bluuebunny/crossref_metadata_2025 huggingface dataset:
Computed Tomography–Based Stiffness Measures of Trabecular Bone Microstructure: Cadaveric Validation and In Vivo Application
Authors: Guha Indranil , Zhang Xialiou , Rajapakse Chamith S. , Letuchy Elena M. , Chang Gregory , Janz Kathleen F. , Torner James C. , Levy Steven M. , Saha Punam K.
Published: April 2022

Osteoporosis causes bone fragility and elevates fracture risk. Applications of finite element (FE) analysis (FEA) for assessment of trabecular bone (Tb) microstructural strength at whole‐body computed tomography (CT) imaging are limited due to challenges with Tb microstructural segmentation. We present a nonlinear FEA method for distal tibia CT scans evading binary segmentation of Tb microstructure, while accounting for bone microstructural distribution. First, the tibial axis in a CT scan was aligned with the FE loading axis. FE cubic mesh elements were modeled using image voxels, and CT intensity values were calibrated to ash density defining mechanical properties at individual elements. For FEA of an upright volume of interest (VOI), the bottom surface was fixed, and a constant displacement was applied at each vertex on the top surface simulating different loading conditions. The method was implemented and optimized using the ANSYS software. CT‐derived computational modulus values were repeat scan reproducible (intraclass correlation coefficient [ICC] ≥ 0.97) and highly correlated (r ≥ 0.86) with the micro‐CT (μCT)‐derived values. FEA‐derived von Mises stresses over the segmented Tb microregion were significantly higher (p < 1 × 10−11) than that over the marrow space. In vivo results showed that both shear and compressive modulus for males were higher (p < 0.01) than for females. Effect sizes for different modulus measures between males and females were moderate‐to‐high (≥0.55) and reduced to small‐to‐negligible (<0.40) when adjusted for pure lean mass. Among body size and composition attributes, pure lean mass and height showed highest (r ∈ [0.45 0.56]) and lowest (r ∈ [0.25 0.39]) linear correlation, respectively, with FE‐derived modulus measures. In summary, CT‐based nonlinear FEA provides an effective surrogate measure of Tb microstructural stiffness, and the relaxation of binary segmentation will extend the scope for FEA in human studies using in vivo imaging at relatively low‐resolution. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.
Clinical manifestations, treatment options, and comorbidities in COVID‐19 relapse patients: A systematic review
Authors: Koupaei Maryam , Mohamadi Mohamad Hosein , Yashmi Ilya , Shahabi Amir Hossein , Shabani Amir Hosein , Heidary Mohsen , Khoshnood Saeed
Published: April 2022

Introduction

Interest revolving around coronavirus disease 2019 (COVID‐19) reinfection is escalating rapidly. By definition, reinfection denotes severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), PCR redetection, and COVID‐19 recurrence within three months of the initial symptoms. The main aim of the current systematic review was to evaluate the features of COVID‐19 relapse patients.

Materials and methods

For this study, we used a string of terms developed by a skilled librarian and through a systematical search in PubMed, Web of Science, and Embase for eligible studies. Clinical surveys of any type were included from January 2019 to March 2021. Eligible studies consisted of two positive assessments separated by a negative result via RT‐PCR.

Results

Fifty‐four studies included 207 cases of COVID‐19 reinfection. Children were less likely to have COVID‐19 relapse. However, the most patients were in the age group of 20–40 years. Asthenia (66.6%), headache (66.6%), and cough (54.7%) were prevalent symptoms in the first SARS‐CoV‐2 infection. Asthenia (62.9%), myalgia (62.9%), and headache (61.1%) were most frequent in the second one. The most common treatment options used in first COVID‐19 infection were lopinavir/ritonavir (80%), oxygen support (69.2%), and oseltamivir (66.6). However, for the treatment of second infection, mostly antibiotics (100%), dexamethasone (100%), and remdesivir (80%) were used. In addition, obesity (32.5%), kidney failure (30.7%), and hypertension (30.1%) were the most common comorbidities. Unfortunately, approximately 4.5% of patients died.

Conclusion

We found the potency of COVID‐19 recurrence as an outstanding issue. This feature should be regarded in the COVID‐19 management. Furthermore, the first and second COVID‐19 are similar in clinical features. For clinically practical comparison of the symptoms severity between two epochs of infection, uniform data of both are required. We suggest that future studies undertake a homogenous approach to establish the clinical patterns of the reinfection phenomena.
Red blood cell distribution width‐to‐albumin ratio is associated with all‐cause mortality in cancer patients
Authors: Lu Chengdong , Long Jianyun , Liu Haiyuan , Xie Xupin , Xu Dong , Fang Xin , Zhu Yuandong
Published: April 2022

Background

Cancer causes a serious health burden on patients worldwide. Chronic low‐level inflammation plays a key role in tumorigenesis and prognosis. However, the role of the red blood cell distribution width (RDW)‐to‐albumin (RA) ratio in cancer mortality remains unclear.

Methods

In this retrospective cohort study, we collected clinical information from cancer patients from the Medical Information Mart for Intensive Care III (MIMIC‐III) version 1.4 database and then calculated RA by dividing RDW by albumin concentration. The primary outcome was 30 days mortality, while secondary outcomes were 90 days and 1 year mortality. Next, we adopted Cox regression models to calculate hazard ratios (HR) together with 95% confidence intervals (CI) for all‐cause mortalities associated with the RA ratio.

