Heating Time Duration Research Articles

Fluorimetric determination of aqueous formaldehyde employing heating and ultrasound-assisted approach through its derivatization with a ß-diketone-nickel(2+) complex immobilized in a PMMA flow cell

Formaldehyde (FA) is a highly toxic substance present in many matrices, including freshwater as well as found in natural mechanisms such as rainfall and combustion of organic matter. Consumption of water contaminated with high levels of FA can cause severe short-term or long-term health problems. Due to these health risks, procedures are necessary to determine and quantify FA in aqua sources This paper reports on a study of fluorimetric determination of FA using a nickel(2 + )-diketonate coordination compound immobilized as a solid precursor. The compound was characterized by electronic absorption, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), thermogravimetry (TG), optical microscopy (OM), and scanner electron microscopy (SEM). The methodology was based on the reaction of the synthesized compound with an ammoniacal buffer generating a selective reagent for formaldehyde: fluoral-P. The product of the reaction generates 3,5-diacetyl-1,4-dihydrolutidine (DDL), which is responsible for the fluorescence of the system. Several parameters such as temperature, duration of heating time, and dilution effect with the best effects were studied to carry out FA determination. Under the optimum experimental conditions, a linear response ranging from 1.0 to 10.0 mg/L FA (R = 0.997 and n = 10), and a detection (3σ criterion) and quantification (10 σ criterion) limit estimated at 0.129 and 0.389 mg/L, respectively were achieved. The FA analysis was able to be conducted in 05 min with a relative standard deviation estimated at 1.10 %.

Experimental study on post-fire properties of steel wires of bridge suspender

This paper presents an experimental study on the post-fire static and fatigue properties of steel wires, which is the basic component of bridge suspender. In these tests, the effect of exposure temperatures, duration of heating time, cooling methods and prestress in steel wires during heating process was investigated. It is observed that the residual strengths (including static and fatigue strengths) of steel wire specimens were highly related to the maximum temperature reached during the heating process, and when the maximum temperature exceeds 400 °C, more significant reduction in residual strengths could be caused by higher maximum temperature. By analyzing the residual strength of the specimens applied with different prestresses, it is found that the prestress has an adverse effect on the residual strength. In addition, through electron microscope scanning, the mechanism of the material degradation under fire attack was analyzed and discussed. The findings of this study can be used to evaluate the extent of damage due to fire attack and provide guidance for maintenance or repair strategy.

Accelerated crystallization of CuAlO2 delafossite phase by controlling thermal regime during solution combustion synthesis

In the present study, for the first time, CuAlO2 delafossite phase was successfully obtained through a one-step solution combustion synthesis (SCS) process. Moreover, in order to accelerate CuAlO2 crystallization, two-step process, i.e. SCS followed by heat-treatment (different thermal regimes: continuous and discontinuous) without controlling the atmospheric oxygen, was applied. In the two-step process, heating time duration needed for the crystallization of CuAlO2 was lowered to 30 min at 1100 °C by exerting SCS on the mixture of starting materials. It was found that different thermal regimes can highly affect the formation of CuAlO2 phase. Furthermore, according to the SEM and TEM studies, it was revealed that the resultant powders have a flaky-shape morphology with lamellar structure.

Cranberry Beans Derived Carbon Dots as a Potential Fluorescence Sensor for Selective Detection of Fe3+ Ions in Aqueous Solution.

Recently, synthesis, characterization, and application of carbon dots have received much attention. Natural products are the effectual carbon precursors to synthesize carbon dots with fascinating chemical and physical properties. In this study, the fluorescent sensor of carbon dots derived from cranberry beans without any functionalization and modification was developed. The carbon dots were prepared with a cheap, facile, and green carbon precursor through a hydrothermal treatment method. The synthetic process was toxic chemical-free, convenient, and environmentally friendly. To find the optimized synthetic conditions, the temperature, heating time duration, and carbon precursor weight were evaluated. The prepared carbon dots were characterized by UV light, transmission electron microscopy, Raman, Fourier transform infrared, UV–vis, and fluorescence spectroscopy. The resulting carbon dots exhibit stable fluorescence with a quantum yield of approximately 10.85%. The carbon dots emitted the broad fluorescence emission range between 410 and 540 nm by changing the excitation wavelength and were used for the detection of Fe3+ ions at the excitation of 380 nm. It is found that Fe3+ ions induced the fluorescence intensity quenching of the carbon dots stronger than other heavy metals and the Fe3+ ion detection can be achieved within 3 min. Spectroscopic data showed that the obtained carbon dots can detect Fe3+ ions within the wide concentration range of 30–600 μM with 9.55 μM detection limit.

