The name coral comes from the Old Persian sanga (stone), which is the common name for the coral worm community and their skeleton. Coral polyps are corals of the phylum Acanthozoa, with cylindrical bodies, which are also called living rocks because of their porosity and branching growth, which can be inhabited by many microorganisms and fish. Corals flourish in tropical ocean. The chemical composition of white coral is mainly CaCO3 and contains organic matter, called carbonate type. Golden, blue, and black coral is composed of keratin, called keratin type. Red coral (including pink, flesh red, rose red, light red to deep red) shell has more keratin and CaCO3. Cora, based on the skeletal structure characteristics, can be divided into plate bed coral, four-shot coral, six-shot coral, and eight-shot coral. Modern coral is mostly the latter two categories. Coral is an important carrier to record the marine environment, for the determination of paleoclimatology, ancient sea level change and tectonic movement and other studies have important significance. Electron paramagnetic resonance spectroscopy is a powerful tool for studying substances with unpaired electrons. This technique utilizes microwave irradiation to probe the energy separation of unpaired electrons created by an external magnetic field. A special application of EPR spectroscopy is developed for analyzing corals, which is a valuable method marine environmental studies. The information regarding paleoclimate is reflected in the Mn2+ concentration in coral reef. Using EPR spectroscopy, the signal of Mn2+ can be easily analyzed and interpreted, since its concentration is relatively high during a warm period and decreases sharply during a period of rapid cooling. Another set of substances in coral that can be measured by EPR spectroscopy is lattice defects and impurities produced by natural irradiation. Such lattice defects trap unpaired electrons, which produces observable EPR signals. The lineshape of such signals are indicative to the composition of minerals and trapped impurities, and therefore can be used for inferring the information about age of formation as well as crystallization condition of samples. The EPR signal in the coral will be analyzed using a CIQTEK X-Band EPR (ESR) spectroscopy EPR100 to provide information on the composition and defect vacancies in the coral. CIQTEK X-Band EPR100 Experimental Sample The sample was taken from white coral in the South China Sea, treated with 0.1 mol/L dilute hydrochloric acid, crushed with a mortar, sieved, dried at 60°C, weighed about 70 mg, and tested on the CIQTEK EPR100. White Coral Sample Electron Paramagnetic Resonance Spectroscopy The CIQTEK EPR100 was used to test the EPR signal in white coral. To achieve accurate measurement of the EPR signal, the specific experimental conditions were as follows. Experimental Conditions ...
View MoreTo begin with, what is aged rice and new rice? Aged rice or old rice is nothing but stocked rice that is kept for aging for one or more years. On the other hand, new rice is the one which is produced from newly harvested crops. Compared to the fresh aroma of new rice, aged rice is light and tasteless, which is essentially a change in the internal microscopic morphological structure of aged rice. Researchers analyzed new rice and aged rice using the CIQTEK tungsten filament scanning electron microscope SEM3100. Let's see how they differ in the microscopic world! CIQTEK Tungsten Filament Scanning Electron Microscope SEM3100 Figure 1 Cross-sectional fracture morphology of new rice and aged rice First, the microstructure of rice endosperm was observed by SEM3100. From Figure 1, it can be seen that the endosperm cells of new rice were long polygonal prismatic cells with starch grains wrapped in them, and the endosperm cells were arranged in a radial fan shape with the center of the endosperm as concentric circles, and the endosperm cells in the center were smaller compared with the outer cells. The radial fan-shaped endosperm structure of new rice was more obvious than that of aged rice. Figure 2 Microstructure morphology of the central endosperm of new rice and aged rice Further magnified observation of the central endosperm tissue of rice revealed that the endosperm cells in the central part of aged rice were more broken and the starch granules were more exposed, making the endosperm cells radially arranged in a blurred form. Figure 3 Microstructure morphology of protein film on the surface of new rice and aged rice The protein film on the surface of the endosperm cells was observed at high magnification using the advantages of SEM3100 with high-resolution imaging. As can be seen from Figure 3, a protein film could be observed on the surface of new rice, while the protein film on the surface of aged rice was broken and had different degrees of warping, resulting in relatively clear exposure of the internal starch granule shape due to the reduction of the surface protein film thickness. Figure 4 Microstructure of endosperm starch granules of new rice Rice endosperm cells contain single and compound amyloplasts. Single-grain amyloplasts are crystalline polyhedra, often in the form of single grains with blunt angles and obvious gaps with the surrounding amyloplasts, containing mainly crystalline and amorphous regions formed by straight-chain and branched-chain amylose [1,2]. The complex grain amyloplasts are angular in shape, densely arranged, and tightly bound to the surrounding amyloplasts. Studies have shown that the starch grains of high-quality rice exist mainly as complex grains [3]. By observing the endosperm cells of new rice, as shown in Figure 4, the starch grains mostly existed in the form of compound grains. The compound starch grains were angular in shape and closely...
