A Microbiological Study of Sudanese Date Wines

Procedures followed in the home fermentations of three date wines were investigated. Two wines, 'sherbote', and‘nabit’prepared from date sirup, are produced by a relatively quick fermentation taking about 36-48 hr. The fermentation of the third wine;‘dakkai', prepared from whole date fruits, is a slow process taking about 96 hr. The samll amounts of spices and sorghum malt used as additives in the preparation of 'sherbote’and‘nabit', respectively, contribute to the inoculum. In‘dakkai’fermentation of the inoculum comes from the natural flora of the data fruit itself. Changes in the production of ethanol, acetic and lactic acids and pH as well as in microbial populations were followed during fermentation of each wine. The most important genera of yeast, acetic and lactic acid bacteria were identified.     

Remec test with vanishing leading array coefficients

Remec's algorithm for finding breakaway points on the root locus suffers from a serious limitation when the first column entry of the first row of any s' group of the Remec array vanishes. In this paper, a remedy for such situations is proposed by rearranging the coefficients of the row in which a zero entry has occurred in the first column of the array. The coefficients of the rearranged Remec table are calculated by the usual Remec algorithm.     

Influence of Water Stress on Cold-Induced Sweetening in Leafy Vegetable, Brassica juncea L.

The occurrence of low temperature sweetening in Brussica juncen L., an apparently chilling-tolerant leafy vegetables, has been investigated in relation to the effect of water stress and postharvest age (i.e. fresh harvest vs previously stored samples). The magnitude of cold-induced sweetening in B. juncea leaves was estimated to vary from 10–145% relative to the corresponding nonchilled samples. Previously stored leaves showed greater tendency to accumulate sugars but was apparently less responsive to cold-induced sweetening than freshly harvested leaves. Water stress synergistically enhanced this low temperature sweetening response; markedly greater and/or faster accumulation of sugars occurred in leaves that were both chilled and stressed. The majority of the total sugar increase was attributable to non-reducing sugars.     

Effect of pH on the Kinetics of Soybean Lipoxygenase-1

The influence of pH on the kinetics of soybean lipoxygenase-1 was examined. Lipoxygenase-1 was stable when preincubated in the pH range from 3.2 to 9.2 but was irreversibly denatured at pH 3.0 and below. Double reciprocal plots for undenatured enzyme in the pH range 5.6 to 9.2 showed that the enzyme obeyed Michaelis-Menten kinetics in this pH range. The Dixon plot (log V_max/K_m vs pH) indicated an active site of the free enzyme to be a histidine residue with a pK of about 7.3.     

Identification of a class of time-variable linear systems via its output covariance function

The main concern of this paper is to determine the state-space representation of a class of linear time-variable, periodic system, such that when excited by stationary white noise it results in a random process with prescribed covariance function. It is shown that by using a proper transformation on the state covariance matrix of the system it is possible to find a new matrix which has periodicity properties and satisfies a periodic matrix Riceati differential equation; therefore, the time interval of interest, on which the matrix Riceati equation must be solved using previous approaches, will collapse into one period.     

Geotechnical forensic investigation of a slope failure on silty clay soil—A case study

Qila Bala Hisar is one of the noteworthy places of Peshawar, Khyber Pakhtunkhwa. The fort was constructed on a filled ground during the 18th century and it was renovated several times by the occupants ever since. Recently, due to an earthquake of magnitude 7.3, the upper part of the south-western wall of the fort collapsed. The collapse of the wall was attributed to the failure of the retained slope. This research was undertaken to characterize the slope material, study causal factors of failure and evaluate remedial strategy. The investigation involved conventional field and laboratory testing and geophysical investigation using electrical resistivity technique to evaluate the nature of stratum. Also, X-ray Diffraction and Scanning Electron Microscopy was used to study the slope material at a molecular level to evaluate the existence of swelling potential. The analysis has shown that excessive seepage of water caused by the poor maintenance of runoff and sewage drains is the causal factor triggered by the seismic event. A remedial strategy involving soil nails, micro piles and improvement of the surface drainage is recommended.     

Application of polyaniline/manganese dioxide composites for degradation of acid blue 25 by hydrogen peroxide in aqueous media

The kinetics of catalytic degradation of acid blue 25 dye (AB-25) by hydrogen peroxide using polyaniline/manganese dioxide (PANI/MnO₂) composites was investigated. To optimize the degradation kinetics of the dye, several parameters have been varied: (i) parameters varied during the preparation of PANI/MnO₂ composites include: aniline concentration, acid concentration, acid type, amount of ??-MnO₂, stirring time and polymerization temperature and (ii) kinetic variables include: [H₂O₂], dye concentration, amount of composite, pH, addition of salt, and UV-light irradiation. The catalytic activity of the composite is obtained when it has (i) high % PANI content, (ii) high degree of crystallinity, and (iii) high doping ratio. The reaction obeyed second-order kinetics with respect to [H₂O₂], attains a maximum, and decreases thereafter. The degradation decreased when the dye concentration increased. Additionally, the effect of salts on the degradation rate was also studied. The rate of reaction decreases with increasing pH of the medium due to (i) the conversion of ES form of PANI into EB form and (ii) protonated form of the dye is more facial to be oxidized than the deprotonated form. Degradation rate was increased in the presence of UV/H₂O₂ compared to H₂O₂ alone. Mechanism was proposed for the catalytic degradation reaction which is in agreement with the experimental data.