bluuebunny/crossref_metadata_2025 huggingface dataset:
The First ‘European’ Writing: Redefining the Archanes Script
Authors: Decorte Roeland P.‐J. E.
Published: November 2018

This paper investigates a series of glyptic inscriptions attested on Crete at the end of the third and beginning of the second millennium BC, collectively referred to as the ‘Archanes Script’. These minute engravings are considered to represent the earliest appearance of writing west of Egypt, and the first ‘true’ writing in the Aegean. Though mentioned in passing in almost every study of Bronze Age Aegean writing, few scholars have ever offered a definition of what exactly they consider the ‘Archanes Script’ to be. No work or scholarly consensus exists delineating which signs constitute its signary, or even which documents comprise its corpus. Study of the seals as objects in their own right, examining script signs alongside associated iconography, material qualities and form, has been rare. This paper offers the first complete overview and redefinition of the Archanes Script since its discovery in the 1960s and initial definition by Paul Yule in 1980.
Glucosylation of (Z)‐3‐hexenol informs intraspecies interactions in plants: A case study in Camellia sinensis
Authors: Jing Tingting , Zhang Na , Gao Ting , Zhao Mingyue , Jin Jieyang , Chen Yongxian , Xu Miaojing , Wan Xiaochun , Schwab Wilfried , Song Chuankui
Published: November 2018

Plants emit a variety of volatiles in response to herbivore attack, and (Z)‐3‐hexenol and its glycosides have been shown to function as defence compounds. Although the ability to incorporate and convert (Z)‐3‐hexenol to glycosides is widely conserved in plants, the enzymes responsible for the glycosylation of (Z)‐3‐hexenol remained unknown until today. In this study, uridine‐diphosphate‐dependent glycosyltransferase (UGT) candidate genes were selected by correlation analysis and their response to airborne (Z)‐3‐hexenol, which has been shown to be taken up by the tea plant. The allelic proteins UGT85A53‐1 and UGT85A53‐2 showed the highest activity towards (Z)‐3‐hexenol and are distinct from UGT85A53‐3, which displayed a similar catalytic efficiency for (Z)‐3‐hexenol and nerol. A single amino acid exchange E59D enhanced the activity towards (Z)‐3‐hexenol, whereas a L445M mutation reduced the catalytic activity towards all substrates tested. Transient overexpression of CsUGT85A53‐1 in tobacco significantly increased the level of (Z)‐3‐hexenyl glucoside. The functional characterization of CsUGT85A53 as a (Z)‐3‐hexenol UGT not only provides the foundation for the biotechnological production of (Z)‐3‐hexenyl glucoside but also delivers insights for the development of novel insect pest control strategies in tea plant and might be generally applicable to other plants.
Haplotypic differentiation between seasonal populations of Sargassum horneri (Fucales, Phaeophyceae) in Japan
Authors: Watanabe Kohei , Homma Yuri , Karakisawa Hideyuki , Ishikawa Ryoko , Uwai Shinya
Published: November 2018

Conspecific populations with different life‐cycle seasonality, particularly of their reproductive season, have been reported for many seaweed species. However, the number of genetic analyses of such seasonal populations is limited. Herein, based on the mitochondrial cytochrome oxidase subunit 3 gene (cox3) haplotype, we evaluated the genetic diversity of winter (January–March) and spring (April–June) fertile populations of the brown alga Sargassum horneri in Sado Island, Japan. Obviously, dominant cox3 haplotypes were different between seasons (even at a single site), and the N
ST values indicated the presence of a strong genetic differentiation between the two seasonal populations. AMOVA analyses confirmed that most of the genetic diversity was between seasons rather than between regions. Herein, the possibility of allochronic isolation is discussed. Considering the phylogeny of the mitochondrial cox3 DNA sequence, autumn or winter seasonal populations such as those in this investigation have evolved independently at least twice in the species. The present study shows that a shift in breeding season could be expected to conserve the genetic diversity of S. horneri in a certain region.
Why Do Bureaucrats Make Campaign Contributions to Presidential Candidates?: Evidence from 2004 to 2012
Authors: Limbocker Scott
Published: November 2018

Like other citizens, federal employees commit time and money to presidential candidates seeking federal office. However, unlike other citizens, federal employees work in an executive establishment governed by a person to whom they may donate. Are the contributions the collective will of the agency or an incorrect aggregation of individual action? By merging two original surveys of federal employees with all Federal Election Commission records of individual donations, this study examines the contribution behavior of federal employees to presidential candidates in 2004, 2008, and 2012. I find that the rate at which federal employees contribute to presidential candidates varies depending on the bureaucrat’s political beliefs, characteristics about the job the individual performs, and career values of the individual federal employee. I find little evidence that contributions vary systematically from agency‐wide characteristics.
Blood pressure target for the dialysis patient
Authors: McCallum Wendy , Sarnak Mark J.
Published: November 2018

