bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigating the water lubrication characteristics of sisal fiber reinforced ultrahigh‐molecular‐weight polyethylene material
Authors: Xie Xin , Guo Zhiwei , Yuan Chengqing 
Published: September 2020

AbstractThe ultrahigh‐molecular‐weight polyethylene (UHMWPE) has become the most widely used material for water‐lubricated bearings. In the research, the effects of introducing sisal fiber (SF) filler materials on the friction and wear characteristics of UHMWPE‐based composites were investigated. The composites were tested against the QSn7‐0.2 copper disc, under water‐lubricated conditions, using a specially designed testing apparatus. The purpose was to identify an improved material which could be used in water‐lubricated bearings. Four types of composites were tested under different sliding velocities and applied loads, which included pure UHMWPE and 10, 20, and 30 wt% SF reinforced UHMWPE. The friction coefficient and wear amount were measured to characterize the tribological properties of these composite materials. Moreover, in order to reveal the primary mechanism involved in friction and wear, various surface characterization techniques were adopted on the surface of composite materials. The analysis results showed that the addition of SF can stabilize the frictional properties and increase the water absorption of SF/UHMWPE composites. Furthermore, the use of a proper percentage of SF can discharge the wear debris, improve the loading capacity, and reduce adhesion wear. The adding of 10% SF in UHMWPE had produced the best anti‐friction properties at low speed and heavy load. This work can serve as a reference for the design of hydrophilic fiber reinforced polymer composites to reduce wear and improve lubrication performance.
Comparative LC–MS analysis of tropolone alkaloids from in vitro cultures and native sources of Gloriosa superba by Kendrick mass defect plots
Authors: Zarev Yancho , Popova Pavlinka , Foubert Kenn , Ionkova Iliana , Pieters Luc 
Published: September 2020

AbstractIntroductionGloriosa superba L. is a promising antitumoural plant species as a source of colchicinoids. Ethnobotanical applications of G. superba are associated with different plant parts such as leaves, seeds, fruits, tuber and the whole plant.ObjectivesA comparative phytochemical study of purified extracts from in vitro cultures and native tubers of G. superba was carried out by ultrahigh‐performance liquid chromatography‐high‐resolution mass spectrometry (UHPLC‐HR‐MS) in combination with the mass defect filtering (MDF) technique.Material and methodsThe individual compounds were tentatively annotated using database correlations, retention time (Rt), accurate m/z data obtained by electrospray ionisation (ESI) (+)‐HR‐MS, proposed elemental composition, ring double bond equivalent (RDBeq) values and HR‐MS/MS fragmentation patterns. Moreover, the identification was based on transforming the exact mass ratio (m/z) for the protonated molecular ions [М + Н]+ of the observed metabolites in Kendrick nominal masses (NKMs) and calculation of the Kendrick mass defect (KMD), which made it possible to graphically present the ion peaks in Kendrick plots.ResultsBuilding Kendrick plots allows easy differentiation of small structural differences such as methylation or demethylation of compounds from the same homologous series. In this way, a wide range of tropolone alkaloids was characterised. A greater variety was observed in in vitro cultures, compared to native sources.ConclusionThis LC–MS analysis unambiguously demonstrated the presence of tropolone alkaloids in in vitro cultures of G. superba. This approach of LC–MS data interpretation can be used to understand complex mass spectra such as those of plant extracts.
Effect of nanofillers characteristics and their selective localization on morphology development and rheological properties of melt‐processed polylactide/poly(butylene adipate‐co‐terephthalate) blend composites
Authors: Salehiyan Reza , Nofar Mohammadreza , Malkappa Kuruma , Ray Suprakas Sinha 
Published: September 2020

