Comparison of electrohysterogram characteristics during uterine contraction and non-contraction during labor

Uterine contraction is one of the most important indication in the labor progression. Electrohysterogram (EHG) is a promising method for monitoring uterine contraction and discriminating efficient and inefficient contractions. This study aims to analyze the difference of EHG signals between two groups. EHG signals are recorded with abdominal electrodes from 20 pregnant women, including 10 in term labor group and 10 in non-labor group. Typical linear and nonlinear characteristics of EHG signals, including root mean square (RMS), peak frequency (PF), median frequency (MDF), mean frequency (MNF), parameters from wavelet decomposition (W4, W5) and time reversibility (Tr) are extracted. These characteristics are compared between contraction and non-contraction in term labor group and non-labor group. The result shows that RMS, W4 and W5 of contraction are significantly larger than non-contraction both within term labor group and between two groups (all p<;0.001). However, MDF and MNF are significantly smaller (all p<;0.05). Furthermore, all characteristics of non-contraction show no significant difference between two groups, except MNF. The variability of RMS, W4, W5 and Tr of contraction are significantly larger than non-contraction both within term labor group and between two groups (all p<;0.05, with p<;0.001 for W5 and Tr). However, the variability of MDF, PF and MNF are significantly smaller (all p<;0.05). Moreover, the variability of all characteristics of non-contraction shows no significant difference between two groups, except MNF. We have shown that characteristics of EHG signals and their variability during contraction are quite different from non-contraction. Therefore, it is feasible to separate uterine contractions and monitor uterine activity with EHG signals

Vehicle emission and atmospheric pollution in China: problems, progress, and prospects

China has been the largest vehicle market in the world since 2009. The stalemate between the rapid development of the vehicle industry and delayed vehicle emission control has become increasingly prominent. Vehicle emission has become a significant source of air pollution in China’s cities. Understanding the current barriers in the vehicle industry is necessary for the development of effective and sustainable measures and policy to manage vehicle-induced air pollution. This review provides insight into the circumstances and causes of vehicle-induced air pollution and outlines recent progress in policy-makers’ long-term strategies and regulations. The development of an integrated mechanism of social participation, technical revolution, and regulatory innovation in vehicles, fuel, and roads is suggested to break the stalemate between air pollution and the automobile boom in China; the implications of this review extend to other countries facing the similar atmospheric pollution problems

A study on the erosion and erosion-oxidation of metal matrix composites

The potential of metal matrix composites (MMCs) as new generation erosion and erosioncorrosion resistant materials is investigated. As a type of wear attack, erosion involves destructive impact of free-moving particles on a solid. The high-strain-rate and hence adiabatic deformation conditions that the target surface experiences during erosion are often the reasons behind the poor correlation of erosion rate with static mechanical properties of the targets, imparting difficuties on erosion study. On the other hand, a good correlation exists between erosion rate and the thermophysical properties of the target. This, however, suggests limited possibilities of enhancing erosion resistance on a monolithic alloy. A literature study at the beginning elaborates the complex of erosion as a physical phenomenon, and lies the theoretical base for the experiment. In the experiment, nickel-chromium superalloy- and heat resistant steel-based composites are manufactured through a powder metallurgy route. Ceramic particles are added at different volume fractions as the reinforcements. Efforts are made to optimise the powder mixing and powder consolidation procedures to ensure a homogeneous microstructure and full densification of the final composites. Two types of erosion tester are used in the study: a centrifugal erosion tester is for the erosion tests at room temperature, and a gas-blast erosion tester is for the erosion-oxidation tests at high temperature. With the gas-blast tester, both the temperature and oxygen concentration is controlled to simulate real application situations. The discussion is focused on the tests under a 60° angle of impact. Optical and SEM (scanning electron microscopy) observations are carried out on the eroded surfaces to assess the damage pattern and general behaviour of the studying composites. Meanwhile, on cross-sectioned specimens the bonding and material dissolution at the matrix/reinforcement interfacial regions and the deformation situation at the sub-surfaces are examined by EDS (energy dispersion spectroscopy) and microhardness measurements to reveal the erosion mechanisms of the composites. The experimental results suggest that the strain localisation mode is valid in describing erosion process of a ductile metal, but may need modifications when applying to MMCs. The erosion response of a MMC system is determined by not only the internal parameters of the composites, but also external factors involving all parameters of erosion. In addition, this study provides useful guidelines to the selection of composite systems having high erosion resistance for industrial applications and to the future study as well.reviewe

Magnetic properties of lithium zinc ferrites synthesized by microwave sintered method

In this paper, a series of polycrystalline ferrite samples were prepared with the composition of Zn0.1Li0.525-xTi0.15MgxFe2.225-0.5xO4 (LiZn) (x=0, 0.05, 0.10, 0.15 and 0.20) using both microwave sintering (MS) and conventional sintering (CS) technologies, respectively. The sintering time and temperature were 22 hours and 1000°C for the CS process, and 2 hours and 880°C for the MS process. Experiments showed that the MS treated LiZn ferrites exhibited more excellent magnetic properties and denser, more uniform micro-structures comparing with the ones treated by CS method. For the LiZn ferrite (x=0.1) sintered at 880°C using MS, the saturation magnetic induction (Bs) is 242.3 mT, the coercive force (Hc) is 135 A/m, the square ratio (Br/Bs) is 0.87 and the ferromagnetic resonance line-width (Δ H) is 143.2 Oe. These results represented very good properties for an X-band phase shifter material and indicated that the MS method is a potentially important technique for fabricating low temperature co-fired ceramics (LTCC)

