Long-time Heating Research Articles

Effect of microwave heating on rock damage and energy evolution

Rock fragmentation efficiency can be increased by microwave heating. The mechanical properties and energy evolution characteristics of coarse sandstone specimens under different microwave heating conditions are compared in this paper. The effects of microwave heating time and power on coarse sandstone specimens of peak stress, elastic modulus, brittleness index, damage variable, and impact energy index are analyzed. The results indicate that the microwave heating power and microwave heating time are inversely proportional to peak stress and elastic modulus and directly proportional to peak strain. With the increase of microwave heating power and microwave heating time, the brittleness index and damage variable of rock specimens increase, the impact energy index decreases. The microwave heating power and microwave heating time increase the rock brittleness index. The energy absorption rate of rock specimens decreases with the increase of microwave heating time. The impact energy index is inversely proportional to microwave heating power and microwave heating time. High-power and long-time microwave heating can reduce the possibility of rockbursts and the intensity of potential dynamic disasters. The research conclusion can provide the theoretical and technical basis for breaking rock by microwave heating.

Quality by design−aided acid-free synthesis of self P, N, S-doped black seed-derived carbon quantum dots for application as a nanosensor for eltrombopag environmental and bioanalysis and pharmacokinetic assay

Herein, we developed a rapid, one-step, and cost-effective methodology based on the fabrication of water-soluble self-nitrogen, sulfur, and phosphorus co-doped black seed carbon quantum dots (BSQDs) via microwaveirradiation in six minutes. Our synthesis approach is superior to those in the literature as they involved long-time heating (12 h) with sulfuric acid and sodium hydroxide and/or high temperatures (200 °C). A full factorial design was applied to obtain the most efficient synthesis conditions.BSQDs displayed excitation-independent emissions, demonstrating the purity of the synthesized BSQDs, with a maximum fluorescence at 425 nm after excitation at 310 nm. Eltrombopag olamine is an anti-thrombocytopenia drug that is also reported to cause toxicity in river water based on its Persistence, Bioaccumulation, and Toxicity (PBT). The synthesized BSQDs were employed as the first fluorometric sensor for environmental and bioanalysis of eltrombopag. The fluorescence of BSQDs decreased with increasing concentrations of eltrombopag, with excellent selectivity and sensitivity down to 30 ppb. BSQDs were successfully applied as sensing probes for the detection of eltrombopag in medical tablets, spiked and real human plasma samples, and river water samples, with an overall recovery of at least 97 %. The good tolerance to high levels of foreign components and co-administered drugs indicates good selectivity and versatility of the proposed methodology. Plasma pharmacokinetic parameters such as t1/2, Cmax, and t max of eltrombopag were evaluated to be 9.91 h, 16.0 μg mL−1, and 5 h, respectively. Moreover, the green character of the BSQDs as a sensor was proved by various analytical greenness scales.

Aminodiphosphine substituted 2Fe2Se complex as new precursor to single and double butterfly Fe/Se models related to FeFe hydrogenase models

A convenient way to synthesize the aminediphosphine (PNP) substituted Fe/Se models with [Fe2(µ-Se2)(CO)4(μ-PNP)] as a new precursor was described. Firstly, treatment of [Fe2(µ-SeR)2(CO)6] (R = C6H5 and CH2C6H5) with (Ph2P)2NBui in refluxing xylene gave [Fe2(μ-SeR)2(CO)4(μ-Ph2P)2NBui] (R = C6H51 and CH2C6H52). Further debenzylation reaction was found in complex 2 after long-time heating, and precursor complex [Fe2(μ-Se2)(CO)4(μ-Ph2P)2NBui] (3) was isolated with satisfactory yield. GC–MS analysis showed that the reaction involved the formation of (C6H5CH2)2. Further, the “open” single butterfly complex 2 and “closed” butterfly complex [Fe2(µ-pdSe)(CO)4(μ-Ph2P)2NBui] (pdSe = Se(CH2)3Se) (4) were conveniently prepared via a new synthetic route involving the reaction of 3 with 2 equiv of Et3BHLi, followed by treatment of the resulting [Fe2(μ-SeLi)2(CO)4(μ-Ph2P)2NBui] with BzBr (Bz = CH2C6H5) and Br(CH2)3Br, respectively. On the other hand, to obtain a double butterfly complex [{Fe2(μ-SeEt)(CO)4(μ-Ph2P)2NBui}2(μ-Se2)] (5), the first Fe4Se4 carbonyl model containing two PNP substituents, successive reactions were performed, including treating precursor complex 3 with EtMgBr, protonation with CF3CO2H (TFA), and air-direct oxidation. All the complexes were well characterized by various spectral techniques and particularly by X-ray crystallography. Moreover, a comparison of the electrochemical and electrocatalytic properties of single and double clusters 4 and 5 is also presented.

