Quantifying the Permeability Enhancement from Blast-Induced Microfractures in Porphyry Rocks Using a Cumulant Lattice Boltzmann Method

The permeability of rocks is important in a range of geoscientific applications, including $$\hbox {CO}_{2}$$ CO 2 sequestration, geothermal energy extraction, and in situ mineral recovery. This work presents an investigation of the change in permeability in porphyry rock samples due to blast-induced fracturing. Two samples were analysed before and after exposure to stress waves induced by the detonation of an explosive charge. Micro-computed tomography was used to image the interior of the samples at a pixel resolution of $$10.3\,\mu m$$ 10.3 μ m . The images were segmented into void, matrix, and grain to help quantify the differences in the rock samples. Following this, they were binarised as void or solid and the cumulant lattice Boltzmann method (LBM) was applied to simulate the flow of fluid through the connected void space. A correction required with the use of inlet and outlet reservoirs in computational permeability assessment was also proposed. Interrogation of the steady-state flow field allowed the pre- and post-loading permeability to be extracted. Conclusions were then drawn as to the effectiveness of blasting for enhancing fluid accessibility via the generation of microfractures in the rock matrix within the vicinity of a detonated charge. This paper makes contributions in three fundamental areas relating to the numerical assessment of permeability and the enhancement of fluid accessibility in low-porosity rocks. Firstly, a correction factor was proposed to account for the reservoirs commonly imposed on digitised rock samples when investigating sample permeability through numerical methods. Secondly, it validates the benefits of the LBM in handling complex geometries that would be intractable with conventional computational fluid dynamics methods that require body-fitted meshing. This is done with a novel implementation of the cumulant LBM in the open-source TCLB code. Finally, the improvement in fluid accessibility in low-permeability rock samples was shown through the assessment of multiple regions within two blasted samples. It was found that the blast-induced loading can generate extended microfractures that results in multiple orders of magnitude of permeability enhancement if the target rock possesses existing weaknesses and/or mineralisation.

Screening of Bacillus mojavensis biofilms and biosurfactants using laser ablation electrospray ionization mass spectroscopy

AIMS

Biofilms are composed of micro-organisms within a matrix of chemically complex polymer compounds and from these structures many unknown competitive factors are suggested that many considered are important consequences for biological control. This research was undertaken to study further the endophyte, Bacillus mojavensis and its relationships to biofilm and two classes of lipopeptides considered relevant for biocontrol of plant pathogens.

METHODS AND RESULTS

Laser ablation electrospray ionization mass spectrometry and conventional MS/MS were used to study in situ biofilm production and the production of lipopeptides fengycin and surfactin in different strains of B. mojavensis in plate and test tube culture on two media. All strains were capable of producing biofilm in vitro along with the accumulation of surfactin and fengycin although no concentration-dependent relationship between lipopeptide accumulation and biofilm was observed.

CONCLUSION

All strains studied produce biofilms in culture with the accumulated surfactin and fengycin, demonstrating that endophytic bacteria also produced biofilms.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study demonstrates that this endophytic species produced biofilms along with two biocontrol compounds of which one, surfactin, considered by others as a quorum sensor, highlighting its ecological role as a signalling mechanism in planta.

Volatiles produced by Bacillus mojavensis RRC101 act as plant growth modulators and are strongly culture-dependent

Volatile organic compounds (VOCs) produced by Plant Growth Promoting Rhizobacteria have recently been investigated due to their role in plant growth promotion and defense. Whereas some bacterial VOCs like 3-hydroxy-2-butanone (acetoin) and 2,3-butanediol produced by strains of Bacillus subtilis and Bacillus amyloliquefaciens promote plant growth, others like hydrogen cyanide and 3-phenylpropionic acid are phytotoxic, inhibiting plant growth. Bacillus mojavensis, a close relative of B. subtilis, is an endophytic bacterium of maize that has been shown to have antagonistic activity against the mycotoxigenic phytopathogen Fusarium verticillioides and growth promotion activity on maize seedlings. To investigate the growth promotion activity of B. mojavensis, Arabidopsis thaliana seedlings were grown on 1/2x Murashige & Skoog (MS) medium in divided Petri dishes while bacteria were grown either on 1/2x MS or nutrient agar (NA) medium, so that only microbial volatiles reached the seedlings. Significant plant growth promotion in Arabidopsis seedlings was observed when 1/2x MS medium was used for bacterial growth. In contrast, phytotoxicity was observed with bacterial growth on NA medium. These results indicate that VOCs produced by B. mojavensis may act as plant growth modulators rather than just promoters. Using Solid Phase Microextraction (SPME) coupled with GC-MS, the plant growth promoting compounds acetoin and 2,3-butanediol were both identified as being produced by B. mojavensis on growth promoting 1/2x MS medium. In contrast, while no phytotoxic VOC was conclusively identified from B. mojavensis on NA medium, detection of relatively high levels of acetone/2-propanone indicates its possible contribution to Arabidopsis phytotoxicity.

