bluuebunny/crossref_metadata_2025 huggingface dataset:
Novel Heat Sink Design Utilizing Ionic Wind for Efficient Passive Thermal Management of Grid-Scale Power Routers
Authors: Gallandat Noris , Rhett Mayor J.
Published: March 2015

This paper presents a numerical model assessing the potential of ionic wind as a heat transfer enhancement method for the cooling of grid distribution assets. Distribution scale power routers (13–37 kV, 1–10 MW) have stringent requirements regarding lifetime and reliability, so that any cooling technique involving moving parts such as fans or pumps are not viable. A new heat sink design combining corona electrodes with bonded fin arrays is presented. The model of the suggested design is solved numerically. It is predicted that applying a voltage of 5 kV on the corona electrodes could increase the heat removed by a factor of five as compared to natural convection.
Annular Flow Characteristics of Pseudoplastic Fluids
Authors: Dosunmu Idowu T. , Shah Subhash N.
Published: March 2015

In this paper, the problem of axial annular flow of non-Newtonian fluids is examined. By utilizing the slot analogy, a Fanning friction factor—Reynolds number relationship for a power law fluid was developed and presented. Good agreement over the entire range of flow regimes was obtained between model predictions and experimental data. The advantage of the proposed approach is that it eliminates the need to determine the dimensionless radial position of zero shear stress required to solve flow equations. Practical applications of this work include processes in the petroleum and chemical industries in which annular flow of non-Newtonian fluids is a common occurrence.
Effect of Biodiesel on Biofilm Biodeterioration of Linear Low Density Polyethylene in a Simulated Fuel Storage Tank
Authors: Restrepo-Flórez Juan-Manuel , Wood Jeffery A. , Rehmann Lars , Thompson Michael , Bassi Amarjeet
Published: March 2015

A simulated fuel storage tank was used to study biodeterioration of linear low-density polyethylene over 100 days. The system consisted of a water layer inoculated with microorganisms and a fuel layer of diesel/biodiesel. Biodeterioration was characterized measuring: biofilm growth, surface chemistry, crystallinity, and topography. Results showed greater accumulation of biofilm at higher biodiesel concentrations. Polyethylene biodegradation measured as consumption of oxidized species, increase in contact angle with water and reduction in electron donor groups was observed in all samples and was slightly higher in biodiesel-rich fuels. Topography changes and weight loss showed that microbial penetration in the polymer was superficial.
Efficient Wind Energy Conversion: Evolution to Modern Design
Authors: Gupta Ashwani K.
Published: March 2015

The vast dimensions of the renewable energy field have drawn diverse approaches, resources, and results for a long time. The continual changing behaviors and cycles of renewable energy have encouraged novel developments over the years with most commonly used approaches being three blade designs mounted on a rotor and are commonly used to harvest onshore and offshore wind energy. The renewable energy field is extremely dynamic and perplexing, thus creating a heavy interest in discovering the most economical, efficient, and reliable method to harvest renewable wind energy. Producing energy through the wind is well proven and widely used method with current activities focused on improving efficiency, performance, and reliability. A major challenge of wind energy is that it is available only when and where winds prevail. The electricity produced must be used instantly or stored for use in times when none to limited winds exist. The developments of blades have been based on the aircraft propeller design but extended over a larger area to capture much energy from the wind. This paper provides some basic guidelines on the optimum design staring from the historical design, recent developments, and opportunities. Some challenges on trends are discussed with novel ideas of some future wind energy harvesting designs for enhanced applications at greater efficiency.
Natural Gas for High Load Dual-Fuel Reactivity Controlled Compression Ignition in Heavy-Duty Engines
Authors: Ryan Walker N. , Wissink Martin L. , DelVescovo Dan A. , Reitz Rolf D.
Published: March 2015

Reactivity controlled compression ignition (RCCI) has been shown to be capable of providing improved engine efficiencies coupled with the benefit of low emissions via in-cylinder fuel blending. Much of the previous body of work has studied the use of gasoline as the premixed low-reactivity fuel. However, there is interest in exploring the use of alternative fuels in advanced combustion strategies. Due to the strong market growth of natural gas as a fuel in both mobile and stationary applications, a study on the use of methane for RCCI combustion was performed. Single cylinder heavy-duty engine experiments were undertaken to examine the operating range of the RCCI combustion strategy with methane/diesel fueling and were compared against gasoline/diesel RCCI operation. The experimental results show a significant load extension of RCCI engine operation with methane/diesel fueling compared to gasoline/diesel fueling. For gasoline/diesel fueling, a maximum load of 6.9 bar gross indicated mean effective pressure (IMEPg) at CA50 = 0 deg aTDC (after top dead center) and 7.0 bar IMEPg at CA50 = 4 deg aTDC was obtained without use of exhaust gas recirculation (EGR). For methane/diesel fueling, a maximum load of 15.4 bar IMEPg at CA50 = 0 deg aTDC and 17.3 bar IMEPg at CA50 = 4 deg aTDC was achieved, showing the effectiveness of the use of methane in extending the load limit for RCCI engine operation.
Analysis of Hydraulic Fracturing and Reservoir Performance in Enhanced Geothermal Systems
Authors: Li Mengying , Lior Noam
Published: March 2015