The appropriate blood pressure (BP) target for dialysis patients remains controversial. Although there have been remarkable advances in this area in the general population, extrapolation of these data to dialysis patients is not possible. Observational studies in dialysis patients suggest that low BP is associated with worse outcomes. However, this is likely a result of confounding, considering that among dialysis patients with fewer cardiovascular comorbidities and longer survival, a more linear relationship exists between BP and mortality. Use of home BP measurements and ambulatory blood pressure monitoring (ABPM) measurements are more useful from a prognostic standpoint than in‐center predialysis BP measurements. Large clinical trial data are, however, lacking and firm recommendations on BP targets for dialysis patients are not possible.
Present and future temporal profiles and their relationship to health intentions and behaviors: A test on a Norwegian general population sample
Authors: Pozolotina Tatiana , Olsen Svein Ottar
Published: November 2018

We investigated the temporal profiles of a Norwegian general population sample and their relation to health behaviors and intentions. The profiles were based on variables from the present and future dimensions of the Zimbardo Time Perspective Inventory (ZTPI), the Consideration of Future Consequences Scale (CFCS), and the combination of both scales. The analysis revealed that there were only two stable clusters that corresponded to the present and the future profiles. Generally, CFCS‐based present and future profiles were more effective at predicting health behaviors and intentions than ZTPI‐based profiles. Profiles based on the CFCS variables were more predictive of eating behaviors. However, the profiles based on the combination of both CFCS and ZTPI were more predictive of smoking, exercising, and health intentions than the profiles based solely on the CFCS. The variation in walking was explained only by the profiles based on a combination of CFCS and ZTPI.
The pH buffering capacity of Acrisols under cassava production in Southeastern Vietnam, Chau Thanh district
Authors: Nguyen T.
Published: November 2018

This study examined the pH buffering capacity (pHBC) of haplic Acrisols under intensive cassava production in an upland area of Southeastern Vietnam where accelerated soil acidification has occurred. Soil samples (0–20, 20–40 and 40–60 cm) were taken at 12 sites under cassava and three sites under secondary dipterocarp forest as reference. The pH buffer curves were linear in the pHH2O range from 3.97 to 5.24, corresponding to a pHCaCl2 range from 3.74 to 5.20. Soil pHBC were low (1.16 ± 0.13 cmol/kg/pH) and correlated significantly with pH, Aluminium (Al) and Al‐related components. The results suggested that exchange acidity contributes significantly to soil's buffering capacity in acidic soils with low organic carbon. It also pointed to the possibility of using indicators of acidity to estimate soil pHBC. The low pHBC indicated a high risk for further acidification and also pointed to the possibility of using lime to remediate soils. Either acid buffering capacity or lime buffering capacity not pHBC in general should be considered, respectively, in acidification and liming studies. Factors and processes involved in soil acidification and liming need to be addressed as a background for soil remediation in the study area.
A preliminary soil security assessment of agricultural land in middle‐eastern China
Authors: Yang R.‐M. , Minasny B. , Ma Y.‐X. , Field D. , McBratney A. , Wu C.‐F.
Published: November 2018

Sustainable management of agricultural land requires not only an accurate assessment of the biophysical status of the soil but also estimates of the social and economic aspects of the soil. This paper focuses on soil security mapping of an approximately 80 000 km2 agricultural area in middle‐eastern China. We examined a digital soil assessment framework in mapping soil security and its five dimensions (capability, condition, capital, connectivity and codification) using digital soil maps and environmental variables. The main objective is to improve the understanding of soil protection in agricultural practices. Soil and environmental variables were coded as indicator values based on their functions, and three averaging models were used to integrate the indicators for soil security mapping. Results show that agricultural land in the study area currently has a high potential to achieve the crop production function, while there is still lack of sufficient social connectivity. Most of agricultural land has been properly protected by the public policy. More than half of the agricultural land has high security for cropping, while there is no unsecured soil. In general, most of the agricultural lands have already been well developed for cropping. The low soil security mainly contributes to the lack of proper connection to the soil. The findings suggest that digital soil security assessment is highly recommended for guiding sustainable development of agricultural land, because it could provide the knowledge of factors affecting soil security from complex multifaceted dimensions, and potential solutions to make agriculture soil more secure.
Following instructions and attempting to persuade: Performing an oral assignment in a seminar in Matvung
Authors: Fast Lesley
Published: November 2018

This article is about instructing and persuading talk in social interaction. Two interactions are examined which revolved around an oral assignment delivered in a seminar session in Matvung, Papua New Guinea. I show how the interaction is achieved collaboratively by the seminar cohort, and how the cohort members assume event‐specific roles in doing so. At the same time they are drawing upon knowledge and practice already learned in the socio‐cultural setting of Matvung day‐to‐day life, resulting in an interplay between longer‐term roles on the one hand and the roles specific to the seminar session on the other.
Characterization of the novel HLA‐A*03:315 allele by sequencing‐based typing
Authors: Cargou Marine , Elsermans Vincent , Top Isabelle , Guidicelli Gwendaline , Visentin Jonathan
Published: November 2018