AbstractThis article reports the effects of the characteristics and selective localization of nanofillers on the morphology development and rheological properties of melt‐processed polylactide/poly(butylene adipate‐co‐terephthalate) (PLA/PBAT) blend composites. Four types of nanofillers (1 wt%) are used: nanoclay (Cloisite30B [C30B]), carbon nanotubes (CNTs), nanosilica, and graphene oxide (GO). Transmission electron microscopy studies reveal that C30B is localized mainly at the PLA/PBAT interface, whereas silica, GO, and CNT are localized in PBAT droplets, although some CNTs also appear toward the interface inside the PBAT. Despite their selective localization inside the PBAT, CNTs are found to be the most effective particles for droplet size reduction, whereas silica nanoparticles are ineffective. The CNT bundles recoil during melt blending, and eventually, their breakage facilitates droplet breakup. The effects of nanofiller localization and annealing under dynamic shear on the blend morphologies are also explored through rheological analysis. The results show an anomalous relationship with the morphologies of the composites. It is also found that both coalescence and thermal degradation are involved in the annealing process of the blends. Interestingly, the CNT‐filled composites may have been transformed into co‐continuous‐like structures during annealing, unlike the other blends studied here.
Injectable dextran‐fluorenylmethoxycarbonyl phenylalanine composite hydrogels with improved mechanical properties
Authors: Abraham Jancy N , Joseph Seena , Trivedi Rishabh , Karle Mrunal 
Published: September 2020

AbstractLow molecular weight hydrogels are recently gaining importance owing to their applications in material sciences and biology. A new class of composite hydrogel was developed using polysaccharides such as dextran and fluorenylmethoxycarbonyl phenylalanine (FmocF) in a phosphate buffer. The molecular weight and concentration of the dextran were varied to obtain rigid but injectable hydrogels without using other crosslinking agents. From the different molecular weights of dextran studied (5k, 40k and 70k), a combination of FmocF (0.6% w/v) and dextran 40k (0.012% w/v) composite gels yielded a maximum value of storage modulus of approximately 1500 Pa, which is 3.5 times higher than the storage modulus of pure FmocF gels. Scanning electron microscopy of FmocF/dextran composite gels revealed highly tangled fibrous structures with dense branches and lower fiber diameter compared to pure FmocF gels. The high‐intensity hydrogen‐bonded N–H peak in the infrared spectra showed enhanced hydrogen bonding in FmocF/dextran composite gels compared to pure FmocF gels. The dextran acts as an impurity in the process of fibrillation, leading to a crystallographic mismatch, and densely packed thin fibers are formed. These gels exhibited gel to sol and sol to gel conversion with temperature or external stress and showed injectable behavior. © 2020 Society of Industrial Chemistry
Characteristics of Non‐Spine Musculoskeletal Ambulatory Care Visits in the United States, 2009‐2016
Authors: Song Amos , Kim Peter , Ayers Gregory , Jain Nitin 
Published: September 2020

BackgroundDespite the enormous economic and societal impact of musculoskeletal disorders, detailed data on the patient demographics and visit characteristics of nonspine musculoskeletal ambulatory care are sparse. Such data are essential to inform policymakers on population health needs and to justify health care resource allocation.ObjectiveTo determine the demographic, patient, and visit characteristics of adult musculoskeletal ambulatory clinic visits, with the exception of spine visits, in the United States.DesignSurvey/registry.SettingNational Ambulatory Medical Care Survey (NAMCS), Centers for Disease Control and Prevention (CDC) 2009 to 2016.PatientsThe NAMCS was designed to capture information regarding the provision and use of ambulatory medical care services in the United States. Nonfederally employed office‐based physicians reported data for this survey from 2009 to 2016.InterventionsNone.Main Outcome Measure(s)Average annual estimated number (in 100 000s), Average annual estimated rate of ambulatory care musculoskeletal visits per 100 U.S. adults.ResultsDuring 2009 to 2016, the leading cause of musculoskeletal visits was knee symptoms (15.3 million annually from 2009 to 2010, 14.0 million annually from 2011 to 2012, 12.5 million annually from 2013 to 2014, and 12.4 million annually from 2015 to 2016). Musculoskeletal visits were most frequent in patients that were 45 to 64 years of age (40.4% to 43.6% of visits were for patients 45 to 64 years of age depending on body region). Orthopedic surgeons conducted more musculoskeletal visits than any other physician specialty for all body regions. Among body regions, magnetic resonance imaging (MRI) studies were ordered most commonly for patients with shoulder (total visits in 100 000 ± standard error [SE] 47.00 ± 0.21; 12.5% of total visits for shoulders) and knee symptoms (61.85 ± 0.15; 11.4% of total visits for knees). Opioid and opioid analgesic combinations (9.2% to 14.8% of visits) were most commonly prescribed in visits related to hip complaints.ConclusionsVisits were most frequent for knee symptoms and in patients of working age groups, which likely affects work productivity. Orthopedic surgeons were the most common provider specialty. Opioid medications were prescribed most commonly for patients with hip symptoms, which may highlight an area for potential intervention given the ongoing opioid crisis.
Theoretical research on the direct carboxylation of benzene with CO2 catalyzed by different carbene‐CuOH compounds
Authors: Liu Cong 
Published: September 2020

