bluuebunny/crossref_metadata_2025 huggingface dataset:
Chlorine dioxide treatment decreases respiration and ethylene synthesis in fresh‐cut ‘Hami’ melon fruit
Authors: Guo Qin , Lv Xin , Xu Fei , Zhang Yuli , Wang Jide , Lin Honghui , Wu Bin
Published: July 2013

The effects of chlorine dioxide (ClO2) on respiration and ethylene synthesis of fresh‐cut melon fruit and the possible mechanisms involved were investigated. Fresh‐cut ‘Hami’ melon fruit fumigated with gas ClO2 in sealed container for 12 h and then stored at 5 °C with 95% relative humidity (RH) for 19 days. Results showed that fruit treated with ClO2 resulted in lower rates of the total respiration, alternative pathway respiration, cytochrome pathway respiration and ethylene production. Furthermore, the expressions of ethylene biosynthesis‐related genes, including CmACS2, CmACO1 and CmACO3 were reduced by ClO2 treatment. Taken together, it is suggested that ClO2 treatment might be an effective way to delay ripening of fresh‐cut ‘Hami’ melon, partially due to the reduced respiration and ethylene biosynthesis.
Improved energy efficiency of farmers' cooperative litchi drying operation in Northern Thailand
Authors: Precoppe Marcelo , Janjai Serm , Mahayothee Busarakorn , Müller Joachim
Published: July 2013

In 2007, Hmong farmers growing litchi in the mountainous region of Northern Thailand started to dry the fruit in response to its declining market price. However, the locally available dryer, although affordable and of a size appropriate for smallholder farmers' cooperatives, showed excessive gas consumption, and this, along with rising fuel costs, imposed a threat to the drying operation. The objective of this study was to test low‐cost, easy‐to‐implement modifications to a locally available convection dryer, to improve its energy efficiency. Experiments were conducted in cooperation with a Hmong farmers' cooperative in Northern Thailand. Insulation of the air ducts and control of the air recirculation rate led to energy cost savings of US$2.45 per dryer‐load. With the modifications required being simple, the investment needed was recovered after only approximately 20 loads, while the energy efficiency of the dryer increased from 33% to 39%.
Identification of the aroma compounds in stinky mandarin fish (Siniperca chuatsi) and comparison of volatiles during fermentation and storage
Authors: Li Chunping , Wu Jiajia , Li Yan , Dai Zhiyuan
Published: July 2013

Identification of aroma compounds in Stinky Mandarin fish (Siniperca chuatsi) and comparison of volatiles during fermentation (with spices and salt) and storage were analysed by electronic nose (e‐nose) combining with gas chromatography–mass spectrometry (GC‐MS). Among the sixty‐one detected volatiles, thirteen aroma‐active compounds, especially linalool, were identified in stinky mandarin fish according to thresholds and concentrations. Totally, twenty‐four aroma compounds correlated well with the periods of fermentation and storage. Trimethylamine, indole, sulphur‐containing compounds, acetic acid, esters and phenols increased continually, while aldehydes decreased. According to these quality indicators, e‐nose data using principal component analysis showed a clear discrimination of the fermented fish and were in good agreement with the results of GC‐MS. In conclusion, fermentation favoured to retard spoilage and provided new aroma compounds. The technique employing an e‐nose in combination with GC‐MS could compare and identify the aroma and quality of stinky mandarin fish.
The influence of wine polymers on the spontaneous precipitation of calcium tartrate in a model wine solution
Authors: Pellerin Patrice , Doco Thierry , Scollary Geoffrey R.
Published: July 2013

The influence of wine polymers on the spontaneous precipitation of calcium tartrate in a model wine system has been examined. Rhamnogalacturonan‐I was identified as the most effective inhibitor (precipitation induction time of 180 min compared with 7 min for the standard model). It is argued that this is a consequence of rhamnogalacturonan‐I's ability to participate in the ‘egg‐box’ type sequestration of calcium ions. The more structurally complex rhamnogalacturonan‐II had only a minor influence on the induction time (22 min). Arabinogalactan proteins and mannoproteins also have little influence with induction times ranging from 12 to 15 min. An ultra‐filtration study of four Chardonnay wines, prepared with and without the use of pectolytic enzymes, was performed in a search for conditions that might maximise the concentration of rhamnogalacturonan‐I. However, rhamnogalacturonan‐I could not be identified in any of the four wines. Implications of these observations, specifically the need to understand the inhibition exerted by specific uronic acids, for winemaking and calcium tartrate precipitation are discussed.
Administration of chemotherapy with palliative intent in the last 30 days of life: the balance between palliation and chemotherapy
Authors: Zdenkowski N. , Cavenagh J. , Ku Y. C. , Bisquera A. , Bonaventura A.
Published: July 2013

Background

Appropriately timed cessation of chemotherapy is an important aspect of good quality palliative care. There is wide variation in the reported rates of chemotherapy administration within the last 30 days of life.

Aims

To identify predictors of death within 30 days of receiving palliative chemotherapy, and to propose a standard definition by which oncologists and cancer centres can be compared.

Methods

Patients who received palliative chemotherapy at a regional cancer centre and its rural outreach unit between 2009 and 2011 were included. An adjusted logistic regression model, including all variables, was fit to identify predictors of death within 30 days of receiving palliative chemotherapy.