Results

For 30 days mortality, the HR (95% CI) for the high RA ratio (≥5.51) was 2.17 [95CI% (1.87–2.51); p = <0.0001], compared with the low RA ratio (<5.51). In Model 2, we adjusted sex and age and obtained HR (95% CI) of 2.17 [95CI% (1.87–2.52); p = <0.0001] for the high RA ratio (≥5.51) group, compared to that in the low RA ratio (<5.51). In Model 3, adjusting for age, sex, anion gap, hematocrit, white blood cell count, congestive heart failure, SOFA, liver disease, and renal failure resulted in HR (95% CI) of 1.74 [95CI% (1.48–2.04); p = <0.0001] for the high RA ratio (≥5.51) relative to the low RA ratio (<5.51). We also analyzed common diseases in cancer patients but found no significant association.

Conclusion

To the best of our knowledge, this is the first study demonstrating that increased RA ratio is independently associated with increased all‐cause mortality in cancer patients.
A script‐based method for achieving distortion‐free selected area electron diffraction
Authors: Mitchell David R. G.
Published: April 2022

Electron diffraction patterns obtained on a TEM contain elliptical distortion resulting from column defects. This distortion can be corrected by applying offsets to the objective lens stigmators to cancel distortions occurring further down the column. In this work, a DigitalMicrographTM script‐based method has been developed to identify the optimum objective stigmator settings which produce a distortion minimum in diffraction. Initially, a manual (by eye) correction is used to determine the stigmator values necessary to bring the pattern distortion below the threshold at which it is no longer visible to the naked eye (<1%). Thereafter, an automated acquisition script is used to acquire matrices of diffraction patterns while varying the stigmator values about the values which were identified as producing a distortion minimum in the preceding step. This analysis can be applied iteratively to refine the location of the distortion minimum, using progressively finer step changes in objective stigmator values. The optimum stigmator values producing the distortion minimum in diffraction are very different to those in imaging. These imaging and diffraction stigmator values can be saved to script and subsequently recalled at the click of a button, making their application very simple. Using this method, diffraction pattern elliptical distortion in a newly installed TEM was reduced from 1.6% to 0.3%, on a measurement precision of 0.3%, effectively producing distortion‐free diffraction. The relevant scripts can be freely downloaded from the internet.

Research Highlights

This paper reports a DigitalMicrograph script‐based method to identify and subsequently apply optimized objective stigmator values in diffraction mode. These effectively eliminate elliptical distortion inherent to this diffraction technique.
Comparison of the osseointegration of implants placed in areas grafted with HA/TCP and native bone
Authors: Lima Julia Raulino , Soares Priscilla Barbosa Ferreira , Pinotti Felipe Eduardo , Marcantonio Rosemary Adriana Chiérici , Marcantonio‐Junior Elcio , de Oliveira Guilherme José Pimentel Lopes
Published: April 2022

This study evaluated the osseointegration of implants in areas grafted with biphasic ceramic based on hydroxyapatite/β‐tricalcium phosphate (HA/TCP) and in native bone (NB). Twenty‐eight rats were randomly assigned into two groups of 14 animals each: HA/TCP group: implants installed in areas grafted with HA/TCP and NB group: implants installed in areas of native bone. Bone defects were made in both tibiae of the rats belonging to the HA/TCP group and then filled with this bone substitute. After 60 days, the rats were submitted to surgical procedures for implant placement in grafted areas in both tibiae in the HA/TCP group while the implants were installed directly in native bone in the NB group. The animals were euthanized 15 and 45 days, respectively, after the implant placement. Biomechanical (removal torque), microtomographic (volume of mineralized tissues around the implants), and histomorphometric (Bone‐Implant contact—%BIC and bone area between the implant threads—%BBT) analyzes were conducted to assess the osseointegration process. The HA/TCP group showed lower values of removal torque, volume of mineralized tissue around the implants, lower %BIC, and %BBT compared to the NB group in both experimental periods. Osseointegration of implants placed in grafted areas with HA/TCP was lower compared to the osseointegration observed in native bone areas.

Research Highlights

The areas grated with HA/TCP presented poor biological conditions.

The reduced biological properties for bone formation impaired the osseointegration in HA/TCP grafted areas.
Morphology of the tongue dorsal surface of turbot (Scophthalmus maximus)
Authors: Onuk Burcu , Yardımcı Banu , Selviler‐Sizer Sedef , Kabak Murat
Published: April 2022

This study aimed to analyze the morphology of the tongue, which varies among fish species and has not been studied in turbot (Scophthalmus maximus), using macro‐anatomical, light and scanning electron microscopy (SEM). As research materials, the tongues of eight adult turbot, which were used for consumption, were examined. The roughly triangular‐shaped tongue of the turbot consisted of three parts: apex, body, and root. The thickness of the tongue continued to increase from the apex to the root. Although papillae were not observed in the macroscopic examination of the tongue, microscopic examination revealed the presence of cone‐like shaped papillae on the submucosa. The tongue was composed of mucosa, submucosa, and hyaline cartilage. By SEM the presence of the taste buds (Types I and III), taste pores and papillae on the dorsal surface were demonstrated. Taste buds are the first descriptions in S. maximus. Therefore our results could add new data to the fish tongue anatomy.

