Did you know that light can create sound? In the late 19th century, scientist Alexander Graham Bell (considered one of the inventors of the telephone) discovered the phenomenon of materials producing sound waves after absorbing light energy, known as the photoacoustic effect. Alexander Graham Bell Image Source: Sina Technology After the 1960s, with the development of weak signal detection technology, highly sensitive microphones and piezoelectric ceramic microphones appeared. Scientists developed a new spectroscopic analysis technique based on the photoacoustic effect - photoacoustic spectroscopy, which can be used to detect substances of samples and their spectroscopic thermal properties, becoming a powerful tool for physicochemical research in inorganic and organic compounds, semiconductors, metals, polymer materials, etc. How can we make light create sound?As shown in the figure below, a light source modulated by a monochromator, or a pulsed light such as a pulsed laser, is incident on a photoacoustic cell. The material to be measured in the photoacoustic cell absorbs light energy, and the absorption rate varies with the wavelength of the incident light and the material. This is due to the different energy levels of the atomic molecules constituted in the different materials, and the absorption rate of light by the material increases when the frequency ν of the incident light is close to the energy level hν. The atomic molecules that jump to higher energy levels after absorbing light do not remain at the higher energy levels; instead, they tend to release energy and relax back to the lowest ground state, where the released energy often appears as thermal energy and causes the material to expand thermally and change in volume.When we restrict the volume of a material, for example, by packing it into a photoacoustic cell, its expansion leads to changes in pressure. After applying a periodic modulation to the intensity of the incident light, the temperature, volume, and pressure of the material also change periodically, resulting in a detectable mechanical wave. This oscillation can be detected by a sensitive microphone or piezoelectric ceramic microphone, which is what we call a photoacoustic signal. Principle Schematic How does a lock-in amplifier measure photoacoustic signals? In summary, the photoacoustic signal is generated by a much smaller pressure signal converted from very small heat (released by atomic or molecular relaxation). The detection of such extremely weak signals necessarily cannot be done without lock-in amplifiers. In photoacoustic spectroscopy, the signal collected from the microphone needs to be amplified by a preamplifier and then locked to the frequency signal we need by a lock-in amplifier. In this way, a high signal-to-noise ratio photoacoustic spectroscopy signal can be detected and the properties of the sample can be measured. CIQTEK has launc...
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 MoreOn August 26, 2020, Quantum Artificial Intelligence for Science and Technology (QuArtist) of College of Science, Shanghai University started its first quantum computing experiment course based on the CIQTEK Diamond Quantum Computer for Education. QuArtist Center, Shanghai University QuArtist was officially inaugurated on May 31, 2019, and headed by Enrique Solano, an internationally renowned physicist, as its director. The QuArtist Center is dedicated to cutting-edge research on the fundamentals and applications of quantum computing and artificial intelligence, and will take the opportunity of the "quantum second revolution" in the 21st century to integrate quantum computing and artificial intelligence, and build a world-class center for quantum software and quantum hardware as its core goal. The QuArtist Center combines the three elements of high-end talent, hard work, and original innovation to contribute to the construction of science and innovation. After learning about CIQTEK Diamond Quantum Computer for Education, QuArtist Center immediately communicated with CIQTEK about the quantum education offerings. on August 26, CIQTEK application engineers were invited to QuArtis Center to open the first class of "Quantum computing experiment course". The principles and functions for basic quantum computing experiments were demonstrated on-site. After the lesson, Dean Chen from the College of Science of Shanghai University commented, "The class based on the CIQTEK Diamond Quantum Computer for Education makes the often obscure theoretical concepts such as decoherence, Rabi oscillations, and dynamic decoupling more vivid and easy to understand for students." Quantum Computing Experiment Course at QuArtist Center, Shanghai University In addition, Shanghai University will offer a quantum computing course based on CIQTEK Diamond Quantum Computer for Education to graduate students and undergraduates in the College of Science, and will start the preparatory work for the course after the new semester begins, including the selection of course content and course program design, etc. CIQTEK will also actively cooperate with Shanghai University to do a good job of course-related work, and provide customized services based on its course positioning. Based on Diamond Quantum Computer for Education, CIQTEK can provide customized services including laboratory construction, teaching handouts, teaching videos, teaching courseware, demonstration class training, and other overall supporting solutions related to quantum computing teaching, so that schools and teachers can open related experimental courses more easily. CIQTEK Application Engineers Show the Teaching Machine to Teachers and Students CIQTEK Diamond Quantum Computer for Education The Diamond Quantum Computer for Education is a teaching instrument based on the principle of NV-center and spin magnetic reso...