Changes in HMF content and diastase activity in honey after heating treatment

Like any other food items which are placed for sale, honey is one of them; therefore, its freshness is a matter of concern. Beekeepers usually use heat crystallized honey to make it more captivating to consumers. In this process honey is heated to degrade fructose to hydroxymethylfurfural (HMF). Heating also deactivate daistase enzyme in honey. This research is focused on enzyme degradation and estimation of changes in HMF content of honey (multi-floral & acacia) due to thermal treatment performed at 4°C, 25°C, 35°C, 45˚C and 55˚C temperatures for 4 and 8 hours. Both these quality parameters are one of the important indicators for freshness, storage and proper heating of honey. The samples of Multi-floral honey were collected from beekeepers of distinct areas of Punjab. Results were subjected to Statistical analysis. It was found that except 4°C and 25°C, the other temperatures caused rising of HMF content and lowering in diastase activity with different ratio depending upon duration of heating time. Keywords: Diastase activity; European bee; Pakistani honey; Thermal treatment http://dx.doi.org/10.19045/bspab.2019.80109

Causes and Control Mechanism of Abnormal Structure in the Center of SWRH82B Wire-Rod-Steel

The cause of drawing fracture of SWRH82B wire rods was analyzed by using optical microscopy, scanning electron microscope - energy dispersive spectrometer and electron probe micro-analyzer - wavelength dispersive spectrometer. A multivariate diffusion model was established in Thermo-Cale, and the effects of temperature and time on diffusion behavior of alloys were studied. Results show that cementite network and martensite in the center area of rod is main cause of tensile fracture. There is serious segregation of chromium and manganese in the central area. The CCT curve moves to right, and critical cooling rate of martensite decreases. With high cooling rate, time for eutectoid transition is insufficient, and martensite transformation occurs in segregation band. The segregation of phosphorus further worsen the brittleness of steel. With increase of heating temperature and duration of heating time, segregation in final product is reduced, and content of cementite network and martensite decreases. When the temperature is maintained at 1050 °C for 600 s, there is no segregation of phosphorus and carbon. The diffusion of chromium is even when temperature is maintained at 1150 °C for 5400 s, and an even diffusion of manganese is obtained when temperature is maintained at 1200 °C for 3000 s. In stelmor air cooling process, the key point is keeping cooling rate low to extend holding time, and to optimize microstructure and properties.

ANALISA PENGARUH SUHU DAN WAKTU PEMANASAN PADA NYLON FILM TERHADAP MAMPU BENTUK ZIPPER

Ultrasonic Welding has been used to join the thermoplastic material of about 35 years. Now, Ultrasonic Welding has been widely used not only for the thermoplastic material, but also can be used for all kinds of industries, one of which is the textile industry. Ultrasonic Welding has many advantages economically and efficiency. In its use of the zipper industry, Ultrasonic Welding used to join between components to the surface of the film nylon zipper. However, the wrong calculation of the temperature and the length of time could caused the strength of nylon films was reduced to cause permanent damage. This study aims to determine the temperature and duration of heating time. Ultrasonic Welding is used Branson type with power supply 40 kHz / 60 W with a maximum current of 3A. Booster type used is standard series M8 x 1:25 Horn 40 kHz with titanium material. Converter used CH30 with a maximum continuous use at 60 W. attachment method used is butt joint with a gap between the horn surface is ¼ inch zipper.Thermoplastic material in this case used nylon 66.

Effect of Heating Time Duration on Synthesis of Colloidal Silver Nanoparticles

Size-controlled silver nanoparticles are prepared at two different heating time duration (30 and 60min) under conventional heating at 80 ̊C in an aqueous solution of silver nitrate (AgNO3) as a precursor and trisodium citrate (C6H5O7Na3.2H2O) as a reducing agent under continuous stirring. The size and size distribution of the resulting silver nanoparticles prepared under conventional heating are strongly dependent on the duration of heating. As the heating duration is increased, aggregation and grain growth is observed. When duration of heating was 60min a distinct increase in the particles size was observed that lead to shift in the plasmon band as confirmed by UV-Vis absorption spectroscopy. TEM images shows that silver nanoparticles are nearly spherical in shape and their sizes are ranging between 2-42 nm and their cubic structure was confirmed by X-ray diffractogram. From X-ray diffractogram we calculated crystallite size using Scherrer’s equation which comes out to about 36nm and that determined from Hall-Williamson plot turns out to be 19nm.

