bluuebunny/crossref_metadata_2025_split huggingface dataset:
Setting time and standard consistency of Portland cement binders blended with rice husk ash, calcium carbide and metakaolin admixtures
Authors: Babako M , Apeh JA 
Published: June 2020

Abstract
The use of pozzolanic materials to reduce carbon dioxide (CO2) emissions and enhanced properties of mortar and concrete has received increased interests in the last decades. In this study, admixtures such as metakaolin (MK), rice husk ash (RHA) and calcium carbide waste (CCW) partially replaced Portland cement (PC) at 5, 10, 20 % in multiple combinations of aforementioned admixtures as binders and the effect of setting times (initial and final) and standard consistency on the binders were evaluated. The Department of Environment (DOE) approach for mix proportions was employed. The mixes are in six groups consisting of control PC, each admixture replaced PC at 5, 10 and 20 % replacement level in binary mixes, then two of the admixtures replaced PC at same replacement level in ternary and the three admixtures replaced PC in quaternary mixes respectively. Results indicated that RHA significantly influenced the standard consistency of the binders incorporating the three admixtures as compared with CCW and MK. The requirement of water in the binder increased with increase in percentage replacement level of RHA within the binder due to its porous nature. At 5 % replacement level, it was 9 % above control value, 21 % and 39 % at 10 and 20 % replacement level subsequently. Similarly, setting times at the aforementioned replacement levels are 27 % and 6 % above the control value for initial and final setting time. For 20 % replacement level, it was 24 % and 38 % above the control value for the initial and final setting time respectively. This is due to reduction in PC content leading to less content of Tricalcium silicate aluminate (C3A) and amount of carbon content within the pozzolanic materials which retard the rate of reactions. By and large, the admixtures retard the setting times of quaternary binder, and increased its water of consistency which can be overcome by activation. However, they are useful in the construction of concrete structural elements or structures that requires longer time for placement. Furthermore, it will be worthwhile to investigate same properties at the nanoscale since these have been established at the micro level.
Optimization studies on biosynthesis of iron nanoparticles using Rhizopus stolonifer
Authors: Adeleye TM , Kareem SO , Kekere-Ekun AA 
Published: June 2020

Abstract
Isolates from pure culture of Rhizopus stolonifer were aseptically grown in potato dextrose broth to early exponential phase and centrifuged. The biological synthesis of Iron nanoparticles from the fungus was carried out using simple techniques. Filtrates obtained by simple methods were reacted with 1 M Ferric chloride solution. Characterization of the synthesized iron nanoparticles was monitored using Ultraviolet-visible spectrophotometer and Fourier transform infrared spectroscopy (FTIR). An increase in synthesis of the iron nanoparticles by over 200% occurred when culture of selected isolate was agitated. At 325 nm, peaks of absorbance (3.5) were read at pH 4.5 and 6, while maximum production of the iron nanoparticles was reached at 35 °C. Peaks of transmittance of biosynthesized iron nanoparticles from selected isolate as shown by the FTIR spectrum were located at 750, 1100, 1700, 2500 and 3750 cm−1, representing the CH, C-O, C=O, SH and OH groups respectively. The varying degree of transmittance and pH reported presents the selected R. stolonifer isolate as a biological entity for the synthesis of stable iron nanoparticles.
Synthesis, bioactivities and cytogenotoxicity of animal fur-mediated silver nanoparticles
Authors: Akintayo G O , Lateef A , Azeez M A , Asafa T B , Oladipo I C , Badmus J A , Ojo S A , Elegbede J A , Gueguim-Kana E B , Beukes L S , Yekeen T A 
Published: June 2020

