be encouraged to play a significant role. This review discusses dentists or orthodontists' potential contribution to screen and manage selective pediatric OSA patients as part of a transdisciplinary team.
Effect of Mixed Isocyanate Curing Agents on the Performance of In Situ‐Prepared HTPE Binder Applied in Propellant
Authors: Chen Keke , Yuan Shen , Wen XiaoMu , Sang Chao , Luo Yunjun
Published: January 2021

A novel hydroxyl‐terminated block copolymer (HTPE) binder was prepared through an in situ preparation method to replace the traditional HTPE binder. The preparation method is less costly and bypasses the preparation of the HTPE prepolymer intermediate, thus avoiding the complicated prepolymer synthesis process. Uniaxial tensile testing, low‐field nuclear magnetic resonance, and infrared spectroscopy were used to investigate the mechanical properties, curing networks, and hydrogen bonding (H‐bonds) of the binder. The crosslink density (Ve) decreased with an increase in the ratio of −NCO in the IPDI to the total −NCO in the IPDI and N100 (χ). The proportion of H‐bonds formed by the imino groups increased with the IPDI content and reached 86.53 % at a χ value of 90 %, indicating a positive correlation between the H‐bonds and σm. Additionally, to study the pot life of the in situ‐prepared HTPE binder, the rheological properties of the curing reactions were studied. When the χ value was in the range of 50 %–90 %, the pot life of the binder met the composite propellant requirements for military applications. The thermal decomposition behaviors of the in situ‐prepared HTPE binder and the traditional HTPE binder were investigated by the coupling analysis of thermogravimetry‐Fourier transform infrared spectroscopy (TG‐FTIR), and the novel in situ‐prepared HTPE binder exhibited good thermal stability and superior energetic performance. Compared with the traditional HTPE‐based propellant, the mechanical properties of the in situ‐prepared‐HTPE‐based propellants were greatly improved. With these data, the in situ‐prepared HTPE binder has great potential for application in rocket propellant formulations.
Investigation of Electrically Controlled Ammonium Nitrate – Epoxy Solid Propellant at High Pressures
Authors: Zamir Inna , Ben‐Reuven Moshe , Gany Alon , Grinstein Dan
Published: January 2021

The effect of electric voltage/power application on the burning rate of solid propellants composed of ammonium nitrate (AN) and epoxy at high pressures was investigated experimentally. Such an effect can yield an effective means for real‐time managing of the thrust of a solid rocket motor. A burning rate increase up to about 4 folds when increasing voltage application from 70 V to 200 V, was demonstrated. It was attributed to energy (heat) release due to an electric current passing through the conductive melt layer formed at the burning surface. The relative increase in burning rate due to electric effect was higher at the lower pressure range, diminishing for the higher‐pressure end because of the lower relative electric energy contribution. The common pressure dependence correlation of the burning rate could be applied only for limited ranges. However, because of the coupling between the pressure and specific electric power (power per unit surface area) effects, a more complex correlation which includes a variable pressure exponent, was revealed and applied successfully to fit the data over a range of specific electric power and pressure.
Effect of an additional health‐professional‐led exercise programme on clinical health outcomes after hip fracture
Authors: Beckmann Monica , Bruun‐Olsen Vigdis , Pripp Are Hugo , Bergland Astrid , Smith Toby , Heiberg Kristi E.
Published: January 2021

Purpose

To examine the effect of an additional 2‐week health professional‐led functional exercise programme compared to usual care for patients after hip fracture during a short‐term nursing home stay directly after hospital discharge.

Method

One hundred and forty participants, 65 years or older with hip fracture, admitted to a short‐term nursing home stay were randomised to an intervention group or control group. Participants in the intervention group (n = 78) received the experimental programme consisted of functional exercises, performed by health care professionals up to four times a day, 7 days a week, in addition to usual care during a 2‐week short‐term nursing home stay. Participants in the control group (n = 62) received usual care alone. Primary outcome was Short Physical Performance Battery (SPPB). Secondary outcomes were Timed Up & Go, New Mobility Score, The University of California, Los Angeles Activity Scale, Fall Efficacy Scale International, The EuroQol five dimension five‐level questionnaire, and Numeric Rating Scale for pain. Outcome measures were assessed after 2 weeks in a short‐term nursing home stay and 3 months after hip fracture surgery. The activity monitor ActivPal registered activity during the 2‐week short‐term nursing home stay.

