Optical and Electronic Microscope for Minero-Petrographic and Microchemical Studies of Lime Binders of Ancient Mortars

In this paper, the advances in the use of optical and electronic microscope for study of the minero-petrographic and microchemical features of lime binders of ancient mortars are discussed for various case studies. Mortars belonging to several historic periods and with different functions in building structures and archaeological sites were selected in order to verify the complementarity of optical and electronic microscope analyses applied to these artificial materials. The data obtained with the application of optical and microscope analyses were able to provide detailed and more precise information on the composition, structure, and texture of lime binders, highlighting the features of air hardening calcitic lime binder, air hardening magnesian lime binder, natural hydraulic lime binder, and air hardening binders with materials providing hydraulic characteristics added. Furthermore, a complete analysis and classification of the lime lumps was determined.

Cotton canvas trousers washing: an inception of a new horizon in apparel industry

Nowadays, fashionable trouser (denim) with washing effect is very popular, especially among the youth. The global fashion trend has led to the development of diverse washing processes that are predominantly applied to denim fabric. However, no known research has studied the application of the washing effect on canvas fabric. Therefore, this paper aims to make fashionable canvas fabric trousers by applying various washing effects. To do so, ready-to-dye canvas fabric trouser was constructed, then dyed with dischargeable reactive dye (Lava). Chemical washing processes such as whisker, enzyme, and PP spray were then applied on dyed canvas trousers. Finally, developed samples were being characterized by mechanical tests such as tensile strength, tear strength, stiffness, abrasion, pilling, colorfastness to wash, and colorfastness to rubbing. Besides, to evaluate fabric surface, various tests such as Scanning Electronic Microscope (SEM), Reflectance% values have also been characterized. Tensile strength, tear strength, stiffness, reflectance% value, and wear index% changed significantly for every subsequent process. The tensile strength of finished trousers was 489.87 N at warp and 350.57 N at weft direction and the tear strength was 48.01 N and 35.56 N at warp and weft direction, respectively. The reflectance% value of 18.74 was observed at the PP sprayed area. Overall, the research revealed the possibility of using cotton canvas as a pair of fashionable trousers contributing to the development of the apparel industry.

Preloading Effect On The Strength of Cement Mass Mixing Treated Salty Sand

Existing problematic sub-layers in mixing technologies are a challenge, and for the first time, the effects of salt sub-layers in mass mixing technology have been investigated in this study for sandy salt in the southwest of Iran. This paper discusses the influence of adding various cement contents, Aw, and imposing different preloading values on the salty sand soil. First, salt and sand samples were dried, then, 90 % sand was mixed with 10% salt. After that, 30 % water was mixed thoroughly with the mixture of salty sand to obtain slurries. Cement slurry at a water-cement ratio (w/c) of 0.6 was then added to the sample and thoroughly mixed. The amount of cement in a slurry form that was added to the salty soil was 2, 4, 6, 8, and 10% by mass of dry soil. Each treated soil preloaded by 0, 9, and 45 kPa. After 120 days, the unconfined compressive strength of the sample was determined. Furthermore, by Scanning Electronic Microscope, SEM, the microstructures of treated samples were analyzed. At the end Unconfined Compression Strength, UCS, test results normalized to the non-preloaded treated soil. By increasing cement content, the effect of preloading in increasing UCS will decrease. In the SEM images for Aw=2%, the effect of preloading indicates porous shape for non-preloaded samples. Vice versa by Aw=8%, porous shape in the SEM images will disappear. In the end, treatability studies of pure salt in the thick layer have been investigated.

Creating a Material Spectral Library for Plaster and Mortar Material Determination

Historic object analysis and the knowledge of composition play an important role in restoration processes. Based on this information, restoration works are conducted. This paper introduces a non-invasive technique of plaster and mortar material decomposition using reflectance spectroscopy. For this purpose, a NIRQuest512-2,5 from Ocean Optics®/Ocean Insight®, is used to create a unique spectral library consisting of various materials. They were carefully selected to include those that were and still are commonly used for a plaster and mortar production. Each material of the spectral library was mapped in detail, verified using scanning electronic microscope (SEM) data, and the results were compared to a previously determined spectral signature. The new spectral library was then tested on 11 unknown plaster and mortar samples and verified using a scanning electronic microscope. It was found that reflectance spectroscopy provides a powerful tool for plaster and mortar material decomposition, although at the moment it cannot fully replace invasive techniques like chemical analyses or other invasive techniques. It provides relevant information that can be used for restoration works.