Abstract
Animal waste materials are rarely used in the synthesis of nanoparticles compared to microorganisms and plant materials. The use of animal fur (goat) in synthesis could assist in turning waste to wealth. Thus, potentials of animal fur in the synthesis of silver nanoparticles (AF-AgNPs), its biological activities and safety through cytogenotoxicity were investigated. Animal fur (1 g) was hydrolyzed with 100 ml of 0.1 M NaOH at 90 °C for 1 h, cooled and centrifuged at 4000 rpm for 30 min. The extract (1 ml) was added to 1 mM AgNO3 (40 ml) to reduce Ag+ to its nanoparticles. The AF-AgNPs was characterized using UV–vis spectroscopy, Fourier-transform-infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and Energy Dispersive X-ray (EDX) analysis. Larvicidal, antioxidant, anticoagulant and thrombolytic potentials of AF-AgNPs were studied. Onion bulbs (20) were exposed to 0.01, 0.10, 1.0, 10.0 and 100.0 μg/ml of AF-AgNPs solution for its cytogenotoxicity study with AgNO3 solution and distilled water as controls. Microscopic (24, 48 and 72 h) assessment of the onion cells and macroscopic (72 h) evaluation of the roots were also studied. The AF-AgNPs solution was brownish with surface plasmon resonance at 419 nm. Evaluation of FTIR spectra showed that protein molecules were used as capping and stabilization agents. The AF-AgNPs had size range of 11.67-31.47 nm, caused 60-100% mortality of exposed Anopheles mosquito larvae in 12 h, and scavenged DPPH (40-59%) and hydrogen peroxide (75-94%). The nanoparticles also exhibited anticoagulant and thrombolytic potentials on human blood with 25% lysis compared to 13% observed for only extract. Various chromosomal aberrations and growth inhibition were induced by AF-AgNPs especially at 72 h of 100 μg/ml. Extract from animal fur was explored in biogenic synthesis of nanoparticles and found to have high potentials as antioxidant, anticoagulant, thrombolytic agents. Inhibition of cell growth observed especially at highest concentration can be explored in anticancer drugs though with caution due to AF-AgNPs potential to induce chromosomal aberrations.
Nanotechnology in the built environment for sustainable development
Authors: Elegbede JA , Lateef A 
Published: June 2020

Abstract
Nanotechnology as an emerging discipline of the 21st century has immense benefits for mankind due to the exceptional attributes of nanomaterials which can be used to render novel products and services. Amongst several fields of human endeavours, the built environment, largely composed of the disciplines of construction engineering, architecture, fine and applied arts, and urban and regional planning can make use of nanomaterials in creating green facilities with improved properties, aesthetics and innovation. Though there are reports of basic and applied investigations dealing with the production and evaluation of nanomaterials in the built environment, there is still a gap in harnessing the information together for the benefits of the practitioners in the built environment. Therefore, this treatise serves to x-ray the applications of nanotechnology in the built environment with the view of establishing nexus between the two areas. This compendium may stimulate the re-engineering of curricula in the built environment and stimulates new lines of research, product development and evaluation.
Research on Vibration Suppression for AGARD Wing Based on State Space Model
Authors: Liu Xiaoyan 
Published: June 2020

Abstract
Based on the Observer method, the unsteady aerodynamic reduced order model is established. The aerodynamic, structural and control parts are in the form of state space equations. The state feedback control law is designed by linear quadratic regulator (LQR) method, and the active flutter suppression of aeroelastic system is realized. The three-dimensional AGARD elastic wing is selected as an example. The simulation results show that the active control law designed by the model reduction technique can effectively stabilize the response of the system, and the critical speed of closed-loop flutter increases greatly.
Analysis of Over-Torque Failure Characteristic of Tool Joints
Authors: Chen Feng , Zhu Wei , Qinfeng Di , Wang Wenchang , Wang Nan , Jin Yuguo 
Published: June 2020

Abstract
Increasingly demanding drilling conditions and progressive drilling technology put forward new requirements for the torsion performance of tool joints. Over-torque failure of tool joints in downhole occurs frequently, resulting in huge economic losses. It is of great significance to analyze the mechanism of over-torque failure of the tool joint. This mechanism can help to selection of the tool joint and improve the design of the tool joint. In this paper, three dimensional elastic-plastic finite element models of single-shoulder tool joint and double-shoulder tool joint are established. Based on ABAQUS, the stress characteristics of tool joints under working torque are analyzed, and the mechanism of over-torque failure of API single-shoulder tool joints and double-shoulder tool joints is revealed. The result shows that there is a serious stress concentration phenomenon in both single-shoulder tool joints and double-shoulder tool joints, which restricts the performance of tool joint. The stress distribution of the tool joint should be homogenized in the design of the new type of tool joint, so as to improve the performance of the tool joint.
Electronic properties of [111] hydrogen passivated Ge nanowires with surface substitutional lithium
Authors: Arellano L G , Salazar F , Trejo Baños A , Miranda A , Pérez L A , Cruz-Irisson M 
Published: June 2020

