采用岩层变形预计矿山震动

矿山震动是由于开采活动使得上覆岩层运动造成的 ,因此 ,可以根据岩层的运动变形分析预计矿山震动的大小及其分布。岩体的变形能是由垂直应变和形变组成的 ,而矿震能量释放的大小可由岩体运动的变形能来计算。现场观测的实际矿震能量分布与预计的结果非常吻合 ,说明采用岩层变形预计矿山震动的可能性     

A study of an up- and a down-pumping wide blade hydrofoil impeller: Part I. LDA measurements

A wide blade, high solidity ratio, axial flow hydrofoil impeller has been developed particularly for gas dispersion when used in the upward-pumping mode. It has a low power number so that a relatively low torque is required when using it with a large impeller to tank diameter ratio, a commonly desired aim of retrofitting. As part of the work characterising these impellers, laser Doppler anemometry has been used to study the single phase flow both down- and up-pumping, the latter for the first time. Mean and root-mean-square velocities were measured throughout a fully baffled, flat bottomed cylindrical tank. When down-pumping, the discharge flow was almost axial but when up-pumping, it had a strong radial component. Turbulence energy dissipation rates in the impeller region and the discharge stream when up-pumping were found to be higher than those when down-pumping. In both modes, the impeller was found to have a high circulation efficiency. In Part II, the data presented here are used for obtaining computational fluid dynamic solutions of the flow field.     

Energy policy and the role of bioenergy in Poland

Poland, as many other countries, has ambitions to increase the use of renewable energy sources. In this paper, we review the current status of bioenergy in Poland and make a critical assessment of the prospects for increasing the share of bioenergy in energy supply, including policy implications. Bioenergy use was about 4% (165 PJ) of primary energy use (3900 PJ) and 95% of renewable energy use (174 PJ) in 2003, mainly as firewood in the domestic sector. Targets have been set to increase the contribution of renewable energy to 7.5% in 2010, in accordance with the EU accession treaty, and to 14% in 2020. Bioenergy is expected to be the main contributor to reaching those targets. From a resource perspective, the use of bioenergy could at least double in the near term if straw, forestry residues, wood-waste, energy crops, biogas, and used wood were used for energy purposes. The long-term potential, assuming short rotation forestry on potentially available agricultural land is about one-third, or 1400 PJ, of current total primary energy use. However, in the near term, Poland is lacking fundamental driving forces for increasing the use of bioenergy (e.g., for meeting demand increases, improving supply security, or further reducing sulphur or greenhouse gas emissions). There is yet no coherent policy or strategy for supporting bioenergy. Co-firing with coal in large plants is an interesting option for creating demand and facilitating the development of a market for bioenergy. The renewable electricity quota obligation is likely to promote such co-firing but promising applications of bioenergy are also found in small- and medium-scale applications for heat production. Carbon taxes and, or, other financial support schemes targeted also at the heating sector are necessary in the near term in order to reach the 7.5% target. In addition, there is a need to support the development of supply infrastructure, change certain practices in forestry, coordinate RD&D efforts, and support general capacity building. The greatest challenge for the longer term lies in reforming and restructuring the agricultural sector.     

Selection and experimental evaluation of low-cost porous materials for regenerator applications in thermoacoustic engines

This paper aims at evaluating three selected low-cost porous materials from the point of view of their suitability as regenerator materials in the design of thermoacoustic travelling-wave engines. The materials tested include: a cellular ceramic substrate with regular square channels; steel “scourers”; and stainless steel “wool”. Comparisons are made against a widely used regenerator material: stainless steel woven wire mesh screen. For meaningful comparisons, the materials are selected to have similar hydraulic radii. One set of regenerators was designed around the hydraulic radius of 200 μm. This included the ceramic substrate, steel “scourers”, stainless steel “wool” and stacked wire screens (as a reference). This set was complemented by steel “scourers” and stacked wire screens (as a reference) with hydraulic radii of 120 μm. Therefore six regenerators were produced to carry out the testing. Initial tests were made in a steady air flow to estimate their relative pressure drop due to viscous dissipation. Subsequently, they were installed in a looped-tube travelling-wave thermoacoustic engine to test their relative performance. Testing included the onset temperature difference, the maximum pressure amplitude generated and the acoustic power output as a function of mean pressure between 0 and 10 bar above atmospheric. It appears that the performance of regenerators made out of “scourers” and steel “wool” is much worse than their mesh-screen counterparts of the same hydraulic radius. However cellular ceramics may offer an alternative to traditional regenerator materials to reduce the overall system costs. Detailed discussions are provided.     

