50 results about "Raman scattering spectra" patented technology

The invention discloses a hybrid Ag / MXene / Fe-Co MOF surface enhanced Raman scattering sensor and an application of the hybrid Ag / MXene / Fe-Co MOF surface enhanced Raman scattering sensor in rapid detection of bacteria. According to the sensor, silver nanoparticles are prepared through a sodium citrate reduction method, a two-dimensional material MXene and a bimetal organic framework are combined, and a surface enhanced Raman scattering spectrum detection platform with high sensitivity, stability and anti-interference performance is constructed. The conductive network of MXene and the local surface plasmon resonance effect of silver nanoparticles synergistically enhance an electromagnetic field, and the porous structure of Fe-Co MOF enriches target molecules and forms dense hot spots, so that the Raman signal intensity is remarkably improved. Experiments show that the detection limit of the sensor to 4-mercaptobenzoic acid is as low as 10 <-12 > M, and the signal stability can last for 7 days; the detection limit on common pathogenic bacteria such as escherichia coli and staphylococcus aureus reaches 10 CFU / mL, and the linear correlation coefficient is superior to 0.96. The sensor has hydrophobicity and biocompatibility, can efficiently capture bacteria through capillary force, is suitable for trace detection of complex samples, and provides a new strategy for rapid diagnosis of clinical drug-resistant bacteria.

The invention relates to an in-situ detection device and method for gas dissolved in oil. Comprising a degassing module and a detection module, and the degassing module is in direct contact with transformer oil and used for separating dissolved gas in the transformer oil in a membrane degassing mode to obtain separated gas; the detection module comprises a distributed feedback laser, a coupler, a photoacoustic cell, a plurality of photoelectric detectors, an AD conversion module and an FPGA core control and demodulation system; the method comprises the following steps: introducing separated gas, exciting the separated gas in a photoacoustic cell by multiple beams of laser to generate a photoacoustic or optical signal, receiving the signal, demodulating the signal after AD conversion to obtain Raman scattering spectrum data, and analyzing the Raman scattering spectrum data to obtain the concentration of each component gas in the separated gas. And judging the internal fault type of the transformer according to the concentration of each component gas. The device can be in direct contact with transformer oil for gas separation detection, and interference possibly brought by a traditional detection method in the oil sample extraction and analysis process is avoided.

The application discloses a kind of covalent organic framework aerogel and its preparation method and application, belong to aerogel material technical field.The preparation method of the application is by graphite phase carbon nitride / graphene oxide heterojunction with 1,3,5-triformylphloroglucinol, 2,5-diaminobenzenesulfonic acid, sodium hydroxide is hydrothermal reaction, and join gold source and be modified, to prepare covalent organic framework aerogel.The covalent organic framework aerogel prepared in the application has the advantages of strong adsorption and self-cleaning capacity, and based on surface-enhanced Raman scattering spectrum (SERS) technology can be directly used as substrate to detect pollutants, and the concentration of pollutants can be evaluated.

The invention relates to the technical field of spectroscopy and molecular recognition, in particular to an SERS (Surface Enhanced Raman Scattering)-based technology. The invention provides an SERS (Surface Enhanced Raman Scattering) substrate for detecting various biomass molecules, which is characterized in that a chain polymer is used as a soft template, and a metal monatomic head-to-head local self-assembly structure is formed on the surface of a carrier. The structure not only promotes mutual proximity between metal single atoms, but also physically blocks aggregation of the metal atoms to the cluster structure in a manner of passivating the surface of the carrier. Charge redistribution between adjacent metal single atoms regulates and controls the electronic state of the surface of the whole semiconductor substrate, and then efficient photoinduced charge transfer is induced, so that low-frequency Raman signals of biomass molecules are amplified.

The present invention proposes a single-exposure hyperspectral imaging system based on intensity-polarization combined modulation mask and its detection method, comprising an excitation light source group, a compression acquisition module, a reconstruction module, and a polarization noise reduction module. The excitation light source group generates linearly polarized light to illuminate the object under test, causing it to produce photoluminescence or Raman scattering. The compression acquisition module receives the signal and completes the compression acquisition. The reconstruction module uses a deep learning algorithm to reconstruct the full polarization spectrum image data from the compressed observation image. The polarization noise reduction module removes the mirror reflection noise component and outputs the noise-reduced photoluminescence or Raman scattering hyperspectral image data. The present invention can quickly and stably complete photoluminescence and Raman scattering spectral imaging, improve material detection efficiency and signal-to-noise ratio, and is suitable for fields such as semiconductor detection.

