Analysis of variable mass diffusivity in Maxwell's fluid with Cattaneo-Christov and nonlinear stratification.

This investigation consists of Maxwell's fluid which describes rate type non-Newtonian fluid in best; it has great applications in engineering, technology and industry. Linear stretching sheet generates the flow in fluid. Flow momentum is measured with MHD effect. When Fourier's and Fick's laws are incorporated relaxation time factor then known as Cattaneo-Christov model which are implemented for heat and mass transport. The features of heat source or sink and non-linear type thermal stratification are employed with variable thermal conductivity. The features of chemical reaction and non-linear type solutal stratification are analyzed along with variable mass diffusivity. By the usage of boundary layer phenomenality in this problem, non-linear PDEs are achieved. These equations are transmuted into non-linear and non-homogeneous differential equations ramified with ordinary derivatives after applying similarity transformations. The most exclusive homotopic analysis method is used to get the analytic solutions of nonlinear and non-dimensional governing equations. The significant results of progressive parameters are dominant in this investigation. The arising parameters are examined in detail and results are shown graphically. It is found out that with the increment of time relaxation factor velocity, temperature and concentration profiles reduce. It increases the viscoelastic impacts related to stress relaxation time which makes viscoelastic materials more durable.

Advances in carbon isotope analysis of trapped methane and volatile hydrocarbons in crystalline rock cores.

RATIONALE: The isotopic composition of hydrocarbons trapped in rocks on the microscale (fluid inclusions, mineral grain boundaries, microfractures) can provide powerful information on geological and biological processes but are an analytical challenge due to low concentrations. We present a new approach for the extraction and carbon isotopic analysis of methane (CH4 ) and hydrocarbons in trapped volatiles in crystalline rocks. METHODS: An off-line crusher with cryogenic trapping and a custom-made silica glass U-trap were attached to an external injector port on a continuous flow gas chromatograph/combustion/isotope ratio mass spectrometer to demonstrate the accuracy, reproducibility, and sensitivity of δ13 C measurements for CH4 . RESULTS: The method can isotopically characterize CH4 in crushed rock samples with concentrations as low as 3.5 × 10-9 mol/g of rock, and both sample and isotopic standards are analyzed with an accuracy and reproducibility of ±0.5‰. High H2 O/CH4 ratios of 98 to 500 have no effect on measured δ13 CCH4 values. The method is successfully applied to natural samples from the north range of Sudbury Basin, Ontario, Canada. The δ13 C isotopic signatures of CH4 trapped microscopically in rock from the north range overlap significantly with that of CH4 contained in larger scale flowing fracture fluids from the same part of the Sudbury Basin, indicating a potential genetic link. CONCLUSIONS: A novel method for δ13 CCH4 analysis was developed for the extraction of nanomole quantities of CH4 trapped microscopically in rocks. The technique has an accuracy and reproducibility comparable to that of on-line crushing techniques but importantly provides the capability of crushing larger rock quantities (up to 100 g). The benefit is improved detection levels for trace hydrocarbon species. Such a capability will be important for future extension of such crushing techniques for measurement of 2 H/1 H for CH4 , clumped isotopologues of CH4 and other trapped volatiles species, such as C2 H6 , C3 H8 , C4 H10 , CO2 and N2 .

Coupled Si and O isotope measurements of meteoritic material by laser fluorination isotope ratio mass spectrometry.

We present a procedure for the determination of the isotopic ratios of silicon and oxygen from the same aliquot of anhydrous silicate material. The sample is placed in a bromine pentafluoride atmosphere as it is heated with a CO2 laser system releasing silicon tetrafluoride and oxygen gasses. The oxygen gas is then purified to remove other reaction by-products through several liquid nitrogen traps before being captured onto a molecular sieve and transferred to an isotope ratio mass spectrometer. The silicon tetrafluoride gas is then purified using a supplementary line by repeatedly freezing to -196°C with liquid nitrogen and then thawing with an ethanol slurry at -110°C through a series of metal and Pyrex traps. The purified gas is then condensed into a Pyrex sample tube before it is transferred to an isotope ratio mass spectrometer for silicon isotope ratio measurements. This system has silicon yields of greater than 90% for pure quartz, olivine, and garnet standards and has a reproducibility of ±0.1‰ (2σ) for pure quartz for both oxygen and silicon isotope measurements. Meteoritic samples were also successfully analyzed to demonstrate this system's ability to measure the isotopic ratio composition of bulk powders with precision. This unique technique allows for the fluorination of planetary material without the need for wet chemistry. Though designed to analyze small aliquots of meteoritic material (1.5 to 3 mg), this approach can also be used to investigate refractory terrestrial samples where traditional fluorination is not suitable.