Double Resistance Research Articles

The Quantitative Description of Tight Sand Reservoir Fracture in Sulige Gas Field

The Sulige gas field is a typical tight sand reservoir, Ordos Basin, the fracture development degree directly affects the development of the natural gas, especially affects the volume fracturing effect of horizontal well and the deliverability of the natural gas, the appropriate method to describe the fracture is very important. At present, outcrop, core and FIM are general methods to describe the fracture development degree, but they have inherent shortages. In the Sulige gas field, a few of cores and poor representativeness can not illustrate the fracture distribution in well bore, and imaging logging data are especially absent. Su53 gas field was used as an example in the Sulige gas field, during the research of the fracture, based on fractal theory, through using the amplitude difference data between deep investigate double lateral resistivity (Rd) and shallow investigate double lateral resistivity (Rs), and other conventional logging data, in combination with the response characteristics of fracture in the logging curve, reservoir fracture was quantitatively identified by the analysis method of R / S , the relationship between fractal dimension value and fracture density was quantitatively analyzed , the vertical heterogeneity of fracture distribution was analyzed, and the relationship between fractal dimension value of fracture and initial deliverability of gas well was researched. The results which were tested by the data of drilling cores and productions available, indicate that the method of R / S is feasible to quantitatively describe the fracture development degree; the relationship between fractal dimension value and fracture density is positively relative, fractal dimension value is bigger, the fracture is more developed; there is a good corresponding relationship between fractal dimension value and deliverability of gas well, fractal dimension value decreases with a decrease of deliverability. Key words: Fractal; R / S analysis; Logging curve; Tight sand reservoir fracture; Fracture description

Differing Responses in Growth and Spontaneous Mutation to Antibiotic Resistance in Bacillus subtilis and Staphylococcus epidermidis Cells Exposed to Simulated Microgravity

ABSTRACT Bacteria of the genera Bacillus and Staphylococcus are frequent inhabitants of the International Space Station (ISS) and represent possible opportunistic pathogens. The effect of simulated microgravity on growth and the frequency of mutation to antibiotic resistance in the model surrogate organisms Bacillus subtilis (B. subtilis) and Staphylococcus epidermidis (S. epidermidis) were investigated. The test organisms were cultivated for six days in Rotating Wall Vessel (RWV) clinostats either in the vertical (simulated microgravity) or horizontal (1 g control) orientation. Parameters measured were: optical densities (ODs); viable counts; frequencies of resistance to rifampicin (RFM); and frequencies of double resistance to RFM and trimethoprim (TMP). The results indicated that the response to simulated microgravity differed in the two microorganisms. Both B. subtilis and S. epidermidis grew to higher ODs and cell numbers in simulated microgravity. However, the frequencies of mutation, both to RFM resistance and double resistance to RFM and TMP, were observed to increase significantly in simulated microgravity-grown B. subtilis but not in S. epidermidis.

The Vat locus encodes for a CC-NBS-LRR protein that confers resistance to Aphis gossypii infestation and A.gossypii-mediated virus resistance.

Aphis gossypii is a polyphagous sucking aphid and a vector for many viruses. In Cucumis melo, a dominant locus, Vat, confers a high level of resistance to Aphis gossypii infestation and to viruses transmitted by this vector. To investigate the mechanism underlying this double resistance, we first genetically dissected the Vat locus. We delimited the double resistance to a single gene that encodes for a coiled-coil-nucleotide-binding-site-leucine-rich repeat (CC-NBS-LRR) protein type. To validate the genetic data, transgenic lines expressing the Vat gene were generated and assessed for the double resistance. In this analysis, Vat-transgenic plants were resistant to A.gossypii infestation as well as A.gossypii-mediated virus transmission. When the plants were infected mechanically, virus infection occurred on both transgenic and non-transgenic control plants. These results confirmed that the cloned CC-NBS-LRR gene mediates both resistance to aphid infestation and virus infection using A.gossypii as a vector. This resistance also invokes a separate recognition and response phases in which the recognition phase involves the interaction of an elicitor molecule from the aphid and Vat from the plant. The response phase is not specific and blocks both aphid infestation and virus infection. Sequence analysis of Vat alleles suggests a major role of an unusual conserved LRR repeat in the recognition of A.gossypii.

