Low Amounts Of Water Research Articles

Water enema CT examination of rectum cancer by reduced amount of water

To define whether volume of water, administered during water enema CT (WE-CT) for local staging of rectal cancer, may be reduced without compromising the diagnostic value of the examination. 29 patients with rectum cancer underwent preoperative WE-CT. Contrast-enhanced CT (equilibrium phase) measurements were performed after i.v. injection of smooth muscle relaxant and rectal administration of 400-500 ml lukewarm tap water. Quality of the obtained scans was evaluated and the images were analyzed for depth of tumor invasion. Results of the CT examinations were compared to findings at surgery. Despite reduced dose of water enema, 19/29 examinations were of excellent quality, 6/29 good, and 4/29 poor, but still diagnostic. We achieved sensitivity (90.1), specificity (70.1) and accuracy (86.2) in differentiating tumors confined to the bowel wall from those extending beyond it. Large volume of water enema administered during CT examination of the rectum may cause complaints and increases the risk of complications. Our results prove that using lower amount of water does not impair the quality of examination and accuracy of local staging of rectum carcinomas.

Solvent and substituent effects in solvolyses of benzoyl chlorides. Variation of mechanisms from Grunwald–Winstein correlation analyses with YBnCl scales †

The solvolysis of seven aromatic acid chlorides, namely 2,6-dimethyl- (1), 2-methyl- (2), 4-methoxy- (3), 4-methyl- (4), 4-chloro-(6), 4-nitro- (7), and unsubstituted benzoyl chloride (5), in a variety of solvents was studied. The observation of a linear correlation of log k against solvent ionizing power YBnCl using the single-parameter Grunwald–Winstein equation indicates a limiting SN1 mechanism for the solvolysis of 1. An SN1 mechanism with significant nucleophilic solvent participation was found in the solvolysis of 2–4, based on the apparent splitting of lines in log kvs. YBnCl plots. Different types of non-SN1 reactions are probably involved in the solvolysis of 5–7, and are likely solvent dependent. Hammett-type plots against σ+ constants indicated a linear relationship for 3–6 only in solvents of high water content (60% aqueous methanol, 50% aqueous acetone and 50% aqueous ethanol) or with high ionising power (100% trifluoroethanol and 80% trifluoroethanol–20% ethanol), but for 3–5 in some solvents containing lower amounts of water or trifluoroethanol. Plots of log k in different solvents against ΔEiso for the isodesmic reaction also suggested a solvent dependence of mechanisms. The advantage of using YBnCl rather than a combination of YCl and aromatic ring parameter I in the correlation analysis is discussed.

Enzyme modification of starch granules: in situ reaction of glucoamylase to give complete retention of d-glucose inside the granule

Starch granules have been modified in situ by using a reaction system in which glucoamylase reacts inside starch granules to give conversions of 10–50% d-glucose inside the granule. Waxy maize, maize, and amylomaize-7 starches were converted to the extent of 18.4, 15.0, and 9.4%, respectively, after reaction for 24 h and to 51.0, 33.8, and 24.4%, respectively, after reaction for 288 h. The reaction conditions, of solid granules with a relatively low amount of water and glucoamylase inside the granule, gave 100% retention of d-glucose inside the granule. The amount of d-glucose obtained inside the granule depends on the length of time of the reaction and the type of starch. The action of glucoamylase inside the granule can be terminated by heating at 110−120° C for 20 min. By stopping the reaction at selected periods of time, starch granules were obtained that contained 10–50% (w/w) d-glucose inside the granules.

Gas-Phase Hydrogenolysis of Dimethyl Maleate to 1,4-Butanediol and γ-Butyrolactone over Copper/Zinc Oxide Catalysts