Analyses of fracturing and thermal performance of fractured reservoirs in engineered geothermal system (EGS) are extended from a depth of 5 km to 10 km, and models for flow and heat transfer in EGS are improved. Effects of the geofluid flow direction choice, distance between fractures, fracture width, permeability, radius, and number of fractures, on reservoir heat drawdown time are computed. The number of fractures and fracture radius for desired reservoir thermal drawdown rates are recommended. A simplified model for reservoir hydraulic fracturing energy consumption is developed, indicating it to be 51.8–99.6 MJ per m3 fracture for depths of 5–10 km.
Kepler's Third Law and NASA's Kepler Mission
Authors: Gould Alan , Komatsu Toshi , DeVore Edna , Harman Pamela , Koch David
Published: March 2015

NASA's Kepler Mission (Fig. 1) has been wildly successful in discovering exoplanets. This paper summarizes the mission goals, briefly explains the transit method of finding exoplanets and design of the mission, provides some key findings, and describes useful education materials available at the Kepler website.
Light-Emitting Diodes: Learning New Physics
Authors: Planinšič Gorazd , Etkina Eugenia
Published: March 2015

This is the third paper in our Light-Emitting Diodes series. The series aims to create a systematic library of LED-based materials and to provide the readers with the description of experiments and pedagogical treatment that would help their students construct, test, and apply physics concepts and mathematical relations. The first paper, published in the February 2014 issue of TPT,1 provided an overview of possible uses of LEDs in a physics course. The second paper2 discussed how one could help students learn the foundational aspects of LED physics through a scaffolded inquiry approach, specifically the ISLE cycle. The goals of this paper are to show how the activities described in our second paper help to deepen student understanding of physics and to broaden student knowledge by exploring new phenomena such as fluorescence. Activities described in this paper are suitable for advanced high school courses, introductory courses for physics and engineering majors, courses for prospective physics teachers, and professional development programs.
Precession of a Spinning Ball Rolling Down an Inclined Plane
Authors: Cross Rod
Published: March 2015

A routine problem in an introductory physics course considers a rectangular block at rest on a plane inclined at angle α to the horizontal. In order for the block not to slide down the incline, the coefficient of sliding friction, μ, must be at least tan α. The situation is similar for the case of a ball rolling down an inclined plane. In order for a solid ball to roll without slipping down the inclined plane, μ must be at least (2/7) tan α. In both cases, static friction is responsible for the observed effects and one can find treatments of these topics in most introductory physics textbooks. Notice that when α = 0, no frictional force is required for the ball to roll at constant speed, just as no frictional force would be required to keep the rectangular block from sliding on a horizontal plane. In the case of a rolling ball that is accelerating, a frictional force acts to produce a torque about the center of mass and, thus, plays an important role in the acceleration of the ball, whether on a horizontal1,2 or inclined plane.
Who hires physics bachelor's degree recipients?
Authors: White Susan C.
Published: March 2015

As we saw last month, over 40% of the students who recently earned bachelor's degrees in physics enter the job market. There are employment opportunities for these graduates in all areas of the economy. When we contact graduates, we ask them where they are working, and we use their responses to compile a list of employers in each state who have recently hired a physics bachelor's degree recipient. We also produce a separate list of firms that have hired three or more physics bachelor's. These lists can be useful tools for students who want to know more about where one can find a job with a bachelor's degree in physics. The lists are available at www.aip.org/whos-hiring-physics-bachelors.
A Simple Mechanical Experiment on Exponential Growth
Authors: McGrew Ralph
Published: March 2015

With a rod, cord, pulleys, and slotted masses, students can observe and graph exponential growth in the cord tension over a factor of increase as large as several hundred. This experiment is adaptable for use either in algebra-based or calculus-based physics courses, fitting naturally with the study of sliding friction. Significant parts of the activity are accessible to students in physical science and environmental science courses.
Measuring Musical Consonance and Dissonance
Authors: LoPresto Michael C.
Published: March 2015

Most combinations of musical tones are perceived as either consonant, “pleasing” to the human ear, or dissonant, which is “not pleasing.” Despite being largely subjective in nature, sensations of consonance and dissonance can be quantified and then compared to the judgments of human subjects. The following is a description of several simple studies that can be carried out in the classroom of a physics of music or science of sound course.
A Bit of Quantum Mechanics
Authors: Oss Stefano , Rosi Tommaso
Published: March 2015

We have developed an app for iOS-based smart-phones/tablets that allows a 3-D, complex phase-based colorful visualization of hydrogen atom wave functions. Several important features of the quantum behavior of atomic orbitals can easily be made evident, thus making this app a useful companion in introductory modern physics classes. There are many reasons why quantum mechanical systems and phenomena are difficult both to teach and deeply understand. They are described by equations that are generally hard to visualize, and they often oppose the so-called “common sense” based on the human perception of the world, which is built on mental images such as locality and causality. Moreover students cannot have direct experience of those systems and solutions, and generally do not even have the possibility to refer to pictures, videos, or experiments to fill this gap. Teachers often encounter quite serious troubles in finding out a sensible way to speak about the wonders of quantum physics at the high school level, where complex formalisms are not accessible at all. One should however consider that this is quite a common issue in physics and, more generally, in science education. There are plenty of natural phenomena whose models (not only at microscopic and atomic levels) are of difficult, if not impossible, visualization. Just think of certain kinds of waves, fields of forces, velocities, energy, angular momentum, and so on. One should also notice that physical reality is not the same as the images we make of it. Pictures (formal, abstract ones, as well as artists' views) are a convenient bridge between these two aspects.
Photogate Timing with a Smartphone
Authors: Forinash Kyle , Wisman Raymond F.
Published: March 2015

