Miracle-dz/UniFAR-FTUs huggingface dataset:
Rapid kinetic evaluation of homogeneous single-site metallocene catalysts and cyclic diene: how do the catalytic activity, molecular weight, and diene incorporation rate of olefins affect each other?

The kinetics and mechanism of ethylene and cyclic diene 5-ethylidene-2-norbornene (ENB) copolymerization catalyzed by rac-Et(Ind)2ZrCl2/[Ph3C][B(C6F5)4]/triisobutylaluminium (TIBA) were investigated using a quench-labeling procedure using 2-thiophenecarbonyl chloride (TPCC). The E/ENB copolymers were characterized by gel permeation chromatography (GPC), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and 1H nuclear magnetic resonance (NMR) spectroscopy and sulfur analysis. To reduce the errors of the ethylene–diene copolymerization for the kinetics study, we selected E/ENB with steric and electronic features that permit us to elucidate the metallocene catalyst behavior against dienes. A quantitative approach of catalyst speciation, stereodynamics, and micro-kinetics assisted the resolution of mechanistic problems, such as the elastomeric synthesis of ethylene propylene diene monomer rubber (EPDM), the catalyst resting state nature, and how much ion-pairing occurs during polymerization. We report here the precise observation of metal–polymer species, explanation of the dynamics of their initiation, propagation, and termination, and ethylene ENB copolymer development. An approach based on acyl chloride was used to selectively quenched transition metal–polymer bonds to evaluate the polymeric catalyst in terms of its reaction rate, Rp, propagation rate content, kp, and mole fraction of active centers. It is noted that the decline in catalytic activity in the range of 1800 s, and the active center [Zr]/[*C] fraction significantly increased during the initial 1000 s and then tended towards a steady figure of 86%. It is suggested that nearly complete initiation of all olefins catalysts can be obtained after a sufficiently extended reaction. The quick increase in active sites in the first stage can be described by the immediate initiation of active sites positioned on the surfaces of catalyst particles. The initial polymerization rate, Rp, is high and the crystalline properties of the E/ENB copolymer are low due to the greater incorporation of ENB in the polymer backbone, and later the polymerization reaction rates remained stable with a lower mol% of ENB. The melting temperature (Tm) ranges from 108 to 127 °C, whereas the crystalline temperature ranges from 63 to 108 (J g−1). In the E–ENB copolymers, the value of kpE is much greater than that of kpENB; at 120 s, the kpE and kpENB values are 9115 and 431 L mol−1 s−1, respectively, implying smaller diffusion barriers in the early stages, which are close to the actual propagation rate constant.
Dispersion of thiol capped AuNPs in rufigallol derivative discotic liquid crystal-Enhanced one dimensional electrical conductivity

ABSTRACT Rufigallol is one of the earliest systems reported to form discotic columnar mesophase at room temperature. In the present study, we have studied the impact of surface-functionalised gold nanoparticles (AuNPs) on the impedance response of a rufigallol derivative discotic liquid crystal in the frequency range of 1 Hz–40 MHz. The experimental results show that nanoparticle doping marginally alters the permittivity of the discotic host and significantly increases its conductivity. A Debye-type relaxation process in the low MHz regime originates due to the hopping of mobile charge carriers and the alignment of dispersed AuNPs in the host matrix. The dispersed systems are also characterised using techniques, viz. Differential Scanning Calorimetry (DSC), Polarised Light Microscopy (PLM), Ultraviolet-visible (UV–Vis) spectroscopy and Small Angle X-ray Scattering (SAXS). Both dielectric and texture studies confirm the formation of a well-ordered columnar structure of the discotic phase at room temperature. These results are supported by SAXS studies as well, which suggest an increase in π- π orbital overlapping in dispersed samples. The study also illustrates the variation of different hexagonal lattice reflection planes with respect to the decrease in temperature.
A numerical solution to fluid-structure interaction of membrane structures under wind action

A numerical simultaneous solution involving a linear elastic model was applied to study the fluid-structure interaction (FSI) of membrane structures under wind actions, i.e., formulating the fluid-structure system with a single equation system and solving it simultaneously. The linear elastic model was applied to managing the data transfer at the fluid and structure interface. The monolithic equation of the FSI system was formulated by means of variational forms of equations for the fluid, structure and linear elastic model, and was solved by the Newton-Raphson method. Computation procedures of the proposed simultaneous solution are presented. It was applied to computation of flow around an elastic cylinder and a typical FSI problem to verify the validity and accuracy of the method. Then fluid-structure interaction analyses of a saddle membrane structure under wind actions for three typical cases were performed with the method. Wind pressure, wind-induced responses, displacement power spectra, aerodynamic damping and added mass of the membrane structure were computed and analyzed.
Impact of perinatal factors on biomarkers of cardiovascular disease risk in preadolescent children

