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This study aimed to determine whether increased carotenoids intake was associated with reduced risk of gestational diabetes mellitus (GDM). We performed a cross-sectional analysis using data from Tongji Maternal and Child Health Cohort study. The dietary carotenoids intake of 1978 pregnant women was assessed using a researcher-administered FFQ before undertaking an oral glucose tolerance test at 24–28 weeks. Multivariate logistic and linear regression analyses were used to obtain the effect estimates. Participants in the highest quartile of lycopene intake showed a lower risk of GDM (OR 0·50; 95 % CI 0·29, 0·86; Pfor trend = 0·007) compared with those in the lowest quartile; each 1 mg increase in lycopene consumption was associated with a 5 % (95 % CI 0·91, 0·99; Pfor trend = 0·020) decrease in GDM risk. No significant association was found between α-carotene, β-carotene, β-cryptoxanthin, lutein/zeaxanthin intake and GDM risk. Multiple linear regression analysis suggested an inverse association between lycopene intake and fasting blood glucose (FBG) (Pfor trend < 0·001); each 1 mg increase in lycopene intake was associated with 0·005 (95 % CI 0·002, 0·007; Pfor trend < 0·001) mmol/l decrease in FBG. Interaction analysis indicated consistent effect on each age or pre-BMI subgroup; however, a stronger protective effect of lycopene intake against GDM was observed among primigravid women (OR 0·20; 95 % CI 0·07, 0·55 in the highest v. the lowest quartile of intake; Pfor interaction = 0·036). In conclusion, dietary lycopene intake was mainly assumed via reducing FBG to decrease GDM risk, and the protection was relatively increased among primigravid women.
Chickenpox is a common acute and highly contagious disease in childhood; moreover, there is currently no targeted treatment. Carrying out an early warning on chickenpox plays an important role in taking targeted measures in advance as well as preventing the outbreak of the disease. In recent years, the infectious disease dynamic model has been widely used in the research of various infectious diseases. The logistic differential equation model can well demonstrate the epidemic characteristics of epidemic outbreaks, gives the point at which the early epidemic rate changes from slow to fast. Therefore, our study aims to use the logistic differential equation model to explore the epidemic characteristics and early-warning time of varicella. Meanwhile, the data of varicella cases were collected from first week of 2008 to 52nd week of 2017 in Changsha. Finally, our study found that the logistic model can be well fitted with varicella data, besides the model illustrated that there are two peaks of varicella at each year in Changsha City. One is the peak in summer–autumn corresponding to the 8th–38th week; the other is in winter–spring corresponding to the time from the 38th to the seventh week next year. The ‘epidemic acceleration week’ average value of summer–autumn and winter–spring are about the 16th week (ranging from the 15th to 17th week) and 45th week (ranging from the 44th to 47th week), respectively. What is more, taking warning measures during the acceleration week, the preventive effect will be delayed; thus, we recommend intervene during recommended warning weeks which are the 15th and 44th weeks instead.
We designed a resorcinol-formaldehyde (RF) sol–gel ink for direct ink writing of the microlattices. To improve the formability, the fresh microlattices were strengthened by surface catalysis with HCl atmosphere. After supercritical drying and carbonization, the sample’s specific surface area was 631 m2/g and the average pore size was 3.81 nm. Both RF aerogel and carbonized RF aerogel samples had millimeter-scale pore, micron-scale pore, and nanoscale skeleton. The pore and skeleton could provide high surface area and diffusion channels, which were beneficial to the adsorption performances. The carbonized RF aerogel sample fully adsorbed Dulbecco’s modified eagle medium in 250 min, which exhibited a good capacity of quick adsorption and indicated the potential application for cell supports.
With the rapid development of electronic information and technology, especially the explosive advance of novel electronic devices, ultra-wideband radar detector and satellite communication, the elimination of adverse electromagnetic waves (EWs) effectively is very necessary both for electronic safety and national defense security. As one of the important material basis for controlling adverse EW pollution, compatibility, shielding, and stealth capability of weaponry, microwave absorbing materials has long been an area of intense research activity. Graphene-based materials have attracted great interests for microwave absorption in recent years due to the unique structure and physicochemical properties of graphene, such as high specific surface area, ultrathin thickness, large interface, optical transmittance, and tunable conductive properties, etc. In this paper, the properties and absorption behavior of different kinds of microwave absorbing materials based on graphene were reviewed and discussed in detail. In addition, the perspective of the current challenges and key issues for achieving better microwave absorption performance of the graphene-based materials are provided.