In a previous article we demonstrated that a simple, passive external circuit incorporating a thermistor, connected to a mobile device through the headset jack, can be used to collect temperature data.1 The basic approach is to output a sine wave signal to the headset port, through the circuit, and input the resulting signal from the headset microphone. By replacing the thermistor with other variable resistors, the circuit can perform other data measurements. A photoresistor in the circuit will change the amplitude of the returning signal by varying the resistance, depending upon the intensity of light reaching it. The circuit used is shown in Fig. 1 (a discussion of alternative circuits is given in Ref. 2). Two or more photoresistors can be placed in series to form multiple photogates, as shown in Fig. 2. The photoresistors used here have a resistance of about 120 kΩ in the dark and 5 kΩ under lamp light. Ordinary household lamps were used as light sources.
Cell Phone RF Radiation
Authors: Abdul-Razzaq Wathiq
Published: March 2015

In a recent article in Physics Today, Meredith and Redish emphasized the need to make introductory physics courses beneficial for life sciences majors.1 In this study, a lab activity is proposed to measure the intensity of electromagnetic waves emitted by cell phones and connect these measurements to various standards, biological topics, and personal health.
Resonance in a head massager
Authors: Ribeiro Jair Lúcio Prados
Published: March 2015

Mechanical structures such as pendula, bridges, or buildings always exhibit one (or more) natural oscillation frequency.1 If that structure is subjected to oscillatory forces of this same frequency, resonance occurs, with consequent increase of the structure oscillation amplitude. There is no shortage of simple experiments for demonstrating resonance in high school classes using a variety of materials, such as saw blades,2 guitars,3 pendulums,4 wine glasses,5 bottles,6 Ping-Pong balls,7 and pearl strings.8 We present here an experimental demonstration using only an inexpensive head (or scalp) massager, which can be purchased for less than a dollar.
Measuring the acoustic response of Helmholtz resonators
Authors: Monteiro Martín , Marti Arturo C. , Vogt Patrik , Kasper Lutz , Quarthal Dominik
Published: March 2015

Many experiments have been proposed to investigate acoustic phenomena in college and early undergraduate levels, in particular the speed of sound,1–9 by means of different methods, such as time of flight, transit time, or resonance in tubes. In this paper we propose to measure the acoustic response curves of a glass beaker filled with different gases, used as an acoustic resonator. We show that these curves expose many interesting peaks and features, one of which matches the resonance peak predicted for a Helmholtz resonator fairly well, and gives a decent estimate for the speed of sound in some cases. The measures are obtained thanks to the capabilities of smartphones.
Reproduction of a higher-order circular harmonic field using a linear array of loudspeakers
Authors: Lee Jung-Min , Choi Jung-Woo , Kim Yang-Hann
Published: March 2015

This paper presents a direct formula for reproducing a sound field consisting of higher-order circular harmonics with polar phase variation. Sound fields with phase variation can be used for synthesizing various spatial attributes, such as the perceived width or the location of a virtual sound source. To reproduce such a sound field using a linear loudspeaker array, the driving function of the array is derived in the format of an integral formula. The proposed function shows fewer reproduction errors than a conventional formula focused on magnitude variations. In addition, analysis of the sweet spot reveals that its shape can be asymmetric, depending on the order of harmonics.
The mobility of single-file water molecules is governed by the number of H-bonds they may form with channel-lining residues
Authors: Horner Andreas , Zocher Florian , Preiner Johannes , Ollinger Nicole , Siligan Christine , Akimov Sergey A. , Pohl Peter
Published: March 2015

Mobility of single-file water molecules determined by H-bonds.
Structural patterns at all scales in a nonmetallic chiral Au
133
(SR)
52
nanoparticle
Authors: Zeng Chenjie , Chen Yuxiang , Kirschbaum Kristin , Appavoo Kannatassen , Sfeir Matthew Y. , Jin Rongchao
Published: March 2015

X-ray crystallography unravels molecular self-assembly and structural ordering on the curved surface of the largest gold nanoparticle, consisting of 133 atoms.
Habitat fragmentation and its lasting impact on Earth’s ecosystems
Authors: Haddad Nick M. , Brudvig Lars A. , Clobert Jean , Davies Kendi F. , Gonzalez Andrew , Holt Robert D. , Lovejoy Thomas E. , Sexton Joseph O. , Austin Mike P. , Collins Cathy D. , Cook William M. , Damschen Ellen I. , Ewers Robert M. , Foster Bryan L. , Jenkins Clinton N. , King Andrew J. , Laurance William F. , Levey Douglas J. , Margules Chris R. , Melbourne Brett A. , Nicholls A. O. , Orrock John L. , Song Dan-Xia , Townshend John R.
Published: March 2015

Urgent need for conservation and restoration measures to improve landscape connectivity.
Virucidal Effect of Cold Atmospheric Gaseous Plasma on Feline Calicivirus, a Surrogate for Human Norovirus
Authors: Aboubakr Hamada A. , Williams Paul , Gangal Urvashi , Youssef Mohammed M. , El-Sohaimy Sobhy A. A. , Bruggeman Peter J. , Goyal Sagar M.
Published: March 2015

