Fracture pattern development has been a challenging area of research in the Earth sciences for more than 100 years. Much has been learned about the spatial and temporal complexity inherent to these ...systems, but severe challenges remain. Future advances will require new approaches. Chemical processes play a larger role in opening‐mode fracture pattern development than has hitherto been appreciated. This review examines relationships between mechanical and geochemical processes that influence the fracture patterns recorded in natural settings. For fractures formed in diagenetic settings (~50 to 200 °C), we review evidence of chemical reactions in fractures and show how a chemical perspective helps solve problems in fracture analysis. We also outline impediments to subsurface pattern measurement and interpretation, assess implications of discoveries in fracture history reconstruction for process‐based models, review models of fracture cementation and chemically assisted fracture growth, and discuss promising paths for future work. To accurately predict the mechanical and fluid flow properties of fracture systems, a processes‐based approach is needed. Progress is possible using observational, experimental, and modeling approaches that view fracture patterns and properties as the result of coupled mechanical and chemical processes. A critical area is reconstructing patterns through time. Such data sets are essential for developing and testing predictive models. Other topics that need work include models of crystal growth and dissolution rates under geological conditions, cement mechanical effects, and subcritical crack propagation. Advances in machine learning and 3‐D imaging present opportunities for a mechanistic understanding of fracture formation and development, enabling prediction of spatial and temporal complexity over geologic timescales. Geophysical research with a chemical perspective is needed to correctly identify and interpret fractures from geophysical measurements during site characterization and monitoring of subsurface engineering activities.
Plain Language Summary
Fracture patterns in rock strongly affect directions, magnitudes, and heterogeneities of both fluid flow and rock strength. Accurate and testable predictions of patterns are essential for understanding many societally important processes in the Earth and for effectively managing subsurface engineering operations. Chemical processes play a larger role in opening‐mode fracture pattern development than has hitherto been appreciated. For fractures formed at depths of ~1–10 km and temperatures of 50–200 °C, new evidence shows chemical reactions are common and more diverse than previously recognized. We describe how viewing fracture formation and evolution from a chemical perspective helps to solve problems in fracture pattern analysis. We outline the main impediments to subsurface fracture pattern measurement and interpretation, assess implications of recent discoveries in fracture history reconstruction for process‐based models of fracture and cement accumulation, review models of fracture cementation and chemically assisted fracture growth, and discuss promising paths for future work. Potential exists for basic scientific investigations to lead to progress on what has been one of the most refractory practical problems in subsurface science. Results suggest that progress in fracture interpretation and prediction can be made using observational, experimental, modeling, and theoretical approaches that view fracture patterns as the result of coupled mechanical and chemical processes.
Key Points
A chemical perspective helps solve challenges to understanding subsurface fractures: inadequate samples, ambiguous analogs, and difficulties determining which models are correct from observations
Many tools of chemical analysis, experiment, modeling, and theory have yet to be brought to bear on understanding how fracture patterns develop at geological timescales
Chemical and mechanical investigations together have great potential to solve challenging practical problems in subsurface science
The release of RNA-containing extracellular vesicles (EV) into the extracellular milieu has been demonstrated in a multitude of different in vitro cell systems and in a variety of body fluids. ...RNA-containing EV are in the limelight for their capacity to communicate genetically encoded messages to other cells, their suitability as candidate biomarkers for diseases, and their use as therapeutic agents. Although EV-RNA has attracted enormous interest from basic researchers, clinicians, and industry, we currently have limited knowledge on which mechanisms drive and regulate RNA incorporation into EV and on how RNA-encoded messages affect signalling processes in EV-targeted cells. Moreover, EV-RNA research faces various technical challenges, such as standardisation of EV isolation methods, optimisation of methodologies to isolate and characterise minute quantities of RNA found in EV, and development of approaches to demonstrate functional transfer of EV-RNA in vivo. These topics were discussed at the 2015 EV-RNA workshop of the International Society for Extracellular Vesicles. This position paper was written by the participants of the workshop not only to give an overview of the current state of knowledge in the field, but also to clarify that our incomplete knowledge - of the nature of EV(-RNA)s and of how to effectively and reliably study them - currently prohibits the implementation of gold standards in EV-RNA research. In addition, this paper creates awareness of possibilities and limitations of currently used strategies to investigate EV-RNA and calls for caution in interpretation of the obtained data.
