55 results about "Marker enzymes" patented technology

Provided is a ultra-high-sensitivity assay in which the assay can be made on a commonly used assay apparatus such as an absorptiometer and a plate reader or with naked eyes. The high-sensitivity assay in which the assay can be made on a commonly used assay apparatus or with naked eyes can be provided by combining an enzyme cycling method using thio-NAD(P) as a coenzyme, a labeling enzyme and a substrate for the labeling enzyme optimally, and by amplifying thio-NAD(P)H, which is a signaling substance, exponentially and then quantifying the thio-NAD(P)H colorimetrically.

The invention discloses an acridinium ester derivative, a synthesis method and application thereof. The chemiluminescent acridinium ester derivative provided by the invention has a structural formula shown as formula I. The invention further discloses a synthesis method for the compound shown as formula I, and the method includes: (1) synthesizing acridine-9-thiocarboxylic acid p-trifluoromethylbenzene ester; (2) synthesizing 10-methyl-acridine-9-thiocarboxylic acid p-trifluoromethylbenzene ester; (3) synthesizing 10-methyl-9, 10-dihydroacridine-9-thiocarboxylic acid p-trifluoromethylbenzene ester; and (4) synthesizing TfS-APS. The acridinium ester derivative provided by the invention can be used as an immunoassay tracer to a chemiluminescence immunoassay reagent system with alkaline phosphatase (ALP) as the marker enzyme. The application effect in a kit proves that the acridinium ester derivative involved in the invention can detect 1*10<-19>mol ALP molecules, and has the advantages of high sensitivity, long luminescence duration, simple use, constant intensity under room temperature condition, and no need for precise temperature control, etc.

The method for measuring the concentration of the measuring object uses a sensor chip comprising an optical waveguide layer and an antibody immobilized layer formed on the surface of the optical waveguide layer, which comprises immobilizing the measuring object and an enzyme-labeled antibody labeled with a labeling enzyme on the antibody immobilized layer of the sensor chip having an immobilized antibody, producing a color-developing and precipitating enzyme reaction product by allowing to react a coloring reagent with the labeling enzyme on the antibody immobilized layer to precipitate the enzyme reaction product on the antibody immobilized layer, allowing to totally reflect a light impinged on the sensor chip from the outside at an interface between the optical waveguide layer and the antibody immobilized layer, and observing to a physical value of the totally reflected light.

A hepatitis c virus antigen-antibody joint detection reagent box is characterized by comprising a calibrator(1), a double-marker enzyme conjugate (2), a negative and positive contrast (3), light-emitting liquid (4) and a micropore coated plate (5), wherein the light-emitting liquid contains light-emitting liquid 1 and light-emitting liquid 2, the light-emitting liquid 1 contains luminal 0.7 g / L, cinnamic acid 0.9 g / L, 4-iodophenylboronic acid 0.2 g / L, iodobiphenol 0.25 g / L, dimethylformamide 25 ml / L, polyving akohol 5 g / L, polyvinylpyrrolidone 8 g / L, polyethylene glycol 600 3 g / L, ethylenediamine tetraacetic acid 4 g / L, gentamicin sulfate 1600 thousands / L, urea peroxide 0.4 g / L, and pH 9.0 Tris buffer solution 0.1 mol / L. The light-emitting liquid 2 contains acridinium ester derivative 0.1 mg / ml, polyethylene glycol 600 3 g / L and 0.1 mol / L of pH 9.0 Tris buffer solution containing 0.1% of TWEEN-20. The invention further discloses a preparation method and a using method of the reagent box. The hepatitis c virus antigen-antibody joint detection reagent box has the advantages of being quick in reaction and low in cost.

