Plantwide operability assessment for nonlinear processes using a microscopic level network analysis

The increase of raw material and energy costs has caused a shift in process design philosophy leading to more complex chemical plants utilising heat integration and material recycles. This warrants plantwide dynamic operability analysis in the process design stage. In our previous work, a networked plantwide operability analysis approach was developed, where the plantwide process is viewed as a network of process units connected via mass and energy flow. Such an analysis is based on the dissipativity of each process unit and the topology of the process network. However, to determine the dissipativity of multivariable nonlinear process units is often extremely difficult. In this work, we take the network approach to a microscopic level and treat each nonlinear multivariable process unit as a network of individual (single state) mass and energy balances (sub-systems). The plantwide process is then viewed as a network of such sub-systems rather than physical process units. The dissipativity of these simple sub-systems can often be determined more easily in comparison to that of multivariable sub-systems. The dissipativity property (in terms of supply rate) of the entire nonlinear process can be parametrised by the dissipativity of individual sub-systems, leading to a cluster of supply rates. The operability of the plantwide nonlinear process can then be determined based on the above parametrised dissipativity which can be much less conservative than existing nonlinear analysis. The effects of interactions caused by the interconnections are considered explicitly based on the network topology. The stability and stabilisability analysis problem is then converted into a feasibility problem with linear matrix inequalities which can be solved numerically. The application of the proposed approach requires successful determination of the dissipativity of nonlinear sub-systems.     

Molecular typing shows a high level of HLA class I incompatibility in serologically well matched donor/patient pairs: implications for unrelated bone marrow donor selection

In comparison with HLA-matched sibling bone marrow transplants, unrelated donor transplants are associated with increased graft-versus-host disease and graft failure. This is likely in part due to HLA incompatibilities not identified by current matching strategies. High resolution DNA-based typing methods for HLA class II loci have improved donor selection and treatment outcome in unrelated donor bone marrow transplantation. By using DNA-based typing methods for HLA-A and -B on a cohort of 100 potential bone marrow donor/patient pairs, we find that serological typing for HLA class I is limited in its ability to identify incompatibilities in unrelated pairs. Furthermore, the incompatibilities identified are associated with the presence at high frequency of alloreactive cytotoxic T-lymphocyte precursors. DNA typing also indicates that HLA-C mismatches are common in HLA-A and -B serologically matched pairs. Such mismatches appear to be significantly less immunogenic with respect to cytotoxic T-lymphocyte recognition, but are expected to influence natural killer cell activity. Thus, improved resolution of HLA class I shows many previously undisclosed mismatches that appear to be immunologically functional. Use of high resolution typing methods in routine matching is expected to improve unrelated donor selection and transplant outcome.     

Measurement of cytotoxic T lymphocyte precursor frequencies reveals cryptic HLA class I mismatches in the context of unrelated donor bone marrow transplantation

OBJECTIVE: Type 2 diabetes is a slowly progressive disease, in which the gradual deterioration of glucose tolerance is associated with the progressive decrease in beta-cell function. Hyperglycemia per se has deleterious effects on both beta-cell function and insulin action, which are partially reversible by the short-term control of blood glucose levels. We hypothesized that the induction of euglycemia, using intensive insulin therapy at the time of clinical diagnosis, could lead to a significant improvement in insulin secretion and action and thus alter the clinical course of the disease. RESEARCH DESIGN AND METHODS: Thirteen newly diagnosed diet-unresponsive type 2 diabetic patients were treated with continuous subcutaneous insulin infusion (CSII) for 2 weeks and followed longitudinally while being treated with diet alone. RESULTS: Four patients were considered therapeutic failures since CSII failed to induce euglycemia (n = 1) or glucose control deteriorated within 6 months after CSII (n = 3). The remaining nine patients were maintained on diet alone with adequate control from 9 to > 50 months (median +/- SE, 26 +/- 4.8 months). In five patients, glycemic control deteriorated after 9-36 months, but a repeat 2-week CSII treatment reestablished control in four patients. One of these patients underwent a third CSII treatment 13 months later. At the time this article was written, six patients of the initial group were still controlled without medication 16-59 months (median +/- SE, 45.5 +/- 6.6 months) after the initiation of treatment. Body weight remained unchanged in all patients. CONCLUSIONS: These findings suggest that in a significant proportion of type 2 diabetic patients who fail to respond to dietary measures, short-term intensive insulin treatment can effectively establish responsiveness, allowing long-term glycemic control without medication. Further studies are required to establish whether simpler treatment regimens could be equally effective. If the hypothesis offered here finds support, present approaches to the management of newly diagnosed type 2 diabetes may need to be revised.     

