Thermal and Mechanical Properties Analysis of Age-Based Human Tooth Enamel

@#Introduction: As the important part of tooth, enamel must be treated well in order to keep its function. The purpose of study is provide tooth composition for various condition and at different ages. Methods: Children (1-2 years), adults (13-40 years), and parents (41-70 years) tooth, aquabidest, abrasive paper, tooth bor, caliper, trimmer, Machines for Hardness test, compressive test and XRD. Each test sample will be cut, mashed, washed and soaked in aquabidest in refrigerator and then to be examined. Results: Micro test results were showed that the main components of the teeth are Hydroxy apatite, Fluorine apatite, and Calcium phosphate hydrate. Transition glass occurs in the age range 1-12 years old at 340o C and in the age range 13-40 years old at a temperature of 400o C , however at the age of 41-70 years old at temperatures of 360o C based on the thermal test results, melting point and boiling point. Mechanical test was showed the level of violence has increased from the age of 1-40 years old then later has decreased, as well as for compressive strength. Hydroxy apatite, Fluorine apatite increase, and Calcium phosphate hydrate decreases in line with age. Tooth enamel also tends to be able to withstand heat in line with age. Conclusion: The level of hardness and tooth strength tends to increase temporarily in older people’s teeth as the calcium content decreases, thus its mechanical strength decreases.

Elaboración de productos tipo tallarín libres de gluten y evaluación de sus propiedades fisicoquímicas / Elaboration of gluten free noodle products and evaluation of its physicochemical properties

RESUMEN La creciente demanda de productos libres de gluten ha dado lugar al estudio y desarrollo de alimentos que suplan las necesidades de los consumidores. El objetivo de esta investigación fue elaborar productos libres de gluten tipo tallarín y evaluar sus propiedades fisicoquímicas. Para ello, se empleó plátano o yuca como fuentes alternativas a la harina de trigo. Se determinaron sus propiedades fisicoquímicas. Se extrajeron harina y almidones y, a partir de ellas, se evaluaron sus propiedades térmicas, empleando calorimetría de barrido diferencial y termogravimetría. Se formularon y elaboraron productos similares a los tallarines empleando las harinas y se analizaron sus propiedades fisicoquímicas, microbiológicas y sensoriales, usando, como control, un producto comercial de trigo. La yuca presentó mayor humedad que el plátano, lo que está relacionado con su susceptibilidad a la degradación. En el análisis termogravimétrico, los productos de yuca mostraron mayor reducción de peso en la zona de alta volatilidad, asociado a la pérdida de humedad. Las harinas y los almidones de plátano presentaron temperaturas de gelatinización mayores que las registradas para los productos de yuca. La humedad y acidez de los tallarines elaborados presentaron valores dentro de la norma (NTC 1055-2014). En ambos casos, su contenido de cenizas fue superior al fideo comercial. Los tallarines elaborados, se pueden considerar inocuos, con buenos parámetros de aceptación sensorial. Estos resultados constituyen un punto de partida en el estudio y aplicación de fuentes de harinas y almidones no tradicionales, permitiendo la generación de valor agregado a cultivos de importancia en la región.

ABSTRACT The growing demand of free gluten products has shown the necessity to study and develop new products in order to supply the consumer request. The objective of this research was to elaborate gluten-free products similar to noodles and to evaluate their physicochemical properties. Plantain or cassava were employed to replace wheat flour. Physical and chemical properties were determined in plantain and cassava samples. Both, Plantain and Cassava Flour and their starches were extracted. Thermal characteristics of flour and starch were evaluated employing differential scanning calorimetry and thermal gravimetric analysis. Products similar to noodle were formulated and elaborated employing plantain or cassava flour. Noodle physicochemical, microbiological and sensorial characteristics were analyzed, employing a commercial product as a control. Cassava presented higher humidity values than plantain, it is related to their susceptibility to degradation. In thermogravimetric analysis, cassava products shown upper weight reduction in high volatility zone associated to humidity lost. Plantain flours and starches presented gelatinization temperatures higher than registered for cassava products. Both plantain and cassava noodles presented humidity and acidity values according to the legal legislation (NTC 1055-2014). Developed products showed ash content higher than commercial noodles. According to microbiological and sensorial analyses, the plantain and cassava products could be considered innocuous with good consumer acceptation. These results could constitute a starting point in the study and application of different flours and starches from non-traditional sources, which allow to increase the value of crops in the region.

