bluuebunny/crossref_metadata_2025 huggingface dataset:
IL‐17 downregulates filaggrin and affects keratinocyte expression of genes associated with cellular adhesion
Authors: Gutowska‐Owsiak Danuta , Schaupp Anna L. , Salimi Maryam , Selvakumar Tharini A. , McPherson Tess , Taylor Stephen , Ogg Graham S.
Published: November 2011

Abstract:  Atopic eczema and psoriasis are common skin diseases. While it is well established that the pathogenesis of these diseases varies, both are characterized by impairment in epidermal barrier function and abnormal IL‐17 expression in the skin and peripheral blood. Recent findings indicated that filaggrin is essential during barrier formation and its insufficiency underlies the pathogenesis of atopic eczema. Filaggrin downregulation has also been reported in psoriasis. It is clear that Th1/Th2 bias influences expression of the protein, but an analysis of the effects of interleukin‐17 (IL‐17) on the expression of the protein and profilaggrin‐processing enzymes has not yet been reported. In addition, the effect of the cytokine on components of functional epidermal barrier, tight junctions and adhesion/desmosomal proteins, has not been elucidated. Keratinocytes were exposed to interleukin‐17A, and microarray analysis was performed. Filaggrin protein level was assessed by western blot. We have observed a significant decrease in profilaggrin mRNA level in interleukin‐17A‐exposed cultures (P = 0.008). Expression of processing enzymes was also altered, indicating an indirect effect of the cytokine on filaggrin production/degradation. Moreover, expression of many genes involved in cellular adhesion was also decreased. A significant downregulation of filaggrin at the protein level was detected by western blot in immortal and primary keratinocytes. Gene ontology analysis indicated changes in keratinization, epidermal differentiation and formation of the cornified envelope. We conclude that IL‐17A downregulates the expression of filaggrin and genes important for cellular adhesion which could affect epidermal barrier formation. This effect potentially contributes to barrier dysfunction and could become a possible therapeutic target.
Species‐specific mediation of temperature and community interactions by multiple foundation species
Authors: Dijkstra Jennifer A. , Boudreau Jacqueline , Dionne Michele
Published: November 2011

Foundation species can provide habitat that modify abiotic and biotic processes that contribute to ecosystem function. While many studies have focused on the processes and consequences of a focal foundation species, understanding the ecological equivalence of co‐occurring foundation species is important to identify key species responsible for ecosystem function. Here, we investigated the relative contributions of co‐occurring foundation species on abiotic (temperature) and biotic responses of invertebrate species (recruitment, persistence, growth and survival). In a series of experimental field studies, we manipulated foundation species to measure invertebrate recruitment, persistence, and predation. A laboratory experiment measured foundation species effects on herbivore growth. Results demonstrated that macroalgal (Fucus vesiculosus ecad and Ascophyllum nodosum ecad scorpioides) intermediate foundation species provide habitat, food, and alleviate abiotic stress for dominant littorinid herbivores that surpass that provided by the primary species (Spartina alterniflora). These foundation effects were species‐specific with F. vesiculosus ecad important for early life‐history stages (enhanced recruitment and early growth of littorinid snails) and A. nodosum ecad important later on as a refuge from predators (Carcinus meanas) and stressful temperature. Understanding of the different effects of co‐occurring foundation species on population and community processes is necessary for predicting community response to natural disturbance, species invasion, and ecosystem‐based management actions.
Increased Na+,K+-ATPase activity in the rat brain after meningitis induction byStreptococcus pneumoniae
Authors: Barichello Tatiana , Generoso Jaqueline S. , Cipriano Andreza L. , Casagrande Renata , Collodel Allan , Savi Geovana D. , Scherer Emilene B. S. , Kolling Janaína , Wyse Angela T. S.
Published: November 2011

Barichello T, Generoso JS, Cipriano AL, Casagrande R, Collodel A, Savi GD, Scherer EBS, Kolling J, Wyse ATS. Increase Na+,K+-ATPase activity in the rat brain after meningitis induction byStreptococcus pneumoniae.

Background: Pneumococcal meningitis is the most severe infection of the central nervous system with a mortality rate up to 20% and an adverse neurological result in up to 50% of survivors. A complicated series of interactions among the host immune response and oxidants seems to be responsible for meningitis associated brain dysfunctions. Na+,K+-ATPase is an essential enzyme responsible for generating and maintaining the membrane potential necessary for neural excitability, however, the Na+,K+-ATPase activity is altered in several illness;

Objective: The aim of this study is to evaluate the Na+,K+-ATPase activity in hippocampus and cortex of the rats submitted to pneumococcal meningitis.

Methods: Animals received 10 µl sterile saline as a placebo or an equivalent volume ofStreptococcus pneumoniaeto the concentration of 5 × 109cfu/ml and were killed at 24, 48, 72 and 96 h after meningitis induction. The brain structures, hippocampus and cortex, were immediately isolated on dry ice and stored at −80°C to analyse Na+,K+-ATPase activity.

Results: In the hippocampus, we verified the increase of Na+,K+-ATPase activity at 48, 72 and 96 h (p< 0.05) and in the cortex at 24 h (p< 0.05) after pneumococcal meningitis induction.

