bluuebunny/crossref_metadata_2025 huggingface dataset:
Sentiment Classification Using Text Embedding for Thai Teaching Evaluation
Authors: Boonchuay Kesinee
Published: January 2019

Sentiment classification gains a lot of attention nowadays. For a university, the knowledge obtained from classifying sentiments of student learning in courses is highly valuable, and can be used to help teachers improve their teaching skills. In this research, sentiment classification based on text embedding is applied to enhance the performance of sentiment classification for Thai teaching evaluation. Text embedding techniques considers both syntactic and semantic elements of sentences that can be used to improve the performance of the classification. This research uses two approaches to apply text embedding for classification. The first approach uses fastText classification. According to the results, fastText provides the best overall performance; its highest F-measure was at 0.8212. The second approach constructs text vectors for classification using traditional classifiers. This approach provides better performance over TF-IDF for k-nearest neighbors and naïve Bayes. For naïve Bayes, the second approach yields the best performance of geometric mean at 0.8961. The performance of TF-IDF is better suited to using decision tree than the second approach. The benefit of this research is that it presents the workflow of using text embedding for Thai teaching evaluation to improve the performance of sentiment classification. By using embedding techniques, similarity and analogy tasks of texts are established along with the classification.
Antioxidant Activities of Chaba Maple (Hibiscus acetosella) Flower Extract
Authors: Thungmungmee Suradwadee , Wisidsri Nakuntwalai , Khobjai Warachate
Published: January 2019

Phenolic compounds are a large group of phytochemical compounds in plants which have antioxidant activity. Hibiscus species were used in traditional medicine in North-America with biological activities. In this study, total phenolic content, total flavonoid content and antioxidant activities of Chaba maple (Hibiscus acetosella) flower extract (CFE) in Thailand were investigated. The total phenolic and flavonoid contents were determined by Folin-Ciocalteu assay and aluminum chloride colorimetric method, respectively. Antioxidant activities of CFE were examined by DPPH radical scavenging, ferric reducing antioxidant power (FRAP) and nitric oxide (NO) radical scavenging ability methods. The results showed that total phenolic content and total flavonoid content were 91.22±0.68 mg gallic acid equivalent/g fresh matter and 0.31±0.01 mg quercetin equivalent/g fresh matter, respectively. For antioxidant activities, IC50 of DPPH radical scavenging was 57.93±0.37 μg/ml, the power of ferric reducing was 1,707.18±1.99 μM and IC50 of NO radical scavenging was 229.30±0.71 μg/ml. In conclusion, CFE could be potentially used as a new natural bioactive ingredient for nutritional supplements and cosmetics application.
High Performance Liquid Chromatography Using Ultrasonic Extraction for Benzoic Acid Analysis in Curry Paste Samples
Authors: Thongsrinoon Nararat , Phiwdee Netnapha , Duangsa Yanada , Muensub Khaengkhae , Duang-Iad Vichayaporn
Published: January 2019

Benzoic acid analysis in curry paste samples were carried out by using high performance liquid chromatography using ultrasonic extraction. Methanol-0.05 M ammonium acetate buffer pH 4.40 in the ratio of 55:45 (%v/v) at a flow rate of 1.00 mL/min was used as the mobile phase and benzoic acid detection was performed at 226 nm using an UV-Visible detector. Under the optimum conditions, linearity of spiked samples ranged from 50 to 3,000 mg/kg. Matrix matched calibrations had determined that benzoic acid contents in southern sour, red, and green curry paste samples were 67.59, 78.62 and 72.33 mg/kg, respectively. Recoveries were obtained from 89.34 to 101.70%, 83.37 to 130.30% and 92.75 to 113.56% with R.S.D. ranged from 2.71 to 6.53%, 4.02 to 11.58% and 5.81 to 6.35%, for southern sour, red, and green curry paste samples, respectively.
Evaluation of Free Radical Scavenging Activity and Reducing Power of Careya arborea Roxb.
Authors: Ninlaor Wanvisa , Thongom Thaksaorn , Phoomphong Chawapon , Khobjai Warachate
Published: January 2019

Antioxidant plays an important role in inhibiting and scavenging radicals, thus providing protection for human against infection and degenerative diseases. The aim of this study was to evaluate the effect of the solvent on the extraction of the antioxidant compounds from Careya arborea (CA) Roxb. The leaves of CA were extracted by using water, ethanol, methanol, and chloroform. The total phenolic content of the extracts was determined by the Folin-Ciocalteu reagent and their antioxidant activity was measured using 2, 2-diphenyl-1 picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) methods. The antioxidant activities of the extracts for DPPH and FRAP were in the order: water > methanol > ethanol > chloroform extract. According to the results, water is the most suitable solvent for extraction of active substances with antioxidant activities.
Evaluation of Hurdle Technology on Shelf Life Extension of Thai Red Curry Paste and Sour Curry Paste
Authors: Phoem Atchara Nuphet , Sankalee Sumitra , Aryae Pirada
Published: January 2019