AbstractThe direct carboxylation between the benzene C–H and CO2 is a long‐standing challenge in catalysis. Based on the known experimental process for the direct carboxylation of fluorobenzene, herein, a theoretical design of efficient carbene‐copper catalysts for the direct carboxylation of benzene was reported. It was found that the reaction included two steps: C–H bond breaking and CO2 insertion into Cu‐phenyl. C–H breaking is the rate‐determining step. To find out a more effective catalyst, totally, 16 carbene‐copper compounds with different electronic and steric structures were investigated. The energy barriers for the C–H bond breaking range from 104.2 to 153.7 kJ/mol. Two effective methods are proposed for improving the catalytic reactivity: reducing the electronically active substituent on carbene and introducing interaction to stabilize the transition state (TS). Based on these findings, adopting a well‐known (amino)(silyl)carbene modified by a –NH2 group gives the most effective catalyst for the direct carboxylation of benzene. Using –NH2 group can introduce two strong interactions (OOH···HNH2 and NNH2···Cu) during the formation of TS, which can greatly stabilize the structure of TS and dramatically reduce the energy barrier. The catalytic reactivity of the most effective carbene‐copper catalyst is comparable with the noble metal‐based ruthenium pincer carboxylate complexes.
Retention of poly(N‐isopropylacrylamide) thin films on polycarbonate via polymer interdiffusion
Authors: Zhang Newby Bi‐min , Malekzadeh Elham , Alghunaim Abdullah 
Published: September 2020

AbstractThis study explored the possibility of polymer interdiffusion for retaining thermoresponsive poly(N‐isopropylacrylamide) (pNIPAAm) on polycarbonate (PC). It was hypothesized that interdiffusion could be facilitated either by increasing the annealing temperature or by treating PC using air plasma (AP) and ultra‐violet ozone (UVO). The results showed that increasing annealing temperature only moderately improved pNIPAAm retention. Treating PC with AP led to an increase in surface‐active groups and a greatly enhanced retention of pNIPAAm. UVO treatment, however, severely damaged the PC layer with no noticeable enhancement on pNIPAAm retention. The retained pNIPAAm films on PC exhibited thermoresponsive behavior as evidenced by water contact angle and desired cell attachment/detachment behaviors. These results illustrate the simplicity of using polymer interdiffusion to successfully retain pNIPAAm films on a polymer, and the resulting substrates would be less expensive and more versatile than those retained on brittle supports (e.g., glass) for applications that require resilient thermoresponsive substrates.
Polysomnographic characteristics and sleep‐disordered breathing in Schaaf‐Yang syndrome
Authors: Powell Weston T. , Schaaf Christian P. , Rech Megan E. , Wrede Joanna 
Published: September 2020

AbstractIntroductionSchaaf‐Yang syndrome (SYS) is a genetic disorder caused by truncating variants in the MAGEL2 gene located in the maternally imprinted Prader‐Willi syndrome (PWS) region at 15q11‐13. The SYS phenotype shares features with PWS, a syndrome with known high incidence of sleep disorders. However, the spectrum of sleep‐disorders in SYS has not been described.MethodsWe performed a retrospective analysis of polysomnograms from 22 patients in an international SYS cohort. Sleep characteristics for individuals with the common c.1996dupC variant (n = 10) were compared to other truncating variants (n = 11).ResultsWe collected 33 sleep study reports from 22 patients, ages 2 months – 18.5 years (mean 6.5 years). Mean sleep efficiency was 70.5% (range 45%–93%) with arousal index 14.1/h (1.2–45/h). The mean apnea‐hypopnea index (AHI) was 19.1/h (0.9–49/h) with mean obstructive AHI (oAHI) of 16.3/h (0.6–49/h). Mean central apnea index was 2.8/h (0–14/h). Mean oxygen desaturation index was 20.8/h (range 0–85/hr). Obstructive sleep apnea (OSA) was diagnosed in 81%, and 62% had moderate or severe OSA. Elevated central apnea index occurred in 9.5%. Comparison by genotype groups and age did not reveal any difference in OSA findings. Periodic limb movement index (PLMI) was elevated in 4/15 (26%).ConclusionOSA is frequently identified on polysomnography in patients with SYS. The mean PLMI is elevated compared to normative data. Patients with SYS should have routine polysomnography screening due to high risk of sleep disorders.
On the 13C‐NMR chemical shift anisotropy patterns and aromatic character in strained fullerenes: Computational analysis of D6h/D2d‐C36 fullerene
Authors: Guajardo‐Maturana Raul , Rodríguez‐Kessler Peter L. , MacLeod‐Carey Desmond , Muñoz‐Castro Alvaro 
Published: September 2020

