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81.
Pullulan, which is comprised of glucose units, is a simple linear polysaccharide produced by Aureobasidium pullulans. Pullulan has long been used in various applications such as blood plasma substitutes, food additives, adhesive additives, flocculants, and even environmental pollution control agents. Mathematical models of biomass, pullulan, and sucrose profiles during fermentation not only provide information about the kinetic-metabolic nature of pullulan, but also facilitate the control and optimization of pullulan production. In this study, several models were modified and tested in order to describe biomass, pullulan, and sucrose profiles during batch fermentation using a color variant strain of A. pullulans. The results demonstrated that the modified Gompertz model can serve as a universal equation to fit biomass production, pullulan production, and sucrose consumption. Furthermore, validation of this modified Gompertz model indicated that biomass (slope = 1.00, R2 = 0.991), pullulan (slope = 1.10, R2 = 0.991), and sucrose (slope = 0.96, R2 = 0.991) were all predicted accurately. 相似文献
82.
In this article, we report on the biodegradation of soy‐protein‐grafted polyethylene, which was successfully synthesized by a graft copolymerization method with benzoyl peroxide as the radical initiator. The biodegradation behavior of the grafted polyethylene was ascertained by a soil burial test. The weight‐loss percentage was measured as a function of the number of days, and it was observed that the percentage weight loss increased with increasing number of days. To further substantiate the degradation, microanalysis of the soil containing the samples was carried out. An increase in microorganism colonies was observed with increasing number of days. The hydrolysis of the samples taken from the soil after a specified number of days also corroborated the findings and revealed a continuous loss of weight. The effect of the degradation of the grafted samples on the growth of plants (wheat and soybean) was studied, and we observed that the products of degradation were not harmful to the growth of the plants. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
83.
Kuan-Chen ChengAli Demirci Jeffrey M. CatchmarkVirendra M. Puri 《Journal of food engineering》2011,103(2):115-122
Pullulan fermentations by Aureobasidium pullulans with various initial ammonium ion concentrations were evaluated in a 2-L bioreactor. The results demonstrated that A. pullulans produced highest pullulan (23.1 g/L) when the initial ammonium sulfate was 7 at 5 g/L. The purity of produced pullulan was 94.6%. Seven gram per liter of ammonium sulfate produced more biomass due to the higher level of nitrogen source, but the pullulan-degrading enzyme activity was detected after the depletion of sucrose, which reduced pullulan concentration. From the results of fed-batch fermentation, addition of 10 g/L of sucrose suppressed A. pullulans from producing pullulan-degrading enzyme. Additionally, the modified-Gompertz equation demonstrated its generality to fit all pullulan production, biomass production, and sucrose consumption curves at three ammonium sulfate levels. After incorporating the degrading factor, a re-modified-Gompertz equation was obtained that can adequately describe the decrease of pullulan at the late fermentation stage. 相似文献
84.
Varsha D. Phadtare Vinayak G. Parale Gopal K. Kulkarni Hyung-Ho Park Vijaya R. Puri 《Ceramics International》2018,44(7):7515-7523
In the present study, Aurivillius-structured Ba2+ substituted CaBi2Nb2O9 (CBNO) ceramic powder was synthesized by co-precipitation method. The CBNO thick films were delineated by screen printing method on alumina substrates using co-precipitated ceramic powder. The overlay method was adopted to measure the microwave dielectric properties of prepared thick films. Single phase layered perovskite structure of the prepared thick films was confirmed by X-ray Diffraction. The effects of Ba2+ substitution on the surface morphology, bonding, and microwave dielectric properties of thick films were systematically presented. The maximum value of microwave dielectric constant for the CBNO thick films at 11.8 GHz is 15.6 for Ba2+=0.8 substitution. The shift in the stretching vibration modes of the Nb-O bond of NbO6 octahedron in the Raman spectra with a substitution of Ba2+ in CBNO was observed. The substitution of Ba2+ on A-site of CBNO improves the microwave dielectric properties of prepared thick films. This work may provide a new approach to enhance the microwave dielectric performance of Aurivillius-structured ceramic thick films. 相似文献
85.
An ultra‐wideband planar fractal monopole antenna with dual‐notch characteristics is presented in this article. The microstrip fed antenna consists of nested trapezoidal rings and defected ground plane. Measured results show that the proposed antenna operates with a 10 dB return loss bandwidth from 2.2 to 10.8 GHz with notch bands at (2500‐2690) MHz and (3300‐4200) MHz covering LTE 2500, WiMAX and part of C‐band. 相似文献
86.
