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Antibacterial Activity of Seaweeds and their Extracts
Published in Leonel Pereira, Therapeutic and Nutritional Uses of Algae, 2018
In the study developed by Devi et al. (2012), seaweed Sargassum swartzii (formerly Sargassum wightii) was screened for the potential bioactive natural substance against human bacterial pathogens. Crude extracts were made using three solvents (acetone, ethanol, and methanol) and then screened for antibacterial activity against human pathogens. The crude extracts were purified by silica gel column chromatography and five fractions obtained from each solvent were collected separately and tested for activity. The second fraction of purified ethanol extract showed maximum activity against seven human bacterial pathogens compared to other fractions of ethanol, methanol, and acetone. This was again subjected for purification by silica gel column chromatography and the three sub-fractions obtained were also tested for the activity. Of the three fractions, the third sub-fraction of ethanol extract showed the highest zone of inhibition against Escherichia coli (25.5 mm), followed by Staphylococcus aureus (22.85 mm), Salmonella paratyphi (19.1 mm), Salmonella typhi (18.5 mm), Pseudomonas aeruginosa (18.25 mm), Vibrio cholerae (17.5 mm), Klebsiella pneumoniae (16.15 mm), Shigellasonnie (15.2 mm), and the lowest zone of inhibition was observed against Proteus sp. (12 mm), and Klebsiella sp. (8.5 mm).
Rheological Additives
Published in Laba Dennis, Rheological Proper ties of Cosmetics and Toiletries, 2017
J. M. Huber Listed in decreasing order of thickening efficiency and oil absorption— Zeothix® 265.Zeosyl® 200.Zeodent® 163.Zeofree® 153.Silica Gel
History and Sources of Essential Oil Research
Published in K. Hüsnü Can Başer, Gerhard Buchbauer, Handbook of Essential Oils, 2020
A very simple and standardized fractionation in terms of speed and simplicity has been published by Kubeczka (1973) using dry-column chromatography. The procedure, which has been proved useful in numerous experiments for prefractionation of an essential oil, allows a preseparation into five fractions of increasing polarity. The preseparation of an essential oil into oxygenated constituents, monoterpene hydrocarbons, and sesquiterpene hydrocarbons, which is—depending on the oil composition—sometimes of higher practical use, can be performed successfully using reversed-phase RP-18 HPLC (Schwanbeck et al., 1982). The HPLC was operated on a semipreparative scale by stepwise elution with methanol–water 82.5:17.5 (solvent A) and pure methanol (solvent B). The elution order of the investigated oil was according to decreasing polarity of the components and within the group of hydrocarbons to increasing molecular weight. Fraction 1 contained all oxygenated mono- and sesquiterpenoids, fraction 2 the monoterpene hydrocarbons, and fraction 3—eluted with pure methanol—the sesquiterpene hydrocarbons. A further alternative to the mentioned separation techniques is flash chromatography, initially developed by Still et al. (1978), which has often been used as a rapid form of preparative LC based on a gas- or air pressure–driven short-column chromatography. This technique, optimized for rapid separation of quantities typically in the range of 0.5–2.0 g, uses dry-packed silica gel in an appropriate column. The separation of the sample generally takes only 5–10 min and can be performed with inexpensive laboratory equipment. However, impurities and active sites on dried silica gel were found to be responsible for isomerization of a number of oil constituents. After deactivation of the dried silica gel by adding 5% water, isomerization processes could be avoided (Scheffer et al., 1976). A different approach using HPLC on silica gel and isocratic elution with a ternary solvent system for the separation of essential oils has been published by Chamblee et al. (1985). In contrast to the aforementioned commonly used offline pretreatment of a sample, the coupling of two or more chromatographic systems in an online mode offers advantages of ease of automation and usually of a shorter analysis time.
Integrating inert dusts with other technologies in stored products protection
Published in Toxin Reviews, 2021
Masumeh Ziaee, Asgar Ebadollahi, Waqas Wakil
Kamel et al. (1965) found silica dust to be effective as a grain protectant in controlling postharvest insect pests. Silica gel indicated to protect paper flour sacks and shelf liners from Tribolium confusum Jacquelin du Val (Coleopteran: Tenebrionidae) and Oryzaephilus surinamensis (Linnaeus) (Coleoptera: Silvanidae) infestations, respectively. The residual toxicity of silica gel will persist 5 months showed long-term protection of sealed packages against stored-product insects (Watters 1966). Amorphos silica Cab-O-Sil in comparison with malathion, diazinon, and Kenite 2–1 DE, provided the most complete protection of wheat grains against Sitophilus oryzae (L.) (Coleoptera: Curculionidae), Rhyzopertha dominica F. (Coleoptera: Bostrichidae) and Cryptolestes pusillus (Schonherr) (Coleoptera: Cucujidae) for long-term period of 12 months (La Hue 1970). Another silica aerogel, Aerosil 380, provided acceptable control of T. confusum (Vrba et al. 1983). Gowers and Le Patourel (1984) applied a synthetic amorphous silica dust as slurry or dry powder as structural treatment on different surfaces including wheat grain, glass, vinyl, concrete and hessian sacking against Sitophilus granarius (L.) (Coleoptera: Curculionidae) within 96-h exposure period. They reported that the toxicity of the dry dust was the same as the aqueous suspension on glass, tile and concrete surfaces.
Evaluation of Pistia stratiotes fractions as effective larvicide against Anopheles mosquitoes
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2019
Jincai Ma, Yunusa Adamu Ugya, Asma’u Isiyaku, Xiuyi Hua, Tijjani Sabiu Imam
Isolation of pure compounds was performed by column chromatography of the extract on silica gel. Silica gel with 60–200 mesh size (product of Lobachemie Laboratory Reagents and Fine chemicals, Mumbai, India) was used as a stationary phase in the column. To prepare the column, a glass tube of 5.0-cm diameter and 87-cm length was clamped vertically. The lower end of the column was fitted with a stopper and plugged with cotton wool as a support. Slurry of silica gel was prepared in solvent used for separation (250 g silica gel in 500 ml chloroform). The slurry was added to the column gradually and with gentle tapping to avoid cracks. This process was continued till a uniform column of desired length was obtained. The crude extract (40.42 g) was mixed with 25 g of silica gel to obtain homogenous mixture. This mixture was poured into the column and different fractions were eluted with different solvents viz. chloroform, ethyl acetate and formic acid. The extracted fractions were collected separately and the solvent of the collected fractions was evaporated at room temperature [3,22–24].
Effective treatment for hypertrophic scar with dual-wave-length PDL and Nd:YAG in Chinese patients
Published in Journal of Cosmetic and Laser Therapy, 2019
Li Lin, Peng Guo, Xining Wang, Ran Huo, Qiang Li, Siyuan Yin, Yongqian Cao
Hypertrophic scars can be treated through various methods, such as silica gel treatment, drug injections, local pressure, micro-plasma radio frequency, laser treatment, and surgical scar revision. Each method is useful, as well as comes with its own limitations. Silica gel works slowly. Drug injections include steroid or 5-Fluorouracil (5-FU) injections that can be painful and may cause surrounding tissue’s atrophy and telangiectasia, so it cannot be accepted by all patients. 5-FU is used as an antineoplastic agent because of its antimetabolic function. It can also be used to treat keloids and hypertrophic scars by intralesional injections (3). Wang S. reported that FMRT could improve color, thickness, and vascularity of the burn scar, while having no significant effect on contracture, pain, or itching (4). Surgery is the most important method to relieve tension in scar contractures and improve contour abnormalities.