Gamma prime (γ′) stability and its influence on tensile behavior of a newly developed wrought superalloy with various Fe contents was studied both experimentally and thermodynamically. The results show that the γ′-solvus temperature is higher and γ–γ′ lattice mismatch is bigger in the alloy with the lower Fe content. During long-term thermal exposure at 650–750 °C, the coarsening behavior of γ′ precipitates follows Ostwald ripening kinetics and the lower Fe content can decrease the coarsening rate of γ′ precipitates due to the increase of the activation energy for γ′ coarsening. Moreover, the lower Fe content can retard the transformation from γ′ to η phase. The tensile properties of the alloys with different Fe contents are almost same after standard heat treatment. However, after thermal exposure, the decrease of tensile strength in the alloy with lower Fe content is less than that of the alloys with higher Fe content due to the improvement of γ′ stability.
In this paper, we propose a biomechatronic design of an anthropomorphic artificial hand that is able to mimic the natural motion of human fingers. The prosthetic hand has 5 fingers and 15 joints, which are actuated by 5 embedded motors. Each finger has three phalanges that can fulfill flexion-extension movements independently. The thumb is specially designed to move along a cone surface when grasping, and the other four fingers are well developed based on the four-bar link mechanism to imitate the motion of the human finger. To accomplish the sophisticated control schemes, the fingers are equipped with numerous torque and position sensors. The mechanical parts, sensors, and motion control systems are integrated in the hand structure, and the motion of the hand can be controlled through electromyography (EMG) signals in real-time. A new concept for the sensory feedback system based on an electrical stimulator is also taken into account. The low-cost prosthetic hand is small in size (85% of the human hand), of low weight (420 g) and has a large grasp power (10 N on the fingertips), hence it has a dexterous and humanlike appearance. The performance of the prosthetic hand is validated in a clinical evaluation on transradial amputees.
Cloud Computing has become a well-known primitive nowadays; many researchers and companies are embracing this fascinating technology with feverish haste. In the meantime, security and privacy challenges are brought forward while the number of cloud storage user increases expeditiously. In this work, we conduct an in-depth survey on recent research activities of cloud storage security in association with cloud computing. After an overview of the cloud storage system and its security problem, we focus on the key security requirement triad, i.e., data integrity, data confidentiality, and availability. For each of the three security objectives, we discuss the new unique challenges faced by the cloud storage services, summarize key issues discussed in the current literature, examine, and compare the existing and emerging approaches proposed to meet those new challenges, and point out possible extensions and futuristic research opportunities. The goal of our paper is to provide a state-of-the-art knowledge to new researchers who would like to join this exciting new field.
Jing Xu, Shanghai Institute of Microsystem and Information Technology,
Jiang Wang, Shanghai Institute of Microsystem and Information Technology,
Ting Zhou, Shanghai Research Center for Wireless Communications
Relaying is a well known technique to transmit signals from a source to a destination through one or several intermediate nodes (i.e., relay nodes (RNs)) without using increased power at the source [1–4]. In the past decade, many research efforts on relay technologies have been made to improve the cell coverage, enhance the transmission reliability, and increase the system throughput. More recently, RNs have become an important component in a heterogeneous cellular network (HCN) to provide service improvement and coverage extension at hotspots and cell edges. Layer three (L3) RN, which works as an independent base station (BS) except for the use of the wireless backhaul link, is specified in 3rd Generation Partnership Project (3GPP) Release 10 to realize flexible network deployment and increase network throughput without any additional infrastructure.
In terms of data forwarding, four types of relay have been widely studied, which are amplify-and-forward (AF), demodulate-and-forward (DMF), decode-and-forward (DCF), and estimate-and-forward (EF). Because there is no baseband signal processing function, an AF-relay-based wireless network is cost efficient. The main disadvantage of the AF relay is that the received noise and interference would also be forwarded to the destination. To mitigate the received noise and interference at an RN, the DMF relay and EF relay have been proposed to perform some simple signal processing according to the constellation used. With the decoding operation performed at the RN, a DCF relay can regenerate the source-transmitted signal perfectly if the received signal is decoded correctly.