Highlights

Morphological and morphometric data of the turbot (Scophthalmus maximus) tongue were obtained in this study and compared with other species. In addition, the dorsal surface of the turbot tongue was described for the first time using SEM.
Golden‐Angle Radial MRI: Basics, Advances, and Applications
Authors: Feng Li
Published: April 2022

In recent years, golden‐angle radial sampling has received substantial attention and interest in the magnetic resonance imaging (MRI) community, and it has become a popular sampling trajectory for both research and clinical use. However, although the number of relevant techniques and publications has grown rapidly, there is still a lack of a review paper that provides a comprehensive overview and summary of the basics of golden‐angle rotation, the advantages and challenges/limitations of golden‐angle radial sampling, and recommendations in using different types of golden‐angle radial trajectories for MRI applications. Such a review paper is expected to be helpful both for clinicians who are interested in learning the potential benefits of golden‐angle radial sampling and for MRI physicists who are interested in exploring this research direction. The main purpose of this review paper is thus to present an overview and summary about golden‐angle radial MRI sampling. The review consists of three sections. The first section aims to answer basic questions such as: what is a golden angle; how is the golden angle calculated; why is golden‐angle radial sampling useful, and what are its limitations. The second section aims to review more advanced trajectories of golden‐angle radial sampling, including tiny golden‐angle rotation, stack‐of‐stars golden‐angle radial sampling, and three‐dimensional (3D) kooshball golden‐angle radial sampling. Their respective advantages and limitations and potential solutions to address these limitations are also discussed. Finally, the third section reviews MRI applications that can benefit from golden‐angle radial sampling and provides recommendations to readers who are interested in implementing golden‐angle radial trajectories in their MRI studies.

Evidence Level

5

Technical Efficacy

Stage 1
Fragmentation pathways of deprotonated ortho‐hydroxybenzyl alcohol
Authors: Kumar Meenu , Zheng Zhaoyu , Nishshanka Upul , Xia Hanxue , Weisbecker Carl , Attygalle Athula B.
Published: April 2022

The ortho, meta, and para isomers of hydroxybenzyl alcohol can be unequivocally distinguished by the collision‐induced dissociation mass spectra of their anions. The presence of a prominent peak at m/z 121 for an elimination of a dihydrogen molecule renders the ortho‐isomer spectrum markedly different from those of its meta and para congeners. Investigations carried out with deuterium‐labeled isotopologues of the ortho isomer verified that the labile hydrogen atom on the hydroxyl group and one of the benzylic hydrogen atoms are specifically removed in the formation of the m/z 121 ion. The ortho‐isomer spectrum also showed a prominent peak at m/z 93. Experimental data indicated that the m/z 93 product ion originates either from a two‐step H2and CO elimination mechanism or from a direct loss of a HCHO molecule from the precursor anion. The intensity ratio of the m/z 93 and 94 peaks in the spectrum recorded from the m/z 124 ion generated from a sample of o‐hydroxybenzyl alcohol dissolved in D2O supported the notion that the direct HCHO loss is the more dominant pathway for the generation of the phenolate ion under low activation conditions. In contrast, the two‐step mechanism becomes the more dominant pathway under high collisional activation conditions. The spectrum also showed a weak peak at m/z 105 for a water loss. Based on computational data, the m/z 105 ion generated in this way appears to be a composite generated from a common ion‐neutral complex intermediate in which a hydroxyl anion is positioned equidistantly between one of the benzylic hydrogens and a nearby hydrogen atom of the benzene ring. Upon activation, the complex dissociates to form either a phenide or a quinone methide anion. The reaction forming a carbon dioxide adduct under ion‐mobility conditions was used to support the proposed water‐loss mechanism.
Robust design of fractional order IMC controller for fractional order processes with time delay
Authors: Gnaneshwar Kurnam , Trivedi Rishika , Padhy Prabin Kumar
Published: April 2022

This article presents a novel approach to the robust design of fractional order IMC controller for the fractional‐order (FO) plus time delay processes. The proposed methodology provides the flexibility to adjust the controller performance based on the application requirement using a single parameter. Also, it does not require any external filter. Thus, it ensures a better response over existing methods. A mathematical analysis is provided to select the tuning parameter to obtain the optimal solution. The effectiveness of the proposed methodology is measured for different FO processes with time delay using time‐domain specifications, performance indices and frequency domain parameters. Load disturbance analysis under various disturbances and robust analysis under uncertainty in process gain in the presence of the disturbances is carried out to study the sensitivity and robustness of the controller. The performance parameters are estimated in both analyses and compared with the different approaches available in the literature.
The characteristics of mesoscale convective systems generated over the Yunnan–Guizhou Plateau during the warm seasons
Authors: Guo Yuanjing , Du Yu , Lu Riyu , Feng Xinxian , Li Jun , Zhang Yuanchun , Mai Zi
Published: April 2022

The characteristics of mesoscale convective systems (MCSs) over the Yunnan–Guizhou Plateau (YGP) during the warm seasons (April–August) are investigated using an automatic tracking algorithm based on long‐term (2000–2018) hourly geostationary satellites data of temperature of black body. A total of 1,845 MCSs generated over the YGP are identified and further classified into the eastward moving type (EMT; ~13.1%) and noneastward moving/dissipating type (NDT; ~86.9%). The two types of MCSs exhibit varying characteristics. The EMTs are mainly active in the eastern flank of the YGP with a longer mean lifespan (~16.5 hr), while the NDTs occur anywhere over the YGP with a preference for the central YGP with a shorter mean lifespan (~7.6 hr). The MCSs are observed most frequently during June–July, while the ratio of EMTs reaches the highest in April due to the strongest steering flows. The abundant moisture supply plays a vital role in the generation and development of MCSs in June, whereas the dynamic forcing and high CAPE are favourable to MCSs in July. In terms of the diurnal cycle, the NDTs are generally initiated in the afternoon, reach mature in the late afternoon, and dissipate at night. By contrast, the mature stage of EMTs shows double diurnal peaks in the late afternoon and early morning. The MCSs are usually generated in an instable environment accompanied by strong vertical wind shear and intense low‐level water vapour flux over the YGP, and the MCSs tend to vacate the YGP with strong mid‐level westerlies and instable environment in the downstream regions. Compared to MCSs in Tibetan Plateau, the ratio of the EMTs is higher with longer lifespans though fewer MCSs are generated over the YGP.
Hyper‐Raman spectral signatures of structured and de‐structured hydrogen‐bonded water
Authors: Korepanov Vitaly , Yu Chun‐Chieh , Hamaguchi Hiro‐o
Published: April 2022

