Behavior of thermo-mechanically treated rebar exposed to elevated temperatures

PurposeThe purpose of the paper is to mathematically model and predict the characteristics of thermo-mechanically treated (TMT) rebar when subjected to elevated temperatures.Design/methodology/approachData were collected from a few selected studies for developing the constitutive relations. Using the exposed temperature and the duration of heating as independent variables, the empirical relations were developed for determining the changes in mechanical properties of TMT rebars at elevated temperatures.FindingsRecrystallization of TMT rebar crystals took place around 500 °C, which led to a decrease in the dislocation density along with the increase of large-sized grains, resulting in the degradation of strength. Up to a temperature range of 500 °C, the normalized fracture strength was higher, while the normalized fracture strain is not so high. This indicated a failure of brittle nature.Originality/valueThis is an original work done by others as a study to theoretically predict the mechanical behavior of TMT rebars when exposed to elevated temperature.HighlightsThe TMT bars showed brittleness characteristics up to 500 °C and showed ductility characteristics after that on account of its recrystallization and extensive tempering of the outer martensitic rim around that temperature.The comparison between the super ductile (SD) TMT and the regular TMT exhibit shows that the SD-TMT bars were about 1.5 times more ductile than the normal ones.

Microfluidic chips for real-time PCR

The results of real-time PCR in single-chamber microfluidic chips made of silicon-glass materials and optically transparent polymethyl methacrylate are presented. Conditions for efficient thermal cycling in microchip devices with several reaction chambers are discussed. A simplified theoretical estimation of the duration of heating a liquid in a polymer microchip is proposed, the results of which correlate with experimental data.

Development of Standard Manufacturing Process of Joshanda

Unani System of Medicine (USM) has many safe and effective single drugs as well as compound formulations, which are commonly used in four forms solid (Hab, Qurs, Safoof, Kushta etc.); semisolid (Majoon, Laooq, Marham/Zamad etc.); liquid (Joshanda, Sharbat, Sheera, Rooh, Tila etc.) and gaseous (Bakhoor, Inkabab, Shamoom etc.). Joshanda, a preparation, in which Unani crude drugs are frequently used for treatment of common cold, catarrh, cough, associated respiratory distress and fever etc. Different Joshande are available in various Qarabadeen. In this paper a comprehensive summary has been made about various Joshande, about the drug and water ratio, yield of Joshanda and therapeutic uses of various Joshande, which is mentioned in different reference books of Unani System of Medicine. Documented evidence regarding their standard procedures of preparation/process standardization is meagre. Some important points are not specifically given, in the case of preparation of Joshandai.e quantity of heat and duration of heat. Therefore in the present study, apart from literature survey, one experimental study was also done by preparing different batches of Joshanda in different volumes (one litre, five litres and ten litres) at specific temperatures and observed the duration of heating and net volume of product left was also observed after giving suitable temperature. Keywords: Unani System of Medicine (USM), Standard Manufacturing Process (SMP), Joshanda, Decoction

Heat and water loss versus shelter: a dilemma in thermoregulatory decision making for a retreat-dwelling nocturnal gecko

ABSTRACTUnderstanding the interaction between upper voluntary thermal limit (VTmax) and water loss may aid in predicting responses of ectotherms to increasing temperatures within microhabitats. However, the temperature at which climate heating will force cool-climate nocturnal lizards to abandon daytime retreats remains poorly understood. Here, we developed a new laboratory protocol for determining VTmax in the retreat-dwelling, viviparous Woodworthia ‘Otago/Southland’ gecko, based on escape behaviour (abandonment of heated retreat). We compared the body temperature (Tb) at VTmax, and duration of heating, between two source groups with different thermal histories, and among three reproductive groups. We also examined continuous changes in Tb (via an attached biologger) and total evaporative water loss (EWL) during heating. In the field, we measured Tb and microhabitat thermal profiles to establish whether geckos reach VTmax in nature. We found that VTmax and duration of heating varied between source groups (and thus potentially with prior thermal experience), but not among reproductive groups. Moreover, geckos reached a peak temperature slightly higher than VTmax before abandoning the retreat. Total EWL increased with increasing VTmax and with the duration of heating. In the field, pregnant geckos with attached biologgers reached VTmax temperature, and temperatures of some separately monitored microhabitats exceeded VTmax in hot weather implying that some retreats must be abandoned to avoid overheating. Our results suggest that cool-climate nocturnal lizards that inhabit daytime retreats may abandon retreats more frequently if climate warming persists, implying a trade-off between retention of originally occupied shelter and ongoing water loss due to overheating.