Minimal food-processing methods are not effective against foodborne viruses, such as human norovirus (NV). It is important, therefore, to explore novel nonthermal technologies for decontamination of foods eaten fresh, minimally processed and ready-to-eat foods, and food contact surfaces. We studied the
in vitro
virucidal activity of cold atmospheric gaseous plasma (CGP) against feline calicivirus (FCV), a surrogate of NV. Factors affecting the virucidal activity of CGP (a so-called radio frequency atmospheric pressure plasma jet) were the plasma generation power, the exposure time and distance, the plasma feed gas mixture, and the virus suspension medium. Exposure to 2.5-W argon (Ar) plasma caused a 5.55 log
10
unit reduction in the FCV titer within 120 s. The reduction in the virus titer increased with increasing exposure time and decreasing exposure distance. Of the four plasma gas mixtures studied (Ar, Ar plus 1% O
2
, Ar plus 1% dry air, and Ar plus 0.27% water), Ar plus 1% O
2
plasma treatment had the highest virucidal effect: more than 6.0 log
10
units of the virus after 15 s of exposure. The lowest virus reduction was observed with Ar plus 0.27% water plasma treatment (5 log
10
unit reduction after 120 s). The highest reduction in titer was observed when the virus was suspended in distilled water. Changes in temperature and pH and formation of H
2
O
2
were not responsible for the virucidal effect of plasma. The oxidation of viral capsid proteins by plasma-produced reactive oxygen and nitrogen species in the solution was thought to be responsible for the virucidal effect. In conclusion, CGP exhibits virucidal activity
in vitro
and has the potential to combat viral contamination in foods and on food preparation surfaces.
Identification of a New
cry1I
-Type Gene as a Candidate for Gene Pyramiding in Corn To Control Ostrinia Species Larvae
Authors: Zhao Can , Jurat-Fuentes Juan Luis , Abdelgaffar Heba M. , Pan Hongyu , Song Fuping , Zhang Jie
Published: March 2015

Pyramiding of diverse
cry
toxin genes from
Bacillus thuringiensis
with different modes of action is a desirable strategy to delay the evolution of resistance in the European corn borer (
Ostrinia nubilalis
). Considering the dependency of susceptibility to Cry toxins on toxin binding to receptors in the midgut of target pests, a diverse mode of action is commonly defined as recognition of unique binding sites in the target insect. In this study, we present a novel
cry1Ie
toxin gene (
cry1Ie2
) as a candidate for pyramiding with Cry1Ab or Cry1Fa in corn to control
Ostrinia
species larvae. The new toxin gene encodes an 81-kDa protein that is processed to a protease-resistant core form of approximately 55 kDa by trypsin digestion. The purified protoxin displayed high toxicity to
Ostrinia furnacalis
and
O. nubilalis
larvae but low to no activity against
Spodoptera
or heliothine species or the coleopteran
Tenebrio molitor
. Results of binding assays with
125
I-labeled Cry1Ab toxin and brush border membrane vesicles from
O. nubilalis
larvae demonstrated that Cry1Ie2 does not recognize the Cry1Ab binding sites in that insect. Reciprocal competition binding assays with biotin-labeled Cry1Ie2 confirmed the lack of shared sites with Cry1Ab or Cry1Fa in
O. nubilalis
brush border membrane vesicles. These data support Cry1Ie2 as a good candidate for pyramiding with Cry1Ab or Cry1Fa in corn to increase the control of
O. nubilalis
and reduce the risk of resistance evolution.
Genetic Diversity and Pathogenic Potential of Attaching and Effacing Escherichia coli O26:H11 Strains Recovered from Bovine Feces in the United States
Authors: Ison Sarah A. , Delannoy Sabine , Bugarel Marie , Nightingale Kendra K. , Webb Hattie E. , Renter David G. , Nagaraja Tiruvoor G. , Loneragan Guy H. , Fach Patrick
Published: March 2015

Escherichia coli
O26 has been identified as the most common non-O157 Shiga toxin-producing
E. coli
(STEC) serogroup to cause human illnesses in the United States and has been implicated in outbreaks around the world.
E. coli
has high genomic plasticity, which facilitates the loss or acquisition of virulence genes. Attaching and effacing
E. coli
(AEEC) O26 strains have frequently been isolated from bovine feces, and there is a need to better characterize the relatedness of these strains to defined molecular pathotypes and to describe the extent of their genetic diversity. High-throughput real-time PCR was used to screen 178
E. coli
O26 isolates from a single U.S. cattle feedlot, collected from May to July 2011, for the presence or absence of 25 O26 serogroup-specific and virulence-associated markers. The selected markers were capable of distinguishing these strains into molecularly defined groups (yielding 18 unique marker combinations). Analysis of the clustered regularly interspaced short palindromic repeat 1 (CRISPR1) and CRISPR2a loci further discriminated isolates into 24 CRISPR types. The combination of molecular markers and CRISPR typing provided 20.8% diversity. The recent CRISPR PCR target SP_O26-E, which was previously identified only in
stx
2
-positive O26:H11 human clinical strains, was identified in 96.4% (161/167 [95% confidence interval, 99.2 to 93.6%]) of the
stx
-negative AEEC O26:H11 bovine fecal strains. This supports that these
stx
-negative strains may have previously contained a prophage carrying
stx
or could acquire this prophage, thus possibly giving them the potential to become pathogenic to humans. These results show that investigation of specific genetic markers may further elucidate our understanding of the genetic diversity of AEEC O26 strains in bovine feces.
Lantibiotic Reductase LtnJ Substrate Selectivity Assessed with a Collection of Nisin Derivatives as Substrates
Authors: Mu Dongdong , Montalbán-López Manuel , Deng Jingjing , Kuipers Oscar P.
Published: March 2015

