Jet array impingement flow distributions and heat transfer characteristics. Effects of initial crossflow and nonuniform array geometry

Two-dimensional arrays of circular air jets impinging on a heat transfer surface parallel to the jet orifice plate are considered. The jet flow, after impingement, is constrained to exit in a single direction along the channel formed by the jet orifice plate and the heat transfer surface. The configurations considered are intended to model those of interest in current and contemplated gas turbine airfoil midchord cooling applications. The effects of an initial crossflow which approaches the array through an upstream extension of the channel are considered. Flow distributions as well as heat transfer coefficients and adiabatic wall temperatures resolved to one streamwise hole spacing were measured as a function of the initial crossflow rate and temperature relative to the jet flow rate and temperature. Both Nusselt number profiles and dimensionless adiabatic wall temperature (effectiveness) profiles are presented and discussed. Special test results which show a significant reduction of jet orifice discharge coefficients owing to the effect of a confined crossflow are also presented, along with a flow distribution model which incorporates those effects. A nonuniform array flow distribution model is developed and validated

Notes on the habitats of some tropical species of Hetaerina (Odonata)

http://deepblue.lib.umich.edu/bitstream/2027.42/56569/1/OP130.pd

Customer premise service study for 30/20 GHz satellite system

Satellite systems in which the space segment operates in the 30/20 GHz frequency band are defined and compared as to their potential for providing various types of communications services to customer premises and the economic and technical feasibility of doing so. Technical tasks performed include: market postulation, definition of the ground segment, definition of the space segment, definition of the integrated satellite system, service costs for satellite systems, sensitivity analysis, and critical technology. Based on an analysis of market data, a sufficiently large market for services is projected so as to make the system economically viable. A large market, and hence a high capacity satellite system, is found to be necessary to minimize service costs, i.e., economy of scale is found to hold. The wide bandwidth expected to be available in the 30/20 GHz band, along with frequency reuse which further increases the effective system bandwidth, makes possible the high capacity system. Extensive ground networking is required in most systems to both connect users into the system and to interconnect Earth stations to provide spatial diversity. Earth station spatial diversity is found to be a cost effective means of compensating the large fading encountered in the 30/20 GHz operating band

Morbidity and mortality risk factors after surgery of perforations by colonoscopy

RESUMEN : INTRODUCCIÓN. La colonoscopia es un procedimiento utilizado frecuentemente en la práctica clínica para el diagnóstico, tratamiento y seguimiento de patologías digestivas que afectan al colon y recto. Aunque es considerada una técnica segura, la realidad es que no se está exenta de riesgos y complicaciones, algunas de las cuales suponen una importante morbilidad, e incluso pueden causar la muerte del paciente. OBJETIVOS. El objetivo de este estudio es describir las características clínicas y demográficas de un grupo de pacientes intervenidos quirúrgicamente por una perforación de colon tras una colonoscopia diagnóstica y/o terapéutica y tratar de identificar qué factores de riesgo aumentan la morbi-mortalidad. PACIENTES Y MÉTODOS. Estudio retrospectivo de revisión de historias clínicas que incluye 97 pacientes con perforación iatrogénica por colonoscopia intervenidos quirúrgicamente para su resolución en el Hospital Universitario “Marqués de Valdecilla” durante el periodo comprendido entre febrero de 1995 y diciembre de 2019. Se analiza la morbi-mortalidad tras el tratamiento quirúrgico de la perforación. RESULTADOS. El 69,1% de las colonoscopias fueron terapéuticas. La indicación más frecuente fue el cribado del cáncer colorrectal (21,9%) seguida de la hemorragia digestiva (19,7%). El lugar más frecuente de la perforación fue el sigma (55,3%). Hubo morbilidad en el 39,8% de los casos y mortalidad en el 9,2%. La morbilidad fue significativamente mayor en los pacientes mayores de 70 años (p=0,045), así como la necesidad de ingreso en UCI (p=0,013) y la estancia postoperatoria (p=0,02). La mortalidad fue significativamente mayor en los pacientes con un índice ASA más elevado (p<0,001). CONCLUSIONES. La edad superior a 70 años, así como una clasificación ASA preoperatoria elevada se asocian de manera significativa a una mayor morbi-mortalidad postoperatoria, a una mayor estancia postoperatoria y necesidad de ingreso en UCI.ABSTRACT : BACKGROUND. Colonoscopy is a procedure frequently used in clinical practice for the diagnosis, treatment, and monitoring of digestive pathologies that affect the colon and rectum. Although it is considered a safe technique, the reality is that it is not exempt from risks and complications, some of which involve significant morbidity, and may even cause the death of the patient. AIM OF STUDY. The objective of this study is to describe the clinical and demographic characteristics of a group of patients who underwent surgery for colon perforation after diagnostic and/or therapeutic colonoscopy and try to identify risk factors that increase morbi-mortality. PATIENTS AND METHODS. Retrospective review of medical records that includes 97 patients with iatrogenic perforation by colonoscopy who underwent surgery for resolution at University Hospital “Marqués de Valdecilla” during the period between February 1995 and December 2019. Morbidity and mortality after surgical treatment of perforation are analized. RESULTS. 69.1% of colonoscopies were therapeutic. The most common indication was screening for colorectal cancer (21.9%) followed by gastrointestinal bleeding (19.7%). The most common location for perforation was sigma (55.3%). There was morbidity in 39.8% of cases and mortality in 9.2%. Morbidity was significantly higher in patients older than 70 years (p = 0.045), as well as the need for ICU admission (p = 0.013) and postoperative stay (p = 0.02). Mortality was significantly higher in patients with a higher ASA index (p <0.001). CONCLUSIONS. Age over 70 years as well as a high preoperative ASA classification are significantly associated with a greater postoperative morbidity and mortality, a longer postoperative stay and need for ICU admission.Grado en Medicin