Chemical Composition of Abrus precatorius L. Seeds

Aims: A. precatorius seed powder is traditionally used in Ayurveda, Siddha and Unani medicine. The objective of present work is to describe the oil, starch, protein, polyphenol and mineral composition of A. precatorius seeds. Methodology: Legumes from A. precatorius were collected, and seeds were manually separated. Dried seeds in powder form were employed for the various analyses: solvent extraction was used for elucidation of the oil percentage value; starch content was determined by the enzymatic method; total polyphenol and flavonoid contents were spectrophotometrically analyzed using Folin-Ciocalteu and aluminum chloride as the color developing reagents, respectively; and X-ray fluorescence (XRF) was used for the mineral contents assessment. Results: The seed kernel consisted of stored oil (3.2%), protein (92.0%) and starch (4.8%). The total polyphenol and flavonoid contents were 24710 and 2520 mg/kg (dw). A remarkably high content of polyphenols was observed in the seed coat and the seed pod. P, S and (mainly) K nutrients were hyper-accumulated in the seed kernel. The seeds showed a glass transition at -21°C, two endothermic peaks at 109°C (dehydration and protein unfolding) and at 209°C, and a calorific value (~406 kcal/100 g dw) that exceeded those of Pisum sativum L., Lens culinaris Medik. and other common pulses. Conclusions: The seed kernel from A. precatorius was mainly composed of stored protein, with low oil and starch contents. High contents of polyphenols, K, Mg, Ca and Fe were found in the seeds. Heavy metals were below the safety limits established for human consumption.

Poly(3-hydroxybutyrate) graft copolymer dense membranes for human mesenchymal stem cell growth

Background: The use of novel materials as an artificial extracellular matrix for stem cell growth is a current strategy of increasing interest for regenerative medicine. Here, we prepare thermal-remolded membrane scaffolds from poly(3-hydroxybutyrate) grafted with 2-amino-ethyl methacrylate hydrochloride. However, it is unclear whether these membranes are useful for tissue engineering. Results: The mechanical properties, tribology, and morphology of the dense membranes were assessed. The results show that tensile strain at break and roughness of the compressed membrane decrease with increasing graft degree. Moreover, graft copolymer membranes showed lower resistance to scratching, greater degree of swelling and higher brittleness than un-grafted P(3HB) films. Thus, it effectively supports the growth of dermal fibroblast, as demonstrated by epifluorescence microscopy. Conclusions: It is concluded that the developed membrane can be properly used in is the restoration of skin tissue. How to cite: González-Torres M, Sánchez-Sánchez R, Solís-Rosales SG, et al. Poly(3-hydroxybutyrate) graft copolymer dense membranes for human mesenchymal stem cell growth.

Effects of surface proteins and lipids on molecular structure, thermal properties, and enzymatic hydrolysis of rice starch

Abstract Rice starches with different amylose contents were treated with sodium dodecyl sulfate (SDS) to deplete surface proteins and lipids, and the changes in molecular structure, thermal properties, and enzymatic hydrolysis were evaluated. SDS treatment did not significantly change the molecular weight distribution, crystalline structure, short-range ordered degree, and gelatinization properties of starch, but significantly altered the pasting properties and increased the swelling power of starch. The removal of surface proteins and lipids increased the enzymatic hydrolysis and in vitro digestion of starch. The influences of removing surface proteins and lipids from starch on swelling power, pasting properties, and enzymatic hydrolysis were different among the various starches because of the differences in molecular structures of different starch styles. The aforementioned results indicated that removing the surface proteins and lipids from starch did not change the molecular structure but had significant effects on some functional properties.

