bluuebunny/crossref_metadata_2025 huggingface dataset:
The IFBMDA: A Model for Mechanical Design Automation
Authors: Lu Dongming , Sun Shouqian , He Zhijun
Published: March 2021

The IFBMDA is an Information-Flow-Based model for Mechanical Design Automation. This paper first analyzes the mechanical design process from the views of design methodology and cognitive model. Then, two essential assumptions about mechanical design behavior are provided. Based on the analysis and fundamental assumptions, this paper thoroughly describes five submodels which constitute the automation model IFBMDA. They are Information Flow model, Knowledge Processing model, Non-monotonic Expansion Search model, Iterative Constraint Generation and Solution model and Design Process Stage model. Then, this paper also evaluates the model in both practical and theoretical aspects and shows that it is well-developed in both aspects. Finally, the perspective of further mechanical design automation research is outlined.
Sensor Design for Automobile Air Bag Systems: Design Methods and Criteria
Authors: Chan Ching-Yao
Published: March 2021

Air bags are becoming a popular option chosen by the automobile manufacturers and also by the public to be installed on new cars sold in the United States. Sensors that detect crash occurrence play a fundamental role in the effectiveness of air bag systems. What properties of a vehicle should be sensed in a crash and used to activate an air bag system? How does a concept or method of crash sensing affect the design criteria? These issues are not only technically challenging but also closely related to the success of air bag technologies in millions of cars driven by the public.
Occupant Dynamic Responses for Evaluation of Compliance Characteristics of Aircraft Bulkheads
Authors: Lankarani Hamid M. , Ma Deren , Menon Rajiv
Published: March 2021

One important aspect of aircraft crashworthiness studies is to reduce head injuries to an aircraft occupant in case of a head contact with its surroundings. In view of the significance of this problem, studies of post-crash dynamic behavior of victims and the compliance characteristics of the aircraft bulkhead are necessary in order to reduce severe head injuries. Crash dynamics program SOM-LA/TA, incorporating a dynamic model of the human body with a finite element model of the seat structure was used. Modifications including development of more accurate contact force models and an occupant/seat envelope were performed in SOM-LA/TA. It was then used as an analytical tool for determination of the occupant response and the compliance characteristics of the bulkhead in various crash environments. Correlated studies of analytical simulations with impact sled test results were accomplished. It was observed that the code reasonably predicted the Head-Injury-Criteria (HIC) for the triangular-shaped pulses. A parametric study of the coefficients in the contact force model was then performed in order to obtain a correlation between the HIC and the coefficients in the contact force model. A measure of optimal values for the bulkhead compliances and displacement requirements was thus achieved in order to keep the possibility of head injury as little as possible. This information could in turn be used in the selection of suitable materials for the bulkhead, instrument panel, or interior walls of an aircraft.
Hertz Contact Force Model With Permanent Indentation in Impact Analysis of Solids
Authors: Lankarani Hamid M. , Nikravesh Parviz E.
Published: March 2021

A continuous analysis method for the direct-central impact of two solid particles is presented. Based on the assumption that local plasticity effects are the sole factor accounting for the dissipation of energy in impact, a Hertzian contact force model with permanent indentation is constructed. Utilizing energy and momentum considerations, the unknown parameters in the model are analytically evaluated in terms of a given coefficient of restitution and velocities before impact. The equations of motion of the two solids may then be integrated forward in time knowing the variation of the contact force during the contact period. For Illustration, an impact of two soft metallic particles is studied.
Exact Generation of Perpendicular Pipe Intersection Geometry
Authors: Amarnath C.
Published: March 2021

This paper describes an exact generator capable of generating the intersection geometry of perpendicular pipe joints. The resultant mechanism can be used for cutting of pipe ends for perpendicular intersection with other pipes.
Rotatability Laws for Spherical N-Bar Kinematic Chains
Authors: Liu Yung-Way , Ting Kwun-Lon
Published: March 2021

Ting’s rotatability laws of planar N-bar linkages are extended to spherical linkages. The paper proposed and proved theorems and criteria for spherical Kinematic chains (1) to provide the unique description, (2) to identify the assemblability condition, (3) to predict the revolvability between links, (4) to predict the full rotatatability, and (5) to provide a classification scheme and to identify the related characteristics. The criteria may also be applied to spatial nR3C linkages.
Practical Mobility Conditions for RSSR Mechanism
Authors: Lee Kyeong-Won , Seo Young-Jin , Yoon Yong-San
Published: March 2021

In this study, two sets of mobility conditions for a RSSR mechanism are developed to ensure the crank motion in the three dimensional four-bar mechanism. First set of the mobility conditions is the Grashof-type necessary conditions expressed only in terms of link lengths. The other set of the mobility conditions provides the necessary and sufficient conditions in analytic form accounting for the constraint of the deviation angle. For some special cases, the equations are simplified. The first set of equations may be useful in the initial design stage while the second set may be used for the final detail design. An example of mechanism is taken for the comparison of the analyses results.
The Geometric Generation of the Joint Loci of Spatial Dyads With Axis Joints
Authors: Nisbett J. Keith , Lawley T. J.
Published: March 2021

