Northward-shift of temperature zones in China＇s eco-geographical study under future climate scenario

Despite the well-documented effects of global climate change on terrestrial species＇ ranges, eco-geographical regions as the regional scale of ecosystems have been poorly studied especially in China with diverse climate and ecosystems. Here we analyse the shift of temperature zones in eco-geographical study over China using projected future climate scenario. Projected climate data with high resolution during 1961-2080 were simulated using regional climate model of PRECIS. The number of days with mean daily temperature above 10℃ and the mean temperature of January are usually regarded as the principal criteria to indicate temperature zones, which are sensitive to climate change. Shifts due to future climate change were calculated by comparing the latitude of grid cells for the future borderline of one temperature zone with that for baseline period （1961-1990）. Results indicated that the ranges of Tropical, Subtropical, Warm Temperate and Plateau Temperate Zones would be enlarged and the ranges of Cold Temperate, Temperate and Plateau Sub-cold Zones would be reduced. Cold Temperate Zone would probably disappear at late this century. North bor- derlines of temperature zones would shift northward under projected future climate change, especially in East China. Farthest shifts of the north boundaries of Plateau Temperate, Subtropical and Warm Temperate Zones would be 3.1°, 5.3° and 6.6° latitude respectively. Moreover, northward shift would be more notably in northern China as future temperature increased.

Low Root Zone Temperature Exacerbates the Ion Imbalance and Photosynthesis Inhibition and Induces Antioxidant Responses in Tomato Plants Under Salinity

The combined effects of salinity with low root zone temperature （RZT） on plant growth and photosynthesis were studied in tomato （Solanum lycopersicum） plants. The plants were exposed to two different root zone temperatures （28/20℃, 12/8℃, day/night temperature） in combination with two NaC1 levels （0 and 100 mmol L-l）. After 2 wk of treatment, K＋ and Na~ concentration, leaf photosynthetic gas exchange, chlorophyll fluorescence and leaf antioxidant enzyme activities were measured. Salinity significantly decreased plant biomass, net photosynthesis rate, actual quantum yield of photosynthesis and concentration of K＋, but remarkably increased the concentration of Na＋. These effects were more pronounced when the salinity treatments were combined with the treatment of low RZT conditions. Either salinity or low RZT individually did not affect maximal efficiency of PSII photochemistry （Fv/Fm）, while a combination of these two stresses decreased Fv/Fm considerably, indicating that the photo-damage occurred under such conditions. Non-photochemical quenching was increased by salt stress in accompany with the enhancement of the de-epoxidation state of the xanthophyll cycle, in contrast, this was not the case with low RZT applied individually. Salinity stress individually increased the activities of SOD, APX, GPOD and GR, and decreased the activities of DHAR. Due to the interactive effects of salinity with low RZT, these five enzyme activities increased sharply in the combined stressed plants. These results indicate that low RZT exacerbates the ion imbalance, PSII damage and photosynthesis inhibition in tomato plants under salinity. In response to the oxidative stress under salinity in combination with low RZT, the activities of antioxidant enzymes SOD, APX, GPOD, DHAR and GR were clearly enhanced in tomato plants.

Effects of Root Zone Temperature on Growth and Photosynthetic Parameters of Grafted Cucumber

Taking Cucurbita maxima and Cucurbita moschata as root stocks,and‘Jinyou No 3＇cucumber as scion,the effects of different root zone temperature conditions optimal temperature（ CK）（ 18-20 ℃）,suboptimal temperature（ 13-15 ℃） and low temperature（ 8-10 ℃） on the growth and photosynthesis indexes were studied. The results showed that,compared with optimal temperature（ CK）,suboptimal temperature and low temperature produced a significant inhibition of growth on cucumbers. The plant height,stem diameter,leaf area,number of leaves and dry weight of aboveground part were all reduced,dry weight of underground part and root shoot ratio all increased,while the inhibition was more significant at low temperature. Low and suboptimal temperature conditions also reduced SPAD value,net photosynthetic rate,transpiration rate,intercellular CO2 concentration and stomatal conductance of the grafted cucumber. And there were differences between different grafted seedlings,and seedlings with‘black seeds＇ as stock performed better than those with‘white seeds＇ as stock at low temperature.

