Effect of moisture and temperature distribution on dried food microstructure and porosity

Dehydration of food materials requires water removal from it. This removal of moisture prevents the growth and reproduction of microorganisms that cause decay and minimizes many of the moisture-driven deterioration reactions (Brennan, 1994). However, during food drying, many other changes occur simultaneously resulting in a modified overall quality (Kompany et al., 1993). Among the physical attributes of dried food material porosity and microstructure are the important ones that can dominant other quality of dried foods (Aguilera et al., 2000). In addition, this two concerned quality attributes affected by process conditions, material components and raw structure of food stuff. In this work, temperature moisture distribution within food materials during microwave drying will be taken into consideration to observe its participation on the microstructure and porosity of the finished product. Apple is the selective materials for this work. Generally, most of the food materials are found in non-uniformed moisture contained condition. To develop non uniform temperature distribution, food materials have been dried in a microwave oven with different power levels (Chua et al., 2000). First of all, temperature and moisture model is simulated by COMSOL Multiphysics. Later on, digital imaging camera and Image Pro Premier software have been deployed to observation moisture distribution and thermal imaging camera for temperature distribution. Finally, Microstructure and porosity of the food materials are obtained from scanning electron microscope and porosity measuring devices respectively . Moisture distribution and temperature during drying influence the microstructure and porosity significantly. Specially, High temperature and moisture contained regions show less porosity and more rupture. These findings support other literatures of Halder et al. (2011) and Rahman et al (1990). On the other hand, low temperature and moisture regions depict uniform microstructure and high porosity. This work therefore assists in better understanding of the role of moisture and temperature distribution to a prediction of micro structure and porosity of dried food materials.

A study of the diffusion characteristics of normal, delipidized and relipidized articular cartilage using magnetic resonance imaging

This paper assesses the capacity to provide semipermeability of the synthetic layer of surface-active phospholipids created to replace the depleted surface amorphous layer of articular cartilage. The surfaces of articular cartilage specimens in normal, delipidized, and relipidized conditions following incubation in dipalmitoyl-phosphatidylcholine and palmitoyl-oleoyl-phosphatidylcholine components of the joint lipid mixture were characterized nanoscopically with the atomic force microscope and also imaged as deuterium oxide (D2O) diffused transiently through these surfaces in a magnetic resonance imaging enclosure. The MR images were then used to determine the apparent diffusion coefficients in a purpose-built MATLAB®-based algorithm. Our results revealed that all surfaces were permeable to D2O, but that there was a significant difference in the semipermeability of the surfaces under the different conditions, relative to the apparent diffusion coefficients. Based on the results and observations, it can be concluded that the synthetic lipid that is deposited to replace the depleted SAL of articular cartilage is capable of inducing some level of semipermeability.

Thermal treatment of natural goethite : thermal transformation and physical properties

XRD (X-ray diffraction), XRF (X-ray fluorescence), TG (thermogravimetry), FT-IES (Fourier transform infrared emission spectroscopy), FESEM (field emission scanning electron microscope), TEM (transmission electron microscope) and nitrogen–adsorption–desorption analysis were used to characterize the composition and thermal evolution of the structure of natural goethite. The in situ FT-IES demonstrated the start temperature (250 °C) of the transformation of natural goethite to hematite and the thermodynamic stability of protohematite between 250 and 600 °C. The heated products showed a topotactic relationship to the original mineral based on SEM analysis. Finally, the nitrogen–adsorption–desorption isotherm provided the variation of surface area and pore size distribution as a function of temperature. The surface area displayed a remarkable increase up to 350 °C, and then decreased above this temperature. The significant increase in surface area was attributed to the formation of regularly arranged slit-shaped micropores running parallel to elongated direction of hematite microcrystal. The main pore size varied from 0.99 nm to 3.5 nm when heating temperature increases from 300 to 400 °C. The hematite derived from heating goethite possesses high surface area and favors the possible application of hematite as an adsorbent as well as catalyst carrier.

Gene electrotransfer into murine skeletal muscle: A systematic analysis of parameters for long-term gene expression