Protein-protein and protein-DNA interactions in the type I restriction endonuclease R.EcoR124I

The type I restriction-modification system EcoR124I recognizes and binds to the split DNA recognition sequence 5'-GAAN(6)RTCG-3'. The methyltransferase, consisting of HsdM and HsdS subunits with the composition M2S, can interact with one or more subunits of the HsdR subunit to form the endonuclease. The interaction of the methyltransferase with HsdR has been investigated by surface plasmon resonance, showing that there are two non-equivalent binding sites for HsdR which differ in binding affinity by at least two orders of magnitude. DNA footprinting experiments using Exonuclease III suggest that the addition of HsdR to the methyltransferase (at a stoichiometry of either 1:1 or 2:1) increases the stability of the resulting DNA-protein complex but does not increase the size of the footprint. More extensive in situ footprinting experiments using copper-phenanthroline on the DNA-protein complexes formed by M2S, R1M2S and R2M2S also show no difference in the detailed cleavage pattern, with approximately 18 nucleotides protected on both strands in each complex. Thus the HsdR subunit(s) of the endonuclease stabilise the interaction of the M2S complex with DNA, but do not directly contribute to DNA binding. In addition, the thymidine nucleotide in the tetranucleotide recognition sequence GTCG is hyper-reactive to cleavage in each case, suggesting that the DNA structure in this region is altered in these complexes.     

The Dynamics of Indonesia's Urbanisation, 1980-2006

This study examines continuity and change in patterns of Indonesia's urbanisation during the boom economy until the decentralisation era, using data mainly from the National Population Census 1980-2000 and from the Village Potential (PODES) 2006. Urbanisation in Indonesia is still characterised by a heavy concentration of the urban population in a few large cities, notably the Jakarta Metropolitan Area (JMA), which might reflect an integration of Jakarta into the global economy. It might also reflect an interurban disparity, between large and smaller cities. The population on the fringes of large cities is growing rapidly, while in the inner cities it is increasing at a very low rate of growth. Urban spatial development in Java is shaping belts, which connect many of the large cities. The intermediate cities and small towns on the outer islands have a relatively higher population growth rate compared with those in Java, which might suggest that those towns and cities are playing a more significant role in regional development.     

Telephone administration of the SF-36 health survey: validation studies and population norms for adults in Queensland

The Rand Corporation medical outcomes short-form 36 health survey (SF-36) is a multidimensional measure of self-perceived general health status, which has been validated in adult populations in the United States and Great Britain, and, more recently, in an Australian population. The SF-36 is increasingly being used in health outcomes research internationally, mainly as a self-administered tool, and clearly has potential for use in Australia. This study aimed to assess the acceptability, reliability and validity of telephone administration of the instrument in the Queensland adult population, and to provide reliable population norms. We report the results of a telephone survey in which we interviewed 12,793 adults. It was the first large-scale, statewide application of the SF-36 in Australia. A response rate of 82 per cent was achieved, and the SF-36 satisfied psychometric criteria for reliability and construct validity. Population norms broken down by age and sex are provided. They will be important for the interpretation of future studies using the SF-36 in particular population or patient groups.     

Dynamic operability analysis of nonlinear process networks based on dissipativity

Most modern chemical plants are complex networks of multiple interconnected nonlinear process units, often with multiple recycle and by‐pass streams and energy integration. Interactions between process units often lead to plant‐wide operability problems (i.e., difficulties in process control). Plant‐wide operability analysis is often difficult due to the complexity and nonlinearity of the processes. This article provides a new framework of dynamic operability analysis for plant‐wide processes, based on the dissipativity of each process unit and the topology of the process network. Based on the concept of dissipative systems, this approach can deal with nonlinear processes directly. Developed from a network perspective, the proposed framework is also inherently scalable and thus can be applied to large process networks. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

Performance heuristics for GR(1) synthesis and related algorithms

Acta Informatica - Reactive synthesis for the GR(1) fragment of LTL has been implemented and studied in many works. In this work we present and evaluate a list of heuristics to potentially reduce...     

