Laboratory Oven Research Articles

Production of Pectin-Cellulose Biofilms: A New Approach for Citrus Waste Recycling

While citrus waste is abundantly generated, the disposal methods used today remain unsatisfactory: they can be deleterious for ruminants, can cause soil salinity, or are not economically feasible; yet citrus waste consists of various valuable polymers. This paper introduces a novel environmentally safe approach that utilizes citrus waste polymers as a biobased and biodegradable film, for example, for food packaging. Orange waste has been investigated for biofilm production, using the gelling ability of pectin and the strength of cellulosic fibres. A casting method was used to form a film from the previously washed, dried, and milled orange waste. Two film-drying methods, a laboratory oven and an incubator shaker, were compared. FE-SEM images confirmed a smoother film morphology when the incubator shaker was used for drying. The tensile strength of the films was 31.67 ± 4.21 and 34.76 ± 2.64 MPa, respectively, for the oven-dried and incubator-dried films, which is within the range of different commodity plastics. Additionally, biodegradability of the films was confirmed under anaerobic conditions. Films showed an opaque appearance with yellowish colour.

Level of Polycyclic Aromatic Hydrocarbon (Pahs) and Phenols in Meat Products Due to Processing Methods

ObjectivesHealth challenges may arise from eating meat products not properly processed. High temperature during smoking of meat products usually above 400°C, could result in production of Polycyclic Aromatic Hydrocarbon (PAHs) and Phenols. (PAHs) which could exhibit cancerous substance affecting human health while Phenols produced could contribute to meat flavor, aroma, taste and overall acceptability.Materials and MethodsTen kg of raw semimembranosus muscles of 2 yr old male White Fulani cattle was used and was differently cut into 2 kg each to produce Nigeria locally consumed meat products namely, Kundi, Kilishi, Balangu, Suya and Asun. Kundi products; meat was cut into 50- 80 g, oven-dried for 3 h at 170°C and smoked for 2 h at 220- 250°C. Kilishi products; meat was cut into 20cm by 25cm of 100 to 150 g, oven-dried for 5 h at 170°C and smoked dried for 2 h at 220- 250°C. Suya products; meat was cut 20 by 25cm of 100– 150 g, oven-dried for 1 h at 170°C and smoked dried for 30 min at 220– 250°C Asun products; meat was sliced into 10cm by 12cm of 40- 50 g, oven-dried 45 min at 170°C and smoke dried for 30 min at 220- 250°C. Balangu products; meat was sized into 10- 12cm of 40 –50 g, oven-dried for 45 min at 170°C and smoke dried for 30 min at 220- 250°C. Final samples were evaluated and compared with the commercial product for PAHs, phenols, proximate composition and palatability status using a completely randomized design in a factorial experiment.ResultsKundi from LTSM and CM, and Kilishi from CM had the highest PAHs level (8.00µkg–1, 8.80µkg–1, and 8.60µkg–1) respectively, while the least (P < 0.05) values (2.10µkg–1) were observed in Asun products produced using all processing methods. Kilishi from CM had the highest phenols level of (1.30µg), and least value (0.10µg) was noticed in Asun products using all processing methods. Kundi products had the highest significantly (P < 0.05) values in protein and ash content in all the processing methods. Balangu products had the highest (P < 0.05) ether extract content, while moisture content was highest in Asun products. The panelists rated Balangu, Asun and Kilishi products highest (P < 0.05) than Kundi and Suya products.ConclusionWith higher temperature and duration of time used in smoking animal products, the higher the accumulation the nutrients composition, Phenols compound and the PAHs content (which could affect human health, when consumed).Table 1The level of Polycyclic Aromatic Hydrocarbon (PAHs) status in Nigeria meat products. (µkg-1)Method1KundiKilishiBalanguSuyaAsunSEMLTM8.00a6.40b2.50f3.20e2.10f0.001LOM3.30e5.30c2.10f2.20f2.10f0.001CM8.80a8.60a4.80d3.80e2.10f0.001a-fMeans of different alphabet in both the column and row are significantly different (p < 0.05).1LTM– Laboratory traditional smoking method; LOM- Laboratory oven dried method; CM- Commercial methods.