View MoreHave you ever noticed that commonly used pills or vitamin tablets have a thin coating on their surface? This is an additive made from magnesium stearate, which is usually added to medicines as a lubricant. So why is this substance added to medicines? What is Magnesium Stearate? Magnesium Stearate is a widely used pharmaceutical excipient. It is a mixture of magnesium stearate (C36H70MgO4) and magnesium palmitate (C32H62MgO4) as the main ingredients, which is a fine white non-sanding powder with a slippery sensation when in contact with the skin. Magnesium stearate is one of the most commonly used lubricants in pharmaceutical production, with good anti-adhesive, flow-increasing, and lubricating properties. The addition of magnesium stearate in the production of pharmaceutical tablets can effectively reduce the friction between the tablets and the die of the tablet press, greatly reducing the tablet force of the pharmaceutical tablet press and improving the consistency and quality control of the drug. Magnesium Stearate Image from the Internet The key property of magnesium stearate as a lubricant is its specific surface area, the larger the specific surface area, the more polar it is, the greater the adhesion, and the easier it is to distribute evenly on the particle surface during the mixing process, the better the lubricity. CIQTEK self-developed static volume method-specific surface and pore size analyzer V-Sorb X800 series can be used to test the gas adsorption of magnesium stearate and other materials, and analyze the material's BET surface area. The instrument is easy to operate, accurate, and highly automated. Effect of Specific Surface Area on Magnesium Stearate Studies have pointed out that the physical properties of the lubricant can also have a significant impact on the pharmaceutical product, such as the lubricant surface condition, particle size, size of surface area, and structure of the crystals. Through grinding, drying, and storage magnesium stearate can change its original physical properties, thus affecting its lubricating function. Good magnesium stearate has a low shear lamellar structure [1] and can be properly mixed with the active component of the drug and other excipients to provide lubrication between the compacted powder and the mould wall and to prevent adhesion between the powder and the mould. The larger the specific surface area of magnesium stearate, the easier it is to distribute it evenly over the surface of the particles during the mixing process, and the better the lubrication. Under certain conditions of the mixture and the tablet press, the larger the specific surface area of magnesium stearate the lower the tensile strength of the tablets obtained, the higher the brittleness, and the slower the dissolution and disintegration. Therefore, the surface area is considered an important technical index of pharmaceutical-grade magnesium stearate. The specific sur...