Results

Over a 3‐year period, 1131 patients received palliative chemotherapy, 138 (12%) died within 30 days of receiving palliative chemotherapy. Predictors of death within 30 days of palliative chemotherapy were: less than 30 days contact with palliative care (odds ratio 3.30 (95% confidence interval 2.04–5.34), P < 0.001) and male gender (odds ratio 2.02 (95% confidence interval 1.24–3.31), P = 0.0049), but treating clinician, tumour chemoresponsiveness, age, body mass index and survival from initial diagnosis were not.

Conclusion

Patients who received chemotherapy in the last 30 days of life were more likely to be male and have a shorter duration of palliative care team involvement. In this study, the observed rate of death within 30 days of chemotherapy is within the range of published data. It is recommended that a standard definition be used to benchmark medical oncology centres and individual oncologists, and to allow comparison over time.
Destructive periodontal disease in adult Indians from Northeast Brazil: cross‐sectional study of prevalence and risk indicators
Authors: Figueiredo Andreia , Soares Susana , Lopes Helton , dos Santos Jean Nunes , Ramalho Luciana Maria Pedreira , Cangussu Maria Cristina , Cury Patricia Ramos
Published: July 2013

Aim

The aim of this cross‐sectional study was to evaluate the prevalence of destructive periodontal disease and its risk indicators in adult Kiriri Indians from Northeast Brazil.

Materials and Methods

Full‐mouth periodontal examinations were performed on a sample of 215 Indians (≥19 years). Bivariate analyses and logistic models were applied to assess associations between periodontitis and its putative risk factors.

Results

Prevalence of clinical attachment loss of ≥3, ≥5 and ≥7 mm was 97.8%, 63.8% and 30.8% respectively. Percentage of teeth per individual showing clinical attachment loss of ≥3, ≥5 and ≥7 mm was 49.8%, 18.4% and 8.0% respectively. After adjustment for covariates, individuals aged ≥35 years (OR = 5.83, 95% CI: 3.09–11.00; p < 0.001), men (OR = 2.18, 95% CI: 1.15–4.11; p = 0.02) and diabetics (OR = 3.92, 95% CI 1.03–14.99; p = 0.05) had a higher risk for destructive periodontitis, classified according to the CDC/AAP case definition.

Conclusion

Though periodontitis was highly prevalent in Kiriri Indians, only few teeth showed advanced disease, and periodontitis was associated with higher age, male sex and diabetes. A public health action that includes programs of prevention and treatment targeting high‐risk groups is vital to improve the periodontal status of this population.
Juicy Stories on Female Reproductive Tissue Development: Coordinating the Hormone Flows
Authors: Grieneisen Verônica A. , Marée Athanasius F.M. , Østergaard Lars
Published: July 2013

In the past 20–30 years, developmental biologists have made tremendous progress in identifying genes required for the specification of individual cell types of an organ and in describing how they interact in genetic networks. In comparison, very little is known about the mechanisms that regulate tissue polarity and overall organ patterning. Gynoecia and fruits from members of the Brassicaceae family of flowering plants provide excellent model systems to study organ patterning and tissue specification because they become partitioned into distinct domains whose formation is determined by polarity establishment both at a cellular and whole tissue level. Interactions among key regulators of Arabidopsis gynoecium and fruit development have revealed a network of upstream transcription factor activities required for such tissue differentiation. Regulation of the plant hormone auxin is emerging as both an immediate downstream output and input of these activities, and here we aim to provide an overview of the current knowledge regarding the link between auxin and female reproductive development in plants. In this review, we will also demonstrate how available data can be exploited in a mathematical modeling approach to reveal and understand the feedback regulatory circuits that underpin the polarity establishment, necessary to guide auxin flows.

image

Verônica A. Grieneisen,

Athanasius F.M. Marée,

Lars Østergaard

(Corresponding authors)
Intraspecific differentiation of Allium wallichii (Amaryllidaceae) inferred from chloroplast DNA and internal transcribed spacer fragments
Authors: HUANG De‐Qing , LI Qin‐Qin , ZHOU Chun‐Jing , ZHOU Song‐Dong , HE Xing‐Jin
Published: July 2013

In the present study, we used two chloroplast DNA (cpDNA) fragments (trnL‐F and rps16) and the nuclear ribosomal internal transcribed spacer (ITS) sequence data to examine intraspecific differentiation and phylogeographical history of Allium wallichii. Based on wide scale sampling (28 populations and 174 individuals) across the entire distribution range of this species, 33 cpDNA haplotypes and 25 ITS ribotypes were detected in our investigation. These cpDNA haplotypes were divided into three major lineages, which was further supported by the ITS phylogenetic results. High haplotype/ribotype diversity and population differentiation, together with most of the haplotypes/ribotypes being exclusive to single populations, implied restricted gene flow among populations and significant geographical isolation. Nearly all populations with high haplotype/ribotype diversity were found in the Hengduan Mountain Region (HMR), whereas the populations of the Himalayas and Nanling Mountains showed a lower level, suggesting the HMR might serve as a potential divergence center for A. wallichii. The main lineages of A. wallichii diverged from each other between Mid–Late Pliocene and Early Quaternary based on two sets of molecular markers, indicating that the Quaternary climatic fluctuation could not have contributed greatly to the divergence of the main lineages of A. wallichii. Instead, the intricate topography and heterogeneous habitats resulting from the drastic uplift of the Qinghai–Tibet Plateau from the Late Pliocene could be responsible for the intraspecific differentiation of A. wallichii. The present study further highlights the importance of geographic isolation and habitat heterogeneity in shaping and maintaining high species diversity within the HMR.
Radiofrequency Ablation at Low Irrigation Flow Rates Using a Novel 12‐Hole Gold Open‐Irrigation Catheter
Authors: AKCA FERDI , ZIMA ENDRE , VÉGH ESZTER M. , SZÉPLAKI GÁBOR , SKOPÁL JUDIT , HUBAY MARTHA , LENDVAI ZSUZSANNA , MERKELY BELA , SZILI‐TOROK TAMAS
Published: July 2013

Background

High irrigation rates during radiofrequency (RF) ablation may cause fluid overload and limit lesion size. This in vivo animal study assessed the safety and efficacy of RF ablation at low irrigation rates using a novel 12‐hole gold catheter.