HLA‐A*03:315 differs from HLA‐A*03:01:01:01 by one nucleotide substitution at codon 285 in exon 5.
Genomic dissection of pod shattering in common bean: mutations at non‐orthologous loci at the basis of convergent phenotypic evolution under domestication of leguminous species
Authors: Rau Domenico , Murgia Maria L. , Rodriguez Monica , Bitocchi Elena , Bellucci Elisa , Fois Davide , Albani Diego , Nanni Laura , Gioia Tania , Santo Debora , Marcolungo Luca , Delledonne Massimo , Attene Giovanna , Papa Roberto
Published: November 2018

The complete or partial loss of shattering ability occurred independently during the domestication of several crops. Therefore, the study of this trait can provide an understanding of the link between phenotypic and molecular convergent evolution. The genetic dissection of ‘pod shattering’ in Phaseolus vulgaris is achieved here using a population of introgression lines and next‐generation sequencing techniques. The ‘occurrence’ of the indehiscent phenotype (indehiscent versus dehiscent) depends on a major locus on chromosome 5. Furthermore, at least two additional genes are associated with the ‘level’ of shattering (number of shattering pods per plant: low versus high) and the ‘mode’ of shattering (non‐twisting versus twisting pods), with all of these loci contributing to the phenotype by epistatic interactions. Comparative mapping indicates that the major gene identified on common bean chromosome 5 corresponds to one of the four quantitative trait loci for pod shattering in Vigna unguiculata. None of the loci identified comprised genes that are homologs of the known shattering genes in Glycine max. Therefore, although convergent domestication can be determined by mutations at orthologous loci, this was only partially true for P. vulgaris and V. unguiculata, which are two phylogenetically closely related crop species, and this was not the case for the more distant P. vulgaris and G. max. Conversely, comparative mapping suggests that the convergent evolution of the indehiscent phenotype arose through mutations in different genes from the same underlying gene networks that are involved in secondary cell‐wall biosynthesis and lignin deposition patterning at the pod level.
Sunflower resistance to multiple downy mildew pathotypes revealed by recognition of conserved effectors of the oomycete Plasmopara halstedii
Authors: Pecrix Yann , Buendia Luis , Penouilh‐Suzette Charlotte , Maréchaux Maude , Legrand Ludovic , Bouchez Olivier , Rengel David , Gouzy Jérôme , Cottret Ludovic , Vear Felicity , Godiard Laurence
Published: November 2018

Over the last 40 years, new sunflower downy mildew isolates (Plasmopara halstedii) have overcome major gene resistances in sunflower, requiring the identification of additional and possibly more durable broad‐spectrum resistances. Here, 354 RXLR effectors defined in silico from our new genomic data were classified in a network of 40 connected components sharing conserved protein domains. Among 205 RXLR effector genes encoding conserved proteins in 17 P. halstedii pathotypes of varying virulence, we selected 30 effectors that were expressed during plant infection as potentially essential genes to target broad‐spectrum resistance in sunflower. The transient expression of the 30 core effectors in sunflower and in Nicotiana benthamiana leaves revealed a wide diversity of targeted subcellular compartments, including organelles not so far shown to be targeted by oomycete effectors such as chloroplasts and processing bodies. More than half of the 30 core effectors were able to suppress pattern‐triggered immunity in N. benthamiana, and five of these induced hypersensitive responses (HR) in sunflower broad‐spectrum resistant lines. HR triggered by PhRXLRC01 co‐segregated with Pl22 resistance in F3 populations and both traits localized in 1.7 Mb on chromosome 13 of the sunflower genome. Pl22 resistance was physically mapped on the sunflower genome recently sequenced, unlike all the other downy mildew resistances published so far. PhRXLRC01 and Pl22 are proposed as an avirulence/resistance gene couple not previously described in sunflower. Core effector recognition is a successful strategy to accelerate broad‐spectrum resistance gene identification in complex crop genomes such as sunflower.
Effect of osteoarthritis on the repeatability of patella tendon angle measurement in dogs
Authors: Homer Laura M. , Gomes Bárbara A. J. , Murphy Megan C. , Hammond Gawain J. C. , Parkin Tim D. H. , Broome Cameron J. A.
Published: November 2018

Objective

To evaluate the influence of osteoarthritis on the measurement of patella tendon angle (PTA) and determine intraobserver and interobserver variability.

Study design

Retrospective clinical study.

Sample population

Eighty‐seven mediolateral radiographs that were obtained prior to tibial tuberosity advancement.

Methods

Radiographic osteoarthritis was scored by 2 observers using guidelines derived from the International Elbow Working Group Protocol. Patella tendon angle was measured by 3 observers on 3 occasions, with at least 7 days between measurements. The data were statistically analyzed via weighted κ and Kruskal‐Wallis testing.

Results

A fair strength of agreement was found among observers scoring osteoarthritis, with the same grades in 48% of radiographs. The intraobserver average bias between PTA measurements 1 and 3 ranged from −0.38° to −0.94°. Interobserver bias in angle measurement ranged from −0.92° to −2.00°. Observer 1 had the narrowest range of PTA differences (12.1°), and observer 3 had the highest range of PTA differences (23.5°). Observer 2 had the lowest mean bias (−0.38°). The mean bias was lowest between observers 1 and 2 (−0.92°) and highest between observers 1 and 3 (−2.0°). The mean intraobserver standard deviation of the PTA measurement differences was 2.90°, and interobserver standard deviation of the PTA measurement differences was 2.26°. The degree of osteoarthritis did not influence PTA measurements or their variability.

