bluuebunny/crossref_metadata_2025 huggingface dataset:
Early inflammation–associated factors blunt sterol regulatory element‐binding proteins‐1‐mediated lipogenesis in high‐fat diet‐fed APPSWE/PSEN1dE9 mouse model of Alzheimer's disease
Authors: Tang Ying , Peng Yunhua , Liu Jing , Shi Le , Wang Yongyao , Long Jiangang , Liu Jiankang
Published: November 2015

Alzheimer's disease (AD) patients have an increased incidence of Type 2 diabetes (T2D); however, the underlying mechanisms are not well understood. Since AD is considered a multifactorial disease that affects both the central nerves system and periphery and the dysregulation of hepatic lipid and glucose metabolism play critical roles in T2D, we, therefore, aim to explore the influence of AD genotype on the liver during the progress of high‐fat diet (HFD)‐induced T2D. Fourteen‐week‐old female APPSWE/PSEN1dE9 (AD) mice and age‐, gender‐matched wild‐type controls C57BL/6J (WT) mice were fed a HFD (45% kcal fat content) or a standard chow diet (chow, 12% kcal fat content) for 22 weeks. The effects of diet and genotype were analyzed. Mouse primary hepatocytes were used to decipher the underlying mechanisms. HFD induced significantly higher body weight gain, more severe hyperglycemia, glucose intolerance and hepatic insulin resistance in AD mice than in WT mice. However, AD mice showed reduced HFD‐induced hepatic steatosis, and SREBP‐1‐mediated lipogenic signaling was activated by HFD in WT mice but not in AD mice. In addition, 14‐week‐old AD mice exhibited higher expression of NF‐κB p65, p‐JNK and p‐p38MAPK, as well as higher hepatic and serum contents of IL‐6 and TNFα. In mouse primary hepatocyte cultures, IL‐6 and TNFα inhibited high‐glucose plus insulin‐induced activation of SREBP‐1‐mediated lipogenic signaling and biosynthesis of non‐esterified fatty acid and triglyceride. Early inflammation–associated factors most likely diminish HFD‐induced hepatic lipid deposition by inhibiting SREBP‐1‐mediated de novo lipogenesis, thus driving substrate flux to glucose production for hyperglycemia and hepatic insulin resistance in T2D development.

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Alzheimer's disease (AD) is a multifactorial disease affecting both central nerves system and periphery organs. Therefore, we explored the hepatic susceptibility to high‐fat diet (HFD) in AD mice. We found that AD mice were resistant to HFD‐induced hepatic fat accumulation in spite of more severe obesity, hyperglycemia, glucose intolerance and hepatic insulin resistance. Mechanistically, AD mice exhibited hepatic inflammation at an early stage, which inhibited sterol regulatory element‐binding proteins‐1 (SREBP‐1)‐mediated de novo lipogenesis, and most likely drive substrate flux to glucose production for hyperglycemia and hepatic insulin resistance.

Cover Image for this issue: doi: 10.1111/jnc.13306.
Metabolic, synaptic and behavioral impact of 5‐week chronic deep brain stimulation in hemiparkinsonian rats
Authors: Chassain Carine , Melon Christophe , Salin Pascal , Vitale Flora , Couraud Sébastien , Durif Franck , Kerkerian‐Le Goff Lydia , Gubellini Paolo
Published: November 2015

The long‐term effects and action mechanisms of subthalamic nucleus (STN) high‐frequency stimulation (HFS) for Parkinson's disease still remain poorly characterized, mainly due to the lack of experimental models relevant to clinical application. To address this issue, we performed a multilevel study in freely moving hemiparkinsonian rats undergoing 5‐week chronic STN HFS, using a portable constant‐current microstimulator. In vivo metabolic neuroimaging by 1H‐magnetic resonance spectroscopy (11.7 T) showed that STN HFS normalized the tissue levels of the neurotransmission‐related metabolites glutamate, glutamine and GABA in both the striatum and substantia nigra reticulata (SNr), which were significantly increased in hemiparkinsonian rats, but further decreased nigral GABA levels below control values; taurine levels, which were not affected in hemiparkinsonian rats, were significantly reduced. Slice electrophysiological recordings revealed that STN HFS was, uniquely among antiparkinsonian treatments, able to restore both forms of corticostriatal synaptic plasticity, i.e. long‐term depression and potentiation, which were impaired in hemiparkinsonian rats. Behavior analysis (staircase test) showed a progressive recovery of motor skill during the stimulation period. Altogether, these data show that chronic STN HFS efficiently counteracts metabolic and synaptic defects due to dopaminergic lesion in both the striatum and SNr. Comparison of chronic STN HFS with acute and subchronic treatment further suggests that the long‐term benefits of this treatment rely both on the maintenance of acute effects and on delayed actions on the basal ganglia network.

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We studied the effects of chronic (5 weeks) continuous subthalamic nucleus (STN) high‐frequency stimulation (HFS) in hemiparkinsonian rats. The levels of glutamate and GABA in the striatum () and substantia nigra reticulata (SNr) (), measured by in vivo proton magnetic resonance spectroscopy (1H‐MRS), were increased by 6‐hydroxydopamine (6‐OHDA) lesion, which also disrupted corticostriatal synaptic plasticity () and impaired forepaw skill () in the staircase test. Five‐week STN HFS normalized glutamate and GABA levels and restored both synaptic plasticity and motor function. A partial behavioral recovery was observed at 2‐week STN HFS.
Centrality of Body and Embodiment in Nursing Care: A Scoping Study of the Italian Literature
Authors: Marchetti Anna , Piredda Michela , De Marinis Maria Grazia
Published: November 2015

Purpose

Nursing has based its practical work on contact and a relationship with the patient's body and embodiment; however, the international theoretical and empirical researches on these concepts are still neglected. The purpose of this scoping study is to map the breadth and depth with which body and embodiment are addressed in the Italian nursing literature, identifying the key concepts and the main sources and types of evidence available.