Fitness of Erysiphe necator with G143A-Based Resistance to Quinone Outside Inhibitors.

Management of grape powdery mildew (Erysiphe necator) using quinone outside inhibitors (QoIs) has eroded in an increasing number of regions due to resistance development. To determine persistence of resistance when QoIs are withdrawn, competition assays were conducted on unsprayed grape plants (Vitis vinifera 'Chardonnay') by cycling mixtures of resistant and sensitive isolates characterized as genetically diverse based on microsatellite analyses. Under laboratory conditions, %G143A, quantified by quantitative polymerase chain reaction (qPCR), increased significantly, indicating competitiveness of the resistant fraction. To confirm competitiveness in the field, trials using potted plants were conducted. Percent G143A tended to decrease in one growing season, probably due to spore migration and mixing of populations with natural background inoculum. In a second season, QoI resistance persisted at high frequency for 4 weeks. Resistant populations were also found to persist in one vineyard without QoI application for four consecutive years. The frequency was still about 25% in the fourth year, with higher frequency (36%) in a hotspot section. QoI-resistant populations with >5% G143A also harbored Y136F in the cyp51 gene that confers some resistance to sterol demethylation inhibitors, another fungicide class for powdery mildew control. Double resistance could have been partly responsible for persistence of QoI resistance at this location.

English

The pollution of marine environment with heavy metals, antibiotics, dyes and surfactants may possess a serious threat to human life and the other organisms because of their toxicity and ability to persist for long time. The metals and antibiotics resistance of 48 heterotrophic bacterial isolates from hospital waste water and polluted sea water were studied. The minimum inhibitory concentrations (MICs) of heavy metals were different for each isolate. All isolates showed high resistance to nickel, chromium, barium and copper. On the other hand, mercury was the highest toxic metal against all the isolates. The frequencies of resistance for all isolates to each metal ion tested were as follows: Ni, 88%; Ba, 88%; Cr, 75%; Cu, 38% and Hg, 13% for hospital waste water isolates, and Ni, 88%; Ba, 75%; Cr, 50%; Cu, 50%  and Hg, 0% for seawater bacteria. The response of the isolates to five antibiotics was tested; it ranged from complete resistance to total sensitivity. The hospital waste water isolates showed resistance for 4 of 5 antibiotics with percentages that ranged from 13 to 100%. On the other hand, 88% of seawater isolates resisted only one antibiotic. Multiple-metal resistance was exhibited by 100% of heterotrophic bacteria, while penta-metal-resistant bacteria was observed only in hospital waste water isolates. Multiple-antibiotic resistance was exhibited by 63% of the hospital waste water bacteria. The highest incidence of metal-antibiotic double resistance was observed in hospital waste water isolates compared with sea water isolates. Moreover, all isolates exhibited multiple resistances for different dyes as crystal violet, iodine and sufranine and other chemicals such as sodium lurayl sulfate. The bacterial isolates from hospital waste water showed higher resistance to dyes and surfactant than those isolated from polluted seawater. The composition of bacterial communities which were resistant to different chemicals ranged from 0.02 to 0.33% for the bacterial pathogens and from 1.95 to 15.0% for the fecal bacteria in the hospital waste water whereas, in seawater samples, the percentages of bacterial pathogens ranged from 0.04 to 0.12% and the percentages fecal bacteria ranged from 0.95 to 29.10%. This finding suggests that the discharge of hospital waste water without preliminary treatment is an important source for the spread of new phenotype bacteria with multiple-resistance in natural habitats which can pose a public health risk. Key words: Metal resistance, antibiotic resistance, heterotrophic bacteria, hospital waste water, polluted sea water.

Prevalence of multiple drug-resistant Helicobacter pylori strains among patients with different gastric disorders in Iran.

