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Wheat is sensitive to high temperatures, but the spatial and temporal variability of high temperature and its impact on yield are often not known. An analysis of historical climate and yield data was undertaken to characterize the spatial and temporal variability of heat stress between heading and maturity and its impact on wheat grain yield in China. Several heat stress indices were developed to quantify heat intensity, frequency, and duration between heading and maturity based on measured maximum temperature records of the last 50 years from 166 stations in the main wheat-growing region of China. Surprisingly, heat stress between heading and maturity was more severe in the generally cooler northern wheat-growing regions than the generally warmer southern regions of China, because of the delayed time of heading with low temperatures during the earlier growing season and the exposure of the post-heading phase into the warmer part of the year. Heat stress between heading and maturity has increased in the last decades in most of the main winter wheat production areas of China, but the rate was higher in the south than in the north. The correlation between measured grain yields and post-heading heat stress and average temperature were statistically significant in the entire wheat-producing region, and explained about 29% of the observed spatial and temporal yield variability. A heat stress index considering the duration and intensity of heat between heading and maturity was required to describe the correlation of heat stress and yield variability. Because heat stress is a major cause of yield loss and the number of heat events is projected to increase in the future, quantifying the future impact of heat stress on wheat production and developing appropriate adaptation and mitigation strategies are critical for developing food security policies in China and elsewhere.

Higher temperatures caused by future climate change will bring more frequent heat stress events and pose an increasing risk to global wheat production. Crop models have been widely used to simulate future crop productivity but are rarely tested with observed heat stress experimental datasets. Four wheat models (DSSAT-CERES-Wheat, DSSAT-Nwheat, APSIM-Wheat, and WheatGrow) were evaluated with 4 years of environment-controlled phytotron experimental datasets with two wheat cultivars under heat stress at anthesis and grain filling stages. Heat stress at anthesis reduced observed grain numbers per unit area and individual grain size, while heat stress during grain filling mainly decreased the size of the individual grains. The observed impact of heat stress on grain filling duration, total aboveground biomass, grain yield, and grain protein concentration (GPC) varied depending on cultivar and accumulated heat stress. For every unit increase of heat degree days (HDD, degree days over 30 °C), grain filling duration was reduced by 0.30-0.60%, total aboveground biomass was reduced by 0.37-0.43%, and grain yield was reduced by 1.0-1.6%, but GPC was increased by 0.50% for cv Yangmai16 and 0.80% for cv Xumai30. The tested crop simulation models could reproduce some of the observed reductions in grain filling duration, final total aboveground biomass, and grain yield, as well as the observed increase in GPC due to heat stress. Most of the crop models tended to reproduce heat stress impacts better during grain filling than at anthesis. Some of the tested models require improvements in the response to heat stress during grain filling, but all models need improvements in simulating heat stress effects on grain set during anthesis. The observed significant genetic variability in the response of wheat to heat stress needs to be considered through cultivar parameters in future simulation studies.

Performance in both frequency‐domain and time‐domain for a printed super‐wideband antenna is studied and presented in this article. The proposed antenna consists of a corner‐rounded ground plane, a tapered microstrip feeder and a novel radiating patch which is made by one half‐disc and one half‐ellipse. This configuration allows to implement a ratio impedance bandwidth more than 25:1 for voltage standing wave ratio (VSWR) < 2. Critical antenna characteristics including antenna transfer function, group delay and time‐domain pulse responses are experimentally investigated and analyzed in detail by setting up a transceiving antenna system, which give designers a thorough understanding and useful information about antenna performance and application it exhibits behind the extremely broad bandwidth. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 949–956, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24222

Four [Cu2I2]- or [Cu4I4]-based coordination polymers, [CuI(bpp)] n (1), {[Cu3I3(bpp)3]·2aniline·MeCN} n (2), {[Cu2I2(bpp)2]·2aniline} n (3), and [Cu4I4(bpp)2] n (4), were prepared by solvothermal reactions of CuI or Cu2(OH)2CO3 with 1,3-bis(4-pyridyl)propane (bpp) in different solvent systems. The preparation of 2 or 3 is involved in the in situ formation of aniline molecules and the reduction of Cu(II) to Cu(I). These compounds were characterized by elemental analysis, IR, and single crystal X-ray diffraction. Compound 1 consists of [Cu2I2] dimeric cores that link the neighboring ones via bpp bridges to form a one-dimensional double-bridged polymeric chain. Compound 2 or 3 has a similar chain structure in which the shape and size of the [Cu2I2(bpp)2]2 cavities that are occupied by MeCN/aniline or aniline solvent molecules are different from those of 1. Compound 4 has an intriguing two-dimensional 4-fold interpenetrated network in which each cubanelike [Cu4I4] core acts as a rare “seesaw”-shaped four-connecting node to interconnect four other equivalent ones via bpp bridges. The results did provide interesting insights into solvent effects on the construction of cluster-based coordination polymers. In addition, the photoluminescent properties of 1−4 in the solid state at ambient temperature were also investigated.

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This letter describes an asymmetrical coplanar strip (ACPS) wall to suppress the mutual coupling between two closely spaced 5.8-GHz microstrip antennas. The ACPS wall, which is inserted vertically between the two antennas, introduces an additional coupling path to reduce the antenna coupling, occupying just a small area between the two antennas. The decoupling effect of the proposed structure is verified by the simulation and measurement. The experimental results show that the achieved isolation is better than 35 dB and reaches a maximum of 54.3 dB at 5.8 GHz, with an extremely close antenna distance of 0.030 (edge-to-edge distance). The measured patterns indicate that the proposed structure also improves the radiation of the microstrip antenna.

Aims To explore the quantitative dose–response association of total sedentary behaviour and television viewing with overweight/obesity, type 2 diabetes and hypertension in a meta‐analysis. Materials and methods We searched three databases to identify English‐language reports that assessed the association of total sedentary behaviour or television viewing with the aforementioned health outcomes. Restricted cubic splines were used to evaluate possible linear or non‐linear associations of total sedentary behaviour and television viewing with these health outcomes. Results We included 48 articles (58 studies) with a total of 1 071 967 participants in the meta‐analysis; 21 (six cohort and 15 cross‐sectional) studies examined the association of total sedentary behaviour with overweight/obesity, 23 (13 cohort and 10 cross‐sectional) studies examined the association with type 2 diabetes and 14 (one cohort and 13 cross‐sectional) studies examined the association with hypertension. We found linear associations between total sedentary behaviour and type 2 diabetes (Pnon‐linearity = 0.190) and hypertension (Pnon‐linearity = 0.225) and a non‐linear association between total sedentary behaviour and overweight/obesity (Pnon‐linearity = 0.003). For each 1‐h/d increase in total sedentary behaviour, the risk increased by 5% for type 2 diabetes and 4% for hypertension. We also found linear associations between television viewing and type 2 diabetes (Pnon‐linearity = 0.948) and hypertension (Pnon‐linearity = 0.679) and a non‐linear association for overweight/obesity (Pnon‐linearity = 0.007). For each 1‐h/d increase in television viewing, the risk increased by 8% for type 2 diabetes and 6% for hypertension. Conclusions High levels of total sedentary behaviour and television viewing were associated with overweight/obesity, type 2 diabetes and hypertension.