Modelling the gas–particle partitioning and water uptake of isoprene-derived secondary organic aerosol at high and low relative humidity

This study presents a characterization of the hygroscopic growth behaviour and effects of different inorganic seed particles on the formation of secondary organic aerosols (SOAs) from the dark ozone-initiated oxidation of isoprene at low NOx conditions. We performed simulations of isoprene oxidation using a gas-phase chemical reaction mechanism based on the Master Chemical Mechanism (MCM) in combination with an equilibrium gas–particle partitioning model to predict the SOA concentration. The equilibrium model accounts for non-ideal mixing in liquid phases, including liquid–liquid phase separation (LLPS), and is based on the AIOMFAC (Aerosol Inorganic–Organic Mixtures Functional groups Activity Coefficients) model for mixture non-ideality and the EVAPORATION (Estimation of VApour Pressure of ORganics, Accounting for Temperature, Intramolecular, and Non-additivity effects) model for pure compound vapour pressures. Measurements from the Cosmics Leaving Outdoor Droplets (CLOUD) chamber experiments, conducted at the European Organization for Nuclear Research (CERN) for isoprene ozonolysis cases, were used to aid in parameterizing the SOA yields at different atmospherically relevant temperatures, relative humidity (RH), and reacted isoprene concentrations. To represent the isoprene-ozonolysis-derived SOA, a selection of organic surrogate species is introduced in the coupled modelling system. The model predicts a single, homogeneously mixed particle phase at all relative humidity levels for SOA formation in the absence of any inorganic seed particles. In the presence of aqueous sulfuric acid or ammonium bisulfate seed particles, the model predicts LLPS to occur below ∼ 80 % RH, where the particles consist of an inorganic-rich liquid phase and an organic-rich liquid phase; however, this includes significant amounts of bisulfate and water partitioned to the organic-rich phase. The measurements show an enhancement in the SOA amounts at 85 % RH, compared to 35 % RH, for both the seed-free and seeded cases. The model predictions of RH-dependent SOA yield enhancements at 85 % RH vs. 35 % RH are 1.80 for a seed-free case, 1.52 for the case with ammonium bisulfate seed, and 1.06 for the case with sulfuric acid seed. Predicted SOA yields are enhanced in the presence of an aqueous inorganic seed, regardless of the seed type (ammonium sulfate, ammonium bisulfate, or sulfuric acid) in comparison with seed-free conditions at the same RH level. We discuss the comparison of model-predicted SOA yields with a selection of other laboratory studies on isoprene SOA formation conducted at different temperatures and for a variety of reacted isoprene concentrations. Those studies were conducted at RH levels at or below 40 % with reported SOA mass yields ranging from 0.3 % up to 9.0 %, indicating considerable variations. A robust feature of our associated gas–particle partitioning calculations covering the whole RH range is the predicted enhancement of SOA yield at high RH (> 80 %) compared to low RH (dry) conditions, which is explained by the effect of particle water uptake and its impact on the equilibrium partitioning of all components.

A review on the development of electro-carburisation process

The purpose of this paper is to review the early development of electro-carburisation technology and the research findings related to the electro-carburisation process. In general, conventional liquid carburisation of steel using a molten cyanide bath is carried out to improve the performance of mild steel, however this process produces toxic cyanide waste. Thus, other alternatives for liquid carburisation are necessary. Electro-carburisation process using carbonate-base molten salt, under a CO2 environment was developed as one of the alternatives to liquid carburising. Metal to be treated is exposed to the carbon-rich liquid in the molten cyanide bath and electro-carburisation. However, the metal is simply immersed inside the cyanide bath during conventional liquid carburising, while connected to the cathode in the electro-carburisation. The electro-carburisation involves a diffusion of carbon atoms into the surface of the metal which enhance the surface hardness of the metal. The effects of electrolysis parameters to the surface hardness and case hardening of treated metal have been reported in several journals. This article summarises the research findings. Apart from that, the quenching process and heat treatment post quenching also plays an important role in the quality of the carburised metal, therefore also reviewed in this article.