Conclusion: The Na+,K+-ATPase activity is under the control of a diversity of intracellular messengers that are able to modulate the function of the particular isozymes in a precise way. Furthermore, we verified that pneumococcal meningitis increased the Na+,K+-ATPase activity in hippocampus and cortex; this increase can be correlated with a compensatory mechanism in illness pathophysiology.
Molecular basis of maternal age‐related increase in oocyte aneuploidy
Authors: Kurahashi Hiroki , Tsutsumi Makiko , Nishiyama Sachie , Kogo Hiroshi , Inagaki Hidehito , Ohye Tamae
Published: November 2011

Aneuploidy is one of the most common and serious pregnancy complications in humans. Most conceptuses with autosomal aneuploidy die in utero, resulting in early pregnancy loss. However, some fetuses with aneuploidy survive to term but suffer from disorders associated with congenital anomalies and mental retardation, such as Down syndrome with trisomy 21. Three general characteristics of this condition are well acknowledged: (i) in most cases the extra chromosome is of maternal origin; (ii) most cases are derived from a malsegregation event in meiosis I; and (iii) the frequency of these errors increases with maternal age. The basis for the age‐dependent increase in meiosis I errors has been a long‐standing enigma. Many investigators have addressed the nature of this biological phenomenon through genomic analyses of extra chromosome 21 using polymorphic markers to determine the frequency or location of crossovers that should ensure faithful chromosome segregation. Cytogenetic analyses of in vitro unfertilized oocytes have also been performed. However, no definitive conclusions regarding meiosis I errors have yet been reached from such studies. Recent findings in conditional knock‐out mice for meiosis‐specific cohesin have shed further light on this issue. The present review focuses on the current understanding of age‐related aneuploidy and provides an overview of the mechanisms involved. We refer to recent data to illustrate some of the new paradigms that have arisen in this field.
Reducing the environmental footprint of wastewater screenings through anaerobic digestion with resource recovery
Authors: Cadavid‐Rodriguez Luz Stella , Horan Nigel
Published: November 2011

Screenings produced as the first stage of wastewater treatment and currently disposed of to landfill, are rich in volatile organic solids, nitrogen and phosphorus which could be recovered through anaerobic digestion. Biochemical methane potential (BMP) tests on screenings demonstrated a methane yield of 0.33 m3 methane/kg volatile solids (VS) and a VS destruction of 50%. Consequently, the effect of a range of hydraulic retention time (HRT) and organic loading rates (OLRs) was evaluated in lab‐scale continuously fed mesophilic digesters. The highest methane yield of 0.416 Nm3 methane/kg VS added was observed with an HRT of 15 days and an OLR of 2.5 kg VS/m3/day, when up to 65% of the VS were destroyed. If treated by anaerobic digestion, every dry tonne of screenings digested would divert 466 kg from landfill, save 4.6 tonne equivalent carbon dioxide (CO2 eq) and deliver 3.4 MWh of renewable energy.
The implications of nongenetic inheritance for evolution in changing environments
Authors: Bonduriansky Russell , Crean Angela J. , Day Troy
Published: November 2011

Nongenetic inheritance is a potentially important but poorly understood factor in population responses to rapid environmental change. Accumulating evidence indicates that nongenetic inheritance influences a diverse array of traits in all organisms and can allow for the transmission of environmentally induced phenotypic changes (‘acquired traits’), as well as spontaneously arising and highly mutable variants. We review models of adaptation to changing environments under the assumption of a broadened model of inheritance that incorporates nongenetic mechanisms of transmission, and survey relevant empirical examples. Theory suggests that nongenetic inheritance can increase the rate of both phenotypic and genetic change and, in some cases, alter the direction of change. Empirical evidence shows that a diversity of phenotypes – spanning a continuum from adaptive to pathological – can be transmitted nongenetically. The presence of nongenetic inheritance therefore complicates our understanding of evolutionary responses to environmental change. We outline a research program encompassing experimental studies that test for transgenerational effects of a range of environmental factors, followed by theoretical and empirical studies on the population‐level consequences of such effects.
Encouraging Debate on the Uniform Guidelines and the Disparate Impact Theory of Discrimination
Authors: McDaniel Michael A. , Kepes Sven , Banks George C.
Published: November 2011

This response summarizes commentaries on the M. A. McDaniel, S. Kepes, and G. C. Banks (2011) article, which argued that the Uniform Guidelines on Employee Selection Procedures are a detriment to the field of personnel selection. Several themes were present in the commentaries. No compelling arguments were presented to dispute the assertion that mean racial differences in job-related attributes will be with us for a long time. However, compelling arguments were made that the disparate impact theory of discrimination is a more central issue for personnel selection than the Uniform Guidelines. Similarly, arguments were presented that the assessment of adverse impact is problematic and that expert witness testimony needs improvement. Areas in need of further investigation were also identified. Finally, the role of the Society of Industrial and Organizational Psychology (SIOP) in guiding regulatory, legislative, and court actions was considered.
Effect of intraocular lens asphericity on posterior capsule opacification between two intraocular lenses with same acrylic material: a fellow‐eye study
Authors: Nanavaty Mayank A. , Spalton David J. , Gala Kavita B. , Dhital Anish , Boyce James
Published: November 2011

Purpose:  To evaluate intra‐individual differences in posterior capsule opacification (PCO) and visual performance between spherical AcrySof SN60AT and an aspheric AcrySof SN60WF intraocular lens (IOL) with a posterior aspheric surface, both of which are made of same hydrophobic acrylic material.

