Antibacterial activity of chlorhexidine after final irrigation with ethanol: CLSM and culture‐based method analysis

This study investigated the effect of 95% ethanol on the antibacterial properties of 2% chlorexidine (CHX) over monospecies biofilm (Enterococcus faecalis) through a culture‐based method, and over multispecies biofilm using confocal laser scanning microscopy (CLSM). For monospecies model, E. faecalis biofilm was induced in 40 root canals. The irrigation procedures were: S—saline solution; S/CHX—saline solution + CHX; E—ethanol; and E/CHX—ethanol + CHX. Microbial sampling was performed at three periods: before (S1), immediately after (S2), and 72 h after the final flush (S3). For multispecies biofilm model, 28 sterilized bovine dentin blocks were fixed on a removable orthodontic device to allow intraoral biofilm development. Seven samples were used in each group. Statistical analysis was carried out by using the Kruskal–Wallis test and Dunn's test for multiple comparisons. There was a significant reduction in CFUs count immediately after the final flush (S2) in all experimental groups (P < 0.05). However, only S/CHX, E and E/CHX groups had CFU counts close to zero, without differences among them (P > 0.05). After 72h (S3), the S/CHX and E/CHX groups had CFU counts near zero (P > 0.05). The CFU count increased in S3 for S and E groups (P < 0.05). CLSM showed that the percentages of remaining live cells were similar in S/CHX, E, and E/CHX groups (P > 0.05). The S group had the highest percentage of live cells (P < 0.05). The 95% ethanol did not interfere in the antibacterial properties of 2% CHX over mono‐ and multispecies biofilms. Microsc. Res. Tech. 78:682–687, 2015. © 2015 Wiley Periodicals, Inc.     

Effects of EPDM‐g‐MAH compatibilizer and internal mixer processing parameters on the properties of NR/EPDM blends: An analysis using response surface methodology

This study evaluates the effects of ethylene‐propylene‐diene‐monomer grafted maleic anhydride (EPDM‐g‐MAH) and internal mixer melt compounding processing parameters on the properties of natural rubber/ethylene‐propylene‐diene rubber (NR/EPDM) blends. Using Response Surface Methodology (RSM) of 2⁵ two‐level fractional factorial, we studied the effects of NR/EPDM ratio, mixing temperature, Banbury rotor speed, mixing period, and EPDM‐g‐MAH contents in NR/EPDM blends. The study found that the presence of EPDM‐g‐MAH in NR/EPDM blends had a predominant role as a compatibilizing agent, which affected the processability and properties of the final material. We also determined the model fitting with constant determination, R² of 99.60% for tensile strength (TS) response with a suggested combination of mixing process input parameters. The reproducibility of the proposed mixing strategy was then confirmed through model validation with a minor deviation at +2.303% and higher desirability of 0.960. This study is essential in providing a process design reference for NR/EPDM blends preparation by melt‐blending and the role of a compatibilizer from the systematic Design of Experiment (DOE) approach. The experimental findings were further supported with swelling and cross‐link density measurements, differential scanning calorimetry analysis, and observation of fracture morphology using a scanning electron microscope. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42199.     

Improved impact strength of epoxy by the addition of functionalized multiwalled carbon nanotubes and reactive diluent

Multiwalled carbon nanotubes (MWCNTs), both oxidized and amine functionalized (triethylenetetramine—TETA), have been used to improve the mechanical properties of nanocomposites based on epoxy resin. The TGA and XPS analysis allowed the evaluation of the degree of chemical modification on MWCNTs. Nanocomposites were manufactured by a three‐roll milling process with 0.1, 0.5, and 1.0 wt % of MWCNT–COOH and MWCNT–COTETA. A series of nanocomposites with 5.0 wt % of reactive diluent was also prepared. Tensile and impact tests were conducted to evaluate the effects of the nanofillers and diluent on the mechanical properties of the nanocomposites. The results showed higher gains (258% increase) in the impact strength for nanocomposites manufactured with aminated MWCNTs. Optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to investigate the overall filler distribution, the dispersion of individual nanotubes, and the interface adhesion on the nanocomposites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42587.     

