Implant surface features as key role on cell behavior

It has been recognized that physical and chemical properties of biomaterial surfaces mediate the quality of extracellular matrix (ECM) that may affect cell behaviors. In nature, ECM is a heterogeneous three-dimensional superstructure formed by three major components, glycosaminoglycan, glycoconjugate, and protein, that anchors cellular compartments in tissues and regulates the function and the behavior of cells. Changes in the biointerface alter the quality of ECM and morphology through cell surface receptors, which, in turn, enable it to trigger specific cell signaling and different cellular responses. In fact, a number of strategies have been used to improve the functionality of surfaces and direct cell behavior through precisely designed environments. Herein, we aimed to discuss, through a science-based viewpoint, the biomaterial surface features on cell behavior and analyze the impact of cell physical modification on dental implant development.     

MODELING OF PREHEAT TREATMENT OPTIMIZATION APPLIED TO FRESH‐CUT “ROCHA” PEAR

ABSTRACT

Response surface methodology based on a five‐level, three‐variable central composite rotatable design was used for modeling the effects of preheat treatments on fresh‐cut “Rocha” pear quality. Studied variables were time (t: 0–150 min), temperature (T: 20–50C) and posttreatment storage time (St: 0–20 days, 5C). The quality‐affecting parameters including color, firmness, pH, soluble solid content, and total ascorbic acid content were the monitored dependent variables. Results provide reasonable estimation of the impact of preheat treatments on the quality of fresh‐cut “Rocha” pear and its shelf life. The time–temperature range of 33–41C during less than 20 min was selected as the conditions that best provided surface browning control, without impairing other studied quality parameters, with an estimated 8‐day shelf life period. The achieved kinetic changes of polyphenoloxidase, partial reduction in enzyme activity (ca. 23%) and depletion of phenolic content (ca. 11%) could be responsible for the browning control.

PRACTICAL APPLICATIONS

Minimal processing, namely cutting operations, triggers physiological reactions which limit fresh‐cut Rocha pear shelf life. Superficial browning is one of the major concerns to this industry, and new “clean” methodologies aiming at the inhibition of such reaction and maximization of the product shelf life will benefit not only from product marketability but also will respond to the consumers' demand of “chemical free” products. Heat treatments have been used to improve fresh‐cut commodities' browning resistance. The present work evaluated the use of preheat treatments against this physiological disorder during storage. Results will provide an optimized preheat treatment that grants high‐quality fresh‐cut Rocha pear with suitable shelf life.

     

ANTIOXBDANT PROPERTIES OF OREGANO (ORIGANUM VULGARE) LEAF EXTRACTS

We tested the antioxidant properties of both aqueous and methanolic extracts of oregano (origanum vulgare) They proved to be effective in the inhibition of all phases of the peroxidative process: first neutralizing free radicals (superoxide anion, hydroxyl radical and 1,1‐diphenyl‐2‐picrylhydrazyl radical), then blocking peroxidation catalysis by iron (through iron‐chelating and iron‐oxidizing properties), and finally through interruption of lipid‐radical chain reactions (chain‐breaking activity). Their anti‐glycosylation activity was also effective. The glycosylation oflipoproteins is directly related to their peroxidation. The amount of extract used in our experiments was obtained from 0.1–1 mg of dried leaves, amounts far less than those normally used in the Mediterranean diet.     

ANALYTICAL PREDICTION OF DRYING PERFORMANCE IN NONCONVENTIONAL SHAPES

A study is made to develop a tool to predict drying performance of nonconventional shapes. Many food drying processes are diffusion-controlled. An approximated analytical solution to Fick's diffusion equation is given for bodies which have a cardioidal, corrugated, circular, epitrochoidal, square, or hexagonal cross section. A conformal mapping approach is used to obtain the concentration distribution and the result is integrated over the volume to yield analytical weight loss equations for each shape. The result is applied to compare drying performance of apples on an equal weight-equal cross sectional area or an equal weight-equal thickness basis.     

ROLE OF WATER IN THE KINETIC MODELING OF METHANOL TRANSFORMATION INTO HYDROCARBONS ON HZSM-5 ZEOLITE

The attenuating effect of reaction-medium water (feed and/or reaction product) on the kinetics of the steps of methanol transformation into hydrocarbons on a HZSM-5 zeolite catalyst was studied by means of a kinetic model. In this model, the effect of water was quantified in all the steps of the kinetic scheme by means of a kinetic parameter, which is constant with temperature under the conditions of the MTG process. At low temperature, under conditions in which only methanol dehydration occurs, the kinetics of this reaction is attenuated by the presence of water, and the coefficient that quantifies the attenuation decreases as temperature is increased. In addition to considering the effect of water content in the reaction medium, another innovation of the kinetic model proposed, compared to those proposed in the literature consisting of lumps, is the fact that the higher reactivity of dimethyl ether over methanol is taken into account. A step of cracking of gasoline lump hydrocarbons to produce light olefins (ethene and propene) was also taken into account. The kinetic model proposed was verified by using the results obtained in an integral isothermal fixed bed reactor, in the 573–723 K range, for an ample range of space time values. The results revealed that the effect of water is due to its adsorption on the active sites by competition with the intermediate compounds of the kinetic scheme.     

Modified Dry Column Procedure for Extraction of Lipids from Cured Meats

Polar lipids extracted from heated, nitrite-treated meats by a dry column procedure contain pigmented contaminants that interfere with subsequent analyses. Three modifications to the standard extraction procedure were studied: (a) changes in the composition of the trap, (b) insertion of additional material between column proper and trap, and (c) changes in the solvent system. Most satisfactory results were obtained by the addition of magnesium oxide to the trap (I). This resulted in the retention of impurities on the column and provided convenient, trouble-free operation. Polar lipids isolated in this manner were free of peroxides. Uncontaminated lipids were extracted from commercially processed meats by use of the modified procedure.     

Frozen Hake Fillets Quality as Related to Texture and Viscosity By Mechanical Methods

This work aimed to develop a textural quality classification function for frozen hake fillets using instrumental measurements. Frozen hake fillets were stored to provide a wide range of textures. Raw and cooked fillets were analyzed for texture using Kramer and Warner-Bratzler shear cells and a puncture device. Apparent viscosity, dimethylamine and protein solubility were also measured. Principal Component Analysis indicated three factors accounted for 86.5% of the variance. Four clusters were found, ranging from excellent quality (low texture, high viscosity) to very poor (high texture, low viscosity). Parameters required for classification were viscosity, maximum force from Kramer and maximum force and energy from the puncture test.     

VISCOSITY and SURFACE TENSION of CORN OIL AT FRYING TEMPERATURES

Surface active properties and viscosity changes of corn oil were determined under controlled frying conditions. Viscosity of corn oil was measured at a temperature range of 100–200C. Surface-active properties of thermally degraded corn oil were determined by measuring the stationary contact angle () of oil droplets placed on a low energy surface (polystyrene). the viscosity of oil decreased as temperature increased. At 200C, the kinematic viscosity had decreased 69% when compared with its initial value of 7.50 mm²/s at 100C. Oil was degraded by frying 400 g of potatoes for 5 min each hour for 36 h (low load frying). the experiment was repeated with 1200g of potatoes (high load frying). the viscosity of the oil increased 9.4% and 28.6% for low and high load fryings, respectively. the surface tension of the oil and its degradation time were inversely proportional (at high load frying) lowering the surface tension of the oil by 2.0%. A high correlation (r²= 0.90) between the viscosity and surface tension of oil was obtained.