Background: This review aims to summarize associations of the perinatal environment with arterial biophysical properties in childhood, to elucidate possible perinatal origins of adult cardiovascular disease (CVD). Methods: A systematic search of PubMed database was performed (December 2020). Studies exploring associations of perinatal factors with arterial biophysical properties in children 12 years old or less were included. Properties studied included: pulse wave velocity; arterial stiffness or distensibility; augmentation index; intima–media thickness of aorta (aIMT) or carotids; endothelial function (laser flow Doppler, flow-mediated dilatation). Two reviewers independently performed study selection and data extraction. Results: Fifty-two of 1084 identified records were included. Eleven studies explored associations with prematurity, 14 explored maternal factors during pregnancy, and 27 explored effects of low birth weight, small-for-gestational age and foetal growth restriction (LBW/SGA/FGR). aIMT was consistently higher in offspring affected by LBW/SGA/FGR in all six studies examining this variable. The cause of inconclusive or conflicting associations found with other arterial biophysical properties and perinatal factors may be multifactorial: in particular, measurements and analyses of related properties differed in technique, equipment, anatomical location, and covariates used. Conclusion: aIMT was consistently higher in LBW/SGA/FGR offspring, which may relate to increased long-term CVD risk. Larger and longer term cohort studies may help to elucidate clinical significance, particularly in relation to established CVD risk factors. Experimental studies may help to understand whether lifestyle or medical interventions can reverse perinatal changes aIMT. The field could be advanced by validation and standardization of techniques assessing arterial structure and function in children.
A Novel Sparse Polynomial Expansion Method for Interval and Random Response Analysis of Uncertain Vibro-Acoustic System

For the vibro-acoustic system with interval and random uncertainties, polynomial chaos expansions have received broad and persistent attention. Nevertheless, the cost of the computation process increases sharply with the increasing number of uncertain parameters. This study presents a novel interval and random polynomial expansion method, called Sparse Grids’ Sequential Sampling-based Interval and Random Arbitrary Polynomial Chaos (SGS-IRAPC) method, to obtain the response of a vibro-acoustic system with interval and random uncertainties. The proposed SGS-IRAPC retains the accuracy and the simplicity of the traditional arbitrary polynomial chaos method, while avoiding its inefficiency. In the SGS-IRAPC, the response is approximated by the moment-based arbitrary polynomial chaos expansion and the expansion coefficient is determined by the least squares approximation method. A new sparse sampling scheme combined the sparse grids’ scheme with the sequential sampling scheme which is employed to generate the sampling points used to calculate the expansion coefficient to decrease the computational cost. The efficiency of the proposed surrogate method is demonstrated using a typical mathematical problem and an engineering application.
Modelling impacts of high-speed rail on urban interaction with social media in China’s mainland

ABSTRACT High-Speed Rail (HSR) has increasingly become an important mode of inter-city transportation between large cities. Inter-city interaction facilitated by HSR tends to play a more prominent role in promoting urban and regional economic integration and development. Quantifying the impact of HSR’s interaction on cities and people is therefore crucial for long-term urban and regional development planning and policy making. We develop an evaluation framework using toponym information from social media as a proxy to estimate the dynamics of such impact. This paper adopts two types of spatial information: toponyms from social media posts, and the geographical location information embedded in social media posts. The framework highlights the asymmetric nature of social interaction among cities, and proposes a series of metrics to quantify such impact from multiple perspectives – including interaction strength, spatial decay, and channel effect. The results show that HSRs not only greatly expand the uneven distribution of inter-city connections, but also significantly reshape the interactions that occur along HSR routes through the channel effect.
Compact and High Gain 4 × 4 Circularly Polarized Microstrip Patch Antenna Array for Next Generation Small Satellite

In this article, a high gain and compact 4 × 4 circularly polarized microstrip patch antenna array is reported for the data transmission of the next-generation small satellite. The radiating element of the circularly polarized antenna array is realized by the conventional model of the patch with truncated corners. A compact two-stage sequential rotational phase feeding is adopted that broadens the operating bandwidth of the 4 × 4 array. A small stub is embedded in the sequential rotational feed, which results in better performance in terms of the S-parameters and sequential phases at the output ports than sequential rotational feed without open stub. A prototype of the array is fabricated and measured. Fulfilling the application requirements of the next-generation small satellites, the array has the left-handed circularly polarized gain of more than 12 dBic with the axial ratio level below 1.5 dB in the ±10∘ angular space with respect to the broadside direction for the whole bandwidth from 8.05 GHz to 8.25 GHz. Moreover, the left-handed circularly polarized gain varies from 15 to 15.5 dBic in the desired band. The radiation patterns are measured; both the co- and X-pol are validated.
Numerical modelling of free‐surface flows in ship hydrodynamics