The effects of reduced water activity and different packaging materials were investigated regarding shelf life extension of Thai red curry paste and sour curry paste. Curry pastes supplemented with 10% sodium chloride and dried at 50°C for 120 minutes and original red and sour curry pastes were evaluated for physical, chemical and microbiological properties. Results showed that L*, a*, and b* values and total viable count in supplemented curry pastes were less than in original curry pastes. Staphylococcus aureus, Bacillus cereus, Clostridium perfringens, Salmonella spp. and Escherchia coli were not detected in both supplemented and original curry pastes. Protein, fat, fibre, carbohydrate, total phenolic content and IC50 value of supplemented curry pastes did not differ from the original curry pastes. Both supplemented and original curry pastes were vacuum packed in aluminium foil and nylon bags and stored at 25°C for 8 weeks. Results revealed that nylon bags gave higher shelf life extension for supplemented curry pastes over the storage period. Values of water activity, moisture, aflatoxin, total viable count and mould count in supplemented curry pastes packed in nylon bags were less than the Thai community product standards.
Production and Application of Biosurfactant Produced by Agrobacterium rubi L5 Isolated from Mangrove Sediments
Authors: Dikit Paweena , Maneerat Suppasil , Saimmai Atipan
Published: January 2019

An effective biosurfactant-producing bacteria, isolate L5, was isolated from mangrove sediments from both east coast and west coast of Southern of Thailand. Analysis of the 16S rRNA gene sequence confirmed that isolate L5 was Agrobacterium rubi with 100% homology. The biosurfactant production was performed using a mineral salt medium (MSM) with molasses as a carbon and commercial monosodium glutamate (MSG) as nitrogen sources. Under optimized conditions, A.rubi L5 was able to grow and produce biosurfactant with the yield of 4.62 g/l at 54 h of cultivation. It could reduce the surface tension of pure water from 72.0 to 25.5 mN/m and exhibit emulsification activity toward palm oil with 65.4%. The biosurfactant found to be stable even under extreme pH, temperature and salinity conditions. The results revealed the potential use of a biosurfactant produced by A. rubi L5 to enhance mobilization sorbed motor oil from environment in comparison with those of synthetic surfactants, i.e. a nonionic surfactant Tween 80 and anionic surfactants sodium dodecyl sulfate.
Effect of Amines Addition on Properties and Stability of PEGylated Au Nanoparticles
Authors: Reznickova Alena , Slavikova Nikola , Švorčík Václav
Published: January 2019

In this paper, we propose preparation of PEGylated AuNPs by direct sputtering of Au into pure PEG with subsequent addition of amine terminated PEG. Effect of post-deposition amine addition on properties, aging and thermal stability will be discussed. Transmission electron microscopy and dynamic light scattering measurements showed that we have prepared non-agglomerated spherical NPs with size ranging from 2.9 to 5.9 nm depending on parameters of the preparation. Aging and thermal stability results revealed significant changes in the spectra after addition of PEG–NH2. Differences in the optical absorption spectra can be assigned to change of refractive index (concentration of amine groups on NPsʼ surface) on the metal core and solvent interface with time and temperature.
Calculation and Measurement of Elastic Modulus of Nano BaTiO3 Enhanced IPMC
Authors: Wang Man
Published: January 2019

The Mechanical parameters of elastic modulus about the preparation technology of BaTiO3/IPMC (Ionic Polymer Metal Composite) were studied. In order to get the relationship between the elastic modulus and the different content of BaTiO3/IPMC the Mori-Tanaka method based on Eshelby equivalent inclusion theory was used. In order to verify the correctness of the model, Solution casting method was used to prepare different content of BaTiO3/IPMC (100:1,100:3,100:5,100:7). The elastic modulus of IPMC was texted by tensile testing and the bending test of cantilever. The result shows that: The elastic modulus of IPMC film increased by 6.3% ~ 84.7% with addition of BaTiO3. It was proved that the reinforced fillers could greatly improve the elasticity modulus of IPMC.
Natural-Fiber-Reinforced Polymer Composites for Automotive Parts Manufacturing
Authors: Oliver Bernardo , Caballero Samuel Sánchez , Fenollar Octavio , Sellés M.A.
Published: January 2019

Composite materials are widely used in the industry for their physical and mechanical properties. The objective of this work is the characterization of some composite materials with natural fibers, in order to determine the suitability in a later use in automotive components. For this purpose, we intend to obtain a model of tensile tests using finite element software, in order to be able to dimension real components.
Comparison of Semisolid Microstructure Evolution of Wrought Nickel Based Superalloy GH4037 with Different Solid Fraction
Authors: Xiao Guan Fei , Jiang Ju Fu , Wang Ying , Liu Ying Zhe
Published: January 2019

The research on semisolid metal forming of Ni-based superalloys is limited because of the difficulties in preparing semisolid billets. Traditional methods for fabricating semisolid billets are SIMA and RAP. In order to decrease the processing procedures, a new method called semi-solid isothermal treatment of wrought superalloy (SSITWS) was used to fabricate semisolid billets in this paper. In order to get the optimal parameters to fabricate Ni-based GH4037 semisolid billets, the effects of isothermal temperature and soaking time on microstructure evolution were investigated. The isothermal temperature ranges from solidus to liquidus, and the soaking time ranges from 10min to 60min. The results show that near-globular grains can be obtained only in the semi-solid state with appropriate solid fractions. When the solid fraction was high, the shape of grains was irregular and the average size of grains was large and inhomogeneous. When the isothermal temperature reached 1350°C, spherical grains appeared, and many small intragranular liquid droplets existed. During the appropriate isothermal temperature range, from 1350°C to 1380°C, the shape of solid grains was globular and the size of solid grains was homogeneous. At the same time, the size of the grains and the roundness of the grains increased with the increasing of isothermal temperature.
Effect of Nano-SiC on Microstructure and Mechanical Properties of AZ91 Magnesium Alloy Processed by Thixomolding
Authors: Rogal Łukasz , Baran Bogusław , Bobrowski Piotr , Tarasek Anna , Ozga Piotr , Litynska-Dobrzyńska Lidia
Published: January 2019