Hyper‐Raman (HR) spectra of liquid water have been measured in the temperature range from 15 to 45°C. A total of 76 spectra obtained at an interval of about 0.5°C are analyzed by singular value decomposition (SVD) and multivariate curve resolution with alternate least squares (MCR‐ALS) analyses. Obtained temperature‐dependent HR spectra are univocally decomposed into two components, corresponding to de‐structured hydrogen‐bonded water (DH water) and structured hydrogen‐bonded water (SH water). The results are in complete agreement with those of Raman spectroscopy, supporting the understanding that SH water and DH water coexist in thermal equilibrium in ambient liquid water.
Supplementation of sulfur and folic acid improves performance of broiler chicken fed suboptimal concentrations of dietary methionine
Authors: Rao Savaram Venkata Rama , Raju Mantena Venkata Lakshmi Narasimha , Srilatha Thota , Nagalakshmi Devanaboyina , Rajkumar Ullengala
Published: April 2022

BACKGROUND

Supplementation of sulfur (S) and folic acid (FA) are known to spare the dietary requirement of methionine (Met) in chicken. An experiment was conducted to determine the effects of feeding graded concentrations of FA (0, 2, 4, 6, 8 mg kg−1) and two concentrations of S (0 and 2 g kg−1) in 5 × 2 factorial design. Diet without FA and S was considered as negative control (NC). Another diet with the recommended concentration of Met was considered as the positive control (PC). Each diet was offered ad libitum from day 1 to 42 to 10 pens of 20 male chicks each.

RESULTS

Broilers fed the NC diet had lower body weight gain (BWG), high feed conversion ratio, lower ready‐to‐cook yield, higher lipid peroxidation and reduced concentrations of protein and albumin in serum. BWG improved with FA at day 21 and showed a trend of improvement at day 42. Similarly, BWG improved with S supplementation at day 42. The FA and S interaction indicated a significant reduction in lipid peroxidation with S supplementation at the majority of FA levels. Serum protein fractions increased with increased dietary FA content and increased further with S supplementation.

CONCLUSION

Based on the results, it is concluded that the combination of FA (4 mg kg−1) and S (2 g kg−1) improved BWG. Similarly, the feed efficiency with 6 mg FA alone or with S was similar to the PC group. The improvement was probably due to the increase in protein accretion and reduction in lipid peroxidation with FA and S supplementation. © 2022 Society of Chemical Industry.
Effect of harvest time span on physicochemical properties, antioxidant, antimicrobial, and anti‐inflammatory activities of Meliponinae honey
Authors: Wu Ming‐Cheng , Wu Cheng‐Yin , Klaithin Kanokwan , Tiong Kuok Kiang , Peng Chi‐Chung
Published: April 2022

BACKGROUND

The maturity of honey has a great impact on its quality and contents. Additionally, stingless bee honey contains high moisture, which allows microorganisms to survive and ferment, contributing to honey's variable flavor and physicochemical properties. Therefore, there is a need for better quality control of the honey process, especially the harvest time of honey.

RESULTS

We gathered honey from the nest of stingless bees Heterotrigona itama and Tetrigona binghami over different time periods, i.e. 15, 30, and 45 days. The results show harvest time considerably affects the physicochemical properties, antioxidant activity, and antimicrobial activity of honey. Good antioxidant activity and antimicrobial activity can be found in honey produced from a longer harvest time. Compared with 15‐day harvest time, at 30‐ or 45‐day harvest time water, trehalulose, and protein content and total acidity increased, and the content of reducing sugars, fructose and glucose, and pH values, decreased in both types of honey. Moreover, compared with 15‐day harvest time, the sum of six organic acids in the 45‐day honey of H. itama fluctuated between 2.78 to 4.12 g 100 g−1 and in the 45‐day honey of T. binghami increased from 1.66 to 3.61 g 100 g−1, respectively.

CONCLUSION

Honey harvest time had a significant effect on the physicochemical properties, antioxidant activity, and antimicrobial activity of stingless bee honey (H. itama or T. binghami). This study provides a reference for beekeepers to adjust harvest time to obtain honey with suitable physicochemical parameters. © 2022 Society of Chemical Industry.
Speckle‐Tracking Analysis in Fetuses With Tetralogy of Fallot: Evaluation of Right and Left Ventricular Contractility and Left Ventricular Function
Authors: DeVore Greggory R. , Afshar Yalda , Harake Danielle , Satou Gary , Sklansky Mark
Published: April 2022

Objectives

This study examines fetuses with tetralogy of Fallot (TOF) and evaluates the right (RV) and left (LV) ventricular contractility and LV function using speckle‐tracking analysis of the endocardium.