Organizing Construct

Scoping study with qualitative content analysis. It was conducted in accordance with the framework outlined by Arksey and O'Malley and following the recommendations by Levac, Colquhoun, and O'Brien. The qualitative content analysis process was conducted according to Elo and Kyngäs. Lincoln and Guba's technique was followed to ensure trustworthiness.

Methods

Searches were conducted within seven electronic databases of peer‐reviewed literature, one electronic Italian database, six electronic database searches of grey literature, four free online nursing journals, four Internet search engines, and 10 key hard‐copy Italian nursing journals.

Findings

Through these searches, 2,536 records were identified, from which 18 were selected for the final review. Three generic categories emerged from qualitative content analysis: the conceptual category, the nursing care category, and the education category, each including eight, seven, and two subcategories, respectively.

Conclusions

The central nursing concepts of body and embodiment definitely require greater and more continuous efforts of theoretical study and empirical research within the nursing discipline, both in Italy and internationally.

Clinical Relevance

A greater awareness of body and embodiment should guide nursing practice in caring for and supporting patients and also guide approaches to teaching and learning. Moreover, body and embodiment are concepts firmly rooted in nursing practice, and they are also ripe for future research and able to generate more holistic and complex ways of understanding patients.
A comparative study of the effects of retinol and retinoic acid on histological, molecular, and clinical properties of human skin
Authors: Kong Rong , Cui Yilei , Fisher Gary J. , Wang Xiaojuan , Chen Yinbei , Schneider Louise M. , Majmudar Gopa
Published: November 2015

Background

All‐trans retinol, a precursor of retinoic acid, is an effective anti‐aging treatment widely used in skin care products. In comparison, topical retinoic acid is believed to provide even greater anti‐aging effects; however, there is limited research directly comparing the effects of retinol and retinoic acid on skin.

Objectives

In this study, we compare the effects of retinol and retinoic acid on skin structure and expression of skin function‐related genes and proteins. We also examine the effect of retinol treatment on skin appearance.

Methods

Skin histology was examined by H&E staining and in vivo confocal microscopy. Expression levels of skin genes and proteins were analyzed using RT‐PCR and immunohistochemistry. The efficacy of a retinol formulation in improving skin appearance was assessed using digital image‐based wrinkle analysis.

Results

Four weeks of retinoic acid and retinol treatments both increased epidermal thickness, and upregulated genes for collagen type 1 (COL1A1), and collagen type 3 (COL3A1) with corresponding increases in procollagen I and procollagen III protein expression. Facial image analysis showed a significant reduction in facial wrinkles following 12 weeks of retinol application.

Conclusions

The results of this study demonstrate that topical application of retinol significantly affects both cellular and molecular properties of the epidermis and dermis, as shown by skin biopsy and noninvasive imaging analyses. Although the magnitude tends to be smaller, retinol induces similar changes in skin histology, and gene and protein expression as compared to retinoic acid application. These results were confirmed by the significant facial anti‐aging effect observed in the retinol efficacy clinical study.
Immunoassay‐based Techniques for Early and Specific Detection of Latent Postharvest Anthracnose in Mango
Authors: Theerthagiri Anand , Govindasamy Senthilraja , Thiruvengadam Raguchander , Ramasamy Samiyappan
Published: November 2015

The postharvest anthracnose pathogen Colletotrichum gloeosporioides inciting latent or quiescent infection of mango was detected in early stages using immunoassay methods. Twenty‐five pathotypes isolated from different agroclimatic zones of Tamil Nadu, Karnataka and Pondicherry, India, revealed the variation in protein profile analysis (SDS‐PAGE). The polyclonal antibodies (PCA) were raised against the unfractioned mycelial protein (UMP) and a 40‐kDa polypeptide present in all pathotypes. Standardization of antigen and antiserum dilutions revealed that an antigen dilution of 1 : 200 (protein concentration of 20 μg/ml) and antiserum dilution of 1 : 100 (protein concentration of 40 μg/ml raised against UMP) and 1 : 200 (protein concentration of 20 μg/ml raised against 40 kDa polypeptide) was found to be optimum for the detection of anthracnose pathogen. Both antisera detected the C. gloeosporioides antigen in enzyme‐linked immunosorbent assays (ELISAs), dot immunobinding assays (DIBAs) and Western blots. The specificity in reaction was compared by isolating other Colletotrichum spp. from various hosts viz., C. lindemuthianum (beans), C. falcatum (sugarcane), C. musae (banana), C. capsici (chillies) and Botryodiplodia theobromae (mango). The antisera generated against UMP revealed the cross‐reaction with other host isolates and mango stem end rot pathogen (B. theobromae). The PCA raised against 40‐kDa polypeptide exhibited the specific reaction with C. gloeosporioides isolates in all the immunoassay techniques. By utilizing both PCA, the presence of latent infection was observed in healthy‐looking leaves, flowers and fruits in orchard conditions. The fruit tissues recorded high absorbance values followed by flowers and leaves in all the detection methods. The ELISA technique was also useful in assessing the pathogen inoculum at various biocontrol formulations sprayed mango trees under field conditions. The fluorescent pseudomonad strains mixture (KFP1 + FP7) amended with chitin sprayed at 30‐day intervals revealed the significant reduction in pathogen load than other formulations and unsprayed control.
The Periphery Strikes Back? The Subtlety of Latin American Power in the United States
Authors: Rodriguez‐Medina Leandro , Emerson R. Guy
Published: November 2015