The Influence of Three Different Digital Cement Spacers on the Marginal Gap Adaptation of Zirconia-Reinforced Lithium Silicate Crowns Fabricated by CAD-CAM System

Background: This study compared the influence of three different radial spacers (60,90,120 microns) on the marginal gap adaptation by using computer-aided manufacturing (CAD-CAM) for producing monolithic zirconia reinforced lithium silicate (ZLS) ceramic crowns. Methods: A total of 45 abutment acrylic teeth were divided into three groups of different radial spacers (60, 90, and 120 microns). In each group 15 teeth were scanned by Omnicam intra oral scanner and ZLS crowns were ground. For each unit the marginal gap was evaluated at four regions of interest by scanning electronic microscope (SEM). To compare the marginal gap between the three groups a one-way ANOVA with post-hoc Bonferroni test was preformed (α = 0.05). Results: The marginal gap for a 60 microns (162.99 ± 16.25 µm) radial spacer was found significantly higher than 90 (41.85 ± 3.57 µm) and 120 (41.85 ± 5.3 µm) microns radial spacers (p < 0.05). Between 90- and 120-micron radial spacers no difference was obtained. (p < 0.05). Conclusions: A radial spacer of 60 microns showed a significantly higher marginal gap compared to 90 and 120 microns and was not clinically accepted (>120 microns). For both 90 and 120 microns the marginal gap was clinically accepted (<120 microns) with no difference between the groups. The radial spacer which should be optimum for CELTRA® DUO crowns is 90 microns.

Cyclic fatigue resistance of four different nickel-titanium instruments in an artificial canal

Introduction: The objective of this study was to measure the number of cycles to fracture of four continuous or reciprocating rotary nickel-titanium instruments in different materials. Methods: A total of 40 nickel-titanium instruments were used for the present study. Instruments were divided into four groups (n=10): group 1, Revo-S SU; group 2, ProTaper Next X2; group 3, Reciproc R25; group 4, WaveOne Gold Primary. An artificial stainless-steel was used to test the cyclic fatigue of the instruments. The instruments were introduced into the stainless-steel canal, one at a time, until they reached the other end, then they were rotated inside the canal without in-out motion. The time from the beginning of instrument rotation until the occurrence of breakage was recorded. The number of rotated cycles to fracture of the instrument were calculated based on the revolutions per minute (rpm) of each instrument and the recorded rotated time. The mean number of cycles to fracture and standard deviations were calculated and statistically analysed. Results: The number of cycles to fracture of the Revo-S SU was the lowest, and that of the WaveOne Gold Primary was highest. Scanning electronic microscope images of fracture surfaces revealed the characteristics of fatigue. Conclusions: The number of cycles to fracture of the reciprocating WaveOne Gold Primary system was the highest amongst the tested instruments.

Phase Transformation of Alumina, Silica and Iron Oxide during Carbothermic Reduction of Fly Ash for Ceramics Production

Fly ash is a by-product from burning of coal. Utilization of fly ash by carbothermic reduction is an effective way to recover aluminum, silicon, and iron to enhance product-added value. This work is focused on the phase transformation of Al2O3, SiO2 and Fe2O3 during carbothermic reduction of fly ash in air. A comparative analysis of carbothermic reduction of fly ash in air and in nitrogen was made. Thermodynamics analysis was performed to illustrate the possible reactions for residue and condensate. X-ray diffraction (XRD), scanning electronic microscope (SEM), and energy dispersive spectrometry (EDS) were employed to characterize the phase composition, surface morphology, and microstructure of the reduced products. Results show that Fe3Si and Fe2Si appear sequentially with increasing of temperature. Al5O6N is an intermediate compound. Residue of Al9FeSi3, Al, and Si, and condensate of SiC, AlN and C are obtained. β-SiAlON was not found in the residue. Nitrogen is involved in the reduction of Al2O3 but not in the reduction of SiO2 and Fe2O3. Carbothermic reduction of fly ash in air did not behave the same as fly ash in nitrogen.