Failure mechanisms of the bonded interface between mold epoxy and metal substrate exposed to high temperature

The fast development of electric vehicles promoted the development of next-generation power modules. Along with this trend, the encapsulation techniques are also transforming from previous gel encapsulation to epoxy encapsulation because epoxy encapsulation reduces the module size significantly. However, the dissimilar bonding between the epoxy and the metal substrate is a weak part of the entire module. Unlike previous studies, which focused on epoxy properties and thermal stress, we investigated the failure mechanisms between the encapsulation epoxy and the copper substrate under high temperatures by considering the interfacial interaction. A high-temperature storage test (HST) was performed at 200 °C until 1000 h for encapsulated packages. We then measured the bonding strength and identified the fracture path at the nanoscale by SEM, XPS, and ToF-SIMS depth profiling. In addition, the changes in the epoxy were characterized by ATR-FTIR, nanoindentation, and XPS depth profiling. The bonding interface was analyzed with AFM-IR, SEM, EDS, and STEM. We found that the fracture happened inside the epoxy rather than the copper/epoxy interface. More importantly, we found that copper atoms diffused into the epoxy reaching approximately 100 nm. The diffused copper atoms and the long-time high-temperature heating promoted the epoxy pyrolysis, forming a 100 nm thick weak layer at the epoxy side, which is the key reason for the high-temperature failure. Our study provided a fresh understanding of the failure mechanisms of the bonding between encapsulation epoxy and the copper substrate under HST, which will contribute significantly to future power module design and material development.

Experimental synthesis of Fe-bearing olivine at near-solidus temperatures and its decomposition during longtime heating

Experimental synthesis of Fe-bearing olivine at near-solidus temperatures and its decomposition during longtime heating

Cenosphere-Based Zeolite Precursors of Lutetium Encapsulated Aluminosilicate Microspheres for Application in Brachytherapy.

Coal fly ash hollow aluminosilicate microspheres (cenospheres) of stabilized composition (glass phase—95.4; (SiO2/Al2O3)glass—3.1; (Si/Al)at. = 2.6) were used to fabricate lutetium-176 encapsulated aluminosilicate microspheres as precursors of radiolabeled microspheres applied for selective irradiation of tumors. To incorporate Lu3+ ions into cenosphere’s aluminosilicate material, the following strategy was realized: (i) chemical modification of cenosphere globules by conversion of aluminosilicate glass into zeolites preserving a spherical form of cenospheres; (ii) loading of zeolitized microspheres with Lu3+ by means of ion exchange 3Na+ ↔ Lu3+; (iii) Lu3+ encapsulation in an aluminosilicate matrix by solid-phase transformation of the Lu3+ loaded microspheres under thermal treatment at 1273–1473 K. Two types of zeolitized products, such as NaX (FAU) and NaP1 (GIS) bearing microspheres having the specific surface area of 204 and 33 m2/g, accordingly, were prepared and their Lu3+ sorption abilities were studied. As revealed, the Lu3+ sorption capacities of the zeolitized products are about 130 and 70 mg/g Lu3+ for NaX and NaP1 microspheres, respectively. It was found that the long-time heating of the Lu3+-loaded zeolite precursors at 1273 K in a fixed bed resulted in the crystallization of monoclinic Lu2Si2O7 in both zeolite systems, which is a major component of crystalline constituents of the calcined microspheres. The fast heating–cooling cycle at 1473 K in a moving bed resulted in the amorphization of zeolite components in both precursors and softening glass crystalline matter of the NaX-bearing precursor with preserving its spherical form and partial elimination of surface open pores. The NaX-bearing microspheres, compared to NaP1-based precursor, are characterized by uneven Lu distribution over the zeolite-derived layer. The precursor based on gismondin-type zeolite provides a near-uniform Lu distribution and acceptable Lu content (up to 15 mol.% Lu2O3) in the solid phase.

