bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of Screw Extrusion of Thermoplastics for AM
Authors: Mittal Yash Gopal , Prajapati Shivam , Kamble Pushkar , Trushnikov Dmitriy , Bernard Alain , P. Karunakaran K. 
Published: April 2021

Abstract
3D printing is an Additive Manufacturing (AM) process that enables physical realization of a CAD (Computer-Aided Design) model. 3D printing can be classified into several variants; Material Extrusion Additive Manufacturing (MEAM) is the most versatile and widely used. MEAM is a continuous extrusion and selective deposition process commonly used for thermoplastics. Screw Extrusion Additive Manufacturing (SEAM), a sub-domain of MEAM, uses an extruder screw to push the polymer-melt out of the nozzle. Computational Fluid Dynamics (CFD) analysis of a single screw extrusion of thermoplastics is presented in this paper. The effect of various control parameters like screw rotation, wall heat flux/temperature profile, screw geometry, etc., has been studied on the required output parameters like productivity, torque capacity, power requirement, metering efficiency, etc. It is found that the incrementally-variable-pitch screw geometry provides the best metering characteristics. However, every screw design is a compromise between melt temperature, productivity, and power requirements.
Meteorology and Climatology of Historical Weekly Wind and Solar Power Resource Droughts over western North America in ERA5
Authors: Brown Patrick T , Farnham David J. , Caldeira Ken 
Published: April 2021

Abstract
Wind and solar electricity generation is projected to expand substantially over the next several decades due both to rapid cost declines as well as regulation designed to achieve climate targets. With increasing reliance on wind and solar generation, future energy systems may be vulnerable to previously underappreciated synoptic-scale variations characterized by low wind and/or surface solar radiation. Here we use western North America as a case study region to investigate the historical meteorology of weekly-scale “droughts” in potential wind power, potential solar power and their compound occurrence. We also investigate the covariability between wind and solar droughts with potential stresses on energy demand due to temperature deviations away human comfort levels. We find that wind power drought weeks tend to occur in late summer and are characterized by a mid-level atmospheric ridge centered over British Columbia and high sea level pressure on the lee side of the Rockies. Solar power drought weeks tend to occur near winter solstice when the seasonal minimum in incoming solar radiation co-occurs with the tendency for mid-level troughs and low pressure systems over the U.S. southwest. Compound wind and solar power drought weeks consist of the aforementioned synoptic pattern associated with wind droughts occurring near winter solstice when the solar resource is at its seasonal minimum. We find that wind drought weeks are associated with high solar power (and vice versa) both seasonally and in terms of synoptic meteorology, which supports the notion that wind and solar power generation can play complementary roles in a diversified energy portfolio at synoptic spatiotemporal scales over Western North America.
CD80 and CD86: expression and prognostic value in newly diagnosed glioblastoma
Authors: Ahmed Mohammed , Hernández-Verdin Isaias , Verreault Maite , Bielle Franck , Lerond Julie , Alentorn Agusti , Sanson Marc , Idbaih Ahmed 
Published: April 2021

Abstract
Purpose

Strategies to modulate the tumor microenvironment (TME), including the vascular and immune components, have opened new therapeutic avenues with dramatic yet heterogeneous intertumor efficacy in multiple cancers, including brain malignancies. Therefore, investigating molecular actors of TME may help understand the interactions between tumor cells and TME. Immune checkpoint proteins such as a Cluster of Differentiation 80 (CD80) and CD86 are expressed on the surface of tumor cells and infiltrative tumor lymphocytes. However, their expression and prognostic value in glioblastoma (GBM) is still unclear.

Methods

In this study, we have investigated, in a retrospective local discovery cohort and a validation TCGA dataset, expression of CD80 and CD86 at mRNA level and their prognostic significance in response to standard of care. CD80 and CD86 at the protein level were also investigated in the discovery cohort.

Results

Both CD80 and CD86 are expressed heterogeneously in GBM at mRNA and protein levels. In a univariate analysis, the mRNA expression of CD80 and CD86 was not significantly correlated with OS in both ONT and TCGA datasets. On the other hand, CD80 and CD86 mRNA high expression was significantly associated with shorter PFS (p<0.05). These findings were validated using the TCGA cohort; higher CD80 and CD86 expressions were correlated with shorter PFS (p<0.05). In multivariate analysis, CD86 mRNA expression was an independent prognostic factor for PFS in the TCGA dataset only (p<0.05).

