bluuebunny/crossref_metadata_2025 huggingface dataset:
A mean stress correction model for tensile and compressive mean stress fatigue loadings
Authors: Ince A
Published: November 2016

A new mean stress fatigue model based on the distortional strain energy is proposed to account for the mean stress effects on fatigue life. The proposed model is compared with the Morrow and the Smith‐Watson‐Topper (SWT) mean stress correction models using a number of experimental data sets for one cast iron, two steels and two aluminium alloys under tensile and compressive mean stress loadings. It is found that both the proposed mean stress correction model and the SWT model yield similar results and provide very good correlation for positive mean stress data and moderate negative mean stress data. For high compressive mean stresses, the proposed model shows reasonably good correlations, while the SWT model fails to correlate the fatigue data. The Morrow model was found to give poor correlations for all fatigue data analysed by yielding conservative results for compressive mean stresses and non‐conservative results for tensile mean stresses.
Kempowski's War
Authors: Santiáñez Nil
Published: November 2016

This article reads Walter Kempowski's Das Echolot as an instance of war writing. By analyzing the connection between Kempowski's portrayal of war and the main formal devices and ethical dimensions of Das Echolot, this essay posits Kempowski's groundbreaking work as a response to the challenge to language and representation posed by the Second World War as it was fought on the Eastern Front—a battleground that saw the intertwining of absolute war and total war. Specifically, I attempt to demonstrate that Das Echolot is both a formal refraction of total war and an ethical reversal of absolute war. Kempowski's opus magnum formally internalizes the structure of total war in order to cancel out the deadly notion of the “other” implied in absolute war. Ultimately, this essay seeks to reveal the radicalism, originality, and historical importance of Kempowski's writing of war.
Ingo Schulze's Adam und Evelyn: “Zwischen dem Nicht‐mehr und dem Noch‐nicht‐dort”
Authors: Weintraut Edward J.
Published: November 2016

Ingo Schulze has been heralded in some circles as one of the most important authors in contemporary Germany. However, his most recent novel, Adam und Evelyn (), has received little attention among literary scholars. Schulze portrays the anxiety felt by many East Germans during the Peaceful Revolution of 1989 as they weighed the advantages and disadvantages of illegally leaving the GDR. To illuminate his story, he relies on the foundational myth of the Garden of Eden while referencing authors as diverse as Wolfram von Eschenbach and Stanislaw Lem. As is the case with his earlier works, Schulze does not draw conclusions or provide interpretations; he demands of his readers a high tolerance for ambiguity and understatement as well as an active engagement with the text. This article attempts to initiate a critical discussion of this novel by exploring the themes that lie at its heart: choice, paradise, and mortality.
Theory analysis of the Dental Hygiene Human Needs Conceptual Model
Authors: MacDonald L , Bowen DM
Published: November 2016

Purpose

Theories provide a structural knowing about concept relationships, practice intricacies, and intuitions and thus shape the distinct body of the profession. Capturing ways of knowing and being is essential to any professions’ practice, education and research. This process defines the phenomenon of the profession – its existence or experience. Theory evaluation is a systematic criterion‐based assessment of a specific theory. This study presents a theory analysis of the Dental Hygiene Human Needs Conceptual Model (DH HNCM).

Methods

Using the Walker and Avant Theory Analysis, a seven‐step process, the DH HNCM, was analysed and evaluated for its meaningfulness and contribution to dental hygiene. The steps include the following: (i) investigate the origins; (ii) examine relationships of the theory's concepts; (iii) assess the logic of the theory's structure; (iv) consider the usefulness to practice; (v) judge the generalizability; (vi) evaluate the parsimony; and (vii) appraise the testability of the theory.

Findings

Human needs theory in nursing and Maslow's Hierarchy of Need Theory prompted this theory's development. The DH HNCM depicts four concepts based on the paradigm concepts of the profession: client, health/oral health, environment and dental hygiene actions, and includes validated eleven human needs that evolved overtime to eight. It is logical, simplistic, allows scientific predictions and testing, and provides a unique lens for the dental hygiene practitioner. With this model, dental hygienists have entered practice, knowing they enable clients to meet their human needs.

Conclusion

For the DH HNCM, theory analysis affirmed that the model is reasonable and insightful and adds to the dental hygiene professions’ epistemology and ontology.
Multiobjective bed management considering emergency and elective patient flows
Authors: Landa Paolo , Sonnessa Michele , Tànfani Elena , Testi Angela
Published: November 2016

In recent years, hospitals have increasingly been faced with a growing proportion of their inpatient work coming from the fluctuating and unpredictable demand of emergency admissions. The opportunity to move emergency patients who have been selected for admission out of the emergency department (ED) is linked to the ability of the hospital network to actually admit them. The latter is, in turn, correlated to the availability of inpatient beds in the hospital wards, which are shared resources between elective and emergency patients. Due to the overcrowding of EDs and the growing concern regarding reducing the number of inpatient ward beds, it is thus becoming crucial to improve the bed capacity planning and the management of emergency and elective patient admissions. In this direction, greater coordination and communication among the different healthcare providers involved in the pathway flows is required, and the so‐called “bed management” function plays a key role. This study starts with collaboration with the local health government (LHG) of the Liguria region aimed at studying the hospital bed management function. A large quantity of data records have been collected during one year of activity to obtain information related to the flow of emergency and elective patient pathways. A medium‐sized hospital located in the city of Genova has been chosen as a case study, and a discrete event simulation model has been developed to reproduce the multiple patient flows involved in the system. Multiobjective optimization analysis has been performed to choose the best bed allocations considering both operational and tactical decisions characterized by various trade‐offs among alternative conflicting objectives. The model can be used to help decision makers find a representative set of Pareto‐optimal solutions and quantify trade‐offs when satisfying different objectives.
An improvement in DEA cross‐efficiency aggregation based on the Shannon entropy
Authors: Song Lianlian , Liu Fan
Published: November 2016