Emergence of multidrug-resistant (MDR) strains of Helicobacter pylori is a global health concern. This study was aimed to determine the frequency of MDR H. pylori strains in Iran. H. pylori isolates were obtained from cultured gastric biopsy samples on selective culture media after their characterization by PCR and conventional biochemical methods. The minimal inhibitory concentrations of rifampicin, ciprofloxacin, levofloxacin, ampicillin, clarithromycin, erythromycin, metronidazole, and tetracycline were determined for 111 strains that were isolated from 197 dyspeptic patients by the agar dilution method. The primary resistance rates were 61.3% (68/111) for metronidazole, 15.3% (17/111) for ampicillin, and 14.4% (16/111) for rifampicin. Resistance rates for other antimicrobials were as follows: macrolides (erythromycin or clarithromycin) 32.4% (36/111) and quinolones (levofloxacin or ciprofloxacin) 30.6% (34/111). Among the resistant strains, the rates of double and multiple drug resistance phenotypes were 22.6% (19/84) and 34.5% (29/84), respectively. The quadruple drug resistance phenotype encompasses 37.9% of the MDR strains, of which 90% of them was resistant to metronidazole. In conclusion, these results showed a high frequency of MDR phenotypes among the studied H. pylori strains in Iran. The eradication of the H. pylori strains presenting high resistance rates to macrolides, fluoroquinolones, or metronidazole could be achieved by approved tetracycline- or amoxicillin-containing regimens as alternative regimens to standard triple therapy.

Sensitivity of Cercospora beticola isolates from Serbia to carbendazim and flutriafol

Cercospora beticola, causal agent of Cercospora leaf spot (CLS) of sugar beet, is primarily controlled by fungicides. Benzimidazole and demethylation inhibiting fungicides, including carbendazim and flutriafol, have been widely used in Serbia. Since these fungicide groups have a site-specific mode of action, there is a high risk for developing resistance in target organisms, which is the most important limiting factor in Cercospora leaf spot chemical control. A rapid identification of flutriafol and carbendazim resistance can help researchers in examining the potential of different fungicide resistance management practices, as well as in selection of fungicides for use in the areas where resistance has occurred. One hundred single-conidia isolates were collected from 70 representative locations of the sugar beet production region in Serbia. Evaluation of the isolates' sensitivity was based on the reduction of mycelial growth on medium amended with 1.25 μg mL−1 flutriafol and 5 μg mL−1 carbendazim. Resistance to flutriafol and carbendazim was detected in 16% and 96% of the tested isolates, respectively. All isolates resistant to flutriafol were resistant to carbendazim as well, which is the first report of a double resistance to fungicides in C. beticola. Detection of the isolates resistant to flutriafol and carbendazim using Cleaved Amplified Polymorphic Sequence (CAPS) markers confirmed the results of the in vitro tests. The efficacy of carbendazim, flutriafol, azoxystrobin, and tetraconazole at commercially recommended doses was evaluated in field trials where sugar beet plants in plots were inoculated with a mixture of isolates either sensitive and/or resistant to flutriafol and carbendazim. Carbendazim and flutriafol efficacy was very low in plots inoculated with isolates resistant to these fungicides. Presented results will contribute to development of a pathogen population sensitivity monitoring strategy that could be used for an effective CLS management in the region.

Prospective multi-region study on primary antibiotic resistance of Helicobacter pylori strains isolated from Chinese patients