Dust is a crucial component of galaxies in modifying the observed properties of galaxies. Previous studies have suggested that dust reddening in star-forming galaxies is correlated with star formation rate (SFR), luminosity, gas-phase metallicity (Z), stellar mass (M*) and inclination. In this work we investigate the fundamental relations between dust reddening and physical properties of galaxies, and obtain a well-defined empirical recipe for dust reddening. The empirical formulae can be incorporated into semi-analytical models of galaxy formation and evolution to estimate the dust reddening and facilitate comparison with observations.
NaGd(WO4)2:Eu3+ nanotubes have been successfully synthesized by the hydrothermal method using carbon nanotubes (CNTs) as removable templates. X-ray diffraction, thermogravimetric and differential thermal analysis, transmission electron microscopy, and photoluminescence were used to characterize the product. It is demonstrated that CNTs are fully coated with an amorphous NaGd(WO4)2:Eu3+ layer, which is about 7 nm thick and almost continuous and uniform. After the NaGd(WO4)2:Eu3+/CNTs composites have been calcined at 500 or 600 °C, NaGd(WO4)2:Eu3+ nanotubes are obtained by removing the CNTs templates, and the outer diameter of that is about 40 nm. The luminescence properties of the NaGd(WO4)2:Eu3+ nanotubes calcined at various temperatures have been investigated. The results indicate that the products exhibit a characteristic red emission peak of Eu3+ ions at 615 nm. The emission intensity decreases with the increasing of annealing temperature, which is probably because a few residual carbons doped in NaGd(WO4)2:Eu3+ nanotubes and many oxygen vacancies could promote the intensity of red emission of Eu3+.
A-Weyl's theorem and property (ω), as two variations of Weyl's theorem, were introduced by Rakočević. In this paper, we study a-Weyl's theorem and property (ω) for functions of bounded linear operators. A necessary and sufficient condition is given for an operator T to satisfy that f(T) obeys a-Weyl's theorem (property (ω)) for all f ∈ Hol(σ(T)). Also we investigate the small-compact perturbations of operators satisfying a-Weyl's theorem (property (ω)) in the setting of separable Hilbert spaces.
Sb-rich Si-Sb-Te phase change materials with different Si contents were proposed and fabricated, and the role of Si and Sb in the Si-Sb-Te alloys was discussed. The resistance-temperature and retention properties of the Sb-rich Si-Sb-Te alloys were studied. Devices based on the Sb-rich Si-Sb-Te alloys were fabricated by a 0.18 μm CMOS technology and device properties were studied by pulsed mode resistance-voltage (R-V) measurements. Experimental results show that the crystallization temperature and data retention ability of the Sb-rich Si-Sb-Te alloys were obviously improved with increasing Si content, but the electrical properties degenerate if too much Si was added. Sb is helpful to promote the crystallization process, but excessive Sb decreases the thermal stability. So, in order to obtain practicable Sb-rich Si-Sb-Te phase change materials, suitable Si and Sb contents are required to balance the device performances between electrical switching property and thermal stability or data retention ability.
We performed density-functional calculations of oxygen incorporation and diffusion in layered Ti2AlC for a range of intrinsic- and impurity-element chemical potentials. In view of the thermal equilibrium coexistence between oxygen-dissolved Ti2AlC and the oxide scale, a thermodynamic scheme is presented that allows the comparison of the relative stability of oxygen defects in different exterior environments. The calculations show that the oxygen atom favors substitution on carbon lattice sites (OC) under oxygen-lean conditions and high temperatures, whereas the occurrence of an oxygen interstitial in the aluminum atomic layer (IO-tri) becomes more preferential in an oxygen-rich atmosphere and low temperatures. Interstitial oxygen (IO-tri) diffusion via a metastable interstitial site (IO-oct) has a comparatively low migration energy. The substitutional oxygen defect (OC) diffuses by exchanging with neighboring carbon vacancy, which needs a relatively high diffusion barrier.