Elucidation of the Putative Gene Cluster for the Biosynthesis of Siphonazole – a Secondary Metabolite from <em>Herpetosiphon</em>

Polyketides (PKs) and non-ribosomal peptides (NRPs) are two major classes of natural products. They comprise a vast variety of structurally and functionally diverse compounds, which include a great number of clinically important substances. These metabolites are the product of giant multienzymes termed polyketide synthases (PKSs) and non-ribosomal peptide synthetases (NRPSs), respectively. The present study investigated the putative biosynthetic gene cluster of siphonazole. This compound is produced by the Herpetosiphon strain 060, which belongs to the deep rooted phylum of Chloroflexi, and is the first secondary metabolite described from this group. Siphonazole is composed of building blocks derived from acetate, amino acid and shikimate pathways. The gross structure comprises a styrene moiety, two oxazole rings connected by a C2-bridge and an unusual diene side chain. Genomic DNA of Herpetosiphon sp. 060 was subjected to 454 sequencing yielding draft genomic data of the strain. The application of bioinformatics and molecular biological techniques led to the identification of a hybrid NRPS/PKS gene cluster with ten open reading frames (sphA – sphJ), which encode the putative enzymes for the biosynthesis of siphonazole. Through a detailed bioinformatic analysis, it was revealed that the encoded proteins include eight PKS modules, which are assumably all loaded in trans by the acyltransferase (AT) SphA, and four NRPS modules. The AT has a predicted specificity for malonyl-CoA. Two of the NRPS units are heterocyclisation modules, which are responsible for the formation of the oxazole rings from threonine moieties. The first NRPS module initiates the biosynthesis probably by incorporation of a dihydroxybenzoic acid. In vitro studies with purified protein showed that the potential precursor molecule protocatechuic acid is readily methylated by the O-methyltransferase SphB. The analysis of total mRNA from Herpetosiphon by RT-PCR revealed that sphA – sphJ are only expressed in the first three days of cultivation. In agreement with this early gene expression, the application of imaging mass spectrometry showed that siphonazole is located exclusively at the edge of a growing colony. On the basis of the obtained sequence information, cluster fragments of three overlapping fosmids from a genomic library were successfully recombined by λ-Red recombination methods. Thus, a fosmid construct of 71 kb was generated harbouring genes sphA – sphJ