The invention relates to the technical field of medicinal liquor component detection, and discloses an accurate detection system for medicinal liquor components. The system comprises a multi-source spectrum acquisition module, a dynamic component modeling module, a multi-mode difference fusion module, an abnormal component positioning module and a detection strategy optimization module. The multi-source spectrum acquisition module synchronously captures near-infrared absorption spectrum, Raman scattering spectrum and liquid chromatogram-mass spectrum combined data, and generates a standardized spectrum data matrix through adaptive filtering; the dynamic component modeling module constructs a feature extraction network based on a historical spectrum library, and outputs a theoretical component vector containing a target active component concentration interval; the multi-mode difference fusion module generates a multi-dimensional difference tensor through multi-mode difference analysis; the abnormal component positioning module generates an abnormal component distribution probability thermodynamic diagram in combination with the medicinal material association topology network; and the detection strategy optimization module dynamically configures detection parameters according to the thermodynamic diagram. According to the system, accurate detection and abnormal positioning of medicinal liquor components are realized, and the comprehensiveness and intelligent level of detection are improved.

The present invention relates to the field of spectroscopy and molecular recognition technology, and more specifically to a method based on SERS (surface enhanced Raman scattering spectroscopy) technology. The present invention provides a SERS substrate for detecting a variety of biomass molecules, using a chain polymer as a soft template to form a "head-to-head" localized self-assembly structure of metal single atoms on the carrier surface. This structure not only promotes the mutual proximity of metal single atoms, but also physically blocks the aggregation of metal atoms into cluster structures by passivating the carrier surface. The charge redistribution between neighboring metal single atoms regulates the electronic state of the entire semiconductor substrate surface, thereby inducing efficient photoinduced charge transfer, thereby amplifying the low-frequency Raman signal of the biomass molecules.

The invention discloses a photovoltaic cell, a photovoltaic module and a processing method of the photovoltaic cell, the surface of the photovoltaic cell is provided with an antireflection layer, and the antireflection layer has a saturated bond; when the anti-reflection layer on the surface of the photovoltaic cell is characterized by adopting a Raman scattering spectrum analysis test, a Raman spectrum chart obtained by the anti-reflection layer has a characteristic peak A, and the ratio range of the peak intensity of the characteristic peak A to the half-peak width is 1-25. According to the photovoltaic cell, a Raman spectrum chart in the antireflection layer has a characteristic peak A at the position, the ratio range of peak intensity to half-peak width is 1-25, the characteristic peak A is relatively sharp, intermolecular acting force in a molecular structure of the characteristic peak A is high, chemical bonds are not prone to breakage, and therefore the characteristic peak A at the position is the characteristic peak corresponding to a saturated bond; therefore, a large number of saturated bonds exist in the antireflection layer, and only a small number of unsaturated bonds or dangling bonds exist in the antireflection layer, so that the stability and passivation effect of the antireflection layer are ensured, and the photovoltaic cell is further ensured to have relatively good power generation efficiency.

This invention provides a method for detecting malachite green veterinary drug residues using SERS based on silver-coated gold nanorods. The method includes: mixing a malachite green standard solution with silver-coated gold nanorods, adding a coagulant to form a mixed solution, and performing Raman spectroscopy to obtain the surface-enhanced Raman scattering (SERS) peaks of the malachite green standard solution; determining the characteristic peaks used to identify malachite green using SERS by assigning the malachite green molecular structure to the Raman peak positions; and determining the linear relationship between the concentration of malachite green and the intensity of the characteristic peaks. The method also involves mixing the sample solution to be tested with silver-coated gold nanorods, adding a coagulant to form a mixed solution, and performing Raman spectroscopy to obtain the peak intensity of the characteristic peaks of malachite green in the sample solution. The concentration of malachite green in the sample solution is calculated based on the linear relationship between the concentration of malachite green and the peak intensity of the characteristic peaks. This invention enables accurate and rapid detection of malachite green in aquatic products, ensuring the safe production of aquatic products.