Current trends in the investigation of ship hydrodynamics are reviewed with emphasis on the problem of wave‐body interaction. This includes the classical seakeeping problem and as a special case, the problem of prediction for the drag encountered by a ship advancing in calm water. Specific issues related to the numerical treatment of the air–water interface are examined, with emphasis on the modelling of wave breaking. The discussion on the large‐scale modelling of the flow around ships is focused on the prediction of wave loads, ship motions and resistance in calm water. Copyright © 2003 John Wiley & Sons, Ltd.
Prediction of Europium Retention in Perovskite: Potential Candidates for an Engineering Barrier in the Disposal of Radioactive Waste

Perovskites, such as tausonite, are crystalline metal oxides with excellent optical and photocatalytic properties and have also been used successfully in the retention of metals, simulating the isotopes of uranium and plutonium. In this work, different pseudo-order and thermodynamic models were studied to achieve the prediction of the sorption of Eu3+ (chemical analogous for actinides) in tausonite. The effects of gamma irradiation and temperature on the structural characteristics of the material were determined, as an additional step in the evaluation of material as an engineering barrier in the disposal of radioactive waste. The results obtained show that the tausonite is resistant to the gamma irradiation and thermal energy. Likewise, it was possible to determine that europium sorption occurs through an exothermic and spontaneous reaction, as well as through the formation of surface complexes, where Eu3+ ions bind to sites on the tausonite by dipole-dipole interaction. Furthermore, it was shown that the sorption mechanism is influenced by diffusive phenomena, which participate in the formation of surface complexes. Additionally, a new sorption model with respect to pH was proposed, which allowed determining the physical parameter π. The evidence obtained suggests that π is a physical parameter that relates pH to an optimal value and could explain the equilibrium between the surface complexes that tausonite forms with europium. Likewise, the evidence suggests that 50 kg of tausonite would have the capacity to retain at least 26.59 g of alpha-emitting radionuclides, equivalent to a waste package (900 kg) with a maximum activity of 4000 Bq/g.
Relative Differences in Na+/K+-ATPase Activity between Mountain and Coastal Populations of the Japanese Frog, Buergeria japonica

Abstract. Buergeria japonica (Rhacophoridae) thrives in diverse habitats, from montane forests to the mouths of small rivers opening onto sandy beaches. The osmoregulatory system of B. japonica may differ between populations living in these contrasting environments. In this study, we compared the activity of cutaneous Na+/K+-ATPase in two populations of B. japonica from different habitats (montane vs. coastal). Our results reveal a significant difference between the Na+/K+-ATPase activity of the two populations of B. japonica, with the coastal population having higher Na+/K+-ATPase activity. Because the Na+/K+-ATPase plays a crucial role in osmoregulation in high salinity, these results are consistent with the higher salinity tolerance of the coastal population. It is not known whether the difference in Na+/K+-ATPase activity between populations is a result of local adaptation or phenotypic plasticity. More detailed work will be needed to disentangle the patterns of differentiation in physiological responses to salt in these amphibians.
Prevalence and factors associated with the need for removable prostheses in brazilian elderly

Objective: This study aimed to identify the prevalence and factors associated with the need for removable prostheses in the elderly Brazilian population. In addition, its impact on eating difficulties and self-perceived oral health was determined. Methodology: This cross-sectional, population-based study used data from the last National Health Survey (NHS) carried out in Brazil. Chi-square test was used to initially analyze the data, followed by multiple Poisson regression to obtain adjusted prevalence ratios. Results: A total of 11,697 elderly people were included, of whom 90.8% needed removable prostheses. Complete dentures were needed in 40.9% of participants, while partial dentures were needed by 49.9%. The elderly who were older (p=0.001), had grayish-brown complexion (p=0.004), a low level of education (p<0.001), and multiple chronic diseases (p<0.001) had a greater need for removable prostheses. Successively, this need had an impact on poor self-perceived oral health (p<0.001) and greater difficulties in eating (p<0.001). Conclusion: The need for a removable prosthesis is associated with worse socioeconomic and health conditions. In addition, it has a negative impact on self-perceived oral health and feeding.
Experimental Study of a Self-Centering Beam–Column Connection with Bottom Flange Friction Device

A new beam-to-column connection for earthquake-resistant moment-resisting frames is introduced. The connection has a beam bottom flange friction device (BFFD) and posttensioned (PT) high-strength steel strands running parallel to the beam. The BFFD provides energy dissipation to the connection and avoids interference with the floor slab. The PT strands produce self-centering connection behavior. The connection behavior requires minimal inelastic deformation of the connection components and the beams and columns, and requires no field welding. A series of seven large-scale tests were performed to investigate the effect of the BFFD friction force, connection details, and the loading history on the performance of the connection under cyclic loading. The test results indicate that the BFFD provides reliable energy dissipation, and that the connection remains damage-free under the design earthquake.
Experimental investigation on the effect of multiple injection strategies on emissions, noise and brake specific fuel consumption of an automotive direct injection common-rail diesel engine