Conclusion

The current study did not find evidence of an influence of osteoarthritis on PTA or on the repeatability of measurements.

Clinical significance

Our findings suggest that osteoarthritis should not affect the radiographic planning for tibial tuberosity advancement surgery. The high variances in PTA measurement in less experienced observers may influence the clinical outcome of surgery.
Trends in the use of large wood in UK river restoration projects: insights from the National River Restoration Inventory
Authors: Cashman Matthew Joseph , Wharton Geraldene , Harvey Gemma L. , Naura Marc , Bryden Alexandra
Published: November 2018

Large Wood (LW) is increasingly employed in river restoration to promote physical habitat heterogeneity and ecological diversity. To explore how LW has been used in restoration schemes across the United Kingdom in recent decades, we analysed data on 912 LW projects archived in the UK’s National River Restoration Inventory (NRRI). The number of LW schemes has continued to increase following the earliest records in the 1990s, largely tracking overall trends in river restorations. LW projects have been predominantly located in lowland, rural streams, although there has been a notable cluster in and around London. LW projects have mainly revolved around the desire to deliver hydromorphological improvements and specifically the creation of fish habitat. Most schemes used LW in simple deflector forms despite the growing scientific evidence of the benefits of using structurally complex LW. Post project monitoring has been limited and mostly restricted to photographic records. This type of database analysis can provide important insights and help guide future restoration practice.
Cultural conceptualizations of business negotiations in the Expanding Circle
Authors: Mendes de Oliveira Milene
Published: November 2018

Following recents calls for the inclusion of conceptual aspects into world Englishes research, I report in this article on conceptualizations of business negotiations by Brazilian and German business people. I conducted semi‐structured interviews in English with nine participants from each country. Subsequently, I analyzed conceptualizations of respect, success, and conflict in business negotiations by looking at ‘conceptual scripts’ underlying interviewees’ answers. Results point to differences in how the Brazilian and the German interviewees conceptualize business negotiations.
Effect of various amount of ammonium hydroxide on morphology of silica nanoparticles grown by sol-gel
Authors: Norazmi Farah Shahirah , Chaudhary Kashif Tufail , Mazalan Elham , Hader Zuhaib , Ali Jalil
Published: November 2018

Silica nanoparticles have drawn significant intentions for their potential in solar cell coating applications. These products occupy a noticeable position in a scientific research because of their easy preparation and wide uses for different technological applications. The quality of silica nanoparticles are highly dependent on the size. This study reports the synthesis of monodisperse silica nanoparticles by hydrolysis of tetraethyl orthosilicate (TEOS) in a mixture of ethanol and DI water as a solvent and ammonium hydroxide solution (NH4OH) as a catalyst. The solutions are stirred overnight and dried in a low-pressure furnace under 100 mbar for 3 hours at 60°C. Various-sized silica nanoparticles in the range 80 nm – 250 nm were examined under field emission scanning electron microscopy (FESEM). With the increasing volume of ammonia solution, an increase in the size of silica nanoparticles were observed.
Kinematic analysis on reaching activity for hemiparetic stroke subjects using simplified video processing method
Authors: Zainal Abidin Shaiful Bahri , Wan Jusoh Wan Nor Izzati , Beng Gan Kok
Published: November 2018

The purpose of the conducted study is to compare and analyse the trajectory and the kinematic variables (displacement, velocity, acceleration) of reaching activity of the upper limb part for hemiparetic stroke patient for normal side and affected side using a low cost video processing method. The research is conducted in  three different categories which are recovery, half recovery and non-recovery stroke patient group.  Six subjects were divided equally in the respective categories and they performed three trials for each reaching task, the trial was conducted by a qualified physiotherapist while the subjects were sitting on a straight-back chair or on their wheel chair. A GoPro video cameras were used to record the reaching movement in two dimensional perspective and from the recorded video, the comparison analysis was done and evaluated based on the maximum, mean and the standard deviation, kinematics performance and reaching trajectory. With this technique, was achieved implement a system that allows viewing kinematic variables as which detected in the cycle of reaching gait. The results showed a significant different between  these three group and were consistence with those reported in the previous literature
Evaluation of environmental natural radioactivity levels in soil and ground water of Barkin Ladi, Plateau state, Nigeria
Authors: Abba Habu Tela , Wan Hassan Wan Muhammad Saridan , Aziz saleh Muneer
Published: November 2018

