bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of a plasma synthesized polypyrrole coverage on polylactic acid/hydroxyapatite scaffolds for bone tissue engineering
Authors: Flores‐Sánchez María G. , Islas‐Arteaga Nancy C. , Raya‐Rivera Atlántida M. , Esquiliano‐Rendon Diego R. , Morales‐Corona Juan , Uribe‐Juarez Omar E. , Vivar‐Velázquez Flor I. , Ortiz‐Vázquez Greta P. , Olayo Roberto 
Published: April 2021

AbstractComposite biomaterials are solids that contain two or more different materials, combining the properties of their components to restore or improve the function of tissues. In this study, we report the generation of electrospun matrices with osteoconductive properties and porosity using the combination of a biodegradable polyester, polylactic acid (PLA), and hydroxyapatite (HA). Additionally, we report the effects of modifying these matrices through plasma polymerization of pyrrole on the growth and osteogenic differentiation of rabbit bone marrow stem cells. Cells were isolated, seeded and cultured on biomaterials for periods between 7 and 28 days. The matrices we obtained were formed by nano and microfibers containing up to 35.7 wt% HA, presenting a variety of apparent pore sizes to allow for the passage of nutrients to bone cells. Scanning electron microscopy showed that the fibers were coated with polypyrrole doped with iodine, and MTT assay demonstrated this increased cell proliferation and significantly improved cell viability due to the adhesive properties of the polymer. Our results show that PLA/HA/Pyrrole/Iodine matrices are favorable for bone tissue engineering.
Efficacy and safety of infrahepatic inferior vena cava clamping under controlled central venous pressure for reducing blood loss during hepatectomy: A randomized controlled trial
Authors: Junrungsee Sunhawit , Suwannikom Karnpichamonch , Tiyaprasertkul Worakamol , Lapisatepun Worakitti , Chotirosniramit Anon , Sandhu Trichak , Chandacham Kamtone , Jirapongcharoenlap Tidarat , Lapisatepun Warangkana , Ko‐iam Wasana 
Published: April 2021

AbstractBackgroundThe purpose of this study was to evaluate the effectiveness and safety of inferior vena cava (IVC) clamping for reducing blood loss during hepatectomy.MethodsIn total, 120 elective hepatectomy patients who underwent surgery from May 2016 to October 2017 were enrolled and randomized into the IVC clamping group or nonclamping group. Both groups were managed by anesthesiological techniques for CVP reduction. Blood loss and clinical parameters were analyzed for 30 days after surgery.ResultsFifty‐nine patients were assigned to the IVC clamping group and 61 to the non‐IVC clamping group. There was a significant difference in the total blood loss between both groups, with less blood loss observed in the IVC clamping group [500 vs 600 mL, P = .006]. The transection blood loss in the IVC clamping group was also significantly lower than that in the non‐IVC clamping group [300 vs 500 mL, P < .001]. However, CVP was not associated with blood loss volume. Postoperative outcomes were not significant in either group.ConclusionsIVC clamping is beneficial for reducing blood loss during hepatectomy and is safe when combined with anesthesiological techniques. If feasible, this technique should be used regardless of the CVP value.
Low‐cost surrogate modeling of antennas using two‐level Gaussian process regression method
Authors: Zhang Zhen , Jiang Fan , Jiao Yaxi , Cheng Qingsha S. 
Published: April 2021

AbstractIn order to improve the accuracy of the surrogate model for antennas, a novel two‐level Gaussian process regression (GPR) modeling method is proposed in this paper. A heuristic hypercube sampling method is proposed using the K‐means clustering method to generate the training dataset with high uniformity. Based on the training dataset, the first‐level GPR model is established between the design parameters and the full‐wave electromagnetic (EM) simulation responses. The second‐level GPR model is established using the design parameters and the residuals between the first‐level GPR model and the EM simulation model. The sum of the two surrogate models is the two‐level GPR model. The performance of the proposed modeling method is verified by two antenna examples including an ultra‐wideband antenna and a circularly polarized dielectric antenna. Numerical results show that the proposed two‐level GPR method achieves higher accuracy of antenna models than the conventional methods (GPR method and neural networks) with no additional cost. The overall time saving of the proposed method compared to the conventional methods is more than 50% for the majority of our tests.
Targeting SARS‐CoV‐2 Spike Protein/ACE2 Protein‐Protein Interactions: a Computational Study
Authors: Pirolli Davide , Righino Benedetta , De Rosa Maria Cristina 
Published: April 2021

