Search for Bs0B^{0}_{s} oscillations using inclusive lepton events

A search for Bs oscillations is performed using a sample of semileptonic b-hadron decays collected by the ALEPH experiment during 1991-1995. Compared to previous inclusive lepton analyses, the prop er time resolution and b-flavour mistag rate are significantly improved. Additional sensitivity to Bs mixing is obtained by identifying subsamples of events having a Bs purity which is higher than the average for the whole data sample. Unbinned maximum likelihood amplitude fits are performed to derive a lower limit of Dms>9.5 ps-1 at 95% CL. Combining with the ALEPH Ds based analyses yields Dms>9.6 ps-1 at 95% CL.A search for B0s oscillations is performed using a sample of semileptonic b-hadron decays collected by the ALEPH experiment during 1991-1995. Compared to previous inclusive lepton analyses, the proper time resolution and b-flavour mistag rate are significantly improved. Additional sensitivity to B0s mixing is obtained by identifying subsamples of events having a B0s purity which is higher than the average for the whole data sample. Unbinned maximum likelihood amplitude fits are performed to derive a lower limit of Deltam_s>9.5ps^-1 at 95% CL. Combining with the ALEPH D-s based analyses yields Deltam_s>9.6ps^-1 at 95% CL

Classification of current anticancer immunotherapies

During the past decades, anticancer immunotherapy has evolved from a promising therapeutic option to a robust clinical reality. Many immunotherapeutic regimens are now approved by the US Food and Drug Administration and the European Medicines Agency for use in cancer patients, and many others are being investigated as standalone therapeutic interventions or combined with conventional treatments in clinical studies. Immunotherapies may be subdivided into “passive” and “active” based on their ability to engage the host immune system against cancer. Since the anticancer activity of most passive immunotherapeutics (including tumor-targeting monoclonal antibodies) also relies on the host immune system, this classification does not properly reflect the complexity of the drug-host-tumor interaction. Alternatively, anticancer immunotherapeutics can be classified according to their antigen specificity. While some immunotherapies specifically target one (or a few) defined tumor-associated antigen(s), others operate in a relatively non-specific manner and boost natural or therapy-elicited anticancer immune responses of unknown and often broad specificity. Here, we propose a critical, integrated classification of anticancer immunotherapies and discuss the clinical relevance of these approaches

Analysis of the performance of a multi-bed adsorption heat pump using a solid-side resistance model

An analysis of the coefficient of performance and specific cooling power for a four-bed adsorption heat pump, using a solid-side resistance model, is presented. Methanol and an activated carbon are the adsorption pair. An Arrhenius form of solid-side mass diffusivity was adopted. A plate-fin type insert was considered as the heating/cooling element in adsorbers. The result shows that, for large grainsize activated carbon, the intra-particle mass diffusion resistance significantly affects the adsorption and regeneration rates. Both the coefficient of performance and the specific cooling power increase with the overall heat transfer coefficient, regeneration and evaporation temperatures, but decrease with an increase of the condensing temperature and time constant of the insert. The coefficient of performance considerably increases with a decrease of the insert heat capacitance. An optimum cycle time, corresponding to a maximum specific cooling power, was found. To achieve a high specific cooling power for short cycle time operations, small grain-size activated carbon should be selected as the adsorbent. In addition, a small time constant of the insert and a large overall heat transfer coefficient are also highly recommended. (c) 2006 Elsevier Ltd. All rights reserved

Effects of jet plate size and plate spacing on the stagnation Nusselt number for a confined circular air jet impinging on a flat surface

This work deals with the effects of jet plate size and plate spacing (jet height) on the heat transfer characteristics for a confined circular air jet vertically impinging on a flat plate. The jet after impingement was restricted to flow in two opposite directions. A constant surface heat flux of 1000 W/m(2) was arranged. Totally 88 experiments were performed. Jet orifices individually with diameter of 1.5, 3, 6 and 9 mm were adopted. Jet Reynolds number (Re) was in the range 10,000-30,000 and plate spacing-to-jet diameter ratio (H/d) was in the range 1-6. Eleven jet plate width-to-jet diameter ratios (W/d = 4.17-41.7) and seven jet plate length-to-jet diameter ratios (L/d = 5.5-166.7) were individually considered. The measured data were correlated into a simple equation. It was found that the stagnation Nusselt number is proportional to the 0.638 power of the Re and inversely proportional to the 0.3 power of the H/d. The stagnation Nusselt number was also found to be a function of exp[-0.044(W/d) - 0.01 I(L/d)]. Through comparisons among the present obtained data and documented results, it may infer that, for a jet impingement, the impingement-plate heating condition and flow arrangement of the jet after impingement are two important factors affecting the dependence of the stagnation Nusselt number on H/d. (c) 2006 Elsevier Ltd. All rights reserved

Second-law analysis of a wet crossflow heat exchanger

A second-law analysis of a wet crossflow heat exchanger is performed for various weather conditions. The heat exchanger can be used as an energy-saving device for ventilation in air-conditioning. The heat and mass transfer is solved by using the model developed by Holmberg. The effectiveness, exergy recovery factor and second-law efficiency of the wet heat exchanger are individually defined. The effects of lateral solid heat conduction on the effectiveness, exergy recovery factor and second-law efficiency are numerically investigated for various operating conditions. Two optimum design criteria, one for the maximum second law efficiency and the other for the maximum exergy recovery factor, are obtained. (C) 2000 Elsevier Science Ltd. All rights reserved

