Home About us Contact
|
Home About us Contact | ||
|
|
||
Controlled Temperature (controlled + temperature)
Selected AbstractsIncreased temperature sensitivity of net DOC production from ombrotrophic peat due to water table draw-downGLOBAL CHANGE BIOLOGY, Issue 4 2009J. M. CLARK Abstract The production and release of dissolved organic carbon (DOC) from peat soils is thought to be sensitive to changes in climate, specifically changes in temperature and rainfall. However, little is known about the actual rates of net DOC production in response to temperature and water table draw-down, particularly in comparison to carbon dioxide (CO2) fluxes. To explore these relationships, we carried out a laboratory experiment on intact peat soil cores under controlled temperature and water table conditions to determine the impact and interaction of each of these climatic factors on net DOC production. We found a significant interaction (P < 0.001) between temperature, water table draw-down and net DOC production across the whole soil core (0 to ,55 cm depth). This corresponded to an increase in the Q10 (i.e. rise in the rate of net DOC production over a 10 °C range) from 1.84 under high water tables and anaerobic conditions to 3.53 under water table draw-down and aerobic conditions between ,10 and , 40 cm depth. However, increases in net DOC production were only seen after water tables recovered to the surface as secondary changes in soil water chemistry driven by sulphur redox reactions decreased DOC solubility, and therefore DOC concentrations, during periods of water table draw-down. Furthermore, net microbial consumption of DOC was also apparent at , 1 cm depth and was an additional cause of declining DOC concentrations during dry periods. Therefore, although increased temperature and decreased rainfall could have a significant effect on net DOC release from peatlands, these climatic effects could be masked by other factors controlling the biological consumption of DOC in addition to soil water chemistry and DOC solubility. These findings highlight both the sensitivity of DOC release from ombrotrophic peat to episodic changes in water table draw-down, and the need to disentangle complex and interacting controls on DOC dynamics to fully understand the impact of environmental change on this system. [source] The influence of a spring habit gene, Vrn-D1, on heading time in wheatPLANT BREEDING, Issue 2 2001H. Kato Abstract The adaptability of wheat cultivars to environmental conditions is known to be associated with a vernalization requirement, that is, spring/winter habit. To clarify the genetic effect of the spring habit gene, Vrn-D1, on heading time in the field, recombinant inbred lines (RILs) with or without the Vrn-D1 gene were produced from F2 plants of the cross between ,Nanbukomugi' and ,Nishikazekomugi', non-carrier and carrier cultivars of this gene, respectively. Using growth chambers with a controlled temperature and photoperiod, three components of heading time, i.e. vernalization requirement, photoperiodic sensitivity and narrow-sense earliness (earliness per se), were evaluated in each RIL. RILs with the Vrn-D1 gene (E lines) showed greatly reduced vernalization requirements and slightly shorter narrow-sense earliness than RILs without Vrn-D1 (L lines), although no difference in photoperiodic sensitivity was observed between the two groups. RILs were planted at four different sites in Japan and examined for their heading time in the field. E lines headed significantly earlier than L lines at all locations, indicating that the earliness of E lines is stable in various environmental conditions. These results indicated that spring habit caused by Vrn-D1 gene, as well as narrow-sense earliness, was responsible for heading time in the field. [source] A new method to quantify crazing in various environmentsPOLYMER ENGINEERING & SCIENCE, Issue 3 2001Stephen B. Clay A new technique to quantify the rate of change of craze density in stressed transparent polymeric plates of polycarbonate was developed. The samples are placed under a creep load in a controlled temperature and humidity environment, during which the craze density is measured with a reflective imaging system at a defined rate. It has been shown that this unique method for crazy detection and quantification has sufficient repeatability to generate statistically acceptable data, obeying currently used, the method described in the present work is an in-situ, quantitative, non-subjective, direct measurement of craze density. [source] Acrylate terpolymer in fabrication of medicated skin patchesPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 8 2001Vibha S. Mare Abstract An acrylate based pressure sensitive adhesive (PSA) was synthesized to design a drug-in-adhesive (DIA) type transdermal therapeutic system (TTS) for nitroglycerin used in the treatment of angina pectoris. 