Bacillus mojavensis RRC101 Lipopeptides Provoke Physiological and Metabolic Changes During Antagonism Against Fusarium verticilliodes

The mycotoxigenic pathogen Fusarium verticillioides threatens the quality and utility of maize across industrial and agricultural purposes. Chemical control is complicated by the intimate endophytic lifestyle of the pathogen with its host. Bacillus mojavensis RRC101, a maize-endophytic bacterium, has been observed to reduce F. verticillioides disease severity and fumonisin accumulation when coinoculated to maize. Genome sequencing and annotation identified a number of biocontrol-relevant pathways in RRC101. Biochemical assays confirmed the presence and activity of surfactin- and fengycin-type lipopeptides, with fengycins responsible for antifungal activity against F. verticillioides. This antagonism manifests as inhibition of filamentous growth, with microscopy revealing hyphal distortions, vacuolization, and lysis. F. verticillioides secondary metabolism also responds to antagonism, with lipopeptide challenge inducing greater fumonisin production and, in the case of fengycins, eliciting pigment accumulation at sites of inhibition. Together, these data suggest that antibiotic and toxin production are components of a complex biochemical interaction among maize endophytes, one pathogenic and one beneficial.

Effect of fertilizer formulation and bioaugmentation on biodegradation and leaching of crude oils and refined products in soils

The effects of soil characteristics and oil types as well as the efficacy of two fertilizer formulations and three bioaugmentation packages in improving the bioremediation of oil-contaminated soils were assessed as a means of ex situ treatment selection and optimization through seven laboratory microcosm studies. The influence of bioremediation on leaching of oil from the soil was also investigated. The studies demonstrated the benefits ofbiostimulation to overcome nutrient limitation, as most of the soils were nutrient depleted. The application of both liquid and pelleted slow-release N and P fertilizers increased both the hydrocarbon biodegradation rates (by a factor of 1.4 to 2.9) and the percentage of hydrocarbon mass degraded (by > 30% after 12 weeks and 80% after 37 weeks), when compared with the unamended soils. Slow-release fertilizers can be particularly useful when multiple liquid applications are not practical or cost-effective. Bioaugmentation products containing inoculum plus fertilizer also increased biodegradation by 20% to 37% compared with unamended biotic controls; however, there was no clear evidence of additional benefits due to the inocula, compared with fertilizer alone. Therefore biostimulation is seen as the most cost-effective bioremediation strategy for contaminated soils with the levels of crude oil and refined products used in this study. However, site-specific considerations remain essential for establishing the treatability of oil-contaminated soils.

Ranitidine bismuth citrate with clarithromycin alone or with metronidazole for the eradication of Helicobacter pylori

BACKGROUND

Both triple therapy with ranitidine bismuth citrate (RBC) plus two antibiotics for 7 days and dual therapy of RBC with clarithromycin for 14 days have been extensively studied; both regimens effectively eradicate Helicobacter pylori. However, few studies have assessed the efficacy of dual therapy given for 7 days.

AIM

To compare the efficacy and safety of RBC 400 mg with clarithromycin 500 mg, alone or with metronidazole 400 mg, given twice daily for 7 days for the eradication of H. pylori.

METHODS

This single centre, randomized, double-blind study involved 118 patients with dyspepsia or a history of peptic ulcer disease. H. pylori infection was detected initially by CLO test, and confirmed in 109 patients by urea breath test and/or microbiology culture. H. pylori eradication was assessed 4 and 12 weeks after the end of treatment by urea breath test. H. pylori antibiotic susceptibility was assessed pre-study in all patients, and post-treatment in patients with a positive post-treatment urea breath test. Adverse events were recorded throughout the study.