Methods

A total of 103 lesions, created on the thigh of five mongrel dogs, were analyzed. Lesions were created using a 12‐hole irrigated gold‐tip (Au) and a six‐hole irrigated platinum–iridium (PtIr) catheter (both 7F/3.5‐mm electrode; BIOTRONIK SE & CO, KG, Berlin, Germany) in parallel and perpendicular orientation. RF current was delivered for 60 seconds at 30 W using 8 mL/min and 15 mL/min irrigation. Electrode temperature, steam pops, lesion dimensions, and coagulum formation were recorded.

Results

Electrode temperatures were lower for Au compared to PtIr in parallel (8 mL/min: 38.1 ± 1.7°C vs 48.0 ± 4.8°C, P < 0.0001; 15 mL/min: 36.0 ± 1.5°C vs 46.9 ± 5.4°C, P < 0.0001) and perpendicular position (15 mL/min: 35.5 ± 1.2°C vs 38.4 ± 2.5°C, P = 0.003). The number of steam pops between Au and PtIr was comparable for parallel (8 mL/min: 14% vs 27%, P = 0.65; 15 mL/min: 14% vs 43%, P = 0.21) and perpendicular orientation (8 mL/min: 25% vs 17%, P = 1.00; 15 mL/min: 18% vs 0%, P = 0.48). Au created larger volumes than PtIr at 8 mL/min irrigation (861 ± 251 mm3 vs 504 ± 212 mm3, P = 0.004); however, for 15 mL/min, volumes were comparable (624 ± 269 mm3 vs 768 ± 466 mm3, P = 0.46). No coagulum formation was observed for any of the catheters on the surface and catheter tip.

Conclusion

RF ablation at low flow rate using a novel 12‐hole irrigation Au catheter is safe and results in larger lesions than with a PtIr electrode.
Smart Meters and Routers Radiofrequency Disturbances Study with Pacemakers and Implantable Cardiac Defibrillators
Authors: OSTIGUY GENEVIÈVE , BLACK TOM , BLUTEAU LOUIS‐JEAN , DUPONT LOUIS , DYRDA KATIA , GIRARD GUILLAUME , NGUYEN DUC‐HAI , PLANTE MICHEL , THIBAULT BERNARD
Published: July 2013

Background

There is no scientific literature that examines radiofrequency (RF) interference from Smart Meters with cardiac implantable electronic devices (CIEDs). The objective of this in vitro study was to assess any potential interference with Medtronic CIEDs (Medtronic Inc., Minneapolis, MN, USA).

Methods

In the Quebec testing, five models of Medtronic CIEDs were placed in an acrylic cylinder filled with a saline solution and faced a Landis+Gyr Smart Meter or Router (Landis+Gyr AG, Zug, Switzerland). The distance between CIEDs and the meter casing or router antenna was 10 cm. The Meter's normal operating conditions were modified to artificially set the number of impulsions at an abnormally high level (one, two, and three impulses per second). Each scenario was repeated one to five times, for 1 minute each. In the U.S. testing, 6 cm and 15 cm (∼2.25′ and ∼6′) separated the six models of Medtronic CIEDs from the Schlumberger Smart Meter (Itron Inc., Liberty Lake, WA, USA), which generally sent out a 96‐bit Standard Consumption Message over 3 seconds. The transmission varied in frequencies along with the interval between cycles.

Results

A total of 6,966 RF transmissions were completed during the 34 tests conducted in Quebec. In the United States, the CIED was exposed to the meter for 10 minutes to provide a minimum of 200 completed RF transmissions. No interference was observed in worst‐case scenarios (testing of meters and CIEDs at their performance limits).

Conclusions

Landis+Gyr Smart Meters/Routers and Schlumberger Smart Meters do not interfere with the functioning of the Medtronic CIEDs tested, when placed, respectively, 10 cm and 6 cm and 15 cm apart.
BUILDING FOREIGN AFFAIRS CAPACITY IN THE EU: THE RECRUITMENT OF MEMBER STATE OFFICIALS TO THE EUROPEAN EXTERNAL ACTION SERVICE (EEAS)
Authors: MURDOCH ZUZANA , TRONDAL JARLE , GÄNZLE STEFAN
Published: July 2013

The Treaty of Lisbon introduced common action capacities in the EU's external relations administration, notably the European External Action Service (EEAS). One essential capacity is staff resources. This article analyses to what extent and under what conditions the practice of staff recruitment to the EEAS isindependentof government influence, and in particular the recruitment of officials temporarily assigned from EU member states. The data draw on interviews with officials from all 27 member states as well as the EEAS which is charged with the selection of national public servants to the EEAS. Key findings suggest substantial independence of recruitment to the EEAS, and this independence is facilitated under two particular conditions: (i)the supply of administrative capacities at EU levelstrengthens the capacity of the EEAS to nurture the independent recruitment of its personnel; and (ii) the recruitment of EEAS personnel is conditioned bypre‐existing organizational traditions, practices, and formats.
Till death do us part: Terror management and forgiveness in close relationships
Authors: VAN TONGEREN DARYL R. , GREEN JEFFREY D. , DAVIS DON E. , WORTHINGTON EVERETT L. , REID CHELSEA A.
Published: July 2013