The geometric aspects of Burmester theory, as used in planar four-bar linkage synthesis, are examined to define a general procedure which is applied to the generation of the joint loci of spatial dyads with axis joints. The joints are geometrically related to the screw axes of the prescribed motion, by means of a screw triangle. The geometric relationships are typically separated into several geometric constraints. Each geometric constraint is considered separately to generate the loci of lines representing joint axes which satisfy the constraint. Combining the loci from each constraint produces a single loci of all the possible fixed or moving joints. The geometric approach is shown to have several benefits not obtained in numerical and pure analytical techniques, especially in relating the characteristics of the loci to the physical linkage and its required motion.
Integrated Mechanism and Control Approach for Minimum Flexural Vibrations in Slewing Space Structures
Authors: Yang L. F. , Chew M. , Juang J. N.
Published: March 2021

An integrated single-step approach to the synthesis of a mechanical device and a controller is presented. The mechanical device consists of a noncircular gear pair that acts as a varying gear ratio transmission between an electro-mechanical actuator and a flexible structure. Such a system has been introduced as an application in minimizing flexura] vibrations in the slewing maneuver of flexible space structures such as large solar panels and satellites in space. Only a simple regulator-type feedback controller is called for to control this complex electro-mechanical-and-structural system and the purpose is to design this complex system in an integrated procedure to achieve low flexural vibrations of the structure. Simulations of the slewing control tasks for two different flexible space structures are presented: a single planar flexible beam; and a planar flexible articulated double-beam.
Uptake of polymeric nanoparticles in a human induced pluripotent stem cell-based blood–brain barrier model: Impact of size, material, and protein corona
Authors: Onyema Helen N. , Berger Martin , Musyanovych Anna , Bantz Christoph , Maskos Michael , Freese Christian
Published: March 2021

The blood–brain barrier (BBB) maintains the homeostasis of the central nervous system, which is one of the reasons for the treatments of brain disorders being challenging in nature. Nanoparticles (NPs) have been seen as potential drug delivery systems to the brain overcoming the tight barrier of endothelial cells. Using a BBB model system based on human induced pluripotent stem cells (iPSCs), the impact of polymeric nanoparticles has been studied in relation to nanoparticle size, material, and protein corona. PLGA [poly(lactic-co-glycolic acid)] and PLLA [poly(d,l-lactide)] nanoparticles stabilized with Tween® 80 were synthesized (50 and 100 nm). iPSCs were differentiated into human brain microvascular endothelial cells (hBMECs), which express prominent BBB features, and a tight barrier was established with a high transendothelial electrical resistance of up to 4000 Ω cm2. The selective adsorption of proteins on the PLGA and PLLA nanoparticles resulted in a high percentage of apolipoproteins and complement components. In contrast to the prominently used BBB models based on animal or human cell lines, the present study demonstrates that the iPSC-based model is suited to study interactions with nanoparticles in correlation with their material, size, and protein corona composition. Furthermore, asymmetrical flow field-flow fractionation enables the investigation of size and agglomeration state of NPs in biological relevant media. Even though a similar composition of the protein corona has been detected on NP surfaces by mass spectrometry, and even though similar amounts of NP are interacting with hBMECs, 100 nm-sized PLGA NPs do impact the barrier, forming endothelial cells in an undiscovered manner.
Modelling laser ultrasound waveforms: The effect of varying pulse duration and material properties
Authors: Rajagopal Srinath , Cox Ben T.
Published: March 2021

Optical generation of ultrasound using nanosecond duration laser pulses has generated great interest both in industrial and biomedical applications. The availability of portable laser devices using semiconductor technology and optical fibres, as well as numerous source material types based on nanocomposites, has proliferated the applications of laser ultrasound. The nanocomposites can be deposited on the tip of optical fibres as well as planar hard and soft backing materials using various fabrication techniques, making devices suitable for a variety of applications. The ability to choose the acoustic material properties and the laser pulse duration gives considerable control over the ultrasound output. Here, an analytical time-domain solution is derived for the acoustic pressure waveform generated by a planar optical ultrasound source consisting of an optically absorbing layer on a backing. It is shown that by varying the optical attenuation coefficient, the thickness of the absorbing layer, the acoustic properties of the materials, and the laser pulse duration, a wide variety of pulse shapes and trains can be generated. It is shown that a source with a reflecting backing can generate pulses with higher amplitude than a source with an acoustically-matched backing in the same circumstances when stress-confinement has not been satisfied.
Carbohydrate Drink Use During 30 Minutes of Variable-Intensity Exercise Has No Effect on Exercise Performance in Premenarchal Girls
Authors: Heidorn C. Eric , Dykstra Brandon J. , Conner Cori A. , Mahon Anthony D.
Published: March 2021

Purpose: This study examined the physiological, perceptual, and performance effects of a 6% carbohydrate (CHO) drink during variable-intensity exercise (VIE) and a postexercise test in premenarchal girls. Methods: A total of 10 girls (10.4 [0.7] y) participated in the study. VO2peak was assessed, and the girls were familiarized with VIE and performance during the first visit. The trial order (CHO and placebo) was randomly assigned for subsequent visits. The drinks were given before VIE bouts and 1-minute performance (9 mL/kg total). Two 15-minute bouts of VIE were completed (10 repeated sequences of 20%, 55%, and 95% power at VO2peak and maximal sprints) before a 1-minute performance sprint. Results: The mean power, peak power, heart rate (HR), %HRpeak, and rating of perceived exertion during VIE did not differ between trials. However, the peak power decreased, and the rating of perceived exertion increased from the first to the second bout. During the 1-minute performance, there were no differences between the trial (CHO vs placebo) for HR (190 [9] vs 189 [9] bpm), %HRpeak (97.0% [3.2%] vs 96.6% [3.0%]), rating of perceived exertion (7.8 [2.3] vs 8.1 [1.9]), peak power (238 [70] vs 235 [60] W), fatigue index (54.7% [10.0%] vs 55.9% [12.8%]), or total work (9.4 [2.6] vs 9.4 [2.1] kJ). Conclusion: CHO supplementation did not alter physiological, perceptual, or performance responses during 30 minutes of VIE or postexercise sprint performance in premenarchal girls.
Mysterious eagle killer identified
Authors: Stokstad Erik
Published: March 2021