View MoreIn scientific research, pollen has a wide range of applications. According to Dr. Limi Mao, Nanjing Institute of Geology and Paleontology, Chinese Academy of Sciences, by extracting and analyzing different pollen deposited in the soil, it is possible to understand which parent plants they came from respectively, and thus infer the environment and climate at that time. In the field of botanical research, pollen mainly provides microscopic reference evidence for systematic taxonomy. More interestingly, pollen evidence can also be applied in criminal investigation cases. Forensic palynology can effectively corroborate the facts of a crime by using pollen spectrum evidence on the suspect's accompanying clothing and at the crime scene. In the field of geological research, pollen has been widely used in reconstructing vegetation history, past ecology, and climate change studies. In archaeological studies exploring early human farming civilizations and habitats, pollen can help scientists understand the history of early human domestication of plants, what food crops were cultivated, etc. Fig. 1 3D pollen model picture (taken by Dr. Limi Mao, product developed by Dr. Oliver Wilson) The size of pollen varies from a few microns to more than two hundred microns, which is beyond the resolution of visual observation and requires the use of a microscope for observation and study. Pollen comes in a wide variety of morphologies, including variations in size, shape, wall structure, and ornamentation. The ornamentation of pollen is one of the key bases for identifying and distinguishing pollen. However, the resolution of the optical biological microscope has physical limitations, it is difficult to precisely observe the differences between different pollen ornamentation, and even the ornamentation of some small pollen cannot be observed. Therefore, scientists need to use a scanning electron microscope (SEM) with high resolution and large depth of field to obtain a clear picture of pollen morphological features. In the study of fossil pollen, it is possible to identify the specific plants to which the pollen belongs, so as to more accurately understand the vegetation, environment, and climate information of the time. The Microstructure of Pollen Recently, researchers have used the CIQTEK Tungsten Filament SEM3100 and the CIQTEK Field Emission SEM5000 to microscopically observe a variety of pollen. Fig. 2 CIQTEK Tungsten Filament SEM3100 and Field Emission SEM5000 1. Cherry blossom Pollen grains spherical-oblong. With three pore grooves (without treated pollen, the pores are not obvious), the grooves reach both poles. Outer wall with striate ornamentation. 2. Chinese violet cress (Orychophragmus violaceus) Chinese violet cress pollen morphology is ellipsoidal, with 3 grooves, the surface has a reticulated pattern, and the mesh size varies. 3. Ottelia Pollen grains are rounded, wit...
View MoreDrug powder is the main body of most drug formulations, and its efficacy depends not only on the type of drug, but also to a large extent on the properties of the powder that makes up the agent, including particle size, shape, surface properties and other kinds of parameters. The specific surface area and pore size structure of drug powders are related to the properties of powder particles such as particle size, hygroscopicity, solubility, dissolution and compaction, which play an important role in the purification, processing, mixing, production and packaging capabilities of pharmaceuticals. In addition, the validity, dissolution rate, bioavailability and efficacy of drugs also depend on the specific surface area of the material. Generally speaking, the larger the specific surface area of pharmaceutical powders within a certain range, the faster the dissolution and dissolution rate will be correspondingly accelerated, which ensures the uniform distribution of drug content; however, too large a specific surface area will lead to the adsorption of more water, which is not conducive to the preservation and stability of drug efficacy. Therefore, accurate, rapid and effective testing of the specific surface area of pharmaceutical powders has always been an indispensable and critical part of pharmaceutical research. Case Study of CIQTEK Application in Pharmaceutical Powder We combines the actual characterization cases of different drug powder materials to clearly show the methods and applicability of this technology to characterize the physical properties of different drug surfaces, and then make some basic analysis on the expiration date, dissolution rate and efficacy of drugs, and help the pharmaceutical industry to develop with high quality. The V-Sorb X800 series specific surface and pore size analyzer is a high throughput, fast and economical instrument, which can realize rapid testing of specific surface area of incoming and outgoing finished products, pore size distribution analysis, quality control, adjustment of process parameters, and prediction of drug performance, etc. Automatic BET Surface Area & Porosimetry Analyzer CIQTEK EASY-V Series CIQTEK SEMs 1、Scanning electron microscope and specific surface and pore size analyzer in montmorillonite dispersion Montmorillonite is obtained from the purification and processing of bentonite, which has unique advantages in pharmacology because of its special crystal structure with good adsorption capacity, cation exchange capacity and water absorption and swelling capacity. For example: as API, drug synthesis, pharmaceutical excipients, etc. Montmorillonite has a laminar structure and a large specific surface area, which can have a strong adsorption effect on toxic substances; it is electrostatically combined with digestive tract mucus proteins and plays a protective and repairing role on the digestive tract mucosa. ...