Abstract
In this work, a density functional theory study of the lithium (Li) effects on the properties of hydrogenated germanium nanowires (H-GeNWs) is developed. In particular, the electronic band structures, densities of states, formation energies, and Li binding energies of H-GeNWs grown along the [111] crystallographic direction with a diamond structure for different concentrations of surface substitutional Li atoms were studied. Ge nanowires with hexagonal cross sections and three different diameters were considered. The results indicate that all studied H-GeNWs maintain a semiconducting behaviour and the size of the energy band gap is a function of the diameter and the concentration of substitutional surface Li atoms. The formation energy analysis reveals than the energy stability of the nanowires increases when the nanowire diameter and the concentration of Li atoms augment. The results of this work give insight of how the electronic properties of H-GeNWs change during the charging process and open the possibility to incorporate them as electrodes in Li-ion batteries.
Effects of Transition Zone on Magnetic Properties of Low Temperature Oxidation of Magnetite Particle:Comparison of Experiment and Micromagnetic Modeling
Authors: Ge K , Williams W 
Published: June 2020

Abstract
A relationship of hysteresis parameters and oxidation of ultrafine magnetic particles on both experimental measurements and micromagnetic simulations is obtained through a step-by-step oxidation of magnetite. Numerical simulations of hysteresis loop and microstructure of a core-shell geometry with transition zone using a multi-layer structure show two categories of behaviour for magnetic grains during oxidation. First, the SD (Single Domain, <70 nm) and lager SV (Single Vortex, >130 nm) particles remain unchanged ratio of saturation remanence to saturation magnetization (M
rs/M
s), and slightly decreased coercivity (B
c) during oxidation. Second, the fine SV particles (80 nm to 120 nm), the hysteresis parameters respectively increase and dramatic decrease at the early and late stage of oxidation, and the micromagnetic behaviors vary significantly. Finally the hysteresis parameters of larger SV particles remain nearly unchanged during oxidation. The predicted magnetic properties for the core-shell model exhibit better agreement with experimental data than that of previously used core-shell geometry (a stoichiometric core surrounded by an oxidized shell). It indicates that the magnetic properties of partially oxidized magnetic grains are controlled by the multi-layer coupling effects and can record paleomagnetic signals.
Reflection spectra of a thin-film GeSbTe diffraction grating on a silicon nitride waveguide
Authors: Minnullin R T , Sapegin A A , Makarov M E , Korolev D S , Yu Barabanenkov M 
Published: June 2020

Abstract
Recent advances in nanophotonics are due to the implication of new approaches to the photonic devices and components design, not only related to structural features, such as subwavelength periodic arrangements, but also new materials, e.g., phase-change materials like GeSbTe (GST) alloys. We consider recently proposed optical non-volatile GST memory cell with a GST diffraction grating instead of a continuous film placed on a silicon nitride waveguide. The grating allows diminishing the energy budget of an incident electromagnetic beam in case of an optically induced phase transition of GST due to excitation of the resonant guided mode in the grating. The excitation of this mode results in anomalous reflectance spectra of the waveguide-grating structure. Here, we present the reflection spectra of GST diffraction gratings on a silicon nitride waveguide calculated with the use of the matrix Riccati equation technique in the theory of multiple electromagnetic wave scattering in inhomogeneous media. We show how the reflection changes with variation of different parameters – grating period and height, incident wave polarization, and phase of the GST film.
Alterations of the Gut Microbiota in Patients With Coronavirus Disease 2019 or H1N1 Influenza
Authors: Gu Silan , Chen Yanfei , Wu Zhengjie , Chen Yunbo , Gao Hainv , Lv Longxian , Guo Feifei , Zhang Xuewu , Luo Rui , Huang Chenjie , Lu Haifeng , Zheng Beiwen , Zhang Jiaying , Yan Ren , Zhang Hua , Jiang Huiyong , Xu Qiaomai , Guo Jing , Gong Yiwen , Tang Lingling , Li Lanjuan 
Published: June 2020

