Determination of H2O and CO2 concentrations in fluid inclusions in minerals using laser decrepitation and capacitance manometer analysis

Water and carbon dioxide concentrations within individual and selected groups of fluid inclusions in quartz were analyzed by using laser decrepitation and quantitative capacitance manometer determination. The useful limit of detection (calculated as ten times the typical background level) is about 5 x 10(-10) mol of H2O and 5 x 10(-11) mol of CO2; this H2O content translates into an aqueous fluid inclusion approximately 25 micrometers in diameter. CO2/H2O determinations for 38 samples (100 separate measurements) have a range of H2O amounts of 5.119 x 10(-9) to 1.261 x 10(-7) mol; CO2 amounts of 7.216 x 10(-10) to 1.488 x 10(-8) mol, and CO2/H2O mole ratios of 0.011 to 1.241. Replicate mole ratio determinations of CO2/H2O for three identical (?) clusters of inclusions in quartz have average mole ratios of 0.0305 +/- 0.0041 1 sigma. Our method offers much promise for analysis of individual fluid inclusions, is sensitive, is selective when the laser energy is not so great as to melt the mineral (laser pits approximately 50 micrometers in diameter), and permits rapid analysis (approximately 1 h per sample analysis).     

Mechanically activated minerals as a sink for CO2

CO₂ removal from exhaust gasses from burning of fossil fuels is a political issue. If undertaken on a large scale, enormous amounts of carbon dioxide will have to be taken care of. This paper investigates how mechanical activation of olivine and other Ca or Mg containing silicates can increase the mineral’s reactivity. Tests by grinding in a planetary mill have been done to investigate the effects of mechanical activation and other surface changes. The reactivity towards HCl and CO₂ has been determined as a function of grinding variables. Prolonged dry milling of olivine resulted in highly aggregated products, which were more reactive with respect to dissolution in acid than their respective BET surface areas would suggest. The initial breaking of bonds appears to give more reactivity on an energy usage basis than longer time activation. Most mechanical activation testwork so far has been carried out in batch mode. The result is diminishing effect of activation with increased grinding time. Continuous grinding and simultaneous reaction with some sort of classification may offer a chance of removing reaction products as soon as they are formed, giving a more energy effective process.     

Ultrasonic densimeter for liquids

Translated from Izmeritel'naya Tekhnika, No. 3, pp. 44–45, March, 1993.     

Near-infrared spectroscopic determination of salinity and internal pressure of fluid inclusions in minerals

A near-infrared (NIR) spectroscopic method is proposed to achieve the simultaneous determination of salinity and internal pressure of fluid inclusions in natural minerals. A combination band between the anti-symmetric stretching and bending vibrations of molecular water at approximately 5180 cm-1 was observed for standard salt solutions and natural minerals containing fluid inclusions with known salinities. A curve-fitting procedure was used to analyze the change in the band shape of the combination. Justification of the calibration was confirmed by observation of fluid inclusions in natural minerals whose salinities had already been determined using microthermometry. The detection limit of the present method is 1 NaCl-eq wt. %. The minimum size of fluid inclusions that produced well-resolved spectra was approximately 30 microm. This method was applied to assess micro fluid inclusions in a natural diamond with cubic growth habit (cuboid). The salinity and residual pressure of those fluid inclusions were estimated respectively as 4.4 wt. % NaCl-eq and 0.6-0.8 GPa. The present method is complementary to Raman microscopy and microthermometry for the determination of salinity in fluid inclusions of geological samples.     

Development of a microwave-type densimeter for slush hydrogen

Slush hydrogen is a two-phase solid–liquid cryogenic fluid consisting of solid hydrogen particles in liquid hydrogen, various applications for which are anticipated, including fuel for reusable space shuttles. The authors of the current study have measured the density of slush hydrogen by using the phase shift that takes place when microwaves are propagated through slush hydrogen, i.e., using the change in the specific dielectric constant. This new technique, unlike the conventional method using a waveguide and horn antenna, features a coaxial cable and patch antenna that can be used at cryogenic temperatures, leading to the development of a slush hydrogen densimeter with a high accuracy of within ±0.5%.     

A vibrating-wire densimeter for measurements in fluids at high pressures

The paper describes a new type of densimeter especially designed for the accurate measurement of fluid densities at pressures up to 400 MPa. The densimeter makes use of the buoyancy force exerted on a mass immersed in the test fluid to alter the resonant frequency of a thin wire from which the mass is suspended. The resonant frequency of the wire carrying the mass is related to the fluid density by means of working equations which are based on a complete analysis of the fluid motion around the wire. Preliminary results are presented for n-octane at pressures up to about 100 MPa near ambient temperature. The results show that the instrument has a precision of ±0.1 % in density at elevated pressures when evaluated on a relative basis, while the accuracy is estimated to be one of ±0.2%.     

