Optimization of Bioactive Phenolics Extraction and Cosmeceutical Activity of Eco-Friendly Polypropylene-Glycol–Lactic-Acid-Based Extracts of Olive Leaf

Olive leaf is a rich source of phenolic compounds with numerous activities related to skin health and appearance. In this study, a green extraction method was developed using eco-friendly solvents: polypropylene glycol (PPG), lactic acid (LA), and water. The optimal extraction conditions were established, including solvent, extraction time, technique (magnetic stirrer vs. ultrasound-assisted extraction), and herbal material/solvent ratio. The composition of the solvent mixture was optimized using a mixture design. The content of phenolic compounds, including oleuropein and verbascoside, was determined using high-performance liquid chromatography (HPLC) and spectrophotometric methods. Using different extraction conditions, three extracts were prepared and their phytochemical compositions and antioxidant and skin-related bioactivities were investigated. The extracts were excellent inhibitors of elastase, collagenase, tyrosinase, and lipoxygenase. The best activity was shown by the extract richest in phenolics and prepared using magnetic-stirrer-assisted extraction for 20 min, with 0.8 g of herbal material extracted in 10 mL of PPG/LA/water mixture (28.6/63.6/7.8, w/w/w), closely followed by the extract prepared using the same extraction conditions but with 0.42 g of herbal material. The investigated PPG/LA/water mixtures contributed to the overall enzyme-inhibitory activity of the extracts. The prepared extracts were appropriate for direct use in cosmetic products, thus saving the time and energy consumption necessary for the evaporation of conventional solvents.

Impacts of various mixing approaches towards black seed oil-alginate emulsion attributes

Black seed oil (BSO) contains thymoquinone, an active ingredient that is well-known for its antioxidant property. The bitter taste of BSO makes it challenging for the consumers, mainly children and the elderly, to consume it every day. Thus, BSO is encapsulated in alginate beads in micrometre size to enhance its palatability. This encapsulation was previously established in the lab-scale and the standard mixing method to produce a stable BSO-alginate emulsion used a magnetic stirrer coupled with a sonicator. This mixing method is not suitable for the production of BSO beads at a large scale. Hence, this research aims to investigate the impacts of various mixing methods coupled with sonication towards the BSO-alginate emulsion attributes. Four BSOalginate coarse emulsions were prepared using a magnetic stirrer (MS) as the benchmark, overhead stirrer (OS), homogeniser (H), and overhead stirrer combined with homogeniser (OSH). All the coarse emulsions were then sonicated to produce a nanoemulsion using a flow cell sonicator. The coarse emulsions were characterised in terms of dissolution time while the nanoemulsions were characterised in terms of droplet size, polydispersity index, zeta potential, conductivity and absorbance. These characteristics were statistically compared to the benchmark emulsion characteristics. MS, OS, H, and OSH coarse emulsion formation required 45, 230, 102, and 46 minutes to be produced, respectively. There were significant differences (p <0.05) between the droplet size of OSH (266.53±4.36) nm and MS (285.50±1.15) nm emulsions, indicating that the OSH emulsion was more stable. The absorbance of OSH BSO-alginate nanoemulsion was significantly lower (p <0.05) than the benchmark. In comparison to MS as the benchmark, OSH technique produced a stable emulsion in terms of lower dissolution time, droplet size, zeta potential, and absorbance.

Process and Energy Intensification of Glycerol Carbonate Production from Glycerol and Dimethyl Carbonate in the Presence of Eggshell-Derived CaO Heterogeneous Catalyst

