Form In Dilute Solution Research Articles

Mathematical Modeling for the Regenerator of Liquid Desiccant Air-Conditioning System

T his paper presents mathematical model for regenerator of liquid desiccant air conditioning system. Regression analysis was used to get the relation between enthalpy and humidity ratio. Performance of regenerator is highly affected by varying the flow direction between air & desiccant thus to get proper regeneration results counter-flow configuration is considered. Previous studies show better regeneration results for counter-flow direction of air to desiccant. Validation is done by comparing results of present study the experimental results of previous studies and comparison was found to be quite satisfactory. Based on above mathematical model performance of regenerator was analyzed. The purpose of this research was regeneration of liquid desiccant from its dilute-solution form to strong-solution.

Number-average molecular mass determination of polymeric material by pyrolysis–gas chromatography

The number-average molecular mass of a polymeric material has been determined by pyrolysis–gas chromatography (Py–GC) via end-group analysis. The major advantage of this technique is that no sample preparation is required. The sample is not required to be in the dilute solution form, and the amount of sample needed is approximately 0.5 mg. Phenyl group-terminated polybutadiene systems have been studied as an example. The application of Py–GC to obtain the end-group concentration, the number-average molecular mass and the limitations of this method are discussed in detail. The success of this development elevates the role of Py–GC as an important technique for end-group analysis for the determination of number-average molecular mass.

A field-study of leaching and degradation of nine pesticides in a sandy soil

A field study was conducted on a coastal sandy soil (Karrakata sand) of Western Australia from July to December 1990, to measure the leaching and degradation rates of chlorpyriphos, chlorthal dimethyl, fenamiphos, linuron, metalaxyl, metribuzin, prometryne, propyzamide and simazine. Commercial grade products were sprayed in dilute solution form at recommended rates to the surface of held plots. Irrigation was applied daily which together with rainfall gave effective rainfall equivalent to at least 120% of potential evaporation. Pesticide residue concentrations in soil samples taken at 5 cm increments down to 50 cm, at different days after application, were determined by high performance liquid chromatography (HPLC). Mean leaching depths (MLDs) were calculated by weighting the percentage residues remaining at different depths in the soil profile. The MLDs for the 5 month period followed the order: chlorpyriphos and chlorthal dimethyl (<5 cm) < linuron and simazine (6) < propyzamide (8) and prometryne (9) < metribuzin (12) < metalaxyl (18) < fenamiphos and metabolites (28). This generally corresponded inversely with the sorption coefficients (K-oc). The degradation rates (i.e. decreases with time of total residue concentration in the sampled profile) could mostly be described by first-order regressions (R(2) = 0.59-0.95). Calculated half-lives showed the order: metribuzin (27 days), simazine (28) < fenamiphos (43), chlorthal dimethyl (45) < prometryne (58), propyzamide (59) < metalaxyl (70) < chlorpyriphos (81) < fenamiphos plus metabolites (98) < linuron (219). The potential for causing ground water contamination, as indicated by the ratio of half-life to Koc followed the order: chlorthal dimethyl, chlorpyriphos < metribuzin, prometryne < simazine, propyzamide < linuron < metalaxyl < fenamiphos and metabolites.

The effect of succinylation and acylation on the physicochemical properties of αs1-casein B

1. 1.|The effect of succinylation and acylation on the association and conformation of α s1-casein B has been studied by ultracentrifugation, optical rotatory dispersion (ORD) and nuclear magnetic resonance (NMR) spectroscopy. 2. 2.|Succinylation prevented the association of α s1-casein B due to the additional negative charge introduced. 3. 3.|Acetyl α s1-casein formed an associating system similar to that of the unmodified protein. n-Hexanoyl, n-octanoyl and n-decanoyl derivatives associated strongly with increasing protein concentration and remained in an aggregated form in dilute solution. Propionyl and n-butyryl α s1-caseins behaved in a fashion intermediate between the acetyl and n-hexanoyl derivatives. 4. 4.|The size of the aggregates produced by the acyl derivatives formed a series similar to that found with corresponding derivatives of β-casein A, with a maximum at the n-hexanoyl derivative. This was attributed to enhanced hydrophobic bonding with increasing n-alkyl chain length and to structural differences in the organisation of the associating units. 5. 5.|ORD studies showed small differences in secondary structure between derivatives. NMR spectra of derivatives containing long n-alkyl chains revealed side-chain interactions which were not present in the native molecule.

Dielectric relaxation in three chlorine substituted anilines

The complex dielectric permittivity of ortho-, meta-, and para-chloroaniline has been measured at various temperatures at the wavelengths of 10, 3, 2, and 1 cm. For the first two compounds the measurements have been made in pure liquid from as well as in solutions in carbon tetrachloride at various concentrations. p-Chloroaniline has been measured only in dilute solution form. The results have been analyzed in terms of two relaxation times, attributed to the rotation of the entire molecule and to the inversion of the NH2 group. Evidence for the self association of the molecules through weak hydrogen bonding has been indicated.

Viscosity-structure relationship for phosphorous, phosphoric, phosphorothionic, and boric esters

1. The specific viscosities have been determined of dilute solutions in benzene and in carbon tetrachloride of phosphorous and boric esters having long hydrocarbon radicals (from octyl to decyl. Comparison of the values found for ηsp (1.4%) and Zη with those calculated indicates that the molecules of these esters are in the extended form in dilute solution, which is in agreement with parachor data. 2. The specific viscosities have been determined of dilute solutions in benzene and in carbon tetrachloride ] of phosphoric and phosphorotionic esters having hexyl and octyl radicals. Comparison of the values found for ηsp (1.4%) and Zη with those calculated indicates that the molecules of phosphoric and phosphorothionic esters are in the extended form in dilute solution which is not in agreement with conclusions based on a study of the parachors of these esters. 3. When a comparison is made of the found and calculated values of ηsp (1.4%) and Zη for macrocyclic compounds having rings of 15–34 members for which viscosity, data are available in the literature, it is found that the viscosity values found are closer to those calculated for the total number of members in the ring than to those calculated, following Staudinger's views, for a half of that number. 4. Cyclic esters of triethylene glycol with succinic, adipic, and sebacic acids have been synthesized, and viscosity measurements have been made on their dilute solutions. The values found for ηsp (1,4%) and Zη are greater than those calculated for the total number of members in the ring, 5. Our results show that further investigation is required into the question of what measurements of viscosity tell us concerning molecules of branched structure and molecules having branched rings, and they show that further investigation. is required also into the nature of Gibling's corrections for parallelism in the determination of molecular structure by the parachor method.

Chlorocruorin: A pigment allied to hœmoglobin

The name chlorocruorin was given by Ray Lankester (1867) to a pigment dissolved in the blood plasma of Sabellid, Serpulid and Chlorhæmid polychæte worms. Lankester showed that chlorocruorin is related to hæmoglobin, since he obtained a hæmochromogen from it. The pigment is burgundy-red when in concentrated solution, green when dilute. It will be shown below that while chlorocruorin is constructed on the same plan as hæmoglobin, the differences between the two are very much greater than the differences between specific hæmoglobins. Chlorocruorin exists in an oxidised and a reduced state which are of almost the same colour. The reduced form in dilute solution is a slightly yellower green than the oxidised. The oxidised differs, however, spectroscopically from the reduced form in the same manner as oxyhæmoglobin differs from hæmoglobin. Oxychlorocruorin has two bands in the red-green part of the visible spectrum and reduced chlorocruorin one broader one. These bands are situated to the red of the corresponding hæmoglobin bands. Chlorocruorin like hæmoglobin, can act as a peroxidase (Lankester, 1870).