View MoreSpin trapping electron paramagnetic resonance (EPR) method is a method that combines the spin-trapping technique with the EPR technique to detect short-lived free radicals. Why Use Spin Trapping Technology?Free radicals are atoms or groups with unpaired electrons formed by the covalent bonding of compound molecules under external conditions such as heat and light. They are widely found in nature.With the development of interdisciplinary disciplines such as biology, chemistry, and medicine, scientists have found that many diseases are associated with free radicals. However, due to their active and reactive nature, the free radicals generated in the reactions are often unstable at room temperature and difficult to be detected directly using conventional EPR spectroscopy methods. Although short-lived free radicals can be studied by time-resolved EPR techniques or low-temperature fast-freezing techniques, their lower concentrations for most free radicals in biological systems limit the implementation of the above techniques. The spin trapping technique, on the other hand, allows the detection of short-lived free radicals at room temperature through an indirect method. Fundamentals of Spin Trapping Technology In a spin-trapping experiment, a spin trap (an unsaturated antimagnetic substance capable of trapping free radicals) is added to the system. After adding the spin trap, the unstable radicals and the trap will form more stable or longer-lived spin adducts. By detecting the EPR spectra of the spin adducts and processing and analyzing the data, we can invert the type of radicals and thus indirectly detect the unstable free radicals. Figure 1 Principle of spin capture technique (DMPO as an example) Selection of Spin Trap The most widely used spin traps are mainly nitrone or nitroso compounds, typical spin traps are MNP (2-methyl-2-nitrosopropane dimer), PBN (N-tert-butyl α-phenyl nitrone), DMPO (5,5-dimethyl-1-pyrroline-N-oxide), and the structures are shown in Figure 2. And an excellent spin trap needs to satisfy three conditions. 1. Spin adducts formed by spin traps with unstable free radicals should be stable in nature and long-lived. 2. The EPR spectra of spin adducts formed by spin traps and various unstable radicals should be easily distinguishable and identifiable. 3. Spin trap is easy to react specifically with a variety of free radicals, and there is no side reaction. Based on the above conditions, the spin trap widely used in various industries is DMPO. Figure 2 Schematic chemical structure of MNP, PBN, DMPO Table 1 Comparison of common spin traps Common Types of Spin-trapping Free Radicals In spin trapping experiments, the most common ones are O- and N-centered radicals, such as reactive oxygen species (ROS) and reactive nitrogen species (RNS), but not all ROS and RNS are free radical...
View MoreSpin trapping technique has been widely used in biology and chemistry because it can achieve the detection of short-lived radicals. For spin trapping experiments, many factors such as the time of trapping agent addition, trapping agent concentration, system solvent and system pH can affect the experimental results. Therefore, for different radicals, it is necessary to select the trapping agent and design the experimental scheme reasonably to achieve the best experimental results. 1.Trapping Agent and Solvent Selection The common O-center radicals are hydroxyl radicals, superoxide anion radicals, and singlet oxygen. Hydroxyl radicals (∙OH) For hydroxyl radicals, they are usually detected in aqueous solutions and captured using DMPO, which forms adducts with DMPO with half-lives of minutes to tens of minutes. Superoxide anion radicals (∙O2-) For superoxide anion radicals, if DMPO is chosen as the trapping agent, the detection needs to be performed in a methanol system. This is because the binding ability of water and DMPO is higher than that of superoxide radicals to DMPO. If superoxide radicals are detected in water, the binding speed of water to DMPO will be greater than that of superoxide radicals to DMPO, resulting in superoxide radicals not being easily captured. Of course, if the superoxide radicals are produced in large amounts, they may also be captured by DMPO. If one wants to trap superoxide radicals in aqueous solution, BMPO needs to be chosen as the trapping agent because the half-life of adducts formed by BMPO trapping superoxide radicals in aqueous solution can be up to several minutes. Single-linear state (1O2) For single-linear state oxygen detection, TEMP is usually selected as the capture agent, and its detection principle is shown in Figure 1. Single-linear state oxygen can oxidize TEMP to form TEMPO radicals containing single electrons, which can be detected by electron paramagnetic resonance spectrometry. Since TEMP is easily oxidized and prone to background signal, TEMP needs to be tested before detecting single-linear state oxygen as a control experiment. Figure 1 Mechanism of TEMP for detecting singlet oxygen Table 1 Common O-center radical detection trapping agent and solvent selection 2、Addition Time of Trapping Agent In photocatalytic reactions, when light irradiates the catalyst, the valence band electrons are excited to the conduction band, producing electron/hole pairs. Such experiments generally require the addition of the trapping agent before the light irradiation, and in combination with the in situ light system, the variation of the radical signal with the light irradiation time can be studied, as shown in Figure 2, with different light irradiation times, the ∙OH content generated varies. Fig. 2 Results of CIQTEK in-situ illumination experiments In the warming reaction, if the reaction temperature...