AbstractThe spike glycoprotein (S) of the SARS‐CoV‐2 virus surface plays a key role in receptor binding and virus entry. The S protein uses the angiotensin converting enzyme (ACE2) for entry into the host cell and binding to ACE2 occurs at the receptor binding domain (RBD) of the S protein. Therefore, the protein‐protein interactions (PPIs) between the SARS‐CoV‐2 RBD and human ACE2, could be attractive therapeutic targets for drug discovery approaches designed to inhibit the entry of SARS‐CoV‐2 into the host cells. Herein, with the support of machine learning approaches, we report structure‐based virtual screening as an effective strategy to discover PPIs inhibitors from ZINC database. The proposed computational protocol led to the identification of a promising scaffold which was selected for subsequent binding mode analysis and that can represent a useful starting point for the development of new treatments of the SARS‐CoV‐2 infection.
Automatic clinical target volume delineation for cervical cancer in CT images using deep learning
Authors: Shi Jialin , Ding Xiaofeng , Liu Xien , Li Yan , Liang Wei , Wu Ji 
Published: April 2021

PurposeAccurately delineating clinical target volumes (CTV) is essential for completing radiotherapy plans but is time‐consuming, labor‐intensive, and prone to inter‐observer variation. Automating CTV delineation has the benefits of both speeding up contouring process and improving the quality of contours. Recently, auto‐segmentation approaches based on deep learning have achieved some improvements. However, unlike organ segmentation, the CTV contains potential tumor spread tissues or subclinical disease tissues, resulting in poorly defined margin interface and irregular shape. It is not reasonable to directly apply the deep learning segmentation algorithms to CTV tasks without considering the unique characteristics of shape and margin. In this work, we propose a novel automatic CTV delineation algorithm based on deep learning addressing the unique shape and margin challenges.MethodsOur deep learning method, called RA‐CTVNet, segments the CTV from cervical cancer CT images. RA‐CTVNet denotes our automatic CTV delineation algorithm based on deep learning with Area‐aware reweight strategy and Recursive refinement strategy. (1) In order to process the whole‐volume CT images and delineate all CTVs in one shot, our method is built upon the popular 3D Unet architecture. We further extend it with robust residual learning and squeeze‐and‐excitation blocks for better feature representation. (2) We propose area‐aware reweight strategy which assigns different weights for different slices. The core is adjusting model’s attention to each slice. (3) In terms of the trade‐off between providing performance improvements and meeting the limitations of GPU memory, we exploit a new recursive refinement strategy to address margin challenge.ResultsThis retrospective study included 462 patients diagnosed with cervical cancer who received radiotherapy from June 2017 to May 2019. Extensive experiments were conducted to evaluate performance of RA‐CTVNet. First, compared to different network architectures, RA‐CTVNet achieved improvements in Dice similarity coefficient (DSC). Second, we conducted ablation study. The results showed that compared to the backbone, area‐aware reweight strategy increased DSC by 3.3% on average and recursive refinement strategy further increased DSC by 1.6% on average. Then, we compared our method with three human experts. Our RA‐CTVNet performed better than two experts while comparably to the third expert. Finally, a multicenter evaluation was conducted to verify the accuracy and generalizability.ConclusionsOur findings show that deep learning is able to offer an efficient framework for automatic CTV delineation. The tailored RA‐CTVNet can improve the quality of CTV contours, which has great potential for reducing the burden of experts and increasing the accuracy of delineation. In the future, if with more training data, further improvements are possible, bringing this approach closer to real clinical practice.
Predictor‐based H∞ leader‐following consensus of stochastic multi‐agent systems with random input delay
Authors: Li Ke , Mu Xiaowu 
Published: April 2021

