Dissolution Kinetics of Iron Carbonate, Illite and Labradorite – CO2-Saline Fluid-mineral Experiments within the GaMin’11 Inter-laboratory Comparison Exercise

AbstractExperiments to investigate individual CO2-brine-mineral interactions were designed to provide dissolution kinetics for rock-forming minerals. Separates of an iron carbonate, a clay mineral and a feldspar mineral were stored in flexible Titanium Grade-2 cells together with 2M NaCl brine and pure CO2 at 80°C and 20 (30) MPa for one (iron carbonate), two (clay) and three (feldspar) weeks, respectively. The carbonate separate consists of 96.3±3.2 wt% iron carbonate and 3.7±0.8 wt% quartz with the iron carbonate phase being composed of 72.3±1.4 wt% siderite and 27.7±1.2 wt% ankerite. During the experiments, siderite abundance increased to 83.3±1.5 wt%, while that of ankerite decreased to 16.7±1.4 wt%. The average empirical formula of untreated and treated siderite is Fe0.8Mg0.1Mn0.1CO3, that of untreated ankerite changed slightly from (Ca1.0Mg0.2Mn0.1Fe0.7)(CO3)2 to (Ca0.9Mg0.3Mn0.1Fe0.7)(CO3)2 during CO2 exposure. Fluid data obtained during these experiments show similar behavior for Ca2+ and Mg2+, as well as Fe2+ and Mn2+, respectively. The clay separate initially consists of 84.2±6.9 wt% illite, 11.9±0.4 wt% orthoclase and 3.9±0.2 wt% quartz with untreated illite actually being an illite-smectite mixed-layer mineral composed of 87.2±1.5 wt% illite and 12.8±1.5 wt% Ca-smectite. During the experiments using the clay separate it was found that the composition changed to 88.3±7.8 wt% illite, 9.2±0.5 wt% orthoclase, and 2.5±0.2 wt% quartz, with CO2-treated illite now consisting of 89.0±1.7 wt% illite and 10.5±1.6 wt% Ca-smectite.Fluid data show, besides others, increase Ca2+ concentrations over time. Analyses of the feldspar separate reveal pure labradorite with a stoichiometric composition of Na0.5-0.6Ca0.4-0.5Al1.3-1.6Si2.4-2.6O8. During labradorite exposure experiments cation brine concentrations (e.g. Ca2+, Ba2+ and Al3+) increased. Based on the acquired geochemical data sets, the experiments using individual mineral separates indicate (i) dissolution of ankerite and stable siderite, (ii) preferred dissolution of the Ca-smectite component out of the illite-smectite mixed-layer mineral, and (iii) dissolution of labradorite

Mineral Solubilities in CO2-Saturated NaCl Brine Systems

AbstractExperiments on CO2-brine-mineral interactions were designed to provide kinetic data for individual rock-forming minerals. Samples of an illite-smectite mixed layer mineral and a labradorite separate were stored in flexible Ti-cells together with 2M NaCl brine and pure CO2 at 80°C and 20MPa for two and three weeks, respectively. The empirical formulae K0.5-0.7(Mg0.1-0.2Al1.8-1.9)(Al0.4-0.6Si3.4-3.6)O10(OH)2 and Na0.5-0.6Ca0.4-0.5Al1.3-1.6Si2.4-2.6O8 were calculated for illite and labradorite. X-ray diffraction data with Rietveld refinements reveal a pure labradorite separate. The illite separate is composed of 73.5±1.3 wt% illite, 10.8±1.3 wt% Ca-smectite, 11.9±0.4 wt% orthoclase, and 3.9±0.2 wt% quartz. Based on the acquired geochemical data, the experiments on monomineralic separates indicate (i) preferred dissolution of the Ca-smectite component out of the illite-smectite mixed layer mineral, and (ii) dissolution of labradorite

Influence of tectonic perturbations on the migration of long-lived radionuclides from an underground repository of radioactive waste