In this article, we propose the concepts of “generalized” and “specialized” soft power through an analysis of the effects of Latino power in the United States. By focusing on demographic features, mass media, education, science and technology, and business, we attempt to provide a snapshot of the subtlety of Latino power in terms of flows and degrees of penetration within the U.S. landscape. We conclude by pointing out the main differences between these two theoretic concepts to deepen the understanding of the ways that peripheral regions might exert power on powerful countries.
Cultural Aspects of the Japanese Business Model Applied in Mexico
Authors: Laborde Adolfo
Published: November 2015

This article analyzes how Japanese trading companies (Sogo Sosha, in Japanese) have penetrated international markets, especially Mexico, thanks to their organizational and operating efficiency. It focuses on how these companies operate and presents a model for small‐ and medium‐sized enterprises to follow that consists of continuous improvement through corporate diagnostic processes. Officials from the Japanese International Cooperation Agency prepared this model to increase the competitiveness of small‐ and medium‐sized businesses. The conclusion is that if these businesses in Mexico made the most of the method, they could increase their participation in international markets.
Latent developmental and evolutionary shapes embedded within the grapevine leaf
Authors: Chitwood Daniel H. , Klein Laura L. , O'Hanlon Regan , Chacko Steven , Greg Matthew , Kitchen Cassandra , Miller Allison J. , Londo Jason P.
Published: November 2015

Across plants, leaves exhibit profound diversity in shape. As a single leaf expands, its shape is in constant flux. Plants may also produce leaves with different shapes at successive nodes. In addition, leaf shape varies among individuals, populations and species as a result of evolutionary processes and environmental influences.

Because leaf shape can vary in many different ways, theoretically, the effects of distinct developmental and evolutionary processes are separable, even within the shape of a single leaf. Here, we measured the shapes of > 3200 leaves representing > 270 vines from wild relatives of domesticated grape (Vitis spp.) to determine whether leaf shapes attributable to genetics and development are separable from each other.

We isolated latent shapes (multivariate signatures that vary independently from each other) embedded within the overall shape of leaves. These latent shapes can predict developmental stages independent from species identity and vice versa. Shapes predictive of development were then used to stage leaves from 1200 varieties of domesticated grape (Vitis vinifera), revealing that changes in timing underlie leaf shape diversity.

Our results indicate that distinct latent shapes combine to produce a composite morphology in leaves, and that developmental and evolutionary contributions to shape vary independently from each other.
Secretory component mediates Candida albicans binding to epithelial cells
Authors: van der Wielen PA , Holmes AR , Cannon RD
Published: November 2015

Objectives

Candida albicans attaches to oral surfaces via a number of mechanisms including adherence mediated by salivary components adsorbed to the C. albicans cell surface. Our goal was to identify the salivary molecules involved.

Materials and Methods

Biotinylated salivary polypeptides that were bound by C. albicans were detected in extracts from washed, saliva‐treated yeast cells by polyacrylamide gel electrophoresis and electroblot or immunoblot transfer analysis and purified by electroelution. Purified material was tested for the ability to promote the adherence of radiolabelled C. albicans yeast cells to cultured epithelial monolayers.

Results

Three of the polypeptides bound by C. albicans cells were identified as components of secretory IgA, including secretory component. Using non‐denaturing polyacrylamide gel electrophoresis, we demonstrated that secretory component could be detected in its free form in saliva, and was bound by yeast cells. Secretory component which was purified by electroelution from non‐denaturing PAGE‐separated saliva, without detectable complete IgA, promoted adherence of yeast cells to cultured epithelial monolayers in a dose‐dependent fashion.

Conclusion

These results indicate that despite the inhibitory effect on adherence of IgA specific to C. albicans, IgA components, in particular secretory component, also promote binding to cultured epithelial monolayers.
Eucalyptus hairy roots, a fast, efficient and versatile tool to explore function and expression of genes involved in wood formation
Authors: Plasencia Anna , Soler Marçal , Dupas Annabelle , Ladouce Nathalie , Silva‐Martins Guilherme , Martinez Yves , Lapierre Catherine , Franche Claudine , Truchet Isabelle , Grima‐Pettenati Jacqueline
Published: November 2015