A vibrating-tube densimeter for fluids at high pressures and temperatures

A vibrating U-tube apparatus has been developed for determining the densities of pure fluids and fluid mixtures at 10-200 MPa and 323-773 K. Measured parameters areP,T, andr (period of vibration). Fluids are injected into the U-tube at constantP andT. Three or more reference fluids are used to calibrate the response of the instrument. Fluid mixtures are produced by pumping pure fluids into T-junctions on the upstream side of the U-tube using high accuracy syringe pumps. An automated syringe pump is used to maintainP at setpoint ±0.01 MPa.T is controlled to ±0.01 K using a closed-loop, electronic signal amplification/feedback system. For mixtures, a statistically significant number of measurements of r are obtained to account for the effects of small heterogeneities in fluid composition (generally <0.005X;). Typically, density data for 15 fluids can be obtained in a 6- to 8-h period. Considering all of the potential sources of error in the experimentation, conservative estimates of uncertainty are as follows:P, ±0.02 MPa;T, ±0.05 K;p (pure fluids), ±0.0005g.cm^–3; andp (fluid mixtures), ±0.0005-0.0010g-cm^–3.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994, Boulder, Colorado, U.S.A.     

Photocatalyzing CO2 to CO for Enhanced Cancer Therapy

Continuous exposure to carbon monoxide (CO) can sensitize cancer cells to chemotherapy while protect normal cells from apoptosis. The Janus face of CO thus provides an ideal strategy for cancer therapy. Here, a photocatalytic nanomaterial (HisAgCCN) is introduced to transform endogenous CO₂ to CO for improving cancer therapy in vivo. The CO production rate of HisAgCCN reaches to 65 µmol h^?1 g_mat^?1, which can significantly increase the cytotoxicity of anticancer drug (doxorubicin, DOX) by 70%. Interestingly, this study finds that HisAgCCN can enhance mitochondria biogenesis and aggravate oxidative stress in cancer cells, whereas protect normal cells from chemotherapy‐induced apoptosis as well. Proteomics and metabolomics studies reveal that HisAgCCN can enhance mitochondria biogenesis and aggravate oxidative stress in cancer cells specifically. In vivo studies indicate that HisAgCCN/DOX combination therapy presents a synergetic tumor inhibition, which might provide a new direction for clinical cancer therapy.     

Rechargeable Al–CO2 Batteries for Reversible Utilization of CO2

The excessive emission of CO₂ and the energy crisis are two major issues facing humanity. Thus, the electrochemical reduction of CO₂ and its utilization in metal–CO₂ batteries have attracted wide attention because the batteries can simultaneously accelerate CO₂ fixation/utilization and energy storage/release. Here, rechargeable Al–CO₂ batteries are proposed and realized, which use chemically stable Al as the anode. The batteries display small discharge/charge voltage gaps down to 0.091 V and high energy efficiencies up to 87.7%, indicating an efficient battery performance. Their chemical reaction mechanism to produce the performance is revealed to be 4Al + 9CO₂ ? 2Al₂(CO₃)₃ + 3C, by which CO₂ is reversibly utilized. These batteries are envisaged to effectively and safely serve as a potential CO₂ fixation/utilization strategy with stable Al.     

Nanorattle Au@PtAg encapsulated in ZIF-8 for enhancing CO2 photoreduction to CO

Nano Research - Imidazolate-based ZIF-8 catalysts M@ZIF-8 (M = Au NR, Au@Ag NR, or Au@PtAg NRT; NR = nanorod, NRT = nanorattle), were assembled. Au NRs acted as the core for the epitaxial growth of...     

Promoting CO2 Dynamic Activation via Micro-Engineering Technology for Enhancing Electrochemical CO2 Reduction

Optimizing the coordination structure and microscopic reaction environment of isolated metal sites is promising for boosting catalytic activity for electrocatalytic CO₂ reduction reaction (CO₂RR) but is still challenging to achieve. Herein, a newly electrostatic induced self-assembly strategy for encapsulating isolated Ni-C₃N₁ moiety into hollow nano-reactor as I-Ni SA/NHCRs is developed, which achieves FE_CO of 94.91% at −0.80 V, the CO partial current density of ≈−15.35 mA cm⁻², superior to that with outer Ni-C₂N₂ moiety (94.47%, ≈−12.06 mA cm⁻²), or without hollow structure (92.30%, ≈−5.39 mA cm⁻²), and high FE_CO of ≈98.41% at 100 mA cm⁻² in flow cell. COMSOL multiphysics finite-element method and density functional theory (DFT) calculation illustrate that the excellent activity for I-Ni SA/NHCRs should be attributed to the structure-enhanced kinetics process caused by its hollow nano-reactor structure and unique Ni-C₃N₁ moiety, which can enrich electron on Ni sites and positively shift d-band center to the Fermi level to accelerate the adsorption and activation of CO₂ molecule and *COOH formation. Meanwhile, this strategy also successfully steers the design of encapsulating isolated iron and cobalt sites into nano-reactor, while I-Ni SA/NHCRs-based zinc-CO₂ battery assembled with a peak power density of 2.54 mW cm−⁻² is achieved.     