The invention pertains to the technical fields of bioanalytics and agriculture, and relates to a method and to an assembly for in-ovo sexing of bird eggs. The aim of the present invention is to provide a method and an assembly by means of which in-ovo sexing of bird eggs is achieved with a stable predictive accuracy of the sex and which are simple and cost-effective. The aim is achieved using a method and an assembly in which a fertilised bird egg incubated for 3 to 9 days is irradiated with at least two light-emitting laser beam sources with different excitation waves after the shell is opened, the captured and processed fluorescence scattering spectra and Raman scattering spectra being used, as complementary spectra associated with the different excitation wavelengths, to determine a classification value, and the sex being determined by comparing the determined classification value with an intrinsically determined threshold value. The method and the assembly can be used for sexing farm poultry.

The application discloses an in-situ Raman spectrum testing method and system in a plasma environment. The in-situ Raman spectrum testing system comprises a Raman testing device and a material growth equipment for growing a sample in the plasma environment. The Raman testing device is used for emitting a pulsed light signal to the material growth equipment and irradiating the sample grown on the material growth equipment, exciting the sample to generate a pulsed Raman scattering signal, and collecting the pulsed Raman scattering signal in a pulsed time domain, and obtaining a Raman scattering spectrum through data processing. The in-situ Raman spectrum testing system disclosed by the application reduces the interference of stray light in the plasma environment on the Raman spectrum testing by emitting a pulsed light signal by the Raman testing device and receiving a pulsed time domain Raman scattering signal excited by the pulsed light signal.

The present invention provides a method for detecting DNA methylation, comprising reacting a DNA of a gene with a metal cluster modified with a molecule having a function for binding DNA, amplifying signals of methylated bases in the DNA by surface-enhanced Raman scattering (SERS) spectroscopy, and detecting the DNA methylation based on the SERS spectrum.

This application discloses a sample detection system and method, applied in the field of spectral analysis technology. The system includes a light projection module, a sample carrier, a signal acquisition module, and a sample detection module. The light projection module emits a laser signal of the target wavelength and focuses it onto the sample to be tested on the sample carrier. The signal acquisition module uses a front-facing light-receiving probe and at least one side-facing light-receiving probe to acquire Raman scattering and Rayleigh scattering signals generated by the sample to be tested. The sample detection module performs spectral composition analysis on the acquired scattered light signals from the sample to obtain the Raman scattering spectrum, and detects the sample based on the Raman scattering spectrum. This application overcomes the drawback of weak signal intensity in related technologies, effectively improving Raman signal intensity, especially for rough samples, enabling efficient and accurate detection.

The invention discloses a multi-mode pathogen identification method, device, equipment and medium, and relates to the technical field of microfluidics, the method comprises the following steps: obtaining pathogen sample data corresponding to each outlet in a plurality of outlets of a microfluidic chip; the pathogen sample data comprises Raman scattering spectrum information and outlet distribution information; the Raman scattering spectrum information is obtained by performing surface enhanced Raman spectrum processing on pathogen group data, and the pathogen group data is output after mixing a sample to be detected and Raman scattering enhanced particles in the micro-fluidic chip and performing physical separation based on particle size difference; the particle sizes of the pathogen population data output by the outlets are different; and inputting pathogen sample data into the trained multi-modal deep learning model to obtain a pathogen type prediction result. According to the invention, the identification accuracy of pathogen types in mixed samples or complex environments is improved.

The application discloses a kind of water tower wall condensate water quality detection method and system, it is related to industrial water quality detection technical field, including obtaining target water tower real-time running environment data set, calculating the temperature gradient of each monitoring area in inner wall, combining humidity to predict condensate water active condensation region, in the region arrangement micro water quality sampling array timing collection water sample, after physical pretreatment, through multichannel parallel spectrum analysis device synchronous acquisition ultraviolet absorption, near infrared transmission and Raman scattering spectrum data, to multidimensional spectrum data fusion analysis and extract feature, generate multidimensional water quality feature vector, construct space water quality image.This method can match condensate water actual generation area sampling, through multispectral fusion analysis complete characterization water quality information, realize the accurate detection of water tower wall condensate water quality and space distribution image construction.