04-7 Thermal profile of three clays suitable to be used as solid components in the preparation of peloids / 日本温泉気候物理医学会雑誌

  There is little doubt that the main therapeutic action of the peloid’s, therapy depends on their thermal properties. For this reason is quite of interest getting to know the thermal properties of the materials that form peloids. Objective: Study the thermal properties of three inorganic solids that can be used in the preparation of therapeutic peloids. Materials and Method: The products used are aluminic Bentonite, Kerolita (Süd Chemie) and SPLF ELITE (Tolsa).   From the thermal point of view the specific heat was determined using a Scanning Calorimetry equipment, model DSC1, cooled by air of Mettler Toledo and it was used the software STARe for the collection and processing of data.   An extemporaneous product was prepared with a liquid phase of 60%, using distilled deionized water. Its cooling curves their relaxation and inertia times were studied.   For the determination of the cooling curves we have followed the Rambaud technique, obtaining graphs and equations that best fit the experimental curve, using the ORIGIN program 8. We used Thermostatic baths, models Lauda RA Alpha 8 and E-100 and a thermocouple Cole-Parmer, model 91100-50. Results and Discussion: The following Table 1 shows the results of the specific heat measures of the three studied products, in the range of 45-36°C and its corresponding average value. We also include the inertia and relaxation time of peloids. Conclusions: The SPLF, a sepiolite, presents the highest value of the specific heat, whose corresponding peloid with an equal percentage of water would provide the greatest amount of heat. The specific heat of the bentonite and kerolita is very similar.   Bentonite Al shows the most relaxation time of the three products, releasing therefore the heat more slowly.

04-7Thermal profile of three clays suitable to be used as solid components in the preparation of peloids / 日本温泉気候物理医学会雑誌

  There is little doubt that the main therapeutic action of the peloid’s, therapy depends on their thermal properties. For this reason is quite of interest getting to know the thermal properties of the materials that form peloids.<BR><b>Objective: </b>Study the thermal properties of three inorganic solids that can be used in the preparation of therapeutic peloids.<BR><b>Materials and Method: </b>The products used are aluminic Bentonite, Kerolita (Süd Chemie) and SPLF ELITE (Tolsa). <BR>  From the thermal point of view the specific heat was determined using a Scanning Calorimetry equipment, model DSC1, cooled by air of Mettler Toledo and it was used the software STARe for the collection and processing of data.<BR>  An extemporaneous product was prepared with a liquid phase of 60%, using distilled deionized water. Its cooling curves their relaxation and inertia times were studied.<BR>  For the determination of the cooling curves we have followed the Rambaud technique, obtaining graphs and equations that best fit the experimental curve, using the ORIGIN program 8. We used Thermostatic baths, models Lauda RA Alpha 8 and E-100 and a thermocouple Cole-Parmer, model 91100-50.<BR><b>Results and Discussion</b>: The following Table 1 shows the results of the specific heat measures of the three studied products, in the range of 45-36°C and its corresponding average value. We also include the inertia and relaxation time of peloids.<BR><b>Conclusions: </b>The SPLF, a sepiolite, presents the highest value of the specific heat, whose corresponding peloid with an equal percentage of water would provide the greatest amount of heat. The specific heat of the bentonite and kerolita is very similar. <BR>  Bentonite Al shows the most relaxation time of the three products, releasing therefore the heat more slowly.

Mechanical and thermal properties of polyamide versus reinforced PMMA denture base materials

