Efficient production of pullulan by Aureobasidium pullulans grown on mixtures of potato starch hydrolysate and sucrose

AbstractPullulan is a natural exopolysaccharide with many useful characteristics. However, pullulan is more costly than other exopolysaccharides, which limits its effective application. The purpose of this study was to adopt a novel mixed-sugar strategy for maximizing pullulan production, mainly using potato starch hydrolysate as a low-cost substrate for liquid-state fermentation by Aureobasidium pullulans. Based on fermentation kinetics evaluation of pullulan production by A. pullulans 201253, the pullulan production rate of A. pullulans with mixtures of potato starch hydrolysate and sucrose (potato starch hydrolysate:sucrose=80:20) was 0.212h−1, which was significantly higher than those of potato starch hydrolysate alone (0.146h−1) and mixtures of potato starch hydrolysate, glucose, and fructose (potato starch hydrolysate:glucose:fructose=80:10:10, 0.166h−1) with 100gL−1 total carbon source. The results suggest that mixtures of potato starch hydrolysate and sucrose could promote pullulan synthesis and possibly that a small amount of sucrose stimulated the enzyme responsible for pullulan synthesis and promoted effective potato starch hydrolysate conversion effectively. Thus, mixed sugars in potato starch hydrolysate and sucrose fermentation might be a promising alternative for the economical production of pullulan

Numerical Simulation Analysis of Water Injection Seepage Law in Micro Porous Structure of Coal

In this paper, a nano Voxel X-ray 3D microscope is used to scan the long flame coal samples and to reconstruct the 3D pore structure by the use of microscopic computed tomography. With image segmentation technique, a model of micro-pore structure of coal is obtained from the reconstructed coal. With different planes selected as seepage inlets, a numerical simulation of low-pressure water seepage is conducted. Studies show that water pressure gradually decreases along the direction of water seepage and reaches the maximum at the pore-pipes with good connectivity near the inlet. Due to the difference between the structure and development direction of pores in the three dimensions, there is an optimal seepage outlet that is most appropriately corresponding to each seepage inlet. When different planes are selected as seepage inlets, the velocity of each seepage outlet is positively correlated with the seepage mass flow rate at the outlet

The first symbiotic stars from the LAMOST survey

Symbiotic stars are interacting binary systems with the longest orbital periods. They are typically formed by a white dwarf, a red giant and a nebula. These objects are natural astrophysical laboratories for studying the evolution of binaries. Current estimates of the population of Milky Way symbiotic stars vary from 3000 up to 400000. However, the current census is less than 300. The Large sky Area Multi-Object fiber Spectroscopic Telescope (LAMOST) survey can obtain hundreds of thousands of stellar spectra per year, providing a good opportunity to search for new symbiotic stars. In this work we detect 4 of such binaries among 4,147,802 spectra released by the LAMOST, of which two are new identifications. The first is LAMOST J12280490-014825.7, considered to be an S-type halo symbiotic star. The second is LAMOST J202629.80+423652.0, a D-type symbiotic star

Research on vibro-acoustic characteristics of the aluminum motor shell based on GA-BP neural network and boundary element method

Firstly, the paper established a finite element model for a steel motor shell and computed related modals, vibration velocities, stress and strain respectively. Computational results show that the flange and end shield of the motor shell had the maximum vibration velocities and strain because these locations lacked the reinforcing ribs, while the maximum stress was mainly at joints between different structures. Secondly, the steel material was replaced by the aluminum alloy. Mechanical parameters of the motor shell were recomputed and compared with those of the steel structure. Results show that modal frequency on each order increased, which is good for avoiding the structural resonance. In addition, the maximum stress of the structure decreased by 4.4 MPa, and the maximum strain decreased by 0.27 mm, which could effectively improve the fatigue characteristics of the motor shell under long-term excitation. Then, the boundary element method was used to compute radiation noises of the motor shell in far field, where the radiation noise presented an obvious directivity. Finally, the paper proposed a GA-BP neural network model to predict the radiation noise of the motor and compared the prediction results with the boundary element. In the whole analyzed frequency band, the maximum difference between the neural network prediction and the real values did not exceed 5 dB, indicating that it is feasible to predict radiation noises of the motor by the neural network. Additionally, experiments were also conducted and compared with two kinds of numerical methods. Methods proposed in this paper provide some references for realizing the rapid noise reduction and light weight of motors

1-Chloro­methyl-1H-1,2,3-benzotriazole

In the title compound, C7H6ClN3, the benzotriazole ring is essentially planar with a maximum deviation of 0.0110 (15)Å, and makes a dihedral angle of 0.46 (8)° with the benzene ring. In the crystal, mol­ecules are linked through inter­molecular C—H⋯N hydrogen bonds, forming chains along the c axis

The Hidden Nematic Fluctuations in the Triclinic (Ca0.85La0.15)10(Pt3As8)(Fe2As2)5 Superconductor Revealed by Ultrafast Optical Spectroscopy

We reported the quasiparticle relaxation dynamics of an optimally doped triclinic iron-based superconductor (Ca$_{0.85}$La$_{0.15}$)$_{10}$(Pt$_3$As$_8$)(Fe$_2$As$_2$)$_5$ with bulk $T_c$ = 30 K using polarized ultrafast optical pump-probe spectroscopy. Our results reveal anisotropic transient reflectivity induced by nematic fluctuations develops below $T_{nem}$ $\approx$ 120 K and persists in the superconducting states. Measurements under high pump fluence reveal three distinct, coherent phonon modes at frequencies of 1.6, 3.5, and 4.7 THz, corresponding to $A_{1g}(1)$, $E_g$, and $A_{1g}(2)$ modes, respectively. The high-frequency $A_{1g}(2)$ mode corresponds to the $c$-axis polarized vibrations of FeAs planes with a nominal electron-phonon coupling constant $\lambda _{A_{1g}(2)}$ $\approx$ 0.139 $\pm$ 0.02. Our findings suggest that the superconductivity and nematic state are compatible but competitive at low temperatures, and the $A_{1g}$ phonons play an important role in the formation of Cooper pairs in (Ca$_{0.85}$La$_{0.15}$)$_{10}$(Pt$_3$As$_8$)(Fe$_2$As$_2$)$_5$.Comment: 6 pages, 3 figures and Supplemental Material