Microbiological quality of fruit juices sold in Tripoli–Libya

Fruit juices are becoming an important part of the modern diet in many communities. Data regarding the microbiological quality of foods, particularly fruit juices, sold in Libya and the neighboring North African countries are few if not lacking. Using standard microbiological procedures, 146 fruit juice samples sold in Tripoli were examined. Total bacterial counts (TBC) of samples examined ranged between <1 and 3 × 10⁵ CFU/ml (mean = 5 × 10⁴). Almond juice showed the highest TBC ranging between 1.8 × 10³ and 3 × 10⁵ (mean = 1.7 × 10⁵). Staphylococcus aureus was detected in 8 (5.5%) samples, Streptococcus spp. in 4 (2.7%), coliforms in 33 (22.6%), Escherichia coli (none were of serogroup O157) in 3 (2.1%), Klebsiella pneumonia in 17 (11.6%), Aeromonas spp. in 3 (2.1%), Pseudomonas aeruginosa in 6 (4.1%), Candida albicans in 18 (12.3%), Candida spp. in 109 (74.7%) and other yeasts in 85 (58.2%). Many of these organisms can cause disease in humans, which indicates that a large number of juices tested did not fulfill the Libyan guidelines for the microbiological quality of juices. Application of the HACCP system should be introduced into the food industry sector to improve the quality of fruit juices and other foods manufactured in Libya.     

CFD assessment of intake fraction in the indoor environment

In this paper we use a validated CFD model to calculate the inhalation exposure, expressed as an intake fraction (iF), of a seated person in an office with different contaminant sources, a floor diffuser, and a ceiling vent. These sources include the floor, the walls, a desk, and the human body. First, experimental data is used to determine the correct turbulent Schmidt number for the computational model to predict the transport of the species in an indoor environment. It was found at a turbulent Schmidt number of ∼0.9 produced the best fit when compared to experimental data. Then, the iF was calculated for two representations of the computer simulated person (CSP): a CSP with detailed surface geometry, and a simplified CSP with multi-block geometry. It was found that the simplified multi-block geometry is not adequate for predicting iF because it radically changes the flowfield of the thermal plume in the breathing zone (BZ). Next, the effect of personal ventilation systems on iF was investigated. The results show that such systems can reduce the iF by an order of magnitude compared with conventional mixing and displacement ventilation systems. Finally, a comparison of iF results were made for a surface body temperature of 32 °C and 28 °C. It was found that a 4 °C change in body surface temperature influenced the iF by less than 10%.     

Enhanced ionic conductivity in calcium doped ceria – Carbonate electrolyte: A composite effect

Recently, ceria-based nanocomposites, as a proton and oxygen ion conductor, has been developed as promising electrolyte candidates for low-temperature solid oxide fuel cells (LTSOFCs). Up to now, samarium doped ceria (SDC) was studied as a main oxide for nanocomposite electrolyte; while calcium doped ceria (CDC) is considered as a good alternative from both material performance and economical aspects. Yet the conduction behavior of CDC-based composite has not been reported. In the present study, calcium doped ceria was prepared by oxalate co-precipitation method, and used for the fabrication of CDC/Na₂CO₃ composite. The thermal decomposition process, structure and morphology of the samples were characterized by TGA, XRD, SEM, etc. The oxygen ion conductivity of single phase CDC sample was measured by electrochemical impedance spectroscopy (EIS), while the proton and oxygen ion conductivity of CDC/Na₂CO₃ nanocomposite sample were determined by four-probe d.c. measurements. The CDC/Na₂CO₃ samples show significantly enhanced overall ionic conductivity compared to that of single phase CDC samples, demonstrating pronounced composite effect. This confirms that the use of nanocomposite as electrolyte can effectively lower the operation temperature of SOFC due to improved ionic conductivity.     

Breakthrough Curves Analysis and Statistical Design of Phenol Adsorption on Activated Carbon

Activated carbon was used as an adsorbent for the removal of phenol from aqueous solution under various operating conditions. Statistical design using MATLAB® tools was employed to study the effects of three variables on six different response factors. MATLAB® software was employed to solve proposed quadratic model equations and for fitting a quadratic response surface. All the models with a very high adjusted R‐square predicted the experimental data well. The Thomas, the Yoon‐Nelson, the Wolborska, the bed depth service time, and the linear driving force models were used to predict breakthrough curves for experimental data. The results showed that the linear driving force model was suitable for the prediction of the breakthrough curve data.     

Stability of peroxidized oils and fat to high temperature heating

The fatty acid compositions of extracted and commercial samples of cottonseed oil, groundnut oil, sesame oil and butter fat were determined by gas-liquid chromatography. These fats were subjected to frying temperature (195 ºC) for 3 hours and the peroxide value, iodine value, free fatty acid content and the carbonyl value were determined at hourly intervals. The stability of the oils did not correlate well with the ratio of C18:2 to C81:1 nor with the degree of unsaturation. Also, it was not a function of the susceptibility of these oils and fat to hydrolyse during the heating process. The data suggest that the fatty acids, present in these oils and fat, influence each other's oxidation and thus affecting the rate of oxidation. It appears that one of the major predisposing factors in the degradation of these oils and fat is the amount of saturated fatty acids which are present in contact with unsaturated and peroxidised fatty acids. This explanation has been discussed in relation to the degree of unsaturation of the oils used in the experiments and their vitamin E contents.     

