Enhancement of 2,3-butanediol production by Klebsiella pneumoniae PTCC 1290: Application of Taguchi methodology for process optimization

2,3-Butanediol production parameter optimization using Klebsiella pneumoniae PTCC 1290 was performed using the design of experiments available in the form of an orthogonal array and a software for automatic design and analysis of the experiments, both based on Taguchi protocol. Optimal levels of physical parameters and key media components namely temperature, pH, inoculum size, agitation, acetic acid and succinic acid were determined. 2,3-Butanediol production obtained from the 18 sets offermentation experiments performed with the selected factors and levels were further processed with Qualitek-4 software at bigger is better as quality character. The optimized conditions showed an enhanced 2,3-butanediol production of 35.8% (from 11.856 to 18.459 g l-1). The optimal combinations of factors obtained from the proposed design of experiments methodology was further validated by conducting fermentation experiments and the obtained results revealed an enhanced 2,3-butanediol production of 25.8%. Taguchi approach of design of experiments resulted in evaluating the main and interaction effects of the factors individually and in combinatio

Propagating transverse waves in soft X-ray coronal jets

Aims. The theoretical model for magnetohydrodynamic (MHD) modes guided by a field-aligned plasma cylinder with a steady flow is adapted to interpret transverse waves observed in solar coronal hot jets, discovered with Hinode/XRT in terms of fast magnetoacoustic kink modes. Methods. Dispersion relations for linear magnetoacoustic perturbations of a plasma jet of constant cross-section surrounded by static magnetised plasma are used to determine the phase and group speeds of guided transverse waves and their relationship with the physical parameters of the jet and the background plasma. The structure of the perturbations in the macroscopic parameters of the plasma inside and outside the jet, and the phase relations between them are also established. Results. We obtained a convenient expansion for the long wave-length limit of the phase and group speeds and have shown that transverse waves observed in soft-X-ray solar coronal jets are adequately described in terms of fast magnetoacoustic kink modes by a magnetic cylinder model, which includes the effect of a steady flow. In the observationally determined range of parameters, the waves are not found to be subject to either the Kelvin-Helmholtz instability or the negative energy wave instability, and hence they are likely to be excited at the source of the jet

On-disk coronal rain

Small and elongated, cool and dense blob-like structures are being reported with high resolution telescopes in physically different regions throughout the solar atmosphere. Their detection and the understanding of their formation, morphology and thermodynamical characteristics can provide important information on their hosting environment, especially concerning the magnetic field, whose understanding constitutes a major problem in solar physics. An example of such blobs is coronal rain, a phenomenon of thermal non- equilibrium observed in active region loops, which consists of cool and dense chromospheric blobs falling along loop-like paths from coronal heights. So far, only off-limb coronal rain has been observed and few reports on the phenomenon exist. In the present work, several datasets of on-disk H{\alpha} observations with the CRisp Imaging SpectroPolarimeter (CRISP) at the Swedish 1-m Solar Telescope (SST) are analyzed. A special family of on-disk blobs is selected for each dataset and a statistical analysis is carried out on their dynamics, morphology and temperatures. All characteristics present distributions which are very similar to reported coronal rain statistics. We discuss possible interpretations considering other similar blob-like structures reported so far and show that a coronal rain interpretation is the most likely one. Their chromospheric nature and the projection effects (which eliminate all direct possibility of height estimation) on one side, and their small sizes, fast dynamics, and especially, their faint character (offering low contrast with the background intensity) on the other side, are found as the main causes for the absence until now of the detection of this on-disk coronal rain counterpart.Comment: 18 pages, 10 figures. Accepted for Solar Physic

Determination of the Optimum Conditions for Production of Chitosan Nanoparticles

Bioedegradable nanoparticles are intensively investigated for their potential applications in drug delivery systems. Being a biocompatible and biodegradable polymer, chitosan holds great promise for use in this area. This investigation was concerned with determination and optimization of the effective parameters involved in the production of chitosan nanoparticles using ionic gelation method. Studied variables were concentration and pH of the chitosan solution, the ratio of chitosan to sodium tripolyphosphate therein and the molecular weight of chitosan. For this purpose, Taguchistatistical method was used for design of experiments in three levels. The size of chitosan nanoparticle was determined using laser light scattering. The experimental results showed that concentration of chitosan solution was the most important parameter and chitosan molecular weight the least effective parameter. The optimum conditions for preparation of nanoparticles were found to be 1 mg/mL chitosan solution with pH=5, chitosan to sodium tripolyphosphate ratio of 3 and chitosan molecular weight of 200,000 daltons. The average nanoparticle size at optimum conditions was found to be about 150 nm

Improvement in Purification Method of a Synthesized Cyclic Dimeric Lactide

Lactide was synthesized by reverse polymerization of low molecular weight poly(lactic acid) with two different molecular weights:1500 and 2500. Two different lactide purification processes such as: recrystallization in ethyl acetate and washing the crude lactide with ether before recrystallization in ethyl acetate were evaluated. It has been demonstrated that increasing the molecular weight of poly(lactic acid) does not influence the production yield, melting point and optical rotation of lactide. The washing of crude lactide with ether and recrystallization in ethyl acetate can be carried out in a short period of time (within 1 day) at a high yield (35%) using less solvent. In contrast, the first purification method gives lower (11%) production yield by using higher amount of solvent at longer time. It is also found that the purification methods do not have any specific effect on the properties of lactide

The Effects of Temperature, Initiator and Stabilizer on Polymer Particle Size in Suspension Polymerization of Styrene

In suspension polymerization, particle size distribution of polymer is the outcome of dynamic equilibrium between the break up and coalescence phenomena. The rates of break up and coalescence and consequently polymerization stability depend on several parameters, the most important of which are type and concentration of stabilizer. In this study, the effects of type and concentration of stabilizer, concentration of initiator and temperature on the average particle size and its distribution in suspension polymerization of styrene were experimentally studied. The results showed that poly-meric stabilizers, polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP), are more effective than tricalcium phosphate (TCP) as an inorganic stabilizer in reducing coalescence and achieving narrower particle size distribution.By increasing the stabilizer concentration, average particle size was reduced, while by increasing the initiator concentration, the average particle size and its distribution increased. Lowering polymerization temperature led to small-er average particle size with its narrower distribution