AbstractIn this paper, we investigate H∞ leader‐following consensus of multi‐agent systems with state multiplicative noise governed by stochastic differential equations and random time‐varying input delays which satisfy a certain probability. A new predictor‐based controller is designed based on the reduction approach to guarantee H∞ leader‐following consensus is achieved in mean square sense. By designing a Lyapunov function and using stochastic techniques, sufficient conditions are obtained in a form of linear matrix inequalities. Finally, a simulation is given to demonstrate the effectiveness of the obtained theoretical results.
Benzoxazole phenoxide ligand supported group IV catalysts and their application for the ring‐opening polymerization of rac‐lactide and ε‐caprolactone
Authors: Pappuru Sreenath , Ramkumar Venkatachalam , Chakraborty Debashis 
Published: April 2021

Monomeric titanium [C48H62N2O6Ti] (1) and zirconium [C48H62N2O6Zr] (2) complexes were synthesized by combining the monoanionic salicylbenzoxazole pro‐ligand 2‐(5‐X‐benzoxazol‐2‐yl)‐6‐R1‐4‐R2‐phenol, LH (R1, R2, X = tBu, tBu, H, respectively) with Ti(OiPr)4 or Zr(OiPr)4∙(iPrOH) in a 2:1 stoichiometric ratio. Controlled hydrolysis of the monomeric Ti complex with deionized water yielded a new unusual hexanuclear titanium complex [C126H144N6O21Ti6] (3). In addition, the cage formed in this complex 3 was surrounded by all‐oxygen and penta‐coordinated Ti(IV) atoms, which leads to an hexanuclear drum‐shaped Ti complex 3 with a trigonal‐bipyramidal geometry at the metal center. The catalytic activity of these complexes toward ring‐opening polymerization (ROP) of ε‐caprolactone (ε‐CL) and rac‐lactide (rac‐LA) was studied. All these complexes showed moderate to good catalytic activity without using any co‐catalyst additives. Single‐site zirconium alkoxide 2 showed the best catalytic activity and was able to convert 400 units of ε‐CL or rac‐LA into the polymer product in high yield (≥90%) within 1 hour under solvent‐free conditions. The obtained polymers showed good control in molecular weight (Mn = 46.2–6.3 kg/mol) and molecular weight distributions (MWD's = 1.37–1.15). The polymerization of rac‐LA by 2 yielded iso‐enriched polylactide (Pm = 0.60).
Preparation and properties of bacterial cellulose/graphene oxide composite films using dyeing method
Authors: Kiangkitiwan Nopparut , Srikulkit Kawee 
Published: April 2021

AbstractIn this study, bacterial cellulose (BC) hydrogels were cultured from a kombucha SCOBY starter. The scanning electron microscopy (SEM) results indicated that the dried BC exhibited an interpenetrating fibrous mat. The BC films harvested for 5, 10, and 15 days were 15–19, 14.4–24, and 30–31 μm thick, respectively. Then, BC/graphene oxide (GO) composite films were prepared via the exhaust dyeing method. GO sheets penetrated the BC matrix, resulting in the formation of a BC/GO composite, as revealed by the SEM analysis results. The mechanical properties of the composite films were investigated. Compared with virgin BC, the tensile strength of the composite films was higher, while the %E at break was lower, resulting in a significant increase in the Young's modulus. The X‐ray diffraction results indicated that an increase in the dyeing time (0.5–2 h) gradually induced cellulose crystalline conformation, which in turn affected the swelling ability, mechanical properties, and electrical properties of the BC/GO composite films. After the reduction of GO to reduced GO (rGO), flexible conductive BC/rGO films were obtained, as confirmed by their resistivity values. Thus, flexible conductive composite films with excellent mechanical properties were successfully fabricated.
Investigation of support type effect on plastic hinges in RC beam under impact load
Authors: Yilmaz M. Cem , Mercimek Ömer , Ghoroubi Rahim , Anil Özgür , Gültop Tekin 
Published: April 2021