Synthesis of hexagonal boron nitride films by dual temperature zone low-pressure chemical vapor deposition

Hexagonal boron nitride(h-BN)films are synthesized by dual temperature zone low-pressure chemical vapor deposition(LPCVD)through using a single ammonia borane precursor on non-catalytic c-plane Al_(2)O_(3)substrates.The grown films are confirmed to be h-BN films by various characterization methods.Meanwhile,the growth rates and crystal quality of h-BN films at different positions in the dual temperature zone are studied.It is found that the growth rates and crystal quality of the h-BN films at different positions on the substrate are significantly different.The growth rates of the h-BN thin films show their decreasing trends with the rearward position,while the crystal quality is improved.This work provides an experimental basis for the preparation of large area wafer thick h-BN films by LPCVD.

Comparisons of thermogenic features in four coexisting songbirds:Is the northward colonized White-browed Laughingthrush different?

Thermogenic features are often invoked to illustrate animal’s colonization,distribution,and response to climate change.To understand why the White-browed Laughingthrush(Pterorhinus sannio)has expanded its distribution to temperate zones in recent years,we compared its thermogenic features with three species of songbirds that cooccur in its newly colonized areas.Thermogenic parameters of these four species were measured under different ambient temperatures,ranging from 0 to 40℃.The results showed that basal metabolic rate(BMR)was 44.5±3.9 mL O2/h in P.sannio,which is lower than predicted value by its body weight.This is also lower than the BMR of both its temperate congener the Plain Laughingthrush(P.davidi)and the montane,similar species Elliot’s Laughingthrush(Trochalopteron elliotii).The thermal neutral zone(TNZ)in P.sannio was 15-35℃,as compared to 10-27.5℃in P.davidi,25-30℃in T.elliotii,and 7.5-32.5℃in the Green-capped Greenfinch(Chloris sinica).Thermal conductance was lowest in P.sannio,with the minimum value lower than the predicted value based on its body weight.Our results showed that the northward-colonizing P.sannio exhibited different thermogenic characteristics compared with its coexisting species in the new habitat,even its congener P.davidi,which shared similar microhabitats to P.sannio.We suggest that researchers further explore the physiological mechanisms of birds’northward expansion.

INVESTIGATION ON HOT DUCTILITY AND STRENGTH OF CONTINUOUS CASTING SLAB FOR AH32 STEEL

By means of Gleeble-1500 testing machine, the simulation of continuous casting process forAH32 steel was carried out and hot ductility and strength were determined. The cracking sensitivity was studied under the different temperatures and strain rates. The Precipitations of AIN at different temperatures and the fractures of high-temperature tensile samples were observed by using TEM （transmission electron microscope） and SEM （scanning electron microscope）. The factors affecting the brittle temperature zone were discussed.

Modeling De-No_(x) by Injection Ammonia in High Temperature Zone of Cement Precalciner

The quantity of NO_(x) emission from cement production is second only to thermal power generation and vehicle exhaust.In this paper,a phenomenon found by Taniguchi is used to achieve NO_(x) reduction in the cement precalciner.Based on his results,it is proposed to reduce NO_(x) that ammonia is injected in the high-temperature and lean-oxygen zone(HT-DeNO_(x))during pulverized coal combustion.For a large cement precalciner(3200 t/d),numerical simulation is used to evaluate the technology of HT-DeNO_(x) combined with the traditional selective non-catalytic reduction(SNCR)method.The results indicate that NH3 and HCN in HT-DeNO_(x) can reduce NO during the reaction process.With very little ammonia injection(normalized stoichiometric ratio NSR=0.1,the normalized stoichiometric ratio),the efficiency of NO reduction by HT-DeNO_(x) is 27.72%.Combining SNCR(NSR=1.1)and HT-DeNO_(x)(NSR=0.1),the reduction efficiency will be improved to 60.05%,compared with 50.83%efficiency when using only SNCR at NSR=1.2.