Skeletal muscle is an attractive target tissue for delivery of therapeutic genes, since it is well vascularized, easily accessible, and has a high capacity for protein synthesis. For efficient transfection in skeletal muscle, several protocols have been described, including delivery of low voltage electric pulses and a combination of high and low voltage electric pulses. The aim of this study was to determine the influence of different parameters of electrotransfection on short-term and long-term transfection efficiency in murine skeletal muscle, and to evaluate histological changes in the treated tissue. Different parameters of electric pulses, different time lags between plasmid DNA injection and application of electric pulses, and different doses of plasmid DNA were tested for electrotransfection of tibialis cranialis muscle of C57BI/6 mice using DNA plasmid encoding green fluorescent protein (GFP). Transfection efficiency was assessed on frozen tissue sections one week after electrotransfection using a fluorescence microscope and also noninvasively, followed by an in vivo imaging system using a fluorescence stereo microscope over a period of several months. Histological changes in muscle were evaluated immediately or several months after electrotransfection by determining infiltration of inflammatory mononuclear cells and presence of necrotic muscle fibers. The most efficient electrotransfection into skeletal muscle of C57BI/6 mice in our experiments was achieved when one high voltage (HV) and four low voltage (LV) electric pulses were applied 5 seconds after the injection of 30 μg of plasmid DNA. This protocol resulted in the highest short-term as well as long-term transfection. The fluorescence intensity of the transfected area declined after 2-3 weeks, but GFP fluorescence was still detectable 18 months after electrotransfection. Extensive inflammatory mononuclear cell infiltration was observed immediately after the electrotransfection procedure using the described parameters, but no necrosis or late tissue damage was observed. This study showed that electric pulse parameters, time lag between the injection of DNA and application of electric pulses, and dose of plasmid DNA affected the duration of transgene expression in murine skeletal muscle. Therefore, transgene expression in muscle can be controlled by appropriate selection of electrotransfection protocol.

A large proportion of asymptomatic Plasmodium infections with low and sub-microscopic parasite densities in the low transmission setting of Temotu Province, Solomon Islands : challenges for malaria diagnostics in an elimination setting

Background Many countries are scaling up malaria interventions towards elimination. This transition changes demands on malaria diagnostics from diagnosing ill patients to detecting parasites in all carriers including asymptomatic infections and infections with low parasite densities. Detection methods suitable to local malaria epidemiology must be selected prior to transitioning a malaria control programme to elimination. A baseline malaria survey conducted in Temotu Province, Solomon Islands in late 2008, as the first step in a provincial malaria elimination programme, provided malaria epidemiology data and an opportunity to assess how well different diagnostic methods performed in this setting. Methods During the survey, 9,491 blood samples were collected and examined by microscopy for Plasmodium species and density, with a subset also examined by polymerase chain reaction (PCR) and rapid diagnostic tests (RDTs). The performances of these diagnostic methods were compared. Results A total of 256 samples were positive by microscopy, giving a point prevalence of 2.7%. The species distribution was 17.5% Plasmodium falciparum and 82.4% Plasmodium vivax. In this low transmission setting, only 17.8% of the P. falciparum and 2.9% of P. vivax infected subjects were febrile (≥38°C) at the time of the survey. A significant proportion of infections detected by microscopy, 40% and 65.6% for P. falciparum and P. vivax respectively, had parasite density below 100/μL. There was an age correlation for the proportion of parasite density below 100/μL for P. vivax infections, but not for P. falciparum infections. PCR detected substantially more infections than microscopy (point prevalence of 8.71%), indicating a large number of subjects had sub-microscopic parasitemia. The concordance between PCR and microscopy in detecting single species was greater for P. vivax (135/162) compared to P. falciparum (36/118). The malaria RDT detected the 12 microscopy and PCR positive P. falciparum, but failed to detect 12/13 microscopy and PCR positive P. vivax infections. Conclusion Asymptomatic malaria infections and infections with low and sub-microscopic parasite densities are highly prevalent in Temotu province where malaria transmission is low. This presents a challenge for elimination since the large proportion of the parasite reservoir will not be detected by standard active and passive case detection. Therefore effective mass screening and treatment campaigns will most likely need more sensitive assays such as a field deployable molecular based assay.

Mechanism of kaolinite sheets curling via the intercalation and delamination process

Kaolinite naturally occurs in the plate form for the interlayer hydrogen bond and the distortion and adaption of tetrahedron and octahedron. But kaolinite sheets can be exfoliated to nanoscrolls artificially in laboratory through multiple-step displacement intercalation. The driving force for kaolinite sheet to be curled nanoscroll originates from the size discrepancy of Si–O tetrahedron and Al–O octahedron. The displacement intercalation promoted the platy kaolinite sheets spontaneously to be scrolled by eliminating the interlayer hydrogen bond and atomic interaction. Kaolinite nanoscrolls are hollow tubes with outer face of tetrahedral sheet and inner face of octahedral sheet. Based on the theoretical calculation it is firstly reported that the minimum interior diameter for a single kaolinite sheet to be scrolled is about 9.08 nm, and the optimal 24.30 nm, the maximum 100 nm, which is verified by the observation of scanning electron microscope and transmission electron microscope. The different adaption types and discrepancy degree between tetrahedron and octahedron generate various curling forces in different directions. The nanoscroll axes prefer the directions as [100], [1 �10], [110], [3 �10], and the relative curling force are as follows, [3 �10] > [100] = [1�10] > [110].