Effect of wetting time in the sorption and in the thermal conductivity of the most commonly used structural materials

During the thermal assessment of buildings, proper understanding and knowledge of the thermal behavior of the materials is required. Certain indoor and outdoor conditions can cause moisture transfer and could change the thermal properties of buildings (e.g. thermal conductivity, resistance, thermal diffusivity, specific heat capacity, etc.). In this technical note, a research report can be found on the measured thermal conductivity after drying and wetting the samples. For the measurements, we used a dry-heat laboratory oven (Venticell 111) apparatus to dry the samples and a climatic chamber (Climacell 111) to wet the materials in order to get the values. By applying these two chambers, we were able to reach the moisture content of different humidity levels and create the kinetic wetting curves for each sample. To measure the thermal conductivity, a heat flow meter type Holometrix 2000 was used. During the measurements, five different types of materials were used (solid brick, lightweight and foam concrete, plasterboard, corkboard). In order to reach acceptable accuracy, three measurement series were carried out on the samples at each wetting times. During one series, the thermal conductivity was measured 10 times, and the average of the 13 thermal conductivity results gave the final value. Moreover, from the measurement results, new equations and functions were created to show the relationship between the thermal conductivity and the moisture content of the materials. Our results showed that after wetting the samples in a climatic chamber at 293 K and at 90% relative humidity, the kinetic function (time dependence) of adsorbed water increased in the cases of all the materials used; however, thermal conductivity only increased considerably in the cases of the two different types of concrete and of the plasterboard. Practical application: The role of insulation materials in the building energy and moisture balance is more significant compared to the other materials of the building structures. The high moisture load will require the change of the thermal parameters of the materials. Moisture is a common cause of building degradation. In fact, much of what we know about applied building science today originates from early work investigating moisture impact on buildings, while the severity of moisture problems varies greatly depending on climate. These estimations based on the laboratory measurements of these values of the insulating materials are very important either for the manufacturers or the contractors, planners, and designers.

High adhesion strength and hybrid irreversible/reversible full-PDMS microfluidic chips

To the best of our knowledge, this paper outlines for the first time high adhesion and hybrid irreversible/reversible microfluidic devices fully composed of polydimethylsiloxane (PDMS). These chips were fabricated by the sandwich bonding (SWB), a method that was recently deployed by our group. SWB offers simple, fast, and low cost operation requiring only a laboratory oven. The devices showed burst pressures of up to 4.5 MPa. This value is more than tenfold the pressures withstood by the full-PDMS chips described in literature. In terms of the reversible behavior, the ability for disassembling the chip slides is crucial in research and development stages, especially when the device integrates high-cost components or harsh cleaning steps are needed. Following successive steps of detachment and bonding, the channels still withstood high pressures of approximately 1.8 MPa. Finally, the emulsification of corn oil 4.0% w/w to polyglycerol polyricinoleate with 10.0 μmol L−1 rhodamine B aqueous solution was realized to show the relevance in enhancing the flow rate in microfluidics. Such experiment was conducted at total flow rates of 0.8–160.0 μL min−1. The decrease in size and polydispersity of the droplets was observed at increasing flow rates. Monodisperse emulsions were achieved only at 160.0 μL min−1.

Turbulence in microfluidics: Cleanroom-free, fast, solventless, and bondless fabrication and application in high throughput liquid-liquid extraction

This paper addresses an important breakthrough in the deployment of ultra-high adhesion strength microfluidic technologies to provide turbulence at harsh flow rate conditions. This paper is only, to our knowledge, the second reporting on the generation of high flow rate-assisted turbulence in microchannels. This flow solves a crucial bottleneck in microfluidics: the generation of high throughput homogeneous mixings. We focused on the fabrication of bulky polydimethylsiloxane (PDMS) microchips (without any interfaces) rather than the laborious surface modifications that were employed in the first reporting about turbulence-assisted microfluidics. The fabrication is cleanroom-free, simple, low-cost, fast, solventless, and bondless requiring only a laboratory oven. More specifically, our method relies on the shaping of a nylon scaffold, cure of PDMS with embedded nylon, and removal of this scaffold. The scaffold was obtained by manually wrapping nylon threads. The withdrawing out of the scaffold was completed in few seconds using only a plier. Such microchannels endured flow rates of up to 60.0 mL min−1 with a strikingly low elastic deformation. The importance in producing turbulence into microscale channels was successfully shown in liquid-liquid extractions. The great energy dissipation rate relative to the turbulence created high throughput and efficient extractions in microfluidics for the first time. The residence time was only 0.01 s at 25.0 mL min−1 (total flow rate of the immiscible phases). In addition, the partition coefficient determined in a single run was similar to that obtained by the conventional batch shake-flask method that was realized in triplicate.

