Effect of Glucose on Endo-xylanase and β-xylosidase Production by Fungi Isolated in Indonesia

Xylanases are widely produced by fungi, and the production of polysaccharide-degrading enzymes, in general, are usually subjected to carbon catabolite repression. In this work, the ability of several Indonesian indigenous fungi to produce endo-xylanase and β-xylosidase and their responses to glucose as a repressor were determined. Ten fungi were grown in a liquid medium supplemented with glucose as the repressor (0, 1%, 3%, and 5%), and the endo-xylanase and β-xylosidase productions were assayed. Aspergillus aculeatus FIG1 and A. oryzae KKB4 produced 3.85 and 0.70 U/mL of endo-xylanase, respectively, compared with other strains (0.22 U/mL or less). Trichoderma asperellum PK1J2, T. virens MLT2J2, A. aculeatus FIG1, T. asperellum MLT5J1, A. oryzae KKB4, and T. asperellum MLT3J2 produced 0.021–0.065 U/mL of β-xylosidase, whereas the other strains produced 0.013 U/mL or less of β-xylosidase. Adding 1% glucose to the growth medium can partially repress endo-xylanase production in A. aculeatus FIG1, T. asperellum PK1J2, and T. virens MLT4J1 and completely repress other strains. By adding 1% glucose, strains FIG1, PK1J2, and MLT4J1 suffered almost complete repression of β-xylosidase production, although such strains exhibited partial repression of endo-xylanase production. β-Xylosidase produced by the other strains showed complete repression by adding 1% glucose, except for A. aculeatus FIG1, A. tamarii FNCC 6151, and T. asperellum MLT1J1, which showed partial repression. Therefore, adding 3% glucose to the growth medium can result in complete repression of endo-xylanase and β-xylosidase productions in all strains examined.

Design of a Flexible Microstrip Antenna for BAN Applications

A flexible microstrip antenna is a compact antenna that can be coupled with the skin. However, such antennas require to be coupled with an intermediate matching liquid medium which makes the antenna bulky, complicated, and expensive. Body area network devices are wearable wireless devices/sensors that are used to get the information of a patient’s health in terms of physiological changes irrespective of location. A flexible layer made of Polyethylene is chosen as the substrate and a copper patch is levied upon it. This substrate layer lies in between two adhesive layers (GIL GML 1000).In this paper, flexible antennas are designed and simulated for Body area networks (BANs). The S11 parameter, VSWR value, Gain, and the radiation pattern of the antennas are compared. The polyethylene substrate is highly flexible and lightweight; therefore it would be an ideal material to be used as the substrate of the required antenna.

Heat Exchange of the Cylindrical Liquid Body of a Limited Height with the Environment

The experimental investigations of the intensity of the heat exchange between the internal surface of the thin-wall metal cylinder and the studied liquid medium were carried out in conditions of its cooling (heating), i.e. under nonstationary heat exchange conditions. The existence of the regular thermal mode in the liquid medium surrounded by the thin-wall metal cylinder has been established. Local in time heat loss coefficients were derived using appropriate dimensionless equations for the stationary mode conditions of heat-exchange in a large volume. Heat loss coefficients were determined using regular thermal mode methods and computational-&-experimental heat loss coefficients. The changes in the relative values of the heat loss coefficients were analyzed using the method of regular thermal mode and computational-&-experimental heat loss coefficients. The deviations in the values of given coefficients in time are mainly within ± 10 %. Relative values of the heat loss coefficients deviate within ± 40 % using appropriate dimensionless equations for the conditions of the stationary mode of heat exchange in a large volume. This conclusion is natural because the cooling (heating) process is nonstationary.

An Efficient Method of Pennisetum x Advena ‘Rubrum’ Seedlings Production Using Temporary Immersion Bioreactor and Agar Cultures

The aim of this study was to propose an efficient method of Pennisetum x advena ‘Rubrum’ micropropagation. Agar cultures with MS medium supplemented with BAP in various concentrations (0.5 mg/L-2 mg/L) and a temporary immersion bioreactor system (TIS) with liquid medium MS with an addition of 1 mg/L BAP were used. For rooting ½ MS medium with different auxin combinations (IBA, NAA) and activated charcoal was utilized. The most efficient method turned out to be TIS which produced 36.9 new plants in four weeks. The seedlings were slender in shape, bright green in colour with no signs of hyperhydricity. The most suitable agar medium produced 19.5 new plants in an eight week period. Rooting should be carried on ½ MS supplemented with 0.5 mg/L IBA and 0.5 mg/L NAA with an 84% rooting rate. The addition of activated charcoal inhibited rooting.