Abstract High-pressure common-rail injection systems nowadays allow a very high degree of flexibility in the timing and quantity control of multiple injections, which can be used to obtain significant reductions in engine noise and emissions. The aim of this study is to develop a better understanding of the relationship between injection strategies and the combustion and emission formation process. Some multiple injection strategies (pilot-pilot-main and pilot-main-after) have therefore been analysed to highlight their influence on the soot, NOx combustion noise and b.s.f.c. (brake specific fuel consumption) of a passenger car direct injection diesel engine prototype. Finally, the main combustion characteristics were determined, for each operating condition, on the basis of a heat release analysis and a correlation was attempted between the combustion parameters and emissions, noise and b.s.f.c.
SOIL WEED SEED BANK STATUS IN THE AGROECOLOGICAL CONDITIONS OF CHITRAL, PAKISTAN

A greenhouse experiment was carried out at the Agricultural Research Station (ARS), Shen Lasht, Chitral during 2016-17. There were five different locations in district Chitral from where the soil samples were collected which included Drosh, Shen Lasht, Garam Chashma, Ayun and BoonyLasht. A total of 300 samples were collected from all locations with 60 samples from each location. The 300 soil samples collected were placed in trays of medium sizes i.e. 27 cm x 21 cm x 4 cm = 2268 cm3. The trays were arranged in three repetitions having 100 samples in each repetition. Each repetition of 100 samples contained samples from 5 locations, in each location 4 sites (east, west, north and south each at 100 m distance from each other) and at each site samples were collected from 5 different depths, making a total of 100 samples in one repetition i.e. 5 x 4 x 5 = 100 and with repetitions making a total of 300 samples in one district. The results indicated that in the soil samples of district Chitral a total of 31 noxious weeds were recorded. Out of the 31 different weeds, 23 were broad leaves, eight were grasses and one was sedge. In another angle, 24 weeds were annuals while the rest were perennials out of the 31 weeds identified. A total of 17 different plant families were represented by the weeds recorded in the soil samples of Chitral region. Among the different locations of Chitral, the highest weed seed bank was recorded in the soil samples of ARS Shen Lasht area. Weed seed banks have always been higher in areas with mild winters, where the Shen lasht area is having milder winters as compared to the other areas in Chitral. The lowest seed bank was recorded in the soil samples of Garam Chashma, which was however statistically at par with the rest of the locations studied in Chitral. As far as the seed banks in the depths are concerned, largest weed seed bank was observed in the depth of 6 to 12 cm. The smallest seed bank was at the depth of 30 cm followed by the depth of 24 and 18 cm. Therefore, it is evident that the major weed seed bank lies in the upper 6-12 cm depth of the soil. In case of the interaction, the largest weed seed bank was recorded at ARS Sheen lasht at the depth of upper 6 cm of the soil profile whereas the weed seed bank was very low below the 12cm depth of soil upto 30 cm in the Garam Chashma area of Chitral. Out of the total 31 weeds recorded in soil samples of Chitral, the top 10 weeds in terms of the relative weed densities, relative weed frequencies and importance value indices were Convolvulus arvensis, Rumex crispus, Poa annua, Galium aparine, Avenafatua, Trianthemaportulacastrum, Silybum marianum, Sorghumhalepense, Euphorbia helioscopia, and Loliumtenulentumspecies. The IVI values for these weeds were 14.01, 13.96, 13.07, 11.83, 11.57, 11.12, 10.35, 10.09, 10.02, and 9.99, respectively. Moreover, these IVIs indicate that out of the topmost 10 problematic weeds eight weeds are broad leaved and two are grassy weeds.
The effects of foreign language programmes in early childhood education and care: a systematic review

ABSTRACT This systematic review investigates the effects of foreign language programmes in early childhood education and care (ECEC), which are increasingly popular. Foreign language ECEC centres familiarise very young children with a foreign language, and in general also expose them to the majority language. This review synthesises research on the effects of foreign language ECEC on children’s development of the foreign language, majority language, first language, and wellbeing, as well as programme-related and child-related factors that influence language development and wellbeing. The reviewed studies indicate that foreign language ECEC fosters foreign language development, without negatively impacting the majority and first language. Children can experience positive wellbeing in these programmes, but only if programmes are play-based and if the language policy is not too strict. Some studies report that programme characteristics, such as input quantity, language policy, and teacher strategies, modulate the effects of foreign language ECEC on language development and wellbeing. Few of the reviewed studies examined child characteristics, but the available findings indicate that children’s age, as well as their temperament and in-class behaviour, are related to foreign language learning. However, these findings need to be interpreted with caution, because research into foreign language ECEC is still in its infancy.