THERMODYNAMICS OF COBALT(II) EXTRACTION BYTHENOYLTRIFLOUROACETONE AND DIBENZO-18-CROWN-6 IN NITROBENZENE-TOLUENE MIXTURES

Cobalt (II) was extracted by thenoyltrifluoroacetone (HTTA) and its mixture with dibenzo-18-crown-6(Dbl8C6) at different temperatures in nitrobenzene (Nb); toluene (Tol) or their mixtures, from perchlorate aqueous media of constant ionic strength (o.l;H⁺,NaClO₄) buffered with acetic acid-sodium acetate solutions. Slop analysis of the experimental results indicated that the stoichiometry of the chelate and the adduct extracted are Co(TTA)₂and Co(TTA)₂?Dbl8C6, under all the experimental conditions investigated. The extraction constants of the chelate (k₂o)’ tne mixed species (k_2land the formation constant of the adduct ( B_2lwere evaluated for the different diluents used at the different temperatures. It was found that log k_2oand log_2lincrease by increasing the dielectric constant (€ ) of the diluent whereby log B_2ldecreases by increasing €. These results were expressed in terms of linear free energy relationships. From the effect of the temperature on the different constants evaluated; the thermodynamic constants of the systems were calculated and discussed in terms of the nonspecific effect of the diluents used and the dehydration of the extracted chelate to form the adduct.     

SYNERGIC EXTRACTION OF COBALT(II) BY STRUCTURALLY RELATED CROWN ETHERS AND THENOYLTRIFLUOROACETONE

ABSTRACT

Cobalt (II) was extracted from perchlorate aqueous media by thenoyltrifluoroacetone (HTTA)alone and mixed with 12-Crown-4 (12C4) 15-Crown-5 (15C5) 18-Crown-6 (18C6)dibenzo-18-Crown-6 (Dbl8C6)dicyclohexyl-18-Crown-6 (Dchl8C6) or dicyclohexyl-24-Crown-8 (Dch24C8), in chloroform. The extraction constant of the chelate (K20) the extraction constant of the mixed species (K21), the synergic factor (S.F.) and the formation constant of the extracted adducts (β₂₁) were evaluated. The adduct stoichiometry was found to have the general formula Co(TTA)₂CE, irrespective of the crown ether (CE) used. It was found that no specific cavity size is required for the adduct formation. The synergic values K₂₁, S.F., and β₂₁as related to the crown ether took the order Dch24C8 > 18C6 > Dchl8C6 > 15C5 > Dbl8C6 > 12C4, which could be explained in terms of the crown ether basicity rather than the correspondence between the cavity size of the crown ether and the cobalt(II) crystal radii. The sequence 18C6 > Dchl8C6 > Dbl8C6 was interpreted in terms of the withdrawing ability of Dch and Db as substitutes in reducing the basic character of the adjacent crown ether oxygen donors.     

Giant Polarization in Quasi-Adiabatic Ferroelectric Na+ Electrolyte for Solid-State Energy Harvesting and Storage

The advent of new solid-state energy storage devices to tackle the electrical revolution requires the usage of nonlinear behavior leading to emergent phenomena. The ferroelectric analyzed herein belongs to a family of electrolytes that allow energy harvesting and storage as part of its self-charging features when thermally activated. The Na_2.99Ba_0.005ClO electrolyte shows quasi-adiabatic behavior with a continuous increase in polarization upon cycling, displaying almost no hysteresis. The maximum polarization obtained at a weak electric field is giant and similar to the remanent polarization. It depends on the temperature with a pyroelectric coefficient of 5.37 C m⁻² °C⁻¹ from −5 to 46 °C. The emergence occurs via negative resistance and capacitance. The glass transition is found to have its origins in the sharp depolarization at 46 – 48 °C. Above –10 °C, at ≈ –5 °C, another thermal anomaly may rely on the topologic characteristics of the A_3–2xBa_xClO (A = Li, Na, K) glass electrolytes enabling positive feedback of the current of electrons throughout the surface of the inner cell. The phenomena may pave the way toward a better understanding of dipolar nanodomain fragile glasses with exceptional ferroelectric characteristics to architect energy harvesting and storage devices based on multivalent thermally activated Na⁺-ion-ion electrolytes.     

Harnessing Topology and Stereochemistry of Glycidylamine-Derived Lipid Nanoparticles for in Vivo mRNA Delivery to Immune Cells in Spleen and Their Application for Cancer Vaccination

mRNA lipid nanoparticles (LNPs) have reached an inflection point and are now paving the way for a new wave of precision therapies. The design of nonhepatocyte RNA delivery systems without targeting ligands, however, remains a challenge. It is reported that the development of ligand-free glycidylamine (GA) derivatives containing LNPs (GA-LNPs) that preferentially deliver mRNA to immune cells in the spleen. Notably, it is demonstrated that the stereochemistry of GA-lipids has a significant impact on their self-assembly and in vitro and in vivo RNA delivery efficiency and tropism. This impact is dependent on the monomeric structure of GA and number of stereogenic centers. Furthermore, the nonlinear topology of GA lipid derivatives induced a sevenfold improvement in mRNA delivery efficiency. The top-performing estriol-GA05-30 LNPs elicited strong antitumor activity in a therapeutic and prophylactic cancer model and are well tolerated in mice. These results highlight the significance of the chemistry of ionizable lipids for extrahepatic RNA delivery and indicated a promising direction for the development of next-generation mRNA immunotherapies.