Dehydration of the red chilli (Capsicum annuum L., costeño) using an indirect-type forced convection solar dryer

Chilli is a vegetable that is produced and consumed in various parts of the world, not only for its culinary qualities but also for its nutritional content and potential industrialization. Mexico has the highest genetic diversity of chilli, with more than 40 varieties. A dried chilli has different properties of flavour, colour and pungency and a high added value; however, information about its dehydration is scarce.In this work, the dehydration of a red chilli, the “costeño” (Capsicum annuum L.), which is highly appreciated for its organoleptic properties and used in the food industry, was carried out. The experimental study was performed at the Instituto of Energías Renovables (IER) of the Universidad Nacional Autónoma de México (UNAM) in Temixco, Morelos, México, located at 18°51′NL and 99°14′WL. The drying process was carried out at controlled temperatures of 45°C, 55°C and 65°C, using a laboratory oven and an indirect tunnel-type solar dryer. The drying kinetics between 55°C and 65°C are similar, with drying times of 2.75h and 3.0h, respectively, while at 45°C, the drying time was 6.25h. Wang and Sing’s model gave a better fit for the drying kinetics at 45°C, and the Page model was better for 55°C and 65°C.In the solar drying processes, two ranges of air velocity were established; high velocity was between 1.4 and 2.6m/s, and low velocity was between 0.7 and 1.48m/s. In both cases, a temperature between 31°C and 45°C was obtained. For the first range, the total drying time was 16h, reaching a final moisture content between 0.057kg of water/kg dry matter and 0.90kg water/kg dry matter. For the second range, the time was 21h, with a moisture content of 0.0611kg of water/kg dry matter and 0.109kg of water/kg dry matter.

Understanding microwave vessel contamination by chloride species

Microwaves are widely used to assist digestion, general sample treatment and synthesis. The use of aqua regia is extensively adopted for the closed vessel mineralization of samples prior to trace element detection, leading to the contamination of microwave vessels by chlorine containing species. The latter are entrapped in the polymeric matrix of the vessels, leading to memory effects that are difficult to remove, among which the risk of silver incomplete recoveries by removal of the sparingly soluble chloride is the predominant one. In the present paper, we determined by mass spectrometry that hydrogen chloride is the species entrapped in the polymeric matrix and responsible for vessel contamination. Moreover, several decontamination treatments were considered to assess their efficiency, demonstrating that several cleaning cycles with water, nitric acid or silver nitrate in nitric acid were inefficient in removing chloride contamination (contamination reduction around 90%). Better results (≈95% decrease) were achieved by a single decontamination step in alkaline environment (sodium hydroxide or ammonia). Finally, a thermal treatment in a common laboratory oven (i.e. without vacuum and ventilation) was tested: a one hour heating at 150°C leads to a 98.5% decontamination, a figure higher than the ones obtained by wet treatments which requires comparable time. The latter treatment is a major advancement with respect to existing treatments as it avoids the need of a vacuum oven for at least 17h as presently proposed in the literature.

Self-regenerating and hybrid irreversible/reversible PDMS microfluidic devices.

This paper outlines a straightforward, fast, and low-cost method to fabricate polydimethylsiloxane (PDMS) chips. Termed sandwich bonding (SWB), this method requires only a laboratory oven. Initially, SWB relies on the reversible bonding of a coverslip over PDMS channels. The coverslip is smaller than the substrate, leaving a border around the substrate exposed. Subsequently, a liquid composed of PDMS monomers and a curing agent is poured onto the structure. Finally, the cover is cured. We focused on PDMS/glass chips because of their key advantages in microfluidics. Despite its simplicity, this method created high-performance microfluidic channels. Such structures featured self-regeneration after leakages and hybrid irreversible/reversible behavior. The reversible nature was achieved by removing the cover of PDMS with acetone. Thus, the PDMS substrate and glass coverslip could be detached for reuse. These abilities are essential in the stages of research and development. Additionally, SWB avoids the use of surface oxidation, half-cured PDMS as an adhesive, and surface chemical modification. As a consequence, SWB allows surface modifications before the bonding, a long time for alignment, the enclosure of sub-micron channels, and the prototyping of hybrid devices. Here, the technique was successfully applied to bond PDMS to Au and Al.

