Ranges of critical temperature and water potential values for the germination of species worldwide: Contribution to a seed trait database

Germination is the first essential stage in crop and food production, as well as for the establishment of trees and regeneration of wild species. Temperature and water potential are the primary environmental factors that control germination in all species, and affect both the rate and final percentage germination. A comprehensive description of intra- and inter-variations between groups of species (perennials and annuals, trees, grasses, crops and wild species) helps understand where these species are currently able to grow on earth and will be in the future. By collecting germination trait data on 243 species from the literature and unpublished data, we provide a wide spectrum of species’ seed germination traits, in the form of a set of parameter values describing germination responses to variations in temperature and water potential. Major differences in germination traits were seen to depend on the climatic conditions where the species grow or originated, with species able to germinate on ice and others unable to germinate below 18 °C. By contrast, within the different plant groups, similar ranges of threshold values were found, linked to the species geo-climatic origin. Crops however germinate faster, their range of threshold temperatures and water potential values is wider, and some crops have higher optimum and maximum temperatures as well as lower water potential threshold values. This is likely the result of human selection for rapid germination and for species able to grow in the wide range of environmental conditions where agriculture was developed. Our analyses revealed correlation between traits: negative correlations appeared between germination speed and temperature thresholds, and between temperature and water potential thresholds. The collected data also form a valuable database, enabling plant establishment to be better taken into account in modeling and simulation studies of vegetation boundaries (wild or cultivated) under changing land-use and climate

Conditional quantitative trait locus mapping of wheat seed protein-fraction in relation to starch content

Protein and starch are important in wheat quality and yield. To understand the genetic relationship between protein and starch at the quantitative trait locus (QTL)/gene level, 168 doubled haploid (DH) lines were used at three locations over 2 years. The QTLs for proteinfraction contents and starch content were analyzed by unconditional and conditional QTL mapping. We detected 17 unconditional additive QTLs (four albumin QTLs, three globulin QTLs, six gliadin QTLs, four glutenin QTLs) controlling protein-fraction contents. We detected 19 conditional QTLs (five albumin QTLs, three globulin QTLs, five gliadin QTLs, six glutenin QTLs) based on starch content. Of these QTLs, QAlu1B, QGlo6A, QGli1B, QGli7A, QGlu1B and QGlu1D increased the protein-fraction contents independent of the starch content. These QTLs could regulate the usual inverse relationship between protein and starch in wheat seeds. The results could possibly be used in the simultaneous improvement of grain protein and starch content in wheat breeding

Thermomechanical Coupling Model for a Stainless Steel-Clad Plate on Heat Treatment

Quick and correct prediction of the internal stress and deformation of stainless steel-clad plates on heat treatment is a problem of specific interest. A thermomechanical coupling model based on the engineering elastic-plastic theory is detailed. The discretization method and difference equations used simultaneously provide effective numerical calculations for the model. The generalized finite element model verifies relevant simplification conditions and efficiency of the numerical calculation logic. Heat treatment experiments of clad plates are also designed and presented, and the ability of the model to predict the stress and deformation behavior of the clad plate in the actual heat treatment process is evaluated. The calculation logic of the model is reasonable, and the prediction error of deformation and internal stress of the plate is ~15%. The model exhibits an extremely high computational efficiency and can meet the requirements of on-line analysis for heat treatment processes.Быстрое и точное прогнозирование внутреннего напряжения и кривизны деформации листов, плакированных нержавеющей сталью, при термообработке остается актуальной проблемой в этой области исследования. Рассматривается модель термомеханической связи листа, основанная на инженерной теории упругих и пластических деформаций. Для реализации эффективного численного расчета модели совместно используются метод дискретизации и разностные уравнения. Применение обобщенной конечноэлементной модели позволяет подтвердить соответствующие условия упрощения и рациональность логики численного расчета модели. Планируются и описываются эксперименты по термообработке таких плакированных листов и анализируется способность модели прогнозировать характер напряжения и деформации плакированного листа в реальном процессе термообработки. Логика расчета модели обоснована, при этом погрешность прогнозирования деформации и внутреннего давления листа составляет ~15%. Модель также имеет очень высокую вычислительную эффективность и может удовлетворять требованиям анализа в режиме он-лайн для процессов термообработки.Швидке і точне прогнозування внутрішніх напружень і кривизни деформації листів, плакованих нержавіючої сталлю, при термообробці залишається актуальною проблемою в цій області дослідження. Розглядається модель термомеханічного зв'язку листа, заснованої на інженерної теорії пружних і пластичних деформацій. Для реалізації ефективного чисельного розрахунку моделі спільно використовуються метод дискретизації і різницеві рівняння. Застосування узагальненої скінченноелементної моделі дозволяє підтвердити відповідні умови спрощення і раціональність логіки чисельного розрахунку моделі. Плануються і описуються експерименти по термообробці таких плакованих листів і аналізується здатність моделі прогнозувати характер напружень і деформації плакованного листа в реальному процесі термообробки. Логіка розрахунку моделі обгрунтована, при цьому похибка прогнозування деформації і внутрішнього тиску листа складає ~ 15%. Модель також має дуже високу обчислювальну ефективність і може задовольняти вимогам аналізу в режимі он-лайн для процесів термообробки