PURPOSE: This in vitro study intended to investigate the mechanical and thermal characteristics of Valplast, and of polymethyl methacrylate denture base resin in which different esthetic fibers (E-glass, nylon 6 or nylon 6.6) were added. MATERIALS AND METHODS: Five groups were formed: control (PMMA), PMMA-E glass, PMMA-nylon 6, PMMA-nylon 6.6 and Valplast resin. For the transverse strength test the specimens were prepared in accordance with ANSI/ADA specification No.12, and for the impact test ASTM D-256 standard were used. With the intent to evaluate the properties of transverse strength, the three-point bending (n=7) test instrument (Lloyd NK5, Lloyd Instruments Ltd, Fareham Hampshire, UK) was used at 5 mm/min. A Dynatup 9250 HV (Instron, UK) device was employed for the impact strength (n=7). All of the resin samples were tested by using thermo-mechanical analysis (Shimadzu TMA 50, Shimadzu, Japan). The data were analyzed by Kruskal-Wallis and Tukey tests for pairwise comparisons of the groups at the 0.05 level of significance. RESULTS: In all mechanical tests, the highest values were observed in Valplast group (transverse strength: 117.22 +/- 37.80 MPa, maximum deflection: 27.55 +/- 1.48 mm, impact strength: 0.76 +/- 0.03 kN). Upon examining the thermo-mechanical analysis data, it was seen that the E value of the control sample was 8.08 MPa, higher than that of the all other samples. CONCLUSION: Although Valplast denture material has good mechanical strength, its elastic modulus is not high enough to meet the standard of PMMA materials.

Poly (l-lactide acid) improves complete nano-hydroxyapatite bone scaffolds through the microstructure rearrangement

Cracks often occur when nano-hydroxyapatite bone scaffolds are fabricated with selective laser sintering, which affect the performance of scaffolds. In this study, a small amount of poly (l-lactide acid) (PLLA) was added into nano-hydroxyapatite (nano-HAP) powder by mechanical blending in order to improve the sintering properties. The nano-HAP powder combined with 1wt percent PLLA was sintered under different laser power (5W, 7.5W, 10W, 12.5W, 15W and 20W). The fabricated scaffolds were characterized using Scanning Electron Microscope (SEM), X-ray Diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and Micro Hardness Tester. The results showed that nano-HAP particles grew up quickly with the laser power increasing, and there were many strip-like cracks on the surface of sintering zone. The cracks gradually reduced until disappeared when the laser power increased to 15W, together with a great improvement of density. Large pores were observed on the specimen when the laser power further increases, accompanied with the decomposition of HAP into β-tricalcium phosphate (β-TCP) and tetracalcium phosphate (TTCP). And the optimum parameters were eventually obtained with laser power of 15W, scanning speed of 1000 mm/min, powder bed temperature of 150ºC, laser spot diameter of 2 mm and layer thickness of 0.2 mm. We summarized that the molten PLLA enhanced the particle rearrangement of nano-HAP by capillary force and may absorb thermal stress in laser sintering process, while PLLA would be oxidized gradually until completely excluded from the sintered nano-HAP scaffolds, which was confirmed by FTIR analysis. This study provides a novel method to improve the sintering properties of nano-HAP with no adverse effects which would be used in the application of bone tissue engineering potentially.

Transformation Behaviour, Bending Properties and Surface Quality of 22 Commercial Nickel- Titanium Wires: A Batch-to-Batch Evaluation.

Aims: The aims of this study were to investigate batch-to-batch differences in mechanical and thermal properties of 22 commercial nickel-titanium wires and evaluate the surface quality. Secondly the percentages of superelasticity at mouth temperature were measured. Study Design: In vitro laboratory study. Place and Duration of Study: Sample: Department of Oral Health Sciences – Orthodontics and Metallurgy and Materials Engineering KU Leuven, between January 2010 and May 2011. Methodology: The sample comprised 22 NiTi wires of the upper jaw from 7 different manufacturers. For each brand two different batches were investigated (LOT A, LOT B). Three different investigations were carried out. First transformation behaviour and transition temperatures were determined by differential scanning calorimetry, second a three point bending test was done to evaluate the mechanical properties and third scanning electron microscopy was performed on all samples to evaluate surface quality. Results: Absolute batch-to-batch differences in the investigated properties were all deviating from zero, although most differences were clinically acceptable. Significant interbatch differences in thermal properties were found in 4 wires. Mechanical interbatch differences were found remarkable for 5 wires. Percentage of elasticity showed a non- superelastic curve below a deflection of 1500 μm, which represents clinical small deflections. Surface topography showed also interbatch differences for 4 wires. Conclusion: This study shows that batch-to-batch differences are obvious in each sample. One has to be careful in the selection of archwires. Therefore more standardized consument information should be provided.