Short- and medium-term reproducibility of gastric emptying of a solid meal determined by a low dose of ^(13)C-octanoic acid and nondispersive isotope-selective infrared spectrometry

AIM： To evaluate the reproducibility of a modified 13^C breath test-based measurement of solid phase gastric emptying （GE） within the frames of a simple-repeated measure study protocol. METHODS： Twelve healthy subjects （6 females and 6 males, mean age 24.9＋0.7 years） were recruited to undergo three identical GE examinations. In six subjects the first two examinations were performed 2 d apart, and the third session was carried out at a median interval of 19.5 d （range 18 - 20 d） from the second one. In another six subjects the first two measurements were taken 20 d apart （median, range： 17-23 d）, whereas the third session took place 2 d after the second one. Probes of expiratory air collected before and during six hours after intake of a solid meal （378 kcal） labelled with 75 μL （68 mg） 13^C-octanoic acid, were measured for 13^CO2 enrichment with the nondispersive isotopeselective infrared spectrometry NDIRS apparatus. RESULTS： Taking coefficients of variation for paired examinations into account, the short-term reproducibility of the GE measurement was slightly but not significantly better than the medium-term one： 7.7% and 11.2% for the lag phase （T-Lag）, 7.3% and 10.9% for the gastric half emptying time （T1/2）. The least differences in GE parameters detectable at P= 0.05 level in the 12 paired examinations were 9.6 and 15.6 min for T-Lag, 11.6 and 19.7 min for T1/2 by a two-day or two to three-week time gap, respectively CONCLUSION： The low-cost modification of the breath test involving a lower dose of 13^C-octanoic acid and NDIRS, renders good short- and medium-term reproducibility, as well as sensitivity of the measurement of gastric emptying of solids.

Structure analysis of optical fiber coupler with infrared spectrometry

To obtain excellent performance optical fiber couplers, the structural difference of SiO2 in couplers with different manufacturing techniques was investigated. With 740-FT-IR infrared spectrometric analyzer, the infrared absorption spectrum of SiO2 in couplers at different drawing velocities was measured, and two characteristic peaks in the wavenumber range of 6502000 cm-1 were observed. One characteristic peak is at about 943 cm-1, which is （attributed） to Si—O—Si bond asymmetric stretching vibration, the other is at about 773 cm-1, which is attributed to （Si—O—Si） bond symmetric stretching vibration. From the infrared spectrum, it is found that the intensity and wavenumber of the characteristic peaks are related to the manufacturing technique of couplers. The characteristic peak at （about） 943 cm-1 becomes steeper when increasing the drawing velocity. At the drawing velocity of 150 μm/s, the distance between the two characteristic peaks is maximum, and then the optical fiber coupler has excellent performance, indicating that the performance of the optical fiber coupler has a close relationship with the wavenumber of the two characteristic peaks.

Application of a novel detection approach based on non-dispersive infrared theory to the in-situ analysis on indicator gases from underground coal fire

Coal mine fires,which can cause heavy casualties,environmental damages and a waste of coal resources,have become a worldwide problem.Aiming at overcoming the drawbacks,such as a low analysis efficiency,poor stability and large monitoring error,of the existing underground coal fire monitoring technology,a novel monitoring system based on non-dispersive infrared(NDIR)spectroscopy is developed.In this study,first,the measurement principle of NDIR sensor,the gas concentration calculation and its temperature compensation algorithms were expounded.Next,taking CO and CH_(4) as examples,the liner correlation coefficients of absorbance and the temperature correction factors of the two indicator gases were calculated,and then the errors of concentration measurement for CO,CO_(2),CH_(4) and C_(2)H_(4) were further analyzed.The results disclose that the designed NDIR sensors can satisfy the requirements of industrial standards for monitoring the indicator gases for coal fire hazards.For the established NDIR-based monitoring system,the NDIRbased spectrum analyzer and its auxiliary equipment boast intrinsically safe and explosion-proof performances and can achieve real-time and in-situ detection of indicator gases when installed close to the coal fire risk area underground.Furthermore,a field application of the NDIR-based monitoring system in a coal mine shows that the NDIR-based spectrum analyzer has a permissible difference from the chromatography in measuring the concentrations of various indicator gases.Besides,the advantages of high accuracy,quick analysis and excellent security of the NDIR-based monitoring system have promoted its application in many coal mines.