This paper improves a recently proposed Data Envelopment Analysis (DEA) cross‐efficiency aggregation method based on the Shannon entropy. The weights for determining cross‐efficiency are derived from minimizing the square distance of weighted cross‐efficiency and weighted CCR efficiency. Our calculation example indicates that this method may produce inappropriate weights, which is significantly inconsistent with a widely accepted viewpoint. A variance coefficient method based on the Shannon entropy is presented to overcome the drawbacks of the DEA cross‐efficiency aggregation method. In this study, comparisons of weights and cross‐efficiency scores are provided.
Adolescent Healthcare Brokering: Prevalence, Experience, Impact, and Opportunities
Authors: Banas Jennifer R. , Wallis Lisa C. , Ball James W. , Gershon Sarah
Published: November 2016

ABSTRACT

BACKGROUND

Limited health literacy disproportionately affects those with limited English proficiency (LEP). Parents with LEP might rely on their adolescent children to interpret health information. We call this adolescent healthcare brokering. This study uncovers the prevalence of brokering, kinds of tasks, emotional and academic impact, and desired support.

METHODS

We invited 165 students from health classes (in a community in which 29.8% are foreign‐born and 53.4% speak another language at home) to complete a survey. We used IBM SPSS to calculate descriptive statistics.

RESULTS

Of the 159 who received parental consent and assented, 54.1% (N = 86) assist with healthcare tasks. When brokering, 80.2% (N = 69) translate. Most common tasks were talking to a doctor, reading prescriptions, and searching on the Internet. Participants were most confident reading prescriptions and talking to a doctor and least confident finding healthcare services. Among brokers, 29.1% (N = 24) missed school; 33.7% did not complete homework. They most wanted to learn about filling out insurance forms and talking to doctors.

CONCLUSIONS

Despite assurances that children are not permitted to interpret, adolescents are acting as healthcare brokers. The impact can be academic and emotional. Findings indicate a need for further research and support for adolescents who want to learn about healthcare tasks.
School Context Matters: The Impacts of Concentrated Poverty and Racial Segregation on Childhood Obesity
Authors: Piontak Joy Rayanne , Schulman Michael D.
Published: November 2016

BACKGROUND

Schools are important sites for interventions to prevent childhood obesity. This study examines how variables measuring the socioeconomic and racial composition of schools and counties affect the likelihood of obesity among third to fifth grade children.

METHODS

Body mass index data were collected from third to fifth grade public school students by teachers from 317 urban and rural North Carolina schools in 38 counties. Multilevel models are used to examine county‐, school‐, and individual‐level effects.

RESULTS

Low concentrations of poverty at the school level are associated with lower odds of obesity. Schools in rural counties had significantly higher rates of obesity, net the other variables in the model. Students in minority‐segregated schools had higher rates of obesity than those in more racially diverse schools, but the effect was not statistically significant once school‐level poverty was controlled.

CONCLUSIONS

Place‐based inequalities are important determinants of health inequalities. The results of this study show that school‐level variables related to poverty are important for understanding and confronting childhood obesity.
Parity: An Intuitive Case
Authors: Chang Ruth
Published: November 2016

In other work I have argued that items can be on a par, where being on a par is a fourth, basic, sui generis value relation beyond the usual trichotomy of ‘better than’, ‘worse than’, and ‘equally good’. In this paper, I aim to marshal non‐technical, intuitive arguments for this view. First, I try to cast doubt on the leading source of intuitive resistance to parity, the conviction that if two items are comparable, one must be better than the other, worse than it, or they must be equally good. Second, I explain how parity can arise by appealing to an uncontroversial distinction between quantity and quality of value. I propose both sufficient conditions for parity and a nontechnical model of the notion. My overall aim is to bring into view a simple and intuitive picture of value – and more generally of normativity – in which parity plays a significant role.
COPD Assessment Test for measurement of health status in patients with idiopathic pulmonary fibrosis: A cross‐sectional study
Authors: Matsuda Toshiaki , Taniguchi Hiroyuki , Ando Masahiko , Kondoh Yasuhiro , Kimura Tomoki , Kataoka Kensuke , Sakamoto Koji , Suzuki Atsushi , Furukawa Taiki , Hasegawa Yoshinori
Published: November 2016

ABSTRACT

Background and objective

The COPD Assessment Test (CAT) has been reported to have potential utility for measuring health status of idiopathic pulmonary fibrosis (IPF). Although the CAT has been developed for the assessment of COPD patients, it has not been fully evaluated exclusively in IPF. This study was designed to evaluate the validity of the CAT in IPF.