Lantibiotics are potent antimicrobial peptides characterized by the presence of dehydrated amino acids, dehydroalanine and dehydrobutyrine, and (methyl)lanthionine rings. In addition to these posttranslational modifications, some lantibiotics exhibit additional modifications that usually confer increased biological activity or stability on the peptide. LtnJ is a reductase responsible for the introduction of
d
-alanine in the lantibiotic lacticin 3147. The conversion of
l
-serine into
d
-alanine requires dehydroalanine as the substrate, which is produced
in vivo
by the dehydration of serine by a lantibiotic dehydratase, i.e., LanB or LanM. In this work, we probe the substrate specificity of LtnJ using a system that combines the nisin modification machinery (dehydratase, cyclase, and transporter) and the stereospecific reductase LtnJ in
Lactococcus lactis
. We also describe an improvement in the production yield of this system by inserting a putative attenuator from the nisin biosynthesis gene cluster in front of the
ltnJ
gene. In order to clarify the sequence selectivity of LtnJ, peptides composed of truncated nisin and different mutated C-terminal tails were designed and coexpressed with LtnJ and the nisin biosynthetic machinery. In these tails, serine was flanked by diverse amino acids to determine the influence of the surrounding residues in the reaction. LtnJ successfully hydrogenated peptides when hydrophobic residues (Leu, Ile, Phe, and Ala) were flanking the intermediate dehydroalanine, while those in which dehydroalanine was flanked by one or two polar residues (Ser, Thr, Glu, Lys, and Asn) or Gly were either less prone to be modified by LtnJ or not modified at all. Moreover, our results showed that dehydrobutyrine cannot serve as a substrate for LtnJ.
Gene Loss and Lineage-Specific Restriction-Modification Systems Associated with Niche Differentiation in the Campylobacter jejuni Sequence Type 403 Clonal Complex
Authors: Morley Laura , McNally Alan , Paszkiewicz Konrad , Corander Jukka , Méric Guillaume , Sheppard Samuel K. , Blom Jochen , Manning Georgina
Published: March 2015

Campylobacter jejuni
is a highly diverse species of bacteria commonly associated with infectious intestinal disease of humans and zoonotic carriage in poultry, cattle, pigs, and other animals. The species contains a large number of distinct clonal complexes that vary from host generalist lineages commonly found in poultry, livestock, and human disease cases to host-adapted specialized lineages primarily associated with livestock or poultry. Here, we present novel data on the ST403 clonal complex of
C. jejuni
, a lineage that has not been reported in avian hosts. Our data show that the lineage exhibits a distinctive pattern of intralineage recombination that is accompanied by the presence of lineage-specific restriction-modification systems. Furthermore, we show that the ST403 complex has undergone gene decay at a number of loci. Our data provide a putative link between the lack of association with avian hosts of
C. jejuni
ST403 and both gene gain and gene loss through nonsense mutations in coding sequences of genes, resulting in pseudogene formation.
In-Frame and Unmarked Gene Deletions in Burkholderia cenocepacia via an Allelic Exchange System Compatible with Gateway Technology
Authors: Fazli Mustafa , Harrison Joe J. , Gambino Michela , Givskov Michael , Tolker-Nielsen Tim
Published: March 2015

Burkholderia cenocepacia
is an emerging opportunistic pathogen causing life-threatening infections in immunocompromised individuals and in patients with cystic fibrosis, which are often difficult, if not impossible, to treat. Understanding the genetic basis of virulence in this emerging pathogen is important for the development of novel treatment regimes. Generation of deletion mutations in genes predicted to encode virulence determinants is fundamental to investigating the mechanisms of pathogenesis. However, there is a lack of appropriate selectable and counterselectable markers for use in
B. cenocepacia
, making its genetic manipulation problematic. Here we describe a Gateway-compatible allelic exchange system based on the counterselectable
pheS
gene and the I-SceI homing endonuclease. This system provides efficiency in cloning homology regions of target genes and allows the generation of precise and unmarked gene deletions in
B. cenocepacia
. As a proof of concept, we demonstrate its utility by deleting the
Bcam1349
gene, encoding a cyclic di-GMP (c-di-GMP)-responsive regulator protein important for biofilm formation.
One-Pot Production of
l
-
threo
-3-Hydroxyaspartic Acid Using Asparaginase-Deficient Escherichia coli Expressing Asparagine Hydroxylase of Streptomyces coelicolor A3(2)
Authors: Hara Ryotaro , Nakano Masashi , Kino Kuniki
Published: March 2015