Two experiments extended terror management theory to investigate forgiveness in close relationships. We hypothesized that mortality salience would elicit less forgiveness in less committed relationships. In Experiment 1, participants were primed with either mortality salience or a physical pain control condition, recalled a recent hurtful interpersonal offense, and reported their degree of forgiveness. Mortality salience evoked less forgiveness in less committed relationships. In Experiment 2, participants were assigned to recall an offense that occurred in a low‐commitment or high‐commitment relationship. Again, mortality salience elicited less forgiveness in less committed relationships; it elicited more forgiveness in more committed relationships. Moreover, this interaction was mediated by empathy. Existential considerations may play an important role in the functioning of close relationships.
Foreword: Special Issue on Retail Operations
Authors: Fisher Marshall
Published: July 2013

This article draws on my field research in the retailing industry to identify the operational challenges faced by retailers and the relevance of those challenges to senior retail managers and researchers in operations management. It summarizes areas of research in retail operations that have evolved recently and are likely to be important in the future.
Mud dispersal across a Cretaceous prodelta: Storm‐generated, wave‐enhanced sediment gravity flows inferred from mudstone microtexture and microfacies
Authors: Guy Plint A.
Published: July 2013

Determining sediment transport direction in ancient mudrocks is difficult. In order to determine both process and direction of mud transport, a portion of a well‐mapped Cretaceous delta system was studied. Oriented samples from outcrop represent prodelta environments from ca 10 to 120 km offshore. Oriented thin sections of mudstone, cut in three planes, allowed bed microstructure and palaeoflow directions to be determined. Clay mineral platelets are packaged in equant, face‐face aggregates 2 to 5 μm in diameter that have a random orientation; these aggregates may have formed through flocculation in fluid mud. Cohesive mud was eroded by storms to make intraclastic aggregates 5 to 20 μm in diameter. Mudstone beds are millimetre‐scale, and four microfacies are recognized: Well‐sorted siltstone forms millimetre‐scale combined‐flow ripples overlying scoured surfaces; deposition was from turbulent combined flow. Silt‐streaked claystone comprises parallel, sub‐millimetre laminae of siliceous silt and clay aggregates sorted by shear in the boundary layer beneath a wave‐supported gravity flow of fluid mud. Silty claystone comprises fine siliceous silt grains floating in a matrix of clay and was deposited by vertical settling as fluid mud gelled under minimal current shear. Homogeneous clay‐rich mudstone has little silt and may represent late‐stage settling of fluid mud, or settling from wave‐dissipated fluid mud. It is difficult or impossible to correlate millimetre‐scale beds between thin sections from the same sample, spaced only ca 20 mm apart, due to lateral facies change and localized scour and fill. Combined‐flow ripples in siltstone show strong preferred migration directly down the regional prodelta slope, estimated at ca 1 : 1000. Ripple migration was effected by drag exerted by an overlying layer of downslope‐flowing, wave‐supported fluid mud. In the upper part of the studied section, centimetre‐scale interbeds of very fine to fine‐grained sandstone show wave ripple crests trending shore normal, whereas combined‐flow ripples migrated obliquely alongshore and offshore. Storm winds blowing from the north‐east drove shore‐oblique geostrophic sand transport whereas simultaneously, wave‐supported flows of fluid mud travelled downslope under the influence of gravity. Effective wave base for sand, estimated at ca 40 m, intersected the prodelta surface ca 80 km offshore whereas wave base for mud was at ca 70 m and lay ca 120 km offshore. Small‐scale bioturbation of mud beds co‐occurs with interbedded sandstone but stratigraphically lower, sand‐free mudstone has few or no signs of benthic fauna. It is likely that a combination of soupground substrate, frequent storm emplacement of fluid mud, low nutrient availability and possibly reduced bottom‐water oxygen content collectively inhibited benthic fauna in the distal prodelta.
Cryptosporidium hominis Subtypes and Enterocytozoon bieneusi Genotypes in HIV‐Infected Persons in Ibadan, Nigeria
Authors: Ayinmode A. B. , Zhang H. , Dada‐Adegbola H. O. , Xiao L.
Published: July 2013

Cryptosporidium and Enterocytozoon are common opportunistic pathogens in HIV+ patients in developing countries, especially those do not have access to antiretroviral therapy. To determine the distribution of genotypes/subtypes of Cryptosporidium and Enterocytozoon bieneusi, faecal specimens were collected from 132 HIV+ persons attending a tertiary hospital in Ibadan, Nigeria. By polymerase chain reaction, eight and ten patients were identified as positive for Cryptosporidium spp. and E. bieneusi, respectively. Seven of the Cryptosporidium specimens were identified as C. hominis, while the remaining one as the new species C. viatorum recently identified in the United Kingdom. DNA sequencing of the 60‐kDa glycoprotein gene showed that the C. hominis belonged to three common subtype families: Ia (in three patients), Ib (in one patient) and Ie (in one patient). In contrast, DNA sequencing of the E. bieneusi internal transcribed spacer products showed the occurrence of genotypes associated with both humans (Peru 8 in one patient, Nig2 in two patients and a new genotype in one patient) and animals (D in one patient and Type IV in five patients). Low CD4+ cell count was identified as a risk factor for both cryptosporidiosis and microsporidiosis.
The role of cGMP in the physiological and molecular responses of the right ventricle to pressure overload
Authors: Janssen Wiebke , Schermuly Ralph Theo , Kojonazarov Baktybek
Published: July 2013

New findings

What is the topic of this review?