Magnesium injection molding technology was used to produce Mg based nanocomposites. AZ91 chips were mixed with 5 wt.% of β-SiC nanoparticles in solid state and fed to pre-heated cylinder of prototype injection molding machine. Using screw rotation, granules were transferred to nozzle area at simultaneous intensive shearing and mixing of slurry containing reinforcement phases. Injection process was conducted at 595 °C, which corresponded to about 90% liquid phase and cast to steel die preheated to 150 °C. Detailed characterization of microstructure was performed using SEM and TEM microscopes. Composite microstructure consisted of α(Mg) globular grains with size of about 60 μm and volume of 7-10% surrounded by mixture of proeutectic magnesium solid solution with irregular shape and average size of 12 μm as well as fine eutectic mixture (α(Mg) + β-Mg17Al12). Additionally, TEM-BF image showed β-SiC nanoparticles with size of 20-50 nm in the area of eutectic. Hardness and compression strength of AZ91 nanocomposites increased from 58 to 75 HV and from 200 to 235 MPa, respectively.
Refinement of Primary Silicon Grains in Semi-Solid Al-25%Si Hypereutectic Aluminum Alloy Slurry
Authors: Mao Wei Min , Yan Peng Yu , Zheng Z.K.
Published: January 2019

s: The semi-solid slurry of Al-25%Si hypereutectic aluminum alloy was prepared through a copper serpentine pouring channel, the effect of pouring temperature and numbers of channel bend on the slurry microstructure was investigated. The results show that the primary silicon grains in Al-25%Si hypereutectic alloy solidified at a traditional condition are very large and the average silicon grain size is about 65.3μm, however, when the liquid Al-25%Si alloy is poured through a copper serpentine pouring channel, the primary silicon grains are fined obviously. If the channel has three bends and the pouring temperature is 747°C,the average silicon grain size in the slurry is about 33.7μm. If the channel has four bends and the pouring temperature is 747°C, the average silicon grain size in the slurry is about 30.9μm. If the channel has seven bends and the pouring temperature is 747°C, the average silicon grain size in the slurry is about 28.6μm. The analysis shows that the chilling effect of the inner channel wall precipitates primary silicon nuclei, and so the primary silicon grains of Al-25%Si alloy are fined greatly. Meanwhile, the subsequent washing of the alloy melt also promotes the separation of primary silicon grains from the inner wall and the primary silicon grains are further fined. The above research work demonstrates eventually that the copper serpentine pouring channel process is a good method for fining the primary silicon grains in hypereutectic Al-25%Si alloy rather than using chemical fining agent phosphorus as in traditional process.
Characterization of Microstructure and Shrinkage Porosity of a Semi-Solid Metal Slurry in Gravity Die Casting
Authors: Thanabumrungkul S. , Jumpol W. , Canyook Rungsinee , Meemongkol N. , Wannasin Jessada
Published: January 2019

Current aluminum automotive parts such as wheels, engine and transmission components are produced by tilted gravity die casting for control gas porosity. But, there are still problems resulting in inefficient production: shrinkage porosity, microstructure size and uniformity. Shrinkage porosity is one of the major issues which affects mechanical properties such as strength and elongation in tilted pour permanent mold. Recent work using slurry casting technique has shown potential in gravity sand casting. Results show that the casting parts have complete filling at low solid fractions and the casting yield is also higher than conventional gravity sand casting. This paper extends important work for potential industrial applications in gravity die casting: microstructure size, uniformity, solid fraction control for micro shrinkage level.
Semi-Solid Casting of Aluminium from an Industrial Point of View
Authors: Winklhofer Johannes
Published: January 2019

Company SAG (Salzburger Aluminium AG) is a supplier of fuel tanks, LNG and hydraulic tanks, air reservoirs and structural applications for the commercial vehicle and automotive industry. The company’s expertise is welding but SAG also has a 25 years history in Semi-Solid casting starting in 1993 when the first Thixocasting cell was installed in Lend/Austria. Since then SAG is participating on the diverse casting market and competes with other processes looking for applications for which Semi-Solid processing has a unique selling proposition. This contribution gives examples of industrialized components and will outline their significant characteristics and advantages in comparison to conventional casting processes. Furthermore the development of Semi-Solid cast components, the production process chain as well as commercial aspects will be outlined. The bottom line is that usually it is not a single advantage of Semi-Solid casting that will make a product attractive for the customer but a combination of several of them. Moreover it is not just the casting process itself but the efficiency of the whole production process chain that will result in a commercially successful product.
Damaging of Ultrasonic Horn for Semisolid Feedstock Production
Authors: Montesano Lorenzo , Pola Annalisa , Tocci Marialaura , Gelfi Marcello , La Vecchia Giovina Marina
Published: January 2019