AbstractKlebsiella michiganensis is a newly emerging human pathogen. We describe a case of bloodstream infection in an immunocompromised patient. The pathogen was repeatedly isolated from blood and ...one rectal swab, and was identified using routine standard procedures. Further investigations revealed that the K. michiganensis was multidrug resistant, carrying a plasmid harbouring a Klebsiella pneumoniae carbapenemase (KPC)-3 carbapenemase gene. This plasmid has been frequently encountered in K. pneumoniae isolates in Europe but has never been described in K. michiganensis.
Prostatic diseases in intact male dogs are common. However, studies about the computed tomographic (CT) examination of the prostate in dogs are rare. The aim of the present study was to evaluate age ...related-changes in the canine prostate with the help of the CT and to evaluate whether measuring Hounsfield Units (HUs) in different morphological conditions of the prostate is of diagnostic value. Fifty pre- and post-contrast CT scans of the prostate of dogs were evaluated and divided into three groups according to the tissue structure: Group1 dogs with homogenous prostate tissue (16/50); group 2 with prostate cysts (26/50) and group 3 with inhomogeneous prostate tissue (8/50). The prostatic dimensions were measured and the ratio between length, height and width and the sixth lumbar vertebra was calculated. Median values of prostatic attenuation measured in HUs, using regions of interests (ROIs) were determined on pre- and post- contrast scans over the whole length of the prostate. The results were compared to the dog's age. Furthermore, the CT Images were compared with the results of ultrasonography (47/50).
On pre-contrast scans HUs within ROIs placed in the prostate did not differ statistically significantly between the different morphological groups (1: 37.7; 2: 36.3; 3: 39.8 HU). HUs within on the post- contrast scans showed statistically significant differences between the groups. Group one had a mean density of 93.6 HU, group two had a mean density of 106.1 HU and group three had one of 138.2 HU. The prostatic size in the first group was smaller than in the other groups, whereas the largest prostates were found in the second group. In six cases the post-contrast CT scan showed results that differed from the ultrasound examination. Dogs had a homogenous tissue in ultrasonography while the CT scan revealed an inhomogeneous tissue structure.
The CT examination can be a beneficial diagnostic tool for examining the prostatic size and for evaluating the prostatic tissue. The different HUs reflected age-related changes and alterations in the prostate while measuring the density of the prostate. Contrast agent application enables a more specific analysis of the prostate to be carried out and for precise changes in tissue structure to be observed.
A simple and versatile method for the preparation of functional enzyme−gold nanoparticle conjugates using “click” chemistry has been developed. In a copper-catalyzed 1,2,3-triazole cycloaddition, an ...acetylene-functionalized Thermomyces lanuginosus lipase has been attached to azide-functionalized water-soluble gold nanoparticles under retention of enzymatic activity. The products have been characterized by gel electrophoresis and a fluorometric lipase activity assay. It is estimated that the equivalent of approximately seven fully active lipase molecules are attached to each nanoparticle.
This paper provides a synthesis of results that have emerged from recent modeling studies of the potential sensitivity of U.S. regional ozone (O₃) concentrations to global climate change (ca. 2050). ...This research has been carried out under the auspices of an ongoing U.S. Environmental Protection Agency (EPA) assessment effort to increase scientific understanding of the multiple complex interactions among climate, emissions, atmospheric chemistry, and air quality. The ultimate goal is to enhance the ability of air quality managers to consider global change in their decisions through improved characterization of the potential effects of global change on air quality, including O₃. The results discussed here are interim, representing the first phase of the EPA assessment. The aim in this first phase was to consider the effects of climate change alone on air quality, without accompanying changes in anthropogenic emissions of precursor pollutants. Across all of the modeling experiments carried out by the different groups, simulated global climate change causes increases of a few to several parts per billion (ppb) in summertime mean maximum daily 8-h average O₃ concentrations over substantial regions of the country. The different modeling experiments in general do not, however, simulate the same regional patterns of change. These differences seem to result largely from variations in the simulated patterns of changes in key meteorological drivers, such as temperature and surface insolation. How isoprene nitrate chemistry is represented in the different modeling systems is an additional critical factor in the simulated O₃ response to climate change.
