Home About us Contact
|
Home About us Contact | ||
|
|
||
Economic Way (economic + way)
Selected AbstractsCross-strain protection reduces effectiveness of virally vectored fertility control: results from individual-based multistrain modelsJOURNAL OF APPLIED ECOLOGY, Issue 6 2007ANTHONY D. ARTHUR Summary 1Pest mammals have severe economic, environmental and social impacts throughout the world. Fertility control could reduce these impacts. Virally vectored immunocontraception (VVIC) has been proposed as an economic way to achieve this. However, the ability of an immunocontraceptive virus to control populations may be compromised if: (i) sufficient infected mice are not made infertile; (ii) the virus does not transmit at a sufficient rate; (iii) there is competition with field strains of virus; or (iv) its ability to induce infertility is altered by the presence of field strains. We tested this with stochastic, individual-based, disease,host models based on murine cytomegalovirus (MCMV) and house mice Mus musculus domesticus. 2Using field estimates of the MCMV transmission rate, immunocontraceptive MCMV (icMCMV) could prevent mouse populations from growing rapidly to damaging levels provided > 70% of mice infected with the virus became infertile. Successful control was possible even if engineering icMCMV reduced its transmission rate to c. 30% of the field-estimated value, but greater reductions in the transmission rate compromised successful control. 3Effective control was compromised if there was competition between icMCMV and field strains because of cross-immunity to infection or if previous infection with field strains blocked the development of infertility in mice subsequently infected with icMCMV. In these cases effectiveness was diminished, particularly if the transmission rate of icMCMV was reduced relative to field strains, or if close to 100% infertility of infected mice could not be achieved. If the blocking developed early after infection with field strains, doubling the transmission rate of icMCMV relative to field strains still could not produce successful control. 4Synthesis and applications. VVIC requires preliminary estimates of its efficacy to satisfy regulatory requirements before it can be released into the environment. Our models indicate that successful control of an outbreaking species using VVIC is possible if high levels of infertility can be achieved, but this is compromised by cross-strain protection and low transmission rates of engineered virus. Future research effort should focus on determining whether these compromising effects occur for specific engineered viruses and, if so, whether they can be overcome. [source] PRESERVATION OF "UMBU" (SPONDIAS TUBEROSA ARRUDA CÂMARA) PULP IN THE GREEN STAGE OF MATURATION BY COMBINED METHODSJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 3 2007ELIDA CONCEIÇÃO JORGE ABSTRACT "Umbu" (Spondias tuberosa Arruda Câmara) is a typical fruit from northeastern Brazil of considerable economic importance to this region, because several products are derived from it and commercialized, especially the pulp, which can be used as a raw material for preserves and juices. The objective of this research was to study the preservation of umbu in the green stage of maturation by combined methods, including heat treatment and the addition of preservatives and sucrose. The pulps were blanched, pasteurized and mixed with the preservatives and sucrose according to a complete factorial design with three variables (ratio pulp/sucrose, potassium sorbate and sodium metabisulfite), two levels and two repetitions. The products were filled into high-density polyethylene packages and exposed to a temperature of 40C for 120 days. Physicochemical, color and chemical (SO2) analyses showed that the concentrations of sodium metabisulfite and potassium sorbate used did not significantly alter product quality. The addition of sucrose significantly decreased the water activity and led to intense browning. The microbiological evaluations showed good product stability for 120 days. The overall results indicated that the heat treatment applied was effective if high levels of hygiene were maintained during the preparatory stages and the packaging materials were well sanitized. The combined preservation methods appear to be an economic way to preserve these high-acid pulps. [source] Modeling the partial nitrification in sequencing batch reactor for biomass adapted to high ammonia concentrationsBIOTECHNOLOGY & BIOENGINEERING, Issue 1 2006V. Pambrun Abstract Partial nitrification has proven to be an economic way for treatment of industrial N-rich effluent, reducing oxygen and external COD requirements during nitrification/denitrification process. One of the key issues of this system is the intermediate nitrite accumulation stability. This work presents a control strategy and a modeling tool for maintaining nitrite build-up. Partial nitrification process has been carried out in a sequencing batch reactor at 30°C, maintaining strong changing ammonia concentration in the reactor (sequencing feed). Stable nitrite accumulation has been obtained with the help of an on-line oxygen uptake rate (OUR)-based control system, with removal rate of 2 kg NH -N,·,m,3/day and 90%,95% of conversion of ammonium into nitrite. A mathematical model, identified through the occurring biological reactions, is proposed to optimize the process (preventing nitrate production). Most of the kinetic parameters have been estimated from specific respirometric tests on biomass and validated on pilot-scale experiments of one-cycle duration. Comparison of dynamic data at different pH confirms that NH3 and NO should be considered as the true substrate of nitritation and nitratation, respectively. The proposed model represents major features: the inhibition of ammonia-oxidizing bacteria by its substrate (NH3) and product (HNO2), the inhibition of nitrite-oxidizing