Conclusion

Additional studies are warranted to validate our findings and to explore the expression of CD80 and CD86 in GBM patients treated with immunotherapy and, more specifically, with CTLA-4 inhibitors.
Effects of Terminalia chebula Retz. on the Secretion of Somatostatin in the Small Intestine in Mice
Authors: He Min , Zhao Si-Qi , Guo Xi-Yan 
Published: April 2021

Abstract
Objective: This study investigated the effects of Terminalia chebula Retz. (TC) and its two processed products Rubia cordifolia L. per Terminalia chebula Retz. (RTC) and Euphorbia fischeriana Steud per Terminalia chebula Retz. (ETC) on the secretory activity of somatostatin cells in the small intestine in mice. Methods: A total of 168 twenty-day-old SPF Kunming mice were randomly divided into seven groups, i.e., the control (saline, 0.1 g/kg), high TC, RTC, ETC and low TC, RTC, and ETC groups, and administered drugs for 28 days. The cellular localization and expression of SS in the small intestine were assessed by immunohistochemistry after drug delivery for 7, 14, 21 or 28 days. Results: The somatostatin（SS）protein was widely distributed in the small intestines of mice. Immunoreactivity gradually decreased in the duodenum to the ileum. SS immunoreactivity was significantly lower in the high TC, RTC, ETC and low RTC, and ETC groups compared with the control group after drug delivery for 28 days. The efficacy of RTC was better than that of ETC and obviously better than that of TC. The efficacies of high dosages of TC and its processed products were better than those of low dosages of the drugs. SS cells of various shapes, including cone-, spindle-, and ellipse-shaped SS cells, were observed. A large number of SS cells were found in the intestinal gland epithelium and intestinal lamina propria in the control group, and these cells were widely distributed in epithelial cells in the intestinal mucosa and intestinal gland epithelium in the experimental groups. Conclusions: This study indicates that TC and its processed products play an important role in inhibiting the secretion of SS to different degrees. The effect of the RTC at a dosage of 4.0 g·kg–1 BW is the best.
Review of Bounding Box Algorithm Based on 3D Point Cloud
Authors: Siwei He , Baolong Liu 
Published: April 2021

Abstract
Collision detection is mainly to judge whether there is intersection between virtual models, which means there is collision. Bounding box is one of the important methods of collision detection. It uses regular geometry with simple structure to replace the complex model to be detected. A simple point cloud model usually contains hundreds or thousands of polygons when meshed. When collision tests are performed directly on the geometry of two model objects, the calculation process is relatively complex. In order to reduce the computational cost, the bounding box test of the model was performed before the geometry intersection test. Only when the bounding box has a collision, can further accurate intersection detection be carried out. This paper mainly introduces the content and significance of the bounding box, and compares four kinds of common bounding boxes and their advantages and disadvantages as well as the application scenarios of the bounding box. Firstly, the content and significance of the bounding box are expounded. Secondly, it is analyzed according to different bounding boxes. Finally, the different bounding box algorithms are summarized, and the advantages and disadvantages of different bounding boxes and application scenarios are pointed out.
Release of chromite nanoparticles and their alteration in the presence of Mn-oxides
Authors: McClenaghan Neal W. , Schindler Michael 
Published: April 2021

