Diode Laser Microwave Induced Plasma Cavity Ringdown Spectrometer: Performance and Perspective

Recent studies combining an atmospheric-pressure plasma source (inductively coupled plasma or microwave induced plasma) with cavity ringdown spectroscopy (plasma-CRDS) have indicated significant promise for ultra-sensitive elemental measurements. Initial plasma-CRDS efforts employed an inductively coupled plasma as the atomization source and a pulsed laser system as the light source. In an effort to improve the portability and reduce the cost of the system for application purposes, we have modified our approach to include a compact microwave induced plasma and a continuous wave diode laser. A technique for controlling the coupling of the continuous wave laser to the ringdown cavity has been implemented using a standard power combiner. No acouto-optic modulator or cavity modulation is required. To test the system performance, diluted standard solutions of strontium (Sr) were introduced into the plasma by an in-house fabricated sampling device combined with an ultrasonic nebulizer. SrOH radicals were generated in the plasma and detected using both a pulsed laser system and a diode laser via a narrow band transition near 680 nm. The experimental results obtained using both light sources are compared and used for system characterization. The ringdown baseline noise and the detection limit for Sr are determined for the current experimental configuration. The results indicate that a plasma-CRDS instrument constructed using diode lasers and a compact microwave induced plasma can serve as a small, portable, and sensitive analytical tool. (C) 2004 American Institute of Physics

Optical clearing of laser-induced tissue plasma

We studied the effect of optical clearing (OC) by glycerol on laser-induced tissue plasma using the immersion method. The results demonstrated the apparently enhanced effect of glycerol on the molecular spectra of the laser induced plasma. The OC is more sensitive to the molecular bands than atomic lines. After tissue immersion in the glycerol, the electron density of tissue plasma is decreased. The laser plasma temperature of the glycerol treated tissue is higher than for virgin fresh tissue. The tissue plasma after the glycerol application is still in the local thermal equilibrium plasma state. This work presents a new perspective for OC application that can extend from tissue better imaging quality to improvement of laser plasma generation

Cationic Polystyrene Resolves Nonalcoholic Steatohepatitis, Obesity, and Metabolic Disorders by Promoting Eubiosis of Gut Microbiota and Decreasing Endotoxemia.

A pandemic of metabolic diseases, consisting of type 2 diabetes, nonalcoholic fatty liver disease, and obesity, has imposed critical challenges for societies worldwide, prompting investigation of underlying mechanisms and exploration of low-cost and effective treatment. In this report, we demonstrate that metabolic disorders in mice generated by feeding with a high-fat diet without dietary vitamin D can be prevented by oral administration of polycationic amine resin. Oral administration of cholestyramine, but not the control uncharged polystyrene, was able to sequester negatively charged bacterial endotoxin in the gut, leading to 1) reduced plasma endotoxin levels, 2) resolved systemic inflammation and hepatic steatohepatitis, and 3) improved insulin sensitivity. Gut dysbiosis, characterized as an increase of the phylum Firmicutes and a decrease of Bacteroidetes and Akkermansia muciniphila, was fully corrected by cholestyramine, indicating that the negatively charged components in the gut are critical for the dysbiosis. Furthermore, fecal bacteria transplant, derived from cholestyramine-treated animals, was sufficient to antagonize the metabolic disorders of the recipient mice. These results indicate that the negatively charged components produced by dysbiosis are critical for biogenesis of metabolic disorders and also show a potential application of cationic polystyrene to treat metabolic disorders through promoting gut eubiosis

Comparison and correlation study of polar biomarkers of CKD patients in saliva and serum by UPLC-ESI-MS

Abstract:There are abundant reports on the use of aromatic amino acids and creatinineas biomarkers in serum and urine forCKD(chronic kidney disease). However, investigationsinto these bio-species in bio-fluids, such as saliva and sweat, are rarely reported. Increasing interest in non-invasive methods for medical diagnosis advocates for the testing of these bio-fluidstoidentify potential biomarkers for prompt clinical andpreliminary screening using advanced analytical equipment.Unstimulated whole saliva samples were obtained from twenty-seven CKD patients and an equivalent number of healthy individuals. Saliva was assayed with ultra-performance liquid chromatography coupled with electro-spray ionization tandem mass spectrometry (UPLC-ESI-MS) in hydrophilic interaction chromatography mode. The data were analyzed using a student’s t test and receiver operatingcharacteristic(ROC) to evaluate the predictive power of several potential biomarkers (P<0.01) in saliva for preliminary CKD screening. Through testing of salivary samples between CKD patients and healthy individuals, we found three possible salivary biomarkers that demonstrated significant differences(P<0.01) from the nine reported species in serum and/or urine. The area under the curve (AUC) values for control vs CKDpatientsfor on L-phenylalanine, L- tryptophan, and creatinine were 0.863, 0.834, and 0.916, respectively. This is the first report to compare serum and urine biomarkers in saliva between CKD patients and healthy people. This study explores the potential of CKD diagnosis by saliva, and demonstrates a positive correlation between salivary and serum creatinine

