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Maintaining the overall quality and shelf life of plant-based food and beverages is particularly important yet challenging to the food industry. Demand for natural preservation techniques has increased with the rising concerns over food safety and consumer awareness, e.g., health consciousness and food trends such as veganism and the demand for clean, labelled foods. Thus, a technique such as biopreservation has the potential to enhance food safety while fostering the quality, originality and naturalness of food. The application of probiotic microorganisms to foods and beverages provides various health benefits in addition to improved shelf life, stability and microbial safety of the food. The provision of probiotics is known to deliver various health benefits for the host’s gut health. Therefore, this review aims to investigate the importance of biopreservation and the role of probiotics in the food industry. An attempt was made to explore the various possibilities of shelf-life enhancement through the use of probiotic microorganisms as biopreservatives. Noticeable improvements in the shelf life of plant-based foods and beverages were observed due to the antimicrobial effects exerted by probiotics and potential probiotic strains which make them useful alternatives to artificially synthesized chemical preservatives.

Dye-sensitized solar cells were fabricated with a polyethylene oxide (PEO)-based quasi-solid (gel) electrolyte consisting of the ionic liquid 1-hexil-3-methylimidazoliym iodide (HMII), and tetrapropyl ammonium iodide (Pr4N+I−) as the two iodide salts with two dissimilar cations. Titanium dioxide powder (TiO2) (P-25) was added to the polymer electrolyte to enhance the iodide ion conductivity further by the nanofiller effect. The electrolyte and the solar cells were characterized by ionic conductivity and impedance measurements, DC polarization test, and current-voltage measurements. The maximum ionic conductivity of 6.95 × 10−3 S cm−1 at 30 °C was exhibited by the electrolyte composition with a 5 wt% TiO2 nanofiller concentration, and the activation energy of this electrolyte was 0.181 eV. The solar cell with this conductivity-optimized gel electrolyte had the highest short-circuit photocurrent of 8.72 mA cm−2 and the highest efficiency of 4.04% with an open-circuit voltage of 685.4 V and a fill factor of 67.6%. The addition of TiO2 nanofiller to the PEO-based gel polymer electrolyte has increased the electron recombination lifetime in the TiO2 photoanode from 2.23 ms for the TiO2 nanofiller-free electrolyte to 33.84 ms for the filler-added electrolyte. The enhancement of the solar cell efficiency is attributed to the mixed cation effect and the diffusion-mediated ionic conductivity increase due to the presence of the TiO2 nanofiller. [ABSTRACT FROM AUTHOR]

Temperature dependence of ionic conductivity of three different compositions of the Mg(BH4)2:polyethylene oxide (PEO):propylene carbonate (PC) polymer gel electrolyte with Mg(BH4)2:PEO molar ratios of 1:8, 1:10, and 1:12 was studied. The composition with Mg(BH4)2:PEO = 1:10 exhibited the highest ionic conductivity of 7.60 × 10−6 S cm−1 at 30 °C. The effect of TiO2 nanofiller on ionic conductivity enhancement was studied for Mg(BH4)2:PEO:PC:TiO2 polymer gel electrolyte by varying the TiO2 weight ratio from 0 to 12.5 wt.%. The highest ionic conductivity of 17.95 × 10−6 S cm−1 at 30 °C was exhibited by the electrolyte composition with 10 wt% of TiO2 nanofiller. The optimized electrolytes had a Mg++ cationic transference number of 0.22 for the filler free electrolyte and 0.30 for the TiO2 10wt% filler incorporated electrolyte. Both electrolytes had negligible electronic conductivity. A more than two-fold increase in the ionic conductivity and a 30% increase in Mg++ ion transference number can be attributed to the nanofiller effect caused by TiO2. This preliminary study shows the possibility of developing this PEO-based polymer gel electrolyte to be used in rechargeable Mg ion batteries. [ABSTRACT FROM AUTHOR]