Methods

The study group consisted of 44 fetuses with TOF, of which 34% had pulmonary valve atresia (N = 15) and 59% (N = 26) had pulmonary valve stenosis. The RV and LV global fractional area change, longitudinal contractility (longitudinal strain, free wall strain, septal strain, free wall and septal annular fractional shortening, and free wall and septal wall annular plane systolic excursion), and transverse contractility (24‐segment fractional shortening) as well as LV functional assessment (stroke volume, cardiac output, and ejection fraction) were measured using speckle‐tracking analysis. The z‐scores of the measurements were compared to 200 controls.

Results

Compared to controls, measurements of LV contractility in fetuses with TOF demonstrated significantly abnormal values for global contractility, longitudinal contractility, and transverse contractility of the mid and apical segments. LV function was abnormal for stroke volume (SV), cardiac output (CO), and ejection fraction (EF). In comparison, RV contractility demonstrated no significant difference between TOF and control z‐score values for RV global contractility. Only two RV measurements were found to be abnormal: longitudinal contractility and transverse contractility of the apical segments.

Conclusion

Using multiple measurement tools to evaluate global, longitudinal, and transverse contractility, this study identified significant differences between fetuses with TOF and healthy controls, with greater contractility abnormalities seen in the LV than in the RV.
Restoration of ecologically valuable grassland on sites degraded by invasive Solidago: lessons from a 6‐year experiment
Authors: Szymura Magdalena , Świerszcz Sebastian , Szymura Tomasz H.
Published: April 2022

Most semi‐natural grasslands are threatened by invasive alien plants, which have also overgrown abandoned fields. We conducted a 6‐year experiment testing different methods of eliminating invasive Solidago species and adding seed to restore valuable species‐rich grassland. Three removal treatments (herbicide spraying, rototilling, turf stripping) and two seed addition methods (direct sowing of a fast‐growing grass species mixture, spreading of fresh hay collected from a semi‐natural meadow) were examined alongside control treatments (no removal, no seed addition). The experimental plots were mowed twice a year, and the vegetation composition, biomass production, hay chemical composition, and fodder quality were assessed. Mowing twice a year significantly reduced Solidago cover. Although significant differences were observed in the invaders' cover between the removal treatments and between the seed addition methods early in the study, the differences lessened over time, especially for the removal treatments. By the end of the 6‐year study period, the Solidago cover was reduced to 25% of the initial complete coverage. Spreading fresh hay greatly reduced Solidago biomass and yielded the highest characteristic species cover. Herbicide treatment was no more efficient than the more environmentally friendly methods over the study period. The results suggest that fresh hay is good method of seed addition for restoring old fields overgrown by invasive Solidago. With mowing of the restored area twice a year for several years, Solidago removal by turf striping (scalping) followed by the spreading of fresh hay is recommended for grassland restoration given its environmental impact, cost, and hay quality.
SPASER as Nanoprobe for Biological Applications: Current State and Opportunities
Authors: Wang Jian‐Hua , Wang Shao‐Peng , Melentiev Pavel N. , Balykin Victor I. , Xu Jing‐Juan , Chen Hong‐Yuan , Kang Bin
Published: April 2022

Since the concept of surface plasmon amplification by stimulated emission of radiation (SPASER) was proposed in 2003, great progresses have been made on two kinds of plasmonic nanolasers, namely SPASER device and SPASER nanoparticle. In comparison, SPASER nanoparticle, with ultra‐narrow emission line, small size, and good biocompatibility, is a kind of promising luminescent nanoprobe and has a bright application prospect in biomedical imaging and sensing. Hence, it is gradually becoming an attractive research hotspot in the world. However, as the research on SPASER nanoparticle is still in its infancy, there are still lots of problems to be solved before it is widely applied. In this paper, the latest research advances of SPASER nanoparticles and their biological applications are reviewed. Besides existing problems, challenges and opportunities of SPASER nanoparticles as next generation luminescent nanoprobes are discussed as well.
Donor–Acceptor Stenhouse Adduct‐Polydimethylsiloxane‐Conjugates for Enhanced Photoswitching in Bulk Polymers
Authors: Clerc Michèle , Tekin Cem , Ulrich Sebastian , Freire Rafael V. M. , Salentinig Stefan , Bruns Nico , Boesel Luciano F.
Published: April 2022

Donor–acceptor Stenhouse adducts (DASAs) are a rapidly emerging class of visible light‐activated photochromes and DASA‐functionalized polymers hold great promise as biocompatible photoresponsive materials. However, the photoswitching performance of DASAs in solid polymer matrices is often low, particularly in materials below their glass transition temperature. To overcome this limitation, DASAs are conjugated to polydimethylsiloxanes which have a glass transition temperature far below room temperature and which can create a mobile molecular environment around the DASAs for achieving more solution‐like photoswitching kinetics in bulk polymers. The dispersion of DASAs conjugated to such flexible oligomers into solid polymer matrices allows for more effective and tunable DASA photoswitching in stiff polymers, such as poly(methyl methacrylate), without requiring modifications of the matrix. The photoswitching of conjugates with varying polymer molecular weight, linker type, and architecture is characterized via time‐dependent UV–vis spectroscopy in organic solvents and blended into polymethacrylate films. In addition, DASA‐functionalized polydimethylsiloxane networks, accessible via the same synthetic route, provide an alternative solution for achieving fast and efficient DASA photoswitching in the bulk owing to their intrinsic softness and flexibility. These findings may contribute to the development of DASA‐functionalized materials with better tunable, more effective, and more reversible modulation of their optical properties.
Characteristic analysis of Omicron‐included SARS‐CoV‐2 variants of concern
Authors: Yang Hao , Liu Penghui , Zhang Yong , Du Tingfu , Zhou Yanan , Lu Shuaiyao , Peng Xiaozhong
Published: April 2022