Adsorbability of Mycobacterium phlei on hematite surface

The adsorption of microorganisms on the mineral surface is the base of microorganisms that are considered as mineral processing reagents. The principles of the use of a highly hydrophobic and negatively charged bacterium, Mycobacterium phlei, as a flocculating-flotating agent for finely divided hematite were investigated. The flocculating-floating recovery is strongly dependent on the pH and the dosage of the bacterium. Generally the pH should be controlled over the range of 5.5-7, and the dosage should be controlled about 16 mg/L. The infrared spectrometry analysis indicates that the six functional groups of M. phlei, substituted aromatic compound groups, -（CH2） n-groups, -CH2（-CH3） groups, carbonyl groups, aromatic hydrocarbon groups, and carboxyl groups, are on the hematite surface, among which the first five ones contribute physical adsorption and only the carboxyl groups provide chemisorption. Microscopic analysis reveals that the dimensions and tight aggregation degree of the flocs of hematite particles formed by M. phlei are also impacted by the pH and the content of M. phlei in flotation.

Characterization of Protein in Old Myocardial Infarction by FTIR Micro-spectroscopy

The aim of the present study was to assess whether Fourier transform infrared spectrometry (FTIR) micro-spectroscopy could produce distinct spectral information on protein of old myocardial infarction (OMI) and to set them as molecular markers to diagnose atypical OMI. Paraffin-embedded heart samples were derived from victims dying of OMI. In combination with histological stain, FTIR and infrared micro-spectroscopy, the characteristics of OMI were analyzed morphologically and molecularly. The most relevant bands identified were the amide A, B, Ⅰ and Ⅱ, showing crucial spectral differences between apparent normal region and OMI region, including the peak position blue shift and the increased intensity of OMI, moreover relative increase in α-helix and decrease in β-sheet of protein secondary structures in OMI. Comparing to single spectral band, the I1650/I1550 ratio was increased and rationally used as a molecular marker for diagnosing OMI. These novel preliminary findings supported further exploration of FTIR molecular profiling in clinical or forensic study, and were in accordance with histopathology.

Effects of Solvents on Extraction of Effective Components from Cell Wall Tissues of Chinese Traditional Medicines

The effects of different Chinese traditional medicines were solvents on the extraction of effective studied by the histochemical methods, components from the cell wall tissues of such as the bare-handed section, swelling ratio, paraffin section, IR spectrum and cell wall component analysis. The results show that the ethanol-alkali solvent could increase the swelling ratio as well as the swelling speed. The effective components of cell wall tissues extracted by ethanol-alkali solvent become loose shown by the paraffin section. According to the IR spectrum analysis and the results of cell wall tissue component analysis, it was found that the ethanol-alkali solvent could decrease the contents of pectin and hemicellulose in the cell wall to make the wall broken, and therefore the effective components can be extracted easily by the solvent and the extraction rate is increased.

A quantum cascade laser infrared spectrometer for CO_2 stable isotope analysis：Field implementation at a hydrocarbon contaminated site under bio-remediation