Results

No statistically significant differences between groups was found in any outcomes after 2 weeks or 3 months (p > 0.05). There were statistically significant within‐group improvements in primary outcome SPPB and in most secondary outcomes at all time points in both groups (p > 0.05).

Conclusions

A 2‐week health professional‐led functional exercise programme in addition to usual care demonstrated no difference in clinical outcomes compared to usual care alone up to 3 months after hip fracture. The patients with hip fracture are fragile and vulnerable in this early phase, and usual physiotherapy may be sufficient to improve their physical function.

Trial registration: ClinicalTrials.gov NCT02780076.
Reduced Reverse Gate Leakage Current for p‐GaN Gate High‐Electron‐Mobility Transistors by a Surface‐Etching Method
Authors: Sun Chi , Ding Xiaoyu , Wei Xing , Tang Wenxin , Zhang Xiaodong , Zhao Desheng , Li Shuping , Yu Guohao , Song Liang , Cai Yong , Zeng Zhongming , Zhang Baoshun
Published: January 2021

Herein, the mechanism of increased gate leakage current observed in SiNx‐passivated high‐resistivity cap layer high‐electron‐mobility transistors (HRCL‐HEMTs) is investigated. The leakage is found to be correlated with the roughened morphology and deviated surface stoichiometry caused by H‐plasma treatment. An additional step of surface etching before passivation restores GaN surface and gate leakage is reduced by about two orders of magnitude, whereas the other electrical characteristics of p‐GaN HEMTs are preserved.
Initial measurement of beryllium‐9 using high‐resolution inductively coupled plasma mass spectrometry allows for more precise applications of the beryllium isotope system within the Earth Sciences
Authors: Sproson Adam D. , Aze Takahiro , Behrens Bethany , Yokoyama Yusuke
Published: January 2021

Rationale

Precise and accurate determination of the ratio of the cosmogenic nuclide 10Be to the stable isotope 9Be (10Be/9Be) is needed across multiple fields of research within the Earth Sciences. Current techniques used to measure the 9Be content of geological materials generally require a large amount of sample or solution aliquot and present a large range of analytical precisions.

Methods

A range of geological reference materials underwent whole‐rock dissolution and “strong” (0.04 M NH2OH.HCl in 25% acetic acid) and “weak” (0.02 M NH2OH.HCl in 10% acetic acid) leaching to represent a range of potential applications within the geosciences. After treatment, the 9Be and major element (Na, Ca, Mg, Fe, Mn, Al and Ti) content of sample solutions were determined by high‐resolution inductively coupled plasma mass spectrometry (HR‐ICP‐MS) using a Thermo® ELEMENT XR instrument.

Results

The 9Be concentration of whole‐rock and leaching solutions displayed a wide range of values within each geological reference material, generally following a uniform relationship implying a potential kinetic control on NH2OH leaching, as suggested by major element profiles. A precision of 0.1 to 1.4% is achieved independent of sample size or leaching strength.

Conclusions

Initial results suggest that the use of HR‐ICP‐MS improves the precision of 9Be analysis for a range of geological reference materials. A high precision is maintained despite reducing the sample size or strength of leaching solution. This has implications for the use of the Be isotope system within the Earth Sciences by reducing the propagated uncertainty of 10Be/9Be ratios or the mass of sample or 9Be aliquot used.
A prescribed‐performance‐like control for improving tracking performance of networked robots
Authors: Zhai Di‐Hua , Xia Yuanqing
Published: January 2021