DETERMINATION AND MODELING OF THE LIQUIDUS SURFACE, VAPOR PRESSURE AND IMMISCIBILITY BOUNDARIES IN THE Cu–Pb–S SYSTEM

For the first time using a membrane zero-manometer, the vapor pressure S2 over the surface of the PbS liquidus in the ternary system Cu–Pb–S were determined in the range 1100÷1400 K and 0÷760 mm Hg. Based on the thermodynamic calculation, the boundaries of the immiscibility of liquid alloys of the Cu–S, Pb–S, and Cu–Pb–S systems were determined and analytically described. Critical temperatures and pressures for immiscibility regions of sulfur-rich liquid alloys are characterized by high values: Tcr= 1520÷1880 K; Pcr=170÷510 atm. The crystallization surfaces of lead sulfide with electronic conductivity (p-type PbS) and with hole conductivity (n-type PbS) are calculated and analytically de-scribed, as well as the corresponding values of sulfur vapor pressure over the crystallization surface of lead sulfide. All analytical dependencies for 3D modeling were obtained and visualized using the OriginLab computer program

Automatic Data Acquisition and Monitoring Device to Indicate the Freshness of Milk during Transportation

Milk is a nutrient-rich liquid food and it is the primary source of nutrition and a cheap source of protein for large vegetarian population living in India. Dairy industry in India is the world's largest milk producer and dominates about 13% of world milk production. Milk contains several groups of nutrients & considerable amount of organic substances and functional elements such as traces of vitamins, enzymes & dissolved gases, dissolved salts, calcium, water, carbohydrates, proteins, fats, complex & simple lipids, minerals, vitamins , etc.,. Milk transportation has shown to contribute to a greater extent to milk spoilage. Most of the milk which has been rejected by milk processing plants had samples which indicate milk of good quality at farm level before transportation. Milk processors request that milk must be cooled to 2°C to 4°C within 2 to 3 h of milking. The monitoring system that we have implied here is to check the temperature throughout the transportation using micro-controller and to ensure the quality of the milk. This monitoring device consist of NTC Temperature sensor to indicate the exposure to excessive temperature and controlled temperature like cold storage and a gas sensor is used to detect the spoilage of milk while transportation. The RFID tags are used to record the information of the vendor, temperature and how much litre they are giving to the society and hereby, the complete record of this is maintained separately by data acquisition system with the open source software cayenne. In this monitoring device, the temperature of the milk is continuously monitored using microcontroller and an immediate alert message is given to the driver and admin when there is raise in temperature. Keywords: Milk, cayenne, data acquisition, RFID, NTC

Wetting Behavior of the Ag-5CuO Brazing Alloy on ZTA Composite Ceramic with/without CuO Coating in Air

The wetting of Ag-5 wt.% CuO (Ag-5CuO) alloy on initial/CuO-coated zirconia toughened alumina (ZTA) composite ceramic in air was studied in detail. The results showed that the contact angle of the Ag-5CuO/ZTA system rapidly decreased from 81° at 970 °C to 45° at 990 °C during the heating process, however, moderate reductions in contact angle were observed in the subsequent heating and temperature holding stages. In comparison with the contact angle of pure Al2O3, an increment of about 4° of the stable contact angle of Ag-5CuO alloy on the heterogeneous ZTA was observed. The reaction between Al2O3 and CuO can reduce the damage of the CuO-rich liquid to ZrO2 in the ZTA substrate. Both oxygen and CuO were helpful in reducing the contact angle of Ag on ZTA and enhancing the bonding of the Ag/ZTA interface. The continuous CuO coating on ZTA and the monotectic liquid containing more CuO in the region near the triple line induced reductions of more than 40° and about 10° in the contact angle, respectively, between the initial and the CuO coating-improved wetting systems.

Cocos nucifera (coconut).