Methods

The clinical data for 106 consecutive subjects with newly diagnosed IPF who completed pulmonary function tests, partial pressure of oxygen in arterial blood (PaO2
) at rest, 6‐min walk test (6MWT), CAT, St George's Respiratory Questionnaire (SGRQ), modified Medical Research Council (mMRC) dyspnoea grade and Hospital Anxiety and Depression Scale (HADS), were analysed. We assessed the validity of the CAT in comparison with the SGRQ.

Results

The present subjects showed mild to moderate restrictive impairment on spirometry. Mean CAT score and total SGRQ were 12.8 ± 8.0 and 30.8 ± 17.7, respectively. The concurrent validity of the CAT score in comparison with the SGRQ total score was significant (r = 0.72, P < 0.001). Internal consistency (Cronbach's α = 0.869) and repeatability over 3 months (intraclass correlation coefficient = 0.742) of the CAT were also significant. Single regression analysis showed that the CAT had significant construct validity. In multiple regression analysis, mMRC, PaO2
at rest, minimum SpO2
during 6MWT and anxiety of HADS were independent predictors for the CAT.

Conclusions

The CAT is a valid health status measurement in IPF patients. Multiple regression analysis showed that the CAT was significantly correlated with dyspnoea severity, oxygenation impairment and anxiety.
Two Phase Pressure Drop and Boiling Heat Transfer in Micro Pin Fin Channel
Authors: Jung Ki Moon , Lee Hee Joon
Published: November 2016

In this paper, boiling experiments were conducted to study two-phase pressure drop and the heat transfer coefficient in a staggered array micro pin fin channel of degassed water at a mass flux range of 9.3 to 46.6 kg/m2s and a heat flux of 0.5 to 0.9 W/cm2. Copper was used for the pin fin array microchannel heat sink, which was 31 mm in width and 82 mm in length. Micro pin fins, of 400 μm in diameter and 700 μm in height, were manufactured using a micro milling machine on the channel block. The distance between two pin fin surfaces is 300 μm. A thin film heater, which supplies a maximum constant heat flux of 1.55 W/cm2, was attached underneath the heat sink. From the experimental results, at a vapor quality of up to 0.04, the boiling heat transfer coefficient decreased as the quality increased. Results show that the heat transfer coefficient is dependent on the mass flux. The data also showed that the pressure drop increased with increasing mass flux. The data obtained in this study were compared to the existing correlations of boiling pressure drop and heat transfer coefficients. Results showed that the correlation with boiling pressure drop of Qu and Siu-Ho[22] yielded a prediction of 21.3% average error Additionally, as a result of comparison with the four existing correlations of boiling heat transfer coefficient, all correlations had a lower prediction for the heat transfer coefficients obtained in this study. Through visualization, it was found that the bubbles generated between the fins began to grow and moved downstream. We observed a stationary vapor pocket in which bubbles did not flow.
Adsorption-Controlled Thermal Diode: Nonequilibrium Molecular Dynamics Simulation
Authors: Avanessian Tadeh , Hwang Gisuk
Published: November 2016

A thermal diode is a system controlling the heat transfer preferentially in one direction. This serves as a basic building block to design advanced thermal management systems in energy saving applications and to provide implications to design new application such as thermal computers. The development of the thermal diode has been of great interest as electrical diodes have similarly made significant impacts on modern industries. Numerous studies have demonstrated thermal diode mechanisms using non-linear heat transfer mechanisms, but the main challenges in current systems are poor steady-state performance, slow transient response, and/or extremely difficult manufacturing for the viable solutions. In this study, an adsorption-based thermal diode is examined for a fast and efficient thermal diode mechanism as a completely new class, using a gas-filled, heterogeneous nanogap with asymmetric surface interactions in Knudsen regime. Ar gas atoms confined in Pt-based solid surfaces are selected to predict the degree of rectification, R ∼ 10, using non-equilibrium molecular dynamics simulation with the nanogap size of Lz = 20 nm and ΔT = 20 K for various average plate temperatures, 80 < T < 130 K. Different surface energies for the thermal diode is studied and a maximum degree of rectification, Rmax ∼ 10, is found at T = 80 K which results from the significant adsorption-controlled thermal accommodation coefficient (TAC). The obtained results provide insights into the design of advanced thermal management systems including thermal switches and thermal computing systems.
High Heat Flux Boiling Heat Transfer for Laser Diode Arrays
Authors: Bandhauer Todd M. , Bevis Taylor A.
Published: November 2016

The principle limit for achieving higher brightness of laser diode arrays is thermal management. State of the art laser diodes generate heat at fluxes in excess of 1 kW cm−2 on a plane parallel to the light emitting edge. As the laser diode bars are packed closer together, it becomes increasingly difficult to remove large amounts of heat in the diminishing space between neighboring diode bars. Thermal management of these diode arrays using conduction and natural convection is practically impossible, and, therefore, some form of forced convective cooling must be utilized. Cooling large arrays of laser diodes using single-phase convection heat transfer has been investigated for more than two decades by multiple investigators. Unfortunately, either large fluid temperature increases or very high flow velocities must be utilized to reject heat to a single phase fluid, and the practical threshold for single phase convective cooling of laser diodes appears to have been reached. In contrast, liquid-vapor phase change heat transport can occur with a negligible increase in temperature and, due to a high enthalpy of vaporization, at comparatively low mass flow rates. However, there have been no prior investigations at the conditions required for high brightness edge emitting laser diode arrays: >1 kW cm−2 and >10 kW cm−3.

