Instrument Modes Research Articles

Chromatography–Mass Spectrometry Analysis for the Determination of the Markers and Biomarkers of Chemical Warfare Agents

This paper considers publications devoted to the development and improvement of methods for the determination of markers and biomarkers of chemical warfare agents (CWAs) using various combinations and modifications of gas and liquid chromatography–mass spectrometry. Attention is focused on the importance of choosing an optimal analysis strategy and optimizing sample preparation procedures and operating modes of analytical instruments. Published data on the selection of characteristic markers of organophosphorus CWAs and sulfur mustard gas and methods for their determination are summarized.

Evidence of a Clear Atmosphere for WASP-62b: The Only Known Transiting Gas Giant in the JWST Continuous Viewing Zone

Abstract Exoplanets with cloud-free, haze-free atmospheres at the pressures probed by transmission spectroscopy represent a valuable opportunity for detailed atmospheric characterization and precise chemical abundance constraints. We present the first optical to infrared (0.3−5 μm) transmission spectrum of the hot Jupiter WASP-62b, measured with Hubble/STIS and Spitzer/IRAC. The spectrum is characterized by a 5.1σ detection of Na i absorption at 0.59 μm, in which the pressure-broadened wings of the Na D-lines are observed from space for the first time. A spectral feature at 0.4 μm is tentatively attributed to SiH at 2.1σ confidence. Our retrieval analyses are consistent with a cloud-free atmosphere without significant contamination from stellar heterogeneities. We simulate James Webb Space Telescope (JWST) observations, for a combination of instrument modes, to assess the atmospheric characterization potential of WASP-62b. We demonstrate that JWST can conclusively detect Na, H2O, FeH, NH3, CO, CO2, CH4, and SiH within the scope of its Early Release Science (ERS) program. As the only transiting giant planet currently known in the JWST Continuous Viewing Zone, WASP-62b could prove a benchmark giant exoplanet for detailed atmospheric characterization in the James Webb era.

Defusing COVID-19: Lessons Learned from a Century of Pandemics.

Amidst the COVID-19 global pandemic of 2020, identifying and applying lessons learned from previous influenza and coronavirus pandemics may offer important insight into its interruption. Herein, we conducted a review of the literature of the influenza pandemics of the 20th century; and of the coronavirus and influenza pandemics of the 21st century. Influenza and coronavirus pandemics are zoonoses that spread rapidly in consistent seasonal patterns during an initial wave of infection and subsequent waves of spread. For all of their differences in the state of available medical technologies, global population changes, and social and geopolitical factors surrounding each pandemic, there are remarkable similarities among them. While vaccination of high-risk groups is advocated as an instrumental mode of interrupting pandemics, non-pharmacological interventions including avoidance of mass gatherings, school closings, case isolation, contact tracing, and the implementation of infection prevention strategies in healthcare settings represent the cornerstone to halting transmission. In conjunction with lessons learned from previous pandemics, the public health response to the COVID-19 pandemic constitutes the basis for delineating best practices to confront future pandemics.

Experimental test of the rotating magnetic field neutron spin-echo technique: Spin-echo and MIEZE for large energy transfers

Here we are describing the experimental realization of the rotating magnetic field neutron spin echo (RFSE) technique that is based on spin turners using truly rotating magnetic fields. RFSE has no practical limit for short Fourier times and a “shorty” instrument mode built on this principle can be easily used at generic neutron spin echo spectrometers to increase their dynamical range beyond that provided by currently used methods.The upper limit for Fourier times is estimated. The tripling of the field integral (and hence the maximum Fourier time) by means of the bootstrap method is experimentally demonstrated. The suitability of RFSE for the use of Fresnel-type correction elements aiming to equalize the field integral for divergent neutron beams scattered by the sample is shown. The experimental realization of the MIEZE method using the RFSE technique allowing for studies of depolarizing samples and/or with depolarizing sample environments is presented.