The gas-phase hydrogenolysis of dimethyl maleate has been studied over copper/zinc oxide catalysts at temperatures between 473 and 513 K in the pressure range from 2 to 35 bar. A Cu/ZnO catalyst with a low copper content of 15 mol % was found to be the most active for the conversion of dimethyl maleate. At very low residence times, significant amounts of dimethyl maleate isomerize to dimethyl fumarate. The reaction then proceeds via the saturated ester, dimethyl succinate, until 1,4-butanediol and γ-butyrolactone are formed together with methanol. Furthermore, the chosen catalyst produces low amounts of tetrahydrofuran and water and only traces of undesirable butanol and CO2. It was found that the production of high amounts of 1,4-butanediol in one step is not possible, because the simultaneous presence of diesters and butanediol gives rise to the formation of a polymeric material via transesterification. Therefore, a two-step process including the complete conversion of dimethyl maleate to γ-butyrolactone, carried out at high temperature and moderate pressure, without formation of butanediol followed by the hydrogenation of γ-butyrolactone to 1,4-butanediol at low temperature and high pressure was proposed. It could be shown by systematic investigation of the hydrogenation of γ-butyrolactone that the amount of 1,4-butanediol formed is limited by thermodynamic constraints. The dependence of the equilibrium constant for the reaction between γ-butyrolactone and 1,4-butanediol was determined as a function of temperature and pressure.

Snow Catch and Soil Water Recharge in Standing Sunflower Residue

Sunflower (Helianthus annuus L.) is an economically viable crop for dryland rotations in the central Great Plains. Sunflower's ability to extract large amounts of soil water can depress subsequent crop yields unless significant soil water recharge occurs. The objectives of this study were to measure the effects of differences in standing sunflower stalk height and population on snow deposition and subsequent overwinter soil water recharge. Observations of snow depth and overwinter soil water recharge were made at seven sites near Akron, CO, over three winters. Sunflower stalks were laid flat after harvest, or left standing at approximately 18 or 28 in. Stalk population varied from approximately 10 600 to 26 100/acre. Silhouette factor (stalk height × diameter × population) ranged from 0 to 111 sq in./1600 sq in. Soil types in the study areas were Rago silt loam (fine, smectitic, mesic Pachic Argiustoll) or Weld silt loam (fine, smectitic, mesic Aridic Paleustoll). Increasing stalk height (and silhouette factor) increased snow catch and soil water content during the winter, but amounts of increase varied depending on wind speed and snow amount. With near-average snowfall amounts and number of drifting storms, soil water recharged linearly with increasing silhouette factor, thereby increasing stored soil water by nearly 5 in. where silhouette factor was 80 sq in./1600 sq in. Maintaining standing sunflower residue during the winter and spring following sunflower harvest can provide critically needed soil water recharge by increasing depth of snow deposition. Research Question Sunflower offers central Great Plains growers an opportunity to diversify from the traditional winter wheat-fallow production system. Low soil water amounts after sunflower harvest require soil water recharge. The objectives of this study were to measure the effects of differences in stalk height and population on changes in snow depth and soil water during the winter and spring following sunflower harvest under the typically variable winter precipitation conditions of the central Great Plains. Literature Summary Standing sunflower stalks have been shown to be effective at reducing wind speed near the soil surface. Approximately four snowstorms with significant drifting potential due to snowfall amount and wind speed occur per year in northeast Colorado. These drifting snow storms have the potential to interact with standing sunflower stalks to trap snow. Wheat residue has been shown to trap snow and increase soil water content over winter in Colorado, North Dakota, and Saskatchewan. Snow catch generally increases as wheat stubble height increases. Measurements in sunflower stalks in Saskatchewan and North Dakota showed snow depths ranging from 9 to 15 in., with melted water equivalent ranging from 2.8 to 3.5 in. Study Description Seven sites with sunflower residue near Akron, CO, were observed during the winters of 1992–1993, 1993–1994, and 1994–1995. Sunflower stalks were laid flat after harvest, or left standing at either 17 to 19 in. or 26 to 29 in. Stalk populations varied from 10 600 to 26 100/acre. Snow depths were measured in the plot area following snow events. Soil water content was measured using a neutron probe and time-domain reflectometry. Applied Questions Are standing sunflower stalks effective at increasing snow catch and overwinter soil water content? For drifting storms, standing sunflower stalks can increase snow depth three to 10 times over areas with residues not standing, depending on the wind velocity associated with the snow storm and the silhouette factor of the standing stalks. The increased snow catch can result in increases in overwinter soil water content. For winters with approximately normal winter storm conditions for northeastern Colorado, producers could expect to see overwinter soil water increase by about 4 in. as the silhouette factor increases from 0 to 60 sq in./1600 sq in. (Fig. 1). Recommendations Producers should leave sunflower stalks standing as tall as possible after harvest to potentially increase snow catch and overwinter soil water storage. Figure 1Open in figure viewerPowerPoint Influence of sunflower silhouette factor on overwinter soil water change during three winters.