Real-time methods to monitor stable isotope ratios of CO_2 are needed to identify biogeochemical origins of CO_2 emissions from the soil–air interface. An isotope ratio infra-red spectrometer（IRIS） has been developed to measure CO_2 mixing ratio with δ~13C isotopic signature, in addition to mixing ratios of other greenhouse gases（CH_4, N2_O）. The original aspects of the instrument as well as its precision and accuracy for the determination of the isotopic signature δ~13C of CO_2 are discussed. A first application to biodegradation of hydrocarbons is presented, tested on a hydrocarbon contaminated site under aerobic bio-treatment. CO_2 flux measurements using closed chamber method is combined with the determination of the isotopic signature δ~13C of the CO_2 emission to propose a non-intrusive method to monitor in situ biodegradation of hydrocarbons. In the contaminated area, high CO_2 emissions have been measured with an isotopic signature δ~13C suggesting that CO_2 comes from petroleum hydrocarbon biodegradation.This first field implementation shows that rapid and accurate measurement of isotopic signature of CO_2 emissions is particularly useful in assessing the contribution of contaminant degradation to the measured CO_2 efflux and is promising as a monitoring tool for aerobic bio-treatment.

Pyrolysis characteristics of Radix Rhizoma Rhei, Cortex Moudan Radicis, and Radix Sanguisorbae and correlations with the carbonizing process of Chinese herbs

AIM： The aim of the work is to study the pyrolysis characteristics of Radix Rhizoma Rhei, Cortex Moudan Radicis, and Radix Sanguisorbae in an inert atmosphere of argon （Ar）, and to investigate the mechanism of the carbonizing process of the three traditional Chinese herbs. METHODS： The pyrolysis characteristics of the crude materials and their extracts were studied by thermogravimetry-mass spectrometry （TG-MS） in a carrier gas of argon, coupled with Fourier transform infrared spectrometry （FTIR） and scanning electron microscopy （SEM） methods. Correlation of the pyrolysis behaviors with the carbonizing process by stir-frying of traditional Chinese medicines was made. RESULTS： Within the temperature range of 200-300 ℃, which is the testing range for the study of the carbonizing process of Chinese herbs, the temperatures indicated by the maximum weight loss rate peak of the above three extracts were taken as the upper-limit temperatures of the carbonizing process of the herbs, and which were 200, 240 and 247 ℃ for Radix Rhizoma Rhei, Cortex Moudan Radicis, and Radix Sanguisorbae, respectively. The ion monitoring signal peaks detected by the TG-MS method corresponded with reports that the level of chemical components of traditional Chinese medicinal materials would decrease after the carbonizing process. It was confirmed by Fourier transform infrared spectrometry （FTIR） and scanning electron microscopy （SEM） methods that better results of ＂medicinal property preservation＂ could be obtained by heating at 200 ℃ for Radix Rhizoma Rhei, at about 250 ℃ for Cortex Moudan Radicis, and Radix Sanguisorbae, as the relative intensity values of the common peaks were among the middle of their three carbonized samples by programmed heating. CONCLUSION： The upper-limit temperatures of the carbonizing process for Radix Rhizoma Rhei, Cortex Moudan Radicis and Radix Sanguisorbae were 200, 240 and 247 ℃ respectively. It is feasible to research the mechanism and technology of the carbonizing process of traditional Chinese medicinal materials using thermogravimetry, Fourier transform infrared spectrometry, and scanning electron microscopy methods.

Methodological progress in trace amounts of structural water in nominally anhydrous minerals

In the deep Earth, hydrogen mainly occurs as structural hydroxyl and molecular water in minerals and melts, constituting mobile and immobile aqueous components. Hydrous minerals contain hydrogen which occupies a specific structural position and constitutes an indispensable component of chemical formulae. On the other hand, nominally anhydrous minerals do not contain hydrogen in their chemical formulae, but can host trace amounts of water in structural position and lattice defect. The molecular water may occur in the lattice defect as fluid/melt inclusions in minerals. Even though the water content of nominally anhydrous minerals is very limited generally in the order of ppm(parts per million), they may play a significant role in influencing the physicochemical properties of mineral and rock systems. With the continuous improvement of modern instrumentations, the analytical methodology exhibits trends for higher spatial resolution, lower detection limit and integral multiple methods on the water amount and its isotopic ratio. Among these methods, Fourier transform infrared spectrometry remains the most widely used, while secondary ion mass spectrometry, continuous flow mass spectrometry, elastic recoil detection analysis and Raman spectrometry are promising. This paper provides a brief review on the methodological progress and their applications to the analysis of structural water in nominally anhydrous minerals.