Setting:  Ophthalmology Department, St Thomas’ Hospital, London, UK.

Methods:  In this prospective randomized, fellow‐eye comparison, an aspheric IOL, which is 9% thinner in comparison with the spherical IOL, was randomized to the first eye of 47 patients and fellow‐eye surgery was performed within 3 weeks. Follow‐up was at 1, 3, 6, 12 and 24 months. Corrected logMAR visual acuity (CDVA) was measured at 100% and 9% contrast. After pupil dilation, digital retroillumination photographs were taken and the mean PCO percentage was calculated using poco software at each follow‐up visit.

Results:  At 1, 3, 6, 12 and 24 months, 47 (94 eyes), 44 (88 eyes), 42 (84 eyes) and 41 (82 eyes) patients were followed‐up respectively. Hundred per cent and 9% of LogMAR CDVA was not significantly different between the two IOLs (p = NS at all time‐points). Percentage area PCO scores (mean ± SD) at 1, 3, 6, 12 and 24 months with the spherical IOL was 5.82 ± 9.89, 7.76 ± 16.83, 7.21 ± 12.46, 9.29 ± 18.25 and 14.39 ± 25.42, respectively, and with an aspheric IOL was 8.91 ± 12.79, 5.97 ± 10.32, 5.15 ± 7.92, 7.68 ± 11.18 and 12.18 ± 20.10, respectively (p = NS at all time‐points).

Conclusions:  Posterior capsule opacification was not significantly different between the spheric and aspheric IOLs in this fellow‐eye, randomized comparison. Additional asphericity on the existing model of IOL does not influence PCO performance.
Karyomorphology of six taxa in Chrysanthemum sensu lato (Anthemideae) in Egypt and their genetic relationships by Giemsa C‐banding
Authors: ABD EL‐TWAB Magdy Hussein , MEKAWY Ahmad Mohammad M. , EL‐KATATNY Mohammad Saad
Published: November 2011

Abstract  Giemsa C‐banding was applied to the chromosome complements of six diploid species belonging to six genera in Chrysanthemum sensu lato (Anthemideae) distributed in Egypt. Four types of C‐banding distribution were observed in the taxa as follows: (i) negative C‐banding in Anacyclus monanthos (L.) Thell.; (ii) all bands in terminal regions in Achillea fragrantissima (Forssk.) Sch. Bip, which showed 32 bands on 18 chromosomes; (iii) all eight bands at centromeric regions on eight chromosomes in Matricaria recutita L.; and (iv) bands at terminal and centromeric regions in Brocchia cinerea Vis. (12 terminal and six centromeric bands on 12 chromosomes), Cotula barbata DC. (four terminal, six centromeric, and eight short arm bands on 16 chromosomes), and Glebionis coronaria (L.) Cass. ex Spach. (eight terminal on the short arms and four large bands in centromeric regions on 12 chromosomes).
Factors associated with basal insulin dose in Japanese children and young adult type 1 diabetics
Authors: Hashimoto Tomomi , Kawamura Tomoyuki , Kashihara Yoneo , Hirose Masakazu , Higashide Takashi , Tsuruhara Akitoshi , Fujimoto Hiroki , Noi Kaori , Shintaku Haruo
Published: November 2011

Aims/Introduction:  The daily basal insulin doses/body weight and the daily basal insulin doses/total daily insulin doses of Japanese type 1 diabetes mellitus patients are less than those of Western type 1 diabetes mellitus patients. It is known that Western meals are richer in fat than Japanese meals. We speculated that fat intake might be associated with basal insulin dose in type 1 diabetes mellitus patients.

Materials and Methods:  Forty‐one outpatients with type 1 diabetes mellitus (20 males, 21 females, mean age 15.9) were enrolled. Variables investigated included: gender, SDS‐BMI, HbA1c, duration of diabetes, therapy (MDI or CSII), insulin doses and meal contents. Meal contents were recorded for 3 days using a digital camera. Correlation and multiple regression analyses were performed for all subjects and each age group.

Results:  The mean daily basal insulin doses/total daily insulin doses was 0.35. In the multiple regression analysis among all subjects, when daily basal insulin doses/body weight was used as a dependent variable, fat energy ratio of the meal was obtained as an entered variable (P = 0.001). This tendency was particularly strong among the patients aged 14 or above (P < 0.001, standardized coefficient β = 0.683).

Conclusions:  In the type 1 diabetes patients who are aged 14 or above, an association between daily basal insulin doses/body weight and fat energy ratio of meal was suggested. This may explain the aforementioned expectation of increased fat intakes making higher basal insulin doses. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2011.00171.x, 2011)
Breaking the sticks: a hierarchical change‐point model for estimating ontogenetic shifts with stable isotope data
Authors: Authier Matthieu , Martin Céline , Ponchon Aurore , Steelandt Stephanie , Bentaleb Ilham , Guinet Christophe
Published: November 2011

1. Stable isotopes are increasingly used in ecology to investigate ontogenetic shifts in foraging habitat (via δ13C) and in trophic level (via δ15N). These shifts are in essence an individual‐level phenomenon, requiring repeated measures throughout the life of individuals, i.e. longitudinal data. Longitudinal data require in turn specifying an appropriate covariance structure. Here we present a hierarchical model to jointly investigate individual ontogenetic shifts in δ13C and δ15N values.