An Analysis of the Binder Formation in Electrophoretic Deposition

During the electrophoretic deposition of phosphor particles at a cathode, a material forms via electrochemical precipitation which is necessary for adherence of the coating. The chemistry of binder formation was investigated, particularly the effect of water in the bath of isopropanol containing . The type of binder material formed is dependent upon the amount of water in the deposition bath. For very low amounts of water, the binder material is an alkoxide, . For high amounts of water in the bath (>5 vol %), the binder is predominantly a hydroxide, . At intermediate water concentrations, the binder is a mixture of the two compounds.

Efeito da presença das plantas daninhas no microclima da cultura da cevada

Um experimento foi realizado com cevada (Hordeum vulgare L.) em condições de campo, com o objetivo de avaliar , durante um período de estiagem (82 e 89 dia após a emergência da cevada), o microclima formado pela cultura mantida na presença ou ausência de plantas daninhas desde o início do ciclo. Foram avaliados o teor de água do solo, umidade relativa, temperatura, tensão de vapor d'água, déficit de saturação de vapor d'água, potencial água e teor de água do ar nos períodos da s 8: 30 às 9:00, 11:30 às 12:00, 14:30 às 15:00 e 17:30 às 18:00 horas a 0,0m, 0,10m, 0,20m, 0,30m, 0,40m, 0,50m, 0,60m e 0,70m de altura na entrelinha da cultura. A presença das plantas daninhas na cultura durante o período de estiagem contribuiu para reduzir as perdas de água do solo para a atmosfera. Nos três primeiros períodos do dia e nas áreas mais próximas do solo, a cultura mantida no mato os menores valores de temperatura e déficit de saturação de vapor d'água do ar, e os maiores valores de umidade relativa, tensão de vapor d'água, potencial água e teor de água do ar, que proporcionaram redução do consumo de água do solo.

Preparation of a weakly basic ion exchanger by crosslinking starch with epichlorohydrin in the presence of NH 4OH

Crosslinking of starch with epichlorohydrin in the presence of NH 4OH, NaOH and water was studied. The reaction was optimized and the products analysed by solid-state 13C-NMR in the presence of water, acid-base titration and dyebinding measurements. The presence of different types of hydroxypropyl groups was confirmed by NMR, but their linkage to polysaccharide could not be confirmed because of their minor abundance relative to all other CH 2 groups, and because the motion of the sidechains is much greater than the starch component, which remains fairly constant despite the presence of water. Yield of crosslinked, water-insoluble product is increased as a greater amount of NH 4OH and a lower amount of water is used in the reaction. Product yield using water-insoluble starch is higher than with a water-soluble starch. Closed-vessel (pressurized) reaction conditions increases product exchange capacity. Potentiometric titration of products in Cl −-form or in non-ionized form indicated smaller exchange capacity values than expected from product nitrogen contents, reflecting the difficulty in fully protonating the products. Dye binding by the crosslinked-starch exchangers is pH-dependent, with an increased quantity of dye bound at lower pH, which is consistent with the weak-amine nature of the products. Hydrolyzed Remazol Brilliant Red F3B, a trivalent reactive dye, binds less effectively under acidic conditions, on a molar basis, to the starch-based exchangers than does Alizarin Red S, a monovalent mordant dye. Dye-binding capacities are somewhat lower than the total ion-exchange capacities determined by potentiometric titration, suggesting that a portion of the exchange sites are unavailable to the dyes.