BackgroundLarge-scale multi-region studies are urgently needed to provide comprehensive and up-to-date information on the antibiotic resistance of Helicobacter pylori that is critical for selecting the most optimal eradication regimens. AimsTo determine the resistance patterns of Helicobacter pylori strains isolated from dyspeptic patients. MethodsThis is a prospective, multicentre, cross-sectional, observational study. Helicobacter pylori cultures were successful in 600 patients (never receiving eradication therapy) from Northern, Eastern, Middle, and Southern regions between 2008 and 2012. Resistance to amoxicillin, clarithromycin, metronidazole, levofloxacin, tetracycline, and rifampicin was determined by Epsilometer test. ResultsThe overall resistance rate was highest for metronidazole (403, 67.2%), followed by clarithromycin (225, 37.5%), levofloxacin (201, 33.5%), rifampicin (85, 14.2%), amoxicillin (41, 6.8%), and tetracycline (21, 3.5%). There were 16.3% isolates susceptible to all tested antibiotics, followed by mono-resistance (34.2%), double resistance (27.0%), triple resistance (16.8%), quadruple resistance (4.7%), quintuple resistance (0.7%) and sextuple resistance (0.3%). Independent factors influencing antibiotic resistance were gender (to levofloxacin), age (to levofloxacin), and endoscopic finding (to clarithromycin, metronidazole, and levofloxacin). Among the clarithromycin-resistant isolates, 75.6% and 48.0% were also resistant to metronidazole and levofloxacin, respectively. ConclusionsHelicobacter pylori resistance to commonly used antibiotics in China is a very serious issue, due to the high resistance rate and general multiple resistance.

Heterocoagulation of polysaccharide-coated platinum nanoparticles with ovarian-cancer cells

Platinum nanoparticles coated with adsorption layers of polysaccharides of Chlorella vulgaris (PtPS) have been synthesized and their heterocoagulation with human ovarian-cancer cells of the A2780 line has been studied. It has been shown that the characteristic time of the aggregation of the cells with PtPS nanoparticles is 20–25 min, which corresponds to fast barrierless coagulation. The cytotoxic effect of PtPS nanoparticles reaches saturation and more than 50% of the cells die within this time period. Cytomorphological investigations have shown that A2780 cells with doubled resistance to an antitumoral antibiotic, doxorubicin, are more sensitive to the toxic action of PtPS nanoparticles than nonresistant cells are. An electrokinetic control test has been proposed for cancer-cell resistance based on the measurement of variations in the ζ-potential of nanoparticles due to adsorption of water-soluble metabolites of the cells on a particle surface.

Quantitative Identification of Reservoir Fracture with the Variable Scale Fractal Technique in Su53 Gas Field, Ordos Basin

Typical tight gas reservoirs in the Su53 Gas Field, Ordos Basin, are the demonstration region for deploying horizontal wells. In order to provide foundation for evaluating the volume fracturing adaptability of horizontal wells, through using the amplitude difference data between deep investigate double lateral resistivity (Rd) and shallow investigate double lateral resistivity (Rs), and other conventional logging data, in combination with the response characteristics of fracture in the logging curve, reservoir fracture was quantitatively identified with the variable scale fractal technique, the vertical heterogeneity of fracture distribution was analyzed, and the relationship between fractal dimension value of fracture and initial deliverability of gas well was researched. The results indicate that, this method is applied to quantitatively identify and evaluate the fracture development degree of single-well is feasible; the relationship between fractal dimension value and fracture development degree is positively relative, fractal dimension value is bigger, the fracture is more developed; there is a good corresponding relationship between fractal dimension value and deliverability of gas well, fractal dimension value decreases with a decrease of deliverability.

Fungicide resistance of Botrytis cinerea in tomato greenhouses in the Canary Islands and effectiveness of non-chemical treatments against gray mold.