2. In a Bayesian framework, we used a Cholesky decomposition for estimating a moderately‐sized covariance matrix, thereby directly estimating correlations between parameters describing time‐series of isotopic measurements. We offer guidelines on how to select the covariance structure.

3. The approach is illustrated with a hierarchical change‐point (or broken stick) model applied to a data set collected on Southern Elephant Seals, Mirounga leonina. Ontogenetic shifts in foraging habitat, following a juvenile and variable stage, were detected and interpreted as fidelity to a foraging strategy; while ontogenetic shifts in trophic level were more likely the result of complete independence from maternal resources followed by a gradual increase in trophic level as seals aged.

4. Specifying both an appropriate covariance and mean structure enabled us to draw strong inferences on the ecology of an elusive marine predator, and has wide applicability for isotopic ecology provided repeated isotopic measurements are available.
A sensitive liquid chromatography coupled with mass spectrometry method for the intracellular and plasma quantification of raltegravir after solid-phase extraction
Authors: Mosnier-Thoumas Stéphanie , Djabarouti Sarah , Xuereb Fabien , Lazaro Estibaliz , Pellegrin Jean-Luc , Saux Marie-Claude , Breilh Dominique
Published: November 2011

Introduction

Liquid chromatography coupled with mass spectrometry for the quantification of raltegravir in human plasma and peripheral blood mononuclear cells has been developed.

Methods

Sample preparations were based on a fully automated solid-phase extraction process. Mass spectrometric data were acquired in a single-ion monitoring method. Raltegravir and quinoxaline, the internal standard, were well separated in a gradient mode over 15 min.

Key findings

Validation study exhibited excellent linearity, with good intra- and inter-day precision and accuracy.

Conclusions

The assay was successfully applied to the raltegravir quantification in HIV-infected patients.
Salvia miltiorrhiza and anisodamine appear to reduce the incidence of skin flap ischaemia and necrosis post mastectomy
Authors: Savović J
Published: November 2011

Chen J, Lv Q, Yu M, Zhang X, Gou J.

Randomized clinical trial of Chinese herbal medications to reduce wound complications after mastectomy for breast carcinoma.

Br J Surg 2010; 97: 1798–804.
Andrographis paniculata extract versus mesalazine for the treatment of active ulcerative colitis
Authors: Guo R
Published: November 2011

Tang T, Targan SR, Xu C, Byers VS, Sandborn WJ.

Randomized clinical trial: herbal extract HMPL‐004 in active ulcerative colitis – a double‐blind comparison with sustained release mesalazine.

Aliment Pharmacol Ther 2011; 33: 194–202.
Spinal manipulation for chronic back pain?
Authors: Ernst E
Published: November 2011

Rubinstein SM, van Middelkoop M, Assendelft WJ, de Boer MR, van Tulder MW.

Spinal manipulative therapy for chronic low‐back pain.

Cochrane Database Syst Rev 2011; 2: CD008112.
The prevalence of herbal medicine use among surgical patients in Trinidad
Authors: Merritt‐Charles Lorna
Published: November 2011

The aim of this study is to determine the prevalence of herbal medicine usage among surgical patients in three hospitals in Trinidad. The study population comprised 303 surgical outpatients randomly selected from the three hospitals. All patients were over 18 years of age. Eligible participants either had surgery within the previous year or were due for surgery within the following 6 months. Of the 303 subjects, 121 (40%) reported the use of herbal medicines. Twenty‐five percent of patients attending Hospital 1 used herbal medicines, compared with 41% at Hospital 2 and 55% at Hospital 3. The difference between the three hospitals was statistically significant (P=0.023). Allium sativum (garlic) was the most common herb used (74%), followed by Citrus sinensis (orange peel) tea (47%), Cymbopogon citratus (lemongrass) (39%), Aloe vera (aloe) (31%) and Panax ginseng (Asian ginseng) (26%). The prevalence of herbal medicine usage among interviewed patients in Trinidad is similar to the prevalence rate reported in the USA and Italy. The reported use of garlic was high, which is a concern as this herb may impact on bleeding in surgical patients. Herbal medicines may also influence heart rate, blood clotting and anaesthesia, which could put surgical patients at further risk. Due to the risk of potential complications, an accurate herbal medicine history should be obtained for all surgical patients.
Modulation of Kv3.4 channel N‐type inactivation by protein kinase C shapes the action potential in dorsal root ganglion neurons
Authors: Ritter David M. , Ho Cojen , O’Leary Michael E. , Covarrubias Manuel
Published: November 2011

Non‐technical summary  The orchestrated activity of an ensemble of voltage‐gated ion channels determines the initiation, shape and duration of the action potential in excitable cells. In primary pain‐sensing neurons, this ensemble includes a high voltage‐activated potassium channel. However, its molecular identity, function and modulation were unknown. Here, we show that the rapidly inactivating Kv3.4 channel underlying the high voltage‐activated potassium current is a major determinant of action potential repolarization. Furthermore, we found that physiological activation of protein kinase C dramatically slows Kv3.4 channel inactivation, which enhances the channel's ability to influence action potential repolarization. Based on these results and earlier work, we conclude that phosphorylation of the Kv3.4 channel inactivation gate is a mechanism by which pain‐sensing neurons shape action potential repolarization. This modulation will influence Ca2+‐dependent processes that play vital roles in nociception and might become deregulated in chronic pain.
Control of firing patterns through modulation of axon initial segment T‐type calcium channels
Authors: Bender Kevin J. , Uebele Victor N. , Renger John J. , Trussell Laurence O.
Published: November 2011