Gamma spectrometry was used to measure gamma dose rate in air and to determine the activity concentration of naturally occurring radionuclides viz. 226Ra 232Th and 40K in soil samples collected across the geological formations of Barkin Ladi. Dose rates measured in-situ ranged from 5 nGy h−1 to 1265 nGy h−1 with a mean value of 325 nGy h−1. The activity concentrations of 226Ra ranged from 27 to 327 Bq kg−1, 34 to 457 Bq kg−1 for 232Th and 43 to 1055 Bq kg−1 for 40K. Their mean values are significantly higher than their corresponding global average values. Annual effective dose due to exposure to gamma dose is calculated at 0.34 mSv y−1. Mass concentrations of uranium (238U) and thorium (232Th) determined in groundwater samples using Inductive Coupled Plasma Mass Spectrometry (ICP-MS) ranged from 2.5 to 35 µg l−1 for 238U and 0.5 to 15 µg l−1 for 232Th. Ingestion effective dose varies between 10.5 and 142 mSv y−1 for 238U and between 0.34 and 10.2 mSv y−1 for 232Th. Mass concentration of three water samples exceed the toxicity limit of U in groundwater provided by WHO. The result revealed that human risk due to ingestion of groundwater is from chemical toxicity rather than radiological effects.  The results of this work will be useful for radio-geochemical investigation and groundwater resources management.
Vibration-Based Structural Damage Identification and Evaluation for Cylindrical Shells Using Modified Transfer Entropy Theory
Authors: Liu Guohua , Yu Ziyuan , Liang Xu , Ye Changpeng
Published: November 2018

In this paper, modified transfer entropy theory is combined with a surrogate data algorithm to produce a new method in order to identify nonlinearity in the vibration data of a damaged cylindrical shell. The proposed identification method can eliminate the necessity of acquiring baseline statistics by comparing the transfer entropy of original vibration data and that of surrogate data. Moreover, a new index ξ is established to reflect the degree of nonlinearity by quantifying the discreteness of the entropy of each group of surrogate data. Vibration tests are conducted and experimental data are analyzed to confirm the effectiveness of this method. Then, a semi-analytical method based on a Galerkin method and the classic shell theory is used to precisely predict the linear and nonlinear vibration response of a cylindrical shell under different damage circumstances. The corresponding results show that the proposed method can not only identify the structural damage but also be further applied to the evaluation of such damage for cylindrical shells. In addition, the influence of different load pressures and degrees of damage on the effectiveness of the identification method is analyzed and discussed. As verified, the proposed methodology can be potentially used for structural damage identification and evaluation in areas such as civil engineering, mechanical engineering, and ocean engineering.
Development of a New Contact Angle Control Algorithm for Level-Set Method
Authors: Li Mengnan , Zeng Kaiyue , Wonnell Louis , Bolotnov Igor A.
Published: November 2018

A contact angle control algorithm is developed and implemented in the multiphase interface tracking flow solver—phasta. The subgrid force model is introduced to control the evolving contact angle. The contact angle force is applied when the current contact angle deviates from the desired value (or range of values) and decreases to zero when it reaches the desired value. The single bubble departure simulation and the capillary flat plates simulation are performed for verification purpose. The numerical results are compared with the analytical solution with good agreement. The mesh resolution sensitivity analysis and parametric study are conducted for both simulations. Coupled with the other existing capabilities in phasta like evaporation and condensation algorithm, the contact angle control algorithm will allow us to investigate the boiling phenomenon in various conditions with lower cost (by utilizing localized mesh refinement for bubble growth region) compared to uniformly refined structured meshes and in engineering geometries.
Experimental Analysis on the Velocity of Oil Drops in Oil–Water Two-Phase Flows in Electrical Submersible Pump Impellers
Authors: Perissinotto Rodolfo Marcilli , Monte Verde William , Biazussi Jorge Luiz , de Castro Marcelo Souza , Carlos Bannwart Antonio
Published: November 2018

The objective of this research is to investigate the velocity of oil drops within the impeller of an electrical submersible pump (ESP) working with oil-in-water dispersion flows at different operational conditions. An experimental study was conducted using an ESP prototype with a transparent shell designed to enable flow visualization within the impeller channels. The tests were performed at three rotational speeds, 600, 900, and 1200 rpm, for three water flow rates, 80%, 100%, and 120% of the best efficiency point (BEP). A high-speed camera (HSC) with a lighting set captured images of the oil-in-water dispersion at 1000 frames per second. The images observation suggests the presence of a turbulent flow in the impeller. The turbulence, associated with high rotation Reynolds numbers, causes the oil drops to become smaller as the impeller rotational speed and the water flow rate increase. Despite this rotating environment, the oil drops generally have a spherical shape. Regarding the kinematics, the images processing reveals that the velocity of oil drops has a magnitude around a unit of m/s. The velocity depends on the oil drop position in the channel: oil drops that stay close to a suction blade (SB) have significantly higher velocities than oil drops that stay close to a pressure blade (PB). Considering a complex flow with water velocity profiles and pressure gradients, the analysis of oil velocity curves indicates the occurrence of accelerations that may be caused by drag and pressure forces acting on the oil drops.
Advanced Exergy Analysis of a Compression–Absorption Cascade Refrigeration System
Authors: Colorado-Garrido Dario
Published: November 2018

