Individual Fracture Efficiency Monitoring in Horizontal Wells by Using a New 3d Fine-Grid Temperature Modelling

Profitable development of hard-to-recover reserves often involves drilling of horizontal wells with multistage hydraulic fracturing to increase the oil recovery factor. Usually to monitor the fracture sweep efficiency, pressure transient analysis is used. However, in case of several fractures this method delivers only average hydrodynamic parameters of the well-fracture system. This paper illustrates the value of temperature logging data and demonstrates possibilities of the 3-D thermo-mechanical modelling in evaluating the differential efficiency of multi-stage hydraulic fracturing.

Determination of ballistic resistance of cementitious composites

The paper describes the possibility of using the DOP test, standardly used to evaluate the ballistic resistance of ceramics, to determine the ballistic resistance of cement composites. DOP - Depth of penetration test - is based on measurement of residual penetration of projectile in witness system after the sample perforation; this parameter is used to determine differential efficiency factor (DEF), characterizing the ballistic resistance of the particular material. To verify the method for non-ceramic materials, four variants of cementitious composites with compressive strengths in the range of 30–150 MPa have been tested. The obtained results confirm the method’s suitability for determining the ballistic resistance of cement composites in terms of ease of implementation, sensitivity, and accuracy of the obtained results for both composites of common strengths and high-performance variants. The paper also discusses some aspects of the relationship between the mechanical parameters of cement composites under static loading and their ballistic resistance.

Production of p-cresol by Decarboxylation of p-HPA by All Five Lineages of Clostridioides difficile Provides a Growth Advantage

Clostridioides difficile is the leading cause of antibiotic-associated diarrhea and is capable of causing severe symptoms, such as pseudomembranous colitis and toxic megacolon. An unusual feature of C. difficile is the distinctive production of high levels of the antimicrobial compound para-cresol. p-Cresol production provides C. difficile with a competitive colonization advantage over gut commensal species, in particular, Gram-negative species. p-Cresol is produced by the conversion of para-hydroxyphenylacetic acid (p-HPA) via the actions of HpdBCA decarboxylase coded by the hpdBCA operon. Host cells and certain bacterial species produce p-HPA; however, the effects of p-HPA on the viability of C. difficile and other gut microbiota are unknown. Here we show that representative strains from all five C. difficile clades are able to produce p-cresol by two distinct mechanisms: (i) via fermentation of p-tyrosine and (ii) via uptake and turnover of exogenous p-HPA. We observed strain-specific differences in p-cresol production, resulting from differential efficiency of p-tyrosine fermentation; representatives of clade 3 (CD305) and clade 5 (M120) produced the highest levels of p-cresol via tyrosine metabolism, whereas the toxin A-/B+ isolate from clade 4 (M68) produced the lowest level of p-cresol. All five lineages share at least 97.3% homology across the hpdBCA operon, responsible for decarboxylation of p-HPA to p-cresol, suggesting that the limiting step in p-cresol production may result from tyrosine to p-HPA conversion. We identified that elevated intracellular p-HPA, modulated indirectly via CodY, controls p-cresol production via inducing the expression of HpdBCA decarboxylase ubiquitously in C. difficile populations. Efficient turnover of p-HPA is advantageous to C. difficile as p-HPA has a deleterious effect on the growth of C. difficile and other representative Gram-negative gut bacteria, transduced potentially by the disruption of membrane permeability and release of intracellular phosphate. This study provides insights into the importance of HpdBCA decarboxylase in C. difficile pathogenesis, both in terms of p-cresol production and detoxification of p-HPA, highlighting its importance to cell survival and as a highly specific therapeutic target for the inhibition of p-cresol production across C. difficile species.