A new species of cyanobacteria that lives on invasive waterweed produces an unusual neurotoxin
Response to Comment on “Large-scale GWAS reveals insights into the genetic architecture of same-sex sexual behavior”
Authors: Ganna Andrea , Verweij Karin J. H. , Nivard Michel G. , Maier Robert , Wedow Robbee , Busch Alexander S. , Abdellaoui Abdel , Guo Shengru , Sathirapongsasuti J. Fah ,   23andMe Research Team, Lichtenstein Paul , Lundström Sebastian , Långström Niklas , Auton Adam , Harris Kathleen Mullan , Beecham Gary W. , Martin Eden R. , Sanders Alan R. , Perry John R. B. , Neale Benjamin M. , Zietsch Brendan P.
Published: March 2021

Hamer
et al
. argue that the variable “ever versus never had a same-sex partner” does not capture the complexity of human sexuality. We agree and said so in our paper. But Hamer
et al
. neglect to mention that we also reported follow-up analyses showing substantial overlap of the genetic influences on our main variable and on more nuanced measures of sexual behavior, attraction, and identity.
At the beginning of speciation
Authors: Jarvis Erich D.
Published: March 2021

Appearance and song are sexually selected factors to maintain a new bird species
Getting excited about cycloadditions
Authors: Schmidt Valerie A.
Published: March 2021

Photoactivation to long-lived triplet excited states enables cycloadditions with heteroarenes
mRNA vaccination boosts cross-variant neutralizing antibodies elicited by SARS-CoV-2 infection
Authors: Stamatatos Leonidas , Czartoski Julie , Wan Yu-Hsin , Homad Leah J. , Rubin Vanessa , Glantz Hayley , Neradilek Moni , Seydoux Emilie , Jennewein Madeleine F. , MacCamy Anna J. , Feng Junli , Mize Gregory , De Rosa Stephen C. , Finzi Andrés , Lemos Maria P. , Cohen Kristen W. , Moodie Zoe , McElrath M. Juliana , McGuire Andrew T.
Published: March 2021

Boosterism could save lives

Postinfection immune protection against severe acute respiratory syndrome coronavirus 2 reinfection is not fully understood. It will be devastating if waves of new variants emerge that undermine natural immune protection. Stamatatos
et al.
investigated immune responsiveness 4 to 8 months after previously infected individuals were given a messenger RNA–based vaccine developed for the original Wuhan variant (see the Perspective by Crotty). Before vaccination, postinfection serum antibody neutralization responses to virus variants were variable and weak. Vaccination elevated postinfection serum-neutralizing capacity approximately 1000-fold against Wuhan-Hu-1 and other strains, and serum neutralization against the variant B.1.351 was enhanced. Although responses were relatively muted against the variant, they still showed characteristic memory responses. Vaccination with the Wuhan-Hu-1 variant may thus offer a valuable boost to protective responses against subsequent infection with variant viruses.

Science
, abg9175, this issue p.
1413
; see also abj2258, p.
1392
Reckoning with Asian America
Authors: Lee Jennifer , Huang Tiffany J.
Published: March 2021

It took the mass murder of six Asian women in Atlanta last week to draw national attention to what Asian Americans have been warning about since the wake of the pandemic: anti-Asian violence. The incident reflects an under-recognized history of anti-Asian violence and discrimination in this country that dates back more than 150 years. This needs to change. Asian Americans must become central to the discourse on race in America. For the country to “care” about the outcry by Asian Americans, the public needs to understand how America got to this point.
Effects of Peroxyacetic Acid Spray and Storage Temperature on the Microbiota and Sensory Properties of Vacuum-Packed Subprimal Cuts of Meat
Authors: Yang Xianqin , Wang Hui , Hrycauk Scott , Klassen Mark D.
Published: March 2021

The findings of this study show that PAA solutions applied at low concentrations under commercial settings positively modulated the meat microbiota. It did not have bactericidal effects for beef subprimals with very low microbial loads.
An Update on Gender Parity Trends for Invited Speakers at Four Prominent Virology Conference Series
Authors: Palmenberg Ann C. , Kalejta Robert F.
Published: March 2021

Historically, men rather than women have been selected for invited speaking positions at the four prominent virology conference series we have followed since the 1980s. However, the low ratio of female representation in most earlier years (20% in 1982 to 2010) has shown encouraging improvement (37% in 2011 to 2017), particularly over the last few years (48% in 2018 to 2020).
Supplemental Material: Latest Quaternary slip rates of the San Bernardino strand of the San Andreas fault, southern California, from Cajon Creek to Badger Canyon
Authors: McGill S.F. , al. et
Published: March 2021

Additional details on methods and for descriptions and interpretations of geologic units at the Badger Canyon site. Additional trench logs and photographs showing locations of dated samples that were not shown in other figures. Tables providing latitude and longitude for all dated samples, as well as field and lab data for terrestrial nuclide dating and complete soil descriptions.
Marine sedimentary records of chemical weathering evolution in the western Himalaya since 17 Ma
Authors: Zhou Peng , Ireland Thomas , Murray Richard W. , Clift Peter D.
Published: March 2021