Growth, respiratory activity and chlorpyrifos biodegradation in cultures of Azotobacter vinelandii ATCC 12837

This study aimed to evaluate the growth, respiratory activity, and biodegradation of chlorpyrifos in cultures of Azotobacter vinelandii ATCC 12837. A strategy based on the modification of culture media and aeration conditions was carried out to increase the cell concentration of A. vinelandii , in order to favor and determine its tolerance to chlorpyrifos and its degradation ability. The culture in shaken flasks, using sucrose as a carbon source, significantly improved the growth compared to media with mannitol. When the strain was cultivated under oxygen-limited (5.5, 11.25 mmol L- 1 h- 1 ) and no-oxygen-limited conditions (22 mmol L -1 h -1 ), the growth parameters were not affected. In cultures in a liquid medium with chlorpyrifos, the bacteria tolerated a high pesticide concentration (500 ppm) and the growth parameters were improved even under conditions with a reduced carbon source (sucrose 2 g L -1 ). The strain degraded 99.6 % of chlorpyrifos at 60 h of cultivation, in co-metabolism with sucrose; notably, A. vinelandii ATCC 12837 reduced by 50% the initial pesticide concentration in only 6 h (DT 50 ).

Theoretical Basis of Face Contact Pressure Design of Zero-leakage Mechanical Seal

Based on the percolation theory, the critical porosity of zero-leakage at the wetting and non-wetting sealing interface working in liquid medium is first discussed. The influence of end-face frictional heat on end-face friction and wear is then investigated. The design criteria for the face contact pressure of mechanical seals with zero-leakage and long-life operation are established. Afterwards, the face contact pressure range of the mechanical seal working in conventional different liquid medium is calculated, and the influence of different working conditions speed, medium temperature and pressure on the face contact pressure range change is analyzed. Existing studies have shown that mechanical seals can achieve zero-leakage and long-life operation. As for the wettable sealing interface, the minimum face contact pressure, corresponding to the zero-leakage condition, is only related to the morphological parameters of the sealing interface, and has nothing to do with the sealing medium. Under the rotating and stationary rings physical parameters and given working conditions, the face contact pressure range of the sealing medium water and propane propylene is 0.477~1.132 MPa. The diesel sealing medium has a larger face contact pressure range than that of water and propane propylene, which can reach 0.477~2.183 MPa. The working condition speed, medium temperature and medium pressure have an influence on the face contact pressure range, while the influence of the working condition speed is the most significant.

A Mathematical Model for Predicting the Sauter Mean Diameter of Liquid-Medium Ultrasonic Atomizing Nozzle Based on Orthogonal Design

As a new type of atomizing nozzle with superior atomizing performance, the liquid-medium ultrasonic atomization nozzle has been widely applied in the field of spray dust reduction. In this study, in order to establish a mathematical model for predicting the Sauter mean diameter (SMD) of such nozzles, the interaction between the SMD of the nozzle and the three influencing factors, i.e., air pressure, water pressure, and outlet diameter were investigated based on the custom-designed spraying experiment platform and orthogonal design methods. Through range analysis, it was obtained that the three parameters affecting the SMD of the nozzle are in the order of air pressure > water pressure > outlet diameter. On this basis, using the multivariate nonlinear regression method, the mathematical model for predicting the SMD of the nozzle was constructed. Comparison of the experimental results with the predicted values of the SMD of the nozzle by the multivariate nonlinear regression mathematical model, showed strong similarity with an average relative error of only about 5%. Therefore, the established mathematical model in this paper can be used to predict and calculate the droplet size for liquid-medium ultrasonic atomizing nozzles.

On necessity for analytical solution of the Bloch equations for nuclear magnetic resonance signals at condition express control of liquid medium

The necessity of using express analysis methods to control medium condition is substantiated. It has been shown that the method of express control based on the phenomenon of nuclear magnetic resonance is one of the most preferable. It was found that to increase the information about the medium condition state obtained from the recorded NMR signal, it is necessary to use a mathematical model (based on analytical solutions of the Bloch equations). Two approaches are considered that are used to describe the NMR signal in a liquid medium. It is determined that in the classical approach in the system of Bloch equations it is possible to take into account the peculiarities of using radiotechnical methods of signal registration. The direction of the analytical solution of the Bloch equation is proposed. The experimental data are compared with the numerical solution.