Simultaneous Design Approach to Transient Electromagnetic and Thermal Problems Based on a Black-Box Modeling Concept

This paper proposes a black-box model-based design method for a transient electromagnetic (EM) and thermal (TM) problem, where EM and TM material properties are strongly coupled with each other. For a practical and efficient black-box modeling, the Kriging method is combined with a hyper-cubic local window and design sensitivity values extracted from surrogate models are exploited to obtain an optimum. Such unique design scheme facilitates controlling EM and TM performances simultaneously. In addition, it can reduce the number of design iterations during the optimization process drastically. The proposed method is tested for a strongly coupled induction heating system where the design goal is to achieve a uniform temperature distribution on the surface of a metal workpiece within a given heating time duration.

Optimization of acid digestion conditions on the extraction of fatty acids from stalagmites

Lipids in stalagmites have been shown the potential for the paleoclimate reconstruction. However, the low lipid content leads to the difficulty in gaining high resolution lipid record in stalagmites because large mass of samples are required. Previous studies have validated that the acid digestion can improve the yield of lipids, especially fatty acids (FAs) and 3-hydroxy fatty acids (3-OH-FAs). In order to obtain more content of FAs and 3-OH-FAs with limited stalagmite sample weight, we investigate here how the acid digestion conditions (HCl concentration, heating temperature and time duration) could affect the yields of FAs and 3-OH-FAs. Under different concentration of HCl, from 2.0 to 6.0 mol/L, the FAs keep the same step in content variation with 3-OHFAs, and the highest yields of both two appeared under the 3 mol/L HCl. The content of 3-OH-FAs increases positively with the heating temperature from 80°C to 150°C, while FAs showed the highest content at 130°C. Both of FAs and 3-OH-FAs firstly increased to a high content and then decreased as the heating time duration varies from 1.0 to 4.0 h, with the highest yields of both two being at 3.0 h. Consequently, we suggest the optimized acid digestion condition is under 3 mol/L HCl, heating at 130°C for 3 h and 5 g of each stalagmite sample are sufficient for the lipid analysis.

Improvement of microwave-assisted hydrolysis of cassava pulp and tapioca flour by addition of activated carbon.

The superior effects of addition of activated carbon were evidenced for microwave assisted hydrolysis of starches in cassava pulp and tapioca flour under hydrothermal conditions varying irradiation temperature (160-230°C at 5min), duration of heating time (5-18min at 210°C) and amount of activated carbon at 0.5-2.0:1:20 of activated carbon:solid:liquid ratio. The presence of 1.0g/g in microwave-assisted hydrolysis gave much improved glucose yields (44.49% for cassava pulp and 71.93% for tapioca flour) at lower heating temperature (220°C and 200°C, each for 5min) with suppressed formation of secondary decomposed compounds than those without addition of activated carbon (32.41% in cassava pulp at 230°C and 55.11% in tapioca flour at 240°C, each for 5min). The highest glucose yield from cassava pulp (52.27%) was obtained after heating at 210°C for 15min.

ASSESSMENT OF REDUCTION BEHAVIOR OF HEMATITE IRON ORE PELLETS IN COAL FINES FOR APPLICATION IN SPONGE IRONMAKING

Studies on isothermal reduction kinetics (with F grade coal) in fired pellets of hematite iron ores, procured from four different mines of Orissa, were carried out in the temperature range of 850–1000°C to provide information for the Indian sponge iron plants. The rate of reduction in all the fired iron ore pellets increased markedly with a rise of temperature up to 950°C, and thereafter it decreased at 1000°C. The rate was more intense in the first 30 minutes. All iron ores exhibited almost complete reduction in their pellets at temperatures of 900 and 950°C in < 2 hours' heating time duration, and the final product morphologies consisted of prominent cracks. The kinetic model equation 1 − (1 − α)1/3 = kt was found to fit best to the experimental data, and the values of apparent activation energy were evaluated. Reductions of D. R. Pattnaik and M. G. Mohanty iron ore pellets were characterized by higher activation energies (183 and 150 kJ mol−1), indicating carbon gasification reaction to be the rate-controlling step. The results established lower values of activation energy (83 and 84 kJ mol−1) for the reduction of G. M. OMC Ltd. and Sakaruddin iron ore pellets, proposing their overall rates to be controlled by indirect reduction reactions.