This work presents a theoretical thermodynamic study of a compression–absorption cascade refrigeration system using R134a and a lithium bromide–water solution as working fluids. First and second law of thermodynamics analyses were carried out in order to develop an advanced exergetic analysis, by splitting the total irreversibility and that of every component. The potential for improvement of the system is quantified, in the illustrated base-case 55.4% of the irreversibility is of avoidable nature and it could be reduced. The evaporator is the component that shows a significant potential for improvement, followed by the cascade heat exchanger, the compressor, and finally, the generator. The results of the advanced exergetic analysis can be very useful for future design and experimentation of these kinds of systems.
Cylindrical Tuber Encapsulant Layer Realization by Patterned Surface for COB-LEDs Packaging
Authors: Yu Xingjian , Hu Run , Wu Ruikang , Xie Bin , Zhang Xiaoyu , Luo Xiaobing
Published: November 2018

In this study, we proposed a flexible method to realize a cylindrical tuber encapsulant layer. Firstly, patterned LED substrate with silicone-wetting and silicone-repellency surfaces was prepared by depositing low surface energy modified nanosilica particles. Secondly, coating phosphor gel onto the LED chip. Thirdly, coating the encapsulant (silicone OE6550A/B) onto the phosphor gel layer. The silicone stops spreading at the border of silicone-wetting and silicone-repellency surfaces and its final contact angle can be adjusted to any value between the contact angle of silicone-wetting and silicone-repellency surface, so it is very easy to realize dome-shape silicone layer with contact angle of ∼90°. For COB-LEDs with LED array in series, the final silicone layer geometry is similar to the cylindrical tuber. The results show that compared to the conventional flat encapsulant layer, the proposed encapsulant layer can improve the light efficiency by > 60% for pure blue light and 13.6% for white light at correlated color temperature (CCT) of ∼5500K.
Effect of Interfacial Thermal Conductance Between the Nanoparticles
Authors: Yuksel Anil , Yu Edward T. , Cullinan Michael , Murthy Jayathi
Published: November 2018

Heat transport across nanostructured interfaces, such as between nanoparticles, has been of great interest for advanced thermal management. Interfacial thermal conductance, G, is central to understanding thermal heat transport between nanoparticles that have a contact point between each other as well as the surrounded medium. In this study, we show that G dominates the heat transport compared to the conduction and radiation heat transfer modes between the nanoparticles for values higher than ∼20 (MW/m2K). We also investigate the effect of radius of contact between the nanoparticles on the overall modes of heat transfer.
Weather Analysis Using Neural Networks for Modular Data Centers
Authors: Adejokun Feyisola , Siddarth Ashwin , Guhe Abhishek , Agonafer Dereje
Published: November 2018

The objective of this work is to introduce the application of an artificial neural network (ANN) to assist in the evaporative cooling in data centers. To achieve this task, we employ the neural network algorithms to predict weather conditions outside the data center for direct evaporative cooling (DEC) operations. The predictive analysis helps optimize the cooling control strategy for maximizing the usage of evaporative cooling thereby improving the efficiency of the overall data center cooling system. A typical artificial neural network architecture is dynamic in nature and can perform adaptive learning in minimal computation time. A neural network model of a data center was created using operational historical data collected from a data center cooling control system. The neural network model allows the control of the modular data center (MDC) cooling at optimum configuration in two ways. First way is that the network model minimizes time delay for switching the cooling from one mode to the other. Second way, it improves the reaction behavior of the cooling equipment if an unexpected ambient condition change should come. The data center in consideration is a test bed modular data center that comprises of information Technology (IT) racks, Direct Evaporative cooling (DEC) and Indirect Evaporative Cooling (IEC) modules; the DEC/IEC are used together or in alternative mode to cool the data center room. The facility essentially utilizes outside ambient temperature and humidity conditions that are further conditioned by the DEC and IEC to cool the electronics, a concept know as air-side economization.

Various parameters are related to the cooling system operation such as outside air temperature, IT heat load, cold aisle temperature, cold aisle humidity etc. are considered. Some of these parameters are fed into the artificial neural network as inputs and some are set as targets to train the neural network system. After the training the process is completed, certain bucket of data is tested and further used to validate the outputs for various other weather conditions. To make sure the analysis represents real world scenario, the operational data used are from real time data logged on the MDC cooling control unit. Overall, the neural network model is trained and is used to successfully predict the weather conditions and cooling control parameters. The prediction models have been demonstrated for the outputs that are static in nature (Levenberg Marquardt method) as well as the outputs that are dynamic in nature i.e., step-ahead & multistep ahead techniques.
Fundamental Study of Polymer to Metal Bonding in Integrated Circuit Packaging
Authors: Thanu Dinesh P. R. , Danaei Roozbeh , Bermudez Alexander , Chan Sergio A. , Prstic Suzana
Published: November 2018