AbstractThe NMR characterization of small C36 hollow fullerene exposes a stable cage with structural features based on its strained curved π‐surface in a D6h‐symmetry. Our results indicate that planar‐like aromatic properties of the D6h‐C36 isomer decrease to a nonaromatic cage for D2d‐C36 after Stone‐Wales transformation of an equatorial [6.6] bond. This is given by the decrease of conjugation in the strained π‐surface after Stone‐Wales transformation. Calculated nuclear shielding shows that the main shielding component is always oriented perpendicularly to the cage π‐surface despite the larger curvature degree, as a result of the sp2 character of carbon atoms, resembling C60. Moreover, the D6h‐ and D2d‐C36 cages differ in their charge distribution properties, leading to charge accumulation in the strained cap of the former that leads to a polymerization‐prone cage, which contrasts with that expected for the D2d structure. Hence, structural rearrangements of these non‐Hirsch aromatic fullerenes show that their inherent global behavior requires considering the structural features besides electron counting rules.
Benchmark studies of hydrogen bond governing reactivity of cephalosporins inL1metallo‐β‐lactamase: Efficient and reliableQSPRequations
Authors: Khrenova Maria G. , Levina Elena O. , Tsirelson Vladimir G. 
Published: September 2020

AbstractThe combined quantum mechanics/molecular mechanics (QM/MM) simulations of equilibrium geometry configurations followed by electron density analysis provide reliable quantitative structure‐property relationship equations to estimate the reactivity of compounds in the active sites of enzymes. The main drawback is high computational cost of such calculations. Here, we report on a benchmark study aiming to optimize computational protocol for the accuracy of predictions. We considered an important example of cephalosporin hydrolysis in the active site of L1 metallo‐β‐lactamase and found that it is important to consider contributions to the one‐electron part of the QM Hamiltonian from all MM system rather than using the cutoff of electrostatic interactions. Switching from the reference PBE0‐D3/6‐31G(d,p) QM protocol to the reduced PBE0‐D3/6‐31G scheme decreases the number of basis set functions by almost twice, increasing the error of the rate constant estimates up to 18 seconds−1compared with the reference 10 seconds−1. Therefore, the QM(PBE0‐D3/6‐31G)/MM(AMBER) level of theory can be recommended for estimates of cephalosporin reactivity in the search of new antibiotics.
Indirect adaptive model predictive control and its application to uncertain linear systems
Authors: Di Cairano Stefano , Danielson Claus 
Published: September 2020

SummaryWe consider constrained systems that are represented by uncertain models with unknown constant or slowly varying parameters. We propose an indirect adaptive model predictive control (IAMPC) approach where the prediction model can be adjusted during controller operation by a separately designed estimator that satisfies only a minimal set of assumptions. The controller guarantees constraint satisfaction despite the uncertainty in the parameters by means of a robust control invariant set, and input‐to‐state stability with respect to the estimation error by means of an appropriately designed method for adjusting the IAMPC prediction model and cost function based on the evolution of the parameter estimate. The controller has minimal computational overhead with respect to a nominal MPC and for the special case of uncertain linear systems, we obtain a constructive design procedure for the IAMPC which only solves quadratic programs during closed‐loop control.
Robust global stabilization of a class of underactuated mechanical systems of two degrees of freedom
Authors: Gutiérrez‐Oribio Diego , Mercado‐Uribe José A. , Moreno Jaime A. , Fridman Leonid 
Published: September 2020

