An in-situ temperature measurement system for DUV lithography

Spatial uniformity of temperature across a silicon wafer is an important requirement during the post-exposure bake step of the deep-ultra-violet lithography process. Closed-loop temperature control provides a means by which the stringent temperature specifications can be achieved, provided that accurate feedback signal is available. As each new wafer is loaded for processing, its level of thermal contact with the temperature sensor may vary, leading to erroneous measurement of the wafer temperature. Such variation in thermal contact manifests itself as changes in the time constant of the sensor. This paper describes a method for in-situ estimation of the sensor parameters, and proposes an algorithm for post-processing the sensor output to improve measurement accuracy. Experimental results are presented to demonstrate the effectiveness of the algorithm in improving the accuracy of the feedback signal, thereby reducing the undesirable influence of poor thermal contact on the performance of the closed-loop temperature control system.     

NUMERICAL SIMULATIONS OF ELECTRO-SLAG REMELTING PROCESS

Flow and heat transfer characteristics in the electro-slag remelting process (ESR) are important in manufacturing steel of good quality. An integrated numerical model is developed to compute the flow field and the temperature distribution inside ESR units with a metal pool profile which is solved simultaneously. In addition to the conservative equations of mass, momentum, energy, and turbulent properties, Maxwell's equations are employed to obtain the electromagnetic field by either AC or DC power supply. The results include the effects of power supply type, current amplitude, casting rate, and flow field patterns (laminar or turbulent) on flow and heat transfer characteristics. Different flow patterns and turbulent properties have been predicted using a pool profile close to the real one for AC and DC power supplies. The present model concludes that the casting rate and current amplitude are very effective in affecting the pool shape.     

Optimal control of a queueing system with two heterogeneous servers

The problem considered is that of optimally controlling a queueing system which consists of a common buffer or queue served by two servers. The arrivals to the buffer are Poisson and the servers are both exponential, but with different mean service times. It is shown that the optimal policy which minimizes the mean sojourn time of customers in the system is of threshold type. The faster server should be fed a customer from the buffer whenever it becomes available for service, but the slower server should be utilized if and only if the queue length exceeds a readily computed threshold value.     

Plasticized poly(lactic acid) with low molecular weight poly(ethylene glycol): Mechanical,thermal, and morphology properties

Poly(lactic acid) PLA was plasticized with low molecular weight poly(ethylene glycol) PEG‐200 to improve the ductility of PLA, while maintaining the plasticizer content at maximum 10 wt%. Low molecular weight of PEG enables increased miscibility with PLA and more efficient reduction of glass transition temperature (T_g). This effect is enhanced not only by the low molecular weight but also by its higher content. The tensile properties demonstrated that the addition of PEG‐200 to PLA led to an increase of elongation at break (>7000%), but a decrease of both tensile strength and tensile modulus. The plasticization of the PLA with PEG‐200 effectively lowers T_g as well as cold‐crystallization temperature, increasing with plasticizer content. SEM micrographs reveal plastic deformation and few long threads of a deformed material are discernible on the fracture surface. The use of low molecular weight PEG‐200 reduces the intermolecular force and increases the mobility of the polymeric chains, thereby improving the flexibility and plastic deformation of PLA. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4576–4580, 2013     

Numerical studies on micropart self-alignment using surface tension forces

The Fluidic Self-Alignment Approach provides an alternative means for fast, economic, and precise handling of thousands of micro-scale parts. The present study aims to examine the important parameters which govern the mechanisms of the fluidic self-assembly process by numerical simulations. A simplified 2D model system consists of a solid plate, a micro-scale liquid slug and a micropart. The computational model is based on first principle conservation equations and is constructed by the coupling of two-phase modeling, solid structure modeling, and fluid–structure coupling. A matching experimental system is set up for the micropart of aspect ratio from 3:1 to 10:1 to validate the 2D computational simulations. Simulations reveal that a high degree of hydrophilicity between the lubricant and the solid surfaces is required for the self-assembly of microparts. A lower lubricant height, a higher surface tension coefficient and a higher viscosity enforce the re-alignment/restoration process also. Characterization of the flow field inside lubricant slug also indicates that the asymmetry of the vortices/stress distribution at both ends of the lubricant meniscus is resulted as the micropart in a back-and-forth restoration process.     

Phase Separation-Mediated Chromatin Organization and Dynamics: From Imaging-Based Quantitative Characterizations to Functional Implications

As an effective and versatile strategy to compartmentalize cellular components without the need for lipid membranes, phase separation has been found to underpin a wide range of intranuclear processes, particularly those involving chromatin. Many of the unique physico-chemical properties of chromatin-based phase condensates are harnessed by the cell to accomplish complex regulatory functions in a spatially and temporally controlled manner. Here, we survey key recent findings on the mechanistic roles of phase separation in regulating the organization and dynamics of chromatin-based molecular processes across length scales, packing states and intranuclear functions, with a particular emphasis on quantitative characterizations of these condensates enabled by advanced imaging-based approaches. By illuminating the complex interplay between chromatin and various chromatin-interacting molecular species mediated by phase separation, this review sheds light on an emerging multi-scale, multi-modal and multi-faceted landscape that hierarchically regulates the genome within the highly crowded and dynamic nuclear space. Moreover, deficiencies in existing studies also highlight the need for mechanism-specific criteria and multi-parametric approaches for the characterization of chromatin-based phase separation using complementary techniques and call for greater efforts to correlate the quantitative features of these condensates with their functional consequences in close-to-native cellular contexts.     