bacteria by free ammonia (NH3), the INFluence of pH. It appears that the model correctly describes the short-term dynamics of nitrogenous compounds in SBR, when both ammonia oxidizers and nitrite oxidizers are present and active in the reactor. The model proposed represents a useful tool for process design and optimization. © 2006 Wiley Periodicals, Inc. [source] A rapid, sensitive and economical assessment of monoclonal antibody conformational stability by intrinsic tryptophan fluorescence spectroscopyBIOTECHNOLOGY JOURNAL, Issue 9-10 2008Patrick Garidel Dr. Abstract Steady-state intrinsic tryptophan fluorescence spectroscopy is used as a rapid, robust and economic way for screening the thermal protein conformational stability in various formulations used during the early biotechnology development phase. The most important parameters affecting protein stability in a liquid formulation, e. g. during the initial purification steps or preformulation development, are the pH of the solution, ionic strength, presence of excipients and combinations thereof. A well-defined protocol is presented for the investigation of the thermal conformational stability of proteins. This allows the determination of the denaturation temperature as a function of solution conditions. Using intrinsic tryptophan fluorescence spectroscopy for monitoring the denaturation and folding of proteins, it is crucial to understand the influence of different formulation parameters on the intrinsic fluorescence probes of proteins. Therefore, we have re-evaluated and re-assessed the influence of temperature, pH, ionic strength, buffer composition on the emission spectra of tryptophan, phenylalanine and tyrosine to correctly analyse and evaluate the data obtained from thermal-induced protein denaturation as a function of the solution parameters mentioned above. The results of this study are a prerequisite for using this method as a screening assay for analysing the conformational stability of proteins in solution. The data obtained from intrinsic protein fluorescence spectroscopy are compared to data derived from calorimetry. The advantage, challenges and applicability using intrinsic tryptophan fluorescence spectroscopy as a routine development method in pharmaceutical biotechnology are discussed. [source] Structural Evolvement of Heating Treatment of Mg/Al-LDH and Preparation of Mineral Mesoporous MaterialsACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 2 2006CHEN Tianhu Abstract, Although hydrotalcite, or layered double hydroxides (LDHs), is not a common mineral, it is an important material that can be easily synthesized in laboratory. In this study, structural evolvement and BET surface area changes of heat treated Mg/Al-LDH is evaluated by XRD, TEM and N2 -BET analyses. The results indicate that the magnesium-aluminum LDH with carbonate as interlayer anion, periclase-like oxides was formed at temperatures of 400,800°C. Meanwhile, 2,3 nanometer mesoporous were formed during decomposition of LDH. However, the heat treated samples still preserve the morphology of the original LDH plates. Periclase-like formed from LDH heat treatment may re-hydrolyze and recover the structure of LDH. However, crystallinity of the recovered LDH is lower than that of the original LDH. This heat treatment will result in formation of (Mg, Al)-oxide nano-crystals and nanopores among the nano-crystals. When heating temperature exceeds 1000, the periclase-like (Mg, Al)-oxide is transformed into a composite with periclase (MgO) and spinel phases. The periclase can be re-hydrolyzed and dissolved in HCI solution. After acid treatment, the sample with a high surface area is composed of spinel nano-crystals and nanopores among them. Our results will provide a new and economic way to synthesize mesoporous materials through pathways of phase transformation of precursor materials with different composition. [source] Colloidal Noble-Metal and Bimetallic Alloy Nanocrystals: A General Synthetic Method and Their Catalytic Hydrogenation PropertiesCHEMISTRY - A EUROPEAN JOURNAL, Issue 21 2010Shuyan Song Dr. Abstract A general single-step strategy has been developed for the direct thermal decomposition of noble-metal salts in octadecylamine to synthesize octahedron- and rod-shaped noble-metal aggregates and monodisperse noble-metal or bimetallic alloy nanocrystals without introducing any additive into the system. It has presented a facile and economic way to fabricate these nanocrystals, especially alloy nanocrystals, which does not require a post-synthesis solid-state annealing process. The morphology of the nanocrystals can be easily controlled by tuning the synthetic temperature. Their ability to catalyze heterogeneous Suzuki coupling reactions has been investigated and showed satisfactory catalytic activity. The catalytic performance of the monometallic and bimetallic alloy nanocrystals were also evaluated in the selective hydrogenation of citral in a conventional organic solvent (toluene) and a green solvent (supercritical carbon dioxide, scCO2). Interestingly, the catalysts performed differently to each other when they were in scCO2 owing to the different morphology, which should be readily optimized for further use. [source] Highly Efficient Access to Bi- and Tricyclic Ketals through Gold-Catalyzed Tandem Reactions of 4-Acyl-1,6-diynesCHEMISTRY - A EUROPEAN JOURNAL, Issue 8 2009Jia Meng Dr. Abstract Single step: Fused bicyclic and bridged tricyclic ketals were synthesized in a single step from the reactions of easily available 4-acyl-1,6-diynes with H2O and alkanols (see scheme). The highly efficient AuCl3 -catalyzed multicomponent domino reactions, involving five CO bond formations, can proceed in a highly regio- and diastereoselective manner at room temperature under air and lead to structures of high molecular complexity from simple starting materials in an atom economic way. [source] | |||||||||||||