Abstract
The discovery of chromite nanoparticles in silicates of ultramafic rocks may change our approach on the environmental risk assessment of mine waste associated with chromitite mining. This experimental study shows for the first time that the alteration of Cr-rich silicates results in the release of chromite nanoparticles and that their interaction with oxidizing Mn-oxide nanoparticles causes the dissolution of chromite and Mn-oxide nanoparticles and the precipitation of Fe3+- and Cr3+-hydroxides. Transmission electron microscopy (TEM) in combination with ultra-microtomy, centrifugation, chromatography, ICP-MS, and UV-VIS is used to characterize release and alteration of chromite nanoparticles and the concentrations and speciation of Cr aqueous species. Alteration of clinochlore grains containing chromite nanoparticles results in the release of the nanoparticles and their attachment to Si-bearing Alhydroxide colloids. Chromite nanoparticles with the end-member composition FeCr2O4 are synthesized, and their interaction with Mn-oxide nanoparticles (hausmannite, Mn3O4), Fe2+-silicates (chamosite, [(Fe3.9Mg0.62Al0.48)Al(Si3Al)O10(OH)8] and organic matter is studied over a period of six to nine months in suspensions of pH = 5. The interaction of chromite and hausmannite nanoparticles is facilitated by the aggregation of the nanoparticles and dissolution-precipitation processes. Processes on the surfaces of the hausmannite nanoparticles include the reductive dissolution of the substrate (reduction of Mn3+ to Mn2+ by Fe2+ species) and its replacement by amorphous or nanocrystalline Cr3+-bearing Fe3+-hydroxides. Processes on the surfaces of the chromite nanoparticles involve the attachment of hausmannite nanoparticles, the oxidative dissolution of the substrate (oxidation of Fe2+ and perhaps Cr3+ by Mn3+ species), its replacement by an amorphous or nanocrystalline Mn-bearing Cr3+-hydroxide matrix and the formation of the Cr3+-hydroxides bracewellite and grimaldite within the latter matrix. Analyses of the suspensions indicate only minor amounts of Cr6+ in the suspensions (&lt;5 µg kg−1) suggesting that formation or occurrence of Cr6+ species can be limited in complex geochemical and mineralogical systems even in the presence of hausmannite nanoparticles.
Water in the crystal structure of CaSiO3 perovskite
Authors: Shim Sang-Heon , Chizmeshya Andrew , Leinenweber Kurt 
Published: April 2021

Abstract
While the water storage capacities of the upper 700 km depths of the mantle have been constrained by high-pressure experiments and diamond inclusion studies, the storage capacity of the lower mantle remains controversial. A recent high-pressure experimental study on CaSiO3 perovskite, which is the third most abundant mineral in the lower mantle, reported possible storage of H2O up to a few weight percent. However, the substitution mechanism for H in this phase remains unknown. We have conducted a series of density functional theory calculations under static-lattice conditions and high pressures to elucidate hydration mechanisms at the atomic scale. All of the possible dodecahedral (Ca2+ → 2H+) and octahedral (Si4+ → 4H+) substitution configurations for a tetragonal perovskite lattice have very small energy differences, suggesting the coexistence of multiples of H configurations in CaSiO3 perovskite at mantle pressures and temperatures. The dodecahedral substitutions decrease the bulk modulus, resulting in a smaller unit-cell volume of hydrous CaSiO3 perovskite under pressure, consistent with the experimental observations. Although the octahedral substitutions also decrease the bulk modulus, they increase the unit-cell volume at 1 bar. The H atoms substituted in the dodecahedral sites develop much less hydrogen bonding with O atoms, leading to a large distortion in the neighboring SiO6 octahedra. Such distortion may be responsible for the non-cubic peak splittings observed in experiments on hydrous CaSiO3 perovskite. Our calculated infrared spectra suggest that the observed broad OH modes in CaSiO3 perovskite can result from the existence of multiples of H configurations in the phase. Combined with the recent experimental results, our study suggests that CaSiO3 can be an important mineral phase to consider for the H2O storage in the lower mantle.
Novel Design Proposal for the Seismic Retrofit of Existing Buildings with Hybrid Steel Exoskeletons and Base Sliding Devices
Authors: Sancin Ljuba , Bedon Chiara , Amadio Claudio 
Published: April 2021

Background:
Existing Reinforced Concrete (RC) structures and brittle buildings are often exposed to seismic events that may have significant resistance and displacement demand compared to their actual capacity. Accordingly, an optimal retrofit intervention can ensure enhanced and safe structural performances for them. Among the techniques that have been addressed for the retrofit of existing RC frames, steel exoskeletons can notoriously improve the seismic performance of existing buildings due to their input stiffness, ductility and resistance. In this paper, the attention is focused on the interaction of steel exoskeletons with RC frames and the consequent details to achieve a more effective design of the retrofit intervention.