The Indus Fan derives sediment from the western Himalaya and Karakoram. Sediment from International Ocean Discovery Program drill sites in the eastern part of the fan coupled with data from an industrial well near the river mouth allow the weathering history of the region since ca. 16 Ma to be reconstructed. Clay minerals, bulk sediment geochemistry, and magnetic susceptibility were used to constrain degrees of chemical alteration. Diffuse reflectance spectroscopy was used to measure the abundance of moisture-sensitive minerals hematite and goethite. Indus Fan sediment is more weathered than Bengal Fan material, probably reflecting slow transport, despite the drier climate, which slows chemical weathering rates. Some chemical weathering proxies, such as K/Si or kaolinite/(illite + chlorite), show no temporal evolution, but illite crystallinity and the chemical index of alteration do have statistically measurable decreases over long time periods. Using these proxies, we suggest that sediment alteration was moderate and then increased from 13 to 11 Ma, remained high until 9 Ma, and then reduced from that time until 6 Ma in the context of reduced physical erosion during a time of increasing aridity as tracked by hematite/goethite values. The poorly defined reducing trend in weathering intensity is not clearly linked to global cooling and at least partly reflects regional climate change. Since 6 Ma, weathering has been weak but variable since a final reduction in alteration state after 3.5 Ma that correlates with the onset of Northern Hemispheric glaciation. Reduced or stable chemical weathering at a time of falling sedimentation rates is not consistent with models for Cenozoic global climate change that invoke greater Himalayan weathering fluxes drawing down atmospheric CO2 but are in accord with the idea of greater surface reactivity to weathering.
Effect of PCI of culprit and non-culprit lesions for patients with STEMI compared with culprit lesion-only PCI
Authors: Magavern Emma , Khong Teck K
Published: March 2021

Commentary on:Mehta SR, Wood DA, Storey RF,et al. Complete Revascularization with Multivessel PCI for Myocardial Infarction.N Engl J Med2019; 381:1411–21.

Commentary by:Dr Emma Magavern and Dr Teck Khong Clinical Pharmacology, St George’s, University of London, UK.

Series Editor:Dr Teck Khong, DTB Associate Editor Clinical Pharmacology, St George’s, University of London, UK.
Reduced membrane cholesterol content in skeletal muscle is not essential for greater insulin-stimulated glucose uptake after acute exercise by rats
Authors: Wang Haiyan , Arias Edward B. , Cartee Gregory D.
Published: March 2021

One exercise session can elevate insulin-stimulated glucose uptake (GU) by skeletal muscle, but it is uncertain if this effect is accompanied by altered membrane cholesterol content, which is reportedly inversely related to insulin-stimulated GU. Muscles from sedentary (SED) or exercised 3 h post-exercise (3hPEX) rats were evaluated for GU, membrane cholesterol, and phosphorylation of cholesterol regulatory proteins (pHMCGRSer872 and pABCA1Ser2054). Insulin-stimulated GU for 3hPEX exceeded SED. Membrane cholesterol, pHMCGRSer872 and pABCA1Ser2054 did not differ between groups.

Novelty: Alterations in membrane cholesterol and phosphorylation of proteins that regulate muscle cholesterol are not essential for elevated insulin-stimulated GU in skeletal muscle after acute exercise.
Regional variation in wood discoloration in paper birch trees
Authors: Giroud Guillaume , Duchateau Emmanuel , Auger Isabelle , Havreljuk Filip , Barrette Julie
Published: March 2021

Wood discoloration was investigated in 721 paper birch (Betula papyrifera Marsh.) trees from 146 sites across the managed forest of Quebec, Canada. Discoloration was present at breast height in 85% of trees, but its impact was limited in terms of tree basal area and volume, with proportions of 6.4% and 3.6%, respectively. These two measures were strongly correlated. Discoloration changed wood appearance but had no effect on microfibril angle and modulus of elasticity. Discolored wood was nevertheless denser, probably due to the accumulation of colored extractives. Predictive models were also developed and applied to 415 711 paper birch trees from 51 689 inventory plots across the province to study regional variation. Higher proportions of discolored basal area were obtained in the southwestern areas of the province where the climate is warmer and drier. In these areas, paper birch trees are larger and, likely, support bigger branches which can cause larger columns of discoloration when broken. Lower proportions were found in eastern regions where snowfall is more abundant. Smaller, more flexible branches in trees growing in these areas could explain this result. This study confirms the feasibility of large-scale mapping of wood discoloration in standing trees based on forest inventory and climate data.
Refining anticipation of degraded bone microstructures during osteoporosis based on statistical homogenized reconstruction method via quality of connection function
Authors: Famouri Seyedfarzad , Bagherian Amirhossein , Shahmohammadi Armin , George Daniel , Baghani Mostafa , Baniassadi Majid
Published: March 2021