We developed a novel process for efficient synthesis of
l
-
threo
-3-hydroxyaspartic acid (
l
-THA) using microbial hydroxylase and hydrolase. A well-characterized mutant of asparagine hydroxylase (AsnO-D241N) and its homologous enzyme (SCO2693-D246N) were adaptable to the direct hydroxylation of
l
-aspartic acid; however, the yields were strictly low. Therefore, the highly stable and efficient wild-type asparagine hydroxylases AsnO and SCO2693 were employed to synthesize
l
-THA. By using these recombinant enzymes,
l
-THA was obtained by
l
-asparagine hydroxylation by AsnO followed by amide hydrolysis by asparaginase via 3-hydroxyasparagine. Subsequently, the two-step reaction was adapted to one-pot bioconversion in a test tube.
l
-THA was obtained in a small amount with a molar yield of 0.076% by using intact
Escherichia coli
expressing the
asnO
gene, and thus, two asparaginase-deficient mutants of
E. coli
were investigated. A remarkably increased
l
-THA yield of 8.2% was obtained with the asparaginase I-deficient mutant. When the expression level of the
asnO
gene was enhanced by using the T7 promoter in
E. coli
instead of the
lac
promoter, the
l
-THA yield was significantly increased to 92%. By using a combination of the
E. coli
asparaginase I-deficient mutant and the T7 expression system, a whole-cell reaction in a jar fermentor was conducted, and consequently,
l
-THA was successfully obtained from
l
-asparagine with a maximum yield of 96% in less time than with test tube-scale production. These results indicate that asparagine hydroxylation followed by hydrolysis would be applicable to the efficient production of
l
-THA.
Hierarchy of Carbon Source Utilization in Soil Bacteria: Hegemonic Preference for Benzoate in Complex Aromatic Compound Mixtures Degraded by Cupriavidus pinatubonensis Strain JMP134
Authors: Pérez-Pantoja Danilo , Leiva-Novoa Pablo , Donoso Raúl A. , Little Cedric , Godoy Margarita , Pieper Dietmar H. , González Bernardo
Published: March 2015

Cupriavidus pinatubonensis
JMP134, like many other environmental bacteria, uses a range of aromatic compounds as carbon sources. Previous reports have shown a preference for benzoate when this bacterium grows on binary mixtures composed of this aromatic compound and 4-hydroxybenzoate or phenol. However, this observation has not been extended to other aromatic mixtures resembling a more archetypal context. We carried out a systematic study on the substrate preference of
C. pinatubonensis
JMP134 growing on representative aromatic compounds channeled through different catabolic pathways described in aerobic bacteria. Growth tests of nearly the entire set of binary combinations and in mixtures composed of 5 or 6 aromatic components showed that benzoate and phenol were always the preferred and deferred growth substrates, respectively. This pattern was supported by kinetic analyses that showed shorter times to initiate consumption of benzoate in aromatic compound mixtures. Gene expression analysis by real-time reverse transcription-PCR (RT-PCR) showed that, in all mixtures, the repression by benzoate over other catabolic pathways was exerted mainly at the transcriptional level. Additionally, inhibition of benzoate catabolism suggests that its multiple repressive actions are not mediated by a sole mechanism, as suggested by dissimilar requirements of benzoate degradation for effective repression in different aromatic compound mixtures. The hegemonic preference for benzoate over multiple aromatic carbon sources is not explained on the basis of growth rate and/or biomass yield on each single substrate or by obvious chemical or metabolic properties of these aromatic compounds.
Houseflies (Musca domestica) as Vectors for Extended-Spectrum β-Lactamase-Producing Escherichia coli on Spanish Broiler Farms
Authors: Solà-Ginés Marc , González-López Juan José , Cameron-Veas Karla , Piedra-Carrasco Nuria , Cerdà-Cuéllar Marta , Migura-Garcia Lourdes
Published: March 2015

Flies may act as potential vectors for the spread of resistant bacteria to different environments. This study was intended to evaluate the presence of
Escherichia coli
strains resistant to cephalosporins in flies captured in the areas surrounding five broiler farms. Phenotypic and molecular characterization of the resistant population was performed by different methods: MIC determination, pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and phylotyping. The presence of extended-spectrum beta-lactamase (ESBL) genes, their plasmid location, and the mobile genetic elements involved in their mobilization were studied. Additionally, the presence of 35 genes associated with virulence was evaluated. Out of 682 flies captured, 42 yielded ESBL-producing
E. coli
. Of these isolates, 23 contained
bla
CTX-M-1
, 18 contained
bla
CTX-M-14
, and 1 contained
bla
CTX-M-9
. ESBL genes were associated mainly with the presence of the IncI1 and IncFIB replicons. Additionally, all the strains were multiresistant, and five of them also harbored
qnrS
. Identical PFGE profiles were found for
E. coli
isolates obtained from flies at different sampling times, indicating a persistence of the same clones in the farm environment over months. According to their virulence genes, 81% of the isolates were considered avian-pathogenic
E. coli
(APEC) and 29% were considered extraintestinal pathogenic
E. coli
(ExPEC). The entrance of flies into broiler houses constitutes a considerable risk for colonization of broilers with multidrug-resistant
E. coli
. ESBLs in flies reflect the contamination status of the farm environment. Additionally, this study demonstrates the potential contribution of flies to the dissemination of virulence and resistance genes into different ecological niches.
Unusual Case of Pyogenic Spondylodiscitis, Vertebral Osteomyelitis and Bilateral Psoas Abscesses after Acupuncture: Diagnosis and Treatment with Interventional Management
Authors: He Chengjian , Wang Tao , Gu Yifeng , Tian Qinghua , Zhou Bi , Wu Chungen
Published: March 2015

Background

We report, for the first time, a case of pyogenic spondylodiscitis combined with vertebral osteomyelitis and bilateral psoas abscesses after acupuncture.