Ultrasound treatment is one of the known method to obtain the globular microstructure for semisolid processing of aluminum alloys. Notwithstanding the numerous advantages, the main industrial limit of this method is the low service life of the horn due to the combined hot corrosion and erosion phenomena. Various approaches are reported in literature to overcome this problem, but a real satisfactory option does not seem to be available yet. In this paper, the behavior of a H11 tool steel sonotrode coated with a thin layer of TiAlCN is investigated and compared with the performance of an uncoated steel one. The lifetime of the horn was evaluated in terms of effectiveness in semisolid feedstock material preparation. For this purpose, the microstructure of semisolid cast samples obtained after different working times was analyses by optical and scanning electron microscopy. Moreover, melt contaminations due to the probe dissolution were also evaluated. The applied coating exhibited a significant resistance to separate hot corrosion in liquid Al alloy and cavitation erosion phenomena in water. However, the combined effect of the two damaging mechanisms during ultrasound treatment of the molten alloy leaded to coating removal and to a horn consumption comparable to that of bare steel.
Analysis of the 355 Aluminium Alloy Microstructure for Application in Thixoforming
Authors: de Paula Leandro Cássio , Tokita Shun , Kadoi Kota , Inoue Hiroshige , Zoqui Eugênio José
Published: January 2019

The 355 aluminium alloy is known to have excellent thermodynamic characteristics that render it suitable as a raw material for rheocasting and thixoforming. However, besides the controllable transition from solid to liquid phase, the refined microstructure required in the semisolid range is one of the key factors with a strong influence on the rheology of the material. This paper intends to analyse the in situ behaviour of the microstructure, in terms of morphological change, using high-temperature laser scanning confocal microscopy. The 355 alloy was prepared via conventional casting, and refined with a 30-s exposition via ultrasonic melt treatment (UST - 20 Hz, 2 kW). The material was reheated up to the thixoforming target temperature of 595 °C at which it was maintained for 0, 30, 60, 90, and 120 s, after which all the samples were cooled in water. The samples subjected to UST prior to the heat treatment were more refined in terms of microstructural evolution; they exhibited reduction in grain size (~107 ± 16 μm), smallest primary phase particle size (~81 ± 7 μm), and high circularity shape factor (~0.59 ± 0.19 μm). In situ observation methods were employed to analyse evolution mechanisms such as Ostwald ripening and coalescence.
Effect of Particle Size and Weight Percent of SiC Particles on Microstructure and Hardness of A356-SiC Composites Produced by Semi-Solid Stir Casting
Authors: Saenpong Phuriphut , Talangkun Sukangkana , Sanyajivin Satawat , Kapranos Plato
Published: January 2019

This research investigates the effects of particle size and weight percent on the hardness of A356 matrix composite reinforced with SiC particulates produced by semi-solid stir casting. The particle sizes of the reinforcing phase were in the form of 37 and 100 μm SiC powders with loading content of 5, 10, 15 and 20 percent by weight. A356 alloy was melted and SiC powder was then gradually added into the continuously stirred slurry to promote uniform distribution of the particulates. It has been found that in the as cast condition, the average hardness values of A356 reinforced with different amounts of 37μm SiC, increase as expected with increasing amounts of particulates. A356 reinforced with 100 μm 10 wt% SiC, followed by T6 treatment, exhibited the highest percentage of hardness increment.
A Study on Bar Drawing Process of A356 Alloy in Semisolid State
Authors: Simlandi Sudip , Barman Nilkanta , Chattopadhyay Himadri
Published: January 2019

A bar drawing process of an aluminium alloy in semisolid state is presented in the work. The drawing process depends on various parameters such as temperature, die-angle, shear rate etc., accordingly a study is considered. The work involves development of a model to investigate the drawing process of A356 alloy in semisolid range. The rheology of the alloy in semisolid state shows a distinct behaviour and reduces energy requirement during the drawing process. In the context, a model suitably represents the rheology of the alloy is considered to perform a study of the process in details. An analytical and a numerical solutions are combined together to solve the governing equations. Finally, in the work, the distribution of velocity, viscosity variation and drawing power of the semisolid alloy under shear are predicted in the domain. It is found that the energy requirement is reasonably less in case of semisolid bar drawing process compare to a conventional bar drawing process. Finally, the drawing power required to deform a conventional solid A356 alloy is compared with that of the semisolid A356 alloy.
Semi-Solid Processing of Nano-SiCP/ Al-Si Composites and Mechanical Properties with Rheo-Casting
Authors: Wu Shu Sen , Yuan Du , Chen Qiang , Lü Shu Lin , Huang Zhi Wei
Published: January 2019