View MoreCeramic capacitors, as a kind of basic passive components, are an indispensable member of the modern electronic industry. Among them, chip multilayer ceramic capacitors (MLCC) occupy more than 90% of the ceramic capacitor market due to their characteristics of high temperature resistance, high voltage resistance, small size, and wide range of capacitance, and are widely used in the consumer electronics industry, including home appliances, communications, automotive electronics, new energy, industrial control, and other application areas. The use of CIQTEK SEM can assist in completing the failure analysis of MLCC, finding the origin of failure through micro-morphology, optimizing the production process, and achieving the goal of high product reliability. Application of CIQTEK SEM in MLCC MLCC consists of three parts: inner electrode, ceramic dielectric and end electrode. With the continuous updating of the market demand of electronic products, MLCC product technology also presents the development trend of high capacity, high frequency, high temperature and high voltage resistance, high reliability and miniaturization. Miniaturization means the need to use smaller-sized, more uniform ceramic powders. The microstructure of the material determines the final performance, and the use of scanning electron microscope to characterize the microstructure of ceramic powders, including particle morphology, particle size uniformity, and grain size, can help in the continuous improvement of the preparation process. Scanning electron microscope imaging of different types of barium titanate ceramic powders /25kV/ETD Scanning Electron Microscope Imaging Different types of barium titanate ceramic powders /1kV/Inlens High reliability means that a deeper understanding of the failure mechanism is required, and therefore failure analysis is indispensable. The root cause of MLCC failure is the presence of various microscopic defects, such as cracks, holes, delamination, etc., either externally or internally. These defects will directly affect the electrical performance and reliability of MLCC products, and bring serious hidden danger to product quality. The use of scanning electron microscope can assist in completing the failure analysis of capacitor products, find the origin of the failure through the microscopic morphology, optimize the production process, and ultimately achieve the goal of high reliability of the product. MLCC's internal is a multi-layer structure, each layer of ceramics whether there are defects, multi-layer ceramics thickness is uniform, whether the electrodes are covered uniformly, all of these will affect the life of the device. When using SEM to observe the internal multilayer structure of MLCC or to analyze their internal failures, it is often necessary to perform a series of pre-treatments on the samples before they can be tested. These include resin embedding, mechanical grinding, ...
View MoreDrug powders are the main body of most pharmaceutical formulations, and their efficacy depends not only on the type of drug, but also to a large extent on the properties of the powders composing the pharmaceutical formulations. Numerous studies have shown that physical parameters such as specific surface area, pore size distribution and true density of drug powders are related to the properties of powder particles such as particle size, hygroscopicity, solubility, dissolution and compaction, and play an important role in the purification, processing, mixing, production and packaging capabilities of pharmaceuticals. Especially for APIs and pharmaceutical excipients, parameters such as specific surface area are important indicators of their performance. The specific surface area of API, as the active ingredient of a drug, affects its properties such as solubility, particle size and solubility. Under certain conditions, the larger the specific surface area of the same weight of API, the smaller the particle size, dissolution and dissolution rate is also accelerated. By controlling the specific surface area of the API, it can also achieve a good uniformity and fluidity, to ensure uniform distribution of drug content. Pharmaceutical excipients, as excipients and additional agents used in the production of drugs and prescriptions, specific surface area is one of the important functional indicators, which is important for diluents, binders, disintegrants, flow aids, and especially lubricants. For example, for lubricants, the specific surface area significantly affects their lubrication effect, because the prerequisite for lubricants to play a lubricating effect is to be able to be uniformly dispersed on the surface of the particles; generally speaking, the smaller the particle size, the larger the specific surface area, and the easier it is to be uniformly distributed during the mixing process. Thus, accurate, rapid and effective testing of physical parameters such as specific surface area and true density of pharmaceutical powders has always been an indispensable and critical part of pharmaceutical research. Therefore, the methods for the determination of specific surface area and solid density of pharmaceutical powders are clearly defined in the United States Pharmacopoeia USP<846> and USP<699>, the European Pharmacopoeia Ph. Eur. 2.9.26 and Ph. Eur. 2.2.42, as well as in the second additions of the physical and chemical analysis contents 0991 and 0992 to the four general rules of the Chinese Pharmacopoeia, 2020 edition. 01 Gas adsorption technique and its application Gas adsorption technique is one of the important methods for material surface property characterization. Based on adsorption analysis, it can accurately analyze the specific surface area, pore volume and pore size distribution, true density and other parameters of APIs, pharmaceutical excipients and drug formulations. In turn, it can do some...