Immunoassay of β2-microglobulin at oxide-coated heavily doped p-silicon electrodes

An immunoassay was carried out on disposable oxide-coated silicon chip electrodes made of heavily doped p-type silicon, simply thermally oxidized in room air in a laboratory oven. The present electrode chips allow injection of hot electrons into aqueous electrolyte solutions and can be utilized in detecting electrochemiluminescent labels in fully aqueous solutions. This is demonstrated with an immunoassay of β2-microglobulin using an aromatic Tb(III) chelate as an electrochemiluminescent label.

Evaluation of the Influence of Specific Surface Treatments of RBA on a Set of Properties of Concrete.

High water absorption of recycled brick aggregate (RBA) is one of the most discussed parameters in terms of its application in the production of concrete—its influence on the amount of mixing water and, hence, the quality of the concrete, is usually considered negative. In this paper, different methods of decreasing the absorption of RBA and, consequently, the impact on the properties of concrete, are described. The RBA has been treated to decrease the water absorption capacity by impregnation approach using specific impregnators. Afterwards, the RBA samples have been dried at two different temperatures in the laboratory oven—20 and 90 °C. Concretes using 4/8 fraction of the treated RBA instead of natural aggregate (NA) have been mixed and tested. The effectiveness of the RBA treatments have been evaluated on the basis of their influence on the properties of the hardened concrete; by means of the following tests: flexural strength, compressive strength, capillarity, total water absorption capacity, depth of water penetration under pressure, and frost resistance. The method of ranking by ordinal scale has been used as it is suitable for the comparison of a large set of results, while results have been analyzed in terms of the most important technological parameter that influences the quality of the concrete-effective water content. Out of all the tested surface-treatments of RBA, treatment by sodium water glass has the best potential for reduction of the water/cement (w/c) ratio. When the effective w/c ratio is kept within standard limits, concretes containing treated RBA are possible to be specified for various exposure classes and manufacturing in practice. The experiment confirms that at a constant amount of mixing water, with decreasing water absorption of RBA, the effective amount of water in the concrete increases and, hence, the final properties of the concrete decrease (get worse). As the water absorption of the RBA declines, there is a potential for the reduction of the w/c ratio and improvement in the quality of the concrete.

Relationship between acidification factors and methylene blue uptake by Ca-bentonite: optimisation and kinetic study

This investigation studied the uptake of methylene blue from wastewater by normal and treated bentonites to evaluate the effects of acidification factors on removal efficiency. Hydrochloric, sulphuric and nitric acids were blended in accordance with the response surface methodology to prepare acidic agents. The normal clay was then mixed with the prepared solutions after drying in a laboratory oven. The set-up provided controllable conditions for producing nano-porous powders for which the residence time and temperature were changed. The removal efficiency of the treated powders was assessed by defining an adsorption ratio and determining the optimal composition for acidic agent. Based on the statistical theory and experimental data, nitric acid is a suitable agent for manufacturing porous material to remove methylene blue from wastewater. In addition, the Brunauer–Emmett–Teller method, X-ray diffraction and Fourier transform infrared spectroscopy techniques were applied to identify the structural changes. The experimental data obtained from the batch tests were analysed by a new kinetic model which predicted the data variation with higher regression coefficients and lower relative errors. The proposed procedure can be an important tool in optimising the acidification conditions for manufacturing a nano-porous powder with maximal removal efficiency.

Drying Curves and Colour Changes of Cassia Alata Leaves at Different Temperatures

Cassia alata plant has been commonly used as medicinal herbs for treating fungal infection such as ringworm and eczema. Nevertheless, a few studies on drying characteristics have focused on C. alata. This work aims to investigate the drying characteristics of C. alata leaves at different temperatures. Moreover, the effects of different drying temperatures on colour qualities of C. alata leaves had been determined. The leaves were dried at different temperatures (40, 50, 60, 70, 80 and 90 °C) using a laboratory oven. Dried and fresh leaves were analyzed for the moisture content and colour analysis. The EMC of C. alata leaves decreased from 0.30 to 0.10 g water/dry matter as the temperature increased from 40 °C to 90 °C. The colour qualities of C. alata leaves were lower with increasing drying temperature.