Nowadays, osteoporosis disease that is related to aging has become a proliferating problem in worldwide society. It is therefore crucial to understand its evolution and predict this phenomenon precisely for different types of bone and volume fractions with adequate mathematical model. The application of statistical reconstruction method would be a helpful tool to predict osteoporosis for the simplified bone microstructures. To model osteoporosis evolution over time, in a first step, we propose to degrade the volume fraction with a mathematical model to reach any determined volume fraction between the initial condition and the degraded one with a statistical interpolation. In a second step, the degraded microstructure will be optimized using a statistical descriptor. The final optimized microstructures will be discussed as a function of the effective mechanical properties. The capability of quality of connection and two-point correlation functions (TPCFs) in 3D models and their application in the optimization of reconstructed interpolated models are going to be demonstrated. Finally, we will demonstrate and discuss the advantages of using the Quality of Connection Function (QCF) as a replacement of TPCF over the sole statistical descriptor named TPCF. We will show that QCF descriptor is better than TPCF only to find the optimized reconstructed models in a determined volume fraction.
Time-Invariant Superfluid Quantum Space as the Unified Field Theory
Authors: Šorli Amrit S. , Čelan Štefan
Published: March 2021

The novelty of 21st-century physics is the development of the “superfluid quantum vacuum” model, also named “superfluid quantum space” that is replacing space-time as the fundamental arena of the universe. It also represents the model that has the potential of unifying four fundamental forces of the universe. Superfluid quantum space is represented as the time-invariant fundamental field of the universe where time is merely the duration of material changes.
Depositional sequences in northern Peru: new insights on the palaeogeographic and palaeotectonic reconstruction of western Gondwana during late Permian and Triassic
Authors: Carrillo Emilio , Barragán Roberto , Hurtado Christian , Calderón Ysabel , Martín Germán , Vázquez-Taset Yaniel , Parra Mauricio , Rivera Ariana , Cadena Fanny Mariela , Sarmiento Luis
Published: March 2021

Late Permian to Early Jurassic strata in northern Peru allow us to carry out a seismostratigraphic, lithotectonic and chemostratigraphic analysis connecting the Andean–Amazonian foreland basins of Huallaga, Ucayali, southern Marañón and the Eastern Cordillera. This analysis and data integration from Ecuador to western Brazil and southern Peru and Bolivia allow us to redefine the timing of the major documented tectonic phases and corresponding palaeogeographies of western Gondwana from the late Permian to the Triassic. Three lithotectonic sequences and four associated deformation stages are recognized: (1) A sequence, tectonic relaxation, during the late Permian; (2) A–B intra-sequence, folding-and-thrusting attributed to a continuation in time of the Gondwanide Orogeny, during the Early to Middle Triassic; (3) B sequence, rifting, attributed to Gondwana breakup during the Middle and late Triassic; (4) C sequence, thermal sag, during the Late Triassic. Evaporites and carbonates (A sequence) dominated a low-subsidence basin with southern restricted marine inflow at the Permian–Triassic boundary. A novel palaeogeographic model for these evaporites suggests that this saline basin extended up to 50 000 km
2
in a restricted environment area with a potential bullseye pattern. The last pulse of the Gondwanide Orogeny and associated fold and thrust belt (A–B intra-sequence) exhumed prior to the sequence, generating emerged areas with little to no sedimentation. Red beds (B sequence) characterize the rifting stage, representing the syn-depositional infill of continental grabens, likely extending to the Acre Basin in Brazil. Finally, during the thermal sag, a marine inflow likely from the northwestern part of Peru generated sedimentation of carbonates and evaporites (C Sequence) to the west and east of the Peruvian margin. This sediment differentiation was, in part, controlled by the existence of pre-existing grabens associated with the previous rifting stage. This interpretation, together with other evaporitic occurrences, attributed here to a Late Triassic epoch in south and north Peru and west Brazil, suggest the existence of an evaporitic basin filling an undeformed area of probably
c.
 170 000 km
2
. It is therefore suggestive of the existence of a Late Triassic (Norian to Rhaetian; 217 to 204 Ma) salt giant controlled by thermal sag in western Gondwana. Our results are of great relevance for any future interpretation related to mass extinctions, palaeoclimatic analysis and ocean dynamics during the Permian and Triassic as well as natural resource distribution between Ecuador and Bolivia.
The relationship between strength and abrasion characterizations in granite building stones
Authors: Cheshomi A. , Moradizadeh M.
Published: March 2021

The wear of cutting blades during the preparation of building stones is an inevitable issue that occurs as a result of the contact of the blade with rock components. The present study aims to investigate the feasibility of proposing experimental relations of strength parameters and mineralogical hardness with Cerchar and Laboratoires Central des Ponts et Chaussées France (LCPC) tests. For this purpose, 18 samples of granite building stones were selected and equivalent quartz content (EQC), compressive and Brazilian tensile strength (uniaxial compressive strength (UCS) and Brazilian tensile strength (BTS)), and Cerchar and LCPC abrasivity indices (CAI and LAC) were determined. The results showed the lack of any significant relationship between strength and abrasion properties. However, when evaluating the simultaneous impact of EQC and UCS using the rock abrasion index (

RAI

=

UCS

×
EQC

), significant valid empirical RAI–CAI and RAI–LAC relationships were derived. To investigate the simultaneous effect of UCS, BTS and EQC, a dimensionless parameter (i.e. modified rock abrasion index;

MRAI

=
(

UCS

/

BTS

)
×

EQC

) was introduced. Moreover, it was found that the empirical MRAI–CAI relationship was more significant and valid than the previous relations. Verification of the proposed relationship with the values of other researchers and six new samples for estimating CAI and LAC based on UCS, BTS and EQC was found to be highly accurate for granite building stones.
In Situ Lithiated ALD Niobium Oxide for Improved Long Term Cycling of Layered Oxide Cathodes: A Thin-Film Model Study
Authors: Aribia Abdessalem , Sastre Jordi , Chen Xubin , Gilshtein Evgeniia , Futscher Moritz H. , Tiwari Ayodhya N. , Romanyuk Yaroslav E.
Published: March 2021