To provide a positive electrode material for a manganese-based sodium ion battery having advantages of high capacity and low cost, and a method for manufacturing the same.SOLUTION: The chemical formula of the positive electrode material is NaxM1aFebMncO2, 0.6 ≤ x ≤ 1.0, 0.05 ≤ a ≤ 0.4, 0.1 ≤ b ≤ 0.45, 0.4 ≤ c ≤ 0.6, a + b + c = 1, where M1 is a metallic element that is in a solid state and has no oxidation reduction function, and is preferably at least one of Li, Mg, Zn, Ca, and Al. In the XRD spectrum of the cathode material, the peak intensity ratio of the crystal plane diffraction peaks (003) and (104) is 0.5 ≤ I (003) / I (104) ≤ 0.98. In the Raman spectrum of the positive electrode material, the characteristic peak S appears in the range of 660 to 680cm - 1, the characteristic peak B appears in the range of 565 to 580cm - 1, and the peak intensity ratio of the two is 0.2 ≤ IS / IB ≤ 0.8.SELECTED DRAWING: Figure 6

The invention relates to the technical field of food quality detection, in particular to a green tea variety and producing area identification method based on multi-solvent fusion surface enhanced Raman spectroscopy, which comprises the following steps: crushing and sieving a green tea sample, adding ultrapure water, absolute ethyl alcohol or hydrochloric acid solution, oscillating and extracting, centrifuging, and reserving supernate; mixing the supernate with the silver nanoparticle suspension, performing ultrasonic treatment, dripping on a silicon wafer, drying, acquiring spectrums at three positions by adopting a laser confocal microscopic Raman spectrometer, and performing baseline correction to obtain an average spectrum, thereby obtaining a surface enhanced Raman scattering spectrum; carrying out data fusion on the surface enhanced Raman scattering spectrum through matrix splicing, CARS, PCA, t-SNE and UMAP; according to the method, the fusion spectrum is divided into a training set and a test set, an identification model is constructed by adopting SVM, KNN and RF, green tea variety classification and origin traceability are realized, spectrum data are processed from the aspects of complete information retention, feature screening, linear dimensionality reduction, local structure retention and multi-scale structure retention, and the classification accuracy reaches 98.21%.

A characteristic information extraction method of a small-molecule volatile substance, including: dividing a surface-enhanced Raman scattering (SERS) spectrum of the small-molecule volatile substance to obtain n wavelength subintervals, where n is a positive integer; sampling the n wavelength subintervals through weighted bootstrap sampling (WBS) to obtain W wavelength subintervals, where W is a positive integer less than n; and screening the W wavelength subintervals to obtain desired wavelength subintervals. This application also provides a rapid detection method and a portable detection system of a small-molecule volatile substance.

A method and system for functionalizing substrates for use in near field surface-enhanced Raman scattering (SERS) spectroscopy. Each functionalized glass substrate of a set of glass substrates functionalized with trimethoxy-[3-(methylamino)propyl] silane is coated with a colloidal solution of gold nanoparticles. A Raman-active dye is applied to the glass substrate through spin coating. A near field SERS spectroscopy of each functionalized glass substrate is performed. Hotspots that produce high-intensity scattering from the dyed immobilized gold nanoparticles are identified for each functionalized glass substrate. A direction of interparticle axis between two adjacent dyed immobilized gold nanoparticles and electromagnetic near field intensity of the scattering along the direction of the interparticle axis for each hotspot are identified for each functionalized glass substrate. A location of each interstitial position, the direction of the interparticle axis, and the electromagnetic near field intensity of the respective hotspot are mapped for each functionalized glass substrate.

The invention discloses a blood gas analysis method and a related device. The method comprises the following steps: acquiring a target Raman scattering spectrum of mixed gas exhaled by a human body; determining the pressure intensity of each single-component gas contained in the mixed gas exhaled by the human body according to the target Raman scattering spectrum and a plurality of pre-stored Raman intensity-pressure intensity corresponding relations; for each group of single-component gas, determining the concentration of the group of single-component gas based on the total pressure intensity of the mixed gas exhaled by the human body and the pressure intensity of the single-component gas; and determining a blood gas analysis result of the human body based on the concentration of each single-component gas contained in the mixed gas exhaled by the human body. As different single-component gases have different Raman scattering characteristic peaks, the types of the single-component gases included in the mixed gas can be determined after the first scattering spectrum is obtained; and the concentration of each single-component gas can be quantified by combining a pre-stored Raman intensity-pressure corresponding relationship, so that the blood gas analysis result of the human body is determined.