In the current investigation, flow boiling heat transfer at heat fluxes up to 1.1 kW cm−2 was studied in a microchannel heat sink with plurality of very small channels (45 × 200 microns) using R134a as the phase change fluid. The high aspect ratio channels (4.4:1) were manufactured using MEMS fabrication techniques, which yielded a large heat transfer surface area to volume ratio in the vicinity of the laser diode. To characterize the heat transfer performance, a test facility was constructed that enabled testing over a range of fluid saturation temperatures (15°C to 25°C). Due to the very small geometric features, significant heat spreading was observed, necessitating numerical methods to determine the average heat transfer coefficient from test data. This technique is crucial to accurately calculate the heat transfer coefficients for the current investigation, and it is shown that the analytical approach used by many previous investigations requires assumptions that are inadequate for the very small dimensions and heat fluxes observed in the present study.

During the tests, the calculated outlet vapor quality exceeded 0.6 and the base heat flux reached a maximum of 1.1 kW cm−2. The resulting experimental heat transfer coefficients are found to be as large a 58.1 kW m−2 K−1 with an average uncertainty of ±11.1%, which includes uncertainty from all measured and calculated values, required assumptions, and geometric discretization error from meshing.
Modeling of Evaporation Phenomenon Considering Liquid and Vapor Phase Conduction Effects: Stefan Problems
Authors: Perez-Raya Isaac , Kandlikar Satish G.
Published: November 2016

In developing numerical code for interfacial evaporation problems, 1st Stefan problem is generally used for validation. In this paper, both 1st and 2nd Stefan problems are used for validating a numerical code that utilizes volume of fluid method and is based on ANSYS-Fluent along with user defined functions (UDFs) to account for the mass and energy transfer at the interface. The 2nd Stefan problem incorporates heat transfer in both phases and provides a more realistic representation of an evaporating interface. Emphasis is put on the vapor-liquid heat transfer, which takes into account the sensible heat transfer in the liquid phase where liquid conduction effects are important. The mass transfer model takes into account the temperature gradients in both phases at the interface. Analytical solutions for the two Stefan problems are reported and used for validation purposes. Results show that the interface displacement and temperature distributions are simulated accurately. The current approach utilizes the robust platform of ANSYS-Fluent while allowing an accurate representation of the phase change processes at the interface.
Modular Concept of a Smart Scale Helically Coiled Tubular Reactor for Continuous Operation of Multiphase Reaction Systems
Authors: Kurt Safa Kutup , Akhtar Mohd , Nigam Krishna Deo Prasad , Kockmann Norbert
Published: November 2016

Process intensification (PI) via microstructured devices has often been applied by research and development (R&D) and industry for a decade, as they offer a large specific surface area that enhances the mass and the heat transfer. Helically coiled tubular reactors (HCTR) in micro-scale can further increase the performance in terms of transport phenomena, as the secondary flow (Dean vortices) enhances the radial mixing along the tube. Therefore, a narrow residence time distribution (RTD) that is required for the operation of complex chemical reaction systems can be achieved for the long residence times (RTs) at laminar flow regimes In this study, the continuous precipitation of calcium carbonate (CaCO3) was investigated by using a smart scale HCTR, i.e. modular coiled flow inverter (CFI) made of polyvinyl chloride (PVC) tubes (di = 3.2 mm). Modular CFI consists of 90° bends connecting the helical coils in order to enhance the radial mixing further. For precipitation process calcium hydroxide (Ca(OH)2) solution and gaseous CO2/synthetic air mixture were contacted prior to the reactor inlet via a Y-mixer. Slug flow profile was maintained and CaCO3 was precipitated along the reactor tube. To avoid further reaction of CaCO3 with water that is saturated with CO2 (pH ≲ 8.6), which promotes the consecutive parallel reaction forming soluble calcium bicarbonate (Ca(HCO3)2), the RT of the reactor was easily varied by changing the tube length of the modular CFI. Precipitated CaCO3 particles with a conversion of ca. 90% were separated from the suspension by vacuum filtration. Influence of volumetric flow ratio of the gases (R = V̇CO2/V̇air) and the RT were investigated on the precipitation process at constant flow rates. A comparison is presented between a batch reactor and a modular CFI. Results showed that narrower particle size distribution (PSD) with median particle diameters (d50,2) around 28 μm and more uniform morphology can be achieved by using a CFI for the continuous production of the powders.
Heat Transfer Characteristics of Downward Supercritical Kerosene Flow in Minitubes
Authors: Lin Jinpin , Zhang Jingzhi , Sokolova Ekaterina , Li Wei
Published: November 2016

The heat transfer characteristics of supercritical China RP-3 aviation kerosene flowing downward in a vertical circular tube are numerically investigated. A ten-species surrogate model is used to calculate the thermophysical properties of kerosene and the Re-Normalization Group (RNG) k-ε model with the enhanced wall treatment is adopted to simulate the turbulent flow. The effects of diameter, wall heat flux, and pressure on temperature and heat transfer coefficient are studied. The numerical results show three types of heat transfer deterioration exist along the flow direction. The first deterioration at the tube inlet region is caused by the development of the thermal boundary layer, which exist whatever the operation condition is. The second and third kind of deterioration take place when the inner wall temperature or the bulk fuel temperature approaches the pseudo-critical temperature under a pressure close to the critical value. The heat transfer coefficients increase with decreasing diameter and increasing pressure. The increase of inlet pressure can effectively eliminate the deteriorations because the thermophysical properties change less near the critical point at higher pressure. The decrease of wall heat flux will delay the onsets of the second and third kind of deterioration. The numerical heat transfer coefficient fit well with the empirical correlations.
Dipole-Dipole Interaction Between Particle Complexes in a Magnetophoretic Bioseparation Chip
Authors: Alam Manjurul , Darabi Jeff
Published: November 2016