Protective coatings applied to cathodes help to overcome interface stability issues and extend the cycle life of Li-ion batteries. However, within 3D cathode composites it is difficult to isolate the effect of the coating because of additives and non-ideal interfaces. In this study we investigate niobium oxide (NbOx) as cathode coating in a thin-film model system, which provides simple access to the cathode-coating-electrolyte interface. The conformal NbOx coating was applied by atomic layer deposition (ALD) onto thin-film LiCoO2 cathodes. The cathode/coating stacks were annealed to lithiate the NbOx and ensure sufficient ionic conductivity. A range of different coating thicknesses were investigated to improve the electrochemical cycling with respect to the uncoated cathode. At a NbOx thickness of 30 nm, the cells retained 80% of the initial capacity after 493 cycles at 10 C, more than doubling the cycle life of the uncoated cathode film. Elemental analysis using TOF-SIMS and XPS revealed a bulk and surface contribution of the NbOx coating. These results show that in situ lithiated ALD NbOx can significantly improve the performance of layered oxide cathodes by enhancing interfacial charge transfer and inhibiting surface degradation of the cathode, resulting in better rate performance and cycle life.
Electrochemical Sensing of 1-hydroxypyrene on a Colloidal Gold Modified Zeolitic Imidazolate Frameworks-67/Carbon Nanofiber Paste Electrode
Authors: Li Yuan , Li Yutong , Du Chao , Zhang Pengju , Cen Peipei , Liu Xinsheng , Li Yonghong
Published: March 2021

Urinary 1-hydroxypyrene (1-OHP) is generally used as an exposure biomarker of polycyclic aromatic hydrocarbons (PAHs). In this work, a colloidal gold modified zeolitic imidazolate frameworks-67/carbon nanofiber paste electrode (Au@ZIF-67/CNFPE) was fabricated for the rapid and sensitive detection of 1-OHP. The morphologies of carbon nanofibers (CNF), ZIF-67, colloidal gold and colloidal gold@ZIF-67 (Au@ZIF-67) were studied by transmission electron microscopy (TEM). The electrochemical behavior of 1-OHP was investigated by square wave voltammetry (SWV). The effect factors like pH value, amount of colloidal gold, accumulation potential and accumulation time have been optimized. Under the optimal conditions, the constructed sensor responded to 1-OHP linearly in the concentration range of 0.0005–10 μM, and the detection limit was 0.1 nM. The reproducibility, stability and selectivity of this sensor were also examined. Finally, the electrode was successfully applied for the analysis of 1-OHP in human urine samples.
Effect of Catalyst and Catalyst Layer Composition on Catalyst Support Durability
Authors: Komini Babu Siddharth , Mukundan Rangachary , Wang Chunmei , Langlois David , Cullen David A. , Papadias Dennis , More Karren L. , Ahluwalia Rajesh , Waldecker Jim , Borup Rodney
Published: March 2021

Polymer electrolyte membrane fuel cells (PEMFCs) are efficient, zero-emission engines for the automotive sector. However, cost and durability are major barriers for the commercialization of PEMFCs. Degradation of the carbon support in the cathode catalyst layer due to high potential excursions caused by unmitigated events like H2 starvation, or start-up/shutdown are still a major durability issue in PEMFCs. Catalyst support durability was studied by accelerated stress tests (ASTs) that included repeated potential cycling from 1.0 to 1.5 V. The effect of catalyst layer composition on carbon corrosion was studied using membrane electrode assemblies with different catalysts (Pt, PtCo), catalyst composition (catalyst wt.%, supports), ionomer composition (loading, and equivalent weights). The corrosion of the carbon support is similar between Pt and PtCo catalysts. However, the performance degradation rate is higher for the alloy catalysts due to differences in catalyst particle size and the transition metal’s leaching accelerating the performance degradation. The carbon loss is lower for catalysts with lower initial carbon loading (or higher catalyst wt.%), which is better for durability. However, the cumulative loss of carbon is identical for electrodes with the same catalyst support irrespective of catalyst and ionomer composition in the catalyst layer.
Modeling cerebral blood flow and ventilation instability due to CO2
Authors: Yamashiro Stanley M. , Kato Takahide
Published: March 2021

Prior models of brain blood flow and respiratory control have not focused on instability. Time varying time delay resulting from brain blood flow changes due to carbon dioxide (CO2) and peripheral chemoreceptor gain were predicted to be important determinants of instability due to nonlinear interaction in addition to linear control loop gain. Time delay was assumed to be set by the ratio of brain arterial vascular volume and blood flow. This vascular volume was predicted to also significantly change with CO2.
Payment Scheduling Problem with Multiple Modes for Activities to Maximize the Net Present Value of a Project
Authors: Ghasedi Somayeh , Afshar-Nadjafi Behrouz
Published: March 2021