RESULTS

H. pylori was eradicated in 93% of patients who received RBC with clarithromycin and metronidazole and in 84% of patients who received RBC with clarithromycin (intention-to-treat rates). Per protocol eradication rates were 98% and 90% for triple therapy and dual therapy, respectively. The eradication of metronidazole-resistant H. pylori was achieved in 100% and 88% of patients following dual therapy and triple therapy, respectively, and acquired resistance to clarithromycin occurred in only one patient following treatment failure. Both treatments were well-tolerated; only one patient (2%) was withdrawn from each treatment group due to adverse events.

CONCLUSIONS

RBC with clarithromycin and metronidazole is a highly effective and well-tolerated triple therapy regimen for the eradication of H. pylori. RBC with clarithromycin dual therapy has a similar efficacy, and offers an alternative to triple therapy when there are concerns about treatment with metronidazole or the use of multiple antibiotics. Both regimens are effective against antibiotic-resistant strains of H. pylori.

Nurr1 enhances transcription of the human dopamine transporter gene through a novel mechanism

The importance of the nuclear receptor nurr1 for the appropriate development of mesencephalic dopamine-synthesizing neurons has been clearly demonstrated through the targeted disruption of the nurr1 gene. The persistence of nurr1 expression in adult tissue suggests a possible role for this transcription factor in the maintenance, as well as development, of the dopaminergic phenotype. To address this issue, we analyzed the effects of nurr1 on the transcriptional expression of the human dopamine transporter gene (hDAT), one of the most specific phenotypic markers for dopaminergic neurons. Nurr1 enhanced the transcriptional activity of hDAT gene constructs transiently transfected into a newly described cell line (SN4741) that expresses a dopaminergic phenotype, whereas other members of the NGFI-B subfamily of nuclear receptors had lesser or no effects. Nurr1 activation of hDAT was not dependent upon heterodimerization with the retinoid X receptor. Unexpectedly, functional analysis of a series of gene constructs revealed that a region of the hDAT 5'-flanking sequence devoid of NGFI-B response element (NBRE)-like sites mediated nurr1 activation. Additional experiments using a nurr1 mutant construct suggest that nurr1 activates hDAT transcription via a novel NBRE-independent mechanism.

How Do Logical Inference Rules Help Construct Social Mental Models?

Starting from recent approaches in mental model research, it is argued that (1) logical inference rules are used in order to construct mental cliques from learned sentiment relations, and (2) social context cues (operationalized as primes) play a crucial role in activating such rules. Transitivity and antitransitivity are taken as examples, and are shown as core constituents of such models. In a first experiment, priming was achieved by announcing the sorting of fictitious persons in either two or three cliques. Thirty-one subjects studied eight sets of sentiment relations among these persons that either did or did not satisfy their primed clique expectations. They showed longer study times and more requests for additional information in the case of inconsistent fits between prime and set. Their sorting solutions also showed clear priming effects. A second experiment (n = 30) showed that when undergoing a recognition test after seeing the relation sets, subjects tended to confuse model-consistent distractors with information they had actually seen. In a third experiment (n = 30) the results from Experiment 1 were replicated using more realistic learning materials.

Temporal Adjustments in the Evaluation of Events: The "Rosy View"

In a series of three investigations we examined people's anticipation of, actual experiences in, and subsequent recollection of meaningful life events: a trip to Europe, a Thanksgiving vacation, and a 3-week bicycle trip in California. The results of all three studies supported the hypothesis that people's expectations of personal events are more positive than their actual experience during the event itself, and their subsequent recollection of that event is more positive than the actual experience. The "rosy view" phenomenon is associated with an increase in the number of negative thoughts during the event which seem to be caused by distractions, disappointment, and a less positive view of the self. However, these effects are short-lived; within days after the event, people have much more positive evaluations of the event. We discuss alternative interpretations for our findings and implications for group and organizational settings.

Ketorolac for sickle cell vaso-occlusive crisis pain in the emergency department: lack of a narcotic-sparing effect

STUDY OBJECTIVE

To determine if a single dose of intramuscular ketorolac given on presentation to the emergency department has a narcotic-sparing effect in adult patients with sickle cell vaso-occlusive crisis pain.

DESIGN

A prospective, randomized, single-dose, double-blind study.

SETTING

ED of a university hospital and an affiliated county hospital.

TYPE OF PARTICIPANTS

Eighteen adult patients who presented to the ED with sickle cell crisis pain a total of 24 times.

INTERVENTIONS

Patients were randomized to receive either ketorolac 60 mg IM or placebo on presentation to the ED. Subjects were administered meperidine on presentation and then received a standardized dose of meperidine every 30 minutes during the four-hour observation period based on the severity of pain.