Tomato greenhouses in the Canary Islands, Spain, were surveyed to estimate frequencies of resistance to benzimidazoles, dicarboximides, anilinopyrimidines and N-phenylcarbamates in Botrytis cinerea. Resistance to carbendazim, iprodione, pyrimethanil and diethofencarb was found in 74.2, 86.4, 28.8 and 31.8% of isolates, respectively. Benzimidazole- and anilinopyrimide-resistant isolates were highly resistant, showing EC50 values above 500 µg/ml carbendazim and a mean EC50 value of 28.42 µg/ml pyrimethanil, respectively. By contrast, a low level of resistance was observed among dicarboximide-resistant isolates (mean EC50 value of 1.81 µg/ml iprodione). Phenotypes with double resistance to carbendazim and iprodione, and triple resistance to carbendazim, iprodione and pyrimethanil were the most common, occurring in 36.4 and 28.8% of isolates. The surveyed greenhouses had never been treated with fenhexamid and Signum™ (pre-packed mixture of boscalid and pyraclostrobin), and baseline sensitivities of B. cinerea isolates to these fungicides were determined. The EC50 values were within the range of 0.009-0.795 µg/ml fenhexamid and of 0.014-0.48 µg/ml Signum. In addition, available formulations based on elicitors of plant defense response and biocontrol agents were evaluated against B. cinerea in tomato plants under semi-controlled greenhouse conditions, the yeast Candida sake CPA-1 being able to reduce gray mold significantly when it was applied on petiole wounds and the plants were inoculated 24 h later. Likewise, C. sake was effective against B. cinerea in harvested tomato fruits, yeast-treated tomatoes showed a 70.66 and 30.31% reduction in the diameters of decay lesions compared with controls after 10 days of storage at 20 and 9 °C, respectively.

AC impedance spectroscopy investigation of carbon supported Pt3Co and Pt cathode catalysts in direct methanol fuel cell

The performance of direct methanol fuel cells containing carbon supported Pt3Co and Pt cathode catalysts with 3 nm crystallite size was investigated by AC electrochemical impedance spectroscopy under load. The electrochemical investigations were carried out at 40 °C and as a function of the cell voltage, oxygen vs. air feed, gas flow rate and methanol concentration. From the response of the total impedance spectra to the tested parameters, simple equivalent circuits were built and used to fit the complete DMFC impedance spectra. The electrochemical parameters (charge transfer resistance, double layer capacitance, relaxation resistance and relaxation inductance for the adsorbed species) associated with the oxygen reduction and methanol poisoning effects were determined. The AC impedance study confirmed the lower methanol tolerance of Pt3Co catalyst compared to the Pt catalyst.

Upregulation of the Saccharomyces cerevisiae efflux pump Tpo1 rescues an Imp2 transcription factor‐deficient mutant from bleomycin toxicity

Yeast mutants lacking the transcriptional co-activator Imp2 are hypersensitive to the anticancer drug bleomycin, although the gene targets involved in this process remain elusive. A search for multicopy suppressors that rescue the imp2Δ mutant from bleomycin toxicity revealed the transcriptional activator Yap1, which can turn on many target genes such as transporters involved in regulating drug resistance. We show that YAP1 overexpression stimulated the expression of the TPO1 gene encoding a polyamine efflux pump, and that Yap1 failed to rescue the imp2Δ mutant from bleomycin toxicity in the absence of the TPO1 gene. Moreover, TPO1 overexpression, and not the related transporter gene QDR3, conferred upon the tpo1Δ imp2Δ double mutant parental resistance to bleomycin. We conclude that YAP1 overexpression rescues the imp2Δ mutant from bleomycin toxicity by triggering Tpo1 expression to expel the drug. Our data provide the first evidence that bleomycin could be a substrate for the Tpo1 efflux pump.

Prevelance of Common YMDD Motif Mutations in Long Term Treated Chronic HBV Infections in a Turkish Population

In the current study we aimed to show the common YMDD motif mutations in viral polymerase gene in chronic hepatitis B patients during lamivudine and adefovir therapy. Forty-one serum samples obtained from chronic hepatitis B patients (24 male, 17 female; age range: 34-68 years) were included in the study. HBV-DNA was extracted from the peripheral blood of the patients using an extraction kit (Invisorb, Instant Spin DNA/ RNA Virus Mini Kit, Germany). A line probe assay and direct sequencing analyses (INNO-LIPA HBV DR v2; INNOGENETICS N.V, Ghent, Belgium) were applied to determine target mutations of the viral polymerase gene in positive HBV-DNA samples. A total of 41 mutations located in 21 different codons were detected in the current results. In 17 (41.5%) patients various point mutations were detected leading to lamivudin, adefovir and/ or combined drug resistance. Wild polymerase gene profiles were detected in 24 (58.5%) HBV positive patients of the current cohort. Eight of the 17 samples (19.5%) having rtM204V/I/A missense transition and/or transversion point mutations and resistance to lamivudin. Six of the the mutated samples (14.6%) having rtL180M missense transversion mutation and resistance to combined adefovir and lamivudin. Three of the mutated samples (7.5%) having rtG215H by the double base substituation and resistance to adefovir. Three of the mutated samples (7.5%) having codon rtL181W due to the missense transversion point mutations and showed resistance to combined adefovir and lamivudin. Unreported novel point mutations were detected in the different codons of polymerase gene region in the current HBV positive cohort fromTurkish population. The current results provide evidence that rtL180M and rtM204V/I/A mutations of HBV-DNA may be associated with a poor antiviral response and HBV chronicity during conventional therapy in Turkish patients.

