Visual simulation of botanical trees based on virtual heliotropism and dormancy break

Realistic image synthesis of botanical trees has many applications. Since the generation of ‘tree skeletons’ having natural visual impressions is essential to realistic image synthesis, various methods of modelling skeletons, especially growth models, have been presented. However, no one has succeeded in simulating natural tree features which appear in a growth process, such as generation of a round tree crown, a weeping bough, an irregular branching pattern, or regeneration of a crown. This paper demonstrates, by showing several simulated examples, that a growth model having the abilities of heliotropism and dormancy break, which produces shapes of trees adapted to changes in the light environment, is effective in the CG simulation of realistic tree skeletons.     

电解氯化系统投入时段的研究

对滨海电厂能够附着、污堵循环水通流系统的主要海生物——藤壶,在相关温度区间的生命指标进行了研究,得出了确定防污设备投入时段的依据,明确了在海水温度低于5℃时可以不需对循环水海生物进行杀生,从而每年可以节约1/3的电能;填补了我国在这一方面理论上的空白,取得了一定的经济效益。     

Chemical Scarification and Ozone in Seed Dormancy Alleviation of Wild and Domesticated Opuntia,Cactaceae

Protocols for seed germination in the Opuntia genus are different and unsuitable for all their species. Dormancy of Opuntia seeds can be modified by the combination of scarification and an oxidizing agent such as O₃, which could induce antioxidant and DNA-repair mechanisms or dormancy-breaking effects in hydrated seeds. The objective of this study was to evaluate the effects that the combination of mechanical and chemical scarification with exposition to sub-lethal O₃ doses have on seed germination and seedling growth of O. streptacantha Lem., O. megacantha Salm-Dyck, and O. ficus-indica (L.) Mill. Our hypothesis was that O₃ favors germination on scarified seeds and that the magnitude of the effect is species-dependent. Water uptake and germination were quantified in seeds every 48 h, until their roots reached a 5-mm length. The results were analyzed with an analysis of variance and multiple means comparisons with the Tukey test. Accelerated water uptake was observed during the first 48 h; the maximum average was 33.5% in all species. The combination of acid scarification and imbibition in the presence of O₃ increased (P ≤ 0. 05) germination (between 17.8 and 44.4%), mainly in O. streptacantha. O₃ increased germination, regardless of the species. O₃ can be used in sublethal doses to increase seed germination and seedling development in Opuntia genus.     

A comparative analysis of the cryo-compression and cryo-adsorption hydrogen storage methods

While conventional low-pressure LH₂ dewars have existed for decades, advanced methods of cryogenic hydrogen storage have recently been developed. These advanced methods are cryo-compression and cryo-adsorption hydrogen storage, which operate best in the temperature range 30–100 K. We present a comparative analysis of both approaches for cryogenic hydrogen storage, examining how pressure and/or sorbent materials are used to effectively increase onboard H₂ density and dormancy. We start by reviewing some basic aspects of LH₂ properties and conventional means of storing it. From there we describe the cryo-compression and cryo-adsorption hydrogen storage methods, and then explore the relationship between them, clarifying the materials science and physics of the two approaches in trying to solve the same hydrogen storage task (∼5–8 kg H₂, typical of light duty vehicles). Assuming that the balance of plant and the available volume for the storage system in the vehicle are identical for both approaches, the comparison focuses on how the respective storage capacities, vessel weight and dormancy vary as a function of temperature, pressure and type of cryo-adsorption material (especially, powder MOF-5 and MIL-101). By performing a comparative analysis, we clarify the science of each approach individually, identify the regimes where the attributes of each can be maximized, elucidate the properties of these systems during refueling, and probe the possible benefits of a combined “hybrid” system with both cryo-adsorption and cryo-compression phenomena operating at the same time. In addition the relationships found between onboard H₂ capacity, pressure vessel and/or sorbent mass and dormancy as a function of rated pressure, type of sorbent material and fueling conditions are useful as general designing guidelines in future engineering efforts using these two hydrogen storage approaches.     

Hydrogen storage potential in MIL-101 at 200 K

Hydrogen adsorption isotherms for MIL-101 metal-organic framework are reported within a wide pressure range for temperatures between 77 and 295 K. Data modeling with the modified Dubinin-Astakhov equation shows a good fitting with the experimental results. The calculated absolute adsorption allowed the evaluation of the total hydrogen storage capacity for high pressure storage tank filled with MIL-101 as sorbent. The results show that the gravimetric and volumetric storage capacities at 198 K and 70 MPa are within the present-day accepted DOE targets, even if the storage capacity is slightly decreased by 3–6% as compared to the tank without sorbent. Moreover, the calculations reveal that the dormancy time is much increased, as compared to a tank without sorbent, exceeding the ultimate DOE target of 14 days. The MIL-101 assisted cold high-pressure hydrogen storage at ∼200 K and 70 MPa, brings about an additional advantage and seems promising for both mobile and stationary applications.     

BARLEY DORMANCY AND FATTY ACID COMPOSITION OF LIPIDS ISOLATED FROM FRESHLY HARVESTED AND STORED KERNELS

The influence of kernel surface lipids on barley dormancy was investigated. Kernels with surface lipids extracted by chloroform:methanol (2:1) germinated nearly as well as Intact kernels subsequent to steeping in either distilled water or a solution of formaldehyde (ca 800 mg/l). Both water-sensitivity and innate dormancy were reduced in intact and surface-lipid extracted kernels stepped in formaldehyde when compared with kernels steeped in distilled water. Differences in fatty acid composition occurred in both surface and total kernel lipids of grain held in storage. However, compositional changes in fatty acids could not be used to predict kernel dormancy since increasing germination properties of kernels during the storage period were influenced by environmental conditions at time of harvest and varietal differences.     

MICROBES AND GRAIN GERMINATION

The germination of grains that had been steeped in solutions/suspensions of antibiotics was improved relative to water-steeped controls. The effect of the antibiotics was most striking for dormant grain that had been steeped for 90 min rather than 60 min. By incubating decorticated grains under different amounts of water it was shown that restriction of air to decorticated dormant grains reduced germination much more than was the case with decorticated, mature grains. Incubating the dishes of grain in oxygen, rather than air, overcame the inhibitory effect of excess water, confirming that it was the restriction of the oxygen supply by the water that checked germination. It was shown that sprays of dilute sulphuric acid favoured grain germination by acting on the outer layers of the grain. When acid-sprayed and untreated samples were decorticated and incubated their germination rates under different test conditions were essentially identical. In contrast gibberellic acid was shown to exert its germination-stimulating effects and sodium hydroxide its inhibitory effects on the internal tissues. By comparing the respiration rates of ground samples of grain (entire and decorticated; untreated and surface-sterilised) it was shown that microbes in the surface layers have substantial oxygen uptake rates. It seems that the competition of these microbes with the grain tissues for oxygen is a major cause of dormancy.