The topic of the review is the physiological and molecular responses of the right ventricle to pressure overload and the role of the cGMP–phosphodiesterase 5 signalling pathway on right ventricular hypertrophy and function.

What advances does it highlight?

Right ventricular dysfunction is a major determinant of prognosis in pulmonary arterial hypertension patients. In this review, we discuss the molecular physiological/ pathophysiological response of the right ventricle to high‐pressure overload, with special emphasis on cGMP–phosphodiesterase 5 signalling.

Pulmonary arterial hypertension (PAH) is a progressive disease that is associated with a poor prognosis and results in right heart dysfunction. While pulmonary vascular disease is the obvious primary pathological focus, right ventricular hypertrophy (RVH) and right ventricular (RV) dysfunction are major determinants of prognosis in PAH. Our knowledge about the molecular physiology and pathophysiology of RV hypertrophy and failure in response to pressure overload is still limited, and most data are derived from left heart research. However, the molecular mechanisms of left ventricular remodelling cannot be generalized to the RV, because the right and left ventricles differ greatly in their size, shape, architecture and function. Despite the recent advances in diagnosis and treatment of PAH, little is known about the molecular and cellular mechanisms that underlie the transition from compensatory to maladaptive RV remodelling. The cGMP–phosphodiesterase 5 (PDE5) pathway is one of the extensively studied pathways in PAH, but our knowledge about cGMP–PDE5 signalling in RV pathophysiology is still limited. For this purpose, there is need for animal models that can represent changes in the RV that closely mimic the human situation. The availability of an animal model of pressure‐overload‐induced RVH (e.g. pulmonary artery banding model) provides us with a valuable tool to understand the differences between adaptive and maladaptive RVH and to explore the direct effects of current PAH therapy on the heart. In this report, we discuss myocardial regulatory effects of cGMP–PDE5 signalling in preclinical models of RV pressure overload for understanding the physiological/pathophysiological mechanisms involved in maladaptive RVH.
Characterization of Pyromark 2500 Paint for High-Temperature Solar Receivers
Authors: Ho Clifford K. , Mahoney A. Roderick , Ambrosini Andrea , Bencomo Marlene , Hall Aaron , Lambert Timothy N.
Published: July 2013

Pyromark 2500 is a silicone-based high-temperature paint that has been used on central receivers to increase solar absorptance. The radiative properties, aging, and selective absorber efficiency of Pyromark 2500 are presented in this paper for use as a baseline for comparison to high-temperature solar selective absorber coatings currently being developed. The solar absorptance ranged from ∼0.97 at near-normal incidence angles to ∼0.8 at glancing (80°) incidence angles, and the thermal emittance ranged from ∼0.8 at 100 °C to ∼0.9 at 1000 °C. After thermal aging at temperatures of ∼750 °C or higher, the solar absorptance decreased by several percentage points within a few days. It was postulated that the substrate may have contributed to a change in the crystal structure of the original coating at elevated temperatures.
A Contact-Aided Compliant Displacement-Delimited Gripper Manipulator
Authors: Saxena Anupam
Published: July 2013

A novel, monolithic, contact-aided, displacement-delimited gripper is presented. It is designed to employ contact interactions between its deforming members to delimit the output displacement such that excessive forces on the soft, fragile work-pieces are thwarted. The mechanism is appropriated using the topology, shape, and size optimization algorithm which, in addition to yielding structural details, also determines the interacting members and nature of contact. The symmetric halves of this design can be actuated independently thus rendering it the manipulative capabilities in addition to gripping. A cantilevered flexible “U” structure when introduced between the gripper ports of this mechanism can yield additional benefits in terms of reduced gripping forces. Macroscale Teflon prototype of the mechanism is tested on various work-pieces having different stiffness properties. Using experimentally acquired vision data, reaction loads on the work-pieces and gripper ports are estimated probabilistically by solving a Dirichlet problem for continua undergoing large deformation.
Microfluidic Valve Arrays in Thermoplastic Devices
Authors: Fan Z. Hugh , Gu Pan , Augustine Shancy , Liu Ke , Freitag Harvy , Nishida Toshikazu
Published: July 2013

Thermoplastics have been increasingly employed for microfluidic devices due to their manufacturability, low cost, and biocompatibility. A microfluidic device consists of a number of necessary building blocks, including microvalves that are often used for flow regulation. The state-of-the-art of the microfluidic valve technology is polydimethylsiloxane (PDMS)-based elastic membrane valve. This paper is to report the integration of the elastomer valve into a thermoplastic device. The valves were designed for a two-dimensional protein separation device, which was fabricated from cyclic olefin copolymers (COC). To realize the goal of integrating the elastomer-based valves in the device, the key challenge is to achieve strong bonding between COC and PDMS so that the device will not delaminate when a pressure is built up after the valves are closed. Microvalve arrays were fabricated in a COC/PDMS/COC device to facilitate the introduction of two types of separation media, without cross-contamination, into orthogonal channels in order to achieve two-dimensional separation. In addition, we studied thermal actuation in the microvalve, as an alternative to pneumatic actuation in the conventional PDMS-based elastomer valve. The thermally actuated valves can be self-contained, requiring less-bulky external accessories than pneumatically actuated valves.
Effectiveness Analysis of Non-Mechanical Micro-Valvular Conduit in Single Phase Flow
Authors: Lee Bong Joo , Culham J. R.
Published: July 2013

