Glucose Water Solution Research Articles

Determination of poorly fluorescent carbamate pesticides in water, bendiocarb and promecarb, using cyclodextrin nanocavities and related media

The effect of native cyclodextrins (α, β, or γCD with six, seven and eight glucose units, respectively), hydroxypropyl-β-cyclodextrin (HPCD), chitosan (CHT) and glucose in water solution or water with n-propylamine (PA) as co-solvent upon the UV–vis and fluorescence properties of poorly fluorescent N-methyl carbamates pesticides (C) as bendiocarb (2,2-dimethyl-1,3-benzodioxol-4-ol methylcarbamate, BC) and promecarb (3-methyl-5-(1-methylethyl)phenol methylcarbame, PC) was examined. Fluorescent enhancement was found for both substrates with all CDs in water or PA-water except from PC with αCD. The addition of CHT increases the fluorescence of BC but decreases the fluorescence of PC, and glucose addition gives in both cases no spectral changes. Host-guest interaction was clearly determined by fluorescence enhancement with βCD and HPCD with a 1:1 stoichiometry for the complexes ( C:CD). The values obtained for the association constants ( K A, M −1) were (6 ± 2) × 10 2 and (2.3 ± 0.3) × 10 2 for BC:βCD and BC:HPCD complexes, respectively. For PC:βCD and PC:HPCD the values of K A were (19 ± 2) × 10 2 and (21 ± 2) × 10 2, respectively. The ratio of the fluorescence quantum yields for the bound and free substrates ( ϕ CCD/ ϕ C) was in the range 1.74–3.8. The limits of detection ( L D, μg mL −1) for the best conditions were (0.57 ± 0.02) for BC with HPCD and (0.091 ± 0.002) for PC with βCD in water. Application to the analysis in pesticide spiked samples of tap water and fruit yields satisfactory apparent recoveries (84–114%), and for the extraction procedure in fruits and a commercial formulation, recoveries were of 81–98% and 104%, respectively. The method is rapid, simple, direct, sensitive and useful for pesticide analysis.

Specific anion effects on the optical rotation of glucoseand serine

Optical activity is directly related to molecular conformation through the anisotropic polarizabilities of molecules and the refractive index of materials. L-amino acids and D-sugars are characteristic essential bioactive molecules. Since molecular recognition and enzyme activity are related to the conformation of substrates, the relevance of optical activity to biological processes is evident. Specific ion, or Hofmeister, effects that occur with electrolytes at moderately high concentrations modify the behavior of interfaces, molecular forces between membranes, of bulk solutions, of enzymes, and even of DNA. Such effects are universal. Here we report a study on the change in optical rotation induced by some sodium salts for the enantiomers of serine and glucose in water solution. The optical rotation is shown to depend on the kind of anion and on the salt concentration. To obtain further insights into the mechanism behind the phenomenon, Fourier transform infrared (FTIR) spectral studies of serine and glucose solutions in electrolytes were also carried out. The results suggest that it is the differences in interactions of anions at specific chemical sites of the solutes that are responsible for the effects. These forces depend strongly on anion polarizability in water. Such specific ion preferential interactions can affect conformation and internal field, and result in significant changes in optical rotation.

Density and viscosity studies of glucose and fructose solutions in aqueous and 0.5 mol dm3 aqueous NH 4Cl

Abstract Densities and viscosities of glucose and fructose solutions in water and in aqueous 0.5 mol dm−3 NH4Cl have been measured at 298.15, 303.15, 308.15 and 313.15 K. From density data, apparent molar volumes at infinite dilution (φ ;°v) and from viscosity data, the B-coefficients are calculated. Glucose and fructose are found to be structure promoters in water as well as in aqueous 0.5 mol dm−3 NH4Cl solutions.

Interfacial characteristics of diglyceride monolayers at the air/aqueous phase interface

The effect of temperature and subphase composition (water and aqueous solutions of ethanol and glucose) on structural characteristics of some diglycerides (distearin, dipalmitin, and diolein) at the air/water interface, were studied. Monolayers of 1,2-distearin were found to be condensed, while 1,3-distearin monolayers were more expanded and unstable. Distearin monolayers (mixture of both isomers at 50% wt/wt) basically showed a liquid-condensed structure until the collapse point. The additivity rule was not fulfilled and the collapse pressure changed with 1,2-distearin molar fraction, which is indicative of the existence of interactions between molecules of both lipids, the mixture being non-ideal. Addition of glucose stabilized the liquid-condensed structure, while ethanol reduced the interval of existence of this phase. Dipalmitin showed solid, liquid-condensed or liquid-expanded structures, as a function of temperature and surface pressure, but the solid phase is predominant. For diolein films, only the liquid-expanded structure was observed.