PRACTICAL ASPECTS OF OPERATING AND ANALYTICAL RELIABILITY ASSESSMENT OF FPGA-BASED I&C SYSTEMS

Operating reliability assessment of instrumentation and control systems (I&Cs) is always one of the most important activities, especially for critical domains such as nuclear power plants (NPPs). It is an important source of I&C reliability information preferable to lab testing data because it provides information on I&C reliability under real use conditions. That is the reason that now it is a common practice for companies to have an established process of collecting operating reliability data on a large variety of used components on regular basis, maintaining a database with failure information, total operation time, typical failure modes, etc. The intensive use of complicated components like field-programmable gate arrays (FPGAs) in I&C which appear in upgrades and newly-built nuclear power plants makes the task to develop and validate advanced operating reliability assessment methods that consider specific technology features very topical. Increased integration densities make the reliability of integrated circuits the most crucial point in modern NPP I&Cs. Moreover, FPGAs differ in some significant ways from other integrated circuits: they are shipped as blanks and are very dependent on the design configured into them. Furthermore, FPGA design could be changed during planned NPP outage for different reasons. Considering all possible failure modes of FPGA-based NPP instrumentation and control systems at the design stage is a quite challenging task. Therefore, operating reliability assessment is one of the most preferable ways to perform a comprehensive analysis of FPGA-based NPP I&Cs. Based on information in the literature and own experience, operational vs analytical reliability could be pretty far apart. For that reason, analytical reliability assessment using reliability block diagrams (RBD), failure modes, effects and diagnostics analysis (FMEDA), fault tree analysis (FTA), fault insertion testing (FIT), and other techniques and their combinations are important to meet requirements for such systems. The paper summarizes our experience in operating and analytical reliability assessment of FPGA based NPP I&Cs.

Protein Glycosylation Investigated by Mass Spectrometry: An Overview.

The protein glycosylation is a post-translational modification of crucial importance for its involvement in molecular recognition, protein trafficking, regulation, and inflammation. Indeed, abnormalities in protein glycosylation are correlated with several disease states such as cancer, inflammatory diseases, and congenial disorders. The understanding of cellular mechanisms through the elucidation of glycan composition encourages researchers to find analytical solutions for their detection. Actually, the multiplicity and diversity of glycan structures bond to the proteins, the variations in polarity of the individual saccharide residues, and the poor ionization efficiencies make their detection much trickier than other kinds of biopolymers. An overview of the most prominent techniques based on mass spectrometry (MS) for protein glycosylation (glycoproteomics) studies is here presented. The tricks and pre-treatments of samples are discussed as a crucial step prodromal to the MS analysis to improve the glycan ionization efficiency. Therefore, the different instrumental MS mode is also explored for the qualitative and quantitative analysis of glycopeptides and the glycans structural composition, thus contributing to the elucidation of biological mechanisms.

Properties of sub-Neptune atmospheres: TOI-270 system

ABSTRACT We investigate the potential for the James Webb Space Telescope (JWST) to detect and characterize the atmospheres of the sub-Neptunian exoplanets in the TOI-270 system. Sub-Neptunes are considered more likely to be water worlds than gas dwarfs. We model their atmospheres using three atmospheric compositions – two examples of hydrogen-dominated atmospheres and a water-dominated atmosphere. We then simulate the infrared transmission spectra of these atmospheres for JWST instrument modes optimized for transit observation of exoplanet atmospheres: NIRISS, NIRSpec, and MIRI. We then predict the observability of each exoplanet’s atmosphere. TOI-270c and d are excellent targets for detecting atmospheres with JWST transmission spectroscopy, requiring only 1 transit observation with NIRISS, NIRSpec, and MIRI; higher signal-to-noise ratio can be obtained for a clear H-rich atmosphere. Fewer than three transits with NIRISS and NIRSpec may be enough to reveal molecular features. Water-dominated atmospheres require more transits. Water spectral features in water-dominated atmospheres may be detectable with NIRISS in two or three transits. We find that the detection of spectral features in a cloudy, H-rich atmosphere does not require integrations as long as those required for the water-dominated atmosphere, which is consistent with the differences in atmospheric mean molecular weight. TOI-270c and d could be prime targets for JWST transit observations of sub-Neptune atmospheres. These results provide useful predictions for observers who may propose to use JWST to detect and characterize the TOI-270 planet atmospheres.