Eucalyptus are of tremendous economic importance being the most planted hardwoods worldwide for pulp and paper, timber and bioenergy. The recent release of the Eucalyptus grandis genome sequence pointed out many new candidate genes potentially involved in secondary growth, wood formation or lineage‐specific biosynthetic pathways. Their functional characterization is, however, hindered by the tedious, time‐consuming and inefficient transformation systems available hitherto for eucalypts. To overcome this limitation, we developed a fast, reliable and efficient protocol to obtain and easily detect co‐transformed E. grandis hairy roots using fluorescent markers, with an average efficiency of 62%. We set up conditions both to cultivate excised roots in vitro and to harden composite plants and verified that hairy root morphology and vascular system anatomy were similar to wild‐type ones. We further demonstrated that co‐transformed hairy roots are suitable for medium‐throughput functional studies enabling, for instance, protein subcellular localization, gene expression patterns through RT‐qPCR and promoter expression, as well as the modulation of endogenous gene expression. Down‐regulation of the Eucalyptus cinnamoyl‐CoA reductase1 (EgCCR1) gene, encoding a key enzyme in lignin biosynthesis, led to transgenic roots with reduced lignin levels and thinner cell walls. This gene was used as a proof of concept to demonstrate that the function of genes involved in secondary cell wall biosynthesis and wood formation can be elucidated in transgenic hairy roots using histochemical, transcriptomic and biochemical approaches. The method described here is timely because it will accelerate gene mining of the genome for both basic research and industry purposes.
Human immunodeficiency virus and risk of porphyria cutanea tarda: a possible association examined in a large hospital
Authors: Aguilera Paula , Laguno Montserrat , To‐Figueras Jordi
Published: November 2015

Background

Human immunodeficiency virus (HIV) infection has been reported to be a risk factor for porphyria cutanea tarda (PCT).

Purpose

To assess the strength of the association between HIV infection and PCT in a large hospital setting.

Methods

All patients (N = 210) diagnosed of PCT between 1990 and 2014 were retrospectively investigated for HIV infection and co‐precipitating factors. High‐performance liquid chromatography was used to assess the appearance of pre‐PCT urinary porphyrin abnormalities among a group (N = 22) of HIV‐infected patients without PCT using the urine of patients co‐infected with hepatitis C virus (HCV) without PCT for comparison.

Results

Twenty‐six HIV‐infected patients (19 males and seven females) were diagnosed of PCT. During the same interval of time, ~8000 different patients infected with HIV were attended in the hospital of infectious diseases department. Examination of risk factors showed that 25 out of 26 of the PCT patients with HIV were co‐infected with HCV. No chromatographic abnormalities were found in the urine of non‐PCT‐HIV‐infected patients, whereas 39% co‐infected patients showed urinary porphyrin abnormalities.

Conclusions

In our large hospital series, the appearance of PCT among HIV‐infected patients is low (<1%) and most present co‐infection with HCV. Therefore, in most HIV‐infected patients with PCT, hepatitis C and not HIV may induce uroporphyrinogen decarboxylase deficiency.
Conditioned medium from human bone marrow‐derived mesenchymal stem cells promotes skin moisturization and effacement of wrinkles in UVB‐irradiated SKH‐1 hairless mice
Authors: Kwon Tae‐Rin , Oh Chang Taek , Choi Eun Ja , Kim Soon Re , Jang Yu‐Jin , Ko Eun Jung , Yoo Kwang Ho , Kim Beom Joon
Published: November 2015

Background

Mesenchymal stem cells (MSCs) are promising therapeutic agents for various diseases.

Aims

To investigate the effects of conditioned medium from human bone marrow‐derived mesenchymal stem cells (MSC‐CdM) on pro‐collagen production and wrinkle formation, we performed in vitro and in vivo experiments.

Methods

We assessed the effects of MSC‐CdM on proliferation and photo‐aging in human dermal fibroblasts after UVB exposure using enzyme activity assays for collagen type I secretion and MMP‐1. To determine the effect of topically applied MSC‐CdM on wrinkle formation, MSC‐CdM (1% and 10%) and vehicle (propylene glycol: ethanol, 7 : 3) were applied to the dorsal skin of UVB‐irradiated hairless mice for 8 weeks. We examined the effects on wrinkle formation by assessing visual skin grading, replica, tape stripping, transepidermal water loss (TEWL), and skin hydration measurement. We also examined histology of the lesions using hematoxylin–eosin, Masson's trichrome, and immunohistochemical staining.

Results

MSC‐CdM markedly reduced UV‐induced matrix metalloproteinase‐1 expression and increased pro‐collagen synthesis in a dose‐dependent manner. Our findings suggest that MSC‐CdM induces repair of dermal damage and effacement of wrinkles on UVB‐irradiated hairless mice through protective effect of hydration.

Conclusion

These results support an anti‐wrinkle effect of MSC‐CdM that involves increased collagen synthesis and suggest that MSC‐CdM might be a potential candidate for preventing UV‐induced skin damage.
The role of infection and sepsis in the Brazilian Network for Surveillance of Severe Maternal Morbidity
Authors: Pfitscher L. C. , Cecatti J. G. , Haddad S. M. , Parpinelli M. A. , Souza J. P. , Quintana S. M. , Surita F. G. , Costa M. L. ,   the Brazilian Network for Surveillance of Severe Maternal Morbidity Study Group
Published: November 2015

Objective

To identify the burden of severe infection within the Brazilian Network for Surveillance of Severe Maternal Morbidity and factors associated with worse maternal outcomes.

Methods

This was a multicentre cross‐sectional study involving 27 referral maternity hospitals in Brazil. WHO′s standardised criteria for potentially life‐threatening conditions and maternal near miss were used to identify cases through prospective surveillance and the main cause of morbidity was identified as infection or other causes (hypertension, haemorrhage or clinical/surgical). Complications due to infection were compared to complications due to the remaining causes of morbidity. Factors associated with a severe maternal outcome were assessed for the cases of infection.