Er3+-Doped Silica and Hybrid Organic/Inorganic Silica Gels

The fluorescence properties of Er{sup 3+} in densified sol-gel silica and alkyl-modified silicates are presented. In sol-gel silica, strong infrared ({sup 4}I{sub 13/2} {yields} {sup 4}I{sub 15/2}) emission was observed over a wide range of Er{sup 3+} concentrations. The effect of metal ion co-dopants, which are known to inhibit clustering of Eu{sup 3+} in sol-gel silica, on Er{sup 3+} fluorescence are also considered. The co-dopants La{sup 3+}, Y{sup 3+}, Yb{sup 3+}, and Al{sup 3+} are increasingly more effective at inhibiting Er{sup 3+} clustering and promoting a more uniform spatial distribution of Er{sup 3+} ions. Lifetime studies were also conducted to assess the extent of hydroxyl quenching. Organic/inorganic hybrid silica gels are expected to contain a lower amount of water than simple sol-gel silica gels and should be better hosts for rare earth ions. Er{sup 3+}-doped hybrid organic/inorganic gels were prepared using Si(OC{sub 2}H{sub 5}){sub 4} and Ch{sub 3}Si(OC{sub 2}H{sub 5}){sub 3}, (CH{sub 3}){sub 2}Si(OC{sub 2}H{sub 5}){sub 2}, or C{sub 2}H{sub 5}Si(OC{sub 2}H{sub 5}){sub 3}. Er{sup 3+} fluorescence spectra and lifetime studies of these gels are presented and compared to simple Er{sup 3+}-doped sol-gel silica. The effect of organic modification on Er{sup 3+} clustering and hydroxyl retention are discussed. Er{sup 3+}more » upconversion properties are also discussed.« less

Flexibility of Enzymes Suspended in Organic Solvents Probed by Time-Resolved Fluorescence Anisotropy. Evidence That Enzyme Activity and Enantioselectivity Are Directly Related to Enzyme Flexibility

A time-resolved fluorescence anisotropy study on the molecular flexibility of active-site labeled anthraniloyl-α-chymotrypsin, dansylsubtilisin Carlsberg, and native subtilisin Carlsberg, suspended in organic solvents, is described. The internal rotational mobility of the fluorophore in the nanosecond time range could be separated from rotation of enzyme aggregates and rapid energy transfer processes. The enzymes suspended in dry organic solvents are less flexible than when dissolved in water. The enzyme flexibility increased with increasing hydration level. The results confirm that the increase in enzyme activity observed upon addition of low amounts of extra water is related to an increase in enzyme flexibility. Differences in enantioselectivity of subtilisin Carlsberg in different organic solvents have been correlated with differences in enzyme flexibility. The relationship between the intemal rotational mobility of the fluorophore and the enantioselectivity provides the first experimental evidence that enzyme flexibility and enzyme enantioselectivity are correlated.

Quantitative extraction of pecan oil from small samples with supercritical carbon dioxide

AbstractA procedure to determine total oil content of pecan was developed for samples weighing 500 and 10 mg by supercritical fluid extraction (SFE) with carbon dioxide as the extraction solvent, and chilled hexane as the trapping solvent. Fatty acid methyl esters (FAMEs) were prepared from the total lipid fraction by using either an aliquot (500 mg starting weight) or the entire extract (10 mg starting weight). Total oil content obtained for either sample size with SFE was similar to that obtained with an organic solvent extraction technique. The fatty acid composition for the total lipid fraction of oils extracted with SFE was the same as for oils extracted with organic solvents, and oil composition did not change during SFE. Both oil yield and fatty acid composition were similar to those reported previously for pecan. Samples could be extracted and placed into FAME‐derivatizing reagents in one day, and fatty acid composition of the total lipid fraction could be determined by gas‐liquid chromatography the next day. The procedure, as demonstrated for pecan, should be suitable for other oilseeds, especially those containing low amounts of water.

Enzymic peptide synthesis in microaqueous, solvent‐free systems

Thermolysin-catalyzed (EC 3.4.24.4) and chymotrypsin-catalyzed (EC 3.4.21.1) peptide synthesis reactions were accomplished without any organic solvent in the presence of low amounts of water under sonication and fluidization. The systems used are considered to be microaqueous solvent-free ones. The influence of several reaction parameters, such as time, the amount of enzyme, the amount of water in free form or bound as hydration water, and the N/C component ratio, on the vield of the thermolysin-catalyzed synthesis of Z-Phe-Leu-NH(2) (up to 87% yield) was investigated in a sonicated system. Besides Z-Phe-Leu-NH(2), the tripeptide derivatives Ac-Xaa-Trp-Leu-NH(2), (Xaa = Gly, Ala) were also obtained in good yields of 79 and 71% respectively. In the latter case, no hydrolytic side reactions were observed. Using a fluidized-bed reactor, chymotrypsin- and thermolysin-catalyzed syntheses of N-protected di- and tripeptide amides could be perfromed with yields in the range of 10 to 40%. (c) 1995 John Wiley & Sons, Inc.