Nociceptin receptor coupling to a potassium conductance in rat locus coeruleus neurones in vitro

1. In this study we have examined the effects of nociceptin, an endogenous ligand for the opioid-like receptor ORL1 on the membrane properties of rat locus coeruleus (LC) neurones in vitro, using intracellular and whole cell patch clamp recording. 2. When locus coeruleus neurones were voltage clamped to -60 mV, application to nociceptin caused an outward current in all cells examined (n = 49), with an EC50 of 90 nM. Neither the potency nor the maximal effect of nociceptin was altered in the presence of the peptidase inhibitors, bestatin (20 microM) or thiorphan (2 microM). 3. The outward currents caused by nociceptin in 2.5 mM extracellular K+ reversed polarity at -123 mV, more negative than the predicted K+ reversal potential of -105 mV. Increasing extracellular K+ to 6.5 mM resulted in a shift of the reversal potential of +25 mV, a shift consistent with a K+ conductance. The conductance activated by nociceptin showed mild inward rectification. 4. Application of a high concentration of nociceptin (3 microM) occluded the current produced by simultaneous application of high concentrations of Met-enkephalin (10 microM), (3 microM) somatostatin and UK 14304 (3 microM), indicating that nociceptin activated the same conductance as mu-opioid and somatostatin receptors and alpha 2-adrenoceptors. 5. The actions of nociceptin were weakly antagonized by the opioid antagonist, naloxone, with pKb's estimated from 2 cells of -4.23 and -4.33. The mu-opioid antagonist, CTAP (D-Phe-Cys-Tyr-D-Trp-Arg-Pen-Thr-NH2, 1 microM), the opioid antagonist, nalorphine (30 microM) or the somatostatin antagonist, CPP (cyclo(7-aminoheptanoyl-Phe-D-Trp-Lys-Thr[Bz1]) 3 microM) did not affect the nociceptin-induced current. 6. Dynorphin A (microM), another putative endogenous ligand for ORL1, caused a robust outward current in locus coeruleus neurones that was, however, completely antagonized by moderate concentrations of naloxone (300 nM-1 microM). 7. Continuous application of nociceptin (3 microM) resulted in a decrease of the outward current to a steady level of 70% of the maximum response with a t1/2 of 120s. Desensitization was largely homologous because simultaneous application of Met-enkephalin (30 microM) during the desensitized period of the nociceptin response resulted in an outward current that was 92% of control responses to Met-enkephalin in the same cells. Conversely, continuous application of Met-enkephalin (30 microM) resulted in a decrease of Met-enkephalin current to a steady level that was 54% of the initial current. During this desensitized period application of nociceptin (3 microM) resulted in a current that was 78% of the control responses to nociceptin in the same cells. 8. Thus nociceptin potently activates an inwardly rectifying K+ conductance in locus coeruleus neurones, with a pharmacological profile consistent with activation of the ORL1 receptor. Dynorphin A does not appear to be a ligand for ORL1 in rat locus coeruleus neurones.     

Myricetin attenuates lipopolysaccharide‐stimulated activation of mouse bone marrow‐derived dendritic cells through suppression of IKK/NF‐κB and MAPK signalling pathways

BACKGROUND: Myricetin is a naturally occurring flavonoid that is found in many fruits, vegetables, teas and medicinal herbs. It has been demonstrated to have anti‐inflammatory properties, but, to date, no studies have described the immunomodulatory effects of myricetin on the functions of dendritic cells (DCs). The aim of this study was to evaluate the potential for myricetin to modulate lipopolysaccharide (LPS)‐stimulated activation of mouse bone marrow‐derived DCs. RESULTS: Our experimental data showed that treatment with myricetin up to 10 µg mL⁻¹ does not cause cytotoxicity in cells. Myricetin significantly decreased the secretion of tumour necrosis factor‐α, interleukin‐6 and interleukin‐12p70 by LPS‐stimulated DCs. The expression of LPS‐induced major histocompatibility class II, CD40 and CD86 on DCs was also inhibited by myricetin, and the endocytic and migratory capacity of LPS‐stimulated DCs was blocked by myricentin. In addition, LPS‐stimulated DC‐elicited allogeneic T‐cell proliferation was reduced by myricetin. Moreover, our results confirmed that myricetin attenuates the responses of LPS‐stimulated activation of DCs via suppression of IκB kinase/nuclear factor‐κB and mitogen‐activated protein kinase‐dependent pathways. CONCLUSION: Myricetin has novel immunopharmacological activity, and modulation of DCs by myricetin may be an attractive strategy for the treatment of inflammatory and autoimmune disorders, and for transplantation. Copyright © 2012 Society of Chemical Industry     

Endwall heat transfer and pressure drop in scale-roughened pin-fin channels

There is a growing requirement for improved heat transfer performance for a number of electronic devices and this dictates a need to further elevate the endwall heat transfer performances for pin-fin channels. Driven by this need, a novel compound heat transfer enhancement (HTE) measure that combines deepened scales and pin-fin array is devised. Characteristics of heat transfer and pressure drop performances in two scale-roughened pin-fin channels with two different pin pitch-to-diameter ratios are compared for both forward and backward flows in the Reynolds Number (Re) range of 1000–30000. Comparisons of heat transfer data, pressure drop measurements and thermal performance factors with previous results collected from a variety of single and compound HTE devices demonstrate the significant augmentations in both heat transfer rates and pressure drop coefficients for the present HTE measure. This present compound HTE measure with scales and pin-fin array demonstrates an enhancement on the heat transfer up to of 22 times of the developed flow references in smooth-walled pipe within the Re range of 1000–30000. Experimental correlations of heat transfer and pressure-drop coefficients for two scale-roughened pin-fin channels with forward and backward flows are derived to assist design applications.