Results

A total of 502 (5.3%) cases of maternal morbidity were associated with severe infection vs. 9053 cases (94.7%) with other causes. Considering increased severity of cases, infection was responsible for one‐fourth of all maternal near miss (23.6%) and nearly half (46.4%) of maternal deaths, with a maternal near miss to maternal death ratio three times (2.8:1) that of cases without infection (7.8:1) and a high mortality index (26.3%). Within cases of infection, substandard care was present in over one half of the severe maternal outcome cases. Factors independently associated with worse maternal outcomes were HIV/AIDS, hysterectomy, prolonged hospitalisation, intensive care admission and delays in medical care.

Conclusions

Infection is an alarming cause of maternal morbidity and mortality and timely diagnosis and adequate management are key to improving outcomes during pregnancy. Delays should be addressed, risk factors identified, and specific protocols of surveillance and care developed for use during pregnancy.
MYBD employed by HY5 increases anthocyanin accumulation via repression of MYBL2 in Arabidopsis
Authors: Nguyen Nguyen Hoai , Jeong Chan Young , Kang Geun‐Ho , Yoo Sang‐Dong , Hong Suk‐Whan , Lee Hojoung
Published: November 2015

Photomorphogenesis is an essential program in plant development. This process is effected by the balanced cooperation of many factors under light and dark conditions. In a previous study, we showed that MYB hypocotyl elongation‐related (MYBH) is involved in cell elongation. To expand our understanding of MYBH function, we performed a yeast two‐hybrid assay and identified an MYB‐like Domain transcription factor (MYBD). In this study, we investigated the function of MYBD, which is an MYBH homolog involved in anthocyanin accumulation. MYBD expression increased in response to light or cytokinin, and MYBD enhanced anthocyanin biosynthesis via repression of MYBL2, which encodes a transcription factor that has a negative effect on this process. In addition, MYBD binding in vivo to the MYBL2 promoter and the lower level of histone H3K9 acetylation at the upstream region of MYBL2 in MYBD over‐expressing plants in comparison with wild‐type plants imply that MYBD represses MYBL2 expression via an epigenetic mechanism. HY5 directly binds to the MYBD promoter, which indicates that MYBD acts on HY5‐downstream in light‐ or cytokinin‐triggered signaling pathways, leading to anthocyanin accumulation. Our results suggest that, although MYBD and MYBH are homologs, they act in opposite ways during plant photomorphogenesis, and these functions should be examined in further studies.
Lattice Boltzmann Simulation of Rarefied Gas Flow Along Moving Rigid Objects in Micro-Cavities
Authors: Yang Weilin , Li Hongxia , Zhang TieJun , Elfadel Ibrahim M.
Published: November 2015

Rarefied gas flow plays an important role in the design and performance analysis of micro-electro-mechanical systems (MEMS) under high-vacuum conditions. The rarefaction can be evaluated by the Knudsen number (Kn), which is the ratio of the molecular mean free path length and the characteristic length. In micro systems, the rarefied gas flow usually stays in the slip- and transition-flow regions (10−3 < Kn < 10), and may even go into the free molecular flow region (Kn > 10). As a result, conventional design tools based on continuum Navier-Stokes equation solvers are not applicable to analyzing rarefaction phenomena in MEMS under vacuum conditions. In this paper, we investigate the rarefied gas flow by using the lattice Boltzmann method (LBM), which is suitable for mesoscopic fluid simulation. The gas pressure determines the mean free path length and Kn, which further influences the relaxation time in the collision procedure of LBM. Here, we focus on the problem of squeezed film damping caused by an oscillating rigid object in a cavity. We propose an improved LBM with an immersed boundary approach, where an adjustable force term is used to quantify the interaction between the moving object and adjacent fluid, and further determines the slip velocity. With the proposed approach, the rarefied gas flow in MEMS with squeezed film damping is characterized. Different factors that affect the damping coefficient, such as pressure of gas and frequency of oscillation, are investigated in our simulation studies.
Characterisation of a Novel Pulsating Heat Pipe Cooler for Power Electronics at Extreme Ambient Temperatures
Authors: Torresin Daniele , Habert Mathieu , Mounier Violette , Agostini Francesco , Agostini Bruno
Published: November 2015

A compact and low cost pulsating heat pipe cooler (PHP) based on automotive technology is presented. This technology uses numerous aluminium MultiPort Extruded (MPE) tubes with capillary sized channels disposed in parallel to achieve the desired compactness. The sub-channels of the MPEs are connected in a serpentine manner by means of fluid distribution elements integrated in the evaporator and condenser manifolds. This configuration enables the oscillation of liquid slugs and elongated bubbles between the evaporator and the condenser areas.

In the present paper the experimental results of an open loop type PHP with refrigerants fluids R134a and R245fa are presented. Tests have been carried out for air temperatures ranging between −60 and 60 °C at a fixed air flow rate of 480 m3/h and heat loads from 3 to 13 W/cm2. The experimental results show the different thermo-physical properties effect of the two tested fluids on the cooler performances: R134a is more adapted to low saturation temperature than R245fa and the contrary has been observed at high saturation temperatures. This is due to the fact that R245fa reaches its viscous limit at low temperatures while at high temperatures R134a reaches its critical temperature.
A Study on Heat Sink Performance Using V-Shaped Cannelure Structure Fin
Authors: Huang Po-Sheng , Wang Chi-Chuan
Published: November 2015