Increasing of Reliability of Spacecraft Control System on Base of Robust Diagnostic Models and Division Principle in Parity Space

Different directions of creation high reliability integrate spacecraft control system are discussed on base of robust diagnostic models and division principle in parity space. Problems of synthesis spacecraft control system algorithms are examined with incomplete apriory and distorted current information, action of uncontrolled and random factors, information losses and equipment failures. The structure of onboard attitude control system is synthesized and control algorithms are chosen, which guarantee robust stability and failure stability in presence indignant factors and obstacles. An instrumental structure and operational modes of spacecraft attitude control system are described. Methods of dynamic research, computer technology and modeling particularities are indicated. Diagnostic and reconfiguration algorithms for onboard complex of connection, navigation, geodesy satellites and earth inspectoral satellite in prolonged space flight utilization are proposed. Testing procedure is contains two stage: discovering and eliminating faults. Given mathematical system model is researched by means of difference signals, which forms with arise at fault emergence. The failure character is established by deciding rules on base difference signals and measures to it eliminating are took. Questions of onboard spacecraft control system failure stable improving are discussed on base principle reconfiguration with apply to adaptive logic in testing and diagnostic algorithms. The mathematical system model is researching with implementation of analytic reserving. Difference signals are formed, which arise at fault appearance. The adaptive approach to development testing and diagnostic systems provide for realization of flexible logic of control system function to take into account factual onboard equipment state. Special attention is devote to problem influence liquid fuel reactive engine agility on spacecraft control attitude system dynamic characteristics and precision. The effectiveness of prepositional approaches and algorithms is confirmed by mathematical modeling results for several actual technical systems. Recommendations to their practical applications are given.

Detection of the phase curve and occultation of WASP-100b with TESS

ABSTRACT We report the detection of the full orbital phase curve and occultation of the hot-Jupiter WASP-100b using TESS photometry. The phase curve is isolated by suppressing low-frequency stellar and instrumental modes using both a non-parametric harmonic notch filter (phasma) and semi-sector long polynomials. This yields a phase-curve signal of (73 ± 9) ppm amplitude, preferred over a null-model by ΔBIC = 25, indicating very strong evidence for an observed effect. We recover the occultation event with a suite of five temporally localized tools, including Gaussian processes and cosine filtering. This allows us to infer an occultation depth of (100 ± 14) ppm, with an additional ±16 ppm systematic error from the differences between methods. We regress a model including atmospheric reflection, emission, ellipsoidal variations, and Doppler beaming to the combined phase-curve and occultation data. This allows us to infer that WASP-100b has a geometric albedo of $A_g = 0.16^{+0.04}_{-0.03}$ in the TESS bandpass, with a maximum dayside brightness temperature of (2710 ± 100) K and a warm nightside temperature of $(2380^{+170}_{-200})$ K. Additionally, we find evidence that WASP-100b has a high thermal redistribution efficiency, manifesting as a substantial eastward hotspot offset of $(71^{+2}_{-4})^{\circ }$. These results present the first measurement of a thermal phase shift among the phase curves observed by TESS so far, and challenge the predicted efficiency of heat transport in the atmospheres of ultra-hot-Jupiters.

Improving quality of health-related quality of life (HRQOL) reporting in phase III randomized controlled trials (RCTs) of metastatic urothelial carcinoma (mUC).

