The chemical structure of the very young starless core L1521E

L1521E is a dense starless core in Taurus that was found to have relatively low molecular depletion by earlier studies, thus suggesting a recent formation. We aim to characterize the chemical structure of L1521E and compare it to the more evolved L1544 pre-stellar core. We have obtained $\sim$2.5$\times$2.5 arcminute maps toward L1521E using the IRAM-30m telescope in transitions of various species. We derived abundances for the species and compared them to those obtained toward L1544. We estimated CO depletion factors. Similarly to L1544, $c$-C$_3$H$_2$ and CH$_3$OH peak at different positions. Most species peak toward the $c$-C$_3$H$_2$ peak. The CO depletion factor derived toward the $Herschel$ dust peak is 4.3$\pm$1.6, which is about a factor of three lower than that toward L1544. The abundances of sulfur-bearing molecules are higher toward L1521E than toward L1544 by factors of $\sim$2-20. The abundance of methanol is similar toward the two cores. The higher abundances of sulfur-bearing species toward L1521E than toward L1544 suggest that significant sulfur depletion takes place during the dynamical evolution of dense cores, from the starless to pre-stellar stage. The CO depletion factor measured toward L1521E suggests that CO is more depleted than previously found. Similar CH$_3$OH abundances between L1521E and L1544 hint that methanol is forming at specific physical conditions in Taurus, characterized by densities of a few $\times$10$^4$ cm$^{-3}$ and $N$(H$_2$)$\gtrsim$10$^{22}$ cm$^{-2}$, when CO starts to catastrophically freeze-out, while water can still be significantly photodissociated, so that the surfaces of dust grains become rich in solid CO and CH$_3$OH, as already found toward L1544. Methanol can thus provide selective crucial information about the transition region between dense cores and the surrounding parent cloud.Comment: Accepted for publication in A&A, abstract abridge

Vibrational Stability of NLC Linac accelerating structure

The vibration of components of the NLC linac, such as accelerating structures and girders, is being studied both experimentally and analytically. Various effects are being considered including structural resonances and vibration caused by cooling water in the accelerating structure. This paper reports the status of ongoing work.Comment: 3 pages 8 figures Presented at EPAC 2002 Paris Franc

Lab-on-Chip for Testing Myelotoxic Effect of Drugs and Chemicals

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.In the last twenty years, one of the main goals in the drug discovery field has been the development of reliable in vitro models. In particular, in 2006 the European Centre for the Validation of Alternative Methods (ECVAM) has approved the Colony forming Unit-Granulocytes-Macrophages (CFU-GM) test, which is the first and currently unique test applied to evaluate the myelotoxicity of xenobiotics in vitro. The present work aimed at miniaturizing this in vitro assay by developing and validating a Lab-on-Chip (LoC) platform consisting of a high number of bioreactor chambers with screening capabilities in a high-throughput regime

Microfluidic Platform for Adherent Single Cell High-Throughput Screening

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.Traditionally, in vitro investigations on biology and physiology of cells rely on averaging the responses eliciting from heterogeneous cell populations, thus being unsuitable for assessing individual cell behaviors in response to external stimulations. In the last years, great interest has thus been focused on single cell analysis and screening, which represents a promising tool aiming at pursuing the direct and deterministic control over cause-effect relationships guiding cell behavior. In this regard, a high-throughput microfluidic platform for trapping and culturing adherent single cells was presented. A single cell trapping mechanism was implemented based on dynamic variation of fluidic resistances. A round-shaped culture chamber (Φ=250μm, h=25μm) was conceived presenting two connections with a main fluidic path: (i) an upper wide opening, and (ii) a bottom trapping junction which modulates the hydraulic resistance. Several layouts of the chamber were designed and computationally validated for the optimization of the single cell trapping efficacy. The optimized chamber layouts were integrated in a polydimethylsiloxane (PDMS) microfluidic platform presenting two main functionalities: (i) 288 chambers for trapping single cells, and (ii) a chaoticmixer based serial dilution generator for delivering both soluble factors and non-diffusive molecules under spatio-temporally controlled chemical patterns. The devices were experimentally validated and allowed for trapping individual U87-MG (human glioblastoma-astrocytoma epithelial-like) cells and culturing them up to 3 days

Final Implementation and Performance of the LHC Collimator Control System

The 2008 collimation system of the CERN Large Hadron Collider (LHC) included 80 movable collimators for a total of 316 degrees of freedom. Before beam operation, the final controls implementation was deployed and commissioned. The control system enabled remote control and appropriate diagnostics of the relevant parameters. The collimator motion is driven with time-functions, synchronized with other accelerator systems, which allows controlling the collimator jaw positions with a micrometer accuracy during all machine phases. The machine protection functionality of the system, which also relies on function-based tolerance windows, was also fully validated. The collimator control challenges are reviewed and the final system architecture is presented. The results of the remote system commissioning and the overall performance are discussed

Manejo de Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) na cultura do morangueiro no Rio Grande do Sul.