We studied the influence of tectonic perturbations on the transport of potentially mobilized radionuclides in groundwater from a deep-mined repository of solid high-level radioactive waste. The study was carried out by the method of mathematical modeling. Key parameters of the model correspond to the site of a potential federal repository in Russia. The groundwater flow domain is delimited on one side by a water divide (i.e., boundary of the catchment basin) and on the other side by the river bank. 2D simulations of groundwater flow and radionuclide migration are carried out along a vertical cross-section normal to the water divide. The groundwater flows through the rock massif, which encloses the repository, and discharges into the adjacent river. It is supposed that tectonic activity may form a fault which is parallel to the river bank. We analyzed how repository safety depends on the time of the fault emergence and on the distance between the repository and the fault. The results of our simulations suggest that: (1) emergence of a fault due to tectonic perturbations is not inevitably associated with a substantial growth of radionuclides released from the repository to the environment; (2) influence of the fault on the repository safety depends on the distance between the fault and the repository as well as on the time interval between the repository development and the fault emergence; (3) the influence of the fault on the repository safety can depend substantially on local elevations of the relief at the repository site

Measurements of H2 Solubility in Saline Solutions under Reservoir Conditions: Preliminary Results from Project H2STORE

AbstractA high-pressure/high-temperature reactor has been used to lead PVT and H2-solubility experiments in saline solutions covering conditions for which no data are available in literature: salinity up to halite concentration, pressure up to 200bar and temperature up to 373K. The hereby presented preliminary results show significant deviations from theoretical models. Further analysis and more measurements are needed to assess precision and reproducibility of these measurements; however they pinpoint the importance of experimental work to reliably constrain predictive models

Consistencies and rates of convergence of jump-penalized least squares estimators

We study the asymptotics for jump-penalized least squares regression aiming at approximating a regression function by piecewise constant functions. Besides conventional consistency and convergence rates of the estimates in $L^2([0,1))$ our results cover other metrics like Skorokhod metric on the space of c\`{a}dl\`{a}g functions and uniform metrics on $C([0,1])$. We will show that these estimators are in an adaptive sense rate optimal over certain classes of "approximation spaces." Special cases are the class of functions of bounded variation (piecewise) H\"{o}lder continuous functions of order $0<\alpha\le1$ and the class of step functions with a finite but arbitrary number of jumps. In the latter setting, we will also deduce the rates known from change-point analysis for detecting the jumps. Finally, the issue of fully automatic selection of the smoothing parameter is addressed.Comment: Published in at http://dx.doi.org/10.1214/07-AOS558 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

Does Injected CO2 Affect (Chemical) Reservoir System Integrity? - A Comprehensive Experimental Approach

AbstractIn order to investigate and characterize single fluid-mineral interactions we successfully implemented a new hydrothermal laboratory. CO2-exposure experiments using separates of rock-forming minerals were performed on a hydrothermal rocking autoclave. The system is equipped with flexible Titanium cells allowing for isobaric sampling. Experiments were run for one week at 80°C and 20 MPa/30 MPa. Rietveld refined XRD data reveal that the initial siderite separate is composed of 69.6±1.3 wt% siderite, 26.7±1.2 wt% ankerite and 3.8±0.8 wt% quartz, respectively. 0ver time, siderite abundances increase and ankerite abundances correspondingly decrease, while quartz abundances are constant within error. Fluid data show rapid increases for Ca2+, Mg2+, Mn2+ and Fe2+. After these rapid increases, Ca2+ and Mg2+ reveal slight decreases that are followed by subsequent rises to maximum concentrations at the end of the experiments, while Mn2+ and Fe2+ decrease continuously after the initial maxima. SEM micrographs of CO2-exposed samples indicate dissolution of ankerite, while siderite and quartz are mainly unaffected. The experiments on the siderite separate clearly show that ankerite is dissolved and siderite is stable. We conclude that siderite is a potential CO2 trapping phase in iron-bearing reservoirs