Deepak Pathania Manita Thakur Vanita Puri Shefali Jasrotia 《Advanced Powder Technology》2018,29(4):915-924
Gelatin-tin (IV) phosphate nanocomposite (GT/TPNC) ion exchanger was synthesized by mixing gelatin gel into the precipitates of tin (IV) phosphate using sol–gel method. GT/TPNC was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The ion exchange capacity of GT/TPNC was reported to be1.44?meq/g. The material was found monofunctional as indicated from pH titration curves. The distribution coefficient of different metal ions such as Zn2+ (42.10), Cd2+ (37.93), Mg2+ (33.33), Cu2+ (33.21), Al3+ (14.28), Pb2+ (6.06), Ni2+ (12.50) and Co2+ (50.0) was studied using GT/TPNC ion exchanger. The distribution studies confirmed the selectivity of GT/TPNC for Co (II). The photocatalytical degradation of MB was found to be 78% within 5 h of solar illumination using GT/TPNC. Some binary separations such as Co2+–Pb2+, Cd2+–Ni2+, Co2+–Mg2+, Mg2+–Zn2+, Pb2+–Zn2+, Cu2+–Al3+, Al3+–Cd2+, Ni2+–Cu2+ were attempted using GT/TPNC ion exchanger. GT/TPNC was explored for the fabrication of ion-sensitive membrane electrode for the determination of Co (II) in the water system. The membrane electrode was found mechanically more stable with quick response time (30?s) and a wide pH working range (4.0–7.0). 相似文献
87.
Huifang Pang Ahmed M. Abdalla Rakesh P. Sahu Yuping Duan Ishwar K. Puri 《Journal of Materials Science》2018,53(24):16288-16302
Noting that the dielectric properties of manganese oxide make it a promising microwave-absorbing material, a low-temperature method to deposit crystalline MnO2 over carbon nanotubes (CNTs) is developed. Adjusting the pH of the precursor solution allows control over the phases and morphologies of the synthesized manganese oxides MnO2 and Mn3O4 that have minimum reflection losses of ??11 dB and ??6 dB, respectively. The synthesized CNT–MnO2 and CNT–Mn3O4 nanocomposites are superior microwave absorbers than simpler physical mixtures of CNTs and manganese oxides, with reflection losses as high as ??19 dB at 9.5 GHz and ??34 dB at 4 GHz, and have wider absorption bands than pure manganese oxides. Coating CNTs with manganese oxide not only increases dielectric and magnetic losses, but also improves the impedance match between free space and the absorber. The addition of CNTs to pure MnO2 and Mn3O4 improves impedance matching by enhancing the relaxation polarization and conductivity losses, magnetic loss, including contributions form eddy current and natural resonance. This facile, low-cost, scalable, high-yield method produces an enhanced microwave-absorbing nanocomposite. 相似文献
88.
Velhal Ninad Kashid P. B. Kulkarni Gopal Kulkarni D. C. Almoalim Hesham S. Alharbi Sulaiman Ali Puri Vijaya Vattikuti S. V. Prabhakar 《Journal of Materials Science: Materials in Electronics》2021,32(8):10240-10254
Journal of Materials Science: Materials in Electronics - Hexaferrites are a class of materials that have practical applications as microwave absorbing materials (MAMs) and radar absorbing materials... 相似文献
89.
Effect of polymer composition on performance properties of maleate-vinyl ether donor-acceptor UV-curable systems 总被引:1,自引:0,他引:1
Neena Ravindran Ankit Vora Dean C. Webster 《Journal of Coatings Technology and Research》2006,3(3):213-219
The effect of unsaturated polyester backbone composition on the properties of donor-acceptor-UV-cured coatings was explored. The polyesters were designed with similar molecular weights and levels of unsaturation, but with otherwise widely varying backbone compositions. UV-curable coatings were formulated with stoichiometric levels of triethylenglycol divinyl ether and a photoinitiator. The resulting coatings had a broad range of properties, which were found to correlate with the properties and compositions of the polyester backbone polymers. A relatively flexible backbone resulted in lower glass transition temperatures (Tg). The polymer Tg was found to influence the conversion of double bonds achieved during UV curing. Reaction kinetics were evaluated for the coating systems and the results confirmed that the Tg of the systems influenced the double bond conversion. Thermal stability and König pendulum hardness were also found to vary with the backbone composition of the constituent polyester. 相似文献
90.
Machine tool chatter is a serious problem which deteriorates surface quality of machined parts and increases tool wear, noise, and even causes tool failure. In the present paper, machine tool chatter has been studied and a stability lobe diagram (SLD) has been developed for a two degrees of freedom system to identify stable and unstable zones using zeroth order approximation method. A dynamic cutting force model has been modeled in tangential and radial directions using regenerative uncut chip thickness. Uncut chip thickness has been modeled using trochoidal path traced by the cutting edge of the tool. Dynamic cutting force coefficients have been determined based on the average force method. Several experiments have been performed at different feed rates and axial depths of cut to determine the dynamic cutting force coefficients and have been used for predicting SLD. Several other experiments have been performed to validate the feasibility and effectiveness of the developed SLD. It is found that the proposed method is quite efficient in predicting the SLD. The cutting forces in stable and unstable cutting zone are in well agreement with the experimental cutting forces. 相似文献