Pengaruh Penggunaan Batu Basalt Lampung dan Batubara dalam Bahan Baku terhadap Karakteristik Klinker

Experimental study on the use of basalt stone originated from Lampung has been conducted to evaluate its potential for a partial substitute of raw material in production of cement clinker. The basalt stone contains minerals of anorthite, augite, and albite phases that are required for clinker formation. In this study, the main raw materials were 80% limestone, 10% silica sand, 9% clay and 1% iron sand. The raw material in these experiments were mixtures 90% or 80% of the main raw material and 10% or 20% of basalt stone. The effect of adding coal to raw materials was also studied to see the possibility of an increase in clinkerization temperature inside the raw material mixture, and at the same time to see the effect of coal ash on clinker composition. Clinker obtained from heating of raw materials at a temperature of 1100oC had LSF of 94.1% and 95.1% (heating time of 1 and 3 hours). If heating is carried out at 1200oC, the clinker had LSF of 97.7% and 98.0% (heating time of 2 and 3 hours, respectively). Depending on the temperature and duration of heating, the clinker mostly had SM in the range of 2.18-2.40% , and AM in the range of 0,78-1.80%. Characterization using XRD showed that the clinker consisted of larnite and gehlenite phases, and dominated by CaO.Batu basalt Lampung telah diuji potensinya sebagai pengganti sebagian bahan baku utama pembuatan klinker semen. Batu basalt tersebut memiliki mineral-mineral dalam fase anorthite, augite, dan albite yang diperlukan pada pembentukan klinker. Pada penelitian ini, bahan baku utama adalah batu kapur 80%, pasir silika 10%, tanah liat 9% dan pasir besi 1%. Campuran bahan baku klinker adalah 90% atau 80% bahan baku utama dan 10% atau 20% batu basalt. Efek penambahan batubara ke dalam bahan baku klinker juga dipelajari untuk melihat kemungkinan kenaikan temperatur klinkerisasi di dalam campuran bahan baku, dan sekaligus untuk melihat efek abu batubara terhadap komposisi klinker. Klinker hasil pemanasan bahan baku pada temperatur 1100oC memiliki LSF 94,1% dan 95,1% (lama pemanasan 1 dan 3 jam). Jika pemanasan dilakukan pada 1200oC, klinker memilik LSF 97,7% dan 98,00% (lama pemanasan 2 dan 3 jam). Tergantung pada temperatur dan lama pemanasan, klinker hasil percobaan ini umumnya memiliki SM 2,18-2,40%, dan AM antara 0,78-1,80%. Karakterisasi dengan XRD menunjukkan bahwa klinker terdiri dari fase larnite dan gehlenite, dan didominasi CaO.

Additive manufacturing of self-compacting concrete through controlled heating

Construction using concrete through additive manufacturing is gaining attention. This approach involves a layer-wise deposition of concrete. A layer of printed concrete needs to be ``strong" enough to sustain the weight of layers to be printed above. These layers may not bond well with each other, however. Self-compacting concrete (SCC) may lead to a better bonding, but it may not have sufficient strength. This paper presents a method to print SCC through controlled heating. Properties of printed concrete in fresh and hardened states are studied. Heating leads to a sharp rise in the strength of freshly-printed concrete layers, but a long duration of heating may lead to a reduction in strength of printed concrete after hardening particularly if water-to-cement ratio is small or if loads are applied parallel to the printed layers.

The impact of drying on bioactive compounds of blue honeysuckle berries (Lonicera caerulea var. edulis Turcz. ex Herder)

Drying fruit is one of the simplest ways to extend the shelf-life of fruit, especially berries. Both higher temperature and time of heating significantly change the contents of some primary and secondary metabolites in honeysuckle fruit. Differences in their contents arising from different heat treatments were determined with the aid of high-performance liquid chromatography (HPLC) coupled with mass spectrophotometry (MS). The content of sugars showed a small change with drying, while organic acid contents decreased with a longer drying time. Ascorbic acid was totally degraded, regardless of the time or heating temperature. Different phenolic groups responded differently to heat intensity and time of drying. Flavanols were more sensitive to higher temperature than to duration of heating and they decreased by more than 70% at 75 °C. In contrast, the content of hydroxycinnamic acids, increased with drying by more than 75%, regardless of the time and temperature.

The impact of climate change on the building climatology parameters used for designing the buildings and constructions in Russia

The data analysis results of long-term measurements of climatic parameters in Moscow and St. Petersburg is presented. The data on change in these parameters during the year over the past 10 years is exposed. The trends have been identified and represented for the following parameters: outdoor temperature, sunshine, snow depth, wind speed, humidity, etc. The duration of heating periods for each studied year and city is considered, as well as crossings through -2℃ during these periods. Throughout the research, the impact of climatic changes on the parameters of building climatology, which are used in designing the buildings and constructions in Russia, was determined. The obtained climate information will allow predicting the energy efficiency of operation for various engineering systems in the construction sector, as well as for the long term perspective.

Fabrication of paper microfluidic devices using a toner laser printer

We developed a method to fabricate microfluidic paper-based analytical devices (μPADs) using a toner laser printer. We addressed a potential problem of pyrolysis that resulted from long duration of heating required for the penetration of the toner.