Fabrication of superhydrophobic and flame-retardant polyethylene terephthalate fabric through a fluorine-free layer-by-layer technique

Abstract Polyethylene terephthalate (PET) fabric materials are broadly applied in daily life. However, on one hand, they suffer problem of easy contamination by dust owing to their hydrophilicity, which largely reduce their lifetime. On the other hand, their inflammability will bring many potential safety hazards. Therefore, in this paper, PET fabric material with superior superhydrophobicity and flame retardance through a fluorine-free layer-by-layer (LBL) method was developed, which effectively extended its lifetime and range of applications. The LBL technique was realized through assembly of the mixed polyelectrolytes include chitosan (CS), phytic acid (PA), and ammonium polyphosphate (APP) for only two bilayers (BL), which endowed the fabric superior fire retardance. A final layer consisted of steel slag (SS) particles and octadecylamine (ODA) were further assembled onto the flame-retardant fabric, which successfully gave rise to superior superhydrophobicity with water contact angle (WCA) of 155° and water sliding angle (WSA) of 2°. Compared with the pure fabric, the limited oxygen index (LOI) values of the coated fabric were enhanced from 19.8% to 29.2%. The finally obtained fabric also showed excellent self-cleaning and anti-fouling capabilities. It could be used to highly efficiently separate various oil–water mixtures. It also could endure long-time heating treatment at high temperature of 180 °C without affecting the superhydrophobicity and flame retardance. This method was fluorine-free and made good use of waste SS particles. Such fabric was believed to find vary promising applications in water repellence, self-cleaning, flame retardance, anti-fouling, and liquid separation fields.

Effect of diamond microparticles on the thermal behavior of low melting point metal: An experimental and numerical study

Low melting point metal (LMPM) based composite containing particles with high thermal conductivity has potential application prospects in the field of thermal management. To investigate the influence of particles with high thermal conductivity on the thermal behavior of LMPM during its melting/solidification process, lead free eutectic field's metal Bi32.5In51Sn16.5 was selected as the LMPM and diamond microparticles were used as the thermal conductive reinforcement. The thermal conductivity of the LMPM increased 85% as the mass fraction of diamond particles was 4.7%. Thermal performance of LMPM-based heat sink influenced by diamond particles was studied. Compared with the LMPM-based heat sink, heating element using heat sink filled with LMPM/diamond composites maintained a lower temperature during long-time heating and cooled faster as its power-off. The effect of diamond particles on the melting/solidification process of LMPM was investigated. The melting duration of LMPM was prolonged by adding diamond particles. After LMPM was compounded with diamond, the subcooling existing in LMPM was reduced and its initial solidification time was shortened. The thermal performance of LMPM/diamond-based heat sink showed more stability than that of LMPM-based heat sink during the heating/cooling cyclic tests. Meantime, the relative position of diamond particles in LMPM was basically immobile through 1000 melting/solidification cyclic tests.