Nowadays microelectronic packaging has become a billion dollar business. Due to the increased material and production costs per package, manufacturing yield loss in this state-of-art business is expected to be at a bare minimum which is tough to persevere in a high volume manufacturing environment. Additionally, high performance and varied power computing needs in the electronic business demands microprocessors with different form factors and complex package designs. One of the most common joint which is extensively used in such a complicated package is the polymer to metal bonding. In the latest technology products involving high package warpage, interfacial bonding has to be strong enough to withstand the dynamic warpage and high mechanical stresses associated with it and hence the reliability of polymer to metal adhesion is critical. In this paper, fundamental mechanisms related to adhesion phenomena of polymer-metal interface are proposed. Adhesive failure modes related to polymer-metal bonding and key variables influencing the bonding of silicone based polymer material to nickel electroplated on copper in an integrated circuit heat spreader assembly are experimentally studied. Factors modulating polymer to metal bonding including interfacial chemistry, surface contamination and material roughness are evaluated.
Numerical Approach to Cold Gas Spray on Ceramic Substrates for Power Electronics Packaging
Authors: Echeverría Marco J. , Quintero Pedro O. , Ibitayo Dimeji , Boteler Lauren
Published: November 2018

In power electronic, ceramic substrates are used owing to their high thermal conductivity and dielectric strength. These substrates cannot withstand high voltages in the range of 20kV because thickness limitations inherit from the direct bond copper manufacturing method. This manufacturing process uses high temperature in order to bond the material layers. This negatively affects the material’s reliability due to the differing materials thermal expansion coefficients and the resulting residual stress. All this results in hindering the ceramic substrate in obtaining a higher dielectric strength. In contrast, cold gas spray has the potential to provide higher reliability due to its bonding mechanism, which relies on plastic deformation of solid particles at very high strain rates during impact to create a mechanical bond, forming a thick deposit. However, cold gas spray on ceramics has not been widely studied due to their brittleness and their inability to form a metallic bond. This work is aimed at providing an effective processing parameter map of the cold gas spray process to achieve a thick copper deposit on aluminum nitride on the basis of the comparison of experimental results with a numerical model and finite element simulation formulated in Mathematica and ABAQUS, respectively.
Long-Term Effects of Power Quality and Power Cycling on Thermoelectric Module Performance
Authors: Patel Viral K. , Wang Hsin , Gluesenkamp Kyle R. , Gehl Anthony , Ormston Geoffrey , Kirkman Emily
Published: November 2018

Thermoelectric (TE) modules used in a heat pumping mode are increasingly being used for various applications involving heating and cooling. As their use becomes more prevalent and extends to lower cost applications using inexpensive commodity power supplies, it is important to characterize the long-term effects of power cycling and power quality on their performance. Two power supplies were evaluated with different levels of periodic and random deviations (PARD) from ideal DC power. This paper presents the results of an accelerated aging experimental study on intermittent power cycling of TE modules over the span of 5 actual months with each power supply. TE performance metrics that were monitored at specific time intervals are the AC resistance and figure of merit. The applied voltage, power consumption, TE hot and cold side temperatures and air temperatures were continuously measured. The experimental results indicate that the low-quality power supply quality had only a minor influence on properties and integrity of the TE modules, and is suitable for applications requiring intermittent use without a substantial reduction in performance.
Reduced Working Temperature of Quantum Dots-Light-Emitting Diodes Optimized by QDs@Silica-on-Chip Structure
Authors: Xie Bin , Liu Haochen , Sun Xiao Wei , Yu Xingjian , Wang Kai , Luo Xiaobing
Published: November 2018

White light-emitting diodes (WLEDs) composed of blue LED chip, yellow phosphor, and red quantum dots (QDs) are considered as a potential alternative for next-generation artificial light source with their high luminous efficiency (LE) and color-rendering index (CRI). While, QDs’ poor temperature stability and the incompatibility of QDs/silicone severely hinder the wide utilization of QDs-WLEDs. To relieve this, here we proposed a separated QSNs/phosphor structure, which composed of a QSNs-on-chip layer with a yellow phosphor layer above. A silica shell was coated onto the QDs surface to solve the compatibility problem between QDs and silicone. With CRI > 92 and R9 > 90, the newly proposed QDs@silica nanoparticles (QSNs) based WLEDs present 16.7 % higher LE and lower QDs working temperature over conventional mixed type WLEDs. The reduction of QDs’ temperature can reach 11.5 °C, 21.3 °C and 30.3 °C at driving current of 80 mA, 200 mA and 300 mA, respectively.
Numerical Investigation of Shape Effect on Microdroplet Evaporation
Authors: Shuai Shuai , Du Zichen , Ma Binjian , Shan Li , Dogruoz Baris , Agonafer Damena
Published: November 2018