Objective:
Based on parametric calculations, a new hybrid design concept that takes advantage of traditional steel exoskeletons with additional base sliding devices (at the foundation level of the RC frame to retrofit) is addressed in this paper.

Methods:
As shown through SDOF and 2D-MDOF calculations, the definition of the optimal operational conditions (and thus mechanical configurations) for the so-assembled hybrid solution can maximize the potential of the retrofit intervention, with marked benefits in terms of ductility, resistance, and overall efficiency, ensuring very low damage in the existing building.

Results:
Given that the used base sliders are bidirectional, it is expected that the proposed solution could be efficiently extended to 3D structures, once the exoskeleton systems are optimally designed along the two principal directions of the hybrid structure to retrofit.

Conclusion:
The potential of the hybrid approach is shown based on parametric analyses. Furthermore, general design recommendations are proposed for the hybrid solution.
Self-Reported Symptoms in a Cohort of Rheumatoid Arthritis and Systemic Lupus Erythematosus during the COVID-19 Quarantine Period
Authors: Salido Evelyn O. , Tee Cherica A. , Reyes Patrick W. C. , Reyes Heizel B. M. , Zamora Geraldine T. , Tee Michael L. 
Published: April 2021

Background:
During the first three months of the COVID-19 pandemic in the Philippines, there was a supply shortage of hydroxychloroquine and methotrexate. Limited access to medication and the life changes resulting from the COVID-19 pandemic may predispose patients with rheumatoid arthritis (RA) or systemic lupus erythematosus (SLE) to disease flares.

Objective:
This study aimed to investigate self-reported symptoms of disease flares among patients with rheumatoid arthritis or systemic lupus erythematosus during the COVID-19 pandemic.

Methods:
A total of 512 completed online surveys from patients with SLE or RA were collected. The data included sociodemographic characteristics, self-reported physical symptoms, health service utilization, and availability of hydroxychloroquine and methotrexate.

Results:
Seventy-nine percent of respondents had lupus, while 21% had RA. One-third of the cohort had contact with their attending physician during the two-month quarantine period prior to the survey. Eighty-two percent were prescribed hydroxychloroquine and 23.4% were prescribed methotrexate; but 68.6% and 65%, respectively, had “irregular” intake of these medicines due to unavailability. The current health status was reported as good by 66.2%; 24% had no symptoms during the two-week period prior to the survey. The most common symptoms experienced were joint pain (51%), muscle pain (35%), headache (26.8%), and skin rash (19.1%). Five percent had a combination of these four most common symptoms. Irregular supply of hydroxychloroquine among patients with SLE (n=323) was associated with more frequent occurrence of muscle pain (40.6% vs 27.9%, p=0.03) or rash (27.4% vs 11.7%, p<0.001). Irregular supply of methotrexate among RA patients prescribed hydroxychloroquine and methotrexate (n=36) was associated with more frequent occurrence of joint pains with or without swelling (73.9% vs 38.5%, p=0.04). Irregular supply of hydroxychloroquine was associated with less frequent occurrence of dizziness (0 vs 66.7%, p<0.001) among RA patients (n=18).

Conclusion:
In our cohort of RA and SLE, the majority reported at least one symptom that may indicate disease flare. There was a significant association between the irregular supply of hydroxychloroquine or methotrexate with the presence of muscle pain, rash, or joint pains during the 14-day period prior to the survey.
Long-Term Visual, Refractive and Topographic Outcomes of KeraRings Combined with Accelerated Transepithelial Crosslinking for Management of Different Grades of Progressive Keratoconus: A Retrospective Cohort Study
Authors: Iqbal Mohammed , Mounir Amr , Abd-Elaziz Khaled , Said Omar M. 
Published: April 2021

Purpose:
To evaluate long-term visual, refractive, and topographic outcomes of KeraRings intrastromal implantation combined with accelerated transepithelial cross-linking for management of different stages of progressive keratoconus.

Materials and Methods:
This retrospective cohort study included 70 eyes of 70 patients with Amsler-Krumeich grades 1 to 4 keratoconus. They were divided into two groups: group-A included 37 eyes with grades 1-2 keratoconus, and group-B included 33 eyes with grades 3-4 keratoconus. Both groups underwent combined Keraring implantation with TCXL treatment. The main outcome measures included the preoperative and postoperative visual acuity, refraction, keratometry readings, and pachymetry.