Ventilatory Patterns and Respiratory Transpiration in Adult Terrestrial Insects

Although respiratory surfaces constitute a potential site for dehydration in terrestrial insects, only afew studies have addressed the problem of respiratory transpiration in a manner that explicitly separates water loss associated with gas exchange from cuticular and other avenues of water loss. The most promising of these studies are recent investigations conducted on adult insects that release CO₂ intermittently (discontinuous ventilation [DV] cycle). Using either gravimetric techniques or electronic sensors to compare water lost during interburst (spiracles closed or fluttering, cuticular transpiration only) and burst (spiracles open, cuticular and respiratory transpiration) phases of the cycle, investigators have shown that respiratory water loss accounts for only a small percentage (1.9%-13%) of the total water loss at low to moderate temperatures (15° -30° C). The relatively low amount of water lost during the burst phase in lubber grasshoppers as well the timing and duration of discontinuous CO₂ release raises serious questions regarding the presumed water-saving function of the DV cycle.

Grain Yield of Subsurface Microirrigated Corn as Affected by Irrigation Line Spacing

AbstractWithout irrigation, crop yields are usually water‐limited on the acid soils of the southeastern USA. Economically feasible irrigation systems that require less water are needed. As part of a feasibility study of subsurface microirrigation for corn (Zea mays L.) production, the effects of irrigation line spacing and irrigation water amount were investigated in a 5‐yr study at Suffolk, VA. The soil was a Uchee loamy sand (loamy, siliceous, thermic Arenic Hapludult) with inclusions of Emporia loamy sand (fine‐loamy, siliceous, thermic Typic Hapludult). Treatments were three line spacings (0.91, 1.82, and 2.74 in apart, buried 0.38 m below and parallel to the crop row), low and high water amounts (about 41 and 62% of average pan evaporation, respectively), and a nonirrigated control. Nonirrigated grain yields ranged from 3.12 Mg ha−1 (1987) to 9.73 Mg ha−1 (1989). Irrigated grain yields ranged from 8.27 to 12.02 Mg ha−1. Except for 1987 (the driest year), there was no significant difference between the low and high water application amounts. In 1987, corn irrigated with the higher rate yielded 34% more. Grain yields were highest with irrigation lines placed under each row (narrow spacing) and ranged from a low of 8.55 Mg ha−1 (wide spacing) in 1989 to a high of 12.25 Mg ha−1 (narrow spacing) in 1990. Increased amounts of irrigation water were needed with the wider line spacing to obtain corn grain yields comparable with the other two spacings. It is unlikely that the lowered yield or increased irrigation water required with wide line spacing could offset additional installation costs for the narrow spacing. Irrigation lines spaced in alternate corn row middles (1.83 m) or under the third row (2.74 m) are recommended.

A small-angle X-ray scattering study of the absorption of water into the starch granule

Analysis of the shape of the small-angle X-ray scattering (SAXS) intensity profiles obtained from suspensions of wheat starch granules in water gives information on the amount of absorption into the different regions of the granule. At room temperature, less water is absorbed into the granules the higher the starch concentration. At 51°C, the beginning of the gelatinisation region, lower amounts of water are absorbed when the concentration of starch is high and there is less loss of crystalline order. In an excess of water, co-operative melting occurs, whereas, with less water, the absorption is insufficient to destabilise the crystalline order. The beam damage at room temperature is reflected in a slight increase in order, possibly due to rearrangement after chain scission.

Are there different water requirements in different steps of a catalytic cycle? Hydration effects at the E1 and E2 conformers of sarcoplasmic reticulum Ca(2+)-ATPase studied in organic solvents with low amounts of water.