Non‐technical summary  Spontaneous bursting, in which neurons spontaneously fire clusters of action potentials, underlies a variety of neuronal functions, including breathing and sleep rhythms. The cellular mechanisms that underlie spontaneous burst generation are poorly understood. Here, we show that calcium‐permeable ion channels, recently shown to be localized to the site of action potential initiation in the initial segment of axons, are crucial for the generation of spontaneous bursts in auditory brainstem neurons. Block of calcium influx at this site was sufficient to convert spontaneous bursting neurons into neurons which fired in a regular pattern. Block could also be mediated by the neurotransmitter dopamine, which alters calcium channel activity through a kinase dependent mechanism. These results are the first to show that spontaneous firing mode can be controlled by neuromodulators acting on a specific cellular compartment, and highlight the importance of these calcium channels in the generation of spontaneous neuronal rhythm.
Diet‐induced adaptation of vagal afferent function
Authors: Kentish Stephen , Li Hui , Philp Lisa K. , O’Donnell Tracey A. , Isaacs Nicole J. , Young Richard L. , Wittert Gary A. , Blackshaw L. Ashley , Page Amanda J.
Published: November 2011

Non‐technical summary  Obesity is the result of a disruption in the maintenance of energy balance such that energy intake exceeds expenditure. Why this occurs is unknown. We show that after food deprivation or consumption of a high fat diet gastric vagal afferent responses to distension are reduced. In addition, the effect of the orexigenic peptide ghrelin is enhanced. Thus the satiety signal is reduced not only after food deprivation but also after a high fat diet. This reduction in satiety signalling may explain the increase in energy intake and disruption in maintenance of energy balance in obesity.
Index Method for Pumping Operation of Reversible Pump-Turbine
Authors: Yamabe M. , Yamaguchi Y.
Published: November 2011

The adaptability of the Winter-Kennedy index method [1] was examined, and consequently “Draft Tube Index Method” for Francis and diagonal flow pump-turbines under pumping operation were newly investigated experimentally. It is clarified that the Winter-Kennedy method is applicable to Francis pump-turbines, but not suitable to apply on diagonal flow pump-turbines with adjustable guidevanes, and that the draft tube index method, depending upon differential pressure between two pressure taps provided on the draft tube or on the air-pipe, indicates sufficient accuracy to apply on Francis and diagonal flow pump-turbines.
Experimental Study of the Effects of Orifice Plate Eccentricity on Flow Coefficients
Authors: Miller R. W. , Kneisel O.
Published: November 2011

An experimental program was undertaken to evaluate orifice flow coefficient variations with changes in plate concentricity. The tests were conducted on four Beta ratio orifice plates, ranging from 0.4 to 0.7, mounted in a special flange tap test fixture in a four-inch water line. The results are presented as the percent variation in flow coefficient, from the centered value, for a given eccentricity in an X, Y coordinate system in the plane of the orifice plate. The results indicate that the change in flow coefficient is a function of the magnitude and direction of the eccentricity and the Beta ratio. The coefficients were higher than the centered value independent of orifice center motion with an X, Y coordinate system. The relationship of these results to the concentricity specifications of existing codes and available literature is also presented.
Low-Cycle Fatigue Behavior Under Biaxial Strain Distribution
Authors: Mattavi J. L.
Published: November 2011

This paper presents a linear cumulative damage theory considering macroscopically both elastic and plastic straining to define behavior in the low-cycle fatigue region of the classic S-N curve. A combined strain mode was considered throughout the study with biaxiality effects accounted for through the von Mises theory. An experimental evaluation was conducted to determine the validity of the theory. The biaxial strain mode was provided by centrifugally loading 6-in-dia rotors. Experimentation on SAE 4340 steel alloy supported the damage theory and confirmed the existence of exponential relationships between equivalent elastic strains with cyclic life and equivalent plastic strains with life similar to those contained in the literature for uniaxially loaded specimens. A limited evaluation of an aluminum casting material, C 355-T61, also supported this exponential dependency.
Double-Notch Creep Rupture of 5 Cr-0.5 Mo Steels
Authors: Suezawa Yoshitada , Shinagawa Hideo
Published: November 2011

Following up their earlier work on unnotched and single-notched specimens of 5 Cr-0.5 Mo steel, the authors investigated the change in notch profile and dimensions, as well as the structural change of the notched part, mainly for the double-notched specimens of the same material during creep deformation up to rupture, paying special attention to an interaction of notches. The most interesting result obtained is as follows: Changes in notch profile and dimensions, as well as in structures, occurred more rapidly and markedly, and the rupture strength decreased, as the distance between notches decreased.
A Reaction-Rate Treatment of the Extrapolation Methods in Creep Testing
Authors: Grounes M.
Published: November 2011

Various phenomenological equations for the dependence of the time-to-rupture, etc., on temperature and stress have been related to a generalized equation based on chemical reaction-rate theory. In the derivation of these equations the assumption, which has been used and criticized in earlier work, that the time-to-rupture is inversely proportional to the creep rate and thus that the ductility is constant, is not needed.
Investigation of the Relaxation of Residual Stresses in Autofrettaged Cylinders
Authors: Dawson Victor C. D. , Jackson J. W.
Published: November 2011

