A Micro-Analytical System for Complex Vapor Mixtures - Development and Application to Indoor Air Contaminants.

This dissertation concerns the development of two fully integrated, automatically controlled, field-deployable Si-microfabricated gas chromatograph (µGC) prototypes, and their application to indoor-air monitoring of trace-level trichloroethylene (TCE) vapor concentrations. Each µGC prototype has a pre-trap and a partially selective high-volume sampler of conventional design, a micromachined-Si focuser for injection, dual micromachined-Si columns for separation, and an integrated array of four microscale chemiresistors with functionalized gold-nanoparticle interface films for detection. Scrubbed ambient air is used as the carrier gas. Operating conditions and control settings are user-defined through a laptop computer, providing real-time data display and continuous unattended operation. A meso-scale GC employing the same detector technology as in the µGC prototypes was adapted for the same application, and the laboratory results obtained were used to guide the design and operating conditions of the µGCs. Application of a multivariate curve resolution method for deconvoluting microsensor array responses from partially overlapping interferences was also demonstrated. The µGC prototypes were characterized in the laboratory and then field tested in Utah in a house with active TCE vapor intrusion. In the laboratory, the separation of TCE from 45 other VOCs in < 60 sec, unique sensor-array response patterns, and accurate quantification of as little as 0.12 parts per billion (ppb) of TCE were demonstrated. In the field, the projected single-microsensor detection limit was 0.052 ppb for an 8-L air sample collected and analyzed in 20 min. Above the mitigation action level (MAL) of 2.3 ppb for the field-test site, accurate TCE determinations were achieved in the presence of up to 52 documented background VOCs. Below the MAL, positive biases were observed, which are attributable to background VOCs that were unresolvable chromatographically or by analysis of the sensor-array response patterns. Spatial and temporal variations in TCE concentrations, ranging from 0.23 to 56 ppb, provided by the prototypes were in good agreement with reference method values. This is the first study to validate the performance of a µGC in the field. Results demonstrate that µGC technology could provide selective, trace-level, on-site determinations of VOCs in numerous applications relevant to occupational and environmental exposure assessment.Ph.D.Environmental Health SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/91391/1/airbuff_1.pd

Scheduling of Multicast and Unicast Services under Limited Feedback by using Rateless Codes

Many opportunistic scheduling techniques are impractical because they require accurate channel state information (CSI) at the transmitter. In this paper, we investigate the scheduling of unicast and multicast services in a downlink network with a very limited amount of feedback information. Specifically, unicast users send imperfect (or no) CSI and infrequent acknowledgements (ACKs) to a base station, and multicast users only report infrequent ACKs to avoid feedback implosion. We consider the use of physical-layer rateless codes, which not only combats channel uncertainty, but also reduces the overhead of ACK feedback. A joint scheduling and power allocation scheme is developed to realize multiuser diversity gain for unicast service and multicast gain for multicast service. We prove that our scheme achieves a near-optimal throughput region. Our simulation results show that our scheme significantly improves the network throughput over schemes employing fixed-rate codes or using only unicast communications

Pseudogap and weak multifractality in disordered Mott charge-density-wave insulator

The competition, coexistence and cooperation of various orders in low-dimensional materials like spin, charge, topological orders and charge-density-wave has been one of the most intriguing issues in condensed matter physics. In particular, layered transition metal dichalcogenides provide an ideal platform for studying such an interplay with a notable case of 1${T}$-TaS$_{2}$ featuring Mott-insulating ground state, charge-density-wave, spin frustration and emerging superconductivity together. We investigated local electronic states of Se-substituted 1${T}$-TaS$_{2}$ by scanning tunneling microscopy/spectroscopy (STM/STS), where superconductivity emerges from the unique Mott-CDW state. Spatially resolved STS measurements reveal that an apparent V-shape pseudogap forms at the Fermi Level (E$_{F}$), with the origin of the electronic states splitting and transformation from the Mott states, and the CDW gaps are largely preserved. The formation of the pseudogap has little correlation to the variation of local Se concentration, but appears to be a global characteristics. Furthermore, the correlation length of local density of states (LDOS) diverges at the Fermi energy and decays rapidly at high energies. The spatial correlation shows a power-law decay close to the Fermi energy. Our statistics analysis of the LDOS indicates that our system exhibits weak multifractal behavior of the wave functions. These findings strongly support a correlated metallic state induced by disorder in our system, which provides an new insight into the novel mechanism of emerging superconductivity in the two-dimensional correlated electronic systems

Influence of cultivation parameters or supplement on product qualities and culture performances during perfusion

