The influence of oxidative-thermal degradation of polypropylene on measured interface strength of glass fibre-polypropylene

It was previously found that thermal-oxidative degradation of the polypropylene could significantly affect the measured interfacial strength of glass fibre reinforced polypropylene (GF-PP) micro-composite. In this work, different approaches have been employed to justify this influence. Hot-stage microscopy was used to establish a degradation profile of PP microdroplets that had different initial dimensions and results revealed that the reduction in droplet dimensions was affected by not only its initial droplet size and but also the presence of the fibre in the droplet. The Young's moduli of PP microdroplets with different heat treatments were examined by using nanoindentation technique and the results showed that there was significant stiffness deterioration in degraded samples and the severity is also related to the droplet size for a given heat treatment. Comparison of adhesion for GF-PP was also made between degraded and non-degraded samples. It shows that non-degraded samples give much higher values for interface strength of GF-PP than degraded ones

Eco-physiological response to fertility and landform for spring wheat under rainfed environment in hummocky terrain, Saskatchewan, Canada

Non-Peer ReviewedThe experiment was made throughout the 1992 growing season on upper and lower slope positions at a site near Lanigan, Saskatchewan. Soil water reserves to 120 cm on the footslope was 38% more than on the shoulder at the beginning of the growing period, and the difference decreased gradually with wheat growth, Soil temperature on the lower slope at both the 50 cm depth and 100 cm depth was higher than on the upper slope before mid-July, whereas the opposite was true afterwards. Latent evaporation on the shoulder was higher than on the footslope. Significant differences occurred between slope positions as well as between fertilizer treatments for both the development of leaf area indices and for the accumulation of above ground biomass. Throughout the growing season, leaf water potentials indicated a high level of stress occurred in all treatments, with the shoulder position exhibiting the greatest stress. No significant difference of leaf water potential occurred between fertilizer treatments. Fertilizer application increased both total and grain yields, and raised water use efficiency, on both slope positions. The effect of the amount of precipitation in flowering-filling stage on harvest indices was enhanced with fertilizer application

Expression of wheat gibberellins 2-oxidase gene induced dwarf or semi-dwarf phenotype in rice

Gibberellins (GAs) are a class of plant hormones that play important roles in diverse aspects during plant growth and development. A series of GA synthesis and metabolism genes have been reported or proved to have essential functions in different plant species, while a small number of GA 2-oxidase genes have been cloned or reported in wheat. Previous studies have provided some important findings on the process of GA biosynthesis and the enzymes involved in its related pathways. These may facilitate understanding of the complicated process underlying GA synthesis and metabolism in wheat. In this study, GA 2-oxidase genes TaGA2ox1-1, TaGA2ox1-2, TaGA2ox1-3, TaGA2ox1-4, TaGA2ox1-5, and TaGA2ox1-6 were identified and further overexpressed in rice plants to investigate their functions in GA biosynthesis and signaling pathway. Results showed overexpression of GA 2-oxidase genes in rice disrupted the GA metabolic pathways and induced catalytic responses and regulated other GA biosynthesis and signaling pathway genes, which further leading to GA signaling disorders and diversity in phenotypic changes in rice plants

Study on the Failure Mechanism of the Polymorphic Mixture for Remanifactured Machinery Parts

The polymorphic mixture failure mode for multiple heterogeneity of remanifactured (RM) machinery parts makes it difficult to assess their lifetime. The Weibull distribution failure model of RM parts (substrate, coating layer, bonding surface and sudden failure) is constructed with failure time statistics of the parts in service, the latter is used to characterize the failure patterns of RM parts. In view of the multiple heterogeneity of RM parts, the Kaplan–Meier type decoupling method is used to analyze four sets of failure statistics, and each state of the Weibull failure function of the above parts is solved. It reveals the in-service failure mechanism of polymorphic mixtures for multiple heterogeneity of RM machinery parts. The validity and feasibility of the model are verified by the case study. Research results provide the theoretical basis for the design and preparation of a RM alloy powder and the improvement of RM technology. Moreover, the method for lifetime prediction and failure time evaluation of RM parts is proposed and validatedХарактер разрушения полиморфной смеси в условиях множественной гетерогенности модифицированных деталей затрудняет оценку срока службы оборудования. Модель разрушения распределения Вейбулла (разрушение подложки, наружного слоя, поверхости сцепления, мгновенное разрушение) построена на основании статистических данных о времени разрушения детелей в условиях эксплуатации. Использован метод разделения Каплана Мейера для анализа четырех множеств статистик разрушения, выполнено решение каждого состояния функции Вейбулла, что позволило установить механизм разрушения полиморфных смесей в условиях эксплуатации при множественной гетерогенности модифицированных деталей оборудования. На примере выполнения моделирования верифицированы достоверность и применимость модели. Создана теоретическая основа для разработки и изготовления порошка сплава и совершенствования технологии модифицирования. Разработан метод прогнозирования срока службы и оценки периода разрушения модифицированных деталей