The application discloses a mercury ion detection method and device and a preparation method of a nano-gold Raman enhancer, and is used for improving the detection accuracy of heavy metal mercury ions. The mercury ion detection method comprises the following steps: preparing a nano-gold Raman enhancer by using a chloroauric acid solution, a sodium citrate solution and a thiuram solution; adding the nano-gold Raman enhancer into a mercury ion reference solution; performing Raman spectrum detection on the mixture to generate a spectrum graph; determining a target characteristic peak from the spectrum graph as a discrimination basis for enhancing Raman scattering spectrum detection of mercury ions, and determining that the mercury ion concentration and the intensity of the characteristic peak are in a positive correlation relationship, the mercury ion reference solution is a solution with a known mercury ion concentration; adding the nano-gold Raman enhancer into a sample solution to be detected; performing Raman spectrum detection on the mixture, and calculating the mercury ion concentration in the sample solution to be detected according to the peak area of the known characteristic peak.

The application discloses a combined device for material surface and bulk phase testing, and belongs to the technical field of material analysis and testing. In order to study and analyze the micro-particle activity of the surface and bulk phase structure of a lithium ion battery multi-layer structure, the combined device comprises a hard X-ray photoelectron spectrometer (1) and an X-ray Raman scattering spectrometer (2). When incident hard X-rays (31) are obliquely incident on a sample (41) located at a sample point (4), electrons can be excited and photons can be scattered. The hard X-ray photoelectron spectrometer (1) can detect the electrons, and the X-ray Raman scattering spectrometer (2) can detect the photons. The combined device is based on a synchrotron radiation light source facility, and combines the hard X-ray photoelectron spectroscopy and the hard X-ray Raman scattering technology to be applied to lithium ion battery testing. The specific structure is simple, and the lithium ion battery can be subjected to synchronous analysis of the surface layer and the bulk phase structure.

The utility model discloses an automatic focusing Raman spectrometer which comprises a first shell, a fixing block is fixedly connected in the first shell, a driving assembly used for power output is fixedly connected in the fixing block, the output end of the driving assembly is fixedly connected with a driving shaft, and the driving shaft is fixedly connected with a focusing device. A transmission gear is fixedly connected to the exterior of the driving shaft, a rotating shaft is rotatably connected to the interior of the fixing block, a driven gear is fixedly connected to the exterior of the rotating shaft, and a tray is fixedly connected to the top of the driven gear. According to the structure, the fixing plate is fixed at the top of the sliding block, the laser is arranged on the surface of the fixing plate, the focusing ring outside the light filter can be adjusted through the light filter at the top of the fixing block in cooperation with the laser to irradiate the surface of a sample on the tray, the Raman scattering phenomenon is triggered, and therefore the characteristic peak in a Raman scattering spectrum can be observed more clearly; the molecular structure of the sample can be accurately analyzed.

The application belongs to the technical field of surface enhanced Raman scattering spectrum, and particularly discloses a silver nanometer@ZIF-8@gold nanometer composite substrate and a preparation method and application thereof. The silver nanometer@ZIF-8@gold nanometer composite material provided by the application takes the silver nanometer ball with a particle size of 100-400 nm as a core, the silver ball is wrapped with a ZIF-8 film with a thickness of 1-10 nm, and the gold nanometer ball with a particle size of 30-50 nm is attached to the outer layer of the silver core ZIF-8 shell. The excellent material ZIF-8 in the MOF is combined with the two kinds of noble metal materials of gold and silver, and the noble metals form a multiple enhancement effect. Meanwhile, the design of taking the silver nanometer ball as the core, the ZIF-8 as the shell and the gold nanometer ball being uniformly attached to the surface of the core-shell avoids the plugging problem of the noble metal nanometer ball to the MOF material to a certain extent, improves the adsorption performance of the substrate and increases the number of the substrate surface "Raman hot spots", and greatly improves the detection sensitivity of the substrate.