Case History

A 60-year-old man was diagnosed with rectal cancer, and radical rectectomy and permanent colostomy were carried out. However, 3 years after the surgery the patient complained of pain in the lower back, and the symptoms worsened after seven sessions of acupuncture. Technetium 99m-labelled methylene diphosphonate (99mTc-MDP) bone scintigraphy (BS) revealed abnormal uptake of 99mTc-MDP in the L4 and L5 vertebrae. He was admitted to our hospital because of suspected bone metastases from rectal cancer. He was diagnosed with infection based on a history of acupuncture and the findings of enhanced MRI and CT. Percutaneous lumbar discectomy (PLD), external drainage and irrigation using antibiotics were carried out to treat the L4−5 disc. Pathological analyses and bacterial culture of the resected disc confirmed infection with group C streptococcus. Postoperative antibiotic treatment resulted in significant pain relief on the third day and gradual complete relief. Considerable improvement was seen on CT and MRI at follow-up.

Conclusions

We consider it highly likely that this patient's infection was caused by acupuncture. In patients with malignancy, abnormal uptake of 99mTc-MDP in BS may signify bone metastasis but can also be observed in bone infections. PLD can be used to resect diseased discs to relieve pain quickly and to prevent herniation of lumbar discs. After PLD, external drainage can be employed for abscess drainage, decompression and perfusion of antibiotics. PLD may serve as an alternative to open surgery for pyogenic spondylodiscitis.
Oesophageal perforation caused by screw displacement 16 months following anterior cervical spine fixation
Authors: Leaver Nicholas , Colby Alexandra , Appleton Nathan , Vimalachandran Dale
Published: March 2015

Anterior cervical spine plating is a standard procedure for fixing unstable vertebral fractures. Following surgery, oesophageal perforation has an incidence of 0.25% and this is usually hours following surgery, due to over prominent screws or friction between the oesophagus and the plate. Instrumentation failure of these plates months or years following surgery is very rare but potentially life-threatening. We report a case of microcytic anaemia which was investigated by oesophagogastroduodenoscopy, and subsequently found that a screw from the anterior plate had lifted off and perforated the oesophagus. This is very rare, but emphasises an important lesson. Anyone presenting with gastrointestinal bleeding or infectious signs, with a history of cervical spine plating should be investigated immediately for instrumentation failure as it brings a high mortality.
Healthcare resource implications of hypoglycemia-related hospital admissions and inpatient hypoglycemia: retrospective record-linked cohort studies in England
Authors: McEwan Philip , Larsen Thorsted Brian , Wolden Michael , Jacobsen Judith , Evans Marc
Published: March 2015

Objective

Using a retrospective cohort study, the mean length of hospital stay (LoS) and total per-patient expenditure for hypoglycemia requiring admission to hospital were estimated. In a separate matched retrospective cohort study, the effect of inpatient hypoglycemia on LoS, expenditure, and risk of all-cause mortality while admitted was investigated.

Methods

The cohorts consisted of patients aged ≥18 years with a diagnosis of type 1 or 2 diabetes between January 1, 2002 and October 30, 2012 in the Clinical Practice Research Datalink database, who had initiated insulin treatment and had a recording of hypoglycemia in the same period. In the matched retrospective cohort study, exposed patients (who experienced hypoglycemia in hospital) were case-matched with patients who did not experience hypoglycemia during admission (unexposed). Generalized linear regression was used to estimate LoS. Risk of all-cause mortality was evaluated via logistic regression.

Results

In the retrospective cohort study (1131 patients), mean LoS was 5.46 (95% CI 4.62 to 6.45) days for type 1 diabetes, and 5.04 (95% CI 4.46 to 5.71) days for type 2 diabetes. Mean cost per admission was £1034 (95% CI £855 to £1253). In the matched retrospective cohort study (1079 pairs of patients), exposed patients had a mean LoS of 11.91 days (95% CI 10.96 to 12.94 days) versus 4.80 (95% CI 4.41 to 5.23) for unexposed patients, p<0.0001. Exposed patients had a higher mortality risk compared with unexposed patients (OR 1.439 (95% CI 1.060to 1.952), p=0.0195). Total average per-patient cost for exposed patients was GBP (£)2235, 40% (p<0.0001) higher than total average admission cost in unexposed patients.

Conclusions

Hypoglycemia has a significant negative impact on patient outcomes, healthcare resource use, and expenditure.
Effectiveness of general preconception care accompanied by a recruitment approach: protocol of a community-based cohort study (the Healthy Pregnancy 4 All study)
Authors: van Voorst Sabine F , Vos Amber A , de Jong-Potjer Lieke C , Waelput Adja J M , Steegers Eric A P , Denktas¸ Semiha
Published: March 2015

Introduction

Promotion of healthy pregnancies has gained high priority in the Netherlands because of the relative unfavourable perinatal outcomes. In response, a nationwide study Healthy Pregnancy 4 All (HP4ALL) has been initiated. One of the substudies within HP4ALL focuses on preconception care (PCC). PCC is an opportunity to detect and eliminate risk factors before conception to optimise health before organogenesis and placentation. The main objectives of the PCC substudy are (1) to assess the effectiveness of a recruitment strategy for the PCC health services and (2) to assess the effectiveness of individual PCC consultations.