Desorption of nutrients and flavor compounds formation during the cooking of bone soup

In order to identify the effects of varying cooking time on the quality of bone soup, the diversification of nutrient profiles and flavor compounds in bone soup prepared within 10 h' cooking was studied. The Kjeldahl method, inductively coupled plasma mass spectrometry (ICP-MS), automatic amino acid analyzer (AAA analyzer), high performance liquid chromatography (HPLC), solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) were applied to determine the changes o f crude protein, minerals, free amino acids (FAAs), 5′-nucleotides, and volatile compounds in the soup, respectively. During the 10 h cooking, the concentration of nutrients and flavor compounds reached their maximum and then decreased, except for minerals, which continued to increase in concentration. 18 FAAs were identified in all samples, which were related with I-collagen hydrolysis. Taste FAAs contributed little to the flavor of soup. Bitter amino acids increased significantly (P < 0.05) and IMP + GMP reached maximum concentration at the seventh hour of cooking. The main flavor compounds of bone soup were aldehydes, which increased significantly (P < 0.05) during boiling. Samples taken at the fourth and fifth hours contained the richest profile of volatile flavor compounds. In general, for high-quality bone soup, cooking time should be limited to achieve an appropriate balance between nutrient dissolution and flavor formation. • Crude protein and FAAs had dissolution equilibrium within atmospheric cooking. • Minerals increased with the extension of cooking time. • IMP + GMP may enhance the aroma of soup to the utmost extent at 7th hour. • Long-time heating destroyed the diversity of flavor and taste compounds and led to the loss of volatile flavor compounds. • Content of nutrients and flavor compounds was low in pure bone soup.

Effects of different heating conditions on protein composition in each muscle type of yellowtail (Seriola quinqueradiata)

To clarify the factors influencing the physical properties of fish after heat treatments, we investigated changes in the properties of proteins in the dorsal ordinary and dark muscle of yellowtail (Seriola quinqueradiata) heated under different conditions commonly used for the purposes of food hygiene. High-temperature/short-time heating (85°C for 90 s and 75°C for 60 s) affected the protein solubility more than low-temperature/long-time heating (63°C for 30 min). Sodium dodecyl sulphate-polyacrylamide gel electrophoresis and differential scanning calorimetry showed that low-temperature/long-time heating reduced the degree of actin denaturation in fish compared with that by other heating conditions. In addition, collagen solubility was enhanced with low-temperature/long-time heating. Therefore, these results suggest that differences in the degree of actin and collagen denaturation are responsible for the enhanced meat tenderness and diminished meat shrinkage, resulting from low-temperature/ long-time heating.

Effect of Heat Treatment on Oxidation of Hazelnut Oil.

Thermal processing, a common processing method of vegetable oil in daily life, is accompanied by the formation of some harmful substances. This study determined the peroxide value, anisidine value, total peroxide value, polar compound content, fatty acid content, and core aldehyde content of hazelnut oil under different thermal processing conditions. The oxidation kinetics equation of fatty acid and temperature of hazelnut oil was established, and the correlation between the contents of fatty acid and core aldehyde and four oxidation indexes was analyzed. The results showed that the TPC of hazelnut oil exceeds 24% when heated for 10 min at 210ºC, indicating that hazelnut oil is not suitable for high temperature and long-time heating. The contents of linoleic acid and oleic acid in hazelnut oil varied significantly at different thermal processing temperatures (p ≤ 0.01). The change of linoleic acid was more consistent with the first-order oxidation kinetics model. Two core aldehydes were detected in hazelnut oil, aldehyde 9-oxo and aldehyde 10- oxo-8. The core aldehyde 9-oxo content changed most obviously with the heating temperature, and it was the main non-volatile aldehydes of hazelnut oil thermal oxidation. Correlation analysis showed that the heating temperature of hazelnut oil had a significant effect on the oxidation index (p ≤ 0.01), and linoleic acid had the strongest correlation with the oxidation index, which could reflect the overall oxidation of hazelnut oil. The total amount of core aldehyde and the content of core aldehyde 9-oxo strongly correlated with the oxidation index (p ≤ 0.01), which can be used as one of the indicators to evaluate the oxidation degree of hazelnut oil. This study is of great significance for promoting the application of hazelnut oil in daily cooking and processing.