Autofrettaged cylinders have been restricted in their use to relatively low temperatures because of the stress relieving effect of high temperatures. Thus, it was felt that high-temperature operation would alter the stress pattern to such an extent that the auto-frettage process would be of little benefit. This study was conducted to determine what the effects of time and temperature would be on the residual stresses. Small-size autofrettaged cylinders were subjected to temperatures varying from 400 to 850 F for times varying from 1 hr to 72 hr. The residual stresses were determined using a modification of the Sachs’ boring-out technique. The results indicated a stress relief in all the cylinders subjected to high temperatures. However, it was found that for a given temperature and time the bore tangential stress relaxes in a manner that can be predicted by means of creep data. This relation appears to have a limiting value related to the creep-resistant characteristics of the material.
Initial Development of Turbulent, Compressible Free Shear Layers
Authors: Hill W. G. , Page R. H.
Published: November 2011

The mixing zone between a two dimensional free stream and a fluid essentially at rest is studied experimentally and analytically. Turbulent shear layer velocity profiles were measured behind rearward facing steps and over cavities for equivalent free stream Mach numbers from 2.1 to 3.7, utilizing a wind tunnel wall boundary layer. Approximate methods are derived for calculating the shear layer change from an attached turbulent boundary layer to a fully developed free shear layer. A linearized equation of motion is used for the early stages of development, whereas the downstream stages are calculated by using a similarity profile. Both methods permit rapid calculations of the shear layer profile at any location along the mixing zone, without the necessity of determining the intermediate profiles. Comparison of the approximate methods with these experiments, and with experiments of other investigators, shows good agreement over the subsonic to supersonic Mach number range examined.
Low Density Nozzle Flow
Authors: Colwell G. T.
Published: November 2011

Experimental data are presented for the flow of argon in a converging nozzle in the continuum, slip, and free molecular regimes. The data are plotted in a number of ways so as to show clearly the characteristics of the flow. In addition, an empirical equation is offered with which one can estimate the flow at any pressure level.
The Stability of a Second Order Linear Periodic System
Authors: Davison E. J.
Published: November 2011

Necessary and sufficient conditions are obtained for the stability of the following second order linear system: x˙=θ(t)x,θ(t)=θt+∑i=1lTi and θ(t) =A1,0<t<T1=A2,T1<t<T1+T2⋮=Al,∑i=1l−1Ti<t<∑i=1lTi in terms of the eigenvalues and elements of the matrices Ai, i = 1, 2…l. The conditions become very simple for the case that l = 2. An example of a pendulum with a vibrating support is included.
Identification of Distributed Parameter Systems Using Finite Differences
Authors: Collins P. L. , Khatri H. C.
Published: November 2011

A method is presented to identify partial differential equations and associated boundary conditions of a distributed parameter system. The method is applicable to linear, nonlinear, and time-varying systems. The technique requires that the form of the differential equation and boundary conditions be known up to a set of constant parameters. Finite differences are used to approximate derivatives. Identification is carried out by using normal operating data. The accuracy of the identification depends upon the approximation errors and measurement noise. Methods for decreasing approximation errors are presented.
The Performance Characteristics of Geometrically Similar Bistable Amplifiers
Authors: Sarpkaya T.
Published: November 2011

The results of a comprehensive study of the comparative performance characteristics of geometrically similar vented and unvented bistable amplifiers, together with their actual dimensions, are presented. The Reynolds number in the tests ranged from 9,750 to 60,000, Mach number from 0.07 to 0.42, and the power jet velocity from 75 to 460 ft/sec. Each amplifier as conceived and designed was capable of giving a maximum of geometric flexibility which enabled a systematic evaluation of the shape and location of the splitter plate and Coanda-walls. It was found, within the range of Reynolds and Mach numbers tested, that certain gain characteristics and the range of operation of a given unvented amplifier overlap, within a narrow range of P0/Ps and Q0/Qs values, with the corresponding gain characteristics and the range of operation of the vented amplifier. It was also found that a convex-walled amplifier with proper geometry exhibits considerably better performance characteristics than are normally associated with such devices.
An Analytical Model for the Incompressible Flow in Short Vortex Chambers
Authors: Wormley D. N.
Published: November 2011

A momentum integral analysis is presented for the incompressible, steady, axisymmetric flow in a short vortex chamber of the type commonly used in vortex valves. The analysis is developed with the aid of flow visualization photographs and considers the interaction which occurs between the main vortex core flow and the viscous chamber end wall boundary layers. The radial pressure distributions predicted by the analysis compare favorably with measured end wall static pressure distributions.
The Organizing Principle of Complex Living Systems
Authors: Iberall A. S. , McCulloch W. S.
Published: November 2011

A scheme is outlined for a useful way to think about the complex biological organism, man. It is based on physiological findings that the regulating and control functions in the system make use of active processes, exhibiting oscillatory properties [1]. The resulting homeostatic regulation, which was the key concept proposed by Bernard, Sechenov, and Cannon for the living system [2], emerges from mediation of these oscillators. Because of its dynamic character, the scheme is renamed homeokinesis [3]. The concept may be extended to man’s behavioral complex. In outline, it touches on all the time or frequency domains in life—that is, of the many episodes in man.
Water-Hammer Attenuation With a Tapered Line
Authors: Tarantine F. J. , Rouleau W. T.
Published: November 2011

