Development of a Portable Single Photon Ionization-Photoelectron Ionization Time-of-Flight Mass Spectrometer

A vacuum ultraviolet lamp based single photon ionization- (SPI-) photoelectron ionization (PEI) portable reflecting time-of-flight mass spectrometer (TOFMS) was designed for online monitoring gas samples. It has a dual mode ionization source: SPI for analyte with ionization energy (IE) below 10.6 eV and PEI for IE higher than 10.6 eV. Two kinds of sampling inlets, a capillary inlet and a membrane inlet, are utilized for high concentration and trace volatile organic compounds, respectively. A mass resolution of 1100 at m/z 64 has been obtained with a total size of 40 × 31 × 29 cm, the weight is 27 kg, and the power consumption is only 70 W. A mixture of benzene, toluene, and xylene (BTX), SO2, and discharging products of SF6 were used to test its performance, and the result showed that the limit of quantitation for BTX is as low as 5 ppbv (S/N = 10 : 1) with linear dynamic ranges greater than four orders of magnitude. The portable TOFMS was also evaluated by analyzing volatile organic compounds from wine and decomposition products of SF6 inside of a gas-insulated switchgear

Optimization of fluorescence in situ hybridization (FISH) for the identification of two polar coccoid green algae species

Standard FISH protocols using fluorochrome-labeled oligonucleotide probes have been successfully applied for in situ detection. However, optimized protocols of FISH for specific eukaryotes in marine environments are often not developed. This study optimized the conditions of fluorescence in situ hybridization(FISH) by using two polar isolated microalgae. The modified conditions were as follows: (1)10mg·mL-1 lysozyme solution pretreatment at 37°C for 30 min; (2)the hybridization buffer including 20% formamide; (3)the hybridization condition was 47°C for 6h. The cells enumerated by FISH were compared with those enumerated by flow cytometry(FCM) and DAPI to confirm the cell loss and hybridization efficiency. The optimized protocol was also successfully applied to Arctic Ocean samples, which were found to be dominated by Micromonas sp. The modified protocol showed a high relative efficiency and could be successfully applied for the detection of specific microbial eukaryotes in environmental samples

Quantitative security analysis of three-level unitary operations in quantum secret sharing without entanglement

Quantum secret sharing (QSS) protocols without entanglement have showed high security by virtue of the characteristics of quantum mechanics. However, it is still a challenge to compare the security of such protocols depending on quantitative security analysis. Based on our previous security analysis work on protocols using single qubits and two-level unitary operations, QSS protocols with single qutrits and three-level unitary operations are considered in this paper. Under the Bell-state attack we propose, the quantitative security analyses according to different three-level unitary operations are provided respectively in the one-step and two-step situations. Finally, important conclusions are drawn for designing and implementing such QSS protocols. The method and results may also contribute to analyze the security of other high-level quantum cryptography schemes based on unitary operations

UPRmt scales mitochondrial network expansion with protein synthesis via mitochondrial import [preprint]

As organisms develop, individual cells generate mitochondria to fulfill physiologic requirements. However, it remains unknown how mitochondrial network expansion is scaled to cell growth and impacted by environmental cues. The mitochondrial unfolded protein response (UPRmt) is a signaling pathway mediated by the transcription factor ATFS-1 which harbors a mitochondrial targeting sequence (MTS)1. Here, we demonstrate that ATFS-1 mediates an adaptable mitochondrial expansion program that is active throughout normal development. Developmental mitochondrial network expansion required the relatively inefficient MTS2 in ATFS-1, which allowed the transcription factor to be responsive to parameters that impact protein import capacity of the entire mitochondrial network. Increasing the strength of the ATFS-1 MTS impaired UPRmt activity throughout development due to increased accumulation within mitochondria. The insulin-like signaling-TORC13 and AMPK pathways affected UPRmt activation4,5 in a manner that correlated with protein synthesis. Manipulation to increase protein synthesis caused UPRmt activation. Alternatively, S6 kinase inhibition had the opposite effect due to increased mitochondrial accumulation of ATFS-1. However, ATFS-1 with a dysfunctional MTS6 constitutively increased UPRmt activity independent of TORC1 function. Lastly, expression of a single protein with a strong MTS, was sufficient to expand the muscle cell mitochondrial network in an ATFS-1-dependent manner. We propose that mitochondrial network expansion during development is an emergent property of the synthesis of highly expressed mitochondrial proteins that exclude ATFS-1 from mitochondrial import, causing UPRmt activation. Mitochondrial network expansion is attenuated once ATFS-1 can be imported