View MoreEnvironmental catalysts are broadly defined as all catalysts that can improve environmental pollution. In recent years, environmental protection has become more and more popular, and the research and application of environmental catalysts have become more and more in-depth. The environmental catalysts for processing different reactants have corresponding performance requirements, among which the specific surface area and pore size are one of the important indexes for characterizing the properties of environmental catalysts. It is of great significance to use gas adsorption technology to accurately characterize the physical parameters such as the specific surface area, the pore volume and the pore size distribution of the environmental catalysts for the research and optimization of their performance. 01Environmental protection catalyst Currently, oil refining, chemical and environmental protection industries are the main application fields of catalysts. Environmental catalysts generally refer to the catalysts used to protect and improve the surrounding environment by directly or indirectly treating toxic and hazardous substances, making them harmless or reducing them, broadly speaking, catalysts capable of improving environmental pollution can be attributed to the category of environmental catalysts. Environmental catalysts can be divided into exhaust gas treatment catalysts, wastewater treatment catalysts and other catalysts according to the direction of application, such as molecular sieve catalysts that can be used for the treatment of exhaust gases such as SO2, NOX, CO2, and N2O, activated carbon that can be used as a typical adsorbent for the adsorption of liquid/gas-phase pollutants, as well as semiconductor photocatalysts that can degrade organic pollutants, and so on. 02 Specific surface and pore size analysis and characterization of environmental catalysts Catalyst surface area is one of the important indexes to characterize catalyst properties. The surface area of catalyst can be divided into outer surface area and inner surface area. Since the majority of the surface area of environmental catalyst is inner surface area and the active center is often distributed on the inner surface, generally, the larger the specific surface area of environmental catalyst is, the more activation centers are on the surface, and the catalyst has a strong adsorption capacity for reactants, which are all favorable to the catalytic activity. In addition, the type of pore structure has a great influence on the activity, selectivity and strength of the catalyst. Before the reactant molecules are adsorbed, they must diffuse through the pores of the catalyst to reach the active center on the inner surface of the catalyst, and this diffusion process is closely related to the pore structure of the catalyst, and different pore structures show different diffusion laws and apparent reaction kinetics, for example, the strong selectivity of ...
View MorePaleomagnetism is an interdisciplinary discipline between geology, physics, and geophysics. Paleomagnetism generally studies the direction and strength of the Earth's magnetic field, planetary launch and its evolution pattern during geological periods by measuring the natural residual magnetization intensity of rocks or ancient artifacts. Rocks are a combination of natural minerals, and their residual magnetism generally comes from ferromagnetic minerals in rocks, containing primary and secondary remanent magnetism. The so-called primary remanent magnetism refers to the geomagnetic field information recorded when the rocks were formed. In contrast, the residual magnetism obtained after the formation of rocks is called secondary remanence, such as that obtained by rocks under the action of external magnetic fields (e.g., natural lightning strikes, erosion by running water and sand). Since paleomagnetism studies the characteristics of the geomagnetic field at the time of rock formation, accurate measurement of primary remanent magnetism becomes an important research tool. Currently, rock magnetism is analyzed by measuring the net magnetic moment of large samples of millimeter to centimeter size. Common instruments for scientific analysis include superconducting petrographs and vibrating sample magnetometers. However, at the submicron scale, geological samples are usually inhomogeneous in mineralogy and texture, with only a small fraction of ferromagnetic particles carrying residual magnetization. Therefore, characterizing rock magnetism in this context requires a technique that can image magnetic fields at the nanoscale of space and with high sensitivity. For example, scanning superconductivity microscopy (SQUID), magnetoresistive microscopy, and Hall microscopy, which are being widely used, are examples. (a) Quantum diamond microscopy at Harvard University (b) Measurement of residual magnetization in geological samples In 2011, researchers demonstrated that nitrogen-vacancy chromatic cores (NV chromatic cores for short) in diamond can be used for magnetic imaging on the submicron scale.In 2017, R.L. Walsworth et al. at Harvard University used a self-built quantum diamond microscope based on NV chromatic cores to achieve imaging of rock magnetic fields with a metric spatial resolution of 5 um and a field-of-view range of 4 mm.By By reducing the distance between the diamond and the sample (≤10 um), a magnetic moment sensitivity of 10-16 A-m2 was achieved, which is comparable to and even surpasses the mainstream equipment such as SQUID, magnetoresistive microscope, and Hall microscope. In addition, the quantum diamond microscope also has the advantage of optical imaging function and fast imaging speed. It can be seen that in the detection and analysis of geological and magnetic meteorites, quantum diamond microscopy shows great potential for application, opening up a new path for wea...
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