In view of the rapid development of the COVID‐19 pandemic and SARS‐CoV‐2 mutation, we characterized the emerging SARS‐CoV‐2 variants of concern (VOCs) by both bioinformatics methods and experiments. The representative genomic sequences of SARS‐CoV‐2 VOCs were first downloaded from NCBI, including the prototypic strain, Alpha (B.1.1.7) strain, Beta (B.1.351) strain, Delta (B.1.617.2), and Omicron (B1.1.529) strain. Bioinformatics analysis revealed that the D614G mutation led to formation of a protruding spike (S) in the tertiary structure of spike protein, which could be responsible for the enhanced binding to angiotensin‐converting enzyme 2 (ACE2) receptor. The epitope analysis further showed that the S protein antigenicity of the Omicron variant changed dramatically, which was possibly associated with its enhanced ability of immune escape. To verify the bioinformatics results, we performed experiments of pseudovirus infection and protein affinity assay. Notably, we found that the spike protein of Omicron variant showed the weakest infectivity and binding ability among all tested strains. Finally, we also proved this through virus infection experiments, and found that the cytotoxicity of Omicron seems to be not strong enough. The results in this study provide guidelines for prevention and control of COVID‐19.
Antigenicity comparison of SARS‐CoV‐2 Omicron sublineages with other variants contained multiple mutations in RBD
Authors: Li Qianqian , Zhang Mengyi , Liang Ziteng , Zhang Li , Wu Xi , Yang Chaoying , An Yimeng , Tong Jincheng , Liu Shuo , Li Tao , Cui Qianqian , Nie Jianhui , Wu Jiajing , Huang Weijin , Wang Youchun
Published: April 2022

The severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) variants, particularly those with multiple mutations in receptor‐binding domain (RBD), pose a critical challenge to the efficacy of coronavirus disease 2019 (COVID‐19) vaccines and therapeutic neutralizing monoclonal antibodies (mAbs). Omicron sublineages BA.1, BA.2, BA.3, as well as the recent emergence of C.1.2, B.1.630, B.1.640.1, and B.1.640.2, have multiple mutations in RBD and may lead to severe neutralizing antibody evasion. It is urgent to evaluate the antigenic change of the above seven variants against mAbs and sera from guinea pigs immunized with variants of concern (VOCs) (Alpha, Beta, Gamma, Delta, Omicron) and variants of interest (VOIs) (Lambda, Mu) immunogens. Only seven out of the 24 mAbs showed no reduction in neutralizing activity against BA.1, BA.2, and BA.3. However, among these seven mAbs, the neutralization activity of XGv337 and XGv338 against C.1.2, B.1.630, B.1.640.1, and B.1.640.2 were decreased. Therefore, only five neutralizing mAbs showed no significant change against these seven variants. Using VOCs and VOIs as immunogens, we found that the antigenicity of variants could be divided into three clusters, and each cluster showed similar antigenicity to different immunogens. Among them, D614G, B.1.640.1, and B.1.630 formed a cluster, C.1.2 and B.1.640.2 formed a cluster, and BA.1, BA.2, and BA.3 formed a cluster.
Tunable dual‐band filter based on monolayer black phosphorus
Authors: Oliveira Cristiano , Dmitriev Victor , Melo Geraldo , Castro Wagner
Published: April 2022

We propose analytical and numerical modeling of a tunable electromagnetic dual‐band filter based on a periodic structure of black phosphorus (BP) discs deposited on silicon dioxide for operating in terahertz and infrared regions. Due to BP anisotropy, single operation dipole mode bands for polarization of incident wave in the armchair or zigzag directions exist. These bands correspond to different resonant frequencies. However, for another polarization, in particular, for a polarization, a double operation band appears. The dynamic control of the proposed structure can be performed by varying the electronic doping of the BP, thus changing the operating frequency of the filter. The analytical model based on the temporal coupled‐mode theory is in good agreement with the numerical simulations by COMSOL Multiphysics.
Temporal information‐guided dynamic dual‐tracer PET signal separation network
Authors: Tong Junyi , Wang Chunxia , Liu Huafeng
Published: April 2022

Purpose

The difficulty of dynamic dual‐tracer positron emission tomography (PET) technology is to separate the complete single‐tracer information from mixed dual‐tracer. Traditional methods cannot separate single‐injection single‐scan dynamic dual‐tracer PET images. In this paper, we propose a deep learning framework based on gated recurrent unit (GRU) network and evaluate its performance with simulation experiments and realistic monkey data.

Methods

The proposed single‐scan dynamic dual‐tracer PET image separation network consists of three parts, including encoder, separation, and decoder module. Encoder part is to map the mixed time activity curves (TACs) from the low‐dimensional space to the high‐dimensional space to get mixed weight vector matrix. Separation part is to capture the temporal information of mixed weight vector matrix using bi‐directional GRU (bi‐GRU) layer to obtain the single‐tracer masks, and the decoding part remaps the high‐dimensional single‐tracer weight vector matrix to the low‐dimensional space to obtain two separated single tracers.