Dynamic Stress Analysis of a Composite Electromagnetic Track

The firing of an electromagnetic gun is shown to result in the armature moving along the guide rail, which can cause extrusion, wear, planing and other problems, which set limits on its application. The track properties can be adjusted by changing its composition, so as to obtain good electrical conductivity, corrosive resistance, and strength. For simplicity, the composite track is presented as an elastic foundation beam, and the general solution of composite track deflection at dynamic load is obtained by using the two-dimensional Fourier integral transformation, on this basis, the bending moment distribution and expression for dynamic stress are obtained. The characteristics of dynamic stress distribution and factors that influence them are analyzed, the effect of the proportion of the composite layer and its parameters on the dynamic stress of the track is discussed.Показано, что выстрел электромагнитной пушки приводит к перемещению брони по направляющей, что может вызывать выталкивание, износ, обдирание и другие процессы, которые налагают ограничения на ее применение. Свойства направляющей могут быть модифицированы путем изменения ее состава, что обеспечит хорошую удельную электропроводность, коррозионную стойкость и прочность. Для простоты композиционная направляющая представлена в виде упругой фундаментной балки, общее решение для прогиба направляющей при динамической нагрузке получают с помощью двухмерного интегрального преобразования Фурье, на его основании получают распределение изгибающего момента и выражение для напряжения при динамической нагрузке. Выполнен анализ характеристик распределения напряжений и влияющих на них факторов. Рассмотрено влияние доли композиционного слоя и его параметров на напряжение направляющей при динамической нагрузке

Geometric nonlinear vibration analysis for pretensioned rectangular orthotropic membrane

The geometric nonlinear vibrations of pretensioned orthotropic membrane with four edges fixed, which is commonly applied in building membrane structure, are studied. The nonlinear partial differential governing equations are derived by von Kármán’s large deflection theory and D’Alembert’s principle. Because of the strong nonlinearity of governing equations, the homotopy perturbation method (HPM) to solve them is applied. The approximate analytical solution of the vibration frequency and displacement function is obtained. In the computational example, the frequency, vibration mode and displacement as well as the time curve of each feature point are analyzed. It is proved that HPM is an effective, simple and high-precision method to solve the geometric nonlinear vibration problem of membrane structures. These results provide some valuable computational basis for the vibration control and dynamic design of building and other analogous membrane structures.Вивчено геометрично нелінійні коливання попередньо напруженої ортотропної мембрани з чотирма фіксованими краями, яка звичайно використовується в будівельних мембранних конструкціях. Нелінійні рівняння динаміки в частинних похідних отримано на базі теорії фон Кармана про великі прогини і принципу Д‘Алямбера. Застосовано метод гомотопічного збурення для розв’язування отриманих сильно нелінійних рівнянь. Отримано наближений аналітичний розвязок для частоти коливань і функції зміщень. У числовому прикладі проаналізовано частоти, форми коливань, зміщення і залежні від часу криві у кожній характерній точці. Доведено, що цей метод є ефективним, простим і високоточним для розвязування задач про геометрично нелінійні коливання мембранних конструкцій. Ці результати створюють певну корисну базу для обчислення задач про управління коливаннями і динамічне конструювання будівельних та інших аналогічних мембранних конструкцій

Quantitative trait loci for the diurnal flag leaf starch content during the early grain-filling stage in wheat (Triticum aestivum L.)