The process and energy intensifications for the synthesis of glycerol carbonate (GC) from glycerol and dimethyl carbonate (DMC) using an eggshell-derived CaO heterogeneous catalyst were investigated. The transesterification reaction between glycerol and DMC was typically limited by mass transfer because of the immiscible nature of the reactants. By varying the stirring speed, it was observed that the mass transfer limitation could be neglected at 800 rpm. The presence of the CaO solid catalyst made the mass transport-limited reaction process more prominent. Mass transfer intensification using a simple kitchen countertop blender as an alternative to overcome the external mass transfer limitation of a typical magnetic stirrer was demonstrated. A lower amount of the catalyst and a shorter reaction time were required to achieve 93% glycerol conversion or 91% GC yield, and the turnover frequency (TOF) increased almost 5 times from 1.5 to 7.2 min−1 when using a conventional magnetic stirrer and countertop blender, respectively. In addition, using a simple kitchen countertop blender with 7200 rpm, the reaction temperature of 60 °C could be reached within approximately 3 min without the need of a heating unit. This was the result of the self-frictional heat generated by the high-shear blender. This was considered to be heat transfer intensification, as heat was generated locally (in situ), offering a higher homogeneity distribution. Meanwhile, the trend toward energy intensification was promising as the yield efficiency increased from 0.064 to 2.391 g/kJ. A comparison among other process intensification techniques, e.g., microwave reactor, ultrasonic reactor, and reactive distillation was also rationalized.

The Effect of Temperature on the Electrical Characteristics of Nanofluids Based on Palm Oil

This study sought to apply nanotechnology to develop the electrical characteristics of palm oil. Experiments were conducted using three types of nanoparticles: zinc oxide (ZnO), titanium dioxide (TiO2), and barium titanate (BaTiO3). The nanofluid samples were prepared by mixing the nanoparticles with palm oil using various processes. In the first scenario, a combination of palm oil with nanoparticles at 0.01 vol% was created, while the next sample had 0.03 vol% of nanoparticles. The samples were then fully dispersed using a magnetic stirrer, followed by ultrasonic dispersal in order to ensure homogeneity of the nanofluid. The electrodes were set 2.5 mm apart and the test was performed six times on each test sample in compliance with the IEC 60156 standard. The voltage breakdown characteristics were recorded for each of the liquids at temperatures varying from 35 °C to 90 °C. The results showed that for the palm oil samples containing nanoparticles, the voltage breakdown was greater than for the samples containing unmodified palm oil.

The Effect of Cellulose Nanocrystal Suspension Treatment on Suspension Viscosity and Casted Film Property

Cellulose nanocrystals (CNCs) have attracted significant interest in different industrial sectors. Many applications have been developed and more are being explored. Pre-treatment of the suspension plays a critical role for different applications. In this study, different pre-treatment methods, including homogenization, ultrasonication, and mixing with a magnetic stirrer were applied to a CNC suspension. After treatment, the rheological behaviors of the treated CNC suspensions were characterized using a rotational viscometer. The treated suspensions were then used to cast films for characterization by ultraviolet-visible (UV-Vis) and Fourier transform near-infrared spectroscopy (FT-NIR). All the CNC suspensions demonstrated a shear thinning phenomena. Homogenization or ultrasonication significantly decreased the suspension viscosity compared with the suspension mixed by a magnetic stirrer. The viscosity of CNC suspension changed with time after treatment and settlement of treated CNC suspensions in room conditions increased the viscosity dramatically with time. Different UV and visible light interferences were observed for the CNC films generated from suspensions treated by different methods. The degree of crystallinity of the CNC films evaluated by FT-NIR showed that the film from suspension treated by homogenization and ultrasonication has the highest degree of crystallinity. Pre-treatments of CNC suspension affected the suspension viscosities and formed film properties.

Response Surface Methodology to Optimize the Isolation of Dominant Volatile Compounds from Monofloral Greek Thyme Honey Using SPME-GC-MS

This study aimed at an experimental design of response surface methodology (RSM) in the optimization of the dominant volatile fraction of Greek thyme honey using solid-phase microextraction (SPME) and analyzed by gas chromatography-mass spectrometry (GC-MS). For this purpose, a multiple response optimization was employed using desirability functions, which demand a search for optimal conditions for a set of responses simultaneously. A test set of eighty thyme honey samples were analyzed under the optimum conditions for validation of the proposed model. The optimized combination of isolation conditions was the temperature (60 °C), equilibration time (15 min), extraction time (30 min), magnetic stirrer speed (700 rpm), sample volume (6 mL), water: honey ratio (1:3 v/w) with total desirability over 0.50. It was found that the magnetic stirrer speed, which has not been evaluated before, had a positive effect, especially in combination with other factors. The above-developed methodology proved to be effective in the optimization of isolation of specific volatile compounds from a difficult matrix, like honey. This study could be a good basis for the development of novel RSM for other monofloral honey samples.