Floquet Prethermalization with Lifetime Exceeding 90s in a Bulk Hyperpolarized Solid.

We report the observation of long-lived Floquet prethermal states in a bulk solid composed of dipolar-coupled ^{13}C nuclei in diamond at room temperature. For precessing nuclear spins prepared in an initial transverse state, we demonstrate pulsed spin-lock Floquet control that prevents their decay over multiple-minute-long periods. We observe Floquet prethermal lifetimes T_{2}^{'}≈90.9 s, extended >60 000-fold over the nuclear free induction decay times. The spins themselves are continuously interrogated for ∼10 min, corresponding to the application of ≈5.8×10^{6} control pulses. The ^{13}C nuclei are optically hyperpolarized by lattice nitrogen vacancy centers; the combination of hyperpolarization and continuous spin readout yields significant signal-to-noise ratio in the measurements. This allows probing the Floquet thermalization dynamics with unprecedented clarity. We identify four characteristic regimes of the thermalization process, discerning short-time transient processes leading to the prethermal plateau and long-time system heating toward infinite temperature. This Letter points to new opportunities possible via Floquet control in networks of dilute, randomly distributed, low-sensitivity nuclei. In particular, the combination of minutes-long prethermal lifetimes and continuous spin interrogation opens avenues for quantum sensors constructed from hyperpolarized Floquet prethermal nuclei.

Towards laser printing of magnetocaloric structures by inducing a\xa0magnetic phase transition in iron-rhodium nanoparticles

The development of magnetocaloric materials represents an approach to enable efficient and environmentally friendly refrigeration. It is envisioned as a key technology to reduce CO2 emissions of air conditioning and cooling systems. Fe-Rh has been shown to be one of the best-suited materials in terms of heat exchange per material volume. However, the Fe-Rh magnetocaloric response depends on its composition. Hence, the adaptation of material processing routes that preserve the Fe-Rh magnetocaloric response in the generated structures is a fundamental step towards the industrial development of this cooling technology. To address this challenge, the temperature-dependent properties of laser synthesized Fe-Rh nanoparticles and the laser printing of Fe-Rh nanoparticle inks are studied to generate 2D magnetocaloric structures that are potentially interesting for applications such as waste heat management of compact electrical appliances or thermal diodes, switches, and printable magnetocaloric media. The magnetization and temperature dependence of the ink’s γ-FeRh to B2-FeRh magnetic transition is analyzed throughout the complete process, finding a linear increase of the magnetization M (0.8 T, 300 K) up to 96 Am2/kg with ca. 90% of the γ-FeRh being transformed permanently into the B2-phase. In 2D structures, magnetization values of M (0.8 T, 300 K) ≈ 11 Am2/kg could be reached by laser sintering, yielding partial conversion to the B2-phase equivalent to long-time heating temperature of app. 600 K, via this treatment. Thus, the proposed procedure constitutes a robust route to achieve the generation of magnetocaloric structures.

Facile preparation of wearable heater based on conductive silver paste with low actuation voltage and rapid response

Towards emerging electric heaters for wearable electronics, actuators and high-performance heating systems, various properties including flexibility, low actuation voltage, rapid response, facile adaptability, thermal and mechanical stability are highly desired. Herein, a high-performance heater based on commercial conductive silver paste is proposed, through quite simple scrape coating, painting and pen writing. Benefiting from its excellent viscosity, the silver paste can be firmly coated on a variety of substrates, even including hydrophobic and oleophobic polytetrafluoroethylene and cotton thread of high curvature. After curing the silver paste, the silver nanoflakes inside are encapsulated in a polymer framework and are closely interconnected, forming a reliable conductive network with low sheet resistance ( $${\text{minimum }}0.{18 }\Omega /{\text{sq}}$$ ). This structure protects the silver nanoflakes from oxidation and provides this flexible silver heater (FSH) excellent thermal and mechanical stabilities, as demonstrated by long-time heating, cyclic heating and multiple deformation tests. The FSH achieves high surface temperature (280 °C) at a low operation voltage (2 V), with rapid thermal response time (less than 7 s). The application demonstrations of FSHs in custom-shaped wearable heaters and heating patterns, thermal therapy, flexible heating thread and thermal switch suggest the distinct advantages of FSHs in flexible and wearable devices.