Generally nano-SiC particles are difficult to be added into molten aluminum metals because of poor wettability. Nano-SiC particles reinforced A356 aluminum alloy composites were prepared by a new process, i.e., a molten-metal process combined with mechanical stirring at semi-solid state and ultrasonic vibration method. The nano particles were β-SiCp with an average diameter of 40 nm, and pre-oxidized at about 850°C to form an oxide layer with thickness of approximately 3.6 nm. The SEM analysis results show that nano-SiC particles are dispersed well in the matrix and no serious agglomeration is observed. The tensile strength and elongation of the 2wt.% nano-SiCp/A356 composite in as-cast state are 259 MPa and 5.3%, and they are improved by 20% and 15% respectively compared with those of the A356 alloy.
Effect of Primary α-Al Morphology in Slurry on Segregation during 357 Semi-Solid Die Casting
Authors: Zhang Hong , Li Da Quan , Qu Wen Ying , Zhang Fan , Luo Min , Midson Stephen P. , Zhu Qiang
Published: January 2019

Controlling the morphology of the microstructure of the slurry is important during semi-solid die casting. For this project, semi-solid slugs were produced using the SEED (Swirled Enthalpy Equilibrium Device) process, where a fully liquid metal is poured into a steel crucible and cooled into the semi-solid temperature range, and the crucible and slurry are then swirled and cooled to the appropriate temperature (and solid fraction) for semi-solid casting. The pouring temperature of the melt into the crucible during SEED processing has been shown to influence the morphology and size of the aluminum solid particles within the slurry, which can influence the distribution and segregation of the solid particles during die casting. In this study, a specially-designed die with a serpentine-shaped flow channel has been used to study the distribution of the solid particles during semi-solid die casting. The experimental results show that a dendritic structure is formed when the liquid is poured from a high temperature, while a globular semi-solid morphology is more easily formed when poured from a low superheat. The current results also show that a dendritic structure leads to severe segregation during die casting.
Fabrication of Thin Heat Sinks by the Die Casting of Semisolid Al-25%Si
Authors: Haga Toshio , Fuse Hiroshi , Terao Masru
Published: January 2019

The viability of casting heat sinks with thin fins using Al-25%Si was investigated, based on assessing cooling curves as well as fluidity tests and emissivity analyses of the resulting heat sinks. The fluidity, castability and emissivity of the semisolid die-cast Al-25%Si were excellent and superior to the results obtained using liquid die-cast A383, an aluminum alloy typically employed for casting. The cooling curves indicate that the significant latent heat of the Si in the alloy improves the fluidity and castability of the material. The addition of P did not greatly affect the refinement of primary Si in the alloy. These findings show that Al-25%Si is suitable for the die-casting of heat sinks with thin fins.
Industrialized Application of Rheo-HPDC Process for the Production of Large Thin-Walled Aluminum Alloy Parts
Authors: Qi Ming Fan , Kang Yong Lin , Qiu Quan Quan
Published: January 2019

A simplified and efficient process, namely air-cooled stirring rod (ACSR), was proposed to prepare semisolid slurry of aluminum alloys. An advanced integrated rheological high pressure die-casting (Rheo-HPDC) technology was established by combining the ACSR equipment with HPDC machines to produce high quality aluminum alloy products. Microstructures, surface qualities, mechanical properties, corrosion resistances and thermal conductivities of the Al-8Si alloy parts prepared by Rheo-HPDC were investigated and compared to those prepared by traditional HPDC. The results indicated that the Rheo-HPDC process can prepare aluminum alloy parts in which the primary particles are fine and spherical, and there is few shrinkage porosity. Multifarious high quality large thin-walled aluminum alloy parts, such as filter shells, cooling shells, antenna crates and mounting brackets for communication, were produced by the process. Rheo-HPDC alloys showed improved surface quality to those formed by traditional HPDC, and the surface roughness is small and avoid employing CNC to surface finish. Also, compared with HPDC alloys, the alloys prepared by Rheo-HPDC have an increased mechanical properties and thermal conductivity due to high density and refined microstructure. Furthermore, Rheo-HPDC aluminum alloys indicated a remarkable improvement in corrosion resistance as shown by the results of electrochemical and weight loss experiments.
Semi-Solid Casting of Pure Magnesium
Authors: Curle Ulyate Andries , Wilkins Jeremias D.
Published: January 2019

Semi-solid processing works on the principal of a solidification temperature interval of a substance. The substance is heated to a temperature within this interval so that there exists a related solid-liquid fraction ratio. The substance with this phase structure is then shaped by a forging or casting process. It has been stated before that it is impossible to semi-solid process and cast pure metals or eutectic alloys due to their thermodynamic temperature invariance, meaning that there is no temperature interval. It was demonstrated recently that it is possible to semi-solid casting high purity aluminium (Curle UA, Möller H, Wilkins JD. Scripta Materialia 64 (2011) 479-482) and the Al-Si binary eutectic (Curle UA, Möller H, Wilkins JD. Materials Letters 65 (2011) 1469-1472). The working principal is that there exists a time interval during thermal arrest during which solidification takes place with a solid-liquid fraction ratio until all the liquid is consumed upon cooling. The aim with this work is to demonstrate that pure magnesium can also be rheo-high pressure die cast (R-HPDC) with the system developed at the CSIR in South Africa. Magnesium is notoriously difficult to cast due to the thermal properties of magnesium. The metal was poured into a cup, processed for about 6 seconds after which it was HPDC into a plate. The microstructure of the casting consists of a structure that was solid and a structure that was liquid during thermal arrest at the time of casting.
Variation of Properties in the Cross-Section of Semi-Solid Al-7Si-0.3Mg Castings
Authors: Santos Jorge , Jarfors Anders E.W. , Dahle Arne K.
Published: January 2019