In this paper, the multimode payment scheduling project is studied, which aims to maximize the net present value (NPV) of a project by deciding on payments and the start times of its activities. The problem is formulated mathematically from the point of view of the selected contractor of the project. In the proposed model, a bonus and penalty structure is considered, in which the project’s activities can be performed through different execution modes. Another interesting feature of the developed model is the possibility of switching between the execution’s modes during the implementation of each activity, which can increase the NPV. Because of the proposed model’s computational complexity, two metaheuristic algorithms are developed to tackle the underlying problem. In order to evaluate the performance of the developed algorithms, a set of 108 test instances are solved, and the computational results confirm the applicability of the solving methodologies.
EPHA2 Promotes the Invasion and Migration of Human Tongue Squamous Cell Carcinoma Cal‐27 Cells by Enhancing AKT/mTOR Signaling Pathway
Authors: Wang Fengqin , Zhang Hanzhong , Cheng Zhigang
Published: March 2021

EPHA2 is a member of the ephrin receptor tyrosine kinase family and is closely related to the malignant tumor progression. The effect of EPHA2 on OSCC is not clear. This study explored the role of EPHA2 and AKT/mTOR signaling pathways in Cal‐27 cell invasion and migration. The expression of EPHA2 and EPHA4 in human OSCC and normal oral tissue was detected by immunohistochemistry. EPHA2‐overexpressing and EPHA2‐knockdown Cal‐27 cells were established, and the cells were treated with an AKT inhibitor (MK2206) and mTOR inhibitor (RAD001). The expression of EPHA2 was detected by qRT‐PCR, cell proliferation was evaluated by MTT assay, cell migration and invasion were examined by scratch and Transwell assay, and cell morphology and apoptosis were assessed by Hoechst 33258 staining. Western blot was performed to detect the expression of proteins related to AKT/mTOR signaling, cell cycle, and pseudopod invasion. EPHA2 and EPHA4 were highly expressed in clinical human OSCC. Overexpression of EPHA2 promoted the proliferation, migration, and invasion of Cal‐27 cells, inhibited cell cycle blockage and apoptosis, and enhanced the activity of the AKT/mTOR signaling pathway. MK2206 (AKT inhibitor) and RAD001 (mTOR inhibitor) reversed the effect of EPHA2 overexpression on the biological behavior of Cal‐27 cells. EPHA2 promotes the invasion and migration of Cal‐27 human OSCC cells by enhancing the AKT/mTOR signaling pathway.
Coexistence Analysis of D2D‐Unlicensed and Wi‐Fi Communications
Authors: Wang Ganggui , Wu Celimuge , Yoshinaga Tsutomu , Yin Rui , Murase Tutomu , Yau Kok-Lim Alvin , Bao Wugedele , Ji Yusheng
Published: March 2021

By enabling direct communications between nearby user equipment (UE), device‐to‐device (D2D) communication has become one of the key technologies in 5th generation (5G) mobile networks. D2D communication brings new communication opportunities for mobile devices, especially in a highly dense network. In this paper, D2D communication in the unlicensed spectrum, namely, D2D‐Unlicensed (D2D‐U), is discussed. The use of unlicensed frequency bands can ease the shortage of spectrum resources and improve network performance. However, the D2D‐U in 5G has significant effects on the network performance of existing unlicensed networks sharing the same frequency bands, such as Wi‐Fi and Bluetooth. Therefore, it is necessary to design a fair coexistence scheme for D2D‐U. To understand the coexistence problem, in this paper, we first formulate the network performance of D2D‐U and Wi‐Fi under two different coexistence schemes, namely, listen before talk (LBT) and duty cycle mechanism (DCM). Then, we use computer simulations to investigate a mode selection scheme that switches between these two schemes and point out the best possible solution for the coexistence between D2D‐U and Wi‐Fi.
Bilateral Reverse Total Shoulder Arthroplasty with Soft Tissue Release for Bilateral Posterior Fracture Dislocation after Status Epilepticus
Authors: El Rassi George , Dib Nabil , Maalouly Joseph , Moukarzel Rita , Aouad Dany
Published: March 2021

Proximal humerus fracture is a common orthopedic presentation, with bimodal age distribution. On the other hand, bilateral proximal humerus fracture dislocation is a rarely reported pathology, especially when it is not the result of direct trauma. We present a case of a 71-year-old female patient found to have simultaneous bilateral 4-part proximal humerus fractures following status epilepticus treated surgically with bilateral reverse shoulder arthroplasty with constraint and soft tissue release. In a patient with recurrent status epilepticus episodes, the combination of constrained reverse shoulder arthroplasty and the extensive soft tissue release should decrease the rate of failure and dislocation dramatically. We conclude, after reviewing the literature, that there is no straightforward algorithm for treating such patients and that a clear classification should take into account both bone quality and patient comorbidities which has yet to be developed.
Resveratrol Alleviates Vascular Endothelial Damage Caused by Lower-Extremity Ischemia Reperfusion (I/R) through Regulating Keap1/Nrf2 Signaling-Mediated Oxidative Stress
Authors: Song Xiaojun , Liu Zhili , Zeng Rong , Shao Jiang , Zheng Yuehong , Ye Wei
Published: March 2021