Visible-light-assisted multimechanism design for one-step engineering tough hydrogels in seconds

Tough hydrogels that are capable of efficient mechanical energy dissipation and withstanding large strains have potential applications in diverse areas. However, most reported fabrication strategies are performed in multiple steps with long-time UV irradiation or heating at high temperatures, limiting their biological and industrial applications. Hydrogels formed with a single pair of mechanisms are unstable in harsh conditions. Here we report a one-step, biocompatible, straightforward and general strategy to prepare tough soft hydrogels in a few tens of seconds under mild conditions. With a multimechanism design, the network structures remarkably improve the mechanical properties of hydrogels and maintain their high toughness in various environments. The broad compatibility of the proposed method with a spectrum of printing technologies makes it suitable for potential applications requiring high-resolution patterns/structures. This strategy opens horizons to inspire the design and application of high-performance hydrogels in fields of material chemistry, tissue engineering, and flexible electronics.

Influence of Lithium Mass Transfer on Tritium Behavior in Pebbles of Li2TiO3 with Excess Lithium

• Li 2 TiO 3 with excess Li was heated at 900 °C for 30 days in 1000 Pa H 2 /Ar flow. • Li mass loss was 0.7 wt%, grain size increased and BET surface area decreased. • The majority of evaporative Li was lost by first 3 days. • The influence of the 30 days heating on tritium behavior was not large. • Tritium recovery by isotope exchange with H 2 was effective at 600 °C and 900 °C. Tritium breeding ceramic materials are placed at high temperatures for a long period in a fusion DEMO reactor. Therefore, the understanding of Li mass loss phenomena and its influence on tritium behavior are important. In this study, the pebbles of Li 2 TiO 3 with excess Li were heated at 900 °C for 30 days in a 1000 Pa H 2 /Ar flow and tritium sorption and recovery experiments were carried out. Li mass loss by the heating was evaluated to be 0.7 wt%. The value of Li mass loss was almost same as that for 3 days heating at the same condition. Tritium sorption capacity for the heated pebbles at 600 °C and 900 °C were almost same as that for the pebbles as received. Tritium sorbed in the pebbles could not be recovered effectively by the 1000 Pa H 2 /Ar purge at room temperature and 300 °C but it could be recovered at 600 °C and 900 °C. The influence of the long-time heating on the behavior of tritium sorbed in the pebbles was not large.

Enhanced formability and forming efficiency for two-phase titanium alloys by Fast light Alloys Stamping Technology (FAST)

During hot stamping of titanium alloys, insufficient forming temperatures result in limited material formability, whereas temperatures approaching the β phase transus also result in reduced formability due to phase transformation, grain coarsening and oxidation during the long-time heating. To solve this problem, Fast light Alloys Stamping Technology (FAST) is proposed in this paper, where fast heating is employed. Effects of heating parameters on the formability and post-form strength were studied by tensile tests. Forming of a wing stiffener was performed to validate this new process. Results show that microstructure of TC4 alloy after fast heating was in nonequilibrium state, which could enhance ductility significantly compared with the equilibrium state. When TC4 alloy was first heated to 950 °C with heating rate of 100 °C/s and then cooled to 700 °C, the elongation at 700 °C was more than 3 times that of a slow heating rate with soaking. Nano-scaled martensite with high dislocation density transformed from β phase was observed under fast heating condition. A complex shaped wing stiffener was successfully formed from TC4 titanium alloy in less than 70 s including heating, transfer and forming, and the post-form strength was almost the same with the initial blank.