The present study proposed a V-shape cannelure structure applicable for electronic cooling thermal module. Initially, simulations are made to find out the best configurations, followed by an actual implementation and verification. From the experimental verification, it is found that the proposed modified thermal module can appreciably reduce the heat sink volume (up to 30%) and still maintain a lower base temperature than the original plain fin design. Yet it is found that an overall 16% improvement of the heat transfer performance can be achieved.
Condensation Heat Transfer Characteristics on the Outside of Horizontal Smooth, Herringbone and Enhanced Surface 1EHT Tubes
Authors: Zhou Xiao-peng , Kukulka David J. , Li Jing , Sun Jian-Jun , Li Wei
Published: November 2015

Heat transfer enhancement plays an important role in improving energy efficiency and developing high performance thermal systems. Phase-change heat transfer processes take place in thermal systems; typically heat transfer enhanced tubes are used in these systems and they are designed to increase heat transfer coefficients in evaporation and condensation. Enhanced heat transfer tubes are widely used in refrigeration and air-conditioning applications in order to reduce cost and create a smaller footprint of the application.

Microfins, roughness and dimples are often incorporated into the inner surface of tubes in order to enhance heat transfer performance. Under many conditions, enhanced surface tubes can recover more energy and provide the opportunity to advance the design of many heat transfer products.

Convective condensation heat transfer and pressure loss characteristics were investigated for R410A on the outside of: (i) a smooth tube (outer diameter 12.7 mm); (ii) an external herringbone tube (fin root diameter 12.7 mm); and (iii) the 1EHT tube (outer diameter 12.7 mm) for very low mass fluxes. Data was obtained for values of mass flux ranging from 8 to 50 kg/(m2 s); at a saturation temperature of 318 K; with an inlet quality of 0.8 (±0.05) and an outlet quality of 0.1 (±0.05). In a comparison of heat transfer at a low mass flux, both the 1EHT tube and the herringbone tube did not perform as well as the smooth tube. And it’s difficult to analyze the reason for this strange phenomenon.
High Flux Microscale Solar Thermal Receiver for Supercritical Carbon Dioxide Cycles
Authors: L’Estrange Thomas , Truong Eric , Rymal Charles , Rasouli Erfan , Narayanan Vinod , Apte Sourabh , Drost Kevin
Published: November 2015

Characterization of a microchannel solar thermal receiver for a supercritical carbon dioxide (sCO2) is presented. The receiver design is based on conjugate computational fluid dynamics and heat transfer simulations as well as thermo-mechanical stress analysis. Two receivers are fabricated and experimentally characterized — a parallel microchannel design and a microscale pin fin array design. Lab-scale experiments have been used to demonstrate the receiver integrity at the design pressure of 125 bar at 750°C surface temperature. A concentrated solar simulator was designed and assembled to characterize the thermal performance of the lab scale receiver test articles. Results indicate that, for a fixed exit fluid temperature of 650°C, increase in incident heat flux results in an increase in receiver and thermal efficiency. At a fixed heat flux, efficiency decreased with an increase in receiver surface temperature. The ability to absorb flux of up to 100 W/cm2 at thermal efficiency in excess of 90 percent and exit fluid temperature of 650°C using the microchannel receiver is demonstrated. Pressure drop for the pin array at the maximum flow rate for heat transfer experiments is less than 0.64 percent of line pressure.
Numerical Analysis of Heat Transfer Characteristics for Supercritical Aviation Kerosene
Authors: Song Yachao , Ma Danjiao , Zhang Jingzhi , Chen Jing-xiang , Chen Songze , Li Wei
Published: November 2015

With the physical property changing dramatically, the supercritical aviation kerosene obtains unique heat transfer characteristics. In this way, it is difficult to investigate the heat transfer characteristics by normal experiment and therefore we resort to numerical analysis to address the scientific questions in this study. The project is proposed to demystify the heat transfer characteristics of supercritical aviation kerosene with CFD in 4mm inside diameter vertical circular tubes. Under the conditions of different pressures (3.5MPa-5MPa), the physical properties of the fluid are expressed in linear poly-nominal fitting including density, isobaric specific heat, thermal conductivity and viscosity. With the guidance of CFD, we analyze how the heat transfer characteristics can be affected by the value of temperature, pressure, heat flux mass velocity and so on. The result indicates: (1) In primary heating process, convective heat transfer is enhanced significantly. (2) When wall temperature surpasses the critical temperature, heat transfer can be deteriorated. (3) When the temperature continues to go up, the convective heat transfer coefficient will rise greatly again. Furthermore, the project has also compared the numerical analysis result with experimental result, which shows good agreement with each other. Hence, the validation of numerical analysis of supercritical fluid is well recognized.
Heat Transfer in Liquid-Liquid Taylor Flow in a Mini-Scale Tube With Constant Wall Temperature
Authors: Adrugi W. M. , Muzychka Y. S. , Pope K.
Published: November 2015

In this paper, heat transfer enhancement using liquid-liquid Taylor flow is examined. The experiments are conducted in mini-scale tubes with constant wall temperature. The segmented flow is created using several fractions of low viscosity silicone oil (1 cSt) and water for a wide range of flow rates and segment lengths. The variety of liquids and flow rates change the Prandtl, Reynolds, and capillary numbers. The dimensionless mean wall flux and the dimensionless thermal flow length are used to analyze the experimental heat transfer data. The comparison shows the heat transfer rate for Taylor flow is higher than in single-phase flow. The heat transfer enhancement occurs due to internal circulation in the fluid segments.
Removal of Shape Deformation in the Free Energy Based Lattice Boltzmann Method for Large Density Ratio
Authors: Gong Jia-ming , Oshima Nobuyuki , Tabe Yutaka
Published: November 2015