Hydroxypropyl-beta-cyclodextrin enhanced fluorimetric method for the determination of melatonin and 5-methoxytryptamine.

The effects of native cyclodextrins (alpha, beta or gamma), hydroxypropyl-beta-cyclodextrin, beta-cyclodextrin solubilized in urea, soluble starch and glucose in water solution on the fluorescence behaviour of melatonin (N-acetyl-5-methoxytryptamine) (M) and 5-methoxytryptamine [5-methoxy-3-(2-aminoethyl)indole] (5M) were determined. In addition, the effect of methanol and propanol with and without beta-cyclodextrin or hydroxypropyl-beta-cyclodextrin was assessed. From the fluorescence changes with pH, the values of the pKa for the ground (9.9 +/- 0.2) and the excited state (7.7 +/- 0.2) for 5M were determined. From the fluorescence changes with beta-cyclodextrin or hydroxypropyl-beta-cyclodextrin, the association constants of M, 5MH [5-methoxy-3-(2-ammoniumethyl)indole] and 5M with the two hosts were determined. The values with beta-cyclodextrin were KAssoc5MH = (1.4 +/- 0.4) x 10(2) mol-1 dm3, KAssoc5M = (1.6 +/- 0.1) x 10(2) mol-1 dm3 and KAssocM = (1.1 +/- 0.2) x 10(2) mol-1 dm3, and with hydroxypropyl-beta-cyclodextrin KAssoc5MH = (1.1 +/- 0.3) x 10(2) mol-1 dm3, KAssoc5M = (2.5 +/- 0.1) x 10(2) mol-1 dm3 and KAssocM = (1.51 +/- 0.07) x 10(2) mol-1 dm3. The ratios of the fluorescence quantum yields for the bound and free substrate (phi b/phi f) were in the range 1.15-1.48. The detection limits under the optimum conditions were 0.381 +/- 0.001 ng cm-3 for the complex 5MH-hydroxypropyl-beta-cyclodextrin in water and 0.290 +/- 0.001 ng cm-3 for the complex M-hydroxypropyl-beta-cyclodextrin in water with 5% of methanol. The recovery of melatonin from pharmaceutical preparations was 98-103% with an RSD of 2%. The recovery from rat pineals was also good. The method is direct, simple and accurate.

Non-invasive glucose measurement based on selective near infrared absorption; requirements on instrumentation and spectral range

A tight control of the level of blood glucose is known to reduce the long-term complications of diabetic patients. A non-invasive measurement method suitable for home use would allow a more accurate and frequent control of glucose level, along with reducing the long-term health care costs of diabetic patients and improving their quality of life. In clinical use, the non-invasive method would be suitable for several applications, such as rapid monitoring of glucose levels in emergency rooms [G. Cote, J. Clin. Engrg. 22 (4) (1997) 253–259]. In this work, the potential of near infrared (NIR) spectroscopy as a non-invasive method has been evaluated on the basis of theoretical considerations and measurements on water–glucose solutions and a test person. The partial least squares (PLS) algorithm was used in calibration. The standard deviation of the error of prediction was 0.97 and 1.14 mmol/l for measurements from water–glucose solutions and the test person respectively.

Effects of glucose in drinking water on the changes in whole blood viscosity and plasma osmolality of broiler chickens during high temperature exposure

This study was conducted to elucidate the influence of glucose in drinking water on whole blood viscosity and plasma osmolality of broilers during high temperature exposure. Two groups of birds, which had ad libitum access to either a 4% glucose-water solution (Group G) or tap water (Group W), were exposed simultaneously to 30 C from 0300 h for 12 h each day for 3 d. During the experimental period, Group G birds had greater metabolic energy intake and body weight gain than Group W. Hematocrit and whole blood viscosity decreased significantly at 30 C compared to controls at 20 C in Group W, whereas, in Group G, no changes were found for these two variables. Plasma osmolality also decreased at 30 C compared to 20 C in Group W, whereas no change was noted in this variable in Group G. However, at 20 C, plasma osmolality was significantly higher in Group W than in Group G, but no difference was observed between the two groups at 30 C. Plasma protein concentration decreased during exposure to 30 C in both groups, but the decrease tended to be greater in Group W than in Group G. These results suggest that glucose intake may alleviate the influence of heat stress on whole blood viscosity and plasma osmolality.