Waste poly (vinyl chloride) pyrolysis with hydrogen chloride abatement by steelmaking dust

AbstractExperimental study on PVC-based materials (PVC = poly (vinyl chloride)) pyrolysis; in the presence of various amounts of steelmaking dust was performed. Dust from steel manufacture employing zinc plated scrap contains a considerable amount of zinc oxide (ZnO) and its utilization in metallurgy is quite complicated. However, the dust can react with hydrogen chloride (HCl) released from heated PVC in the temperature range of 200–400°C. Material balance of the pyrolysis process was studied by thermogravimetry, and the data obtained were compared with the results of larger laboratory oven experiments. In excess of PVC, the amount of captured HCl stoichiometrically corresponds to the content of ZnO; additional HCl is probably captured by FeCl

Easy Method for Removal of Cyanogens from Cassava Leaves with Retention of Vitamins and Omega-3 Fatty Acids

Currently there is a crescent interest regarding the use of vegetable by-products for food fortification, in order to improve its nutritional quality. Cassava leaves are suitable as nutritional additives, however their cyanide content must be reduced to below 10 mg kg-1 of dry product. Thus, it was developed a method in drying laboratory oven which is able to reduce 99.85% of cyanide present in manioc leaves (from 35 mg kg-1 to 0.05 mg kg-1) while being 509% faster than the traditional method, and without substantial loss of omega-3 fatty acids and β-carotene.

CHARACTERISATION OF CASSAVA BAGASSE IN DIFFERENT GRANULOMETRIES FROM TWO STARCH PROCESSING PLANTS

Cassava is an agricultural crop that occupies an important place in the diet of people of many countries in tropical and sub-tropical regions. Cassava bagasse is a by-product from industrial processing that is generated in great quantities and it can exhibit about 40-50 % of starch in its composition, in dry basis. Two samples, one moist (sample A) and another dry (sample B), were supplied by two cassava starch industries. The samples were analysed by physicochemical, thermoanalytical (TG, DTA, DSC), rheological (RVA) and micro-structural methods (NC-AFM) that demonstrated that the temperature of the industrial drying (around 150 ºC) was not very well controlled, reaching higher temperatures, reaching decomposition of organic matter condition causing changes (please specify) and browning. Although it was milled, sieved and contained 41.31 (0.43) % of starch, sample B did not present gelatinisation or paste properties. Sample A, with 47.75 (0.21) % of starch, dried carefully in a laboratory oven with forced air circulation at 45 ºC for 24 hours showed gelatinisation enthalpy (Hgel) and viscosity with values directly proportional to the granulometry.

Very high strength (120 MPa) class F fly ash geopolymer mortar activated at different NaOH amount, heat curing temperature and heat curing duration

In this laboratory work, high compressive and flexural tensile strength of alkali activated fly ash geopolymer mortars were presented. Class F fly ash was used throughout the study. NaOH was used as alkali medium that provides high pH value. Also, the factors influencing the compressive and flexural tensile strength were investigated. A total of 216 fly ash geopolymer mortar samples were prepared. Heat curing temperature, heat curing duration and alkali (Na) concentration were chosen as the influencing parameters of strengths. Mortar mixture parameters were 3 and 1/3 for sand–binder ratio, and water–binder ratio, respectively. Na concentrations of the mortar mixtures were changed from 4% to 20% with 2% increment step. Heat curing temperatures were changed from 45 to 115°C with 10°C increment step. Heat curing durations were chosen as 24, 48 and 72h. For each combination of influencing parameter, three prismatic specimens with 40mm×40mm×160mm dimensions were prepared using a three-cell mortar cast. After heat curing period in a laboratory oven, the samples were left to cool down to room temperature, then compressive and flexural strengths were measured as described in its respective standard. Very high compressive and flexural tensile strength obtained, which were as high as 120 and 15MPa respectively.