Epidemiological control of drug resistance and compensatory mutation under resistance testing and second-line therapy

The fitness cost of antibiotic resistance in the absence of treatment raises the possibility that prudent use of drugs may slow or reverse the rise of resistance. Unfortunately, compensatory mutations that lower this cost may lead to entrenched resistance. Here, we develop a mathematical model of resistance evolution and compensatory mutation to determine whether reversion to sensitivity can occur, and how disease control might be facilitated by a second-line therapy. When only a single antibiotic is available, sensitive bacteria reach fixation only under treatment rates so low that hardly any cases are treated. We model a scenario in which drug sensitivity can be accurately tested so that a second-line therapy is administered to resistant cases. Before the rise of resistance to the second drug, disease eradication is possible if resistance testing and second-line treatment are conducted at a high enough rate. However, if double drug resistance arises, the possibility of disease eradication is greatly reduced and compensated resistance prevails in most of the parameter space. The boundary separating eradication from fixation of compensated resistance is strongly influenced by the underlying basic reproductive number of the pathogen and drug efficacy in sensitive cases, but depends less on the resistance cost and compensation. When double resistance is possible, the boundary is affected by the relative strengths of resistance against the two drugs in the double-resistant-compensated strain.

Marker assisted introgression of multiple genes for bacterial blight resistance into aromatic Myanmar rice MK-75

Bacterial blight disease (BB) caused by Xanthomonas oryzae pv. oryzae (Xoo) is a major threat to rice yield in rainfed and irrigated lowland ecosystems in Myanmar. Large-scale and long-term cultivation of released Myanmar rice varieties have continuously caused the outbreak of BB since 1983. In this study, a high yielding Manawthukha rice line ‘Yn 3248-2-128-76-4-3-75’ (MK-75) with fragrance and intermediate amylose content was used as a recipient parent to improve its resistance to BB. RGDU-07097-1-8M-9 (RG-9), an improved line carrying xa5, Xa21 and xa33 was used as the donor parent. Resistant alleles of xa5, Xa21 and xa33 from RG-9 were successfully transferred into MK-75 by using marker-assisted backcrossing (MAB) method while maintaining the cooking quality of MK-75. Twenty eight selected BC3F2 introgression lines (MK-75 ILs) carrying different combinations of these three loci were tested for BB resistance at seedling and maximum tillering stages against ten Thai and five Myanmar Xoo strains. The triple and double resistance gene-introgressed lines (xa5Xa21xa33 or xa5Xa21 or xa5xa33 or Xa21xa33) had higher level of resistance and wider resistance spectrum than MK-75 against both Thai and Myanmar Xoo strains. The single resistance gene-introgressed lines carrying xa5 had higher resistance against Thai Xoo strains, while lines carrying Xa21 showed higher level of resistance to Myanmar Xoo strains. These results clearly indicated that pyramiding of multiple genes is a useful approach for improving BB resistance in MK-75. All ILs had physical grain quality, fragrance and amylose content similar to MK-75. Thus the improvement of BB resistance in MK-75 may have a wide range of benefits in breeding program and should be immediately useful in areas where original Manawthukha, the progenitor or MK-75 is widely grown.