The non-mechanical valvular conduit, which uses no moving parts but instead relies on a complex geometry to regulate flow, is studied through a combination of numerical, computational and experimental methods. This study is based on using water as the fluid at standard state properties. A numerical model is developed to evaluate the effectiveness of the non-mechanical valve’s intricate geometry. Then computational simulations of the oscillating/pumping sequence of the valvular conduit are conducted to examine the effectiveness of the valve when placed in use for a diaphragm pump.

Results demonstrate that the non-mechanical valvular conduit can be an effective application for a diaphragm pump at the micro or macro-scale without requiring valvular mechanics. In computational simulations, when non-mechanical valves are positioned at both the inlet and exit of a diaphragm, the positive circulation of fluid is enhanced by 38% which is sufficient to meet the thermal dissipation requirements of an Intel Pentium D processor (i.e. 130 W). In addition, the experimental results in steady state condition demonstrated that the valvular design regulates the flow direction by producing diodicity (a measure of favorable flow direction) of 2.44.
Heat Pipe Performance in Microgravity: Lessons From the Constrained Vapor Bubble, CVB, Capillary Fin Experiment
Authors: Plawsky Joel L. , Wayner Peter C.
Published: July 2013

The Constrained Vapor Bubble (CVB) is a prototype for a wickless heat pipe and was developed into an experiment that was run in the microgravity environment of the International Space Station during 2010. Since the CVB is transparent, we can visualize the flow processes within the device in a way not possible before. Results from the experiment indicate that the CVB operates at higher pressures and temperatures in microgravity, a consequence of radiation being the only mechanism for removing heat from the device. The temperature profile data along the heat pipe and corresponding heat transfer calculations indicate that CVB performance is enhanced in the microgravity environment due to increased capillary flow even though heat transfer to the external environment is diminished by the absence of natural convection. Image data of the liquid profile in the grooves of the heat pipe indicate that the curvature gradient is considerably different from that on Earth and supports the conclusion that capillary flow and internal heat transfer is increased. Operations with the 20 mm version of the device allowed us to view explosive nucleation within the CVB upon device start-up. In this scenario, bubble nucleation occurred spontaneously and periodically at the hot end of the device. The nucleation process sent a shock wave through the pipe that collapsed the original bubble as a new vapor space was generated. The newly formed bubble returned to its original size, shape and location as heat loss from the CVB reestablished the original, pseudo-steady-state temperature and pressure profiles.
Two Phase Flow Patterns and Cooling Power of Mixed Refrigerant in Micro Cryogenic Coolers
Authors: Lewis Ryan , Schneider Hayley , Wang Yunda , Radebaugh Ray , Lee Y. C.
Published: July 2013

Micro cryogenic coolers (MCCs) operating in the Joule-Thomson cycle with mixed refrigerants offer an attractive way to decrease the size, cost, and power draw required for cryogenic cooling. Recent studies of MCCs with mixed refrigerants have, when employing pre-cooling, shown pulsating flow-rates and oscillating temperatures, which have been linked to the refrigerant flow regime in the MCC. In this study we investigate those flow regimes. Using a high-speed camera and optical microscopy, it is found that the pulsations in flow correspond to an abrupt switch from single-phase vapor flow to single-phase liquid flow, followed by 2-phase flow in the form of bubbles, liquid slugs, and liquid slug-annular rings. After this period of 2-phase flow, the refrigerant transitions back to single-phase vapor flow for the cycle to repeat. Under different pre-cooling temperatures, the mole fraction of the vapor-phase refrigerant, as measured by molar flow-rate, agrees reasonably well with the quality of the refrigerant at that temperature as calculated by an equation of state. The frequency of pulsation increases with liquid fraction in the refrigerant, and the volume of liquid in each pulse only weakly increases with increasing liquid fraction. The cooling power of the liquid-flow is up to a factor of 7 greater than that of the 2-phase flows and single-phase vapor flow.
Capillary Force-Driven Fluid Flow of a Wetting Liquid on a Surface With Multiple Parallel Open Microchannels
Authors: Chen Tailian
Published: July 2013

Fluid flow driven by the capillary force is omnipresent in nature and important in many engineering technologies. The focus of this work is capillary force-driven fluid flow of a wetting liquid in open microchannels when a liquid droplet is gently introduced to a metal surface on which multiple parallel microchannels with an open rectangular cross section are formed. It is found that, aided with a high-speed camera, the capillary-force driven fluid behavior consists of uni-directional spreading of the bulk droplet on the microchannel fins and liquid penetration into the microchannels. The kinetics of fluid flow due to the liquid penetration into the microchannels can be divided into three distinct stages: initial stage, transition stage, and Washburn stage; only in the Washburn stage, the flow has a penetration length-time dependence in proportion to square root of time as described by the Washburn’s equation. Comparison with liquid spreading on a plain surface having only one microchannel (the same geometry and size) revealed that the bulk droplet spreading on the microchannel fins, after elapse of the initial stage, has little effect on the fluid flow kinetics in the multiple microchannels. Some analytical results shed more insights into the capillary force-driven fluid flow in open microchannels.
Parameter Optimization for a Better Heat Distribution in a Microchannel Surface Cooler
Authors: Kamaruzaman Natrah , Brandner Juergen J.
Published: July 2013

