Comparative studies of critical physiological limits and vulnerability to environmental extremes in small ectotherms:How much environmental control is needed?

Researchers and practitioners are increasingly using comparative assessments of critical thermal and physiological limits to assess the relative vulnerability of ectothermic species to extreme thermal and aridity conditions occurring under climate change.In most assessments of vulnerability,critical limits are compared across taxa exposed to different environmental and developmental conditions.However,many aspects of vulnerability should ideally be compared when species are exposed to the same environmental conditions,allowing a partitioning of sources of variation such as used in quantitative genetics.This is particularly important when assessing the importance of different types of plasticity to critical limits,using phylogenetic analyses to test for evolutionary constraints,isolating genetic variants that contribute to limits,characterizing evolutionary interactions among traits limiting adaptive responses,and when assessing the role of cross generation effects.However,vulnerability assessments based on critical thermal/physiological limits also need to take place within a context that is relevant to field conditions,which is not easily provided under controlled environmental conditions where behavior,microhabitat,stress exposure rates and other factors will differ from field conditions.There are ways of reconciling these requirements,such as by taking organisms from controlled environments and then testing their performance under field conditions(or vice versa).While comparisons under controlled environments are challenging for many taxa,assessments of critical thermal limits and vulnerability will always be incomplete unless environmental effects within and across generations are considered,and where the ecological relevance of assays measuring critical limits can be established.

UBM STUDY ON DOUBLE-DIE IRONING PROCESS

The double-die ironing process is studied by means of UBM. The formulas of deformation load.contact stress on die surface, and tensile stress which acts on workpiece is obtained. Taking account of dirnensional accuracy, a new critical condition of limit reduction in cross section area is put forward for the flrst time. The test experiment indicats that results of theoretical analysis well accord with the actual conditions.[0]

Improvement of in situ LA-ICP-MS U-Pb dating method for carbonate minerals and its application in petroleum geology

In situ carbonate U-Pb dating is gaining popularity,and it has great potential for application in petroleum geology.However,the low U content(<10μg/g)and high common Pb content of carbonate minerals,along with the uneven distribution of U and Pb and the lack of matrix-matched reference material make carbonate U-Pb dating inaccurate and less successful,which limits the widespread application in geosciences.This study evaluated the limitations of in situ carbonate U-Pb dating and proposed a method to rationally determine the laser ablation parameters of samples by improving the experimental approach based on the laser ablation sector field inductively coupled plasma mass spectrometry(LA-SF-ICP-MS).By setting a different spot size and laser frequency for the reference material and unknown samples in the same session based on the U content of the sample,the ablation craters of the reference material and unknown samples were given the same depth/width ratio,avoiding systematic offset caused by differences in down-hole element fractionation and reducing the consume of reference material.Depending on the heterogeneous distribution of U and Pb contents in carbonate minerals,the method of grid screening and setting ablation spots during screening were used to quickly select domains with high U and low common Pb,which improves the efficiency of setting laser spots and the success rate of dating,as well as reduces the experimental time and economic cost.The accuracy and success rate of carbonate U-Pb dating were effectively improved by improving the experimental method,and the technique was applied to two carbonate samples with low U and high common Pb contents that were difficult to date by traditional methods.The two samples are the saddle dolomite in the central Sichuan Basin and the calcite cement in the sandstone reservoir of the Cretaceous Qingshuihe Formation in the South Junggar Basin.The robust ages have been obtained,which constrains the timing of the diagenetic and hydrocarbon accumulation process in the studied area.

Comparative assessment of the thermal tolerance of spotted stemborer, Chilo partellus （Lepidoptera： Crambidae） and its larval parasitoid, Cotesia sesamiae （Hymenoptera： Braconidae）

Under stressful thermal environments, insects adjust their behavior and physi- ology to maintain key life-history activities and improve survival. For interacting species, mutual or antagonistic, thermal stress may affect the participants in differing ways, which may then affect the outcome of the ecological relationship. In agroecosystems, this may be the fate of relationships between insect pests and their antagonistic parasitoids un- der acute and chronic thermal variability. Against this background, we investigated the thermal tolerance of different developmental stages of Chilo partellus Swinhoe （Lepi- doptera： Crambidae） and its larval parasitoid, Cotesia sesamiae Cameron （Hymenoptera： Braconidae） using both dynamic and static protocols. When exposed for 2 h to a static temperature, lower lethal temperatures ranged from -9 to 6 ℃, -14 to -2 ℃, and -1 to 4 ℃ while upper lethal temperatures ranged from 37 to 48 ℃, 41 to 49 ℃, and 36 to 39 ℃ for C partellus eggs, larvae, and C. sesamiae adults, respectively. Faster heating rates improved critical thermal maxima （CTmax） in C partellus larvae and adult C partel- lus and C sesamiae. Lower cooling rates improved critical thermal minima （CTmin） in C partellus and C. sesamiae adults while compromising CTmin in C. partellus larvae. The mean supercooling points （SCPs） for C. partellus larvae, pupae, and adults were -11.82 ± 1.78, -10.43 ±1.73 and -15.75 ±2.47, respectively. Heat knock-down time （HKDT） and chill-coma recovery time （CCRT） varied significantly between C partellus larvae and adults. Larvae had higher HKDT than adults, while the latter recovered significantly faster following chill-coma. Current results suggest developmental stage differences in C partellus thermal tolerance （with respect to lethal temperatures and critical thermal limits） and a compromised temperature tolerance of parasitoid C. sesamiae relative to its host, suggesting potential asynchrony between host-parasitoid population phenology and con- sequently biocontrol efficacy under global change. These results have broad implications to biological pest management insect-natural enemy interactions under rapidly changing thermal environments.