Heat and Mass Transfer Measurements for Tray-Fermented Fungal Products

In this study, heat and mass transfer in static tray fermentation, which is widely used in solid-state fermentation (SSF) to produce fungal products, such as enzymes or koji, is investigated. Specifically, kinetic models of transport phenomena in the whole-tray chamber are emphasized. The effects of temperature, moisture, and humidity on microbial growth in large-scale static tray fermentation are essential to scale-up SSF and achieve uniform fermentation. In addition, heat and mass transfer of static tray fermentation of Trichoderma fungi with two tray setups??traditional linen coverings and stacks in a temperature?Chumidity chamber is examined. In both these setups, the following factors of fermentation were measured: air velocity, air temperature, illumination, pH, carbon dioxide (CO₂) concentration, and substrate temperature, and the effects of bed height, moisture of substrate, and relative humidity of air are studied. A thin (1 cm) bed at 28 °C and 95 % relative humidity is found to be optimum. Furthermore, mixing was essential for achieving uniform fermentation of Trichoderma fungi. This study has important applications in large-scale static tray fermentation of fungi.     

Priority setting in maintenance management: a modified multi-attribute approach using analytic hierarchy process

In the current economic climate, budgets for the maintenance of public buildings are unlikely to meet the ever-increasing maintenance needs. Although it is unlikely that this problem can be overcome completely without an injection of further resources, it is possible for government maintenance authorities to improve the situation by ensuring that the best solution in terms of ‘value for money’ is achieved in the planned maintenance programme. A maintenance plan which is based on a rational assessment of priorities and up-to-date knowledge of the condition of the property stock will help to ensure the best use of available resources. Based on the multi-attribute maintenance prioritization model developed by Alan Spedding, Roy Holmes and Qiping Shen at the University of West of England, which is simple in practice and flexible from a management point of view, this paper presents the results of some further research into this area by modifying the original model using an analytical hierarchy process in deciding the weightings of the criteria set out in the prioritization model. This modified model is more quantitative and objective than the original model. The validation of the framework is also discussed.     

Two-step purification strategy for enhanced recovery of recombinant hepatitis B surface antigen from Pichia pastoris

Univariate screening on factors affecting the purification performance of recombinant hepatitis B surface antigen (HBsAg) on ion exchange chromatography (IEC) and size exclusion chromatography (SEC) and the establishment of a two-step purification strategy were performed. Amongst four IEC adsorbents examined, the use of Q Sepharose XL IEC adsorbent under optimized conditions together with optimized SEC purification was able to efficiently purify HBsAg. An established purification strategy comprising the two techniques further demonstrated adaptability for scale-up operations with a final total purification factor (PF) of 94.82 ± 16.20, HBsAg purity of 95.48% and recovery yield of 78.07%.     

Tensile-Strained Germanium CMOS Integration on Silicon

Monolithic integration of tensile-strained Si/ Germanium (Ge)-channel n-MOS and tensile-strained Ge p-MOS with ultrathin (equivalent oxide thickness ~14 Aring) HfO₂ gate dielectric and TaN gate stack on Si substrate is demonstrated. Defect-free Ge layer (279 nm) grown by ultrahigh vacuum chemical-vapor deposition is achieved using a two-step Ge-growth technique coupled with compliant Si/SiGe buffer layers. The epi-Ge layer experiences tensile strain of up to ~0.67% and exhibits a peak hole mobility of 250 cm²/V ldr s which is 100% higher than the universal Si hole mobility. The gate leakage current is two orders of magnitude lower compared to the reported results on Ge bulk.     

CMOS compatible dual metal gate integration with successful Vth adjustment on high-k HfTaON by high-temperature metal intermixing

In this paper, we report for the first time a novel dual metal gate (MG) integration process for gate-first CMOS platform by utilizing the intermixing (InM) of laminated ultra-thin metal layers during high-temperature annealing at 1000 °C. In this process, an ultra-thin (2 nm) TaN film is first deposited on gate dielectric as a buffer layer. Preferable laminated metal stacks for NMOS and PMOS are then formed on a same wafer through a selective wet-etching process in which the gate dielectric is protected by the TaN buffer layer. Dual work function for CMOS can finally be achieved by the intermixing of the laminated metal films during the S/D activation annealing. To demonstrate this process, prototype metal stacks of TaN/Tb/TaN (NMOS) and TaN/Ti/HfN (PMOS) has been integrated on a single wafer, with WF of 4.15 and 4.72 eV achieved, respectively. Threshold voltage (V_th) adjustment and transistor characteristics on high-k HfTaON dielectric are also studied.     

Multicast-based inference of network-internal delay distributions

Packet delay greatly influences the overall performance of network applications. It is therefore important to identify causes and locations of delay performance degradation within a network. Existing techniques, largely based on end-to-end delay measurements of unicast traffic, are well suited to monitor and characterize the behavior of particular end-to-end paths. Within these approaches, however, it is not clear how to apportion the variable component of end-to-end delay as queueing delay at each link along a path. Moreover, there are issues of scalability for large networks. In this paper, we show how end-to-end measurements of multicast traffic can be used to infer the packet delay distribution and utilization on each link of a logical multicast tree. The idea, recently introduced in Caceres et al. (1999), is to exploit the inherent correlation between multicast observations to infer performance of paths between branch points in a tree spanning a multicast source and its receivers. The method does not depend on cooperation from intervening network elements; because of the bandwidth efficiency of multicast traffic, it is suitable for large-scale measurements of both end-to-end and internal network dynamics. We establish desirable statistical properties of the estimator, namely consistency and asymptotic normality. We evaluate the estimator through simulation and observe that it is robust with respect to moderate violations of the underlying model.