2-Ethylhexyl acrylate (EHA), methyl methacrylate (MMA) and acrylic acid (AA) were used to synthesize the PSA by free radical solution polymerization. The effects of reaction time, reaction temperature, initiator concentration and solvent on polymerization were studied. The synthesized terpolymer was characterized by 1H-NMR, FT-IR, differential scanning calorimetry (DSC) and gel permeation chromatography (GPC) and also evaluated for intrinsic viscosity, refractive index, peel strength, moisture uptake and skin irritation potential. The PSA was used to develop DIA type patches of nitroglycerin. The patches were cast using solvent evaporation technique and dried at controlled temperature. The patches were evaluated for thickness uniformity, weight variation, peel strength and moisture pick-up. The percent drug content and in vitro drug release was determined by high pressure liquid chromatography (HPLC) method. On the basis of in vitro release profile, patches were selected for in vitro skin permeation studies. The developed formulation TP-1 (K,=,24.892 mcg/cm2/hr) followed zero-order rate kinetics and showed better skin permeation rate in comparison to the marketed TTS (MTTS) (K,=,17.413 mcg/cm2/hr). TP-1 was subjected to stability testing for a period of 1 year according to ICH guidelines. The patches were found to be stable and an expiry date of 2 years was predicted with storage at 25,°C or below. Copyright © 2001 John Wiley & Sons, Ltd. [source] Laboratory investigation of positive streamer discharges from simulated ice hydrometeorsTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 615 2006Danyal Petersen Abstract Positive streamer discharges have been observed from ice crystals grown from the vapour under controlled temperature and air pressure corresponding to the standard atmosphere and also constant air pressure of 850 hPa. Crystals of size comparable to larger precipitation crystals were grown in a vapour diffusion chamber at various temperatures and pressures, and were subject to electric fields using an in situ electrode assembly. Results show that individual positive streamer discharges can occur at temperatures from near freezing down to at least ,38°C when subject to electric fields on the order of 500kV m,1, in contrast to previous reports of continuous positive streamer discharges occurring only at temperatures warmer than ,18°C for pure ice crystals. These results suggest that positive streamer discharges can occur on frozen precipitation particles at high altitudes in thunderclouds, given a sufficiently strong electric field. Such discharges may be a necessary element of the lightning-initiation process. Copyright © 2006 Royal Meteorological Society [source] Effect of aeration in reducing phytotoxicity in anaerobic digestion liquor of swine manureANIMAL SCIENCE JOURNAL, Issue 4 2007Dai HANAJIMA ABSTRACT Numerous reports have accumulated concerning the quality of solid compost. In contrast, there are few for the residue of anaerobic digestion. In this study, the fertilizer value of anaerobic digestion liquor (ADL) was evaluated, and the effect of aeration on the reduction of the phytotoxicity was examined by a germination assay. Low or high aeration (100 or 400 mL/min) was added to 3 L of ADL obtained from a mixture of pig manure and garbage by using 5-L jar fermenters under a controlled temperature of 30°C. During the 14-day aeration period, a high aeration rate improved the germination index (GI) score from 5.7% to nearly 80%, while a low aeration rate did not. Although organic matter decomposition, determined as chemical oxygen demand, did not differ with aeration intensity, remarkable differences were observed in the time course of changes in pH, electric conductivity and ammonium-nitrogen (NH4 -N) and total nitrogen (T-N) content. Among these parameters, the NH4 -N concentration correlated highly with the GI score (r = 0.986). The primary phytotoxic element in ADL was considered to be NH4 -N, and the stripping of ammonia (NH3) by high aeration resulted in the improvement of the GI score. Although the ratio of major nutrients N : P2O5 : K2O (1:0.41:0.94) in ADL was at nearly same level as conventional liquid fertilizer, special attention should be paid to the high concentration of NH3 when drawing up a fertilization plan. [source] Toxicity of chlorine to different sizes of black tiger shrimp (Penaeus monodon) in low-salinity shrimp pond waterAQUACULTURE RESEARCH, Issue 14 2002Husnah Abstract An experiment was conducted, in a dark room with controlled temperature (27.3,28.4 °C), to determine the acute toxicity of chlorine concentration to black tiger shrimp (Penaeus monodon fabicus) of sizes 0.02 g, 2.75 g, 8.47 g and 23.65 g. Toxicity tests on each of these shrimp sizes were run in triplicate in glass jars under static conditions without media renewal. The concentration of active chlorine that killed 50% of the shrimp of each size after 24-h exposure (LC50 -24 h) was used as an indicator of acute toxicity. Chlorine concentrations applied in the shrimp toxicity test ranged from 2.0 to 14.5 mg L,1 in shrimp pond water. As the test water contained total suspended solids of 22.0,85.0 mg L,1 and total ammonia nitrogen of 0.18,0.40 mg L,1, the resultant concentrations of combined residual chlorine ranged from 0.6 to 3.5 mg L,1, which were the effective doses causing shrimp mortality. The test results showed that 24-h LC50 for average shrimp size at 0.02, 2.75, 8.47 and 23.65 g occurred in water containing combined residual chlorine at a concentration of 0.91, 1.39, 1.74 and 1.98 mg L,1, for which the original application doses were 6.96, 2.05 11.50 and 13.34 mg L,1 respectively. [source] Spontaneous Spawning of Captive Red Snapper, Lutjanus campechanus, and Dietary Lipid Effect on Reproductive PerformanceJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 3 2008Nikolaos Papanikos Two experiments addressed the spontaneous spawning of red snapper, Lutjanus campechanus, under controlled temperatures and photoperiods and the effect of broodstock diets supplemented with oils rich in polyunsaturated fatty acids. In Experiment 1, broodfish were fed a standard diet (ST1) and one enriched with menhaden oil (ER1) over a 355-d period. ER1-influenced egg fatty acid profile, however, did not positively influence egg production. Both diets produced highly viable eggs and larvae but results varied within treatments. In Experiment 2, broodfish were fed either a standard diet (ST2) or one supplemented with oils (ER2) rich in docosahexaenoic and arachidonic acid using a 203-d cycle. Both treatments produced eggs but fertilization rates ranged 0,10%. There was no clear influence of the diets on egg fatty acid profiles. These results indicate that red snapper can spawn spontaneously in tanks under controlled environmental conditions and produce viable eggs and larvae when fed diets based on squid, shrimp, and fish. The fatty acid composition of the diets was reflected in the eggs to some degree, but the oil enrichments did not further enhance the reproductive performance and egg quality under the conditions of this study. [source] Infection of onion leaves by Alternaria porri and Stemphylium vesicarium and disease development in controlled environmentsPLANT PATHOLOGY, Issue 3 2000H. Suheri Infection of onion by Alternaria porri and Stemphylium vesicarium was investigated under a range of controlled temperatures (4,25°C) and leaf wetness periods (0,24 h). Conidia of A. porri and S. vesicarium germinated within 2 h when incubated at 4°C. Terminal and intercalary appressoria were produced at similar frequencies at or above 10°C. The maximum number of appressoria was produced after 24 h at 25°C. Penetration of leaves by both pathogens was via the epidermis and stomata, but the frequency of stomatal penetration exceeded that of epidermal penetration. There was a strong correlation (R2 > 90%) between appressorium formation and total penetrations at all temperatures. Infection of onion leaves occurred after 16 h of leaf wetness at 15°C and 8 h of leaf wetness at 10,25°C, and infection increased with increasing leaf wetness duration to 24 h at all temperatures. Interruption of a single or double leaf wetness period by a dry period of 4,24 h had little effect on lesion numbers. Conidia of A. porri and S. vesicarium separately or in mixtures caused similar numbers of lesions. Alternaria porri and S. vesicarium are both potentially important pathogens in winter-grown Allium crops and purple leaf blotch symptoms were considered to be a complex caused by both pathogens. [source] | ||||||||||||||||