Effects of Dilute Acid Pretreatment on Chemical and Physical Properties of Kenaf Biomass

In the current research, kenaf represents an agricultural biomass that possesses enormous potential for industrial applications. Because of its complex structure, which is composed of cellulose, hemicellulose, and lignin, pretreatment process was conducted. Here, dilute acid pretreatment process was conducted, statistically using the response surface method, which included three parameters: mass of biomass (g), temperature (°C), and time (min). About 2 g of kenaf biomass was treated with 2% dilute sulphuric acid, and it was found to have higher glucose conversion (25.3%) when the process was conducted for 60 min at the temperature of 180°C. The main aim of the current research is to investigate the chemical and physical changes of kenaf biomass before and after the pretreatment. The changes could be clearly seen in the cellulose, hemicellulose, and lignin composition before and after the pretreatment, which were evaluated via TAPPI standard test methods. Morphological observation under scanning electron microscope confirmed the changes that took place on the kenaf biomass from complex to simple surface structure. Fourier transform infrared analysis confirmed the presence of cellulose, hemicellulose, and lignin contents of the kenaf biomass before and after pretreatment. Crystallinity of the treated kenaf biomass also increased from 46.6% to 70.0%, as evidenced from X-ray diffractometer analysis.     

Stability of Silica‐ and Enzyme‐Treated Palm Oil Under Deep Frying Conditions

The oxidative and thermal stability of low diglycerides palm oil produced via silica treatment (sPO) and enzymatic treatment (ePO) compared with standard quality palm oil (SQ) and premium quality palm oil (PQ) was investigated. Both of the oils displayed better oxidative stability compared with SQ as well as significantly higher (P < 0.05) thermal resistance and oxidative strength than SQ and PQ due to lower amounts of partial glycerides. Although the initial induction periods (IPs) of sPO and ePO were significantly lower compared with SQ and PQ, both the oils showed slower drops in their IP values. The darkening effect after frying was significantly (P < 0.05) slower in sPO compared with SQ, PQ, and ePO. Besides, there is no difference p > 0.05 in the rate of FFA formation between sPO and PQ. The anisidine value and peroxide values were lowest in sPO, followed by ePO, PQ, and SQ.     

LNT: A logical neighbor tree secure group communication scheme for wireless sensor networks

Secure group communication is a paradigm that primarily designates one-to-many communication security. The proposed works relevant to secure group communication have predominantly considered the whole network as being a single group managed by a central powerful node capable of supporting heavy communication, computation and storage cost. However, a typical Wireless Sensor Network (WSN) may contain several groups, and each one is maintained by a sensor node (the group controller) with constrained resources. Moreover, the previously proposed schemes require a multicast routing support to deliver the rekeying messages. Nevertheless, multicast routing can incur heavy storage and communication overheads in the case of a wireless sensor network. Due to these two major limitations, we have reckoned it necessary to propose a new secure group communication with a lightweight rekeying process. Our proposal overcomes the two limitations mentioned above, and can be applied to a homogeneous WSN with resource-constrained nodes with no need for a multicast routing support. Actually, the analysis and simulation results have clearly demonstrated that our scheme outperforms the previous well-known solutions.     

Comparison of analytical techniques for dynamic trace metal speciation in natural freshwaters

Several techniques for speciation analysis of Cu, Zn, Cd, Pb, and Ni are used in freshwater systems and compared with respect to their performance and to the metal species detected. The analytical techniques comprise the following: (i) diffusion gradients in thin-film gels (DGT); (ii) gel integrated microelectrodes combined to voltammetric in situ profiling system (GIME-VIP); (iii) stripping chronopotentiometry (SCP); (iv) flow-through and hollow fiber permeation liquid membranes (FTPLM and HFPLM); (v) Donnan membrane technique (DMT); (vi) competitive ligand-exchange/stripping voltammetry (CLE-SV). All methods could be used both under hardwater and under softwater conditions, although in some cases problems with detection limits were encountered at the low total concentrations. The detected Cu, Cd, and Pb concentrations decreased in the order DGT > or = GIME-VIP > or = FTPLM > or = HFPLM approximately = DMT (>CLE-SV for Cd), detected Zn decreased as DGT > or = GIME-VIP and Ni as DGT > DMT, in agreement with the known dynamic features of these techniques. Techniques involving in situ measurements (GIME-VIP) or in situ exposure (DGT, DMT, and HFPLM) appear to be appropriate in avoiding artifacts which may occur during sampling and sample handling.     

Soluble axially substituted phthalocyanines: Synthesis and nonlinear optical response

This review lays special stress on describing the synthesis of soluble axially substituted or bridged indium, gallium and titanium phthalocyanine complexes and their electronic absorption characteristics, photophysical and nonlinear optical properties. The enhanced solubility of the axially substituted or bridged phthalocyanine monomers and dimers, compared to the chloro analogues, shows that the usual tendency of phthalocyanines to form aggregates can be effectively suppressed by axial substitution. Axial substitution in phthalocyanine complexes has provoked relevant changes on the electronic structure of the molecule by altering the π-electronic distribution due to the dipole moment of the central metal-axial ligand bond. The nanosecond nonlinear absorption and the optical limiting of indium, gallium and titanium phthalocyanines seem to be dominated by a strong triplet state absorption in the optical region comprised between the Q- and B-bands in their UV/Vis absorption spectra. Graphical Abstract A series of highly soluble axially substituted and bridged phthalocyanine and naphthalocyanine complexes have been synthesized. Axial substitution in phthalocyanine complexes has provoked relevant changes on the electronic structure of the molecule by altering the π-electronic distribution due to the dipole moment of the central metal-axial ligand bond.     

Treatment of fresh produce with a Salmonella-targeted bacteriophage cocktail is compatible with chlorine or peracetic acid and more consistently preserves the microbial community on produce

Diets rich in minimally processed foods are associated with numerous health benefits, in part, due to their diverse, natural microbiota. However, antimicrobials, such as chlorine and peracetic acid (PAA), that are used to address food safety concerns may damage the natural microflora of fresh produce. One promising approach for targeting pathogenic bacteria in foods without impacting the normal food microbiota are bacteriophages. In this study, we observed that combinational treatment of conventional antimicrobials (PAA and chlorine) and bacteriophages, specifically the Salmonella-targeted preparation SalmoFresh, retained the bactericidal effectiveness of individual interventions, and in some cases, achieved substantially increased efficacy. Additionally, the bacterial microbiomes of farm fresh and organic produce were less affected after phage treatment compared to PAA and chlorine. Finally, our study revealed that resistance rates against SalmoFresh were relatively minor and unaffected by the stresses introduced after chemical washes and/or bacteriophage treatment.