화해를 입은 실물크기 보통강도 RC 기둥의 거동

초록·키워드 목차 오류제보하기 등록된 정보가 없습니다. ABSTRACT1. 서론2. 실험3. 실험결과4. 결론참고문헌요약

Microwave Heating for the Preparation of Nanometer Gold Particles

In this paper we report a feasible method to synthesize gold nanoparticles with uniform size by microwave heating. In this work, a closed chamber of a microwave system with precise temperature control function was employed to synthesize the gold nanoparticles. Our data demonstrates that the temperature plays an important role in the synthesis of gold nanoparticles. With higher synthesis temperature, longer heating time duration and rapid gradient of temperature increase, the smaller diameter and the narrow size distribution of the gold nanoparticles were obtained. The concentrations of citrate represent the reductant in the synthesis reaction, which also influence the morphology of gold nanoparticles. The data demonstrates that gold nanoparticles with highly reproducible sizes could be synthesized by microwave heating.

Metal surface nitriding by laser induced plasma

We study a nitriding technique of metals by means of laser induced plasma. The synthesized layers are composed of a nitrogen concentration gradient over several μm depth, and are expected to be useful for tribological applications with no adhesion problem. The nitriding method is tested on the synthesis of titanium nitride which is a well-known compound, obtained at present by many deposition and diffusion techniques. In the method of interest, a laser beam is focused on a titanium target in a nitrogen atmosphere, leading to the creation of a plasma over the metal surface. In order to understand the layer formation, it is necessary to characterize the plasma as well as the surface that it has been in contact with. Progressive nitrogen incorporation in the titanium lattice and TiN synthesis are studied by characterizing samples prepared with increasing laser shot number (100–4000). The role of the laser wavelength is also inspected by comparing layers obtained with two kinds of pulsed lasers: a transversal-excited-atmospheric-pressure–CO2 laser (λ=10.6 μm) and a XeCl excimer laser (λ=308 nm). Simulations of the target temperature rise under laser irradiation are performed, which evidence differences in the initial laser/material interaction (material heated thickness, heating time duration, etc.) depending on the laser features (wavelength and pulse time duration). Results from plasma characterization also point out that the plasma composition and propagation mode depend on the laser wavelength. Correlation of these results with those obtained from layer analyses shows at first the important role played by the plasma in the nitrogen incorporation. Its presence is necessary and allows N2 dissociation and a better energy coupling with the target. Second, it appears that the nitrogen diffusion governs the nitriding process. The study of the metal nitriding efficiency, depending on the laser used, allows us to explain the differences observed in the layer features as purity, thickness, and surface morphology.

養魚飼料のタンパク質源‐ＩＶ ハマチに対する大豆油粕栄養価の加熱時間に伴う変化

In order to elucidate changes in the nutritive value of defatted soybean meal with the duration of heating time, the general and amino acid composition and trypsin inhibitor (TI) activity of several types of meal heated at 108°C for 0-40 min were determined, and the growth, feed conversion, protein digestibility, and body composition of young yellowtail Seriola quinqueradiata were also compared by feeding them with diets containing about 20% of each meal. The nutritive value of raw defatted soybean meal was extremely low: it had a high TI activity and high nitrogen solubility index, resulting in a low protein digestibility; its feeding caused weight loss in fish with inferior hematological characteristics and body composition. The nutritive value of the meal was markedly improved by heating it for 20 min, and was maximized by heating it for 30 min, but it decreased slightly after being heated for 40 min. The heating treatment hardly improved the general and amino acid composition of the soybean meal, while it caused a rapid inactivation of TI together with a marked improvement in protein digestibility, indicating that the improvement of its nutritive value by heating could be mainly attributed to an elimination of heat-labile growth inhibition factors such as TI. Also, the comparison in nutritive value between these heated soybean meals and soy protein concentrates suggests the continuing existence of heat-stable growth inhibition factors in the heated meal.

Hyperthermic therapy of deep seated tumors: Comparison of the heating efficiencies of an annular array applicator and a capacitively coupled radiofrequency system

Among 82 cases of deep seated tumors treated by hyperthermia with an annular array applicator (AA) and/or a capacitively coupled 8 mHz system (CCS) combined with radiation therapy, 13 cases were treated by both devices. The efficiencies of tumor heating were compared in terms of the time required to attain 42°C, the duration of heating time and the thermal dose as determined by a biological iso-effect formula for equivalent minutes at 42.5°C. Temperature profiles and percent of temperature levels > 42°C were better in the cases treated by the AA, but higher thermal doses were obtained with the CCS because longer treatment times were tolerated with the CCS than with the AA. Methods are necessary to prevent excess elevation of body temperature in the case of the AA, and to reduce superficial pain where the applicators contact the skin in the case of the CCS.