An investigation has been made of the pressure attenuation that can be obtained through the application of a rigid tapered section located immediately upstream of a quick-closing valve or other surge-generating device. The model taken was that of an inviscid liquid flowing through the rigid tapered tube terminated by either a very long uniform line or a finite-length line and reservoir. This paper presents an outline of a theoretical method for solving the given problem, along with some practical solutions. A description and the results of experimental work performed to substantiate the theory are also included.
Effects of Curvature on Laminar Boundary Layers in Sink-Type Flows
Authors: Gustafson W. A. , Pelech I.
Published: November 2011

The two-dimensional, incompressible laminar boundary layer on a strongly curved wall in a converging channel is investigated for the special case of potential velocity inversely proportional to the distance along the wall. Similarity solutions of the momentum equation are obtained by two different methods and the differences between the methods are discussed. The numerical results show that displacement and momentum thickness increase linearly with curvature while skin friction decreases linearly.
Straight Channel Diffuser Performance at High Inlet Mach Numbers
Authors: Runstadler P. W. , Dean R. C.
Published: November 2011

Measurements have been made of the pressure recovery of straight wall, single plane divergence diffusers with inlet Mach numbers between 0.2 and choking (0.2 ≤ Mt < 1.0). In contrast to the widely held assertion in the literature, there is no “critical” inlet subsonic Mach number above which pressure recovery decreases drastically. Two aspect ratios, AS = 0.25 and 1.0, have been studied for a range of length-to-throat-width ratios L/W1 and divergence angles 2θ around the regions of peak recovery. Diffuser performance maps are given showing pressure recovery Cp as a function of diffuser geometry for fixed values of throat Mach number Mt, throat blockage B, and aspect ratio AS. Significant changes in the location and magnitude of pressure recovery do occur with variations in Mt, B, and AS. The importance to the designer of a knowledge of how diffuser performance depends upon geometric and diffuser inlet parameters is discussed.
Pressure Transients in Hydraulic Pipelines
Authors: Thorley A. R. D.
Published: November 2011

Equations of motion for a cylindrical tube containing a fluid are developed from a consideration of the forces and moments in the tube wall. These equations are solved for boundary conditions representing the situation where the fluid is flowing steadily through a horizontal pipe and a valve at the downstream end is closed instantaneously. The solution gives theoretical results for the usual water-hammer wave but also predicts the existence of a precursor wave. Expressions are derived for the velocities of propagation of both transients and their associated pressure changes. A comprehensive series of experiments has been carried out. Some interesting and probably unique results were obtained, which demonstrate the behavior of both transients. Measurements of velocity and pressure change have been made. The effect of axial restraint on the pipe is demonstrated.
Effects of Nonuniform Inlet Velocity Profiles on Flow Regimes and Performance in Two-Dimensional Diffusers
Authors: Wolf S. , Johnston J. P.
Published: November 2011

An analytical and experimental study on the effects of large distortions of inlet velocity profiles on flow regimes and performance in diffusers is reported. Experiments are restricted to flow in straight, two-dimensional diffusers with turbulent boundary layers. Systematic data are obtained for two general types of inlet flows: (1) simple, uniform shear flows in the core, and (2) severely nonuniform shear flows of the wake, jet, and step-shear type. For uniform shear flows a first order prediction method based on inviscid rotational flow and the boundary layer blockage concept is developed and verified for diffusers operating in the unstalled flow regime. For nonuniform shear flows the inviscid rotational model is shown to predict performance trends better than the irrotational model; however, the inviscid rotational model is inadequate as a precise prediction method because no account is taken of mixing in the core region. Geometry and performance correlations for peak pressure recovery (at constant N/W1) are also established.
Prediction of Flow of a Melted Plastic Through a Screw Extruder
Authors: Kaiser H. , Smith C. W.
Published: November 2011

A theory is formulated for predicting the variation in average pressure and the rise in average temperature in molten plastic along the axis of a screw extruder. The mathematical model is for a wide, shallow channel of negligible curvature and includes both down and cross channel components of the shearing stress which are related to strain rates by a generalized Rabinowitsch constitutive equation for a non-Newtonian Liquid. Twenty experiments were performed in a commercial screw extruder in which pressures and temperature changes in the plastic were measured. Experimental correlation with theory is very good for pressure distribution along the screw axis and fair for temperature rises of at least 50 deg F.
Slip Flow in the Entrance of a Tube
Authors: Chen R. Y.
Published: November 2011

This Note is concerned with velocity and pressure distributions in the entrance of a right circular tube with slip at the wall for incompressible flow. The method used by Campbell and Slattery [1] for continuum flow is extended to slip flow. The result is then compared with existing work.
Stress Corrosion Testing of 7079-T6 Aluminum Alloy in Seawater Using Smooth and Precracked Specimens
Authors: Chu H. P. , Wacker G. A.
Published: November 2011

Stress corrosion cracking of a 7079-T6 aluminum alloy in seawater was investigated by bend tests of smooth and precracked specimens. It was found that there was a general agreement between results of the two methods. The susceptibility of this alloy to inter-granular cracking was shown to depend on its directional characteristics. The use of precracked specimens for stress corrosion testing is discussed.
Tubular Stress-Rupture Testing of Chromium-Molybdenum Steels With High-Pressure Hydrogen
Authors: Sticha E. A.
Published: November 2011