Improved root zone temperature buffer capacity enhancing sweet pepper yield via soil-ridged substrate-embedded cultivation in solar greenhouse

A novel soilless cultivation method,called as soil-ridged substrate-embedded cultivation(SSC)was invented,and an experiment was designed to investigate root zone temperature and production efficiency of sweet pepper cultivated by two SSC patterns,i.e.,SSC-P(polyethylene groove inserted)and SSC-W(wire-mesh groove inserted),and also other two cultivation methods,i.e.,soil ridge(SR)and naked polyethylene groove(PG).Results showed that PG,SSC-P and SSC-W increased the average minimal root zone temperature by 1.01℃,0.75℃,and 1.16℃ compared to SR(16.33℃)during March 16-20,2015.During June 1-5,SSC-P and SSC-W decreased the average maximal root zone temperature by 1.28℃ and 1.29℃ compared to SR(34.99℃),while PG increased it by 1.44℃.PG,SSC-P,and SSC-W decreased the differences of average daytime and night time temperatures by 1.34℃,2.13℃,and 2.88℃ compared to SR(4.56℃)during early stage.However,SSC-P and SSC-W decreased temperature differences of average daytime and night time by 0.9℃ and 1.07℃ compared to SR(0.95℃)during later stage,but PG improved by 2.85℃.Temperature difference of daytime and night time of SSC-W was minimal,and the temperature difference between the diurnal highest and the lowest temperature of SSC-W was also minimal.The buffer capacity of SSC-W was slightly better than that of SSC-P.SSC-W significantly improved the growth of sweet pepper compared to SR.Similarly,fruit yield per square meter of sweet pepper cultivated on SSC-P and SSC-W improved by 21.24%and 50.33%,respectively compared to SR(3.06 kg/m^(2)),while PG lowered the yield by 13.72%.SSC-W was a better SSC pattern compared with SSC-P in terms of production efficiency.

Improving harvest efficiency of maize varieties via accumulated temperature in a certain planting area

The ripening and drying of maize(Zea mays L.)grain are closely related to temperature.In accordance with maize grain drying characteristics,regional accumulated temperature(AT0≥0℃)distribution is of great significance for a rational allocation of maize varieties,thus reducing grain moisture content(MC)to improve maize harvest efficiency.From 2016 to 2018,a multi-site trial was carried out in the spring maize production area of Northeastern China.In this study,under a guaranteed rate of 80%for AT0,this area was divided into 15 accumulated temperature zones(ATZs)with an interval of 100℃ based on climatic data of 78 local weather stations.Then the AT0 demand of different maize varieties during different growth stages was calculated by combining experimental records with the established prediction model of MC,and then,the spatial partition for different types of maize varieties under different MCs was analyzed.The results showed that all the tested varieties could not reach physiological maturity(PM)at ATZs 13-15,hence,where maize planting is risky.With the increasing accumulated temperature demand of different types of maize varieties from planting to PM,to the MC of 25%and to the MC of 20%,the unplantable areas were gradually expanded from south to north while the region where the maize varieties could be harvested under different MCs was also moved southwardly.Additionally,at 1-2 ATZs,it is entirely possible to achieve mechanical kernel harvesting under the MC of 20%,even though the AT0 requirements of the varieties are relatively high.Conclusively,on the grounds of AT0 demand law of maize varieties and heat resource distribution in Northeastern China,the layout optimization for achieving different harvesting scenarios is conducive to providing a basis not only for selecting suitable varieties but also for promoting mechanical kernel harvesting in the spring maize production area of this region.

Application of Hot Strength and Ductility Test to Optimization of Secondary Cooling System in Billet Continuous Casting Process

By means of Gleeble-1500 dynamic thermomechanical simulator, the continuous casting process for HRB335C steel was simulated using solidifying method and hot ductility and strength of the steel were determined. The test results indicate that there are three temperature regions of brittleness for HRB335C billet in the temperature range from 700 ℃ to solidification point; the first temperature region of brittleness is 1 300 ℃ to solidification point of the billet, the second temperature region of brittleness is 1 200-- 1 000 ℃, and the third temperature region of brittleness is 700-850 ℃ ; the steel is plastic at 850--1 000 ℃. The cracking sensitivity was studied in the different temperature zones of the brittleness for steel HRB335C and the target surface temperature curve for the secondary cooling is determined. With optimized process, the mathematical model of the steady temperature field with two-dimensional heat transfer for 150 mm×150 mm HRB335C steel billet was established to optimize the secondary cooling process. The conic relation of water distribution between secondary cooling water flux and casting speed is regressed. Keeping the surface temperature of billet before the straightening point above 1 000 ℃, the results of billet test indicate that there is free central shrinkage cavity. The billet defect is decreased greatly, and the quality of billet is obviously improved.