Direct Production of Lightest Regge Resonances

We discuss direct production of Regge excitations in the collisions of massless four-dimensional superstring states, focusing on the first excited level of open strings ending on D-branes extending into higher dimensions. We construct covariant vertex operators and identify ``universal'' Regge states with the internal parts either trivial or determined by the world-sheet SCFT describing superstrings propagating on an arbitrary Calabi-Yau manifold. We evaluate the amplitudes involving one such massive state and up to three massless ones and express them in the helicity basis. The most important phenomenological applications of our results are in the context of low-mass string (and large extra dimensions) scenarios in which excited string states are expected to be produced at the LHC as soon as the string mass threshold is reached in the center-of-mass energies of the colliding partons. In order to facilitate the use of partonic cross sections, we evaluate them and tabulate for all production processes: gluon fusion, quark absorbing a gluon, quark-antiquark annihilation and quark-quark scattering.Comment: 43 pages, RevTeX 4.

Review: Progress in the Studies on Mechanical Properties of Materials

Materials science and engineering is one of the hot research topics in the world, among which mechanical properties of materials play a critical role in application of the new materials. Based on this, a special session Mechanical Properties of Materials was held within the 2nd Global Conference on Materials Science and Engineering, Nov. 20–22, 2013. This special issue contains a selection of twenty scientific papers, which are focused on the structure, mechanical properties, and strength of materials. In this review, the selected papers from the special session are summarized.Материаловедение и инженерия относятся к наиболее актуальным направлениям научных исследований в мире, а применение новых материалов в значительной степени основывается на изучении механических свойств материалов. Исходя из этого в рамках 2-й Глобальной конференции по материаловедению и инженерии 20–22 ноября 2013 года была проведена специальная сессия по вопросам исследования механических свойств материалов. Этот специальный номер содержит подборку из 20 научных работ, отобранных из числа всех докладов, посвященных проблемам структуры, механических свойств и прочности материалов. В данном обзоре обсуждаются отдельные доклады специальной сессии, представленные в этом номере журнала.Матеріалознавство та інженерія відносяться до найбільш актуальних напрямків наукових досліджень у світі, тоді як використання нових матеріалів у значній мірі базується на дослідженні механічних властивостей матеріалів. Виходячи з цього, у межах 2-ї Глобальної конференції з матеріалознавства й інженерії 20–22 листопада 2013 року було проведено спеціальну сесію з питань дослідження механічних властивостей матеріалів. Цей спеціальний номер містить добірку з 20 наукових робіт,відібраних із числа всіх доповідей, присвячених проблемам структури, механічних властивостей і міцності матеріалів. У даному огляді обговорюються окремі доповіді спеціальної сесії, представлені в цьому номері журналу

Time-Dependent Partition-Free Approach in Resonant Tunneling Systems

An extended Keldysh formalism, well suited to properly take into account the initial correlations, is used in order to deal with the time-dependent current response of a resonant tunneling system. We use a \textit{partition-free} approach by Cini in which the whole system is in equilibrium before an external bias is switched on. No fictitious partitions are used. Besides the steady-state responses one can also calculate physical dynamical responses. In the noninteracting case we clarify under what circumstances a steady-state current develops and compare our result with the one obtained in the partitioned scheme. We prove a Theorem of asymptotic Equivalence between the two schemes for arbitrary time-dependent disturbances. We also show that the steady-state current is independent of the history of the external perturbation (Memory Loss Theorem). In the so called wide-band limit an analytic result for the time-dependent current is obtained. In the interacting case we propose an exact non-equilibrium Green function approach based on Time Dependent Density Functional Theory. The equations are no more difficult than an ordinary Mean Field treatment. We show how the scattering-state scheme by Lang follows from our formulation. An exact formula for the steady-state current of an arbitrary interacting resonant tunneling system is obtained. As an example the time-dependent current response is calculated in the Random Phase Approximation.Comment: final version, 18 pages, 9 figure

Theoretical study of the two-proton halo candidate 17^{17}Ne including contributions from resonant continuum and pairing correlations

With the relativistic Coulomb wave function boundary condition, the energies, widths and wave functions of the single proton resonant orbitals for $^{17}$Ne are studied by the analytical continuation of the coupling constant (ACCC) approach within the framework of the relativistic mean field (RMF) theory. Pairing correlations and contributions from the single-particle resonant orbitals in the continuum are taken into consideration by the resonant Bardeen-Cooper-Schrieffer (BCS) approach, in which constant pairing strength is used. It can be seen that the fully self-consistent calculations with NL3 and NLSH effective interactions mostly agree with the latest experimental measurements, such as binding energies, matter radii, charge radii and densities. The energy of $\pi$2s$_{1/2}$ orbital is slightly higher than that of $\pi1d_{5/2}$ orbital, and the occupation probability of the $(\pi$2s$_{1/2})^2$ orbital is about 20%, which are in accordance with the shell model calculation and three-body model estimation