A new species of Litarachna Walter, 1925 (Acari: Hydrachnidia: Pontarachnidae) from Corozal Bay (Belize), described based upon morphology and DNA barcodes

A new planktonic species of the marine water mites of the family Pontarachnidae Koenike, 1910 is described from Corozal Bay, an estuarine system in Belize. The morphological description includes Scanning Electronic Microscope (SEM) images and is augmented by an analysis of DNA cytochrome c oxidase I (COI) sequences, the DNA barcode, used for the first time for a species description in this group.

RESEARCH of ELASTOMERS properties BASED ON COMBINATION OF ISOPRENE AND NITRILE BUTADIENE RUBBERS

Применение резинотехнических изделий в крайних условиях Севера ставит ряд научно-технических проблем, связанных с их надежностью и безотказностью. Основной причиной выхода из строя техники вовремя эксплуатации при низких отрицательных температурах является потеря работоспособности уплотнительных резин по причине низкой морозостойкости. Одним из способов решения данной проблемы является разработка резиновых смесей на основе двух или более каучуков, обладающих высокимизначениями морозо- и агрессиво- стойкости. В работе приведены результаты исследования эластомеров на основе комбинации изопренового каучука марки СКИ-3 и бутадиен-нитрильного каучука марки БНКС-18. В результате проведённых исследований установлено, что при разных соотношениях каучуков СКИ-3 и БНКС-18 в резиновой смеси происходит изменение упруго-прочностных свойств эластомеров, стойкости к углеводородным средам, модуля упругости, твердости, плотности, остаточной деформации сжатия и износостойкости. При исследовании на дифференциально-сканирующем калориметре были выявлены две температуры стеклования у резин на основе комбинации каучуков. При помощи электронного микроскопа были получены снимки в объеме образцов, на которых наблюдается фазовая морфология резин, которая в зависимости от соотношения каучуков в смеси более характерна для бутадиен-нитрильного или изопренового каучуков. Также отмечено, что поверхность трения резины на основе БНКС-18 обладает наиболее шероховатойструктурой по сравнению с резиной с большим содержанием каучука СКИ-3. The use of rubber products in the extreme conditions of the North creates a number of scientific and technical problems associated with their trustworthiness and reliability. The main reason of equipment failure during operation at low negative temperatures is the performance loss of sealing rubbers due to low frost resistance. One of the ways to solve this problem is the development of rubber compounds based on two or more types of rubber with high values ​​of frost and aggression resistance. This article presents research results of elastomers based on a combination of isoprene rubber IR and nitrile butadiene rubber NBR. As a result, it was discovered that at different ratios of IR and NBR rubbers in a rubber compound, there is a change in the elastic-strength properties of elastomers, resistance to hydrocarbon media, elastic modulus, hardness, density, residual compression deformation and wear resistance. In the research of differential scanning calorimeter, two glass transition temperatures were identified as rubbers based on a combination of rubber. Using electronic microscope, images were obtained in the volume of samples, which is the phase morphology of rubbers is observed, which is depending on ratio of rubber in the mixture is more specific for nitrile butadiene or isoprene rubber. It was also noted that the friction surface of rubber based on NBR has the roughest structure compared to rubber with a high content of IR rubber.

Effect of fiber orientation on the tensile properties of cross-ply laminates of PP reinforced continuous carbon fiber

This paper presents an experimental study of tensile properties, using a carbon–polypropylene uni-directional sheet with a thickness of 0.15 mm, which shows that highly non-linear stress–strain curves can be achieved with cross-angle-ply laminates. Generally, these properties are studied from the scanning electronic microscope and X-ray computed tomography. Cross-ply laminates with fiber orientation angles from 15 to 60° are investigated and it is found that there are the pseudo-ductile behavior with the fiber rotation, especially at fiber orientation angles from 30° to 60°.The Pseudo-ductile behavior is a phenomenon in which the apparent strain increases after yielding with strain hardening. It is greatly affected by the fiber reorientation in the loading direction. The fiber reorientation is allowed the plasticity of the polypropylene and thickness of each layer.