Cyclodextrin enhanced fluorimetric method for the determination of tryptamine.

The effect of native cyclodextrins (alpha-, beta- or gamma- with six, seven or eight glucose units, respectively), hydroxypropyl-beta-cyclodextrin, beta-cyclodextrin solubilized in urea, soluble starch and glucose in water solution on the fluorescence behaviour of tryptamine [3-(2-aminoethyl)indole] (T) was determined. In addition, the effect of methanol and propanol with and without beta-cyclodextrin or hydroxypropyl-beta-cyclodextrin was ascertained. From the fluorescence changes with pH and with beta-cyclodextrin or hydroxypropyl-beta-cyclodextrin, the values of the pKa of the ground and excited states and the association constants of T and TH [3-(2-ammoniumethyl)indole] with the two hosts were determined. The values are pKa = 9.5 +/- 0.2 and pKa* = 8.4 +/- 0.2; KAssocTH = (1.6 +/- 0.3) x 10(2) mol-1 dm3 and KAssocT = (2.8 +/- 0.3) x 10(2) mol-1 dm3 with beta-cyclodextrin, KAssocTH = (1.8 +/- 0.5) x 10(2) mol-1 dm3 and KAssocT = (4.9 +/- 0.9) x 10(2) mol-1 dm3 with hydroxypropyl-beta-cyclodextrin. The ratio of the fluorescence quantum yields for the bound and free substrate (phi b/phi f) were in the range 1.25-1.33. The detection limit for the better conditions where the host-guest interactions produce fluorescence enhancement was 0.454 +/- 0.002 ng ml-1 for the complex T-hydroxypropyl-beta-cyclodextrin in water. The method is simpler than others reported previously.

Human red blood cell membrane potential and fluidity in glucose solutions

This study aimed to investigate the membrane potential and fluidity changes of human red blood cells subjected to isotonic glucose solutions. For the control erythrocytes a membrane potential value of -10.1 ± 1.8 mV was obtained, whereas erythrocyte membranes in diabetic cells were hyperpolarized, with a potential of -13.9±2.3 mV. Incubation of both types of red blood cells with increasing glucose concentrations resulted in a substantial hyperpolarization of the cell membranes. Glucose solutions in water had a much stronger effect on membrane potential than glucose dissolved in phosphate-buffered saline. Red blood cell membrane fluidity measurements using the fluorescent label TMA-DPH did not reveal any significant changes upon incubation with glucose.

Catalytic Oxidation of Glucose on Bismuth-Promoted Palladium Catalysts

Water solutions of glucose (1.66 mol liter −1) were oxidized with air at 313 K on palladium catalysts supported on active charcoal. High gluconate yields (99.3%) were obtained in the presence of bismuth-promoted catalysis. Bismuth was deposited via a surface redox reaction on Pd/C catalysts containing 1- to 2-nm Pd particles. A STEM-EDX study showed that bismuth atoms are selectively and homogeneously deposited on the palladium particles. The catalyst can be recycled without loss of activity and selectivity. Bismuth was not leached from the catalyst during reaction and recycling. Bismuth adatoms prevent oxygen poisoning of the palladium surface by acting as a co-catalyst in the oxidative dehydrogenation mechanism. It was determined by calorimetric measurements that oxygen should adsorb preferentially on bismuth rather than on palladium.

Whole body and splanchnic oxygen consumption and blood flow after oral ingestion of fructose or glucose

The contribution of the splanchnic tissues to the initial 2-h rise in whole body energy expenditure after ingestion of glucose or fructose was examined in healthy subjects. Indirect calorimetry and catheter techniques were employed to determine pulmonary gas exchange, cardiac output, splanchnic blood flow, splanchnic oxygen uptake, and blood temperatures before and for 2 h after ingestion of 75 g of either fructose or glucose in water solution or of water only. Fructose ingestion was found to increase total oxygen uptake by an average of 9.5% above basal levels; the corresponding increase for glucose was 8.8% and for water only 2.5%. The respiratory exchange ratio increased from 0.84 in the basal state to 0.97 at 45 min after fructose ingestion and rose gradually after glucose to 0.86 after 120 min. The average 2-h thermic effect, expressed as percent of ingested energy, was 5.0% for fructose and 3.7% for glucose (not significant). Splanchnic oxygen consumption did not increase measurably after ingestion of either fructose or glucose. The arterial concentration of lactate rose, arterial pH fell, and PCO2 remained essentially unchanged after fructose ingestion. Glucose, but not fructose, elicited increases in cardiac output (28%) and splanchnic blood flow (56%). Fructose, but not glucose, increased arterial blood temperature significantly. It is concluded that both fructose and glucose-induced thermogenesis occurs exclusively in extrasplanchnic tissues. Compared with glucose, fructose ingestion is accompanied by a more marked rise in CO2 production, possibly reflecting an increased extrasplanchnic oxidation of lactate and an accumulation of heat in the body.