To balance the performance and implementability of classical predefined performance control algorithm when its hard constraint is violated, this article investigates a switching‐based prescribed‐performance‐like control (PPLC) approach for nonlinear teleoperation systems. To achieve the objective, a switching mechanism is introduced into the classical controller design and based on this, a nonlinear proportional plus auxiliary compensation controller is designed, where a switched filter control technique is employed. By modeling the resulting closed‐loop system as a special switched delayed system and using the piecewise Lyapunov‐Krasovskii functional method, the state‐independent input‐to‐output stabilty of closed‐loop system is established, where a feasible range of the “initial” values of piecewise continuous performance function is given to achieve a tradeoff between the closed‐loop stability and overshoot. It is shown that the developed switching‐based PPLC approach obtains better performance than the classical predefined performance control algorithms. Simulations on a pair of 3‐DOF planar arms illustrate the approach.
Multienzyme‐Mimic Ultrafine Alloyed Nanoparticles in Metal Organic Frameworks for Enhanced Chemodynamic Therapy
Authors: Yang Peipei , Tao Jia , Chen Fengfeng , Chen Yuying , He Jiaqi , Shen Kui , Zhao Peng , Li Yingwei
Published: January 2021

Nanozyme‐based chemodynamic therapy (CDT) has emerged as an effective cancer treatment because of its low side effects and without the requirement of exogenous energy. The therapeutic effect of CDT highlights the pivotal importance of active sites, H2O2 supplement and the glutathione (GSH) depletion of a nanozyme. The construction of a single kind of catalyst with multiple functions for the enhanced CDT is still a big challenge. In this work, seven types of bimetallic nanoparticles are synthesized using a metal–organic framework (MOF) as a stable host instead of a Fenton or Fenton‐like ions supplier. Among them, Cu‐Pd@MIL‐101 with an alloy loading of 9.5 wt% modified by PEG (9.5% CPMP) is found to exhibit the highest peroxidase (POD) like activity combined with a superoxide dismutase (SOD) mimic activity and the function of GSH depletion. The in vivo results suggest that the stable and ultrafine nanoparticles possess favorable CDT effect for tumor and good biosafety as well as biocompatibility. This work has provided a credible strategy to construct nanozymes with an excellent activity and may pave a new way for the design of enhanced tumor CDT treatment.
Liquid‐Based Exfoliation of Black Phosphorus into Phosphorene and Its Application for Energy Storage Devices
Authors: Rabiei Baboukani Amin , Khakpour Iman , Drozd Vadym , Wang Chunlei
Published: January 2021

Black phosphorus (BP) as a rising star among 2D materials has attracted attention for a wide range of applications due to its fascinating properties. The key point for the real application of phosphorene depends on its exfoliation technique to produce high‐quality nanosheets. In recent years, tremendous efforts have been made in the preparation and energy storage application of phosphorene and phosphorene‐based hybrid electrodes. Herein, the state‐of‐the‐art liquid‐based exfoliation and characterization of phosphorene fabricated by sonication, anodic and cathodic electrochemical exfoliation, and bipolar electrochemical exfoliation in diverse solutions and conditions are discussed. In addition, the electrochemical properties and storage mechanism of phosphorene‐based electrodes for rechargeable batteries and supercapacitors are discussed. Finally, the challenges and opportunities of phosphorene nanosheets in terms of exfoliation and energy storage applications are addressed.
State of the art on composite cold‐formed steel flooring systems
Authors: Karki Dheeraj , Far Harry
Published: January 2021

This article presents a comprehensive review of the state of the art in composite cold‐formed steel flooring research over the past couple of years. The most relevant and significant literature references were reviewed to provide some insights into trends and developments in composite cold‐formed steel floors. Advantages of this type of composite flooring system are also highlighted. A broad description of mainly two types of composite floor – mainly consisting of cold‐formed steel and concrete, and cold‐formed steel and timber‐based floorboards – are outlined in this study. The experimental and numerical investigations that have been carried out worldwide are likewise discussed in the paper. The most important aspects covered are shear connection behaviour and the flexural and dynamic behaviour of the floors. There is also a brief description of fire testing.