As electronic devices continue to shrink in size and increase in functionality, effective thermal management has become a critical bottleneck that hinders continued advancement. Two-phase cooling technologies are of growing interest for electronics cooling due to their high heat removal capacity and small thermal resistance (< 0.3 K-cm2/W) [1]. One typical example of a two-phase cooling method is droplet evaporation, which can provide a high heat transfer coefficient with low superheat. While droplet evaporation has been studied extensively and used in many practical cooling applications (e.g., spray cooling), the relevant work has been confined to spherical droplets with axisymmetric geometries. A rationally designed evaporation platform that yields asymmetric meniscus droplets can potentially achieve larger meniscus curvatures, which give rise to higher vapor concentration gradients along the contact line region and therefore yield higher evaporation rates. In this study, we develop a numerical model to investigate the evaporation behavior of asymmetrical microdroplets suspended on a porous micropillar structure. The equilibrium profiles and mass transport characteristics of droplets with circular, triangular, and square contact shapes are explored using the Volume of Fluid (VOF) method. The evaporative mass transport at the liquid-vapor interface is modeled using a simplified Schrage model [2]. The results show highly non-uniform mass transport characteristics for asymmetrical microdroplets, where a higher local evaporation rate is observed near the locations where the meniscus has high curvature. This phenomenon is attributed to a higher local vapor concentration gradient that drives faster vapor diffusion at more curved regions, similar to a lightning rod exhibiting a strong electric field along a highly curved surface. By using contact line confinement to artificially tune the droplet into a more curved geometry, we find the total evaporation rate from a triangular-based droplet is enhanced by 13% compared to a spherical droplet with the same perimeter and liquid-vapor interfacial area. Such a finding can guide the design and optimization of geometric features to improve evaporation in high performance electronics cooling systems.
Experimental Analysis of Chiller Cooling Failure in a Small Size Data Center Environment Using Wireless Instrumentation
Authors: Tradat Mohammad , Sammakia Bahgat , Alissa Husam , Nemati Kourosh
Published: November 2018

Given the vital rule of data center availability and since the inlet temperature of the IT equipment increase rapidly until reaching a certain threshold value after which IT starts throttling or shut down because of overheat during cooling system failure. Hence, it is especially important to understand failures and their effects. This study presented experimental investigation and analysis of a facility-level cooling system failure scenario in which chilled water interruption introduced to the data center. Quantitative instrumentation tools including wireless technology such as wireless temperature and pressure sensors were used to measure the discrete air inlet temperature and pressure differential though cold aisle enclosure, respectively. In addition, Intelligent Platform Management Interface (IPMI) and cooling system data during failure/recovery were reported. Furthermore, the IT equipment performance and response for opened and contained environments were simulated and compared. Finally, an experiment based analysis of the Ride Through Time (RTT) of servers during chilled water interruption of the cooling infrastructure presented as well. The results showed that for all three classes of servers tested during the cooling failure, CAC helped keep the server’s cooler for longer. The containment provided a barrier between the hot and cold air streams and caused slight negative pressure to build up, which allowed the servers to pull cold air from the underfloor plenum. In addition, the results show that the effect of CAC in containment solutions on the IT equipment performance and response could vary and depend on the server’s airflow, generation and hence types of servers deployed in cold aisle enclosure. Moreover, it was shown that when compared to the discrete sensors, the IPMI inlet temperature sensors underestimate the Ride Through Time (RTT) by 42% and 12% for the CAC and opened cases, respectively.
Creep Response of Assemblies Bonded With Pressure Sensitive Adhesive (PSA)
Authors: Huang Hao , Jiang Qian , Dasgupta Abhijit , Mirbagheri Ehsan , Darbha Krishna
Published: November 2018

Creep response of joints bonded with single-layered pressure sensitive adhesives (PSAs) was investigated in this study. PSAs are becoming more and more popular in the electronic industry as bonding media because of their ease of design, fast accurate bonding, environmentally-friendly bonding and ease of reworking. Such adhesive bonds are expected to experience complex, sustained loading conditions in service; e.g. loading due to large mass components, shock, temperature, or alignment mismatch of substrates. Stress-strain behavior of PSA bonding assembly has been extensively studied through experiments and simulations, including the effects of loading conditions (loading rate and temperature), PSA configurations (thickness of adhesive and single/double-layered PSAs), and bonding substrate surface properties (substrate material and surface roughness). However, the literature regarding the creep response of PSA-bonded assemblies is lacking and there is no literature on modeling methodologies for the creep response of such bonding systems.

Similar to the stress-strain behavior of PSA-bonded assemblies, the creep response includes transitions between multiple hardening and softening phases. Experimental results indicate that the secondary creep rate can change by up to two orders of magnitude after each transition, which is too significant to ignore when estimating the creep deformation of joints bonded with this material system. The number of transitions is related to the configuration of the PSA system, i.e. the single-layered PSA has one transition while double-layers PSAs may have multiple transitions due to the additional interface(s) introduced by the carrier layer. This unique secondary creep behavior comes from the competition between hydrostatic stress relaxation and strain hardening, caused by cavitation and fibrillation processes, respectively. The total stress applied on the joint is equal to the summation of deviatoric stress and hydrostatic stress. An advanced model based on the stress-strain ‘block’ model [5–7] is developed for evaluating the creep response. This model has the capability to control the initiation and growth of cavities in the bulk of the PSA and at the interface between PSA and substrate. This model is able to capture the nonlinear visco-plastic behavior of the PSA fibrils and estimate the effects of flexible carrier layer on the transitions in creep curves. The model prediction shows reasonable agreement with experimental results in terms of the characteristic features in creep strain histories.