Y (Grunwald-Winstein) parameters of aqueous solutions of sugars

The kinetics of solvolysis of t-butyl chloride in water-glucose and water-sucrose solutions have been studied. From the data obtained, Y Grunwald-Winstein parameters corresponding to these mixtures have been derived.

A carbon-13 breath test to characterize glucose absorption and utilization in children.

After the administration of a 5% glucose-water solution that contained tracer amounts of the stable nonradioactive isotope 13C, breath samples were collected from five children with congenital glucose-galactose malabsorption and five with severe small bowel villous atrophy and chronic diarrhea. The 13CO2 breath test curves of the children with the congenital malabsorption and chronic diarrhea were compared with each other and with those from three healthy children and four infants with severe malnutrition but no diarrhea. The breath test curves from the children with glucose-galactose malabsorption and from those with diarrhea were significantly different from those of the other two groups, a finding consistent with impairment of glucose absorption. The [13C]glucose breath test clearly identified the children with severe glucose malabsorption. Further studies are required to determine whether less severe cases of carbohydrate malabsorption also can be identified using the parameters described in our study.

The effect of liver denervation on the consumption of various diets by rats

Liver afferents have been proposed to influence food intake control, however, previous studies have shown that chow (pellet) intake is apparently not altered in total liver denervated rats. The present study explored whether total liver denervation could alter the rats' intake of various diets other than chow pellets. Total liver denervations were verified using staining histological and monoamine histofluorescence techniques. The denervated and sham operated rats were given short-term (4–6 days) exposure to four diets: (diet 1, chow plus a 32% w/v sucrose-water solution; diet 2, 1:1 mixture of powdered chow and granular glucose; diet 3, 33% w/w Crisco and powdered chow mixture and diet 4, a 5% w/v glucose-water solution plus chow. Body weight gains were not affected-by either surgery or diet exposure. Daily consumptions of the diets were similar in both groups, nevertheless, there was a trend for the denervated rats to consume slightly more of a high fat diet, which lends support for one hypothesized liver satiety mechanism. Also, the denervated rats consumed less (an average 5 kcal/day) of the 5% glucose solution (one hypothesis tested would predict an increase consumption of glucose by the denervated rats). Thus the liver may play a role, albeit small, through several ill defined mechanism(s) in the regulation of feeding.

Effect of intraperitoneal and intragastric loading with water and isosmotic solutions of saline and glucose on water intake of dehydrated rats

Female rats, dehydrated with food available for 24 hr, lost 6 to 8% of body weight. When allowed access to water, 40 to 60% of the weight deficit was replaced within the first hr. Either intraperitoneal (IP) or intragastric (IG) water loads (3% of body weight) administered just prior to return of water inhibited water intake of dehydrated rats nearly completely during the first hr of access to water. In contrast, similar loads of isotonic saline were much less effective. Even when 0.5 and 1.0 hr elapsed between IP loading (3% of body weight) with isotonic saline and access to water, water intake was not significantly different from that of untreated, dehydrated controls. In contrast, a similar IP load of water at these times completely inhibited water intake. Because of the contrasting effects of similar loads of water and isotonic saline on water intake of dehydrated rats, additional studies were carried out with an isosmotic solution of glucose (5%). IG administration (3% of body weight) of glucose inhibited water intake of dehydrated rats. IP administration (3% of body weight) attenuated the drinking response but did not reduce it to the level observed in dehydrated rats given an IP water load. When isosmotic glucose was administered at 0.5, 1.0, and 2.0 hr prior to allowing access to water, water intake was reduced significantly below that of dehydrated controls and to the same extent regardless of time of administration of the glucose load. This suggests that inhibition of water intake in dehydrated rats can result from either IG or IP loading and is a function of the type of loading solution rather than the extent of stretch of the gastrointestinal tract or peritoneal cavity. These results also suggest that those loading solutions which draw solutes from extracellular fluid into the peritoneal cavity or gastrointestinal tract inhibit water intake of dehydrated rats. Isotonic saline solutions, which fail to do this, are relatively ineffective in reducing water intake of dehydrated rats. In support of this hypothesis, the effectiveness of similar volumes of saline loading solutions in reducing water intake appeared to increase with decreasing concentrations.