In semi-solid casting, a slurry consisting of primary α-Al crystals and liquid is injected into the die cavity. The solidification in the die-cavity occurs by the growth of the primary α-Al crystals formed during slurry preparation and in the shot sleeve, nucleation and growth of in-cavity solidified crystals and ends with the eutectic reaction. During solidification in the die cavity, the cooling rate near the die wall is higher in comparison to the centre of the casting, particularly for thick-walled castings. The solidification conditions for the slurry α-Al crystals that are closer to the die wall can be very different compared to the slurry α-Al crystals located at the casting centre. This can result in different solute concentration in the interior of the α-Al globules in different regions of the semi-solid casting cross-section and consequently, different response to heat treatament. The RheoMetal™ process was used to produce thick-walled semi-solid castings. Semi-solid castings in the as-cast and T6 conditions were investigated. Indentation tests for hardness measurements in the nano-range were performed in the interior of α-Al globules near the surface and at the casting cross-section centre. The hardness variation across the casting cross-section was evaluated by low-force Vickers hardness. The castings in the as-cast condition showed more uniform properties in the cross-section compared to the T6 condition. Additionally, the results suggest that microsegregation in the interior of α-Al globules is very low in castings in the as-cast and T6 conditions.
Application of the Correlation between Hardness and Strength in Conventional Al Alloys into Semi Solid Processed Products
Authors: Du Kang , Qu Wen Ying , Jing Yan Hong , Zhu Qiang
Published: January 2019

In the field of material production and application, strength and hardness are the two most common properties of metallic materials. It’s one familiar phenomenon that the hardness of one certain alloy has positive relationship with its strength in conventional dendritic alloys. When it comes to non-dendritic semi-solid alloys, it’s unclear that the relationship is still right or not. In this paper, the molecular mechanics, as well as finite element simulation and experimental verification were combined to study the internal deformation regularity of metallic material and the correlation between the two parameters was illustrated. Firstly, the displacement of solid atom in metallic crystal cell was well described in the view of energy cost. Secondly, the total strain amount under local indenting deformation (resistant boundary) and overall impressing deformation (free boundary) were compared to study the correlation between hardness and compression strength in semi-solid globule grain alloy. Finally, the data collected in semi-solid processed products was applied to be compared against traditional casting and wrought aluminum alloys.
Cutting Edge: HDAC3 Protects Double-Positive Thymocytes from P2X7 Receptor–Induced Cell Death
Authors: Philips Rachael L. , McCue Shaylene A. , Rajcula Matthew J. , Shapiro Virginia S.
Published: January 2019

Intricate life-versus-death decisions are programmed during T cell development, and the regulatory mechanisms that coordinate their activation and repression are still under investigation. In this study, HDAC3-deficient double-positive (DP) thymocytes exhibit a severe decrease in numbers. The thymic cortex is rich in ATP, which is released by macrophages that clear apoptotic DP thymocytes that fail to undergo positive selection. We demonstrate that HDAC3 is required to repress expression of the purinergic receptor P2X7 to prevent DP cell death. HDAC3-deficient DP thymocytes upregulate the P2X7 receptor, increasing sensitivity to ATP-induced cell death. P2rx7/HDAC3-double knockout mice show a partial rescue in DP cell number. HDAC3 directly binds to the P2rx7 enhancer, which is hyperacetylated in the absence of HDAC3. In addition, RORγt binds to the P2rx7 enhancer and promotes P2X7 receptor expression in the absence of HDAC3. Therefore, HDAC3 is a critical regulator of DP thymocyte survival and is required to suppress P2X7 receptor expression.
A Pass-By Noise Prediction Method Based on Source-Path-Receiver Approach Combining Simulation and Test Data
Authors: Calloni Massimiliano , Musser Chadwyck , Castel Alexis , Mejdi Abderrazak , Medeiros Augusto
Published: January 2019

Optimizing noise control treatments in the early design phase is crucial to meet new strict regulations for exterior vehicle noise. Contribution analysis of the different sources to the exterior acoustic performance plays an important role in prioritizing design changes. A method to predict Pass-by noise performance of a car, based on source-path-receiver approach, combining data coming from simulation and experimental campaigns, is presented along with its validation. With this method the effect of trim and sound package on exterior noise can be predicted and optimized.
Parents as Teachers: Teaching Pediatrics Residents the Art of Engaging in Difficult Conversations
Authors: Wilson Alexandra , Hurwitz Craig A. , Smith Monica , Patino Tracy , Kudalmana Arya S. , Gallas Michelle
Published: January 2019

Background 

Physicians often lack the skills and confidence needed to have difficult conversations with patients and their families. Patients and families who have experienced these conversations can provide valuable insight for resident physicians.

Objective 

We developed a communication skills workshop for pediatrics residents using parents and a team of social workers, nurses, chaplains, and physician facilitators in role-playing exercises.

Methods 

From 2007 to 2016, half-day “difficult conversation” workshops were held annually for postgraduate year 1 (PGY-1) and PGY-2 residents that included an interprofessional team and parents of children with life-threatening diagnoses. Questionnaires assessed residents' prior training, effectiveness of the sessions, and narrative feedback on the impact of this approach. Parents and team members were surveyed on the effectiveness of the training and the value of parent involvement.