C. nucifera is believed to have originated in the Indo-Malayan to Western Pacific region (Parrotta, 1993) and is now of pan-tropical distribution, mainly the result of cultivation for its nuts and by natural dispersal by the oceans. It can be cultivated up to an elevation of 1200 m near the equator or 900 m at higher latitudes (Moistero, 1978), with annual rainfall of 700-5000 mm but growth and fruit production are reduced at the extremes (Parrotta, 1993). Commercial production of coconuts is mainly concentrated in low coastal lands. It prefers deep, fertile and adequately drained soils at pH 5.5-6.5, with either a high water-table or continually replenished surface soil moisture (Francis and Liogier, 1991; PCARRD, 1993). Generally, C. nucifera is propagated from seeds (the nuts), which take 8-10 weeks to germinate and 30 weeks to reach planting-out size. It is intolerant of shade, self-pruning, highly resistant to wind damage and may tolerate some salinity (Parrotta, 1993). Besides its nuts, C. nucifera trees are of enormous general utility. The timber is used for poles, construction, furniture, boxes, fixtures, particle board, paper pulp, charcoal, and occasionally veneers. The wood is difficult to saw, requiring tungsten carbide teeth. Coconut milk may be drunk or used as a medium for tissue culture; the copra (dried endosperm) is used for extraction of oils for use in foods, cosmetics, and medicines; the cori (mesocarp fibres) is used to construct mats, ropes, carpets, brushes, brooms, and bags, packaging, and potting media; the shell is used to make bowels, cups, spoons, ladles, smoking pipes, ashtrays, vases, boxes, and toys. The leaves are used in thatching, and the terminal bud may be eaten as a vegetable. The roots have medicinal properties, and provide a sweet sucrose-rich liquid known as toddy (Westphal and Jansen, 1989).

Modelling the gas–particle partitioning and water uptake of isoprene-derived secondary organic aerosol at high and low relative humidity

This study presents a characterization of the hygroscopic growth behaviour and effects of different inorganic seed particles on the formation of secondary organic aerosols (SOA) from the dark ozone-initiated oxidation of isoprene at low NOx conditions. We performed simulations of isoprene oxidation using a gas-phase chemical reaction mechanism based on the Master Chemical Mechanism (MCM) in combination with an equilibrium gas–particle partitioning model to predict the SOA concentration. The equilibrium model accounts for non-ideal mixing in liquid phases, including liquid–liquid phase separation (LLPS), and is based on the AIOMFAC model for mixture non-ideality and the EVAPORATION model for pure compound vapour pressures. Measurements from the Cosmics Leaving Outdoor Droplets (CLOUD) chamber experiments conducted at the European Organization for Nuclear Research (CERN) for isoprene ozonolysis cases, were used to aid in parameterizing the SOA yields at different atmospherically relevant temperatures, relative humidity (RH) and reacted isoprene concentrations. To represent the isoprene ozonolysis-derived SOA, a selection of organic surrogate species is introduced in the coupled modelling system. The model predicts a single, homogeneously mixed particle phase at all relative humidity levels for SOA formation in the absence of any inorganic seed particles. In the presence of aqueous sulfuric acid or ammonium bisulfate seed particles, the model predicts LLPS to occur below ~80 % RH, where the particles consist of an inorganic-rich liquid phase and an organic-rich liquid phase; however, with significant amounts of bisulfate and water partitioned to the organic-rich phase. The measurements show an enhancement in the SOA amounts at 85 % RH compared to 35 % RH for both the seed-free and seeded cases. The model predictions of RH-dependent SOA yield enhancements at 85 % RH vs. 35 % RH are 1.80 for a seed-free case, 1.52 for the case with ammonium bisulfate seed and 1.06 for the case with sulfuric acid seed. Predicted SOA yields are enhanced in the presence of an aqueous inorganic seed, regardless of the seed type (ammonium sulfate, ammonium bisulfate or sulfuric acid) in comparison with seed-free conditions at the same RH level. We discuss the comparison of model-predicted SOA yields with a selection of other laboratory studies on isoprene SOA formation conducted at different temperatures and for a variety of reacted isoprene concentrations.