The purpose of this study was to determine the 12 months medical resource use following admission to hospital with acute stroke and to calculate costs from a societal perspective. Data of consecutive ...patients with confirmed stroke were analysed. Acute hospital data were taken from medical records, socio‐demographic variables from patients’ interviews. A follow‐up questionnaire about resource utilization was completed by patients or proxies 12 months after acute hospital admission. Costs were calculated by multiplying medical resource units used with cost factors per unit. Mean age of a total of 383 patients was 65 years and 41% were female. The median length of the initial stay in the acute hospital was 12 days at an average cost of €4650 per patient (49% of direct costs). Rehabilitation (16%), readmission (11%), medication (9%), and nursing costs (6%) were other contributors to the direct costs which amounted to a total of €9452 ± 7599 per patient during 12 months. Indirect cost amounted to a total of €2014 ± 5312. Patients’ age, severity and type of stroke influenced the total stroke‐associated costs. The large economic burden of stroke indicates the need for assessing and improving efficient health care for affected patients.
Stroke is associated with a considerable burden of disease worldwide. Data about prevalence needs regular updating to facilitate health care planning and resource allocation. The purpose of the ...present study was to determine stroke prevalence in a large urban population in an easy and reliable way.
In a population survey a total of 75,720 households with at least 1 person >or=50 years received information about stroke symptoms by mail. In addition, the Stroke Symptom Questionnaire assessing the prevalence of stroke and of stroke symptoms was sent. Stroke prevalence was determined by a single physician-diagnosed stroke-screening question or by the combination of the latter with reported visual impairment and/or articulation problems in the past.
A total of 28,090 persons responded (37.5%). Mean (+/-SD) age was 64.4 +/- 9.7 years, 62.9 +/- 8.9 for men (43.3%), and 65.5 +/- 10.2 for women. Of all participants 2.7% reported impaired vision, 2.8% facial weakness, 2.8% articulation problems, 3.9% limb weakness, and 5% sensory disturbances. A total of 4.5% reported a physician-diagnosed stroke (women 4.3%; men 4.9%). Combining reported stroke history with reported impaired vision and/or articulation problems, the prevalence of stroke increased to 7.6% (men 8.4%; women 7.2%). Factors associated with higher prevalence were higher age, male gender, non-German nationality, lower education, positive family history of stroke, and living alone.
The combination of questions concerning a prior stroke and stroke symptoms is a useful and easy approach to assess prevalence. It results in prevalence numbers which might compensate for an underestimation of stroke numbers.
Biohybrid amphiphiles have been prepared from terminal azide functionalised polystyrene and an alkyne functionalised peptide or protein via a Cu(I) catalysed Huisgen 3 + 2 dipolar cycloaddition ...reaction.
Background and purpose: Educating the public to screen for vascular risk factors and have them treated is a major public health issue. We assessed the vascular risk factor awareness and frequency of ...treatment in a cohort of patients with cerebral ischaemia.
Methods: Data on awareness and pharmacological treatment of vascular risk factors before hospital admission of patients with confirmed ischaemic stroke/transient ischaemic attack (TIA) were analyzed. A follow‐up questionnaire assessed the frequency of treatment 1 year after discharge and assessed non‐adherence to antithrombotic medication.
Results: At time of stroke/TIA, individual awareness regarding existing hypertension, diabetes, hyperlipidemia and atrial fibrillation (AF) was 83%, 87%, 73% and 69% respectively (n = 558). Pharmacological treatment for hypertension, diabetes, hyperlipidemia and AF was being administered in 80%, 77%, 37% and 62% of patients aware of their conditions. The follow‐up was completed by 383 patients (80% recall rate): of the patients with hypertension, diabetes, hyperlipidemia and AF, 89%, 78%, 45% and 86% were receiving risk factor targeted medication. This represents a significant increase concerning AF and hyperlipidemia. Non‐adherence to recommended antithrombotics (15%) was higher in patients who had had a TIA.
Conclusions: All risk factors leave room for improvement in screening and treatment efforts. Adherence to treatment is higher for hypertension and diabetes than for hyperlipidemia. Education efforts should bear in mind less well recognized risk factors.
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