Comparison among three adsorption pairs for using as the working substances in a multi-bed adsorption heat pump

A comparison among three adsorption pairs (activated carbon-methanol, silica gel-water and 13X molecular sieves-water) for using as the working substances in a four-bed adsorption heat pump is presented. A solid-side resistance model considering a finite mass flow-rate of heating/cooling fluid was adopted. The result shows that, for small mass flowrates of the heating/cooling fluid, assuming a constant temperature for the heating/cooling fluid might give rise to an over-predication of the system performance. For the adsorption heat pump, there exists an optimum mode operating time (T) which corresponds to a maximum specific cooling power. For operations at the maximum specific cooling power (tau = 3-6 min) and with regeneration temperatures in the range 80-120 degrees C, among the three adsorption pairs, the activated carbon-methanol pair leads to the highest specific cooling power, COP value and second-law efficiency. For the silica gel-water pair, the temperature rise resulting from adsorption heat significantly downgrades the system performance. This causes its corresponding specific cooling power, COP value and second-law efficiency to be lower than those for the activated carbon-methanol pair. The 13X molecular sieves-water pair possesses the smallest cyclic variation of adsorbate content, thus it yields the lowest specific cooling power, COP value and second-law efficiency. (c) 2007 Elsevier Ltd. All rights reserved

Heat transfer enhancement of transverse ribs in circular tubes with consideration of entrance effect

The heat transfer enhancement of transverse ribs in circular tubes with a length-to-diameter ratio of 87 was experimentally investigated. The mean heat transfer and friction data were obtained for the air flow started from the entrance. An isothermal surface condition was considered. The rib pitch-to-tube diameter ratio (p/d) was in the range 0.304-5.72; the rib height-to-tube diameter ratio (e/d) was in the range 0.015-0.143; the considered Reynolds number (Re) was in the range 4608-12,936. The mean Nusselt number (Nu) and friction factor (f) were individually correlated as a function of p/d, e/d and Re. A critical e/d, equal to 0.057, was found. For e/d = 0.057, the f is proportional to (e/d)(2.55). A performance map, indicating the corresponding heat transfer enhancement index (r(1)) and efficiency index (r(2)) for various p/d and e/d, was constructed. This performance map clearly indicates the ranges of p/d and e/d with a high r(2). (c) 2006 Elsevier Ltd. All rights reserved

Mass diffusion in a spherical microporous particle with thermal effect and gas-side mass transfer resistance

An analytical solution for mass diffusion in a spherical microporous particle experienced with a small step change of gaseous phase adsorbate concentration is obtained. The mass diffusion in the solid is assumed to be micropore diffusion controlled. Thermal effect and gas-side mass transfer resistance are considered. The governing equations are solved by using the Laplace transformation method. Three factors, alpha, beta and gamma are defined to govern the heat and mass transfer. alpha and beta are relevant to the thermal effect and gamma dominates the gas-side mass transfer resistance. The applicable ranges of three simplified models are discussed. A limiting solution with mass diffusivity approaching infinity is obtained. (C) 2000 Elsevier Science Ltd. All rights reserved

Second-law performance of heat exchangers for waste heat recovery

Exergy change rate in an ideal gas flow or an incompressible flow can be divided into a thermal exergy change rate and a mechanical exergy loss rate. The mechanical exergy loss rates in the two flows were generalized using a pressure-drop factor. For heat exchangers using in waste heat recovery, the consumed mechanical exergy is usually more valuable than the recovered thermal exergy. A weighing factor was proposed to modify the pressure-drop factor. An exergy recovery index (eta(parallel to)) was defined and it was expressed as a function of effectiveness (epsilon), ratio of modified heat capacity rates (C), hot stream-to-dead-state temperature ratio, cold stream-to-dead-state temperature ratio and modified overall pressure-drop factor. This eta(parallel to)-epsilon relation can be used to find the eta(parallel to) value of a heat exchanger with any flow arrangement. The eta(parallel to)-Ntu and eta(parallel to)-Ntu(h) relations of cross-flow heat exchanger with both fluids unmixed were established respectively. The former provides a minimum Ntu design principle and the latter provides a minimum Ntu(h) design principle. A numerical example showed that, at a fixed heat capacity rate of the hot stream, the heat exchanger size yielded by the minimum Ntu(h) principle is smaller than that yielded by the minimum Ntu principle. (C) 2010 Elsevier Ltd. All rights reserved

Adsorption of toluene on activated carbon in a packed bed

A simulation of the performance of an activated carbon packed-bed system for adsorption of toluene from air is performed. For a non-switched operation the time-varying exit toluene concentration of a 30 mm-depth bed is measured. The simulation result is compared with the measured data. The computer analysis is based on a modified solid-side resistance model which was originally proposed by Pesaran and Mills. The effects of cycle operating time, regeneration temperature and Ntu on the adsorption performance are investigated. The maximum removal and the corresponding optimum cycle time are obtained. The influence of the number of grid points on the accuracy of the numerical scheme is discussed. The effects of tortuosity factor and transfer coefficients on the adsorption are investigated. (C) 1998 Elsevier Science Ltd. All rights reserved