The free energy based lattice Boltzmann method (LBM) for two-phase flow with large density ratio is used to simulate droplet dynamics in the polymer electrolyte fuel cell (PEFC). The shape deformation of a static water droplet in the gas channel occurred in the simulations was eliminated. In this LBM model, two types of staggered grids which respectively make use of the velocity components from the orthogonal and diagonal directions are blended to calculate the hydrodynamic pressure from the Poisson equation, with the successive over-relaxation method (SOR). It is found that the simulated water droplet shape is determined by both the blending factor of the two types of staggered grids and the radius length. The appropriate blending factor for each radius length is summarized to optimize the simulation. The dependence of shape deformation on the blending factor and the radius length is further validated while considering the wettability effect of the solid wall of the gas channel. It is proved that the summarized appropriate blending factors are still practical when the concept of equivalent radius length is adopted.
Transient Evolution of Heat Transfer Performance During Flow Boiling in a Microchannel
Authors: Jagirdar Mrinal , Lee Poh Seng
Published: November 2015

There is a dearth of understanding about the underlying mechanisms of heat transfer during various flow boiling regimes prevalent during flow boiling in microchannels. In this paper, high frequency temperature data and flow visualization have been captured simultaneously to understand the heat transfer mechanisms. Experiments were performed on a single microchannel with height, width and length of 0.42 mm, 2.54 mm and 25.4 mm respectively. The working fluid was deionized, de-gassed water. The tested heat flux and mass flux were 28 W/cm2 and 180.1 kg/m2s respectively. The flow boiling regime observed was slug flow. Temperature captured was below the wetted surface and hence Inverse Heat Conduction Problem (IHCP) solution methodology had to be used. Its efficacy was first tested and was found to be reasonably good. Transient wetted surface heat flux, temperature and heat transfer coefficient were calculated using this methodology and were then correlated with the visual data. Depending on the flow boiling phenomena, there were significant variations in heat transfer with time. Several insights into the heat transfer mechanisms have been presented.
Determining the Compressive Behavior of an Ultra-Thin Elastoviscoplastic Membrane Used in Sealing a Microchannel Hemodialyser
Authors: McNeff Patrick S. , Paul Brian K.
Published: November 2015

In past efforts, the conditions were determined for the hermetic sealing of a microchannel hemodialyser produced by pressing a hot-embossed polycarbonate microchannel lamina containing sealing bosses, against a 25 μm thick elastoviscoplastic hemodialysis membrane. In this paper, a procedure is developed for quantifying the compressive mechanical behavior of the membrane during loading. An energy balance, of the work of clamping to the strain energy within the membrane, is used to derive a model for predicting the force required to seal the membrane. The force model is used to predict the force required to press a boss a certain distance into the membrane, providing validation of the procedure for measuring the compressive properties of ultra-thin elastoviscoplastic membranes.
Electrowetting on Dielectric (EWOD) Assisted Droplet Desiccation
Authors: Greyson Marcette , Dunning Peter D. , Schertzer Michael J.
Published: November 2015

Lab-on-a-chip (LOAC) devices are emerging technologies that aim to perform all of the laboratory functions of traditional diagnostic tests on single microchips. Microarrays are one promising type of LOAC device that consist of an array of droplets for testing tens to thousands of samples simultaneously. Microarrays are commonly used in gene sequencing, pathogen detection, determining microbial resistances, and conducting enzyme-linked immunosorbent assays (ELISAs). As droplets in these arrays dry, the majority of material within the droplet is deposited around the periphery. This phenomenon is referred to as the coffee stain effect. The non-uniform depositions left by this effect can result in variation of fluorescence intensity measurements in automated vision systems. A means of producing more uniform particle depositions for the microscopy analysis would allow for more accurate test results.

One promising method for suppression of the coffee stain effect involves the use of electrowetting on dielectric (EWOD). EWOD devices apply an electrokinetic force at the three-phase contact line to manipulate the shape of a droplet interface. The Mugele group has already begun investigating EWOD’s effects on the coffee stain effect and found that an AC voltage applied to droplets on EWOD devices can suppress the coffee stain effect and produce smaller, more uniform droplet deposition patterns.

This work presents (i) a method to characterize the deposition pattern left by a desiccated droplet as a function of radial position and (ii) a discussion of the microfabrication technique used to create devices to perform EWOD assisted desiccation for both AC and DC voltages.
Numerical Model of Template-Based Chemical Vapor Deposition Processes to Manufacture Carbon Nanotubes for Biological Devices
Authors: Vahedein Yashar Seyed , Schrlau Michael G.
Published: November 2015