SummaryIn this article, the global stabilization of a class of underactuated mechanical systems of two degrees of freedom (DoF) is addressed, despite the presence of Lipschitz disturbances and/or uncertainties and uncertain control coefficient in the model. Using two second‐order continuous sliding modes algorithms, the control task is performed, reaching finite‐time convergence in one part of the dynamics and generating a continuous control signal. The efficacy of the proposed controllers is illustrated via simulations for the reaction wheel pendulum (RWP) and the translational oscillator with rotational actuator (TORA) systems, and by means of experiments on the RWP system, comparing the presented algorithms with a linearizing controller.
It’s Time to Be Scientific About Dyslexia
Authors: Elliott Julian G. 
Published: September 2020

AbstractTha author argues that despite the vast proliferation of scientific research, our understanding of dyslexia is marked by serious weaknesses of conceptualization, definition, and operationalization that are not only unscientific but also result in impoverished practice in schools, social inequity in both understanding and provision for many struggling readers, and ultimately, reduced life chances for millions of students worldwide. Key to this problem is the inconsistency of the use of the term dyslexia in both scientific research and clinical and educational practice. Four different, common conceptions of dyslexia are outlined, and the implications that each of these have for work with struggling readers are discussed. Whereas it is often claimed that scientific understandings, derived from genetics, neuroscience, and cognitive science, enable clinicians to validly identify, from within a larger group of poor readers, those individuals with dyslexia, the author shows this to be not only misleading but also potentially deleterious to broader inclusive practice. The author argues that the seemingly scientifically based construction of the dyslexic individual, often buoyed by vested interests, typically favors more socially privileged students and often undermines attempts to identify and help all of those who struggle to learn to read. Common responses by proponents to challenges to the dyslexia construct are outlined and discussed. In conclusion, the author argues that scientists, researchers, clinicians, and educators have a responsibility to address and confront the real‐world consequences of much science but little wisdom in the field of reading disability.
Beyond Decoding: A Meta‐Analysis of the Effects of Language Comprehension Interventions on K–5 Students’ Language and Literacy Outcomes
Authors: Silverman Rebecca D. , Johnson Erika , Keane Kristin , Khanna Saurabh 
Published: September 2020

ABSTRACTThe debate over the science of reading has focused primarily on decoding (i.e., connecting letters and sounds to read words) and whether to use phonics to teach it. However, research on reading has included much more than decoding. Language comprehension, which allows readers to derive meaning from text, is an equally critical component of reading. Research has suggested that explicit instruction on the components of language comprehension—vocabulary and semantics, morphology, and syntax—can support language and reading comprehension. To inform the field on the science of reading as it pertains to language comprehension, in this meta‐analysis of recent language comprehension interventions (n = 43) in U.S. elementary schools, the authors examined whether effects vary depending on participant and intervention characteristics. Findings suggest positive effects on custom measures of vocabulary, listening comprehension, and reading comprehension but not on standardized measures of these outcomes. Results also indicate positive effects for English learners and promise for multicomponent interventions and those that include technology. Much more research is needed on how best to support language comprehension for underserved populations (e.g., students from low‐income backgrounds) and how interventions can be optimized to support generalizable language and literacy outcomes. Implications for policy and practice are discussed.
Peridynamic modeling of prefabricated beams post‐cast with steelfiber reinforced high‐strength concrete
Authors: Xu Chen , Yuan Yong , Zhang Yiming , Xue Yuan 
Published: September 2020

AbstractFor connecting precast concrete members in prefabricated structures, steel fiber reinforced high‐strength concrete (HSFRC) shows greater bearing capacity and better durability than normal reinforced concrete. When these structures are continuously loaded, multiply micro and macro cracks will appear. The modeling of this process is challenging because the conventional finite element modeling commonly encounters numerical problems such as stress locking and overestimations of the damaging zones. On the other hand, the novel peridynamics‐based theory models the continuous and discontinuous processes in the same framework, showing robustness. In this work, based on the recently presented micropolar peridynamics with shear deformability, a numerical tool with implicit iteration scheme for quasi‐static loading condition is built. With the proposed numerical tool, the damage processes of prefabricated beam post‐cast with HSFRC are simulated. The interaction between precast, post‐cast concrete, and rebars are taken into consideration. For validations, the numerically obtained results are compared with the experimental results, indicating that this tool can provide agreeable crack patterns, initial cracking loads, and yield loads of the beams.