DNA translocases and origin region segregation in B. subtilis

Specialized mechanisms involved in chromosome segregation, septum placement, and chromosome dimer resolution contribute to the maintenance of chromosome integrity throughout the cell cycle. The first part of this work focuses on the investigation of DNA translocases in the Gram positive model organism Bacillus subtilis, which move the chromosomes away from the division plane by directed DNA transport. SpoIIIE is a membrane-integral translocase that also acts during sporulation, while SftA is associated with the division septum by an unknown mechanism and was reported to be a soluble protein in vitro. The solubility of SftA in vivo was proven with cell fractionation experiments, and the part of the protein that serves for septal targeting was determined through the localization of different truncations of fluorescently labeled SftA, which helped narrow down the stretch of amino acids responsible for targeting the protein to the septum. Expression in a Eukaryotic heterologous system revealed an interaction between SftA and FtsA, but not FtsZ. Further evidence was provided by single molecule tracking experiments whereby the fraction of soluble SftA molecules increased in an FtsA depletion background as compared to a wild type background. Concomitant investigation on the single molecule level of SpoIIIE, a membrane associated DNA translocase in B. subtilis, and PfkA, a soluble phosphofructokinase, revealed a different behavior of the two translocases (SftA and SpoIIIE): SftA has a septal bound fraction, and a small soluble fast moving fraction,comparable in diffusion coefficient to the exclusively soluble PfkA tracked under the same conditions. SpoIIIE is much slower in comparison, and even its “fast” moving fraction is much slower than that of SftA. It seems to move slowly along the membrane with no specific enrichment at the septum, even after Mitomycin C (MMC) treatment. The second part of this work focused on the count of nucleoids, origin, and terminus of replication regions under conditions of fast and slow growth, with or without the induction of double strand breaks with MMC. B. subtilis seemed to be predominantly diploid, with a fraction of polyploid and monoploid cells which changed depending on the growth conditions. Replication of the origin proximal regions increased after DNA damage induction, as was shown by the increase in the number of origins during the time of DNA repair, while the number of termini remained constant. Time lapse experiments of the segregation of the tagged origin regions revealed that the movement is best described as directed diffusion, but seems to be quite robust and continues, though slower, after MMC treatment or treatment with Ciprofloxacin which blocks the topoisomerase I

Chorismate synthase from Staphylococcus aureus

The aroC gene encoding chorismate synthase and the ndk gene encoding nucleoside diphosphate kinase were cloned from Staphylococcus aureus by complementation of the Aro- phenotype of the aroC E. coli strain, GLW40. Two partial open reading frames (ORFs) encoding 3-dehydroquinate synthase and a protein which had similarity with the putative gerCC gene product from B. subtilis were also cloned. In S. aureus the aroC gene is likely to form the first gene in an operon which includes the aroB and aroA genes. It has been demonstrated in this study that the ndk genes and the gerCAgerCBgerCC genes in S. aureus are situated upstream from the aroCaroB genes; this gene organisation has also been observed in B. subtilis. The S. aureus aroC gene was expressed from the T7 promoter on plasmid pTB361. This expression system resulted in the accumulation of very high levels of soluble S. aureus chorismate synthase and facilitated the purification of the enzyme to near homogeneity, producing 100mg of enzyme from 13g of cells. No detectable immunological crossreactivity was observed between S. aureus chorismate synthase and antibodies raised against E. coli chorismate synthase. This contrasts with other chorismate synthases and indicates that there are structural differences between the chorismate synthases from S. aureus and E. coli. S. aureus chorismate synthase was determined to be a homotetramer using gel filtration and chemical crosslinking. The pH optimum determined for S. aureus chorismate synthase was found to be non-symmetrical in MOPS buffer with an optimum of activity around pH 7.0. The apparent Km for EPSP of the S. aureus enzyme was calculated to be 12.7muM and the apparent Km for FMN was calculated to be 4.8muM. The apparent Km value for FMN for the S. aureus enzyme is two orders of magnitude greater compared to other chorismate synthases, excluding the B. subtilis enzyme. S. aureus chorismate synthase was investigated using pre-steady state kinetics and a flavin intermediate was observed during turnover with a difference spectrum resembling that obtained with the E. coli enzyme. The spectral characteristics of the S. aureus flavin intermediate were different, however, with respect to its maxima, minima and its overall shape. The rate of decay (6.5s-1) of the intermediate was eight times slower than that observed for the E. coli enzyme (52s-1) and this compares well with a 7 fold lower Vmax. Tyrosine 121 of S. aureus chorismate synthase was changed to phenylalanine or alanine using site-directed mutagenesis. The conversion to alanine resulted in a loss of activity while the phenylalanine mutant retained 10% of wild-type activity