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History and Sources of Essential Oil Research
Published in K. Hüsnü Can Başer, Gerhard Buchbauer, Handbook of Essential Oils, 2020
A simple device for rapid extraction of volatiles from natural plant drugs and the direct transfer of these substances to the starting point of a thin-layer chromatographic plate has been described by Stahl (1969a) and in his subsequent publications. A small amount of the sample (ca. 100 mg) is introduced into a glass cartridge with a conical tip together with 100 mg silica gel, containing 20% of water, and heated rapidly in a heating block for a short time at a preset temperature. The tip of the glass tube projects ca. 1 mm from the furnace and points to the starting point of the thin-layer plate, which is positioned 1 mm in front of the tip. Before introducing the glass tube, it is sealed with a silicone rubber membrane. This simple technique has proven useful for many years in numerous investigations, especially in quality control, identification of plant drugs, and rapid screening of chemical races. In addition to the aforementioned micro-hydrodistillation with the so-called TAS procedure (T, thermomicro and transfer; A, application; S, substance), several further applications, for example, in structure elucidation of isolated natural compounds such as zinc dust distillation, sulfur and selenium dehydrogenation, and catalytic dehydrogenation with palladium, have been described in the microgram range (Stahl, 1976).
Plastic Bag Asphyxia
Published in Burkhard Madea, Asphyxiation, Suffocation,and Neck Pressure Deaths, 2020
Lisa B.E. Shields, John C. Hunsaker
In deaths from gaseous or volatile substances, the lung may yield evidence of toxic substances [52]. The main bronchus is tied off, and the hilum is divided and placed into a nylon bag. It should be sent to the laboratory for airway head space volatile analysis. A plastic bag is not recommended as it is permeable to volatile substances. Glass tubes with an aluminium foil-lined cap or a polytetrofluorethylene (Teflon) liner should be utilized to collect blood samples for volatile substances. Plastic tubes or vials with a rubber septum as a seal are not appropriate to collect blood samples as volatile substances may escape through the rubber.
Liposomes
Published in Danilo D. Lasic, LIPOSOMES in GENE DELIVERY, 2019
LMV dispersion is placed in test tubes which are either sonicated in a bath sonicator or by tip sonication. Normally, 5 to 10 min sonication above Tc suffices for the preparation of SUVs with radii below 50 nm. With some lipids, radii below 20 nm can be obtained while some diacyl cationic lipids (including DOIC and DOGS) can even form micelles. DODAB/neutral lipid liposomes cannot be sized below 130 nm. Bath sonication is preferred because temperature can be better controlled and the sonicator tip can shed titanium particles during direct sonication, which must be centrifuged away (typically 5 to 10 min on the bench top centrifuge suffices). Bath sonication requires small sample volumes, typically about 1 mL/tube. Thick glass tubes are less likely to break during sonication and an argon blanket to reduce lipid oxidation is recommended. This method is the most suitable for samples which did not swell well (some neutral lipids often remain sticking on the surface of hydration vessel) or are gelly. Obviously, in these cases lipids have to be weighed directly in the test tube in which sonication will be performed. Tip sonication, which dissipates more energy into the sample, can contain, depending on the tip and container size, from 1 to 5 mL of sample. Besides the lipid composition and concentration, the size of vesicles produced depends on temperature, sonication time and power, volume of samples, as well as tuning; i.e., by carefully adjusting the position of the tip (level of water and tube position in a bath sonication experiment), one can achieve much better energy dissipation.
A computational framework for investigating bacteria transport in microvasculature
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Peter Windes, Danesh K. Tafti, Bahareh Behkam
Figure 7 compares the data retrieved from the present model with existing experimental trends for hematocrit ratio and relative apparent viscosity in narrow glass tubes (Pries et al. 1992; Sugihara-Seki and Fu 2005). Narrow glass tubes are commonly used as in vitro analogs for human capillaries. Both the trends and magnitudes of the hematocrit ratio and apparent viscosity compare favorably to the experimental data. Uncertainty can be incurred in the experimental data from measurement challenges and procedural uncertainty. Likewise, uncertainty can be incurred in the present computational model from numerical error and uncertainty in the plasma layer thickness input. Due to the low Reynolds number flow and the refined mesh used, the numerical error is negligible compared to the uncertainty in the plasma layer thickness data used to generate Eq. (3). Nonetheless, the model is able to capture the characteristics of capillary hemodynamics and is deemed sufficiently accurate to be used for studying bacteria transport.
Effects of Hypericum scabrum L. essential oil on wound healing in streptozotocin-induced diabetic rats
Published in Cutaneous and Ocular Toxicology, 2022
Fatma Ibaokurgil, Betul Apaydin Yildirim, Serkan Yildirim
The H. scabrum L. plant used in the study was picked during the flowering season in the Erzurum Palandöken region and dried in the shade (Figure 1). A voucher specimen has been deposited in the Herbarium of Ataturk University (voucher No. ATA9306) in Erzurum, Turkey. The dried plants were pulverized in a mill, and the ground plants were isolated using Clevenger equipment and the hydrodistillation process. The essential oils were refined with Na2SO4 after being washed with chloroform (sodium sulfate). In a rotating evaporator, essential oils were extracted by eliminating chloroform at low pressure and temperature. The acquired essential oil's percent yield was calculated. It was kept in a sealed glass tube for use in the experiment16.
Correlation between vitamin D serum levels and severity of diabetic retinopathy in patients with type 2 diabetes mellitus
Published in Journal of Endocrinology, Metabolism and Diabetes of South Africa, 2021
Gauhar Nadri, Sandeep Saxena, Apjit Kaur, Kaleem Ahmad, Pragati Garg, Abbas Ali Mahdi, Levent Akduman, Katarina Gazdikova, Martin Caprnda, Pavol Vesely, Peter Kruzliak, Vladimir Krasnik
Blood samples were collected from study groups using a standard protocol. Fasting blood samples were drawn by vein puncture using a 5 ml metal-free plastic syringe fitted with a 24-gauge stainless steel needle under sterile conditions and blood samples were collected in a 4 ml vacutainer. The volume of the samples ranged from 7 ml to 8 ml. Blood was transferred into glass tubes for separation of serum. The tubes containing blood were set on to the stand and left for 30 minutes to allow the blood to clot. Subsequently, the samples were centrifuged at 1000× g for 10 minutes and serum was carefully removed to another tube. Haemoglobin, blood sugar fasting and post-prandial, glycated haemoglobin (HbA1c) and serum vitamin D were analysed. Haemoglobin A1c was measured using high-performance liquid chromatography.