Methods/analysis

Prospective cohort study in neighbourhoods of 14 municipalities with perinatal mortality and morbidity rates exceeding the nation's average. The theoretical framework of the PCC substudy is based on Andersen's model of healthcare utilisation (a model that evaluates the utilisation of healthcare services from a sociological perspective). Women aged 18 up to and including 41 years are targeted for utilisation of the PCC health service by a four armed recruitment strategy. The PCC health service consists of an individual PCC consultation consisting of (1) initial risk assessment and risk management and (2) a follow-up consultation to assess adherence to the management plan. The primary outcomes regarding the effectiveness of consultations is behavioural change regarding folic acid supplementation, smoking cessation, cessation of alcohol consumption and illicit substance use. The primary outcome regarding the effectiveness of the recruitment strategy is the number of women successfully recruited and the outreach in terms of which population is reached in comparison to the approached population. Data collection consists of registration in the database of women that enrol for a visit to the individual PCC consultations (women successfully recruited), and preconsultation and postconsultation measurements among the included study population (by questionnaires, anthropometric measurements and biomarkers). Sample size calculation resulted in a sample size of n=839 women.

Ethics and dissemination

Approval for this study has been obtained from the Medical Ethical Committee of the Erasmus Medical Center of Rotterdam (MEC 2012-425). Results will be published and presented at international conferences.
Determination of risk factors for drug-related problems: a multidisciplinary triangulation process
Authors: Kaufmann Carole P , Stämpfli Dominik , Hersberger Kurt E , Lampert Markus L
Published: March 2015

Introduction and objectives

Drug-related problems (DRPs) constitute a frequent safety issue among hospitalised patients leading to patient harm and increased healthcare costs. Because many DRPs are preventable, the specific risk factors that facilitate their occurrence are of considerable interest. The objective of our study was to assess risk factors for the occurrence of DRPs with the intention to identify patients at risk for DRPs to guide and target preventive measures where they are needed most in patients.

Design

Triangulation process using a mixed methods approach.

Methods

We conducted an expert panel, using the nominal group technique (NGT) and a qualitative analysis, to gather risk factors for DRPs. The expert panel consisted of two consultant hospital physicians (internal medicine and geriatrics), one emergency physician, one independent general practitioner, one clinical pharmacologist, one clinical pharmacist, one registered nurse, one home care nurse and two independent community pharmacists. The literature was searched for additional risk factors. Gathered factors from the literature search and the NGT were assembled and validated in a two-round Delphi questionnaire.

Results

The NGT resulted in the identification of 33 items with 13 additional risk factors from the qualitative analysis of the discussion. The literature search delivered another 39 risk factors. The 85 risk factors were refined to produce 42 statements for the Delphi online questionnaire. Of these, 27 risk factors were judged to be ‘important’ or ‘rather important’.

Conclusions

The gathered risk factors may help to characterise and identify patients at risk for DRPs and may enable clinical pharmacists to guide and target preventive measures in order to limit the occurrence of DRPs. As a further step, these risk factors will serve as the basis for a screening tool to identify patients at risk for DRPs.
Remote supervision of medical training via videoconference in northern Australia: a qualitative study of the perspectives of supervisors and trainees
Authors: Cameron Miriam , Ray Robin , Sabesan Sabe
Published: March 2015

Objectives

Telemedicine has revolutionised the ability to provide care to patients, relieve professional isolation and provide guidance and supervision to junior medical officers in rural areas. This study evaluated the Townsville teleoncology supervision model for the training of junior medical officers in rural areas of North Queensland, Australia. Specifically, the perspectives of junior and senior medical officers were explored to identify recommendations for future implementation.

Design

A qualitative approach incorporating observation and semistructured interviews was used to collect data. Interviews were uploaded into NVivo 10 data management software. Template analysis enabled themes to be tested and developed through consensus between researchers.

Setting

One tertiary level and four secondary level healthcare centres in rural and regional Queensland, Australia.

Participants

10 junior medical officers (Interns, Registrars) and 10 senior medical officers (Senior Medical Officers, Consultants) who participated in the Townsville teleoncology model of remote supervision via videoconference (TTMRS) were included in the study.

Primary and Secondary outcome measures

Perspectives on the telemedicine experience, technology, engagement, professional support, satisfaction and limitations were examined. Perspectives on topics raised by participants were also examined as the interviews progressed.

Results

Four major themes with several subthemes emerged from the data: learning environment, beginning the learning relationship, stimulus for learning and practicalities of remote supervision via videoconference. While some themes were consistent with the current literature, new themes like increased professional edge, recognising non-verbal cues and physical examination challenges were identified.

Conclusions

Remote supervision via videoconference provides readily available guidance to trainees supporting their delivery of appropriate care to patients. However, resources required for upskilling, training in the use of supervision via videoconference, administration issues and nursing support, as well as physical barriers to examinations, must be addressed to enable more efficient implementation.