Results:
At postoperative month 60, group-B exhibited significantly higher values of all mean uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), sphere/cylinder/spherical equivalent/defocus equivalent (DEQ), and K1/K2/Kaverages/Kmax parameters compared to that of group A. However, group-A exhibited better stability of postoperative improvements. Keratoconus progression (KCP) was greater in group-B (45.5%) than group-A (10.8%). Two eyes revealed segments' migration while one eye showed tunnel vascularization and opacification with segments' migration.

Conclusion:
The diagnostic criteria of preoperative-KCP are not adequate for the diagnosis of postoperative-KCP following ICRS implantation. UDVA and K average posterior seemed to be more sensitive parameters than K max in documenting early postoperative-KCP. We suggest that deterioration of UDVA≥0.10 log MAR and/or K average posterior ≥0.25 D are highly suspicious of post-ring implantation keratoconus progression (PR-KCP). The occurrence of two of the following parameters: Kmax≥0.50 D, Kaverageanterior≥0.50 D, K average posterior ≥0.25 D, or pachymetry≥1.5% thinning, is diagnostic of PR-KCP. The occurrence of two or more of the following parameters: Kmax≥0.50 D, Kaverageanterior≥0.50 D, Kaverageposterior ≥0.25 D, pachymetry≥ 1.5% thinning or UDVA≥0.10 logMAR, is diagnostic of PR-KCP. We also suggest that Kmax≥0.75 D alone is diagnostic of PR-KCP.
The Influence of the COVID-19 Epidemic on Prevention and Vaccination Behaviors Among Chinese Children and Adolescents: Cross-sectional Online Survey Study
Authors: Hou Zhiyuan , Song Suhang , Du Fanxing , Shi Lu , Zhang Donglan , Lin Leesa , Yu Hongjie 
Published: April 2021

BackgroundThe COVID-19 epidemic and the related containment strategies may affect parental and pediatric health behaviors.ObjectiveThe goal of this study was to assess the change in children’s and adolescents’ prevention and vaccination behaviors amid China’s COVID-19 epidemic.MethodsWe conducted a cross-sectional online survey in mid-March 2020 using proportional quota sampling in Wuhan (the epidemic epicenter) and Shanghai (a nonepicenter). Data were collected from 1655 parents with children aged 3 to 17 years. Children’s and adolescents’ prevention behaviors and regular vaccination behaviors before and during the epidemic were assessed. Descriptive analyses were used to investigate respondents’ characteristics, public health prevention behaviors, unproven protection behaviors, and vaccination behaviors before and during the COVID-19 epidemic. Univariate analyses were performed to compare differences in outcome measures between cities and family characteristics, using chi-square tests or Fisher exact tests (if expected frequency was <5) and analyses of variance. Multivariate logistic regressions were used to identify the factors and disparities associated with prevention and vaccination behaviors.ResultsParent-reported prevention behaviors increased among children and adolescents during the COVID-19 epidemic compared with those before the epidemic. During the epidemic, 82.2% (638/776) of children or adolescents always wore masks when going out compared with 31.5% (521/1655) before the epidemic; in addition, 25.0% (414/1655) and 79.8% (1321/1655) had increased their frequency and duration of handwashing, respectively, although only 46.9% (776/1655) went out during the epidemic. Meanwhile, 56.1% (928/1655) of the families took unproven remedies against COVID-19. Parent-reported vaccination behaviors showed mixed results, with 74.8% (468/626) delaying scheduled vaccinations and 80.9% (1339/1655) planning to have their children get the influenza vaccination after the epidemic. Regarding socioeconomic status, children and adolescents from larger families and whose parents had lower education levels were less likely to improve prevention behaviors but more likely to take unproven remedies. Girls were less likely than boys to always wear a mask when going out and wash their hands.ConclusionsPrevention behaviors and attitudes toward influenza vaccination have improved during the COVID-19 epidemic. Public health prevention measures should be continuously promoted, particularly among girls, parents with lower education levels, and larger families. Meanwhile, misinformation about COVID-19 remains a serious challenge and needs to be addressed by public health stakeholders.