Low-temperature and long-time heating regimes on non-volatile compound and taste traits of beef assessed by the electronic tongue system

The influence of temperature–time combinations on non-volatile compound and taste traits of beef semitendinosus muscles tested by the electronic tongue was studied. Single-stage sous-vide at 60 and 70 °C (6 and 12 h), and two-stage sous-vide that sequentially cooked at 45 °C (3 h) and 60 °C (either 3 or 9 h) were compared with traditional cooking at 70 °C (30 min). Umami was better explained in the given model of partial least squares regression than astringency, sourness, saltiness, bitterness, and richness. Sous-vide at 70 °C for 12 h characterized the most umami, likely adenosine-5′-monophosphate (AMP) and guanosine-5′-monophosphate (GMP) as significant contributors. Two-stage sous-vide projected higher histidine, leucine, inosine, and hypoxanthine with the astringent and sour taste significant after 6 and 12 h cooking, respectively. Equivalent umami concentration (EUC) between umami amino acids and umami nucleotides showed a strong relationship to umami taste assessed by the electronic tongue.

Novel porous oil-water separation material with super-hydrophobicity and super-oleophilicity prepared from beeswax, lignin, and cotton

The traditional fluorinated porous material with super-hydrophobicity and super-oleophilicity is an effective strategy for oil-water separation. However, in recent years, fluorinated materials have been classified as “Emerging Environmental Pollutants” by U. S. Environmental Protection Agency because of difficult degradation and bio-accumulation. It is unacceptable to introduce new pollutants while solving environmental disasters. Therefore, it is great requirement to explore a low-cost, environmentally friendly, and renewable technique for the fabrication of novel porous materials with super-hydrophobicity and super-oleophilicity to separate oil-water mixtures. In this work, renewable beeswax, lignin, and cotton have been chosen to prepare the biomass-based porous materials with super-hydrophobicity and super-oleophilicity for oil-water separation. The mixture of beeswax and lignin is modified on the surface of cotton to obtain the biomass-based porous materials with super-hydrophobicity and super-oleophilicity. The beeswax and lignin provide low surface energy and micro/nanoscale structures, respectively. The introduction of lignin effectively improves the thermal stability of the porous materials. The apparent contact angle still remains to be above 150° after a long-time heating. The porous materials effectively separate oil-water mixtures and have good absorption effect for heavy oil (density greater than water). Moreover, the porous materials are easily recyclable after reactivation. This strategy of preparing oil-water separation materials from renewable natural polymers not only helps to clean the environment, but also helps to recover valuable oil.

Monitoring of Edible Oils Quality in Restaurants and Fast Food Centers Using Peroxide and Acid Values

Continuous surveillance and monitoring of used materials in food processing is a tool for achieving to food safety assurance. Peroxide and Acid values are common indicators to detect fat oxidation, frequent and longtime heating and usage of edible oils in cooking or frying of food. This study aimed to quality assessment of used edible oils in restaurants and fast food centers (Sandwich centers) of Zanjan, Iran by determination peroxide value (PV) and acid value (AV). A total 60 oil samples were collected randomly from restaurants (27 samples) and fast food centers (33 samples) based on cluster sampling plan of the Zanjan city. Titration methods were used to determine Peroxide and Acid values according to Iran national standards protocols No. 4179 and 4178. Peroxide value in 22 (81.48%) and 24 (80%) of oil samples and Acid value in 22 (81.48%) and 30 (90.9%) of samples taken from restaurants and fast food centers were higher than standard limit, respectively. Present investigation has shown that High PV and AV in used edible oils of many restaurants and fast food centers in Zanjan, Iran. High range of Peroxide and Acid values indicate an improper use of oils in food preparing centers and presence toxic compounds in used oils and foodstuffs which threaten food consumers' health. Therefore, continuous surveillance and monitoring of restaurants and food preparing centers and training of chefs, food operators in order to apply proper methods of cooking and frying food is very important and necessary.