Carrier–Carrier Repulsion Limits the Conductivity of N-Doped Organic Semiconductors

Molecular doping is a key strategy to enhance the electrical conductivity of organic semiconductors. Typically, the electrical conductivity shows a maximum value upon increased doping, after which the conductivity decreases. This decrease in conductivity is commonly attributed to unfavorable changes in the morphology. However, in recent simulation work, has shown, that the conductivity—at high doping—is instead limited by electron–electron repulsion rather than by morphology, at least for some material combinations. Based on the simulations, this limitation is expected to show up in the dependence of the Seebeck coefficient versus carrier density: the Seebeck coefficient will follow Heike's formula if carrier–carrier repulsion limits the conductivity. Here, the electrical conductivity and Seebeck coefficient are measured as a function of doping for a series of n-type organic semiconductors. Additionally, the resulting carrier density is measured using metal-insulator-semiconductor diodes, which link dopant loading and the number of charge carriers. At high carrier densities, the Seebeck coefficient indeed follows Heike's formula, confirming that the conductivity is limited by carrier–carrier repulsion rather than by morphological effects. This study shows that current models of hopping transport in organic semiconductors may be incomplete. As a result, this study offers novel insights in the design of organic semiconductors.</p

Speedy Error Reconciliation

Introducing small errors in the lattice-based key exchange protocols, although it is resistant to quantum computing attacks, will cause both parties to only get roughly equal secret values, which brings uncertainty to the negotiation of the key agreement. The role of the error reconciliation mechanism is to eliminate this uncertainty and ensure that both parties can reach a consensus. This paper designs a new error reconciliation mechanism: Speedy Error Reconciliation (SER), which can efficiently complete key negotiation while ensuring key correctness and security. SER exploits the properties of the approximate secret values σ1 and σ2 shared by the two parties, and simultaneously reconciles the most and least significant bits of the secret value, and a two-bit key can be obtained by one coordination. By sharing g-bit auxiliary information between two entities, SER expands the fault tolerance interval during reconciliation and improves the success rate of consensus. To test the actual performance of SER, we integrate it into key ex- change protocols based on LWE, RLWE, and MLWE, such as Frodo and NewHope. By comparing parameters such as failure rate, security strength, and the number of CPU rounds, we find that SER performs well in various modes, especially in RLWE-based protocol. Since SER doubles the error to reconcile the least significant bit, which in turn leads to a relatively large error in SER; while the RLWE-based key ex- change scheme adopts a polynomial ring and selects a large parameter q, which is very suitable for SER. Compared with Frodo and NewHope, SER improves the reconciliation efficiency of the per-bit key by 61.6% and 797.6%, respectively

Ultrastructure of Ediacaran cloudinids suggests diverse taphonomic histories and affinities with non-biomineralized annelids

Cloudinids have long been considered the earliest biomineralizing metazoans, but their affinities have remained contentious and undetermined. Based on well-preserved ultrastructures of two taxa, we here propose new interpretations regarding both their extent of original biomineralization and their phylogenetic affinity. One of these taxa is a new cloudinid from Mongolia, Zuunia chimidtsereni gen. et sp. nov., which exhibits key characteristics of submicrometric kerogenous lamellae, plastic tubewall deformation, and tube-wall delamination. Multiple carbonaceous lamellae are also discovered in Cloudina from Namibia and Paraguay, which we interpret to have originated from chitinous or collagenous fabrics. We deduce that these cloudinids were predominantly originally organic (chitinous or collagenous), and postmortem decay and taphonomic mineralization resulted in the formation of aragonite and/or calcite. Further, based on our ultrastructural characterization and other morphological similarities, we suggest that the cloudinids should most parsimoniously be assigned to annelids with originally organic tubes

Controlling n-Type Molecular Doping via Regiochemistry and Polarity of Pendant Groups on Low Band Gap Donor-Acceptor Copolymers

We demonstrate the impact of the type and position of pendant groups on the n-doping of low-band gap donor-acceptor (D-A) copolymers. Polar glycol ether groups simultaneously increase the electron affinities of D-A copolymers and improve the host/dopant miscibility compared to nonpolar alkyl groups, improving the doping efficiency by a factor of over 40. The bulk mobility of the doped films increases with the fraction of polar groups, leading to a best conductivity of 0.08 S cm(-1) and power factor (PF) of 0.24 mu W m(-1) K-2 in the doped copolymer with the polar pendant groups on both the D and A moieties. We used spatially resolved absorption spectroscopy to relate commensurate morphological changes to the dispersion of dopants and to the relative local doping efficiency, demonstrating a direct relationship between the morphology of the polymer phase, the solvation of the molecular dopant, and the electrical properties of doped films. Our work offers fundamental new insights into the influence of the physical properties of pendant chains on the molecular doping process, which should be generalizable to any molecularly doped polymer films