Esta Circular Técnica tem como objetivo descrever a biologia de F. occidentalis na cultura do morangueiro, caracterizar o tipo de injúria causada pelo inseto em flores e frutos e fornecer informações para o monitoramento e o controle da espécie na cultura no Estado do Rio Grande do Sul.bitstream/item/73816/1/cir090.pd

Micromixing and microchannel design: Vortex shape and entropy

This paper was presented at the 2nd Micro and Nano Flows Conference (MNF2009), which was held at Brunel University, West London, UK. The conference was organised by Brunel University and supported by the Institution of Mechanical Engineers, IPEM, the Italian Union of Thermofluid dynamics, the Process Intensification Network, HEXAG - the Heat Exchange Action Group and the Institute of Mathematics and its Applications.In very recent years microdevices, due to their potency in replacing large-scale conventional laboratory instrumentation, are becoming a fast and low cost technology for the treatment of several chemical and biological processes. In particular microfluidics has been massively investigated, aiming at improving the performance of chemical reactors. This is because of the fact that reaction is often an interface phenomenon where the greater the surface to volume ratio, the higher the reaction speed, and microscale mixing increases the interfacial area (in terms of mixing-induced-by-vortices generation). However, microfluidic systems suffer from the limitation that they are characterized mostly by very low Reynolds numbers, with the consequence that (i) they cannot take advantage from the turbulence mixing support, and (ii) viscosity hampers proper vortex detection. Therefore, the proper design of micro-channels (MCs) becomes essential. In this framework, several geometries have been proposed to induce mixing vortices in MCs. However a quantitative comparison between proposed geometries in terms of their passive mixing potency can be done only after proper definition of vortex formation (topology, size) and mixing performance. The objective of this study is to test the ability of different fluid dynamic metrics in vortex detection and mixing effectiveness in micromixers. This is done numerically solving different conditions for the flow in a classic passive mixer, a ring shaped MC. We speculate that MCs design could take advantage from fluidic metrics able to rank properly flow related mixing

High-throughput microfluidic platform for adherent single cells non-viral gene delivery

The widespread use of gene therapy as a therapeutic tool relies on the development of DNA-carrying vehicles devoid of any safety concerns. In contrast to viral vectors, non-viral gene carriers show promise in this perspective, although their low transfection efficiency leads to the necessity to carry out further optimizations. In order to overcome the limitations of traditional macroscale approaches, which mainly consist of time-consuming and simplified models, a microfluidic strategy has been developed to carry out transfection studies on single cells in a high-throughput and deterministic fashion. A single cell trapping mechanism has been implemented, based on the dynamic variation of fluidic resistances. For this purpose, we designed a round-shaped culture chamber integrated with a bottom trapping junction, which modulates the hydraulic resistance. Several layouts of the chamber were designed and computationally validated for optimization of the single cell trapping efficacy. The optimized chamber layout was integrated in a polydimethylsiloxane (PDMS) microfluidic platform presenting two main functionalities: (i) 288 chambers for trapping single cells, and (ii) a serial dilution generator with chaotic mixing properties, able to deliver to the chambers both soluble factors and non-diffusive particles (i.e., polymer/DNA complexes, polyplexes) under spatio-temporally controlled chemical patterns. The devices were experimentally validated and allowed the trapping of individual human glioblastoma–astrocytoma epithelial-like cells (U87-MG) with a trapping efficacy of about 40%. The cells were cultured within the device and underwent preliminary transfection experiments using 25 kDa linear polyethylenimine (lPEI)-based polyplexes, confirming the potentiality of the proposed platform for the future high-throughput screening of gene delivery vectors and for the optimization of transfection protocols

Microfabricated polyester conical microwells for cell culture applications.

Over the past few years there has been a great deal of interest in reducing experimental systems to a lab-on-a-chip scale. There has been particular interest in conducting high-throughput screening studies using microscale devices, for example in stem cell research. Microwells have emerged as the structure of choice for such tests. Most manufacturing approaches for microwell fabrication are based on photolithography, soft lithography, and etching. However, some of these approaches require extensive equipment, lengthy fabrication process, and modifications to the existing microwell patterns are costly. Here we show a convenient, fast, and low-cost method for fabricating microwells for cell culture applications by laser ablation of a polyester film coated with silicone glue. Microwell diameter was controlled by adjusting the laser power and speed, and the well depth by stacking several layers of film. By using this setup, a device containing hundreds of microwells can be fabricated in a few minutes to analyze cell behavior. Murine embryonic stem cells and human hepatoblastoma cells were seeded in polyester microwells of different sizes and showed that after 9 days in culture cell aggregates were formed without a noticeable deleterious effect of the polyester film and glue. These results show that the polyester microwell platform may be useful for cell culture applications. The ease of fabrication adds to the appeal of this device as minimal technological skill and equipment is required