Gravitational effects on transmembrane flux: the rayleigh—taylor convective instability

Using a cell with horizontally mounted membranes, volume flux was measured as a function of gravitational geometry. Water was placed on one side of the membrane. The opposite side of the membrane was exposed to either aqueous glucose solutions, with densities greater than water; or aqueous ethanol, less dense than water; or ethanol—glucose—water solutions. In all cases, the osmotic pressure gradient generated volume flux from water to the solution. No mechanical stirring was used. Experiments were performed first with water above the membrane and the solution below it. They were then repeated with water below and the solution above the membrane. In all cases, volume flux was significantly larger when the denser liquid was above the membrane. Mach—Zehnder interferograms were obtained for the interface region of the water—membrane—0.1 M glucose system, Results show directly that boundary layers are substantially larger and more uniform with the lower-density liquid above the membrane than with the opposite geometry. These experimental findings are interpreted in terms of a convective gravitational instability that reduces boundary layer dimensions and increases volume flux. Following Rayleigh—Tavlor analysis of fluid gravitational stability, a concentration-gradient Rayleigh Number is developed and used in a mathematical model for gravitationally sensitive volume flux.

Change of water structure by solvents and polymers

Viscosity measurements have been made of water-solvent and water-polymer solutions in a temperature range of 20–60 centigrades. A medium structure temperatureT0 was calculated from the Vogel-equation. Water has a structure temperature of 140–150 K, its decrease indicates structure breakage, an increase structure promotion. Pyridine, dioxane, dimethylformamide and urea are structure breakers. This is explained by a shift of the equilibrium — bonded water molecules — nonbonded — to the right. Acetone shows hydrophobic bonding in the same concentration range of 0–10 mole % as the normal alcohols. They are quasifree liquids-structure temperature zero-in the pure state. This is explained by hydrogen bridged dimer formation with the exception of tert-butanol. Its 3 methylgroups sterically prevent dimer formation and cause structuring. Adding urea to methanol-water solutions breaks water structure according to urea concentration but extends the hydrophobic bonding maximum over the whole diagram. Glucose-water solutions have a minimum in the structure temperature diagram. Its left side indicates waterstructure breakage, its right side formation of a new structure forced upon water by the sugar. The equilibrium can be formulated: Waterlike bonded-nonbonded-hetero (solvent)-like bonded, Ribose also shows this minimum but after a short range of heterobondedness the structure is completely broken to nonbondedness.

Electrokinetic studies on estrone/aqueous solutions of nonelectrolyte and electrolyte systems

Electroosmotic, streaming current, and streaming potential measurements have been carried out on estrone membrane using water and aqueous solutions of glucose, sucrose, urea, sodium chloride, and barium chloride. The Onsager reciprocity relationship is found to be valid for all the cases studied, even though streaming current varies nonlinearly with applied pressure difference, Δ P, in the case of aqueous solutions of nonelectrolytes. Second-order terms do not appear in the equation for streaming current for aqueous solutions of electrolytes. Electrophoretic mobility of estrone particles of a known size distribution dispersed in water and aqueous solutions of glucose, sucrose, urea, sodium chloride, and barium chloride have also been studied. The results are interpreted from the viewpoint of nonequilibrium thermodynamics. Some comments on the electrical properties of estrone are also made.

Acute diarrheal infections in infants. I. Epidemiology, Treatment, and prospects for immunoprophylaxis.

Epidemiologic differences that appear to be geographic or climatic actually relate more closely to socioeconomics and sanitation. Regardless of etiology, the major management problems are those of dehydration and its sequelae. Progress toward development of antibacterial and antiviral vaccines is discussed. Next month the viral and bacterial agents that cause diarrheal infections will be reviewed.

Absorption of Silicon by Sorghum Plants

Water solutions of aconitic, citric and tartaric acids, which occur in sorghum juice, dissolve silica much more rapidly than does distilled water. A water solution of glucose was also more effective than water but not quite so effective as the acids. The water-acid solutions were much more effective in extracting silica from soil than a water-glucose solution or distilled water. The silica content of sorghum juices studied was considerably higher than the solubility of amorphous silica in water at 25?C. High content of silica in sorghum juice may be due to the organic acids in the juice.