AbstractBackgroundCoronavirus disease 2019 (COVID-19) is an emerging serious global health problem. Gastrointestinal symptoms are common in COVID-19 patients, and severe acute respiratory syndrome coronavirus 2 RNA has been detected in stool specimens. However, the relationship between the gut microbiome and disease remains to be established.MethodsWe conducted a cross-sectional study of 30 patients with COVID-19, 24 patients with influenza A(H1N1), and 30 matched healthy controls (HCs) to identify differences in the gut microbiota by 16S ribosomal RNA gene V3–V4 region sequencing.ResultsCompared with HCs, COVID-19 patients had significantly reduced bacterial diversity; a significantly higher relative abundance of opportunistic pathogens, such as Streptococcus, Rothia, Veillonella, and Actinomyces; and a lower relative abundance of beneficial symbionts. Five biomarkers showed high accuracy for distinguishing COVID-19 patients from HCs with an area under the curve (AUC) up to 0.89. Patients with H1N1 displayed lower diversity and different overall microbial composition compared with COVID-19 patients. Seven biomarkers were selected to distinguish the 2 cohorts (AUC = 0.94).ConclusionsThe gut microbial signature of patients with COVID-19 was different from that of H1N1 patients and HCs. Our study suggests the potential value of the gut microbiota as a diagnostic biomarker and therapeutic target for COVID-19, but further validation is needed.
Occurrence and Timing of Subsequent Severe Acute Respiratory Syndrome Coronavirus 2 Reverse-transcription Polymerase Chain Reaction Positivity Among Initially Negative Patients
Authors: Long Dustin R , Gombar Saurabh , Hogan Catherine A , Greninger Alexander L , O’Reilly-Shah Vikas , Bryson-Cahn Chloe , Stevens Bryan , Rustagi Arjun , Jerome Keith R , Kong Christina S , Zehnder James , Shah Nigam H , Weiss Noel S , Pinsky Benjamin A , Sunshine Jacob E 
Published: June 2020

Abstract
Using data for 20 912 patients from 2 large academic health systems, we analyzed the frequency of severe acute respiratory syndrome coronavirus 2 reverse-transcription polymerase chain reaction test discordance among individuals initially testing negative by nasopharyngeal swab who were retested on clinical grounds within 7 days. The frequency of subsequent positivity within this window was 3.5% and was similar across institutions.
Iron Deficiency Is Associated With Reduced Levels of Plasmodium falciparum-specific Antibodies in African Children
Authors: Bundi Caroline K , Nalwoga Angela , Lubyayi Lawrence , Muriuki John Muthii , Mogire Reagan M , Opi Herbert , Mentzer Alexander J , Mugyenyi Cleopatra K , Mwacharo Jedida , Webb Emily L , Bejon Philip , Williams Thomas N , Gikunju Joseph K , Beeson James G , Elliott Alison M , Ndungu Francis M , Atkinson Sarah H 
Published: June 2020

Abstract

Background
Iron deficiency (ID) and malaria are common causes of ill-health and disability among children living in sub-Saharan Africa. Although iron is critical for the acquisition of humoral immunity, little is known about the effects of ID on antibody responses to Plasmodium falciparum malaria.

Methods
The study included 1794 Kenyan and Ugandan children aged 0–7 years. We measured biomarkers of iron and inflammation, and antibodies to P. falciparum antigens including apical merozoite antigen 1 (anti-AMA-1) and merozoite surface antigen 1 (anti-MSP-1) in cross-sectional and longitudinal studies.

Results
The overall prevalence of ID was 31%. ID was associated with lower anti-AMA-1 and anti-MSP-1 antibody levels in pooled analyses adjusted for age, sex, study site, inflammation, and P. falciparum parasitemia (adjusted mean difference on a log-transformed scale (β) −0.46; 95 confidence interval [CI], −.66, −.25 P &lt; .0001; β −0.33; 95 CI, −.50, −.16 P &lt; .0001, respectively). Additional covariates for malaria exposure index, previous malaria episodes, and time since last malaria episode were available for individual cohorts. Meta-analysis was used to allow for these adjustments giving β −0.34; −0.52, −0.16 for anti-AMA-1 antibodies and β −0.26; −0.41, −0.11 for anti-MSP-1 antibodies. Low transferrin saturation was similarly associated with reduced anti-AMA-1 antibody levels. Lower AMA-1 and MSP-1-specific antibody levels persisted over time in iron-deficient children.

Conclusions
Reduced levels of P. falciparum-specific antibodies in iron-deficient children might reflect impaired acquisition of immunity to malaria and/or reduced malaria exposure. Strategies to prevent and treat ID may influence antibody responses to malaria for children living in sub-Saharan Africa.
Posttreatment Lymphopenia Is Associated With an Increased Risk of Redeveloping Nontuberculous Lung Disease in Patients With Mycobacterium avium Complex Lung Disease
Authors: Furuuchi Koji , Fujiwara Keiji , Uesgi Fumiko , Shimoda Masafumi , Seto Shintaro , Tanaka Yoshiaki , Yoshiyama Takashi , Yoshimori Kozo , Kurashima Atsuyuki , Ohta Ken , Morimoto Kozo 
Published: June 2020

Abstract

Background
Lymphopenia has been reported as a risk factor for poor prognosis in various infectious diseases, including Mycobacterium avium complex lung disease (MAC-LD), and recurrence in several infectious diseases. However, the association between lymphopenia and the risk of redeveloping nontuberculous lung disease (NTM-LD) after completed treatment for MAC-LD is unknown.