Implementing short microchannels into a micro cooler device has been reported [1] as a way to obtain higher heat transfer rates compared to longer microchannel systems. In this publication simulation results obtained using Fluent software for two micro structure designs with symmetric passages containing two short microchannels are described. The first design shows a channel depth of 100 μm, the other one provides a channel depth of 50 μm. The purpose of this study is to define an optimized parameter set that will allow to optimize the heat distribution inside of microchannel devices. Polymer and copper has been selected as the test materials. As test fluid liquid water has been used. The results obtained with the simulations showed that the reduction of the depth of short microchannels while keeping the other dimensions constant increases the heat transfer performance. This is observed especially for a polymer device. The study of the influence of different materials such as polymer, copper, aluminum and steel has proven that the selection of highly conductive device material such as aluminum can enhance the heat transfer performance.
Numerical Investigation of Liquids Mixing in Pin-Finned Microchannels
Authors: Shafeie Haleh , Abouali Omid , Jafarpur Khosrow , Ahmadi Goodarz
Published: July 2013

In the present work, the performance of pin-finned microchannels as the micromixers is investigated. Different patterns for distribution of pin-fins were examined (staggered and oblique distribution of fins). A 3-D computational model was developed and the Navier-Stokes equations were solved and the corresponding flow fields were evaluated. The mass transport differential equation was also solved and the concentration of liquids in the mixture was evaluated. The results for the mixing efficiency were compared between the simple and pin-finned microchannels. The results suggest that the finned microchannels with staggered distribution of pins perform very well in mixing of liquids. The mixing efficiency reaches to 100 percent for the Reynolds numbers in which the mixing efficiency is less than 10 percent for the simple microchannels.
Photothermal Marangoni Convection for the Usage of Characterized Droplet Manipulation in Microfluidic Chip
Authors: Motosuke Masahiro , Hoshi Asami , Honami Shinji
Published: July 2013

Droplet-based microfluidics which involves discrete volumes with the use of immiscible phases enable controlled and rapid mixing inside the droplet and promoted reaction of reagents or cells. It can be operated as “digital fluidic platform.” Due to high surface area to volume ratio of transport phenomena in microscale, an interfacial behavior becomes more predominant than continuous-flow-based microfluidics. In this study, we have investigated an interfacial flow control based on local photothermal excitation of the interfacial tension gradient resulting in Marangoni convection for droplet manipulation in a microfluidic chip. The surface Marangoni flow occurs by the local thermal gradient induced by the localized light irradiation which is spatially characterized by a mask with a specific aperture geometry. In controlled droplet generation and manipulation, oil-in-water (O/W) system, oleic acid as the dispersed phase, were used in the present experiments. Droplets have volumes from 0.5 to 65 pL, corresponding to diameters from 10 to 50 μm. A microfluidic chip consists of two PDMS (polydimethylsiloxiane) channel layers fabricated using the softlithography. Spatially characterized heating is produced by a DPSS laser with a wavelength of 532 nanometers, a mask with aperture and a reduced-projection exposure optics. The light irradiation generates local temperature change in the continuous phase which can cause interfacial tension gradient when droplets come to the illuminated area. As a result, the droplet experiences a repulsion force from the illuminated area with high temperature because the liquid-liquid interface in this case has positive temperature dependence on the tension. The droplet can be trapped in the microchannel when U- or V-shaped light pattern is irradiated. When a light pattern with nozzle-like geometry is irradiated, droplets were focused toward the exit of the nozzle avoiding the irradiated area. The performances of the trapping and focusing of droplets due to the optically-induced interfacial flow were evaluated through behaviors of droplets with different sizes and light powers. The estimation of forces acting on a drop due to the photothermal Marangoni convection was also conducted.
Characterization of the Burkholderia thailandensis SOS Response by Using Whole-Transcriptome Shotgun Sequencing
Authors: Ulrich Ricky L. , DeShazer David , Kenny Tara A. , Ulrich Melanie P. , Moravusova Anna , Opperman Timothy , Bavari Sina , Bowlin Terry L. , Moir Donald T. , Panchal Rekha G.
Published: July 2013

The bacterial SOS response is a well-characterized regulatory network encoded by most prokaryotic bacterial species and is involved in DNA repair. In addition to nucleic acid repair, the SOS response is involved in pathogenicity, stress-induced mutagenesis, and the emergence and dissemination of antibiotic resistance. Using high-throughput sequencing technology (SOLiD RNA-Seq), we analyzed the
Burkholderia thailandensis
global SOS response to the fluoroquinolone antibiotic, ciprofloxacin (CIP), and the DNA-damaging chemical, mitomycin C (MMC). We demonstrate that a
B. thailandensis recA
mutant (RU0643) is ∼4-fold more sensitive to CIP in contrast to the parental strain
B. thailandensis
DW503. Our RNA-Seq results show that CIP and MMC treatment (
P
< 0.01) resulted in the differential expression of 344 genes in
B. thailandensis
and 210 genes in RU0643. Several genes associated with the SOS response were induced and include
lexA
,
uvrA
,
dnaE
,
dinB
,
recX
, and
recA
. At the genome-wide level, we found an overall decrease in gene expression, especially for genes involved in amino acid and carbohydrate transport and metabolism, following both CIP and MMC exposure. Interestingly, we observed the upregulation of several genes involved in bacterial motility and enhanced transcription of a
B. thailandensis
genomic island encoding a
Siphoviridae
bacteriophage designated ϕE264. Using
B. thailandensis
plaque assays and PCR with
B. mallei
ATCC 23344 as the host, we demonstrate that CIP and MMC exposure in
B. thailandensis
DW503 induces the transcription and translation of viable bacteriophage in a RecA-dependent manner. This is the first report of the SOS response in
Burkholderia
spp. to DNA-damaging agents. We have identified both common and unique adaptive responses of
B. thailandensis
to chemical stress and DNA damage.
Development of a Gene Knockout System Using Mobile Group II Introns (Targetron) and Genetic Disruption of Acid Production Pathways in Clostridium beijerinckii
Authors: Wang Yi , Li Xiangzhen , Milne Caroline B. , Janssen Holger , Lin Weiyin , Phan Gloria , Hu Huiying , Jin Yong-Su , Price Nathan D. , Blaschek Hans P.
Published: July 2013