Exposure to hydrogen at 900 F and 1800 psi for 2900 hr does not weaken 2 1/4 Cr:1 Mo steel. At 1000 F, however, both 1 1/4 Cr: 1/2 Mo and 2 1/4 Cr:1 Mo steel suffer some loss of strength, the effect being greater in the former steel. Welded samples appear to have about the same strength as unwelded.
Environmentally Assisted Fatigue Crack Growth Rates in SAE 4340 Steel
Authors: Gallagher J. P. , Sinclair G. M.
Published: November 2011

Corrosion fatigue crack growth rates for SAE 4340 steel in distilled water environments were investigated utilizing fracture mechanics techniques. Crack growth rates, resulting from various forms of repeated loading, were compared to those induced by static load using small sample statistical theory. These comparisons indicate that corrosion fatigue crack growth may be either time or cycle dependent depending on the load profile, loading frequency, and temperature. Data are presented suggesting that whenever the maximum cyclic stress intensity in the fatigue cycle is below the static threshold stress intensity (KIscc), the environment no longer plays a major part in assisting the crack growth rate.
Progressive Waves on Swirling Cavity Flow in a Circular Pipe
Authors: Hashimoto H.
Published: November 2011

The behavior of progressive waves moving through a circular pipe containing a rotating flow of water with an axial cavity is studied both theoretically and experimentally. The theoretical solution is based on an empirical relation for the rotational velocity distribution in the water along a radius between the cavity and the pipe wall, where this relation is in the form of a quadratic function fitted to experimental data. The frequencies of the progressive waves are determined experimentally from observation of the wave motion on the surface of the axial cavity. Comparison with the frequencies predicted by the theoretical solution show a satisfactory agreement. The agreement is much poorer if the rotational velocity is simply assumed to be equivalent to that induced by a potential flow vortex along the axis of the pipe.
A Fluid-Jet Amplifier With Flat Saturation Characteristics
Authors: Griffin W. S.
Published: November 2011

A proportional fluid-jet amplifier has been developed which exhibits flat saturation characteristics and also has reasonable gains, differential output pressures, and noise levels. The amplifier’s output pressure did not drop below 68 percent of its maximum value for any differential control-port pressure in excess of that which caused maximum receiver output. A three-stage, gain block showed less than 3.5 percent decrease in differential output pressure for control signals as high as 200 times their maximum output value.
The Growth of Surface Microcracks in Fatigue
Authors: Francis P. H.
Published: November 2011

An analytical theory is proposed for describing the growth of a small surface “microcrack” under uniaxial fatigue loading. The theory is based upon dimensional analysis and uses the stress-intensity factor and crack extension force concepts of elastic fracture mechanics. Experimental measurements were made of the growth of surface micro-cracks, ranging from 0.0005–0.040 in. long, in polished specimens of 4340 steel. Good correlation was achieved in comparing the test results with the theoretical predictions. Finally, an approach is indicated for extending the analytical model to the prediction of fatigue failure.
The Notch-Bend Strength of Titanium, Aluminum, and Copper-Base Alloys in Heavy Sections
Authors: Chu Huai Pu
Published: November 2011

The notch-bend strength of four titanium, eight aluminum, and eight copper-base alloys was measured. Specimen sizes ranged from 0.4 to 4 in. in section thickness. All materials showed a geometrical size effect on notch strength. Only the high-strength aluminum alloys were found to be prone to brittle fracture. In general, 7Al-2Cb-1Ta titanium, 5456-H321 and 6061-T6 aluminum, and the copper alloys can be considered as notch-tough materials. The titanium alloys exhibited maximum notch toughness with 6–7 percent aluminum content. Determination of plane-strain fracture toughness (KIc) values for the aluminum alloys is briefly discussed.
Confined-Jet Amplifier
Authors: Mayer E. A.
Published: November 2011

The confined-jet amplifier is a new fluidic amplifier, consisting of a power nozzle and a receiver which are located on the same axis in an enclosure. The control input is the enclosure pressure, and the output is the receiver pressure. The confined-jet amplifier can operate efficiently from 40 to 1000 psia. The output pressure recovery exceeds 85 percent of the supply pressure; typical pressure gain is 6.5. The vortex valve serves as an efficient input control element to the confined-jet amplifier. The combination is demonstrated to have stable infinite pressure gain.
On Cumulative Collapse of Cavitation Cavities
Authors: Kozirev S. P.
Published: November 2011

Highly nonsymmetrical bubble collapses are viewed photographically, and it is noted that the collapses occur in such a fashion as to produce liquid jets. These are considered as similar to shaped charges used in explosives, and a model based on cumulative jet formation is postulated to explain the damaging power of such collapses. The damage from cavitation bubble collapse is examined and found to be similar to that from water jet impact.
The Rosette, Star, Tensile Fracture
Authors: Clough W. R. , Vennett R. M. , Hrubec R. J.
Published: November 2011

A type of tensile fracture topography encountered fairly often in certain temperature ranges with specimens from forgings, billets, rod, and bar of quenched and tempered steel, is the “star” or “rosette.” Having available several steels which had been shown to be capable of exhibiting the rosette, star, fracture, tensile testing was done to establish the temperature ranges for which this fracture configuration was applicable. Explanations of the fracture, and determinations of the fracture modes, were sought through experimentation involving metallography and the electron microscope, and by application of continuum mathematical plasticity-fracture theory.