Thermohydraulic and entropy characteristics of Al2O3-water nanofluid in a ribbed interrupted microchannel heat exchanger

In this study, an interrupted microchannel heat sink with rib turbulators was studied for its thermohydraulic effectiveness and entropy generation in a compact space. The rib edges are modified to enhance the overall functioning of the system by reducing the pressure drop. The working fluid used was Al₂O₃-water nanofluid, and increasing the Reynolds number and nanoparticle concentration triggered a reduction in the heat sink's maximum temperature. These also offer a decrease in resistance to heat transfer, and there is an improvement in the evenness of the temperature of the interrupted microchannel heat sink, as regions with the likelihood of hot spot reduced drastically. At Re = 100, increasing the nanoparticle concentration from 0% to 4% enhanced the heat transfer coefficient by 38.41% for the interrupted microchannel heat sink-base (IMCH-B) configuration. Under similar conditions, the convective heat transfer coefficient for the interrupted microchannel heat sink-fillet (IMCH-F) increased by 43.69%. Furthermore, at 0.5% concentration, changing the Reynolds number from 100 to 700 augmented the heat transfer coefficient by 70.65%. Thus, the maximum temperature of the substrate's bottom surface was reduced by 53.83°C when the system was operated at Re = 700 and nanoparticle concentration of 4%. The IMCH-C also showed relatively close results at all observed volume fractions. For the IMCH-C, the maximum temperature of the bottom surface was reduced by 41.98°C at Re = 700 when compared with Re = 100% and 4% concentration. Although at high Reynolds numbers and concentrations, the pressure drops are higher, the performance enhancement criteria prove that the nanofluid is superior to water and the edge modifications show significant performance improvement. More importantly, the IMCH-F heat sink showed the optimum performance based on the performance evaluation criteria at Re = 300 and $\phi =2\%$ (ie, at this point, the heat transfer coefficient is maximum and the pressure drop is minimum). On the other hand, the optimal thermodynamic performance was observed at Re = 700 and $\phi =4\%$. The numerical results demonstrated a potential way to exploit nano-suspensions for thermal applications, especially for high-energy flux systems with compact space constraints.     

Harnessing the Excellent Mechanical,Barrier and Antimicrobial Properties of Zinc Oxide (ZnO) to Improve the Performance of Starch-based Bioplastic

ABSTRACT

The inherent properties of starch which are poor mechanical properties and its hydrophilicity that leads to poor long-term water absorption, fostered the incorporation of additives into starch-based bioplastic to enhance its mechanical and barrier properties. Zinc oxide (ZnO) nanoparticle as a lightweight material that is biocompatible, nontoxic, cost-effective and exhibit strong antibacterial activity can be considered as nano reinforcement of starch-based bioplastic. The present work studied the reinforcing effect of ZnO on the physical, mechanical and antibacterial properties of starch-based bioplastic. Bioplastic was prepared by melt-mixing starch and glycerol (3:1, w/w) with ZnO (1%, 2%, 3%, 4% and 5%, w/w). Bioplastic density and water contact angle increased with the increase of ZnO concentration. Bioplastic with the addition of 4% ZnO showed the lowest moisture content of 3.45%. Moreover, the decomposition temperature of bioplastic with ZnO increased slightly which indicated the higher stability. Mechanical properties evaluation showed that bioplastic with addition of ZnO had higher tensile strength than that without ZnO where 4% ZnO exhibited the highest tensile strength of 10.29 MPa with elongation of 5.69%. Cross-section microstructure after tensile test showed that ZnO was fairly dispersed in starch matrix that implied the increase of the mechanical properties of bioplastic. FTIR spectra exhibited that the intermolecular interaction in bioplastics occurred through C–H, C=O, C–O–H and O–H groups. In addition, biodegradability tests of bioplastic showed that the growth of microbes decreased in the presence of ZnO due to the nature of ZnO as an antibacterial compound. The results showed that ZnO played a key role in reinforcing the physical, mechanical and antibacterial properties of starch-based bioplastic.