Particle-particle interaction is an important phenomenon in the analysis of particle transport in a microfluidic device. This paper presents a computational study to predict the interaction force between particle complexes in a magnetophoretic bio-separation chip. Magnetic flux gradients are simulated in OpenFOAM CFD software and imported to Matlab to obtain the particle trajectories. The interaction force is approximated using a dipole based model and implemented to track the particle motion in a microfluidic device in the presence of an applied magnetic field. The analysis of particle trajectories is performed for cases where the applied magnetic field is parallel or perpendicular to the inter-particle distance of the particle complexes by solving a system of coupled ordinary differential equations.
On the Impact of Liquid Drops on Immiscible Liquids
Authors: Castillo-Orozco Eduardo , Davanlou Ashkan , Choudhury Pretam K. , Kumar Ranganathan
Published: November 2016

The release of liquid hydrocarbons into the water is one of the environmental issues that have attracted more attention after deepwater horizon oil spill in Gulf of Mexico. The understanding of the interaction between liquid droplets impacting on an immiscible fluid is important for cleaning up oil spills as well as the demulsification process. Here we study the impact of low-viscosity liquid drops on high-viscosity liquid pools, e.g. water and ethanol droplets on a silicone oil 10cSt bath. We use an ultrafast camera and image processing to provide a detailed description of the impact phenomenon. Our observations suggest that viscosity and density ratio of the two media play a major role in the post-impact behavior. When the droplet density is larger than that of the pool, additional cavity is generated inside the pool. However, if the density of the droplet is lower than the pool, droplet momentary penetration may be facilitated by high impact velocities. In crown splash regime, the pool properties as well as drop properties play an important role. In addition, the appearance of the central jet is highly affected by the properties of the impacting droplet. In general, the size of generated daughter droplets as well as the thickness of the jet is reduced compared to the impact of droplets with the pool of an identical fluid.
Heat Transfer Characteristics of Supercritical Aviation Kerosene at Different Tube Diameters
Authors: Hong Xiao-qiang , Huang Dan , Li Wei , Zhu Hua
Published: November 2016

Supercritical fluids are widely used in aeronautic, astronautic and nuclear engineering. Active cooling is necessary for scramjet engines to survive the extreme heat generated in hypersonic flight. Regenerative cooling system, where engine fuel works as coolants and travels through the cooling tubes along the chamber wall, carrying away heat from the wall via heat convection and endothermic chemical reactions, is developed as an effective thermal management technique. In this paper, experimental results of convective heat transfer performances of aviation kerosene at supercritical pressures were presented. Stainless steel circular tubes having inner diameters of 1and 1.8 mm were investigated for pressures ranging from 3 to 4 MPa, mass flow rates from 1.87 to 2.41 g/s and heat fluxes from 285 to 365 kW/m2. It was found that the heat transfer coefficient increases with mass flow rate at the former part of the tube. However, as the Reynolds increases significantly at the latter part of the tube at relatively low mass flow rate, the heat transfer coefficient increases dramatically at the latter part of the tube at relatively low mass flow rate. The effect of heat flux on heat transfer is complicated, while the effect of pressure on heat transfer is insignificant. The experimental results also indicated that the heat transfer coefficient decreases with the reduction in tube diameter. The heat transfer behaviors in relation to changes in tube sizes might be caused by the buoyancy effect.
On the Heat Transfer Characteristics of a Single Bubble Growth and Departure During Pool Boiling
Authors: Mobli Mostafa , Li Chen
Published: November 2016

In the present study, bubble growth and departure characteristics during saturated pool boiling were investigated numerically, and a comprehensive model was proposed and developed to study the heat transfer during growth and departure of a bubble as well as bubble growth rate and departure time. Two-phase characteristics of the boiling phenomena can be captured by well-known Volume of Fluid (VOF) method. However, the VOF method is susceptible to parasitic currents because of approximate interface curvature estimations. Thus, sharp surface formula (SSF) method was employed to effectively eliminate the presence of the parasitic currents. VOF method is a volume capturing method and hence, may be subject to interface diffusion, due to the fact that interface is smeared through some number of computational cells. Interface compression scheme is applied to prevent the plausible interface diffusion of the VOF method. To avoid unrealistic temperature profiles at the solid-liquid surface, a conjugate heat transfer model was used to calculate the heat flux going into the liquid region from the heater through the solution of conduction equation in solids. Phase change at the interface was incorporated based on Hardt and Wondra’s model in which source terms are derived from a physical relationship for the evaporation mass flux. Furthermore, effects of micro region heat transfer on the departure time of the bubble was investigated. Micro region heat transfer was included in the model by solving a temporal evolution equation and incorporating the resulting heat flux in the tri-phase contact line. In this study, OpenFOAM package was used to investigate the characteristics of the bubble growth and departure as well as the wall heat flux. The model was benchmarked by comparing the simulation results to available experimental and numerical literatures, as well as analytical solutions.
High-resolution, high-aspect-ratio iridium–nickel composite nanoimprint molds
Authors: Lee Chang-Sheng , Lee Yeong-Yuh , Chong Karen S. L. , Wang Li , Dais Christian , Clube Francis , Solak Harun H. , Mohacsi Istvan , David Christian , Bischofberger Roger
Published: November 2016