Facile preparation of carbon coated magnetic Fe3O4 particles by a combined reduction/CVD process

In this work, we report a simple method for the preparation of magnetic carbon coated Fe₃O₄ particles by a single step combined reduction of Fe₂O₃ together with a Chemical Vapor Deposition process using methane. The temperature programmed reaction monitored by Mössbauer, X-ray Diffraction and Raman analyses showed that Fe₂O₃ is directly reduced by methane at temperatures between 600 and 900 °C to produce mainly Fe₃O₄ particles coated with up to 4 wt% of amorphous carbon. These magnetic materials can be separated into two fractions by simple dispersion in water, i.e., a settled material composed of large magnetic particles and a suspended material composed of nanoparticles with an average size of 100-200 nm as revealed by Scanning Electron Microscopy and High-resolution Transmission Electron Microscopy. Different uses for these materials, e.g., adsorbents, catalyst supports, rapid coagulation systems, are proposed.     

Affect of adhesion and properties of kenaf (Hibiscus cannabinus L.) stem in particleboard performance

The objective of this work was to evaluate the adhesion and basic properties of kenaf stem, and its physical and mechanical properties on particleboard panels. In this study, rubberwood (RW) was used as a control. Single-layer experimental panels were produced from whole stem, core, and bast particles of kenaf. Findings revealed that the core part resulted in higher wettability and lower contact angle than the bast. Kenaf bast (KB) gave the highest buffering capacity, while kenaf core (KC) gave the lowest buffering capacity towards acid. The lowest specific gravity was shown by KC followed by kenaf whole stem (KWS) and KB. For particle analysis, KWS gave the highest acceptable particle distribution (73.9%), whilst KC, KB, and RW had particle distributions of 62.5, 68.1, and 56.8%, respectively. Particleboard panels produced from KWS had the highest average values of modulus of rupture and modulus of elasticity with good compaction under scanning electron microscopic. Panels made from bast particles had the lowest mechanical properties among the three types of panels. The internal bonding strengths and dimensional stability of the specimens followed the similar trend above. The results of this study indicate that the specific gravity and adhesion properties of the starting material play a role in determining the physical and mechanical properties of the particleboard panels.     

Effects of conventional and ultrasound blanching on enzyme inactivation and carbohydrate content of carrots

There is a growing interest in the use of ultrasound (US) as an alternative to conventional processes. Although US has previously been applied as a pretreatment of fruits and vegetables, no investigation has been done on the usefulness of US for carrot blanching, paying special attention to its effect on enzyme inactivation and leaching losses. In the present paper, the influence of US (in bath and with probe) on peroxidase (POD) and pectinmethylesterase (PME) inactivation and on the loss of total soluble solids and carbohydrates by leaching has been evaluated. Results of this preliminary study have also been compared with those obtained after conventional (hot water and steam) blanching of carrots. The highest enzyme inactivation was obtained with the conventional treatments performed at high temperatures and with the US probe treatments with heat generation. Carrots blanched by US probe for 10?min at a temperature up to 60?°C showed characteristics similar to those conventionally treated at 60?°C for 40?min. Although the efficiency of US was limited for total inactivation of POD and PME, this treatment resulted to be advantageous in terms of time for blanching at mild temperatures. US probe treatments could also be considered as an advantageous alternative to low-temperature long-time (LTLT) conventional treatments for those applications in which partial inactivation of PME is required for the better preservation of carrot structure.     