Theory of asymmetric electrochemical stochastic diffusion

Strict analysis of electrochemical strochastic diffusion due to asymmetric Brownian motion of electric charge in an equilibrium electrochemical ac circuit containing double electric layer capacitance and noisy Faradaic resistance is carried out. Cumulant analogs (for 3rd and 5th order correlations) of the Einstein formula are obtained. It is proved that equilibrium asymmetric (nongauss) stochastic diffusion is in agreement with the central limiting theorem of the probability theory. The Hurst exponent was found in the case of the nongauss components of the process of equilibrium stochastic diffusion. Apart from electrochemistry, the performed stochastic analysis of equilibrium electrochemical nongauss diffusion is also of general theoretical interest, including its application in the stochastic theory of asymmetric anomalous transport and strict theory of fluctuations at large deviations from equilibrium.

Prevention of water and quicksand inrush during extracting contiguous coal seams under the lowermost aquifer in the unconsolidated Cenozoic alluvium—a case study

Extracting the contiguous coal seams under the lowermost aquifer in the unconsolidated Cenozoic alluvium is apt to water and quicksand inrush. By using a series of investigation methods including empirical formulas, numerical simulation, theoretical analysis, etc., the study focused on the fracture and the excess pore water pressure in the overlying strata in the process of extracting no. 8 coal seam firstly and no. 9 coal seam (under no. 8 coal seam) subsequently in no. 8102 working face of Luling coal mine in the north of Anhui Province of China. When no. 8 coal seam was extracted, the water-conducting fractured zone penetrated into the lowermost aquifer and rapid dissipation of excess pore water pressure above the gob occurred, accompanied by relatively high seepage hydraulic gradient over the headgate and the tailgate. When no. 9 coal seam was extracted, failure did not obviously extend upwards and the excess pore water pressure decreased slowly and a relatively high seepage hydraulic gradient transferred downwards from the headgate to the tailgate in the inclined profile. The safe water head (H s) in the lowermost aquifer was confirmed to 15.6 m. Therefore, water and quicksand inrush was avoided effectively in the process of extracting the contiguous coal seams by dewatering, controlling mining height, and laying double resistance nets in the working face.

Performance and characteristics of double layer porous silicon oxide resistance random access memory

A bilayer resistive switching memory device with an inserted porous silicon oxide layer is investigated in this letter. Compared with single Zr:SiOx layer structure, Zr:SiOx/porous SiOx structure outperforms from various aspects, including low operating voltages, tighter distributions of set voltage, higher stability of both low resistance state and high resistance state, and satisfactory endurance characteristics. Electric field simulation by comsolTM Multiphysics is applied, which corroborates that intensive electric field around the pore in porous SiOx layer guides the conduction of electrons. The constraint of conduction path leads to better stabilization and prominent performance of bilayer resistive switching devices.

Esomeprazole-based sequential therapy and probiotic for Helicobacter pylori eradication

PURPOSE: The objective of the present study was to determine the effectiveness of esomeprazole-based sequential therapy and Bio Gaya probiotic for the treatment of Helicobacter pylori-infection (Hp-infection) with associated gastro duodenal diseases. MATERIAL AND METHODS: The study covered 104 patients with dominating upper dyspeptic syndrome and Hp-infection examined by means of two or more methods. Esomeprazole-based sequential therapy consisted in amoxicillin in a dose of 1.0 g two times daily for the first five days followed by clarithromycin and metronidazole in a dose of 500 mg two times daily for the next 5 days. A Bio Gaya probiotic was added during the 10-day treatment. RESULTS: Hp-infection was successfully treated in 98 patients (94.2%) and in 79 out of 81 naive ones (97% of the cases). This therapy proved effective in 19 out of 23 patients (82.6%) after one or two failed Hp-infection eradications, too. The treatment failed in 6 patients (5.7%) because of a double antibiotic resistance. CONCLUSION: The esomeprazole-based sequential therapy and Bio Gaya probiotic represented a highly and well-tolerable effective eradication option. Clinical symptoms and quality of life were favourable influenced in all the patients as well as side effects were rare. Scripta Scientifica Medica 2013; 45(2): 61-65.