Electrochromic devices based on nanofiber membrane gel electrolytes offer several advantages over polymer gel electrolytes. Many advantages, such as high chemical stability, easy handling, less leakage, a wide working temperature range, and a long cycle life, show high compatibility of nanofiber membrane electrolytes in different electrochemical power devices. In this work, we have succeeded in replacing the liquid electrolyte with a nanofiber membrane–based gel electrolyte prepared by the electrospinning method and applied in electrochromic devices (ECD). Polyacrilonitrile (PAN)–based nanofibers were deposited on a spin-coated SnO2 layer, prepared on a fluorine-doped tin oxide (FTO) glass substrate. The thickness of the fiber mat was varied by changing the time of the electrospinning. Gel-type membrane electrolyte was prepared by soaking the nanofiber membrane electrode in the 1 M LiClO4 in propylene corbonate (PC) solution. TiO2 electrochromic electrode was prepared by the "doctor blade" method. ECDs were fabricated with the configuration of FTO glass/TiO2/PAN-based nanofiber membrane gel polymer electrolyte/SnO2/FTO glass by sandwiching the two electrodes. Electrochromic performance of ECDs fabricated with nanofiber membrane gel electrolyte was compared with ECDs fabricated with liquid electrolyte (1 M LiClO4 in PC) and PAN-based conventional gel electrolyte (PC (0.4 g) + ethylene carbonate (EC) (0.4 g) + LiClO4 (0.03 g) + PAN). ECDs with nanofiber membrane gel electrolytes demonstrate a transmittance variation of 33.40% in the visible region which is 93% of the corresponding value obtained with liquid electrolyte–based ECD, whereas identical ECDs made with conventional gel electrolytes demonstrate a lower transmittance variation of 4.22%. [ABSTRACT FROM AUTHOR]

The effect of the thickness of a multilayer TiO2 photoanode on the performance of a dye-sensitized solar cell (DSC) made with a polyethylene oxide-based gel polymer electrolyte containing ternary iodides and performance enhancer 4-tert-butylpyridine is studied. Multilayer photoanodes consisting of up to seven layers of TiO2 nano-particles (13 nm and 21 nm) are prepared by spin coating of successive layers. XRD results confirm the predominant presence of the anatase phase of TiO2 in the multilayer structure after sintering. The SEM images reveal the formation of a single TiO2 film upon sintering due to merging of individually deposited layers. The photocurrent density (JSC) and the efficiency increase with the number of TiO2 layers exhibiting the maximum efficiency and JSC of 5.5% and 12.5 mA cm−2, respectively, for the 5-layered electrode of total thickness 4.0 µm with a 9.66 × 10–8 mol cm−2 surface dye concentration. The present study introduces a method of determining the rate of effective photoelectron generation and the average time gap between two successive photon absorptions where the respective results are 1.34 molecule−1 s−1 and 0.74 s for the most efficient cell studied in this work. [ABSTRACT FROM AUTHOR]

This study is about investigating the effect of adding TiO2-coated silver nanowires into a tri-layered photoanode of dye-sensitized solar cells (DSSCs) to improve the photovoltaic performance. Face-centred cubic silver nanowires (AgNWs) were synthesized via a rapid, scalable and green pathway method. The average length and diameter of AgNWs were 5 μm and 70 nm, respectively. AgNWs were coated with titanium dioxide (TiO2) using 2-mercaptoethanol as the binder. AgNW@TiO2 core-shell structure was formed by the hydrothermal method and the average diameter of the coated TiO2 was observed to be 14 nm. TiO2 shell showed anatase phase, which was a significant advantage for higher dye absorbance leading to a higher power conversion efficiency (PCE). The PCE for a DSSC with single-layered TiO2 photoanode increased from 6.70 to 8.87% due to AgNW@TiO2 core-shell structured photoanode, reflecting a 32.3% enhancement. The PCE for a DSSC with tri-layered AgNWs@TiO2 core-shell structured photoanode was 10.5% showing an impressive enhancement of 49.6% compared to the DSSC with a pure tri-layered TiO2 photoanode. TiO2 shell appears to act as a protective shell around AgNWs by both resisting redox chemical corrosion of Ag by iodide ions in the electrolyte and increasing the thermal stability of AgNWs against annealing at high temperatures. Further, TiO2-coated AgNWs facilitate increased photoelectron generation by plasmonic effect, reduce the recombination and enhance the electron lifetime while providing a direct pathway for excited electrons leading to a significant improvement in the PCE of DSSC. [ABSTRACT FROM AUTHOR]