Carbon nanotubes (CNTs) hold significant promise in the fields of efficient drug delivery and bio-sensing for disease treatment because of their unique properties. In our lab, single and arrayed CNT-tipped devices are manufactured by deposition of carbon on the heated surfaces of templates using chemical vapor deposition (Template-Based Chemical Vapor Deposition, TB-CVD). Experimental results show CNT formation in templates is controlled by TB-CVD process parameters such as flow rate and temperature. However, there is a need for a more comprehensive and low cost way to characterize the flow in the furnace in order to understand how process parameters may affect CNT formation. In this report, 2D and 3D numerical models with Quadrilateral grids were developed using computational fluid dynamic (CFD) commercial codes. Velocity patterns and flow regimes in the tube were compared with experimental data. In addition, statistical techniques were employed to study temperature profiles and velocity patterns in the furnace as a function of flow rate. The outcome of this work will help to elucidate the TB-CVD process and facilitate the efficient manufacture of carbon nanostructures from a variety of templates. The results are broadly applicable to the manufacturing of CNTs and other nanostructured devices used in energy and biomedical fields, including CNT-based devices used in biological applications.
Effect of Hydrodynamic Slippage on Oscillating Electroosmotic Flows in Infinitely Extended Microcapillary
Authors: Rojas Guillermo , Bautista Oscar E. , Mendez Federico
Published: November 2015

In this work we conduct a numerical analysis of the time periodic electroosmotic flow in a cylindrical microcapillary, whose wall is considered hydrophobic. The fluid motion is driven by the sudden imposition of a time-dependent electric field. The electrical potential is obtained by solving the nonlinear Poisson-Boltzmann equation for high zeta potential, under the assumption that the electrokinetic potential is not affected by the oscillatory external field. In addition, we neglect the channel entry and exit effects, in such manner that the flow is fully developed. The governing equations are nondimensionalized, and the solution is obtained as a function of three dimensionless parameters: the ratio of the Navier slip length to the radius of the microcapillary, δ; Rω, which is the dimensionless frequency for the flow or Strouhal number and measures the competition between the diffusion time to the time scale associated to the frequency of the oscillatory electric field; and κ, which represents the ratio of the radius of the microcapillary to the Debye length. The principal results show that using slippage, the bulk velocity increases for increasing values of δ. For the values of the dimensionless parameters used in this analysis, by using hydrophobic walls, the bulk velocity can be increased in about 20% in comparison with the case of no-slip boundary condition. On the other hand, the dimensionless frequency for the flow or Strouhal number plays a fundamental role in determining the motion of the fluid. For Rω ≪ 1, the dissipation is found in resonance with the frequency of the oscillatory electric field. For Rω ≫ 1, the dissipation is not in phase with the frequency and, therefore, the velocity in the center of the microcapillary, in some cases, is almost null, and the maximum value of the velocity is near to the microcapillary wall.
A Computational and Experimental Study of Metal and Covalent Organic Frameworks Used in Adsorption Cooling
Authors: Jenks J. J. , Tegrotenhuis Ward , Motkuri Radha K. , Paul Brian K. , McGrail B. Peter
Published: November 2015

Metal-organic frameworks (MOFs) have recently attracted enormous interest over the past few years due to their potential applications in energy storage and gas separation. However, there have been few reports on MOFs for adsorption cooling applications. Adsorption cooling technology is an established alternative to mechanical vapor compression refrigeration systems. Adsorption cooling is an excellent alternative in industrial environments where waste heat is available. Applications also include hybrid systems, refrigeration, powerplant dry cooling, cryogenics, vehicular systems and building HVAC. Adsorption based cooling and refrigeration systems have several advantages including few moving parts and negligible power consumption. Key disadvantages include large thermal mass, bulkiness, complex controls, and low COP (0.2–0.5). We explored the use of metal organic frameworks that have very high mass loading and relatively low heats of adsorption, with certain combinations of refrigerants to demonstrate a new type of highly efficient adsorption chiller. An adsorption chiller based on MOFs suggests that a thermally-driven COP>1 may be possible with these materials, which would represent a fundamental breakthrough in performance of adsorption chiller technology. Computational fluid dynamics combined with a system level lumped-parameter model have been used to project size and performance for chillers with a cooling capacity ranging from a few kW to several thousand kW. In addition, a cost model has been developed to project manufactured cost of entire systems. These systems rely on stacked micro/mini-scale architectures to enhance heat and mass transfer. Presented herein are computational and experimental results for hydrophyilic MOFs, fluorophilic MOFs and also flourophilic Covalent-organic frameworks (COFs).
On the Lifetime of Non-Coalescent Levitated Droplets
Authors: Davanlou Ashkan , Kumar Ranganathan
Published: November 2015

It is shown that a droplet will levitate over the liquid surface for 50–700 ms when released from a critical height 1.5–4 times the droplet diameter. While releasing a droplet out of this range will lead to direct submersion. Additionally, it is shown that by applying a temperature difference between the liquid pool and droplet it is possible to elongate the levitation time of that droplet as it pulls the surrounding air molecules between the drop and the pool surface. Lastly, the thickness of the air gap is calculated theoretically for a range of temperatures and compared with experiments. Surprisingly, larger temperature difference between droplet and surface causes an increase in the thickness of the air gap. It is also found that the size of droplet and type of fluid can significantly affect the lifetime of non-coalescent drops.
Flux dependent Sb-incorporation during molecular beam epitaxy of InAsSb
Authors: Sarney Wendy L. , Svensson Stefan P.
Published: November 2015

A strong dependence of the InAsSb composition on the group III flux during molecular beam epitaxy growth has been observed and quantified. Analogous to group III alloying, the Sb concentration is expressed as the ratio of the Sb to the sum of the group V fluxes, modified by an empirical interaction parameter that is strongly dependent on the In flux. A well-behaved quadratic polynomial characterizes this parameter. By extrapolating the growth rate to zero, important information about the Sb-As exchange reaction of a static surface can be extracted and the required Sb/As flux ratio to maintain stoichiometry is predicted.