AbstractThis study investigates the effect of support types on plastic hinges in reinforced concrete (RC) beam under the influence of impact loading. In previous studies, the assumption of the linear distribution of inertia force under impact loading was examined and verified according to experimental, analytical, and numerical results. Furthermore, it was emphasized that the most important parameters affecting the behavior of RC beams under impact loading were plastic hinges. A three‐stage study was planned to investigate this subject. The first stage was an experimental study. In this part, four RC beams with simple and fixed supports were tested under the low‐velocity impact load with two different impact energy levels by using a free‐weight test setup with advanced measurement techniques. The time histories of the accelerations, the displacements, and the impact loads acting on RC beams were recorded, and the cracks from impact loading were observed. The dynamic responses obtained from experiments have been interpreted in detail. The most important issue about plastic hinges was that the hinges do not reach the supports and remain on the beam. This is valid for both hinge support and fixed support. In the second stage of the study, an explicit numerical analysis model, which was verified with experimental results, was developed. The clear agreement between the experimental and numerical results was demonstrated. It has been concluded that proposed finite element procedures can be used for evaluation of the dynamic responses and failure modes of RC beams under low‐velocity impact loading. The last part was an analytical study. In this part, the proposed analytical procedure in the previous studies considering the plastic joint formed in a simple support beam under impact loading was confirmed, and a new coefficient for fixed support was proposed. A good agreement has been achieved between analytical and experimental work.
Spatial Resolution between Two Abnormalities in a Cable by Frequency Domain Reflectometry
Authors: Ohki Yoshimichi , Hirai Naoshi 
Published: April 2021

The spatial resolution of a cable fault location method by frequency domain reflectometry was examined experimentally by giving two abnormalities intentionally along a 31.5‐m coaxial cable. As a result, two clear signal peaks appear, which can locate the presence of two hot spots perfectly if they are separated by more than 30 cm at a position about 15 m from the cable end with a measuring device. In addition, a clear signal peak with a small shoulder is recognized if the two hot spots are 1 cm away. Although the abnormalities were given in this research by heating the cable using tape heaters, the spatial resolution should be theoretically similar for any type of fault in a cable as long as it changes the characteristic impedance of the cable. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.
What’s Happening to Shared Picture Book Reading in an Era of Phonics First?
Authors: Campbell Stacey 
Published: April 2021

AbstractLearning about being a reader is more than teaching phonics. A pilot study of shared picture book reading in early childhood education as a means to support young children in developing a broader understanding of literacy, in addition to phonics and phonological awareness, is discussed. The Early Language and Literacy Classroom Observation (ELLCO) (Pre‐K) tool was administered in six early childhood contexts, revealing a range of strengths and weaknesses in classrooms observed. There was little evidence of picture book reading playing an integral part of the early childhood literacy programs. Shared reading activities were absent in some contexts. In others, books were selected on the basis of length or a phonics focus. In an era of phonics first, this article is a timely reminder that shared reading of quality children’s literature can support development of a range of reading strategies including phonics while developing a joy for reading.
“What’s the Main Idea?”: Using Text Structure to Build Comprehension
Authors: Hudson Alida K. , Owens Julie , Moore Karol A. , Lambright Kacee , Wijekumar Kausalai (Kay) 
Published: April 2021

AbstractThis teaching tip aims to build awareness of using a text’s structure as a framework for building students’ reading comprehension. The authors detail the Framework for Accelerating the Strategic Comprehension of Text (FASCT) to support elementary students reading comprehension abilities by explicitly teaching students to use the structure of a text to support the development of a main idea statement after every text read. FASCT then teaches students to expand this main idea statement into a summary by adding key supporting details. Furthermore, this teaching tip outlines how teachers can implement FASCT instruction using any genre of text. Although comprehension instruction, such as FASCT, is only one part of the overall literacy block, it may be essential for building a solid foundation from which students’ complex comprehension skills can grow.
SU(5) GUTs with A4 modular symmetry
Authors: Chen Peng , Ding Gui-Jun , King Stephen F. 
Published: April 2021