Results 

Median self-reported confidence levels for incoming PGY-1 residents following the workshop rose from 2 to 4 on a 5-point Likert scale (99% response rate [128 of 129 surveyed], P < .001). The majority of PGY-2 residents (91%, 115 of 126) reported the workshop increased their confidence in engaging in difficult conversations (91% response rate [126 of 139]). Parents and clinical care team members agreed that parents would likely be preferable to standardized actors for these types of role-playing exercises (84% response rate [37 of 44]).

Conclusions 

Involving patients' parents and an interprofessional team in role-playing scenarios was a well-received method for teaching residents how to engage in difficult conversations with patients and families, and improved their self-reported confidence when having these conversations.
Institutional convergence in Europe
Authors: Schönfelder Nina , Wagner Helmut
Published: January 2019

This paper applies the statistical concepts of σ-convergence and unconditional β-convergence to institutional development within several country groups hierarchized to the degree of European integration (e.g., euro area). Two sets of indicators are employed to measure institutional development: first, the Worldwide Governance Indicators, and second, the product market regulation indicator of the OECD and the Doing Business distance to frontier indicator of the World Bank. The authors can clearly confirm institutional β-convergence within the EU and its aspirants, which is mainly driven by the new Member States and acceding, candidate, and potential candidate countries. However, euro-area countries converge only in the area of product market and business regulation— not in the area of governance. In fact, the authors show evidence for β-divergence in rule of law within the first twelve euro-area members. Concerning σ-convergence, the results are less clear. Only the EU including the EU-aspirants reduced the cross-country variance in all aspects of institutional development.
Do economic and financial integration stimulate economic growth? A critical survey
Authors: Ehigiamusoe Kizito Uyi , Lean Hooi Hooi
Published: January 2019

The recent vote by Britain to quit the European Union (EU) and the political pressures in some member countries to exit the EU necessitates a critical evaluation of the long-run economic benefits of economic integration or union to member countries. Consequently, this paper examines recent empirical studies on the nexus between economic integration and economic growth in developed and developing countries. It also investigates the literature concerning the impact of financial integration on economic growth. Evidence from the study shows that although other views exist, there is overwhelming support for the growthenhancing effects of economic integration, albeit common currency adoption has an insignificant effect on economic growth. The channels through which economic integration exerts its influence on economic growth include capital accumulation, productivity growth, trade, and financial integration. However, the study shows that the impact of financial integration on economic growth is inconclusive. Based on the findings, the study draws some implications and policy options.
The “cholesterol paradox” among inpatients – retrospective analysis of medical documentation
Authors: Budzyński Jacek , Tojek Krzysztof , Wustrau Beata , Czerniak Beata , Winiarski Piotr , Korzycka-Wilińska Wanda , Banaszkiewicz Zbigniew
Published: January 2019

Introduction

There is evidence of positive relationships between cholesterol concentration and risk of cardiovascular diseases. However, higher mortality in patients with a low cholesterol level has been reported (the “cholesterol paradox”).

Material and methods

Medical records of 34 191 inpatients between 2014 and 2016 were reviewed and the relationships between total (TC), low-density lipoprotein (LDL-C) and high-density lipoprotein (HDL-C) cholesterol and triglyceride blood concentrations and all-cause in-hospital death and readmission within 14 and 30 days and 1 year were determined in univariate and multivariate analyses.

Results

Patients with TC in the lower quartile and LDL-C < 70 mg/dl had greater risk of the outcomes measured than individuals with a TC level in the remaining quartiles and LDL-C ≥ 70 mg/dl. Moreover, patients with TC in the highest quartile, OR (95% CI): 0.36 (0.13–0.99), p < 0.05, and LDL-C ≥ 115 mg/dl, OR (95% CI): 0.53 (0.37–0.77), p < 0.05, had the lowest all-cause in-hospital mortality. However, multivariate analysis using logistic regression and a Cox proportional hazard model showed no significant influence of blood lipid levels on the occurrence of the outcomes measured.

Conclusions

A significant effect of a “cholesterol paradox” linking better prognosis with higher blood lipid concentration was found only in univariate analysis but, after adjustment for clinical characteristics in multivariate analysis, the plasma lipid level had a neutral influence on the occurrence of the measured outcomes. This suggests that a low cholesterol level should be interpreted as a biomarker of illness severity.
Is miRNA-375 a promising biomarker for early detection and monitoring of patients with type 2 diabetes?
Authors: Patoulias Dimitrios
Published: January 2019

miRNAs are small, non-coding RNAs, functioning as negative suppressors of target gene expression. A significant proportion of the transcriptome is subject to miRNA modulation. A single miRNA determines the expression of hundreds of genes, while miRNAs are relatively stable in biological fluids. Thus, they have attracted scientific interest regarding their use as biomarkers for several diseases. miRNA-375 mainly influences β-cell function and insulin secretion. Several studies, primarily experimental, have assessed its role as a biomarker in type 2 diabetes, while recently obtained human evidence supports this potential role. Besides its diagnostic potential, miRNA-375 may also have therapeutic implications. In view of the growing epidemic of type 2 diabetes, there is an unmet need for identification of biomarkers for early recognition and monitoring of these patients. Long-term, prospective human studies are required to elucidate whether miRNA-375 can evolve as a key player in diagnosis and prognosis of type 2 diabetes.
Blood-brain barrier damage as a predictor of outcome in patients with purulent meningitis
Authors: Dreshaj Shemsedin , Shala Nexhmedin , Ponosheci Albina , Aliu-Bejta Ajete , Ajazaj-Berisha Lindita
Published: January 2019