Corrosion studies on the plasma-sprayed nanostructured titanium dioxide coating

Purpose: The purpose of this paper is to report the resistance of plasma-sprayed titanium dioxide (TiO2) nanostructured coatings in a corrosive environment.----- Design/methodology/approach: Weight loss studies are performed according to ASTM G31 specifications in 3.5?wt% NaCl. Electrochemical polarization resistance measurements are made according to ASTM G59-91 specifications. Corrosion resistance in a humid and corrosive environment is determined by exposing the samples in a salt spray chamber for 100?h. Microstructural studies are carried out using an atomic force microscope and scanning electron microscope.----- Findings: The nanostructured TiO2 coatings offer good resistance to corrosion, as shown by the results of immersion, electrochemical and salt spray studies. The corrosion resistance of the coating is dictated primarily by the geometry of splat lamellae, density of unmelted nanoparticles, magnitude of porosity and surface homogeneity.----- Practical implications: The TiO2 nanostructured coatings show promising potential for use as abrasion, wear-resistant and thermal barrier coatings for service in harsh environments.----- Originality/value: The paper relates the corrosion resistance of nanostructured TiO2 coatings to their structure and surface morphology.

Neutrophilic, microaerophilic Fe(II)-oxidizing bacteria are ubiquitous in aquatic habitats of a subtropical Australian coastal catchment (ubiquitous FeOB in catchment aquatic habitats)

We examined the abundance and distribution of neutrophilic, microaerophilic Fe(II)-oxidizing bacteria (FeOB) in aquatic habitats of a highly weathered, subtropical coastal catchment where Fe biogeochemistry is of environmental significance. Laboratory cultivation and microscopy indicated that stalked Gallionella and sheathed Leptothrix-like FeOB were present in microbial mats associated with a circumneutral-pH, groundwater seep and streambank surface sediment,whereas unicellular FeOB werewidespread in surface and subsurface waters, including a seep, shallow stream and estuary-adjacent groundwater. Direct Gallionella-specificPCR detected dominant bacterial members related to Sideroxydans paludicola (95% sequence identity, SI) and Gallionella capsiferriformans (96% SI) in the seep microbialmat. TGGE analysis indicated that themost common FeOB in water enrichment cultures were related to S. lithotrophicus (96% SI). The ubiquity of FeOB in Poona catchment aquatic habitats suggests bacterial Fe(II) oxidation is integral to catchment Fe biogeochemistry.

Korean ubiquitous-eco-city : a smart-sustainable urban form or a branding hoax?

The buzzwords of zero-carbon, low-carbon, carbon-neutral, smart-eco and ubiquitous-eco have become common brands for the sustainable eco-cities of the 21st century. This paper focuses on one of these city types ‘ubiquitous-eco-city’ (u-eco-city). The principal premise of a u-eco-city is to provide a high quality of life and place to residents, workers and visitors with low-to-no negative impacts on the natural environment by using state-of-the-art technologies in the planning, development and management stages. The paper aims to put this premise into a test and address whether u-eco-city is a dazzling smart and sustainable urban form that constitutes an ideal 21st century city model or just a branding hoax. This paper explores recent developments and trends in the ubiquitous technologies, infrastructures, services and management systems, and their utilisation and implications for the development of u-eco-cities. The paper places Korean u-eco-city initiatives under microscope, and critically discusses their prospects in forming a smart and sustainable urban form and become an ideal city model.

Dependence of second-harmonic signals generated in malignant human prostate tissue on excitation wavelength

The dependence of second harmonic generation (SHG) from hyperplastic parenchyma and stroma in maligant human prostate tissue on excitation wavelengths was measured. A femtosecond pulsed laser, a scanning microscope and a spectrograph were used to perform the measurements. The spectra were measured under excitation power of 10 mW at excitation wavelengths of 730 nm, 750 nm, 800 nm, 850 nm and 890 nm. Analysis suggested that the SHG in prostate tissue is highly structured and wavelength dependent signifying its ability to be used as an indicator for recognizing tissue components, ultrastructures, micro-environments and diseases.

Structural-stratigraphic reconstruction of the lower Whakataki formation, north island, New Zealand

This thesis details a Miocene aged sedimentary rock formation located in north island New Zealand. Mapping, stratigraphic logging and petrographic analysis of the rock formation ascertained that it was deposited in a deep-marine, tectonically active region. The work details the make-up of the sedimentary rocks using geochemistry and microscopy to define their origin. This definition was used to interpret the depositional model of the sediments detailing how they were transported and how they were emplaced.

In Situ Observation of the Thermal Decomposition of Weddelite by Heating Stage Environmental Scanning Electron Microscopy

The morphological and chemical changes occurring during the thermal decomposition of weddelite, CaC2O4·2H2O, have been followed in real time in a heating stage attached to an Environmental Scanning Electron Microscope operating at a pressure of 2 Torr, with a heating rate of 10 °C/min and an equilibration time of approximately 10 min. The dehydration step around 120 °C and the loss of CO around 425 °C do not involve changes in morphology, but changes in the composition were observed. The final reaction of CaCO3 to CaO while evolving CO2 around 600 °C involved the formation of chains of very small oxide particles pseudomorphic to the original oxalate crystals. The change in chemical composition could only be observed after cooling the sample to 350 °C because of the effects of thermal radiation.