This invention provides a human hypothyroid peroxid enzyme antibody magnetic separation enzyme immune measurement method, whose steps are the following: to add sample to react with immune; to wash and to join two anti-enzyme indicate reagent and to wash again; to add monophosphatase fenolftaleina substrate solvent; to terminate color forming and to read absorbing value. The advantages in this invention are the following: it uses reformed human hypothyroid peroxid enzyme antigen fold immune magnetism micro ball as fixed phase and uses alkalescence phosphate enzyme as mark enzyme. Through the quantitative measurement of peroxid enzyme antigen of the hypothyroid patient and normal serum and other clinic symptom, it can judge whether the patient has got the self-immune hypothyroid illness.

The invention provides a thyrotropin (TSH) chemiluminescent immunoassay quantitative detection kit and a preparation method thereof. The invention has the advantages that the reaction pattern of the double antibody sandwich method is adopted, the chemiluminescent technology combining with the technology of fluorescin isothiocyanate-anti-fluorescein isothiocyanate is effectively utilized, horse radish peroxidase is adopted to be as the marker enzyme to quantitatively detect the content of TSH in the human serum sample, the detection sensitivity is guaranteed, and the raw materials are greatly saved. The kit of the invention has high sensitivity, good repeatability, short reaction time, good stability and long reagent validity, and can provide the experimental basis timely for the clinical diagnosis and the treatment of thyroid disorders.

The invention provides a chemiluminescent immunoassay kit for thyroid peroxidase autoantibodies and a preparation method thereof. The invention has the advantages that the reaction pattern of the double antigen sandwich method is adopted, the chemiluminescent technology and the biotin-avidin immune amplifying technological principle are effectively utilized, horse radish peroxidase is adopted to be as the marker enzyme, the content of the thyroid peroxidase autoantibodies in human serum samples is quantitatively detected, and the detection sensitivity can be ensured. The kit of the invention has the advantages of high sensitivity, good repeatability, good stability and high detection efficiency, and can provide a timely and reliable experimental basis for the clinical diagnosis and the treatment of thyroid disorders.

The invention belongs to the technical field of in-vitro detection, and particularly relates to a detection kit and a preparation method and application thereof. The detection kit comprises a magneticseparation reagent and an enzyme-labeled reagent; the magnetic separation reagent is prepared from troponin T antibody-coated gold magnetic particles or prepared from streptavidin-coated gold magnetic particles and a biotin-labeled troponin T antibody; and the enzyme-labeled reagent is prepared from an enzyme-labeled antibody polymer, wherein the enzyme-labeled antibody polymer is prepared from at least two enzyme-labeled antibodies and carbon bridges; the carbon bridges connect any two or more, adjacent or non-adjacent enzyme-labeled antibodies, and each carbon bridge has at least two connecting loci for connecting the enzyme-labeled antibodies; and each enzyme-labeled antibody is prepared from a detection antibody and a labeling enzyme coupled to the detection antibody, and the connecting loci are connected with the detection antibodies and / or the labeling enzymes. When chemiluminescence detection is conducted, a reaction signal value of a chemiluminescence method is amplified, thesensitivity of an antigen captured by the detection reagent can be enhanced, and the detection sensitivity is improved.

The invention provides a novel ELISA (Enzyme Linked Immunosorbent Assay) method with high detection sensitivity. The detection sensitivity of the novel ELISA method can reach 100 times of that of an existing ELISA method. In the novel ELISA method, a more sensitive novel fluorogenic substrate is used for replacing a chemical chromogenic substrate in the conventional ELISA method; moreover, a high-efficiency stable enzyme capable of catalyzing the fluorogenic substrate to generate a luminescent effect is used as a marker enzyme so as to realize that the luminescent effect of the substrate reaches the minimum enzyme quantity required for the detectable level; the novel ELISA method also uses a gold nanoparticle coupling streptavidin system with excellent biocompatibility for realizing an amplification effect of an enzymatic reaction; integration of improvement measures on the three aspects finally implements great improvement on the detection sensitivity of the ELISA method.