The Ca(2+)-ATPase from sarcoplasmic reticulum was transferred in an active form to a low-water system composed of toluene, phospholipids, and Triton X-100 (TPT). The Ca(2+)-ATPase activity in the TPT system with 4.0% water (by vol. was about 50% of the activity observed in all-aqueous mixtures. Phosphate formation was linear with time up to 20% of ATP hydrolysis and, as expected from an enzyme-catalysed reaction, activity was linear with protein concentration. No ATPase activity was detected in the presence of 3 mM EGTA, indicating that the enzyme retained its Ca2+ dependence in the TPT system. A hyperbolic response to ATP concentration was observed with a Km of 0.15 mM. There was no detectable ATPase activity at water concentrations below 1.5% (by vol.). With 2.0% water, activity became detectable and increased as the water content was progressively raised to 7.0% (by vol.). Higher amounts of water produced unstable emulsions. Enzyme phosphorylation by ATP and dephosphorylation took place in the TPT system. The velocities of both enzyme phosphorylation and dephosphorylation increased with increments in the water content. The enzyme could also be phosphorylated in the TPT system by inorganic phosphate. However, in comparison to ATP, phosphorylation by phosphate took place with significantly lower amounts of water. It is suggested that at low amounts of water, the enzyme is in a relatively rigid conformation and, as the water content is increased, the ATPase acquires more flexibility and, hence, the capacity to carry out catalysis at higher rates. Nevertheless, the release of conformational constraints of the catalytic site of the E2 conformer takes place at water concentrations much lower than those needed for the expression of catalytic activity by the E1 conformer.

EVALUATION OF WATER CONSERVATION POTENTIAL OF NON-TURF GROUNDCOVERS VS. KENTUCKY BLUEGRASS UNDER INCREASING LEVELS OF DROUGHT STRESS.

In June 1991, a two year field study was initiated to examine if three non-turf groundcovers with reputations for using low amounts of water actually use less water than Kentucky bluegrass (KBG). Irrigation treatments were based on percentages of ET (100%, 75%, 50%, 25%, 0%) and calculated by the modified Penman equation. Results from the 1991 season indicate that at the 100% and 75% treatments Potentilla tabernaemontani and Cerastium tomentosum were significantly better than the other species in terms of establishment and vigor but quality declined significantly at rates below 75%. At the 50% rate both KBG and Sedum acre maintained good quality although growth was slow. At the 25% rate, quality of KBG significantly declined while Sedum acre maintained good quality. Quality of Sedum acre declined only slightly at the 0% treatment and would be a good alternative to KBG if water conservation was a high priority in the landscape.

Effects of dietary lactate and propionate on growth and digesta in Arctic charr, Salvelinus alpinus (L.)

Arctic charr, Salvelinus alpinus (L.), were fed commercial diet with or without supplement of Na-salt of lactate and propionate in brackish water (S = 8–10 ‰) at 8°C. Addition of 1% Na-lactate stimulated growth. Growth of fish fed diet enriched with 1% Na-propionate was depressed compared to fish fed the unsupplemented diet. The gut contents from fish fed the Na-lactate diet contained significantly ( P < 0.05) lower amounts of water, energy, lipid, protein and free amino acids. Highest chemical contents were observed when fish were fed on the Na-propionate diet. Triacylglycerols (TAG), present in the diets, underwent quantitative changes during passage through the fish, and lowest amounts were noted in gut contents from fish fed diet supplemented with Na-lactate. Differences were also observed in the fatty acid composition of TAG in gut contents between the rearing groups. Composition of amino acids (g/100 g amino acid) in stomach and gut contents from the rearing groups were similar. It is suggested that addition of Na-lactate to the diet has a diarrhea preventing effect.

Trachoma and water use; a case control study in a Gambian village

Trachoma is prevalent in many arid areas but data assessing the relationship between water use and trachoma are very scarce. This study compared 18 families having one or more active trachoma cases among the children with 16 trachoma-free families in the same village with respect to water use. Potential confounders such as family size, distance to water source, socio-economic indicators, and hygiene behaviour were assessed in the 2 groups. The families with trachoma were found to use significantly less water per person per day for washing children than did the control group ( P = 0·033) with no evidence of confounding by the other measured variables. Low amounts of water for washing were also associated with unclean faces and impetigo in the children. If such a relationship can be substantiated it might provide the basis for effective and cheap interventions against trachoma.

Fluorometric Fiber-Optic Determination of Low Amounts of Water in Ethanol

The acetal formation of 1-pyrenecarboxaldehyde (PCA) in ethanol followed by the hydrolysis of 1-pyrenecarboxaldehyde diethyl acetal results in significant changes in the absorption and fluorescence spectra. This paper describes the fabrication and characterization of a fluorometric fiber-optic sensor with a PVC membrane containing PCA as a probe to water in ethanol