Perfusion processes have been developed with technological advances in single-use bioreactor and cell retention device. Perfusion has advantages such as high cell density culture in compact facilities and media change or culture parameter shifts for protein production with desired qualities. Single use bioreactor (200L or 1000L) with ATF System was used for the clinical production. For the process development, the scale-down model was established with lab-scale (2L) bioreactor with ATF2. A recombinant CHO cell line producing a fusion protein was cultivated using in-house serum-free media. Influence of insulin (0~3mg/L) on qualities was investigated in the established perfusion process using in-house serum-free medium and 2L scale-down model. The results showed that low concentration of insulin enhanced O-glycosylation and -2 charged N-glycan of fusion protein. Temperature (30~34oC) conditions, under no addition of insulin, were investigated to evaluate effect on qualities. High temperature enhanced O-glycosylation and -2 charged N-glycan of fusion protein. To evaluate interaction among culture parameters (Temperature, pH, and Dissolved Oxygen) in the perfusion process, Central Composite Inscribed (CCI) was selected as design of experiment. 20 perfusion cultures were carried out in the 2L scale-down model. The results showed each parameter and interactions among parameters had an effect on qualities and culture performances

Subacute Neurological Deterioration with Selective Axonal Injury in Patients with Acute Ischemic Stroke following Reperfusion of Middle Cerebral Artery Occlusion

To date, the long-term effects of reperfusion on the salvaged brain tissues have not been addressed in the literature. We report 4 cases presenting subacute neurological deteriorations with selective axonal injury following reperfusion therapies for acute ischemic stroke. Our case series based on 4 patients showed common features distinct from those of early reperfusion injury in that (1) the neurological symptoms developed after 1-2 months of reperfusion therapies, (2) these symptoms were accompanied by the subcortical white matter changes on brain MRI, and (3) these findings were mostly reversible with time. This suggests that axons in the reperfused brain may be vulnerable to further neurological injury

Microfabricated gas chromatograph for Sub-ppb determinations of TCE in vapor intrusion investigations

AbstractA microfabricated gas chromatograph (μGC) is described and its application to the analysis of sub-parts-per-billion (ppb) concentrations of trichloroethylene (TCE) in mixtures, relevant to the problem of TCE vapor intrusion (VI) into homes and offices, is demonstrated. The system employs a MEMS focuser, dual MEMS separation columns, and MEMS interconnects along with a microsensor array. These are interfaced to a (non-MEMS) front-end pre-trap and high-volume sampler module to reduce analysis time. The response patterns generated from the sensor array for each vapor are combined with the chromatographic retention time to identify and differentiate the components of VOC mixtures. All functions are controlled by a LabView routine written in house. A chemometric method based on multivariate curve resolution has also been developed for analyzing partially resolved mixture components. First results are presented of the capture, separation, recognition, and quantification of TCE in a mixture. TCE is measured at 0.185 ppb, with a projected detection limit of 0.030 ppb (20-L sample)

Proposal of Strength Formula and Type Development of Composite Mega Column to Beam Connections with T-shaped Stiffener

[EN] As buildings are becoming larger, demand for mega-sized composite columns (over 1-meter diameter) is increased. We have developed and commercialized welded built-up CFT column (ACT Column I) since 2005 which are structurally stable and economical using cold-formed steel with rib. However, there has a limit in size of cross section (618 X 618mm) by a fabrication facilities. And due to charateristics of closed cross section, there has a limit to construction of connection of moment frame. Composite mega column (ACT Column II) has same concept of forming closed cross section. But in order to enlarge cross sectional size, thick plate is inserted between cold-formed steels. Since composite mega column can control thickness and width of thick plate, steel or composite beams can be directly attached to the connection. In this study, we propose strength formula of composite mega column to beam connections with T-shaped stiffener as internal diaphragm and verified through finite element analysis and simple tensile experiment.Lee, JH.; Kim, SH.; Kim, BK.; Yom, KS.; Choi, SM. (2018). Proposal of Strength Formula and Type Development of Composite Mega Column to Beam Connections with T-shaped Stiffener. En Proceedings of the 12th International Conference on Advances in Steel-Concrete Composite Structures. ASCCS 2018. Editorial Universitat Politècnica de València. 465-473. https://doi.org/10.4995/ASCCS2018.2018.7016OCS46547

Alpha-tocopherol exerts protective function against the mucotoxicity of particulate matter in amphibian and human goblet cells

Exposure to particulate matter (PM) in ambient air is known to increase the risk of cardiovascular disorders and mortality. The cytotoxicity of PM is mainly due to the abnormal increase of reactive oxygen species (ROS), which damage cellular components such as DNA, RNA, and proteins. The correlation between PM exposure and human disorders, including mortality, is based on long-term exposure. In this study we have investigated acute responses of mucus-secreting goblet cells upon exposure to PM derived from a heavy diesel engine. To this end, we employed the mucociliary epithelium of amphibian embryos and human Calu-3 cells to examine PM mucotoxicity. Our data suggest that acute exposure to PM significantly impairs mucus secretion and results in the accumulation of mucus vesicles in the cytoplasm of goblet cells. RNA-seq analysis revealed that acute responses to PM exposure significantly altered gene expression patterns; however, known regulators of mucus production and the secretory pathway were not significantly altered. Interestingly, pretreatment with alpha-tocopherol nearly recovered the hyposecretion of mucus from both amphibian and human goblet cells. We believe this study demonstrates the mucotoxicity of PM and the protective function of alpha-tocopherol on mucotoxicity caused by acute PM exposure from heavy diesel engines