Short communication: Bovine leukemia virus infection in adult cows does not interfere with foot-and-mouth disease vaccination

Bovine leukemia virus (BLV) is a widespread infection that can affect innate and adaptive immunity; however, little information exists on how BLV infection affects foot-and-mouth disease virus (FMDV) vaccination programs. Vaccination for FMDV is compulsory in many regions of the world, and vaccine efficacy is monitored by measuring total antibodies against this virus. In a previous study, we observed that BLV-infected heifers produced a lower amount of antibodies in response to FMDV at first vaccination. In this follow-up study, we show that BLV status does not interfere with the total level and avidity of anti-FMDV–specific antibodies induced after repetitive routine vaccination in adult cattle. This is relevant information for the proficiency of vaccine-based FMDV control programs in BLV-endemic regions.     

Recent Developments in Suspension Plasma Sprayed Titanium Oxide and Hydroxyapatite Coatings

The paper aims at reviewing of the recent studies related to the development of suspension plasma sprayed TiO₂ and Ca₅(PO₄)₃OH (hydroxyapatite, HA) coatings as well as their multilayer composites obtained onto stainless steel, titanium and aluminum substrates. The total thickness of the coatings was in the range 10 to 150 μm. The suspensions on the base of distilled water, ethanol and their mixtures were formulated with the use of fine commercial TiO₂ pigment crystallized as rutile and HA milled from commercial spray-dried powder or synthesized from calcium nitrate and ammonium phosphate in an optimized reaction. The powder was crystallized as hydroxyapatite. Pneumatic and peristaltic pump liquid feeders were applied. The injection of suspension to the plasma jet was studied carefully with the use of an atomizer injector or a continuous stream one. The injectors were placed outside or inside of the anode-nozzle of the SG-100 plasma torch. The stream of liquid was tested under angle right or slightly backwards with regard to the torch axis. The sprayed deposits were submitted to the phase analysis by the use of x-ray diffraction. The content of anatase and rutile was calculated in the titanium oxide deposits as well as the content of the decomposition phases in the hydroxyapatite ones. The micro-Raman spectroscopy was used to visualize the area of appearance of some phases. Scratch test enabled to characterize the adhesion of the deposits, their microhardness and friction coefficient. The electric properties including electron emission, impedance spectroscopy, and dielectric properties of some coatings were equally tested.     

In Search of Monocot Phosphodiesterases: Identification of a Calmodulin Stimulated Phosphodiesterase from Brachypodium distachyon

In plants, rapid and reversible biological responses to environmental cues may require complex cellular reprograming. This is enabled by signaling molecules such as the cyclic nucleotide monophosphates (cNMPs) cAMP and cGMP, as well as Ca²⁺. While the roles and synthesis of cAMP and cGMP in plants are increasingly well-characterized, the “off signal” afforded by cNMP-degrading enzymes, the phosphodiesterases (PDEs), is, however, poorly understood, particularly so in monocots. Here, we identified a candidate PDE from the monocot Brachypodium distachyon (BDPDE1) and showed that it can hydrolyze cNMPs to 5′NMPs but with a preference for cAMP over cGMP in vitro. Notably, the PDE activity was significantly enhanced by Ca²⁺ only in the presence of calmodulin (CaM), which interacts with BDPDE1, most likely at a predicted CaM-binding site. Finally, based on our biochemical, mutagenesis and structural analyses, we constructed a comprehensive amino acid consensus sequence extracted from the catalytic centers of annotated and/or experimentally validated PDEs across species to enable a broad application of this search motif for the identification of similar active sites in eukaryotes and prokaryotes.     

Trichoderma viride suppresses fumonisin B1 production by Fusarium moniliforme

Biocontrol activity against Fusarium moniliforme was analyzed for a Trichoderma viride strain isolated from root segments of corn plants grown in Piedmont Georgia. The isolate suppressed radial extension of F. moniliforme colonies during cocultivation on potato dextrose agar and fumonisin B1 (FB1) production during incubation of both fungi on corn kernels. T. viride decreased radial extension of F. moniliforme by 46% after 6 days and by 90% after 14 days. Furthermore, the colony diameter of F. moniliforme was less at 14 days than at 5 days, suggesting that F. moniliforme mycelia were undergoing lysis. FB1 production by F. moniliforme on corn kernels decreased by 85% when both organisms were inoculated the same day onto corn kernels and by 72% when inoculation of T. viride was delayed by 7 days after F. moniliforme inoculation. These results are the first to demonstrate that T. viride can suppress FB1 production by F. moniliforme, thereby functioning to control mycotoxin production. Thus, this isolate may be useful in biological control to inhibit F. moniliforme growth as a preharvest agent to prevent disease during plant development and/or as a postharvest agent during seed storage to suppress FB1 accumulation when kernels are dried inadequately.