467 Background: HRQOL data are increasingly used to guide patient care and health policy. However, their utility can be compromised by inadequate quality of HRQOL reporting (QHR). We aimed to systematically evaluate QHR in phase III RCTs of mUC. Methods: A comprehensive systematic review following PRISMA guidelines identified published manuscripts of phase III RCTs of mUC in English between 1985 - 2019. Supplementary material, references and companion publications were reviewed. QHR was quantified using: 1) 2013 CONSORT-PRO extension (CPE), and 2) 2003 Minimum Standard Checklist for Evaluating HRQOL Outcomes in Cancer Clinical Trials (MSC). Both scores range from 0-11, with higher scores indicating higher QHR. QHR is “probably robust” if MSC score is ≥8 and all 3 mandatory items (baseline compliance, missing data, and psychometric properties) are reported; “limited” if MSC score is 5-7; and “very limited” if MSC score is ≤4. Results: HRQOL data was collected in 7/21 (33%) mUC phase III RCTs. All reported HRQOL data as secondary/exploratory endpoints. Generic instruments included EORTC QLQ-C30 alone (n=3) or combined with EQ-5D (n=2)/McGill pain questionnaire (n=1). Disease-specific FACT-Bl was used in 1 RCT. Both checklists showed strong correlation (Spearman coefficient 0.94, p=0.001). QHR was often limited, however has improved in recent years (Table). No RCT stated HRQOL-specific hypotheses. Only 1 reported instrument validity and mode of administration. Few provided domain specific results (n=2) and statistical methods for handling missing data (n=3). Implications for clinical practice were only discussed in 3 RCTs. Conclusions: QHR has improved over time however many critical methodological deficiencies remain in mUC phase III RCTs. The use of standard checklists are encouraged to further enhance QHR and promote high quality HRQOL research. [Table: see text]

Transmission Spectroscopy of WASP-79b from 0.6 to 5.0 μm

Abstract As part of the Panchromatic Exoplanet Treasury program, we have conducted a spectroscopic study of WASP-79b, an inflated hot Jupiter orbiting an F-type star in Eridanus with a period of 3.66 days. Building on the original WASP and TRAPPIST photometry of Smalley et al., we examine Hubble Space Telescope (HST)/Wide Field Camera 3 (WFC3) (1.125–1.650 μm), Magellan/Low Dispersion Survey Spectrograph (LDSS)-3C (0.6–1 μm) data, and Spitzer data (3.6 and 4.5 μm). Using data from all three instruments, we constrain the water abundance to be −2.20 ≤ log(H2O) ≤ −1.55. We present these results along with the results of an atmospheric retrieval analysis, which favor inclusion of FeH and H− in the atmospheric model. We also provide an updated ephemeris based on the Smalley, HST/WFC3, LDSS-3C, Spitzer, and Transiting Exoplanet Survey Satellite (TESS) transit times. With the detectable water feature and its occupation of the clear/cloudy transition region of the temperature/gravity phase space, WASP-79b is a target of interest for the approved James Webb Space Telescope (JWST) Director’s Discretionary Early Release Science (ERS) program, with ERS observations planned to be the first to execute in Cycle 1. Transiting exoplanets have been approved for 78.1 hr of data collection, and with the delay in the JWST launch, WASP-79b is now a target for the Panchromatic Transmission program. This program will observe WASP-79b for 42 hr in four different instrument modes, providing substantially more data by which to investigate this hot Jupiter.

Ultra-high spatial resolution selected area electron channeling patterns

An approach for producing ultrahigh spatial resolution selected area electron channeling patterns (UHR-SACPs) using the FEI/Thermo Elstar electron column is presented. The approach uses free lens control to directly assign lens and deflector values to rock the beam about precise points on the sample surface and generate the UHR-SACPs. Modification of the lens parameters is done using a service application that is preinstalled on the microscope or using the iFast scripting interface to run a short program to assign lens and deflector currents. Using the approach outlined here, the UHR-SACPs are collected at normal instrument scanning rates and pixel densities, resulting in rapid collection times and sharp patterns with simple push button changes in instrument mode. UHR-SACPs with spatial resolutions of 300 nm with angular ranges of 20° are demonstrated, as are patterns approaching 125 nm spatial resolution with angular ranges of 4°. Such spatial resolution/angular range combinations are significantly better than any reported previously. This approach for rapidly collecting high accuracy crystallographic information greatly enhances the ability to carry out electron channeling contrast imaging (ECCI) for a broad range of materials applications.