Recent work (Baskin & Laor 2004; Dong et al. 2009a, b) suggests that the Eddington ratio (l ≡ L/LEdd) is the origin of all the significant first-order object-to-object variations of quasar spectral properties from the zeroth-order similarity of AGN spectra; specifically, this includes the PC1 of Boroson & Green (1992), the classic or inverse Baldwin effect (Baldwin 1977), and even blueshifting (i.e., blue asymmetry) of high-ionization emission lines (Dong et al. 2009c).
Bulk hybrid polymethyl methacrylate (PMMA)/SiO2 glass with Sb2S3 nanocrystals was prepared by the sol-gel process. We tried to minimize the quantity of water as much as possible in tetraethyl orthosilicate (TEOS) hydrolyzing, prepolymerized the organic monomers, mixed inorganic precursors, and prepolymerized organic monomers under a noncosolvent condition to reduce possible volume shrinkage. A silane coupling agent, which hydrolyzed simultaneously with TEOS, was introduced into the system to improve the miscibility of the organic and inorganic materials. The maximum dopant of Sb2S3 was 9 wt% in our experiments. The second-harmonic generation was observed in the hybrid PMMA/SiO2 glasses with electron-beam poling. Second-harmonic intensity increased with increase of accelerating voltage, current, and the content of Sb2S3 nanocrystals. The maximum χ2 in our study, as large as 1.64 p.m./V, was obtained under the optimized poling condition conducted at 25 kV, 20 nA, and 10 min. It was indicated from the thermally stimulated depolarization current measurements that the nonlinear layer was located in the thin 10-μm irradiated surface of the glass.
MAX-phase carbides (M is an early transition metal, A is an A-group element) exhibit an interesting bonding characteristic of alternative stacking of strong M–C bonds and relatively weak M–A bonds in one direction. In the present first-principles total energy calculations, we establish the relationship between mechanical properties and electronic structure for ternary M2AC (M = Ti, V, Cr, A = Al, Si, P, S) carbides. By systematically tuning elements on the M and A sites, pronounced enhancements of bulk modulus, elastic stiffness, and ideal shear strength are achieved in V-containing V2AC (A = Al, Si, P, and S) carbides. It is suggested that tailoring on the A site is more efficient than on the M site in strengthening the mechanical properties of studied serial carbides. The results highlight a general trend for tailor-made mechanical properties of ternary M2AC carbides by control of chemical bonding.
Layered ternary T-Al-C ceramics containing early transition metal Sc, Zr, and Hf, crystallize with the TnAl3Cn+2 formula, while others containing neighbor elements Ti, V, Cr, Nb, Mo, W, and Ta yield the Tn+1AlCn formula. Ternary TnAl3Cn+2 ceramics are structurally characterized by NaCl-type TC slabs being separated by Al4C3-type AlC layers. In the present study, we suggest that the ability of forming the TnAl3Cn+2 carbide could be traced back to the structure mismatches between the TC, Al4C3 and TnAl3Cn+2 compounds. Ternary carbides following the TnAl3Cn+2 formula experience small lattice mismatches and strain energies. Moreover, the discrepancy between crystal structures of TnAl3Cn+2 and Tn+1AlCn is interpreted by lattice mismatch and the produced strain energy for the ternary T-Al-C ceramics. We also present close relationships between the atomic radii of transition metal and lattice mismatch, as well as the strain energy. The proposed method is not only helpful to explain the trend in crystal structure of T-Al-C based ceramics, but may be also general to predict the crystal structure of layered compounds constructed by alternatively stacked structural units.
Target region amplified polymorphism (TRAP) was used to compare genetic structures among three populations of grass carp (Ctenopharyngodon idella) – one wild and two cultured populations. Seven out of 15 primer combinations produced good amplification patterns and provided 103 amplified loci from the three populations. Numbers of polymorphic loci in the wild population were higher, indicating a decrease in genetic polymorphism in the two cultured populations. Compared with the wild population, only 39.98% loci gene frequency remained unchanged in the cultured samples, showing a genetic structure change in cultured populations. The genetic distances between wild and cultured populations were 0.0421 and 0.0809. With primer combination Ga5-800-E5, we detected a region in the electrophoretic pattern in which the number of amplified loci apparently decreased in cultured populations. These results establish a good scientific basis for developing molecular markers that can help in distinguishing wild from cultured populations.