View MoreSince the 1950s, when Watson and Crick proposed the classical double helix structure of DNA, DNA has been at the heart of life science research. The number of the four bases in DNA and their order of arrangement lead to the diversity of genes, and their spatial structure affects gene expression.In addition to the traditional DNA double helix structure, studies have identified a special four-stranded DNA structure in human cells, the G-quadruplex, a high-level structure formed by the folding of DNA or RNA rich in tandem repeats of guanine (G), which is particularly high in rapidly dividing G-quadruplexes are particularly abundant in rapidly dividing cells (e.g., cancer cells). Therefore, G-quadruplexes can be used as drug targets in anticancer research. The study of the structure of the G-quadruplex and its binding mode to binding agents is important for the diagnosis and treatment of cancer cells. Schematic representation of the three-dimensional structure of the G-quadruplex.Image source: Wikipedia Electron-Electron Double Resonance (DEER) The Pulsed Dipolar EPR (PDEPR) method has been developed as a reliable and versatile tool for structure determination in structural and chemical biology, providing distance information at the nanoscale by PDEPR techniques. In G-quadruplex structure studies, the DEER technique combined with site-directed spin labeling (SDSL) can distinguish G-quadruplex dimers of different lengths and reveal the binding pattern of G-quadruplex binding agents to the dimer.Differentiation of G-quadruplex Dimers of Different Lengths Using DEER TechnologyUsing Cu(pyridine)4 as a spin label for distance measurement, the tetragonal planar Cu(pyridine)4 complex was covalently bound to the G-quadruplex and the distance between two paramagnetic Cu2+ in the π-stacked G quaternary monomer was measured by detecting dipole-dipole interactions to study the dimer formation.[Cu2+@A4] (TTLGGG) and [Cu2+@B4] (TLGGGG) are two oligonucleotides with different sequences, where L denotes the ligand. The DEER results of [Cu2+@A4]2 and [Cu2+@B4]2 are shown in Figure 1 and Figure 2. From the DEER results, it can be obtained that in [Cu2+@A4]2 dimers, the average distance of single Cu2+ -Cu2+ is dA=2.55 nm, the G-quadruplex 3′ end forms G-quadruplex dimer by tail-tail stacking, and the gz-axis of two Cu2+ spin labels in G-quadruplex dimer is aligned parallel.The [Cu2+@A4]2 π stacking distance is longer (dB-dA = 0.66 nm) compared to the [Cu2+@A4]2 dimers. It was confirmed that each [Cu2+@B4] monomer contains an additional G tetramer, a result that is in full agreement with the expected distances. Thus, distance measurements by the DEER technique can distinguish G-quadruplex dimers of different lengths. Fig. 1 (A) The pulsed EPR differential spectrum (black line) of [Cu2+@A4]2 dimer and its corresponding simulation (red line) (34 GHz, 19 K); (B) After background correction, four phases in a-d DEER time-domain ...
View More