Results

In the simulation experiments under different tracers, phantoms, noise levels, arterial input function (AIF), and k‐parameter with Gaussian random, compared to the stacked auto encoder network and traditional background subtraction method, GRU‐based network has better performance with low bias and mean squared error. In the realistic study, the image results of GRU network have higher mean structural similarity and peak signal to noise ratio.

Conclusions

This study demonstrates the feasibility of temporal information‐guided neural network in single‐injection single‐scan dynamic dual‐tracer PET images separation. The GRU‐based network uses TAC temporal information without AIFs to make the separation results more robust and accurate, which significantly outperforms state‐of‐the‐art method qualitatively and quantitatively.
Deep learning‐based 3D MRI contrast‐enhanced synthesis from a 2D noncontrast T2Flair sequence
Authors: Wang Yulin , Wu Wenyuan , Yang Yuxin , Hu Haifeng , Yu Shangqian , Dong Xiangjiang , Chen Feng , Liu Qian
Published: April 2022

Purpose

Gadolinium‐based contrast agents (GBCAs) have been successfully applied in magnetic resonance (MR) imaging to facilitate better lesion visualization. However, gadolinium deposition in the human brain raised widespread concerns recently. On the other hand, although high‐resolution three‐dimensional (3D) MR images are more desired for most existing medical image processing algorithms, their long scan duration and high acquiring costs make 2D MR images still much more common clinically. Therefore, developing alternative solutions for 3D contrast‐enhanced MR image synthesis to replace GBCAs injection becomes an urgent requirement.

Methods

This study proposed a deep learning framework that produces 3D isotropic full‐contrast T2Flair images from 2D anisotropic noncontrast T2Flair image stacks. The super‐resolution (SR) and contrast‐enhanced (CE) synthesis tasks are completed in sequence by using an identical generative adversarial network (GAN) with the same techniques. To solve the problem that intramodality datasets from different scanners have specific combinations of orientations, contrasts, and resolutions, we conducted a region‐based data augmentation technique on the fly during training to simulate various imaging protocols in the clinic. We further improved our network by introducing atrous spatial pyramid pooling, enhanced residual blocks, and deep supervision for better quantitative and qualitative results.

Results

Our proposed method achieved superior CE‐synthesized performance in quantitative metrics and perceptual evaluation. In detail, the PSNR, structural‐similarity‐index, and AUC are 32.25 dB, 0.932, and 0.991 in the whole brain and 24.93 dB, 0.851, and 0.929 in tumor regions. The radiologists’ evaluations confirmed that our proposed method has high confidence in the diagnosis. Analysis of the generalization ability showed that benefiting from the proposed data augmentation technique, our network can be applied to “unseen” datasets with slight drops in quantitative and qualitative results.

Conclusion

Our work demonstrates the clinical potential of synthesizing diagnostic 3D isotropic CE brain MR images from a single 2D anisotropic noncontrast sequence.
Development of a dosimetry system for therapeutic X‐rays using a flexible amorphous silicon thin‐film solar cell with a scintillator screen
Authors: Jeong Seonghoon , Cheon Wonjoong , Shin Dongho , Lim Young Kyung , Jeong Jonghwi , Kim Haksoo , Yoon Myonggeun , Lee Se Byeong
Published: April 2022

Purpose

To evaluate the dosimetric characteristics and applications of a dosimetry system composed of a flexible amorphous silicon thin‐film solar cell and scintillator screen (STFSC‐SS) for therapeutic X‐rays.

Methods

The real‐time dosimetry system was composed of a flexible a‐Si thin‐film solar cell (0.2‐mm thick), a scintillator screen to increase its efficiency, and an electrometer to measure the generated charge. The dosimetric characteristics of the developed system were evaluated including its energy dependence, dose linearity, and angular dependence. Calibration factors for the signal measured by the system and absorbed dose‐to‐water were obtained by setting reference conditions. The application and correction accuracy of the developed system were evaluated by comparing the absorbed dose‐to‐water measured using a patient treatment beam with that measured using the ion chamber.

Results

The responses of STFSC‐SS to energy, field size, depth, and source‐to‐surface distance (SSD) were more dependent on measurement conditions than were the responses of the ion chamber, although the former dependence was due to the scintillator screen, not the solar cell. The signals of STFSC‐SS were also dependent on dose rate, while the responses of solar cell alone and scintillator screen were not dependent on dose rate. The scintillator screen reduced the output of solar cell at 6 and 15 MV by 0.60 and 0.55%, respectively. The different absorbed dose‐to‐water measured using STFSC‐SS for patient treatment beam differed by 0.4% compared to those measured using the ionization chamber. The uncertainties of the developed system for 6 and 15 MV photon beams were 1.8 and 1.7%, respectively, confirming the accuracy and applicability of this system.