Анализ пороговых условий и эффективности генерации замкнутых мод в больших прямоугольных резонаторах на основе лазерных гетероструктур AlGaAs/GaAs/InGaAs

Threshold conditions and efficiency analsis of a semiconductor laser emitter with a large (1x1mm) rectangular resonator based on AlGaAs/GaAs/ InGaAs heterostructures for high-power strip lasers operating on high-Q internally circulating structures is presented. Two designs of emitters with different laser radiation propagation region characteristics are proposed, and the possibility of differential efficiency characteristic as high as high-power broad lasers (70% and more) is demonstrated.

Selective translation by alternative bacterial ribosomes

Alternative ribosome subunit proteins are prevalent in the genomes of diverse bacterial species, but their functional significance is controversial. Attempts to study microbial ribosomal heterogeneity have mostly relied on comparing wild-type strains with mutants in which subunits have been deleted, but this approach does not allow direct comparison of alternate ribosome isoforms isolated from identical cellular contexts. Here, by simultaneously purifying canonical and alternative RpsR ribosomes fromMycobacterium smegmatis, we show that alternative ribosomes have distinct translational features compared with their canonical counterparts. Both alternative and canonical ribosomes actively take part in protein synthesis, although they translate a subset of genes with differential efficiency as measured by ribosome profiling. We also show that alternative ribosomes have a relative defect in initiation complex formation. Furthermore, a strain ofM. smegmatisin which the alternative ribosome protein operon is deleted grows poorly in iron-depleted medium, uncovering a role for alternative ribosomes in iron homeostasis. Our work confirms the distinct and nonredundant contribution of alternative bacterial ribosomes for adaptation to hostile environments.

Overinformative speakers are cooperative: Revisiting the Gricean Maxim of Quantity

A pragmatic account of referential communication is developed which presents an alternative to traditional Gricean accounts by focusing on cooperativeness and efficiency, rather than informativity. The results of four language-production experiments support the view that speakers can be cooperative when producing redundant adjectives, doing so more often when color modification could facilitate the listener’s search for the referent in the visual display (Experiment 1a). By contrast, when the listener knew which shape was the target, speakers did not produce redundant color adjectives (Experiment 1b). English speakers used redundant color adjectives more often than Spanish speakers, suggesting that speakers are sensitive to the differential efficiency of prenominal and postnominal modification (Experiment 2). Speakers were also cooperative when using redundant size adjectives (Experiment 3). Overall, these results show how discriminability affects a speaker’s choice of referential expression above and beyond considerations of informativity, supporting the view that redundant speakers can be cooperative.

Investigation of Ce-=SUP=-3+-=/SUP=- impurity centers in UV active media Ce:LiCaAlF-=SUB=-6-=/SUB=- and Ce:LiSr-=SUB=-0.8-=/SUB=-Ca-=SUB=-0.2-=/SUB=-AlF-=SUB=-6-=/SUB=- -=SUP=-*-=/SUP=-

Fluoride crystals with the colquiriite structure LiCaAlF6 doped with Ce3+ ions are used as active media for lasers of ultraviolet spectral range with advantages of laser wavelength tuning range and no photoinduced degradation of laser properties. In this work we show that the multicenter character of Ce3+ segregation in this matrix agrees with the previously known peculiarities. On the basis of spectral-kinetic properties investigation, we show the increase of segregation coefficient for Ce3+ in LiSr0.8Ca0.2AlF6 mixed crystal. In laser experiments with Ce : LiCaAlF6 crystal, the differential efficiency of 47% and the wavelength tuning from 281 to 312 nm have been reached.

Температурная зависимость характеристик полупроводниковых лазеров с узкими квантовыми ямами спектрального диапазона 1.55 μm на основе бесфосфорных гетероструктур

The InGaAs/InGaAlAs laser diodes of the 1.55-μm spectral range were studied. It is shown that carbon doping at the level of 1012 cm-2 per quantum well makes it possible in these laser structures to reduce the temperature coefficient of lasing wavelength variation, as well as to increase the characteristic temperatures of the threshold current and differential efficiency in the temperature range from 16°C to about 50°C while simultaneously increasing the threshold density current and reducing the differential efficiency.