Introduction

Purulent meningitis is a severe infection of the central nervous system caused by different bacteria and very often causes severe complications and high lethality. Since the disease still has unclear pathogenesis and high mortality, researchers and clinicians are focused on the influence of damage of the blood-brain barrier (BBB) and its subsequent impact on the outcome of purulent meningitis. The aim of this study was to investigate the albumin concentration and the albumin coefficient as the best parameters of BBB damage, and their influence on the outcome of patients with purulent meningitis.

Material and methods

The study was carried out by examining the hospitalized patients in the Clinic of Infective Diseases in Prishtina, Kosovo. Blood-brain barrier damage is evaluated by analyzing the dynamics of values of proteins, glucose and albumins, as well as by determining the BBB coefficient of damage.

Results

The data consistent with BBB damage in patients with purulent meningitis corresponded with disease outcome. Consequently, 56.97% of the patients who developed complications or died had very severe BBB damage. Patients with the mean value of albumin coefficient X = 46.5 ±27.23 g/l were at higher risk of developing complications (relative risk (RR) = 2.63; p < 0.0001) or having a lethal outcome (RR = 5.20; p < 0.0001). Patients with longer duration of pathological mean values of albumin coefficient were at higher risk of developing complications (RR = 3.11; p < 0.0001).

Conclusions

Our data suggest that BBB damage in patients with purulent meningitis correspond with disease outcome. The best predictors for outcome were albumin coefficient and albumin concentration in cerebrospinal fluid.
Preliminary report: one of the PD-1 gene variants may be a valuable marker for colorectal cancer
Authors: Lamami Yosra , Mesediyeva Roya , Arikan Soykan , Ercan Şeyda , Kıyan Hilal Fındık , Tatar Cihat , Nayci Ali Emre , Farooqi Ammad , Yaylim İlhan , Kiran Bayram
Published: January 2019

Introduction

Introduction: Programmed death-1 (PD-1), an important immunosuppressive molecule, plays a key role in tumor-cell-mediated immune escape. The present study aimed to investigate the role of PD-1.5 (C/T) gene polymorphisms on the susceptibility and progression of colorectal cancer (CRC).

Material and methods

In this study, the PD-1.5 C/T polymorphism was investigated in 99 CRC patients and 150 healthy individuals as controls by nested polymerase chain reaction-restriction fragment length polymorphism method

Results

The distributions of PD-1.5 (C/T) genotypes and alleles were in agreement with Hardy–Weinberg equilibrium in controls (p>0.05) but not in CRC patients (p=0.02). We found a statistical significance difference between CRC patients and controls for the genotypic distribution of PD-1.5(C/T) genotypes (p=0.003) and also for alleles (p=0.004). The patients who have T allele have increased according to the controls (p=0.001). The patients who have C allele with distance metastasis have increased heterozygous CT genotype of PD-1.5 (C/T) polymorphism than those with no metastasis (p<0.001). We also detected the increased CC genotype in patients who have angiolymphatic invasion (p=0.043). The patients who have mucineous component have increased frequency of T allele than those with the absence of mucineous component (p=0.023).

Conclusions

Our results have shown significant associations between PD-1.5 genotypes and CRC susceptibility and progression of the disease.
Efficacy and safety of endoscopic balloon dilatation of esophageal strictures without fluoroscopy: a pilot study
Authors: Dincer Mürşit , Akinci Muzaffer
Published: January 2019

Introduction

Esophageal strictures can be caused by malignancy, congenital stenosis, motility disorders or benign strictures. Endoscopic balloon dilatation is a simple procedure with low complication rates to treat gastrointestinal strictures. This study aims to analyze indications and results of balloon dilatation without fluoroscopy.

Material and methods

The patients who underwent pneumatic balloon dilatation (PBD) for esophageal stricture were included in the study. The demographic characteristics of the patients, indications for PBD, number of operations and complications were recorded.

Results

Twelve patients were included in this pilot study. The most common cause of esophageal strictures was malignancy. In this group, PBD was performed before stenting in the patients who were planned to receive neoadjuvant therapy, had locally advanced esophageal cancer or inoperable esophageal cancer, and complained of difficulty swallowing. Three patients underwent PBD due to achalasia. One of these patients underwent PBD 3 times due to recurrence of symptoms during the follow-up period. The success rate of PBD in this study was 91.6%. The success rate for the patients who underwent PBD for the first time was 83.3%. None of the patients who underwent endoscopic balloon dilatation had major complications (such as massive bleeding and perforation) or procedural mortality.

Conclusions

Endoscopic balloon dilatation without fluoroscopy performed by experienced endoscopists is an effective and safe method for the treatment of esophageal strictures. Successful results are obtained with low complication rates in experienced centers.