Effects of TiO2–UVC photocatalysis and thermal pasteurisation on microbial inactivation and quality characteristics of the Korean rice‐and‐malt drink sikhye

Sikhye is a popular Korean rice‐and‐malt drink. This drink is prepared using a specific traditional process and has short shelf life. Commercial processing using ultra‐high temperature affects characteristic colour and flavour attributes and disturbs the traditional method of sikhye preparation. The objective of this study was to compare the effect of TiO₂–UVC photocatalysis (TUVP) nonthermal processing with heat‐pasteurised and untreated sikhye samples during storage at 4 and 10 °C. TUVP and heat treatments were both sufficient to inhibit regrowth of total aerobic bacteria and coliform during storage. Hunter colour parameter values showed that the colour of sikhye was less affected by TUVP treatment compared to the heat treatment. Higher sensory scores for flavour, taste and overall preference were attained for low‐dosage TUVP‐treated (0.24 J cm^?2) samples than for heat‐treated samples but without a significant difference. TUVP treatment effectively controlled the microbial growth during storage at 4 °C for more than 18 days which was reported a serious microbiological safety issue. In summary, TUVP showed its suitability for commercialisation possibilities of fresh sikhye drink by inactivating the main micro‐organisms and thus increasing significantly its shelf life with minimum impact on quality characteristics.     

A highly dispersed Pt/γ-Al2O3 catalyst prepared via deposition–precipitation method for preferential CO oxidation

Highly dispersed Pt/γ-Al₂O₃ catalysts were prepared by deposition–precipitation (DP) method with precursor solutions of various pH. The pH was controlled from 6.5 to 9.5 with 5 wt% NaOH solution. As the pH of precursor solution increases over pH 7.5, the metal dispersion and surface PtO_x species decrease and the Pt particle size increases. PrOx test was carried out with a space velocity of 60,000 mL/h g_cat in temperature ranges from 100 to 200 °C. The [O₂]/[CO] ratio was adjusted between 1 and 2 and the effect of H₂O and CO₂ was examined at [O₂]/[CO] = 2. It is interesting that the CO conversion has good agreement with the Pt metal dispersion. In addition, highly dispersed Pt/γ-Al₂O₃ catalyst prepared by DP with pH 7.5 exhibited good catalytic activity below 150 °C in PrOx due to the improvement of the metal dispersion and reducibility of surface PtO_x species at low temperatures compared with the catalyst prepared by impregnation method.     

Performance analysis of a packet-switched synchronous voice/datatransmission system

The queuing behavior of voice and data traffic for a proposed voice/data multiplexing system is investigated. For synchronization of packetized voice in the packet-switched network, the master frame format of time-division multiplexing (TDM) is utilized. This scheme has discrete delay characteristics for packetized voice and provides a simple play-out method for voice signals. The performance of voice and data traffic is investigated by obtaining the cumulative distribution of delay of voice packets and the mean delay time of voice and data packets. The performances of the proposed system and the circuit-switched system are compared to time-assignment speech interpolation (TASI) in terms of the loss probability of voice traffic and the maximum allowable number of input voice channels for a given trunk capacity. The proposed system has been found to be more efficient than the circuit-switched system with TASI for integrating multiple voice channels in a single link. For a given trunk capacity, the system can accommodate about twice the number of input voice channels as the circuit-switched system     

On reducing computational complexity of codebook search in CELPcoding

A computationally efficient codebook search method in code-excited linear prediction is proposed. The method can reduce the computational complexity by almost one half compared to the frequency-domain codebook search method that is currently regarded as the fastest search method, while giving almost the same quality of speech. This reduction is possible as a result of the simultaneous use of frequency-domain search and code vector sparsity     

Contention-based reservation protocols in multiwavelength opticalnetworks with a passive star topology

In a multiwavelength optical network with tunable transceivers, an algorithm to make the transmitter and the receiver tuned to the same wavelength simultaneously is needed. The paper proposes contention-based reservation protocols using a separate control channel for multiwavelength optical networks with a passive star topology. First, they present a protocol which can be used in the network where the ratio of the end-to-end signal propagation delay to the transmission time of a data packet is smaller than 1. Also, for a very high speed network where this ratio is greater than 1, the authors present three protocols according to the variability of the packet length and the buffering of the reservation. To access the control channel, all the proposed protocols use the slotted ALOHA protocol. The authors analyze these protocols with a finite population model and investigate the delay-throughput characteristics     

CELP based mixed-source model for very low bit rate speech coding

A CELP based mixed-source model is described. It uses a mixed excitation which combines a lowpass-filtered adaptive source and a highpass-filtered stochastic source. In addition, one more stochastic source is newly employed for more natural sounding speech. In informal listening tests, the proposed model at 3 kbit/s shows very good performance both in speech quality and intelligibility.<>     

The electronic and magnetic properties of wurtzite Mn∶CdS,Cr∶CdS and Mn∶Cr∶CdS∶ first principles calculations

In this article, density functional theory (DFT) based on generalized gradient approximation (GGA) and GGA+U, U is Hubbard term, is used to study the electronic properties of CdS doped with different dopants (Cr, Mn). The calculations are carried out for Mn-doped CdS, Cr-doped CdS, and co-doping of Mn/Cr in CdS simultaneously. It is found that hopping of electrons is possible with Cr:CdS and Mn:Cr:CdS while Mn:CdS does not allow the hopping of electrons. Moreover, double exchange interactions are observed in Cr:CdS and d-d super-exchange interactions are observed in Mn:CdS. Now the problem becomes interesting when one magnetic ion (Cr) supporting double exchange interactions and another ion (Mn) supporting d-d super-exchange interactions are doped simultaneously in the same system (CdS). The co-doped CdS is more stable even at high Curie temperature due to p-d double exchange interactions and d-d super exchange interactions. Furthermore, the Cr-3d and Mn-3d states present in-between the band gap are responsible for inner shell transitions and hence for optical properties. Therefore, the co-doped system is taken into account to enhance its applications in the field of spintronic and magneto-optical devices.