The invention discloses a biological chip adopting soybean peroxidase (SBP) for marking, and a preparation method thereof. The chip includes a nitrocellulose membrane coated by captured monoclonal antibodies, a biotin-marked polyclonal antibody, SBP-marked streptavidin, and an enhanced chemiluminescent solution where SBP acts, wherein the captured monoclonal antibodies and the biotin-marked polyclonal antibody can all achieve specific binding with an antigen to be detected. The invention has the advantages that the SBP replaces horseradish peroxidase in the prior art to be a marker enzyme for the biological chip preparation, so as to maintain intense chemiluminiscence for a longer time, and achieve much higher detection sensitivity.

The invention discloses an enzyme-labeled immunoassay kit which comprises an antibody pre-coating reaction plate, an enzyme-labeled antibody and luminous substrate liquid, wherein the enzyme-labeled antibody takes SBP (soybean protease) as marker enzyme; the luminous substrate liquid comprises H2O2, luminol and an enhancer; the enhancer consists of MORPH (4-marlene pyridine) and SPTZ (3-(10'-phenothiazinyl) propyl-1-sulfonate). According to the enzyme-labeled immunoassay kit, the SBP is introduced to serve as the marker enzyme; on one hand, the thermal stability of the enzyme is higher than that of HRP (hypothalamic regulatory peptide), and the enzyme has the advantages of wide substrate working range, high heat resistance, high acid-alkaline stability, wide pH application range and the like; on the other hand, when the enhancers MORPH and SPTZ are used for enhancing chemical illumination, a chemical luminous signal is enhanced by nearly 100 times, and the detection sensitivity is greatly improved.

The invention discloses a multi-index combined-detection chemiluminiscence immunoassay method for forming quantum dot-enzyme complex based on quantum dot marker enzyme. The multi-index combined-detection chemiluminiscence immunoassay method for forming quantum dot-enzyme complex based on quantum dot marker enzyme comprises the following steps: marking quantum dots in different particle sizes or varieties on an enzyme surface or a polymer layer surface 5-10nm distancing from the enzyme, thereby forming different quantum dot-enzyme complex; the absorption spectrums of the quantum dots in different particles sizes or varieties and the enzyme are used for catalyzing the luminescent substrate to produce the emission spectrums, and the emission spectrums are sufficiently overlapped, and the quantum dots have large Strokes displacement, the emission light in 400-600nm wavelength produced by catalyzing the substrate by the enzyme can be efficiently converted into the emission light in the wavelength of 500-750nm, and the detection is performed under the effect of different optical filters; and the multi-index combined detection can be quickly and efficiently performed on a chemiluminescence platform by using less sample.

The present invention relates to a composition containing extracts of Litchi seed for preventing or treating fatty liver or obesity. The composition of the present invention may induce the reduction of body fat mass, intestinal fat mass, total cholesterol concentration, levels of C / EBPa and PPAR?2 which are important factors of nuclear transcription in generating fat tissue, and the expression amounts of the aP2 gene which is the target gene of C / EBPa and PPAR?2, and eventually activate the prevention or treatment of obesity. The composition of the present invention may inhibit the progression of fatty liver diseases and treat same by maintaining the morphological, structural, and physiological functions of the liver, in addition to having the effect of preventing the development said fatty liver diseases.; Moreover, the composition of the present invention may improve fat accumulation in liver tissue by reducing the lipid content level in the liver tissue, and may have the effects of preventing the development of fatty liver, inhibiting the progression or improving the condition of patients by normalizing liver function marker enzyme expression. In addition, the present invention provides preliminary data showing that Litchi seed extracts, as a medicinal material and food, are efficacious in preventing and treating fatty liver diseases.