A method for applying a primary reference standard measurement and for potential adjustment and / or calibration of high-sensitivity optical spectrometry instruments via a computer, comprising the following steps of Using a high-purity H2O solution as a primary standard stored in a container; Exciting the standard using at least one excitation laser; Collecting and measuring the Raman scattering, either in form of Stokes, Anti-Stokes, or both, from the standard using the instrument's detector; Applying a correction methodology for correction of variations in the Raman scattering caused by the container to increase accuracy of measurement; Measuring and integrating the intensity over a fixed detection bandwidth of the spectrum of the Raman scattering to calculate the instrument optical efficiency; and potential adjustment and / or calibration of the high-sensitivity optical spectrometry instrument based on the calculated instrument optical efficiency.

The Raman scattering spectroscopic method according to the present invention include: preparing a chip having a channel in which a nanostructure is formed; introducing an analyte solution into a part of the channel in the chip; irradiating an interface of the analyte solution with a laser beam; and measuring Raman scattering light induced by the irradiation of the laser beam. The measurement may be performed, with a fixed laser beam irradiation position, both in a state where the interface of the analyte solution is included in the laser-beam-irradiation area and in a state where the interface of the analyte solution is not included in the laser-beam-irradiation area, or may be performed keeping the state where the interface of the analyte solution is maintained in the laser-beam-irradiation area by controlling the laser-beam-irradiation area according to the movement of the interface due to evaporation of the analyte solution.

The utility model provides a bursaphelenchus xylophilus infectious disease detector based on a Raman scattering spectrum analysis technology, and particularly belongs to the technical field of infectious disease detection. A Raman spectrum imaging module, a data acquisition module, a data comparison module and a result output module form a core module of the device, so that light path design and a CNN algorithm are optimized, the signal-to-noise ratio of the device is improved by 30%, the classification accuracy rate reaches 97.2%, trace metabolite change in the early stage of infection can be detected, the infection incubation period is shorter than 7 days, and the detection accuracy is improved. Therefore, the device has the characteristics of high sensitivity and specificity. The device comprises a laser fixing support and a beam splitter prism assembly, and further comprises a light filtering module and a sample bin. Four-corner buckles are arranged on the inner side of the laser fixing support, the laser fixing support is used for installing the laser through the buckles, the beam splitter prism assembly is installed on one side of the laser, the light filtering module is installed on the other side of the beam splitter prism assembly, and the sample bin is installed on the other side of the light filtering module.

A corrosion detecting composition comprising a nanoparticle and at least one chemically reactive adsorbate associated with the nanoparticle. The chemically reactive adsorbate displays a responsive surface enhanced Raman scattering (SERS) spectral response that is a function of pH. The nanoparticle is contained in a selective carrier; such that the selective carrier allows transport of protons or hydroxide anions to the chemically reactive adsorbate associated with the nanoparticle. Lastly, the selective carrier restricts transport of organic chemical compounds to the at least one chemically reactive adsorbate. This allows the Raman sensor molecules to be blended with paints and coatings prior to application on metal surfaces, and the Raman sensor molecules do not prematurely react with the components of paints or coatings. A Raman detectors can be used to non-destructively interrogate the Raman sensor molecules and detect the pH changes associated with undercoat corrosion.

A synthetic single crystal diamond which contains nitrogen atoms at a concentration of 200 ppm to 1500 ppm (inclusive) on the basis of the number of atoms, the Raman shift [lambda] 1 cm-1 of the peak in the primary Raman scattering spectrum of the synthetic single crystal diamond and the Raman shift [lambda] 2 cm-1 of the peak in the primary Raman scattering spectrum of the synthetic IIa type single crystal diamond having a nitrogen atom number-based concentration of 1 ppm or less show the relationship of formula A:-0.85 lt; formula A: [lambda] 1-[lambda] 2 < =-0.15.

An analytical method and system for monitoring cellular status wherein excitation energy is focused into an excitation cytometry volume within a cell sample that is located within a bioreactor or fermenter to induce optical signals from intracellular compounds. The resulting optical signals are directed to a detection subsystem that has at least two detection channels. One channel detects the elastic (Rayleigh or Mie) scattering signal from the cell that identifies the presence of the cell within the excitation volume. Another channel detects the fluorescence and / or Raman scattering signal of intracellular compounds of the cells. The elastic scattering signals associated with individual cells are used as event-triggers to gate the detection of the intracellular fluorescence and / or Raman signal to eliminate the background noises from the suspension media. The intracellular fluorescence and / or Raman scattering signal are used to characterize cellular status based on the fluorescence intensities at specific fluorescence wavelengths and peak analysis of Raman scattering spectra.