Nanoimprint molds are traditionally made from silicon. Silicon molds suffer from distinct disadvantages as they are brittle, prone to damage, scratch easily, and can only be used in a planar format. This has limited their use in higher throughput systems where flexible molds are required such as in roll-to-roll and roll-to-plate systems. Nickel (Ni) molds, which are now de-rigueur in both batch and roller nanoimprint processes, can be used to address these problems, but fabrication and durability issues limit their availability and effectiveness in production. In this report, the authors introduce a fabrication route that has the potential to overcome the fabrication, quality, and wear problems of Ni molds. The new process relies on atomic layer deposition to form a smooth and high-aspect ratio patterned layer of iridium (Ir) on a Ni substrate. A large area nanohole array mold was fabricated using displacement Talbot lithography to demonstrate this process. The authors show the use of such composite molds via a batch thermal imprinting process to fabricate 70 nm hole arrays onto polycarbonate templates with a ±10% tolerance in diameter between the polycarbonate and the composite mold, and less than 1% of defects.
Stress and alcohol abuse
Authors: Ferrarelli Leslie K.
Published: November 2016

Glucocorticoid signaling increases alcohol use by deactivating the K
+
, Cl
–
transporter KCC2, which increases inhibitory input to dopaminergic neurons.
Paper of note in
Science Translational Medicine
Authors: Ferrarelli Leslie K.
Published: November 2016

This week’s article shows how defining the functional effects of genetic variants in the kinase TYK2 revealed a way to treat autoimmune disease.
Lipoic acid metabolism in Escherichia coli: the lplA and lipB genes define redundant pathways for ligation of lipoyl groups to apoprotein
Authors: Morris T W , Reed K E , Cronan J E
Published: November 2016

Lipoic acid is a covalently bound disulfide-containing cofactor required for function of the pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase, and glycine cleavage enzyme complexes of Escherichia coli. Recently we described the isolation of the lplA locus, the first gene known to encode a lipoyl-protein ligase for the attachment of lipoyl groups to lipoate-dependent apoenzymes (T. W. Morris, K. E. Reed, and J. E. Cronan, Jr., J. Biol. Chem. 269:16091-16100, 1994). Here, we report an unexpected redundancy between the functions of lplA and lipB, a gene previously identified as a putative lipoate biosynthetic locus. First, analysis of lplA null mutants revealed the existence of a second lipoyl ligase enzyme. We found that lplA null mutants displayed no growth defects unless combined with lipA (lipoate synthesis) or lipB mutations and that overexpression of wild-type LplA suppressed lipB null mutations. Assays of growth, transport, lipoyl-protein content, and apoprotein modification demonstrated that lplA encoded a ligase for the incorporation of exogenously supplied lipoate, whereas lipB was required for function of the second lipoyl ligase, which utilizes lipoyl groups generated via endogenous (lipA-mediated) biosynthesis. The lipB-dependent ligase was further shown to cause the accumulation of aberrantly modified octanoyl-proteins in lipoate-deficient cells. Lipoate uptake assays of strains that overproduced lipoate-accepting apoproteins also demonstrated coupling between transport and the subsequent ligation of lipoate to apoprotein by the LplA enzyme. Although mutations in two genes (fadD and fadL) involved in fatty acid failed to affect lipoate utilization, disruption of the smp gene severely decreased lipoate utilization. DNA sequencing of the previously identified slr1 selenolipoate resistance mutation (K. E. Reed, T. W. Morris, and J. E. Cronan, Jr., Proc. Natl. Acad. Sci. USA 91:3720-3724, 1994) showed this mutation (now called lplA1) to be a G76S substitution in the LplA ligase. When compared with the wild-type allele, the cloned lplA1 allele conferred a threefold increase in the ability to discriminate against the selenium-containing analog. These results support a two-pathway/two-ligase model of lipoate metabolism in E. coli.
An epitope of elongation factor Tu is widely distributed within the bacterial and archaeal domains
Authors: Weber S , Lottspeich F , Köhl J
Published: November 2016

A monoclonal antibody (MAb), MAb 900, which detects a 43-kDa protein present on Escherichia coli was found. Subsequently, more than 90 organisms, belonging to either the bacterial, archaeal, or eucaryal domain, were tested for reactivity to this MAb. Of the bacterial and archaeal domains, almost all species proved to be positive, whereas all organisms from the eucaryal domain gave negative results. The 43-kDa protein was purified by affinity chromatography and subsequently analyzed by microsequencing methods. Two peptide sequences which showed a high degree of homology (> 99%) to the prokaryotic elongation factor Tu (EF-Tu) were obtained. Western blot (immunoblot) analysis using both purified EF-Tu and EF-Tu domains confirmed that the unknown protein was EF-Tu. The panbacterial distribution of EF-Tu, which is present in large amounts in every prokaryotic cell, renders this protein a good candidate for a diagnostic approach. In consequence, we have used the anti-EF-Tu MAb 900 to design both a dot blot assay and an enzyme-linked immunosorbent assay. From either blood culture, urine, or gall-bladder fluid, bacterial contamination could be detected. The sensitivity of these tests is currently 10(4) bacteria per ml.
The Bacillus subtilis rsbU gene product is necessary for RsbX-dependent regulation of sigma B
Authors: Voelker U , Dufour A , Haldenwang W G
Published: November 2016