Ground-based optical transmission spectrum of the hot Jupiter HAT-P-1b

Context. Time-series spectrophotometric studies of exoplanets during transit using ground-based facilities are a promising approach to characterize their atmospheric compositions. Aims. We aim to investigate the transit spectrum of the hot Jupiter HAT-P-1b. We compare our results to those obtained at similar wavelengths by previous space-based observations. Methods. We observed two transits of HAT-P-1b with the Gemini Multi-Object Spectrograph (GMOS) instrument on the Gemini North telescope using two instrument modes covering the 320–800 and 520–950 nm wavelength ranges. We used time-series spectrophotometry to construct transit light curves in individual wavelength bins and measure the transit depths in each bin. We accounted for systematic effects. We addressed potential photometric variability due to magnetic spots in the planet’s host star with long-term photometric monitoring. Results. We find that the resulting transit spectrum is consistent with previous Hubble Space Telescope (HST) observations. We compare our observations to transit spectroscopy models that marginally favor a clear atmosphere. However, the observations are also consistent with a flat spectrum, indicating high-altitude clouds. We do not detect the Na resonance absorption line (589 nm), and our observations do not have sufficient precision to study the resonance line of K at 770 nm. Conclusions. We show that even a single Gemini/GMOS transit can provide constraining power on the properties of the atmosphere of HAT-P-1b to a level comparable to that of HST transit studies in the optical when the observing conditions and target and reference star combination are suitable. Our 520–950 nm observations reach a precision comparable to that of HST transit spectra in a similar wavelength range of the same hot Jupiter, HAT-P-1b. However, our GMOS transit between 320–800 nm suffers from strong systematic effects and yields larger uncertainties.

No Sign of G2's Encounter Affecting Sgr A*'s X-Ray Flaring Rate from Chandra Observations

Abstract An unusual object, G2, had its pericenter passage around Sgr A*, the 4 × 106 M ⊙ supermassive black hole in the Galactic Center, in Summer 2014. Several research teams have reported evidence that, following G2's pericenter encounter, the rate of Sgr A*'s bright X-ray flares increased significantly. Our analysis carefully treats varying flux contamination from a nearby magnetic neutron star and is free from complications induced by using data from multiple X-ray observatories with different spatial resolutions. We test the scenario of an increased bright X-ray flaring rate using a massive data set from the Chandra X-ray Observatory, the only X-ray instrument that can spatially distinguish between Sgr A* and the nearby Galactic Center magnetar throughout the full extended period encompassing G2's encounter with Sgr A*. We use X-ray data from the 3 Ms observations of the Chandra X-ray Visionary Program (XVP) in 2012, as well as an additional 1.5 Ms of observations up to 2018. We use detected flares to make distributions of flare properties. Using simulations of X-ray flares accounting for important factors such as the different Chandra instrument modes, we test the null hypothesis on Sgr A*'s bright (or any flare category) X-ray flaring rate around different potential change points. In contrast to previous studies, our results are consistent with the null hypothesis; the same model parameters produce distributions consistent with the observed ones around any plausible change point.

A review of HPLC technique covering its pharmaceutical, environmental, forensic, clinical and other applications

HPLC is an analytical technique widely used for identification, separation, detection and quantification of various drugs and its related degradants. Appropriate mobile phase, stationary phase, column, column size, temperature, wavelength and gradient selection is important for the suitable compatibility and stability of drug as well as impurities and degradants. Most of the drugs as well as other compounds can be analyzed by HPLC method because of the several advantages like rapidity, specificity, accuracy, precision and ease of automation in this method. This article has been prepared with an aim to review different aspects of HPLC, such as principle, types, mode of separation, characteristics, instrumentation, important parameters and various applications of HPLC in different fields. Keyword: HPLC, Analysis, Method development and Validation, Detection, Identification, Quantitation.

Fundamental study of ion trapping and multiplexing using drift tube-ion mobility time-of-flight mass spectrometry for non-targeted metabolomics.