A Facile and Efficient Bromination of Multi-Walled Carbon Nanotubes

The bromination of multi-walled carbon nanotubes (MWCNT) was performed with vapor bromine in a closed vessel, and they were subjected to intensive stirring with a magnetic stirrer for up to 14 days. The efficiency of bromination was compared depending upon duration. The structure and surface of the crude and purified products were characterized by detailed physicochemical analyses, such as SEM/EDS, TEM, XRD, TGA, Raman, and XPS spectroscopies. The studies confirmed the presence of bromine covalently bound with nanotubes as well as the formation of inclusion MWCNT–Br2 complexes. It was confirmed that Br2 molecules are absorbed on the surface of nanotubes (forming the CNT-Br2 complex), while they can dissociate close to dangling bonds at CNT defect sites with the formation of covalent C−Br bonds. Thus, any covalent attachment of bromine to the graphitic surface achieved around room temperature is likely related to the defects in the MWCNTs. The best results, i.e., the highest amount of attached Br2, were obtained for brominated nanotubes brominated for 10 days, with the content of covalently bound bromine being 0.68 at% (by XPS).

Hotplace Magnetic Stirrer Automatic Heat Control and Water Velocity Based on PID (Proportional Integral Derivative)

Hotplate magnetic stirrer is a laboratory tool that is used to heat or warm as well as mix or homogenize chemical solutions. This tool is available in chemical, microbiology and pharmaceutical laboratories. Equipped with a stirrer made of magnets (stir bar) which is used to homogenize chemical solutions. This magnetic stirrer hotplate uses an ATMega 16 microcontroller based system. It uses an infrared temperature sensor MLX90614 to measure and monitor the temperature of the solution, starting from the start of mixing which is assisted by rotating a DC motor as a stirring device until the liquid is mixed or homogeneous. Homogeneous conditions are indicated by the ADC value ( Analog to Digital Convertion) which is obtained constant. If you use the automatic menu, only choose the mixing solution on the automatic menu. There are four choices for the solution speed of 400-1600 rpm with an increase of 400, there are four temperature choices, namely 30-60 degrees Celsius in increments of 10, there is a choice of time used for stirring time at 1-30 minutes. For temperature display, stirring speed and stirring time can be seen on the LCD 20x4 display.

FORMULATION AND ANTIOXIDANT ACTIVITY OF NANO GEL ETHANOL EXTRACT OF KEPOK BANANA PEEL (MUSA X PARADISIACA L.)

Kepok banana peel (Musa x paradisiaca L.) contains flavonoids that act as antioxidants. The antioxidant activity of the ethanol extract of Kepok banana peel can be used as an active ingredient of nano gel. Nano-sized preparations can increase the efficiency of the delivery of active ingredients with lesser side effects and also decrease the stratum corneum to make it easier to penetrate. The objectives of this study were to determine whether the ethanol extract of Kepok banana peel (Musa x paradisiaca L.) can be formulated as nano gel and to measure its antioxidant activity. The method of nano gel preparation was stirring technique by using a magnetic stirrer and a sonicator. The antioxidant activity was measured using DPPH method. The results showed that the ethanol extract of kepok banana peel could be formulated as nano gel with size F0 = 161.9 nm; F1 = 171.3 nm; F2 = 165.6 nm; F3 = 163.9 nm which fulfilled the nano gel size requirement (20-200 nm) and the potential zeta value F0 = -43.4 mV; F1 = -43.7 mV; F2 = -46.9 mV; F3 = -47.0 mV fulfilled the requirements (smaller than -30 mV and greater than +30 mV). The antioxidant activity showed that the IC50 of ethanol extract of was stronger than IC50 of 1% nano gel (198.0279 µg/ml : 282.8933 µg/ml).