sigma B is a secondary sigma factor of Bacillus subtilis. sigma B-dependent transcription is induced when B. subtilis enters the stationary phase of growth or is exposed to any of a number of different environmental stresses. Three genes (rsbV, rsbW, and rsbX), which are cotranscribed with the sigma B structural gene (sigB), encode regulators of sigma B-dependent gene expression. RsbW and RsbV have been shown to control sigma B activity, functioning as an inhibitory sigma B binding protein and its antagonist, respectively. Using the SPAC promoter (PSPAC) to control the expression of the sigB operon, a ctc::lacZ reporter system to monitor sigma B activity, and monoclonal antibodies to determine the levels of sigB operon products, we have now obtained evidence that RsbX is an indirect regulator of sigma B activity. Genetic data and in vivo measurements argue that RsbX negatively regulates an extension of the RsbV-RsbW pathway that requires the product of an additional regulatory gene (rsbU) which lies immediately upstream of the sigB operon. The results are consistent with RsbU, or a process dependent on RsbU, being able to facilitate the RsbV-dependent release of sigma B from RsbW but normally prevented from doing this by RsbX.
In vivo restriction by LlaI is encoded by three genes, arranged in an operon with llaIM, on the conjugative Lactococcus plasmid pTR2030
Authors: O'Sullivan D J , Zagula K , Klaenhammer T R
Published: November 2016

The LlaI restriction and modification (R/M) system is encoded on pTR2030, a 46.2-kb conjugative plasmid from Lactococcus lactis. The llaI methylase gene, sequenced previously, encodes a functional type IIS methylase and is located approximately 5 kb upstream from the abiA gene, encoding abortive phage resistance. In this study, the sequence of the region between llaIM and abiA was determined and revealed four consecutive open reading frames (ORFs). Northern (RNA) analysis showed that the four ORFs were part of a 7-kb operon with llaIM and the downstream abiA gene on a separate transcriptional unit. The deduced protein sequence of ORF2 revealed a P-loop consensus motif for ATP/GTP-binding sites and a three-part consensus motif for GTP-binding proteins. Data bank searches with the deduced protein sequences for all four ORFs revealed no homology except for ORF2 with MerB, in three regions that coincided with the GTP-binding motifs in both proteins. To phenotypically analyze the llaI operon, a 9.0-kb fragment was cloned into a high-copy-number lactococcal shuttle vector, pTRKH2. The resulting construct, pTRK370, exhibited a significantly higher level of in vivo restriction and modification in L. lactis NCK203 than the low-copy-number parental plasmid, pTR2030. A combination of deletion constructions and frameshift mutations indicated that the first three ORFs were involved in LlaI restriction, and they were therefore designated llaI.1, llaI.2, and llaI.3. Mutating llaI.1 completely abolished restriction, while disrupting llaI.2 or llaI.3 allowed an inefficient restriction of phage DNA to occur, manifested primarily by a variable plaque phenotype. ORF4 had no discernible effect on in vivo restriction. A frameshift mutation in llaIM proved lethal to L. lactis NCK203, implying that the restriction component was active without the modification subunit. These results suggested that the LlaI R/M system is unlike any other R/M system studied to date and has diverged from the type IIS class of restriction enzymes by acquiring some characteristics reminiscent of type I enzymes.
Transcriptional analysis of pqqD and study of the regulation of pyrroloquinoline quinone biosynthesis in Methylobacterium extorquens AM1
Authors: Ramamoorthi R , Lidstrom M E
Published: November 2016

Methanol dehydrogenase, the enzyme that oxidizes methanol to formaldehyde in gram-negative methylotrophs, contains the prosthetic group pyrroloquinoline quinone (PQQ). To begin to analyze how the synthesis of PQQ is coordinated with the production of other methanol dehydrogenase components, the transcription of one of the key PQQ synthesis genes has been studied. This gene (pqqD) encodes a 29-amino-acid peptide that is thought to be the precursor for PQQ biosynthesis. A unique transcription start site was mapped to a guanidine nucleotide 95 bp upstream of the pqqD initiator codon. RNA blot analysis identified two transcripts, a major one of 240 bases encoding pqqD and a minor one of 1,300 bases encoding pqqD and the gene immediately downstream, pqqG. Both transcripts are present at similar levels in cells grown on methanol and on succinate, but the levels of PQQ are about fivefold higher in cells grown on methanol than in cells grown on succinate. These results suggest that PQQ production is regulated at a level different from the transcription of pqqD. The genes mxbM, mxbD, mxcQ, mxcE, and mxaB are required for transcription of the genes encoding the methanol dehydrogenase subunits and were assessed for their role in PQQ production. PQQ levels were measured in mutants defective in each of these regulatory genes and compared with levels of pqqD transcription, measured with a transcriptional fusion between the pqqD promoter and xylE. The results showed that only a subset of these regulatory genes (mxbM, mxbD, and mxaB) is required for transcription of pqqD, and only mxbM and mxbD mutants affected the final levels of PQQ significantly.
Purification and characterization of 6-chlorohydroxyquinol 1,2-dioxygenase from Streptomyces rochei 303: comparison with an analogous enzyme from Azotobacter sp. strain GP1
Authors: Zaborina O , Latus M , Eberspächer J , Golovleva L A , Lingens F
Published: November 2016