Association of age with the timing of acute spine surgery–effects on neurological outcome after traumatic spinal cord injury

Purpose: To investigate the association of age with delay in spine surgery and the effects on neurological outcome after traumatic spinal cord injury (SCI). Methods: Ambispective cohort study (2011-2017) in n = 213 patients consecutively enrolled in a Level I trauma center with SCI care in a metropolitan region in Germany. Age-related differences in the injury to surgery interval and conditions associated with its delay (> 12 h after SCI) were explored using age categories or continuous variables and natural cubic splines. Effects of delayed surgery or age with outcome were analyzed using multiple logistic regression. Results: The median age of the study population was 58.8 years (42.0-74.6 IQR). Older age (>= 75y) was associated with a prolonged injury to surgery interval of 22.8 h (7.2-121.3) compared to 6.6 h (4.4-47.9) in younger patients ( 60 h = 40y 5-20% probability). Conclusion: Older patient age complexifies surgical SCI care and research. Tackling secondary referral to Level I trauma centers and delayed spine surgery imposes as tangible opportunity to improve the outcome of older SCI patients

a clinical study protocol

Introduction The approved analgesic and anti-inflammatory drugs ibuprofen and indometacin block the small GTPase RhoA, a key enzyme that impedes axonal sprouting after axonal damage. Inhibition of the Rho pathway in a central nervous system-effective manner requires higher dosages compared with orthodox cyclooxygenase-blocking effects. Preclinical studies on spinal cord injury (SCI) imply improved motor recovery after ibuprofen/indometacin-mediated Rho inhibition. This has been reassessed by a meta-analysis of the underlying experimental evidence, which indicates an overall effect size of 20.2% regarding motor outcome achieved after ibuprofen/indometacin treatment compared with vehicle controls. In addition, ibuprofen/indometacin may also limit sickness behaviour, non-neurogenic systemic inflammatory response syndrome (SIRS), neuropathic pain and heterotopic ossifications after SCI. Consequently, ‘small molecule’-mediated Rho inhibition after acute SCI warrants clinical investigation. Methods and analysis Protocol of an investigator-initiated clinical open-label pilot trial on high-dose ibuprofen treatment after acute traumatic, motor-complete SCI. A sample of n=12 patients will be enrolled in two cohorts treated with 2400 mg/day ibuprofen for 4 or 12 weeks, respectively. The primary safety end point is an occurrence of serious adverse events, primarily gastroduodenal bleedings. Secondary end points are pharmacokinetics, feasibility and preliminary effects on neurological recovery, neuropathic pain and heterotopic ossifications. The primary safety analysis is based on the incidence of severe gastrointestinal bleedings. Additional analyses will be mainly descriptive and casuistic. Ethics and dissemination The clinical trial protocol was approved by the responsible German state Ethics Board, and the Federal Institute for Drugs and Medical Devices. The study complies with the Declaration of Helsinki, the principles of Good Clinical Practice and all further applicable regulations. This safety and pharmacokinetics trial informs the planning of a subsequent randomised controlled trial. Regardless of the result of the primary and secondary outcome assessments, the clinical trial will be reported as a publication in a peer-reviewed journal. Trial registration number NCT02096913; Pre-results