Green approach for the synthesis and characterization of ZrSnO4 nanopowder

Well-defined structural framework of ZrSnO4 nanopowder has been synthesized for the fabrications of cost-effective and sensitive devices which give final reproducible result with reliability under ideal conditions. The synthesis was carried out at moderate temperature and then finally dried in the laboratory oven and then followed with calcination at 1000 °C for 4 h to get phase selective product. It was observed that gelation time depends on the concentration of reactants and temperature. The characterization of ZrSnO4 was carried out with XRD, SEM, TEM, UV, thermal analysis, DLS and FT-IR techniques. With adjustment of reaction parameters, the systematic tuning of the particle size, shape and functional properties can be controlled. It was concluded that self-assembly is an integral part for the synthesis and opens a new exciting opportunity for better understanding the formation of nanostructure framework from micro- to nanoscale along with mechanistic via wet chemical approach. ZrSnO4 has vital role in identifying its potential cytotoxicity in the biological systems. The cytotoxicity effects of ZrSnO4 nanopowder in vitro were evaluated in three different human cell types (hepatocytes, mesenchymal stem cells and neuronal cells). Acute exposure of nanoparticles was found to have greater cytotoxic effect at higher concentration (30 µg/ml). However, partial detoxification was observed during nanoparticles exposure at day 6. The study concluded that an initial stress from nanoparticles incorporates sealing or detoxification of nanoparticles which may help to recover cell viability.

Capacitive sensor probe to assess frying oil degradation

The repeated usage of frying oil has been proven hazardous due to the degradation process by chemical reactions that lead to changes in the quality of the oil. Currently, the degree of frying oil degradation is indicated by the percentage of its total polar compounds (TPC). In this study, a capacitive sensor was designed to assess frying oil degradation at several heating time intervals by measuring changes on its electrical capacitance. The sensor was designed using interdigitated electrode structure. A total of 30 samples of 130ml palm oil were heated at 180°C up to 30h. For each one hour interval, one sample was moved out from the laboratory oven. The electrical capacitance, total polar compound (TPC) and viscosity of the samples were measured for analysis. Preliminary results demonstrated significant correlation between oil electrical capacitance with TPC and viscosity with R2 ranged from 0.83 to 0.90. The designed sensor has good potential for simple and inexpensive way of determining frying oil quality.

Antioxidant, Total Lycopene, Ascorbic Acid and Microbial Load Estimation in Powdered Tomato Varieties Sold in Dutsin-Ma Market

Tomato varieties sold in Dutsin-Ma market namely, UTC, Rukuta and Dan-Aka were subjected to drying in a laboratory oven, solar drier and under direct sunlight then, powdered. The antioxidant and total lycopene contents were examined and found to be unaffected by the three drying procedures, with values ranging between 68.46% ± 0.90% to 80.77% ± 1.11% and 123.63 to 161.98 mg/kg, respectively. The ascorbic acid was also tested and values were significantly lower in all the samples subjected to sun-drying with values ranging from 17.78 ± 1.78 μg/ml to 28.44 ± 1.78 μg/ml as against 100.15 ± 1.03 μg/ml to 164.74 ± 2.06 μg/ml for oven and solar dried tomato samples (p < 0.05), respectively. Total microbial load, yeast/mould, and coliform counts were then investigated. They were too numerous to count (TNTC) in the sun-dried samples. Although, also found among samples that were oven and solar dried, counts of the microorganisms were within the acceptable standards of <105 for bacteria and 103 - 104 for fungi. While solar and oven drying presented better preservation of the tomato samples, the former offers most incentive in terms of cost and quality to farmers and the people, considering its free availability and abundance in processing dry tomato powders.

Baking sunflower hulls within an aluminum envelope in a common laboratory oven yields charcoal

Charcoals have been widely used by scientist to research the removal of contaminants from water and air. One key feature of charcoal is that it keeps macropores from the parent material – though anisotropically contracted – and can even develop meso- and micropores. However, the controlled thermochemical conversion of biomass into charcoal at laboratory scale normally requires special setups which involve either vacuum or inert gas. Those setups may not be affordable in research groups or educational institutions where the research of charcoals would be highly welcome. In this work, I propose a simple and effective method to steer the thermochemical process that converts sunflower hulls (SFH) into charcoal with basic laboratory resources.The carbonization method:•Place SFH in an airtight aluminum envelope.•Thermally treat SFH within the envelope in a common laboratory oven.•Open the envelope to obtain the carbonized sunflower hulls.