Incorporation of theophylline in a chitosan/chondroitin sulfate hydrogel matrix: In vitro release studies and mechanical properties according to pH changes

Hydrogels based on natural polymers have been widely applied as vehicles for controlled drug release because of their advantages and interesting properties. In this study, a physical hydrogel based on chitosan and chondroitin sulfate (CS) was formed under mild conditions to act as a potential device for the controlled release of theophylline (TH). In vitro CS and TH release studies at pH 2 and 8 were performed. Under acid conditions (pH 2), the fraction of TH released (ca. 0.87) was higher than that of CS (ca. 0.13). On the other hand, under basic conditions, the fractions released of both substances were similar (ca. 0.57). In addition, the system presented in this work was able to sustain the TH release in a controlled way for 30 h. The variation of the pH affected the mechanical properties and contributed to form ordered regions within the hydrogel network, as observed through compression tests and wide‐angle X‐ray scattering analysis. The experimental data and discussion presented in this article will contribute to the development of a new vehicle for controlled TH release; this ensures the efficacy of the drug and reduced the number of daily doses administered. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Optimization of Supercritical CO2 Extraction of Fish Oil from Viscera of African Catfish (Clarias gariepinus)

Fish oil was extracted from the viscera of African Catfish using supercritical carbon dioxide (SC-CO₂). A Central Composite Design of Response Surface methodology (RSM) was employed to optimize the SC-CO₂ extraction parameters. The oil yield (Y) as response variable was executed against the four independent variables, namely pressure, temperature, flow rate and soaking time. The oil yield varied with the linear, quadratic and interaction of pressure, temperature, flow rate and soaking time. Optimum points were observed within the variables of temperature from 35 °C to 80 °C, pressure from 10 MPa to 40 MPa, flow rate from 1 mL/min to 3 mL/min and soaking time from 1 h to 4 h. However, the extraction parameters were found to be optimized at temperature 57.5 °C, pressure 40 MPa, flow rate 2.0 mL/min and soaking time 2.5 h. At this optimized condition, the highest oil yields were found to be 67.0% (g oil/100 g sample on dry basis) in the viscera of catfish which was reasonable to the yields of 78.0% extracted using the Soxhlet method.     

Supercritical CO2 and low-pressure solvent extraction of mango (Mangifera indica) leaves: Global yield,extraction kinetics,chemical composition and cost of manufacturing

Low-pressure solvent extraction (LPSE) and supercritical fluid extraction (SFE) were used to obtain extracts from mango (Mangifera indica) leaves. Kinetics curves were determined for both methodologies. The extracts chemical compositions and manufacturing costs were determined for both processes. Global yield isotherms for SFE process were determined at 10–40 MPa and 313–323 K. The highest yield was 2.24% at 30 MPa and 323 K; the LPSE yield (9.3%) was almost three times higher than that of SFE (3.6%). Thin layer chromatography showed that mango leaves extracts have several classes of compounds as alkaloids, flavonoids and terpenoids, recovered by both methods. The cost of manufacturing (COM) mango leaves extracts were US$ 32/kg and US$ 92/kg for LPSE and SFE, respectively.     

The effect of the conditions of electrodeposition on the capacitive properties of dinitrobenzoyl-derivative polypyrrole films

Films of poly[(R)-(−)-3-(1-pyrrolyl)propyl-N-(3,5-dinitrobenzoyl)-α-phenylglycinate] (polyDNBP) were deposited, using the galvanostatic method, onto indium tin oxide electrodes in the presence of the electrolytes tetrabutylammonium tetrafluoro-borate [(C₄H₉)₄NBF₄] or LiClO₄. Atomic force microscopy revealed that polyDNBP/(C₄H₉)₄NBF₄ films exhibited a grainy morphology with higher roughness and greater superficial area than polyDNBP/LiClO₄ films. Moreover, polyDNBP/(C₄H₉)₄NBF₄ films exhibited a higher capacitive electrochemical response when characterised in LiClO₄ rather than in (C₄H₉)₄NBF₄. Since polyDNBP films exhibit both n- and p-doping, they may have considerable potential application as electrodes in type III capacitor assemblies.