The invention relates to a detection kit for detecting a tumor marker, which belongs to the detection field of analysis. An immune magnetic ball which is covalently coupled with a tumor marker antibody is used as a solid vector of the immune reaction, an immune magnetic separation technology is used for separating and gathering the target tumor markers, a catalytic signal of a marker enzyme is converted into metal nano particles deposited on the surface of a liquid crystal sensitive membrane to disturb liquid crystal molecules according to an enzymatic metallization signal conversion and amplification strategy, so that the visual detection of the target tumor marker can be realized. According to the method, the immune magnetic separation technology is combined with the enzymatic metallization and a liquid crystal biosensor to establish a liquid crystal immunoassay based on the immune magnetic separation, so that the problem that when the liquid biosensor is applied to the immunoassay,the sensitivity is low, and the interference resistance is low can be solved. The method has the characteristics of high sensitivity, simplicity in operation, no need of complicated instruments, visualized detection result and the like and can be directly used for detecting the tumor marker in a complicated sample.

The invention relates to an enzyme-labeled secondary antibody compound and a preparation method thereof, and belongs to the technical field of immunoassay. The enzyme-labeled secondary antibody compound comprises a polymer skeleton and a labeling enzyme. The labeling enzyme is connected to the polymer skeleton through a coupling agent, and a secondary antibody is connected to the labeling enzyme through a coupling agent; wherein the polymer skeleton is provided with a branched chain end part and a middle branch structure connected with the branched chain end part, and the labeling enzyme is connected to the branched chain end part and the middle branch structure of the polymer skeleton through a coupling agent; and the polymer skeleton is a hyper-branched polymer skeleton. The branched chain end part and the middle branch structure of the polymer skeleton can be connected with a coupling agent, so that the sensitivity of the enzyme-labeled secondary antibody compound is favorably improved, and the accumulation mode of enzyme and antibody is favorable for improving the polymerization degree of enzyme and antibody in the polymer, so that the sensitivity of the enzyme-labeled secondary antibody compound in immunoassay is greatly improved.

The invention discloses a preparation method and application of a two-photon ratio type fluorescent probe in precisely detecting monoamine oxidase B in tumor cells. The probe consists of a two-photonnaphthalene derivative biological framework based on fluorescence resonance energy transfer, and p-methylaminophenol fluorophore which are connected together, and a propylamine unit which is introduced for specific recognition of monoamine oxidase B. Corresponding imine ions are generated through an enzymatic oxidation deamination reaction, are further hydrolyzed and eliminated, then dye hydroxylis released for another time, and the ratio of fluorescence emission signals can be changed. The advantages are that the distance of fluorescent spectrums of energy donors and acceptors is enlarged, interference of spectrums is reduced, the sensitivity is high, and interference of various environment conditions upon analysis is effectively avoided. A potential tool is provided for clinical detection on significant marker enzymes of Alzheimer's disease in living bodies.

The invention discloses a qualitative detection kit for antibody to hepatitis C (anti-HCV), which comprises calibration liquid, a negative control product, a positive control product, an anti reagent, a magnetic particle reagent and a luminescent substrate. An alkaline phosphatase is taken as a marker enzyme, and directly marks an anti recombinant antigen by chemical reaction; fluorescein is taken as a marker bridge and directly marks the anti recombinant antigen by chemical reaction; immune magnetic particles are taken as a solid phase, goat-anti fluorescein isothiocyanate antibody is coupling magnetic microspheres are taken as a universal separating reagent; a novel chemiluminescent substrate ALPS is taken as a substrate; the kit is reliable in performance, high in sensitivity and good in specificity and can be used in match with semiautomatic and full automatic instruments. A coincidence rate of positivity and negativity of a national reference product is 100 percent by determining, a clinical coincidence rate is up to 99.7 percent and the kit is suitable for anti-HCV detection and screening.

The invention discloses an application of miR-296 and a simulant thereof in promoting osteogenic differentiation of bone marrow mesenchymal stem cells and bone formation. The regulation effect of themiR-296 on osteogenic differentiation of the bone marrow mesenchymal stem cells and bone formation is explored through in-vitro experiments. In-vivo experiments prove that the formation of new bones can be promoted through the transfection of the miR-296, and the in-vitro experiments prove that the miR-296 can improve osteogenic differentiation ability of the bone marrow mesenchymal stem cells andpromote in-vivo bone formation by promoting the formation of osteoblast calcium nodules and the activity of a marker enzyme ALP, as well as promoting the expression of Osterix and Runx2 which are important regulatory transcription factors in the process of osteogenic differentiation. The invention provides a new technical means for the treatment of osteoporosis.