This study of ion accumulation/release behavior relevant to ion mobility-mass spectrometry (IM-MS) as employed for non-targeted metabolomics involves insight from theoretical studies, and controlled reference experiments involving measurement of low and high molecular mass metabolites in varying concentrations within a complex matrix (yeast extracts). Instrumental settings influencing ion trapping (accumulation time) and release conditions in standard and multiplexed operation have been examined, and translation of these insights to liquid chromatography (LC) in combination with drift tube IM-MS measurements has been made. The focus of the application is non-targeted metabolomics using carefully selected samples to allow quantitative interpretations to be made. Experimental investigation of the IM-MS ion utilization efficiency particularly focusing on the use of the Hadamard transform multiplexing with 4-bit pseudo-random pulsing sequence for assessment of low and high molecular mass metabolites is compared with theoretical modeling of gas-phase behavior of small and large molecules in the IM trapping funnel. Increasing the trapping time for small metabolites with standard IM-MS operation is demonstrated to have a deleterious effect on maintaining a quantitative representation of the metabolite abundance. The application of these insights to real-world non-targeted metabolomics assessment of intracellular extracts from biotechnologically relevant production processes is presented, and the results were compared to LC×IM-MS measurements of the same samples. Spiking of a uniformly 13C-labeled yeast extract (as a standard matrix) with varying amounts of natural metabolites is used to assess the linearity and sensitivity according to the instrument mode of operation (i.e., LC-MS, LC×IM-MS, and LC×[multiplexed]IM-MS). When comparing metabolite quantification using standard and multiplexed operation, sensitivity gain factors of 2-8 were obtained for metabolites with m/z below 250. Taken together, the simulation and experimental results of this study provide insight for optimizing measurement conditions for metabolomics and highlight the need for implementation of multiplexing strategies using short trapping times as relative quantification (e.g., in the context with non-targeted differential analysis) with sufficient sensitivity and working range is a requirement in this field of application.

Method development for simultaneous analyses of polycyclic aromatic hydrocarbons and their nitro-, oxy-, hydroxy- derivatives in sediments

It is important to establish an available analytical method for polycyclic aromatic hydrocarbons (PAHs), nitrated PAHs (nitro-PAHs), oxygenated forms of PAHs (oxy-PAHs), and hydroxy-PAHs (OH-PAHs) in sediment samples due to the fact that they co-exist in various environmental mediates, particularly in sediment. In this study, an analytical method has been developed and validated for the quantification of PAHs, nitro-PAHs, oxy-PAHs, and OH-PAHs in sediment samples. The sediment samples were extracted by accelerated solvent extraction and cleaned up with SPE alumina-n combining with aminopropyl cartridges. The extracts were further fractionated by using different solvents. The fractionated extracts were analyzed via gas chromatography of single and triple quadrupole mass spectrometry in the electron ionization and negative ion chemical ionization with selective ion monitoring and selective reaction monitoring mode and liquid chromatography-triple quadrupole mass spectrometry. Each group of analytes was determined by different instrument modes such as GC-EI-SIM for PAHs, GC-NICI-SRM for nitro-PAHs, GC-EI-SRM for the oxy-PAHs and LC-ESI-MS/MS for OH-PAHs. A total of 44 analytes (16 PAHs, 14 nitro-PAHs, 9 oxy-PAHs, and 5 OH-PAHs) and 6 deuterated surrogates were performed. Most of recovery percentage varied from 52.8% up to 114.1% for the targeted analytes verified at three concentration levels (100 ng/g, 400 ng/g and 1000 ng/g for PAHs and 10 ng/g, 50 ng/g and 400 ng/g for their derivatives). The repeatability determined by the relative standard deviation percentage of triplicate trials was less than 10% for most analytes. The limit of detection ranged from 0.01 to 0.02 ng/g for PAHs, 0.002–0.067 ng/g for nitro-PAHs, 0.01–0.1 ng/g for oxy-PAHs, and 0.003–0.006 ng/g for OH-PAHs. Most of the compounds were detectable in the sediments collected from a local River, which illustrates the developed method could be a practical and suitable technique for detection of PAHs and their derivatives in real sediment samples.