Whole-genome resequencing of 472 Vitis accessions for grapevine diversity and demographic history analyses

Despite the importance of grapevine cultivation in human history and the economic values of cultivar improvement, large-scale genomic variation data are lacking. Here the authors resequence 472 Vitis accessions and use the identified genetic variations for domestication history, demography, and GWAS analyses

In-Depth Study on Propane-Air Combustion Enhancement With Dielectric Barrier Discharge

Low-temperature plasmas generated from dielectric barrier discharges (DBDs) play an important role in hydrocarbon combustion reactions. In this paper, two different arrangements of coaxial cylindrical DBD reactors are designed to investigate the enhancement processes of plasma-assisted propane combustion through activating propane and air, respectively. Each reactor corresponds to one kind of activation method. With plasma being on and off, the physical appearances of the propane combustion flame are observed and compared, and the spatial distributions of the flame temperature are measured and comparatively investigated under each activation approach. In addition, some major components such as OH, CH, and C-2 in the combustion flame are identified using flame/plasma emission spectroscopy. The relationship of OH radical concentration with flame position is studied when plasma is on and off, and concentration profiles as well as densities of these major components in the main combustion zone are qualitatively measured and analyzed. Possible physical and chemical reaction mechanisms in the plasma and flame zones are discussed in detail under both activation ways. Experimental results suggest that propane combustion be enhanced with plasma applied on either propane or air stream. A temperature rise of about 30 degrees C is achieved for the activation of propane, but about 50 degrees C is achieved for the activation of air with a 30-W plasma being applied. It denotes that some active species like O-atoms, N-atoms, and excited molecular oxygen and nitrogen produced by activating air components play a greater role than those smaller fragments and radicals generated by cracking propane in plasma-assisted combustion in our experimental conditions

Microplasma Technology and Its Applications in Analytical Chemistry

This review article describes some existing microplasma sources and their applications in analytical chemistry. These microplasmas mainly include direct current glow discharge (DC), microhollow-cathode discharge (MHCD) or microstructure electrode (MSE), dielectric barrier discharge (DBD), capacitively coupled microplasmas (CC mu Ps), miniature inductively coupled plasmas (mICPs), and microwave-induced plasmas (MIPs). The historical development and recent advances in these microplasma techniques are presented. Fundamental properties of the microplasmas, the unique features of the reduced size and volume, as well as the advantageous device structures for chemical analysis are discussed in detail, with the emphasis toward detection of gaseous samples. The analytical figures of merit obtained using these microplasmas as molecular/elemental-selective detectors for emission spectrometry and as ionization sources for mass spectrometry are also given in this review article

Ultra-Sensitive Elemental and Isotope Measurements with Compact Plasma Source Cavity Ring-Down Spectroscopy (CPS-CRDS)

The proposed research is to develop a new class of instruments for actinide isotopes and hazardous element analysis through coupling highly sensitive cavity ring-down spectroscopy to a compact microwave plasma source. The research work will combine advantages of CRDS measurement with a low power, low flow rate, tubing-type microwave plasma source to reach breakthrough sensitivity for elemental analysis and unique capability of isotope measurement. The project has several primary goals: (1) Explore the feasibility of marrying CRDS with a new microwave plasma source; (2) Provide quantitative evaluation of CMPCRDS for ultratrace elemental and actinide isotope analysis; (3) Approach a breakthrough detection limit of ca. 10-13 g/ml or so, which are orders of magnitude better than currently available best values; (4) Demonstrate the capability of CMP-CRDS technology for isobaric measurements, such as 238U and 238Pu isotopes. (5) Design and assemble the first compact, field portable CMP-CRDS instrument with a high-resolution diode laser for DOE/EM on-site demonstration. With all these unique capabilities and sensitivities, we expect CMP-CRDS will bring a revolutionary change in instrument design and development, and will have great impact and play critical roles in supporting DOE's missions in environmental remediation, environmental emission control, waste management and characterization, and decontamination and decommissioning. The ultimate goals of the proposed project are to contribute to environmental management activities that would decrease risk for the public and workers, increase worker productivity with on-site analysis, and tremendously reduce DOE/EM operating costs