The enzyme which cleaves the benzene ring of 6-chlorohydroxyquinol was purified to apparent homogeneity from an extract of 2,4,6-trichlorophenol-grown cells of Streptomyces rochei 303. Like the analogous enzyme from Azotobacter sp. strain GP1, it exhibited a highly restricted substrate specificity and was able to cleave only 6-chlorohydroxyquinol and hydroxyquinol and not catechol, chlorinated catechols, or pyrogallol. No extradiol-cleaving activity was observed. In contrast to 6-chlorohydroxyquinol 1,2-dioxygenase from Azotobacter sp. strain GP1, the S. rochei enzyme had a distinct preference for 6-chlorohydroxyquinol over hydroxyquinol (kcat/Km = 1.2 and 0.57 s-1.microM-1, respectively). The enzyme from S. rochei appears to be a dimer of two identical 31-kDa subunits. It is a colored protein and was found to contain 1 mol of iron per mol of enzyme. The NH2-terminal amino acid sequences of 6-chlorohydroxyquinol 1,2-dioxygenase from S. rochei 303 and from Azotobacter sp. strain GP1 showed a high degree of similarity.
hlyM, a transcriptional silencer downstream of the promoter in the hly operon of Escherichia coli
Authors: Jubete Y , Zabala J C , Juárez A , de la Cruz F
Published: November 2016

Transcription of the hly operon of transmissible plasmids in Escherichia coli is subject to a tight regulation which also involves various chromosomal genes, such as hha. We have identified a 200-bp region within the hlyC gene, designated hlyM, which modulates hemolysin expression. The deletion of hlyM increased the activity of hly::galK fusion 20-fold. hlyM does not contain any internal promoter, nor is it capable of acting in trans. Our data suggest that the chromosomal Hha protein interacts with hlyM in order to silence the hly promoter. In addition, hlyR, a positive activator of hemolysin expression, seems to suppress the modulatory effect dictated by the Hha protein on the hlyM region.
Specific binding of the NikA protein to one arm of 17-base-pair inverted repeat sequences within the oriT region of plasmid R64
Authors: Furuya N , Komano T
Published: November 2016

Products of the nikA and nikB genes of plasmid R64 have been shown to form a relaxation complex with R64 oriT DNA and to function together as an oriT-specific nickase. We purified the protein product of the nikA gene. The purified NikA protein bound specifically to the oriT region of R64 DNA. Gel retardation assays and DNase I footprinting analyses indicated that the NikA protein bound only to the right arm of 17-bp inverted repeat sequences; the right arm differed from the left arm by a single nucleotide. The binding site is proximal to the nick site and within the 44-bp oriT core sequence. Binding of the NikA protein induced DNA bending within the R64 oriT sequence.
Identification of mycobacterium tuberculosis DNA sequences encoding exported proteins by using phoA gene fusions
Authors: Lim E M , Rauzier J , Timm J , Torrea G , Murray A , Gicquel B , Portnoi D
Published: November 2016

The activity of bacterial alkaline phosphatase (PhoA) is dependent on it being exported across the plasma membrane. A plasmid vector (pJEM11) allowing fusions between phoA and genes encoding exported proteins was constructed to study protein export in mycobacteria. Introduction of the Mycobacterium fortuitum beta-lactamase gene (blaF*) into this vector led to the production in M. smegmatis of protein fusions with PhoA activity. A genomic library from M. tuberculosis was constructed in pJEM11 and screened in M. smegmatis for clones with PhoA activity. Sequences of the M. tuberculosis inserts directing the production of protein fusions in these PhoA-positive clones were determined. They include part of the already-known exported 19-kDa lipoprotein, a sequence with similarities to the exported 28-kDa antigen from M. leprae, a sequence encoding a protein sharing conserved amino acid motifs with stearoyl-acyl-carrier-protein desaturases, and unknown sequences. This approach thus appears to identify sequences directing protein export, and we expect that more extensive screening of such libraries will lead to a better understanding of protein export in M. tuberculosis.
Lack of production of (p)ppGpp in Halobacterium volcanii under conditions that are effective in the eubacteria
Authors: Scoarughi G L , Cimmino C , Donini P
Published: November 2016

The stringent halobacterial strain Haloferax volcanii was subjected to a set of physiological conditions different from amino acid starvation that are known to cause production of guanosine polyphosphates [(p)pp Gpp] in eubacteria via the relA-independent (spoT) pathway. The conditions used were temperature upshift, treatment with cyanide, and total starvation. Under none of these conditions were detectable levels of (p)ppGpp observed. This result, in conjunction with our previous finding that (p)ppGpp synthesis does not occur under amino acid starvation, leads to the conclusion that in halobacteria both growth rate control and stringency are probably governed by mechanisms that operate in the absence of ppGpp. During exponential growth, a low level of phosphorylated compounds with electrophoretic mobilities similar, but not identical, to that of (p)ppGpp were observed. The intracellular concentration of these compounds increased considerably during the stationary phase of growth and with all of the treatments used. The compounds were identified as short-chain polyphosphates identical to those found under similar conditions in Saccharomyces cerevisiae.