Abstract
We combine SU(5) Grand Unified Theories (GUTs) with A4 modular symmetry and present a comprehensive analysis of the resulting quark and lepton mass matrices for all the simplest cases. Classifying the models according to the representation assignments of the matter fields under A4, we find that there are seven types of SU(5) models with A4 modular symmetry. We present 53 benchmark models with the fewest free parameters. The parameter space of each model is scanned to optimize the agreement between predictions and experimental data, and predictions for the masses and mixing parameters of quarks and leptons are given at the best fitting points. The best fit predictions for the leptonic CP violating Dirac phase, the lightest neutrino mass and the neutrinoless double beta decay parameter when displayed graphically are observed to cover a wide range of possible values, but are clustered around particular regions, allowing future neutrino experiments to discriminate between the different types of models.
The Bactrian effect: multiple resonances and light Dirac dark matter
Authors: Rizzo Thomas G. 
Published: April 2021

Abstract
The possibility of light dark matter (DM) annihilating through a dark photon (DP) which kinetically mixes (KM) with the Standard Model (SM) hypercharge field is a very attractive scenario. For DM in the interesting mass range below ∼ 1 GeV, it is well known that bounds from the CMB provide a very strong model building constraint forcing the DM annihilation cross section to be roughly 3 orders of magnitude below that needed to reproduce the observed relic density. Under most circumstances this removes the possibility of an s-wave annihilation process for DM in this mass range as would be the case, e.g., if the DM were a Dirac fermion. In an extra-dimensional setup explored previously, it was found that the s-channel exchange of multiple gauge bosons could simultaneously encompass a suppressed annihilation cross section during the CMB era while also producing a sufficiently large annihilation rate during freeze-out to recover the DM relic density. In this paper, we analyze more globally the necessary requirements for this mechanism to work successfully and then realize them within the context of a simple model with two ‘dark’ gauge bosons having masses of a similar magnitude and whose contributions to the annihilation amplitude destructively interfere. We show that if the DM mass threshold lies appropriately in the saddle region of this destructive interference between the two resonance humps it then becomes possible to satisfy these requirements simultaneously provided several ancillary conditions are met. The multiple constraints on the parameter space of this setup are then explored in detail to identify the phenomenologically successful regions.
Crossing bridges with strong Szegő limit theorem
Authors: Belitsky A. V. , Korchemsky G. P. 
Published: April 2021

Abstract
We develop a new technique for computing a class of four-point correlation functions of heavy half-BPS operators in planar $$ \mathcal{N} $$
N
= 4 SYM theory which admit factorization into a product of two octagon form factors with an arbitrary bridge length. We show that the octagon can be expressed as the Fredholm determinant of the integrable Bessel operator and demonstrate that this representation is very efficient in finding the octagons both at weak and strong coupling. At weak coupling, in the limit when the four half-BPS operators become null separated in a sequential manner, the octagon obeys the Toda lattice equations and can be found in a closed form. At strong coupling, we exploit the strong Szegő limit theorem to derive the leading asymptotic behavior of the octagon and, then, apply the method of differential equations to determine the remaining subleading terms of the strong coupling expansion to any order in the inverse coupling. To achieve this goal, we generalize results available in the literature for the asymptotic behavior of the determinant of the Bessel operator. As a byproduct of our analysis, we formulate a Szegő-Akhiezer-Kac formula for the determinant of the Bessel operator with a Fisher-Hartwig singularity and develop a systematic approach to account for subleading power suppressed contributions.
SYK wormhole formation in real time
Authors: Maldacena Juan , Milekhin Alexey 
Published: April 2021

AbstractWe study the real time formation of the ground state of two coupled SYK models. This is a highly entangled state which is close to the thermofield double state and can be viewed as a wormhole. We start from a high temperature state, we let it cool by coupling to a cold bath. We numerically solve for the largeNdynamics. Our main result is that the system forms a wormhole by going through a region with negative specific heat, taking time that is independent ofN. The dynamics is smooth everywhere and it seems to follow the equilibrium thermodynamic configurations of the microcanonical ensemble. Also we comment on the relation between this coupled SYK model and Jackiw-Teitelboim gravity theory with bulk fields.