The present study aims to investigate the protective effects of Resveratrol (RSV) against vascular endothelial damage caused by lower-extremity I/R and the underlying preliminary mechanism. The in vitro hypoxia reoxygenation (HR) model was established on HUVECs. Lower-extremity I/R model was established on rats followed by being treated with RSV and the pathological state of artery was evaluated by HE and EVG staining, while the apoptotic state of artery was detected by TUNEL assay. The cell viability was detected by MTT assay and the apoptotic state of cells was determined by Hoechst test and flow cytometry assay. DCFH-DA staining was used to measure the level of ROS and the production of MDA and SOD was measured by commercial kits. The expression level of Nrf2, Keap1, HO-1, Bcl-2, Bax, and Caspase-3 in cells was determined by Western blot. Nrf2 was knocked down by siRNA technology. Overall, our data indicated that increased cell viability, declined apoptotic rate, and alleviated oxidative stress were observed in RSV treated HR HUVECs, which were significantly reversed by knocking down Nrf2. Animal experiment revealed that the pathological and apoptotic state of femoral artery were dramatically ameliorated by the treatment of RSV, accompanied by the alleviated oxidative stress, which were abolished by the co-administration of ML385, an inhibitor of Nrf2. Taken together, our data revealed that RSV might alleviate vascular endothelial injury induced by lower-extremity I/R injury through regulating Keap1/Nrf2 signaling-mediated oxidative stress.
Nutrition Knowledge among College of Basic Education Students in Kuwait: A Cross-Sectional Study
Authors: Husain Wafaa , Ashkanani Fatemah , Al Dwairji Maryam A.
Published: March 2021

Lack of nutrition knowledge may contribute to poor dietary practices. Schools are an ideal environment to address this issue and to start the process of nutrition education. Therefore, teachers should be equipped with adequate nutrition knowledge. This study was designed to evaluate the level of general nutrition knowledge and demographic variations in knowledge in a sample of students attending the College of Basic Education in Kuwait. A cross-sectional study was conducted using a modified and validated revised version of the General Nutrition Knowledge Questionnaire (GNKQ-R) for UK adults. Univariate and multivariate analyses were performed to determine the association between various factors and nutrition knowledge score. A total of five hundred and ninety-seven students completed the questionnaire. Most respondents (84.1%) had a poor level of nutrition knowledge using original Bloom’s cutoff points. Sex, BMI, cooking habits, and who is responsible for preparing food in the household were the main determinants of nutrition knowledge score atp < 0.05. The mean score of the students was 40.06 ± 9.89 out of 84 points. Females scored significantly higher than males, at 41.10 ± 9.29 and 38.72 ± 10.48, respectively (p = 0.007). Students with a BMI of ≥30 achieved significantly greater scores (mean 42.30 ± 9.41) than those who were underweight, normal, or overweight (p < 0.001). Students who stated that they always cook their own food achieved significantly greater scores (mean 43.69 ± 9.58) than those who did not (p = 0.025). Students who stated that they depend on the housekeeper for food preparation achieved significantly lower scores (mean 38.86 ± 10.13) than those who prepare their own food or depend on their relatives to prepare food (p = 0.042). Poor nutrition knowledge was found among prospective teachers studying in the College of Basic Education. This must be rectified for the effective implementation of nutrition education programs in schools.
Greenhouse Gas Emissions and Mitigation Measures within the Forestry and Other Land Use Subsector in Malawi
Authors: Missanjo Edward , Kadzuwa Henry
Published: March 2021

Analysing past trends of greenhouse gas (GHG) emissions remains indispensable to the understanding of current GHG emissions, thereby enabling prediction of future emissions as well as development of their mitigative pathways. This study quantified GHG emissions within the Forest and Other Land Use (FOLU) subsector in Malawi for the period 2011 to 2020. Results indicate that Malawi’s GHG emissions in the FOLU subsector fluctuated but decreased by 0.84 MtCO2e (13%) from 2011 to 2020, averaging to −1.3% annually. The GHG emissions of different categories within the subsector were highly significant (

p
<
0.001

) and contributed the highest (99.72%) of the total variation. Forestland contributed the highest (74%) of the subsector category emissions, followed by biomass burning (19%). The uncertainties for the estimated GHG emissions were low (<15%). This shows that the estimated GHG emissions within the FOLU subsector were significantly minimised. Notable interventions that have abated the emissions include afforestation and natural/assisted regeneration; protection and conservation of protected areas through the REDD+ mechanism; establishment of seed banks for raising drought-tolerant tree species; and breeding of fast-growing and drought-tolerant tree species; as well as screening of disease and pest-resistant species and promotion of biological control.
Role of Cholecystectomy in Symptomatic Hyperkinetic Gallbladder Patients
Authors: Singh Jai P.
Published: March 2021

Introduction. Biliary dyskinesia is defined by a gallbladder ejection fraction (EF) of less than 35% on HIDA scan, and these patients have shown a good response to cholecystectomy. Management of patients with biliary colic symptoms who have a hyperkinetic gallbladder (

EF
>
80
%

) is not clearly defined. Herein, I report three cases of the symptomatic hyperkinetic gallbladder that were successfully managed with cholecystectomy. Case Report. Patient 1was a 56-year-old female presented with pain in the right upper abdomen for one month. Her workup was unremarkable except for the gallbladder EF of 86%. Patient 2 was a 33-year-old female with similar symptoms and workup with gallbladder EF of 97%. Patient 3 was a 20-year-old female with right upper abdominal pain and gallbladder EF of 91%. Patients 1 and 3 had the normal US, normal CT scan, and normal EGD. Patient 2 had normal US and CT but did not undergo EGD. All three patients underwent laparoscopic cholecystectomy and had complete resolution of their symptoms. Conclusion. The hyperkinetic gallbladder is a rare phenomenon, which can cause debilitating right upper quadrant pain. All three patients had an excellent response to cholecystectomy. Therefore, it is concluded that the patients with biliary colic and gallbladder EF of 80% or higher should be strongly considered for surgery.