Conclusions

The thin‐film solar cell‐based detector developed in this study can accurately measure absorbed dose‐to‐water. The increased signal resulting from the use of the scintillator screen is advantageous for measuring low doses and stable signal output. In addition, this system is flexible, making it applicable to curved surfaces, such as a patient's body, and is cost‐effective.
A branch‐and‐cut algorithm for the pickup‐and‐delivery traveling salesman problem with handling costs
Authors: Radha Krishnan Devaraj , Liu Tieming
Published: April 2022

In the Pickup‐and‐Delivery Traveling Salesman Problem with Handling Costs (PDTSPH), a single vehicle has to satisfy multiple customer requests, each defined by a pickup location and a delivery location. Cargo handling is performed at the rear end of the vehicle, in a Last‐In‐First‐Out (LIFO) order for PDTSPH. However, additional handling operations are permitted with a penalty if other loads that block the access to the delivery have to be unloaded and reloaded. The objective of PDTSPH is to minimize the total transportation and handling cost. In this paper, we present a new Mixed Integer Programming (MIP) model and a branch‐and‐cut algorithm to solve PDTSPH. We also present new integral separation procedures to effectively handle the exponential number of constraints in our MIP model. A family of inequalities are introduced to enhance the scalability of our implementation. The performance of our approach is compared with a compact formulation from the literature (Veenstra et al. [21]) in instances ranging from 9 to 21 customer requests. Computational results show our algorithm outperforming the compact formulation in 69% of instances with an average runtime improvement of 57%.
Thermal‐induced dielectric response in mechanically durable polyvinylidene fluoride–kapok encapsulated polyethylene glycol composite films
Authors: Gong Yutie , Li Zhenzhen , Li Hairong , Wu Wenqi , Pei Xianglin , Tu Junyang , Zhou Weijie , Jiang Ming , Gong Wei
Published: April 2022

Dielectric materials with thermally responsive property are being pursued in fields such as next‐generation sensors, smart switches, and novel actuators. These applications require that the dielectric materials have mechanical durability and stable serviceability besides thermally responsive dielectric behavior. Herein, we report a novel thermally responsive, mechanically durable, and low‐cost dielectric composite simply fabricated by vacuum impregnating polyethylene glycol (PEG) into kapok fiber and compounding them with polyvinylidene fluoride. A remarkable dielectric susceptibility, controlled dielectric transition temperature, and obvious thermal hysteresis of the composite films induced by the solid–liquid phase transition of PEG are demonstrated. The effect of molecular weights of PEG on the dielectric response behaviors is evaluated. Such thermally responsive dielectric materials with satisfactory mechanical durability will offer a chance toward constructing thermally responsive systems for reliable and stable operation.
Synthesis and characterization of block copolymers of styrene‐maleic acid with acrylamide and N,N‐dimethylacrylamide
Authors: Khaojanta Thidarat , Kalaithong Wichaya , Somsunan Runglawan , Punyamoonwongsa Patchara , Mahomed Anisa , Topham Paul D. , Tighe Brian J. , Molloy Robert
Published: April 2022

Styrene‐maleic acid (SMA) block copolymers with either acrylamide (AM) or N,N‐dimethylacrylamide (DMA) have been synthesized via a 3‐step process comprising: (1) photopolymerization of styrene and maleic anhydride in solution to yield an alternating styrene maleic anhydride (SMAnh) copolymer, (2) copolymerization of SMAnh with either AM or DMA to yield SMAnh‐b‐AM and SMAnh‐b‐DMA block copolymers and (3) hydrolysis of the anhydride groups to yield water‐soluble SMA‐b‐AM and SMA‐b‐DMA block copolymers as the final products. With a view to their intended application in membrane protein solubilization, molecular weights are controlled to below 10,000 by the synthesis conditions employed in step (1), including using carbon tetrabromide (CBr4) as a chain transfer agent. The CBr4 also plays an important role in step (2). By terminating the SMAnh chain radicals from step (1) with C‐Br bonds that are photolytically active, SMAnh chain radicals can be regenerated to act as macroinitiators for the polymerization of AM or DMA in step (2). Finally, following step (3) and due to the pH‐dependency of the SMA chain conformation in solution, a pH of 7–8 is found to be optimal for enabling the final products to be precipitated in a solid form that is completely soluble in water.
Impact of proton pump inhibitors on sustained virologic response in veterans treated with sofosbuvir/velpatasvir for chronic hepatitis C virus: A retrospective cohort study
Authors: Rumph Danielle M. , Straley Craig M. , Kolberg Jenny L. , Jacob David A.
Published: April 2022

Study Objective

The objective of this study was to determine the clinical relationship between proton pump inhibitor (PPI) use and sustained virologic response (SVR) in patients treated with sofosbuvir/velpatasvir (SOF/VEL) for chronic hepatitis C virus (HCV) infection.

Design

This was a multicenter retrospective cohort study.

Setting

Data was collected on patients from 128 Veterans Affairs Medical Centers throughout the United States.

Patients

This study included veterans aged 18‐89 years with viremic HCV who received a full course of SOF/VEL treatment from June 2016 – July 2017.

Intervention

Sustained viral response was compared in patients taking SOF/VEL with or without concurrent PPI prescriptions.

Measurements and Main Results

Analysis of the primary outcome was completed utilizing logistic regression. The relationship between SVR and PPI use was adjusted for African‐American race, presence of cirrhosis, prior treatment, BMI greater than 30 kg/m2, and HCV genotype. The final analysis included 4,008 veterans, 830 with concomitant PPI use and 3,178 without PPI use. After adjustment for other variables in the logistic model, there was no statistically significant association between PPI use and lower SVR (odds ratio 0.67; 95%CI: 0.42, 1.06; p = 0.087).

Conclusion

Concomitant PPI treatment adjusted for other variables did not significantly impact success or failure of SOF/VEL treatment of chronic HCV. Despite the lack of significant association identified in this study, in efforts to provide the best care possible, it remains prudent to proceed with caution in patients desiring to use PPI therapy while receiving SOF/VEL, and ensure prescribing instructions are closely followed in regard to concomitant PPI use, especially in patients with other risk factors for decreased SVR.