Clostridium beijerinckii
is a well-known solvent-producing microorganism with great potential for biofuel and biochemical production. To better understand and improve the biochemical pathway to solvents, the development of genetic tools for engineering
C. beijerinckii
is highly desired. Based on mobile group II intron technology, a targetron gene knockout system was developed for
C. beijerinckii
in this study. This system was successfully employed to disrupt acid production pathways in
C. beijerinckii
, leading to
pta
(encoding phosphotransacetylase)- and
buk
(encoding butyrate kinase)-negative mutants. In addition to experimental characterization, the mutant phenotypes were analyzed in the context of our
C. beijerinckii
genome-scale model. Compared to those of the parental strain (
C. beijerinckii
8052), acetate production in the
pta
mutant was substantially reduced and butyrate production was remarkably increased, while solvent production was dependent on the growth medium. The
pta
mutant also produced much higher levels of lactate, suggesting that disrupting
pta
influenced the energy generation and electron flow pathways. In contrast, acetate and butyrate production in the
buk
mutant was generally similar to that of the wild type, but solvent production was consistently 20 to 30% higher and glucose consumption was more rapid and complete. Our results suggest that the acid and solvent production of
C. beijerinckii
can be effectively altered by disrupting the acid production pathways. As the gene disruption method developed in this study does not leave any antibiotic marker in a disrupted allele, multiple and high-throughput gene disruption is feasible for elucidating genotype and phenotype relationships in
C. beijerinckii
.
Distribution of Virulence Genes in Clinical and Environmental Vibrio cholerae Strains in Bangladesh
Authors: Hasan Nur A. , Ceccarelli Daniela , Grim Christopher J. , Taviani Elisa , Choi Jinna , Sadique Abdus , Alam Munirul , Siddique Abul K. , Sack R. Bradley , Huq Anwar , Colwell Rita R.
Published: July 2013

Vibrio cholerae
, an environmental organism, is a facultative human pathogen. Here, we report the virulence profiles, comprising 18 genetic markers, of 102 clinical and 692 environmental
V. cholerae
strains isolated in Bangladesh between March 2004 and January 2006, showing the variability of virulence determinants within the context of public health.
Transcriptome-Based Characterization of Interactions between Saccharomyces cerevisiae and Lactobacillus delbrueckii subsp. bulgaricus in Lactose-Grown Chemostat Cocultures
Authors: Mendes Filipa , Sieuwerts Sander , de Hulster Erik , Almering Marinka J. H. , Luttik Marijke A. H. , Pronk Jack T. , Smid Eddy J. , Bron Peter A. , Daran-Lapujade Pascale
Published: July 2013

Mixed populations of
Saccharomyces cerevisiae
yeasts and lactic acid bacteria occur in many dairy, food, and beverage fermentations, but knowledge about their interactions is incomplete. In the present study, interactions between
Saccharomyces cerevisiae
and
Lactobacillus delbrueckii
subsp.
bulgaricus
, two microorganisms that co-occur in kefir fermentations, were studied during anaerobic growth on lactose. By combining physiological and transcriptome analysis of the two strains in the cocultures, five mechanisms of interaction were identified. (i)
Lb. delbrueckii
subsp.
bulgaricus
hydrolyzes lactose, which cannot be metabolized by
S. cerevisiae
, to galactose and glucose. Subsequently, galactose, which cannot be metabolized by
Lb. delbrueckii
subsp.
bulgaricus
, is excreted and provides a carbon source for yeast. (ii) In pure cultures,
Lb. delbrueckii
subsp.
bulgaricus
grows only in the presence of increased CO
2
concentrations. In anaerobic mixed cultures, the yeast provides this CO
2
via alcoholic fermentation. (iii) Analysis of amino acid consumption from the defined medium indicated that
S. cerevisiae
supplied alanine to the bacterium. (iv) A mild but significant low-iron response in the yeast transcriptome, identified by DNA microarray analysis, was consistent with the chelation of iron by the lactate produced by
Lb. delbrueckii
subsp.
bulgaricus
. (v) Transcriptome analysis of
Lb. delbrueckii
subsp.
bulgaricus
in mixed cultures showed an overrepresentation of transcripts involved in lipid metabolism, suggesting either a competition of the two microorganisms for fatty acids or a response to the ethanol produced by
S. cerevisiae
. This study demonstrates that chemostat-based transcriptome analysis is a powerful tool to investigate microbial interactions in mixed populations.