Methods
We performed a retrospective cohort study with 147 patients with MAC-LD who successfully completed guideline-based therapy. Lymphopenia was defined as an absolute lymphocyte count (ALC) &lt;1000 cells/μL based on commonly accepted reference values.

Results
During the median follow-up period of 41.9 months after treatment completion, 59 (40.1%) patients redeveloped NTM-LD. Patients with NTM-LD redevelopment had significantly lower posttreatment ALCs (median, 1260 vs 1420 cells/μL) than those without, and the univariate Cox proportional hazard analysis identified posttreatment ALC as a predictive factor for redevelopment (hazard ratio, .94 [95% confidence interval, .89–.99] for every increase of 100 cells/μL; P = .04). In the multivariate analysis, posttreatment ALC and the extent of bronchiectasis were independently associated with NTM-LD redevelopment. The cumulative rate of NTM-LD redevelopment was significantly higher in patients with posttreatment lymphopenia than in those without (P = .008).

Conclusions
Posttreatment lymphopenia could predict an increased risk of NTM-LD redevelopment after completed treatment for MAC-LD.
MRSA Transmission in Intensive Care Units: Genomic Analysis of Patients, Their Environments, and Healthcare Workers
Authors: Popovich Kyle J , Green Stefan J , Okamoto Koh , Rhee Yoona , Hayden Mary K , Schoeny Michael , Snitkin Evan S , Weinstein Robert A 
Published: June 2020

Abstract

Background
Methicillin-resistant Staphylococcus aureus (MRSA)—and now USA300 MRSA—is a significant intensive care unit (ICU) pathogen; healthcare worker (HCW) contamination may lead to patient cross-transmission.

Methods
From September 2015 to February 2016, to study the spread of MRSA, we enrolled HCWs in 4 adult ICUs caring for patients on MRSA contact precautions. Samples were collected from patient body sites and high-touch surfaces in patient rooms. HCW hands, gloves, and personal protective equipment were sampled pre/post-patient encounter. Whole genome sequencing (WGS) was used to compare isolates from patients, HCWs, and environment.

Results
There were 413 MRSA isolates sequenced (38% USA300, 52% USA100) from 66 patient encounters. Six of 66 HCWs were contaminated with MRSA prior to room entry. Isolates from a single patient encounter were typically either USA100 or USA300; in 8 (12%) encounters both USA300 and USA100 were isolated. WGS demonstrated that isolates from patients, HCWs, and environment often were genetically similar, although there was substantial between-encounter diversity. Strikingly, there were 5 USA100 and 1 USA300 clusters that contained similar strains (&lt;22 single-nucleotide variants [SNVs], with most &lt;10 SNVs) within the cluster despite coming from different encounters, suggesting intra- and inter-ICU spread of strains, that is, 4 of these genomic clusters were from encounters in the same ICU; 5 of 6 clusters occurred within 1 week.

Conclusions
We demonstrated frequent spread of MRSA USA300 and USA100 strains among patients, environment, and HCWs. WGS identified possible spread within and even between ICUs. Future analysis with detailed contact tracing in conjunction with genomic data may further elucidate pathways of MRSA spread and points for intervention.
The long and winding road of cardiomyocyte maturation
Authors: Maroli Giovanni , Braun Thomas 
Published: June 2020

AbstractKnowledge about the molecular mechanisms regulating cardiomyocyte (CM) proliferation and differentiation has increased exponentially in recent years. Such insights together with the availability of more efficient protocols for generation of CMs from induced pluripotent stem cells (iPSCs) have raised expectations for new therapeutic strategies to treat congenital and non-congenital heart diseases. However, the poor regenerative potential of the postnatal heart and the incomplete maturation of iPSC-derived CMs represent important bottlenecks for such therapies in future years. CMs undergo dramatic changes at the doorstep between prenatal and postnatal life, including terminal cell cycle withdrawal, change in metabolism, and further specialization of the cellular machinery required for high-performance contraction. Here, we review recent insights into pre- and early postnatal developmental processes that regulate CM maturation, laying specific focus on genetic and metabolic pathways that control transition of CMs from the embryonic and perinatal to the fully mature adult CM state. We recapitulate the intrinsic features of CM maturation and highlight the importance of external factors, such as energy substrate availability and endocrine regulation in shaping postnatal CM development. We also address recent approaches to enhance maturation of iPSC-derived CMs in vitro, and summarize new discoveries that might provide useful tools for translational research on repair of the injured human heart.