UPR(mt) scales mitochondrial network expansion with protein synthesis via mitochondrial import in Caenorhabditis elegans

As organisms develop, individual cells generate mitochondria to fulfill physiological requirements. However, it remains unknown how mitochondrial network expansion is scaled to cell growth. The mitochondrial unfolded protein response (UPR(mt)) is a signaling pathway mediated by the transcription factor ATFS-1 which harbors a mitochondrial targeting sequence (MTS). Here, using the model organism Caenorhabditis elegans we demonstrate that ATFS-1 mediates an adaptable mitochondrial network expansion program that is active throughout normal development. Mitochondrial network expansion requires the relatively inefficient MTS in ATFS-1, which allows the transcription factor to be responsive to parameters that impact protein import capacity of the mitochondrial network. Increasing the strength of the ATFS-1 MTS impairs UPR(mt) activity by increasing accumulation within mitochondria. Manipulations of TORC1 activity increase or decrease ATFS-1 activity in a manner that correlates with protein synthesis. Lastly, expression of mitochondrial-targeted GFP is sufficient to expand the muscle cell mitochondrial network in an ATFS-1-dependent manner. We propose that mitochondrial network expansion during development is an emergent property of the synthesis of highly expressed mitochondrial proteins that exclude ATFS-1 from mitochondrial import, causing UPR(mt) activation

Spatial Metrics of Interaction between CD163-Positive Macrophages and Cancer Cells and Progression-Free Survival in Chemo-Treated Breast Cancer

Tumor-associated macrophages (TAMs) promote progression of breast cancer and other solid malignancies via immunosuppressive, pro-angiogenic and pro-metastatic effects. Tumor-promoting TAMs tend to express M2-like macrophage markers, including CD163. Histopathological assessments suggest that the density of CD163-positive TAMs within the tumor microenvironment is associated with reduced efficacy of chemotherapy and unfavorable prognosis. However, previous analyses have required research-oriented pathologists to visually enumerate CD163+ TAMs, which is both laborious and subjective and hampers clinical implementation. Objective, operator-independent image analysis methods to quantify TAM-associated information are needed. In addition, since M2-like TAMs exert local effects on cancer cells through direct juxtacrine cell-to-cell interactions, paracrine signaling, and metabolic factors, we hypothesized that spatial metrics of adjacency of M2-like TAMs to breast cancer cells will have further information value. Immunofluorescence histo-cytometry of CD163+ TAMs was performed retrospectively on tumor microarrays of 443 cases of invasive breast cancer from patients who subsequently received adjuvant chemotherapy. An objective and automated algorithm was developed to phenotype CD163+ TAMs and calculate their density within the tumor stroma and derive several spatial metrics of interaction with cancer cells. Shorter progression-free survival was associated with a high density of CD163+ TAMs, shorter median cancer-to-CD163+ nearest neighbor distance, and a high number of either directly adjacent CD163+ TAMs (within juxtacrine proximity \u3c12 µm to cancer cells) or communicating CD163+ TAMs (within paracrine communication distance \u3c250 µm to cancer cells) after multivariable adjustment for clinical and pathological risk factors and correction for optimistic bias due to dichotomization

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Master'sMASTER OF ENGINEERIN