Issues in Existing Agricultural Credit and Scope of Bay‘ al-Salam as an Alternative

This study focuses on issues in agricultural finance in Pakistan and suggests the use of bay‘ al-Salam, the forward contract as allowed in Islamic law of contracts. Despite vital importance, the agriculture sector in Pakistan hasn’t been able to make the case to gain attention on the Government’s priority list. A number of negatively impacting elements can be pointed out, but the standalone interest based system of agricultural credit can be termed as the most harmful for farmers, agriculture sector and the national economy. Major problems include insufficient institutional credit, exorbitant rate of interest, non-availability of collateral and the cumbersome procedures. This situation creates a credit gap which is filled by the non-institutional sources like middlemen, shopkeepers and money lenders who too exploit the poor farmers. However, they still borrow from private sources as the access is easier. The concerns are growing about the existing interest based credit system and voices are also raised for an alternative system that is easy to access as also compliant with the Shar¯ı‘ah principles. Salam financing for the purchase of crops initiated by Sudanese banks couldn’t create desired impact fully. Similarly, Salam financing offered by First Islamic Bank of Indonesia faced serious Shar¯ı‘ah compliance issues. However, a private body namely Wasil Foundation’s bay‘ al-Salam initiative in Pakistan seems comparatively a successful story. A relatively better response and wider acceptance by the stakeholders to Salam financing offered by Wasil indicates that banks (both conventional and Islamic) cannot apply Salam efficiently due to non-availability of required infrastructure. Although Salam financing is highly instrumental mode of finance for agriculture, but could fail if managed through the Islamic banks in obtaining the desired outcome. This study, based on the literature and expert opinion collected through a survey, proposes a separate body to handle Salam financing to agriculture in Pakistan.

Plasma Transport in Saturn's Low‐Latitude Ionosphere: Cassini Data

AbstractIn 2017 the Cassini Orbiter made the first in situ measurements of the upper atmosphere and ionosphere of Saturn. The Ion and Neutral Mass Spectrometer in its ion mode measured densities of light ion species (H+, H2+, H3+, and He+), and the Radio and Plasma Wave Science instrument measured electron densities. During proximal orbit 287 (denoted P287), Cassini reached down to an altitude of about 3,000 km above the 1 bar atmospheric pressure level. The topside ionosphere plasma densities measured for P287 were consistent with ionospheric measurements during other proximal orbits. Spacecraft potentials were measured by the Radio and Plasma Wave Science Langmuir probe and are typically about negative 0.3 V. Also, for this one orbit, Ion and Neutral Mass Spectrometer was operated in an instrument mode allowing the energies of incident H+ ions to be measured. H+ is the major ion species in the topside ionosphere. Ion flow speeds relative to Saturn's atmosphere were determined. In the southern hemisphere, including near closest approach, the measured ion speeds were close to zero relative to Saturn's corotating atmosphere, but for northern latitudes, southward ion flow of about 3 km/s was observed. One possible interpretation is that the ring shadowing of the southern hemisphere sets up an interhemispheric plasma pressure gradient driving this flow.

A practical method for measuring high precision calcium isotope ratios without chemical purification for calcium carbonate samples by multiple collector inductively coupled plasma mass spectrometry

A procedure for the measurement of high precision Ca isotope ratios for calcium carbonate samples by multiple collector inductively coupled plasma mass spectrometry (MC-ICP-MS) is reported. Under instrumental low mass resolution mode, 42Ca, 43Ca and 44Ca were measured directly without column chemistry and the measurement uncertainty was 0.08‰ (2sd, n = 32). The background interference on mass 42 u was investigated and minimized to an acceptable level by tuning the sweep gas and ICP torch position. In order to ensure the reliability of the method and quantify the tolerance of samples with incorporated Sr, the effect of Sr as an interference was evaluated for different concentrations, results showing no statistical difference with Sr/Ca <0.1, implying that most natural carbonate materials are accessible by this method. To validate the accuracy of this method, several stalagmite samples were analyzed in a comparative study in the Isotope Geochemistry Laboratory, Department of Earth Sciences, Oxford University. Results from both laboratories are in good statistical agreement which supports the use of this method as a simple, practical approach for Ca isotope measurement of calcium carbonate samples.