protocol of a prospective, longitudinal study

Background Natural killer (NK) cells comprise the main components of lymphocyte-mediated nonspecific immunity. Through their effector function they play a crucial role combating bacterial and viral challenges. They are also thought to be key contributors to the systemic spinal cord injury-induced immune-deficiency syndrome (SCI-IDS). SCI-IDS increases susceptibility to infection and extends to the post-acute and chronic phases after SCI. Methods and design The prospective study of NK cell function after traumatic SCI was carried out in two centers in Berlin, Germany. SCI patients and control patients with neurologically silent vertebral fracture also undergoing surgical stabilization were enrolled. Furthermore healthy controls were included to provide reference data. The NK cell function was assessed at 7 (5–9) days, 14 days (11–28) days, and 10 (8–12) weeks post-trauma. Clinical documentation included the American Spinal Injury Association (ASIA) impairment scale (AIS), neurological level of injury, infection status, concomitant injury, and medications. The primary endpoint of the study is CD107a expression by NK cells (cytotoxicity marker) 8–12 weeks following SCI. Secondary endpoints are the NK cell’s TNF-α and IFN-γ production by the NK cells 8–12 weeks following SCI. Discussion The protocol of this study was developed to investigate the hypotheses whether i) SCI impairs NK cell function throughout the post-acute and sub-acute phases after SCI and ii) the degree of impairment relates to lesion height and severity. A deeper understanding of the SCI-IDS is crucial to enable strategies for prevention of infections, which are associated with poor neurological outcome and elevated mortality. Trial registration DRKS00009855

The spinal cord injury-induced immune deficiency syndrome: results of the SCIentinel study

Infections are prevalent after spinal cord injury (SCI), constitute the main cause of death and are a rehabilitation confounder associated with impaired recovery. We hypothesize that SCI causes an acquired lesion-dependent (neurogenic) immune suppression as an underlying mechanism to facilitate infections. The international prospective multicentre cohort study (SCIentinel; protocol registration DRKS00000122; n = 111 patients) was designed to distinguish neurogenic from general trauma-related effects on the immune system. Therefore, SCI patient groups differing by neurological level, i.e. high SCI [thoracic (Th)4 or higher]; low SCI (Th5 or lower) and severity (complete SCI; incomplete SCI), were compared with a reference group of vertebral fracture (VF) patients without SCI. The primary outcome was quantitative monocytic Human Leukocyte Antigen-DR expression (mHLA-DR, synonym MHC II), a validated marker for immune suppression in critically ill patients associated with infection susceptibility. mHLA-DR was assessed from Day 1 to 10 weeks after injury by applying standardized flow cytometry procedures. Secondary outcomes were leucocyte subpopulation counts, serum immunoglobulin levels and clinically defined infections. Linear mixed models with multiple imputation were applied to evaluate group differences of logarithmic-transformed parameters. Mean quantitative mHLA-DR [ln (antibodies/cell)] levels at the primary end point 84 h after injury indicated an immune suppressive state below the normative values of 9.62 in all groups, which further differed in its dimension by neurological level: high SCI [8.95 (98.3% confidence interval, CI: 8.63; 9.26), n = 41], low SCI [9.05 (98.3% CI: 8.73; 9.36), n = 29], and VF without SCI [9.25 (98.3% CI: 8.97; 9.53), n = 41, P = 0.003]. Post hoc analysis accounting for SCI severity revealed the strongest mHLA-DR decrease [8.79 (95% CI: 8.50; 9.08)] in the complete, high SCI group, further demonstrating delayed mHLA-DR recovery [9.08 (95% CI: 8.82; 9.38)] and showing a difference from the VF controls of -0.43 (95% CI: -0.66; -0.20) at 14 days. Complete, high SCI patients also revealed constantly lower serum immunoglobulin G [-0.27 (95% CI: -0.45; -0.10)] and immunoglobulin A [-0.25 (95% CI: -0.49; -0.01)] levels [ln (g/l × 1000)] up to 10 weeks after injury. Low mHLA-DR levels in the range of borderline immunoparalysis (below 9.21) were positively associated with the occurrence and earlier onset of infections, which is consistent with results from studies on stroke or major surgery. Spinal cord injured patients can acquire a secondary, neurogenic immune deficiency syndrome characterized by reduced mHLA-DR expression and relative hypogammaglobulinaemia (combined cellular and humoral immune deficiency). mHLA-DR expression provides a basis to stratify infection-risk in patients with SCI