Processing of Calamine with Modern Analytical Techniques:Processed with Huanglian Decoction(黄连汤)and Sanhuang Decoction(三黄汤)

Objective： To determine the pyrolysis characteristics of calcined and processed calamine, qualitatively and quantitatively compare the contents of related elements, morphology and functional groups of the pyrolysis products dried at different heating temperatures and explore the critical temperature and the optimal drying temperature for the process of calamine with Huanglian Decoction（HLD, 黄连汤） and San Huang Decoction（SHD, 三黄汤）. Methods： Pyrolysis products were prepared by programmable and constantly heating the calcined and processed calamine to or at different heating temperatures. Thermogravimetry（TG） was used to test their pyrolysis characteristics. Fourier transform infrared spectroscopy and scanning electron microscopeenergy dispersive spectrometer were used to determine their morphology, functional groups and element contents. Page model was used to investigate the constant drying kinetics of processed calamine. Results： The adding of HLD or SHD to calcined calamine（CC） can slow its weight loss in drying pyrolysis process. The temperature ranges where HLD and SHD can affect its weight loss were 65–150 ℃ and 74–180 ℃, respectively. The drying temperature was optimized as 90 ℃. The drying kinetic for the processed calamine fits Page model shows good linearity. Conclusions： The critical temperature and the optimal drying temperature where HLD and SHD can affect the weight loss rate in the process of calamine were explored using the theories and methods of both biophysical chemistry and processing of Chinese materia medica. This work provides a good example for the study of the process of other Chinese medicines using modern analytical techniques.

Reaction Mechanism of H2-Assisted C3H6-SCR over Ag-CexZr Catalyst as Investigated by In situ FTIR

A series of silver-doped cerium zirconium oxide(Ag-CevZr)samples was synthesized successfully for selective catalytic reduction of nitric oxide(NO)with hydrogen and propene(H2/C3H6-SCR)under excess oxygen condition.The catalytic activity test proved that Ag-Ce0.4Zr exhibited the best C3H6-SCR activity.Hydrogen(H2)significantly enlianced NO conversion and widened the temperature window.Multi-technology characterizations were conducted to ascertain the properties of fabricated catalysts including X-ray diflraction(XRD),Fourier transform infrared spectrometry(FTIR),scanning electron microscopy(SEM)and H2 temperature programmed reduction(H2-TPR).In situ FTIR results demonstrated that various types of nitrates and chelating nitrite were generated on Ag-CexZr after introduction of NO.Besides,adding H2 could increase the concentration of bidentate nitrate and chelated bidentate nitrate dramatically,especially for Ce0.4Zr catalyst.Transient reaction between pre-adsorbing NO and C3H/C3H6+H2 illuminated that the most active intermediate was chelating nitrite,which was promoted significantly by H2 participation.Furthermore,adding H2 improved the formation of organo-nitro(R-N02),which was the key intennediate in C3H6-SCR.The reaction mechanism over Ag-CexZr catalysts was proposed at 200℃ as follows:nitric oxide(NO)+pr opene(C 3H6)+hy dr ogen(H2)+oxy gen(O2)→chelating nitrite (N O2-)+acry late-type species(CxHyOz)→organo-nitro(R-NO2)→isocyanate(-NCO)+cyanide(—CN)→nitrogen(N2).

Crosslinking of PVA Pervaporation Membrane by Maleic Acid

Maleic acid (MA) crosslinked polyvinyl alcohol (PVA) membrane is prepared using a high temperature esterification reaction between PVA and MA in the presence of sulfuric acid as a catalyst. The crosslinking reaction mechanism is investigated using FT IR spectral analysis. The results indicate that maleic acid reacts with hydroxyl groups in PVA to form mono and bis ester in a two step process.