MEASUREMENTS AND MAIN RESULTS

The 12 subjects in the ketorolac group received an average of 231 +/- 92 mg meperidine, whereas the 12 subjects in the placebo group received an average meperidine dose of 250 +/- 85 mg (P = .61).

CONCLUSION

The use of intramuscular ketorolac did not lead to a clinically significant reduction in the requirement for narcotics during the four-hour ED treatment period.

Chronic myelomonocytic leukemia presenting as a keratouveitis

A case of chronic myelomonocytic leukemia is described in which the patient presented on two separate occasions with peripheral corneal infiltrates. On the first occasion the white blood cell count was high, and on the second the patient's leukemia had relapsed. Resolution of the eye signs occurred following local treatment and systemic chemotherapy.

Orcein staining of leukocytes

An Orcein staining method has been developed which stains mature and immature leukocytes in blood films and bone-marrow smears. Two different patterns of staining are obtained depending upon whether staining is or is not preceded by oxidation. In the latter case, all granulocytes and some monocytes show granular reddish-brown cytoplasmic staining. When prior oxidation is used, the staining is in the form of fine grey or black cytoplasmic granules. All lymphocytes, by both techniques, are negative. It is suggested that Orcein stains sulphated mucosubstances, possibly chondroitin sulphate, which in granulocytes is concentrated in their primary granules.

Manager behavior in a social context: the impact of impression management on attributions and disciplinary actions

Two experimental studies were run to test the effects of subordinate impression management on the appraisals and responses of a manager, following an incident of poor performance. Two common impression management tactics, accounts and apologies, were manipulated in each of the studies. Subjects in both studies were experienced nursing supervisors. On the basis of the "discounting effect" reported in the attributional literature it was hypothesized that accounts of external causes for poor performance, i.e., excuses, would lead subjects to (1) attribute less responsibility to the subordinate, (2) be less personal in their responses, and (3) be less punitive in their responses. Apologies, because of their "equity restoration" effects, were expected to influence subjects' disciplinary responses to the poor performance, without necessarily affecting their attributions of responsibility. Experiment 1. which employed written stimulus materials and a repeated-measures design, provided strong support for all hypotheses. Experiment 2. which employed a film stimulus and between-subjects design, provided strong support for the accounts hypotheses but only minimal support for the apology hypotheses. The results highlight the importance of social information cues in the appraisal of performance.

Serum ferritin concentration in patients receiving maintenance hemodialysis

Studies in 144 patients on maintenace hemodialysis have shown that serum ferritin concentration is influenced by the period the patient has been on dialysis, the presence of liver disease and to some extent the underlying diagnosis. It was observed that parenteral iron therapy could still produce an increase in hemoglobin concentration when the serum ferritin was as high as 60--55 micrograms/l. This suggests that the target serum ferritin, whatever the route of iron replacement, should be at least 55 micrograms/l. The higher levels of ferritin at which an increase in hemoglobin concentration can occur, together with the variable increment in serum ferritin after parenteral iron, indicates that the simple relationship between serum ferritin and marrow iron stores may be distrubed in some patients.

Intraoperative autotransfusion for elective aortic surgery

Intraoperative autotransfusion using the Bentley ATS 100 was used in 23 patients requiring Dacron replacement of their abdominal aorta. An average 2000 ml of blood was reinfused and a total heparinization dose was given. The mean haemoglobin fell 2.8 g/dl and on average 2 pints of banked blood were given in the postoperative period. Coagulation studies performed before and after surgery showed minimal alteration. We feel that further evaluation of this system is essential so that an alternative is established for when banked blood is not available. The system is particularly useful at the present time for such emergencies as a leaking abdominal aortic aneurysm and severe trauma to the liver.

Spontaneous platelet aggregation reversed by flurbiprofen

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Letter: Drug-induced platelet antibodies

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Chronic glomerular nephritis in a man with an IgM cold autoantibody of anti-I specificity and a cold lymphocytotoxic antibody

This communication describes a young man with chronic glomerular nephritis whose serum contained cold antibodies directed against both red cells and lymphocytes. A renal biopsy revealed unusual histological features including extensive deposits of IgM and complement. Although abnormal immune responses are not uncommon in chronic renal failure, it is suggested that there may be a causal relationship between the underlying renal lesion and the abnormal antibodies.