Starch is a product of photosynthetic activities in leaves. Wheat yields largely depend on photosynthetic carbon fixation and carbohydrate metabolism in flag leaves. The mapping of quantitative trait loci (QTLs) associated with flag leaf starch content (FLSC) in wheat (Triticum aestivum L.) was completed using unconditional and conditional QTL analyses. The FLSC of this population during the early grain-filling stage was measured at six stages in six environments. Combining unconditional and conditional QTL mapping methods, eight unconditional QTLs and nine conditional QTLs were detected, with five QTLs identified as unconditional and conditional QTLs. Four unconditional QTLs (i.e. qFLS-1B, qFLS-1D-1, qFLS-4A, and qFLS-7D-1) and one conditional QTL (i.e. qFLS-3A-1) were identified in two of six environments. Two QTLs (qFLS-1D-2 and qFLS-7D-1), which significantly affected the FLSC, were identified using the unconditional QTL mapping method, while three QTLs (i.e. qFLS-1A, qFLS-3A-1, and qFLS-7D-1) were detected using the conditional QTL mapping method. Our findings provide new insights into the genetic mechanism and regulatory network underlying the diurnal FLSC in wheat

Optical properties and radiative forcing of urban aerosols in Nanjing, China

AbstractContinuous measurements of atmospheric aerosols were made in Nanjing, a megacity in China, from 18 January to 18 April, 2011 (Phase 1) and from 22 April 2011 to 21 April 2012 (Phase 2). Aerosol characteristics, optical properties, and direct radiative forcing (DRF) were studied through interpretations of these measurements. We found that during Phase 1, mean PM2.5, black carbon (BC), and aerosol scattering coefficient (Bsp) in Nanjing were 76.1 ± 59.3 μg m−3, 4.1 ± 2.2 μg m−3, and 170.9 ± 105.8 M m−1, respectively. High pollution episodes occurred during Spring and Lantern Festivals when hourly PM2.5 concentrations reached 440 μg m−3, possibly due to significant discharge of fireworks. Temporal variations of PM2.5, BC, and Bsp were similar to each other. It is estimated that inorganic scattering aerosols account for about 49 ± 8.6% of total aerosols while BC only accounted for 6.6 ± 2.9%, and nitrate was larger than sulfate. In Phase 2, optical properties of aerosols show great seasonality. High relative humidity (RH) in summer (June, July, August) likely attributed to large optical depth (AOD) and small Angstrom exponent (AE) of aerosols. Due to dust storms, AE of total aerosols was the smallest in spring (March, April, May). Annual mean 550-nm AOD and 675/440-nm AE were 0.6 ± 0.3 and 1.25 ± 0.29 for total aerosols, 0.04 ± 0.02 and 1.44 ± 0.50 for absorbing aerosols, 0.48 ± 0.29 and 1.64 ± 0.29 for fine aerosols, respectively. Annual single scattering albedo of aerosols ranged from 0.90 to 0.92. Real time wavelength-dependent surface albedo from the Moderate Resolution Imaging Spectroradiometer (MODIS) was used to assess aerosol DRFs. Both total and absorbing aerosol DRFs had significant seasonal variations in Nanjing and they were the strongest in summer. Annual mean clear sky TOA DRF (including daytime and nighttime) of total and absorbing aerosols was about −6.9 and +4.5 W m−2, respectively. Aerosol DRFs were found to be sensitive to surface albedo. Over brighter surfaces, solar radiation was more absorbed by absorbing aerosols and less scattered by scattering aerosols

Non-Markovian dynamics in a spin star system: The failure of thermalization

In most cases, a small system weakly interacting with a thermal bath will finally reach the thermal state with the temperature of the bath. We show that this intuitive picture is not always true by a spin star model where non-Markov effect predominates in the whole dynamical process. The spin star system consists a central spin homogeneously interacting with an ensemble of identical noninteracting spins. We find that the correlation time of the bath is infinite, which implies that the bath has a perfect memory, and that the dynamical evolution of the central spin must be non- Markovian. A direct consequence is that the final state of the central spin is not the thermal state equilibrium with the bath, but a steady state which depends on its initial state.Comment: 8 page