Micro-Raman spectroscopy for optical pathology of oral squamous cell carcinoma

Micro-Raman spectra of formalin-fixed oral squamous normal and carcinoma tissues, stored at room temperature for 2 months, have been recorded. Spectra were recorded both in the epithelial and subepithelial regions of the tissues. No noticeable spectral contamination due to formalin was observed. Very significant differences between spectra of normal epithelial and malignant epithelial samples were found. No such differences in spectra of subepithelial malignant and subepithelial normal samples could be observed. This study shows that spectra from the epithelial region changes drastically because of malignancy-induced biochemical changes in this region. Major differences between normal and malignant spectra seem to arise from the protein composition, conformational/structural changes, and possible increase in protein content in malignant epithelia. The differences between normal epithelial and subepithelial spectra, as expected, arise mainly from the collagen in subepithelial tissue. Principal component analysis of the combined sets of spectra-epithelial and subepithelial, normal and malignant- showed that very good discrimination can be achieved by Raman microspectroscopy. This study thus validates the suitability of formalin-fixed tissues for optical pathology in oral malignancy.     

CO2 Nanoenrichment and Nanoconfinement in Cage of Imine Covalent Organic Frameworks for High‐Performance CO2 Cathodes in Li‐CO2 Batteries

The Li‐CO₂ battery is an emerging green energy technology coupling CO₂ capture and conversion. The main drawback of present Li‐CO₂ batteries is serious polarization and poor cycling caused by random deposition of lithium ions and big insulated Li₂CO₃ formation on the cathode during discharge. Herein, covalent organic frameworks (COF) are identified as the porous catalyst in the cathode of Li‐CO₂ batteries for the first time. Graphene@COF is fabricated, graphene with thin and uniform imine COF loading, to enrich and confine CO₂ in the nanospaces of micropores. The discharge voltage is raised by higher local CO₂ concentration, which is predicted by the Nernst equation and realized by CO₂ nanoenrichment. Moreover, uniform lithium ion deposition directed by the graphene@COF nanoconfined CO₂ can produce smaller Li₂CO₃ particles, leading to easier Li₂CO₃ decomposition and thus lower charge voltage. The graphene@COF cathode with 47.5% carbon content achieves a discharge capacity of 27833 mAh g^?1 at 75 mA g^?1, while retaining a low charge potential of 3.5 V at 0.5 A g^?1 for 56 cycles.     

Covalent Organic Frameworks for CO2 Capture

As an emerging class of porous crystalline materials, covalent organic frameworks (COFs) are excellent candidates for various applications. In particular, they can serve as ideal platforms for capturing CO₂ to mitigate the dilemma caused by the greenhouse effect. Recent research achievements using COFs for CO₂ capture are highlighted. A background overview is provided, consisting of a brief statement on the current CO₂ issue, a summary of representative materials utilized for CO₂ capture, and an introduction to COFs. Research progresses on: i) experimental CO₂ capture using different COFs synthesized based on different covalent bond formations, and ii) computational simulation results of such porous materials on CO₂ capture are summarized. Based on these experimental and theoretical studies, careful analyses and discussions in terms of the COF stability, low‐ and high‐pressure CO₂ uptake, CO₂ selectivity, breakthrough performance, and CO₂ capture conditions are provided. Finally, a perspective and conclusion section of COFs for CO₂ capture is presented. Recent advancements in the field are highlighted and the strategies and principals involved are discussed.     

分离CO2的促进传递膜

促进传递膜在分离机制上有别于普通分离膜，由于透过组分与膜中载体之间特异性的可逆反应使其性能优异．文章综述了国内外近年来在分离CO2促进传递膜方面的研究进展，特别介绍了本课题组在固定载体膜方面的研究结果，选择、研制固定工体膜材料所遵循的基本思路，以及对固定地体膜内传递机理所做的一些新探索．     

Polarization-characteristic determination for multichannel CO2 lasers

Polarization characteristics can be measured for engineering CO₂ lasers by means of an instrument consisting of two rigidly fixed insulating plates combined with radiation detectors, which are placed in such a way that the planes of incidence form an angle of 90°. The plates with detectors rotate around the propagation direction in a cyclic fashion. The main flux passes through the plates, and only the reflected paris of the beam are used in the recording. The radiation prom an LN-1,2, NM-I1 laser is partially or completely polarized for about 70–80% of the time of operation. During the rest of the time, the radiation is unpolarized or there is an ongoing change in the orientation of the polarization plane. All the channels are at least partially synchronized in polarization characteristics.Translated from Izmeritel'naya Tekhnika, No. 7, pp. 25–27, July, 1993.