The invention relates to a method for detecting alkaline phosphatase and cardiac troponin I in real time through in-situ fluorescence reaction initiated by copper ions and application. According to the method, dopamine and phenol (1, 3-naphthalene diphenol, 8-hydroxyjulolidine and 1, 5-naphthalene diphenol) are taken as raw materials, and a fluorescent compound (FCs) with high fluorescence intensity, good stability and adjustable wavelength is synthesized in a room-temperature water phase. Under the initiation of Cu <2+>, dopamine and different phenols can obtain the fluorescent substances with different emission wavelengths, and the affinity of pyrophosphate ions (PPi) to Cu <2+> is utilized to realize the fluorescence closing of a system. Under the catalytic hydrolysis of alkaline phosphatase (ALP), PPi can be quickly converted into phosphate ions, so that the fluorescence of the system is opened. A multi-channel immunofluorescence sensing platform is constructed by taking cardiac troponin I as a targeting antigen and taking alkaline phosphatase as a marker enzyme. In addition, a sensing system still shows rapid response and good recovery rate in human serum.

The invention discloses a kit for detecting furaltadone metabolites in a food. The kit comprises an ELISA plate coated with a furaltadone metabolite antigen, a furaltadone metabolite monoclonal antibody, a verdoperoxidase-labelled goat anti-mouse antiantibody, a standard solution, a substrate developing solution, stop buffer, concentrated scrubbing solution and concentrated reconstitution fluid. The furaltadone metabolite antigen is a conjugate of furaltadone metabolite half antigen and keyhole limpet haemocyanin; and the verdoperoxidase-labelled goat anti-mouse antiantibody is obtained by coupling marker enzyme verdoperoxidase and a goat anti-mouse antiantibody through a glutaraldehyde crosslinking method. The kit is high in sensitivity and stability and suitable for aquatic products such as fishes and shrimps and animal products such as chicken and pork.

The invention relates to the technical field of biology and provides a staining agent for staining horse radish peroxidase and a preparation method of the staining agent, a staining composition, an application and a marker enzyme staining kit. The staining composition comprises the following reagents: diaminobenzidine, nickel ammonium sulfate, glucose, ammonium chloride, glucose oxidase, acetic acid and sodium acetate. The staining composition can be applied to preparation of the marker enzyme staining kit. The kit comprises the staining composition. The staining agent is prepared from the staining composition by the processes of preparing a diaminobenzidine water solution from diaminobenzidine as a first mixture; preparing a nickel ammonium sulfate water solution from nickel ammonium sulfate as a second mixture; mixing the glucose, the ammonium chloride and the glucose oxidase to form a third mixture; preparing a sodium acetate water solution from the acetic acid and the sodium acetate as a fourth mixture; and mixing the first mixture and the second mixture, then mixing with the third mixture and finally mixing with the fourth mixture. The preparation method is simple in procedure.

A hepatitis c virus antigen-antibody joint detection reagent box is characterized by comprising a calibrator(1), a double-marker enzyme conjugate (2), a negative and positive contrast (3), light-emitting liquid (4) and a micropore coated plate (5), wherein the light-emitting liquid contains light-emitting liquid 1 and light-emitting liquid 2, the light-emitting liquid 1 contains luminal 0.7 g / L, cinnamic acid 0.9 g / L, 4-iodophenylboronic acid 0.2 g / L, iodobiphenol 0.25 g / L, dimethylformamide 25 ml / L, polyving akohol 5 g / L, polyvinylpyrrolidone 8 g / L, polyethylene glycol 600 3 g / L, ethylenediamine tetraacetic acid 4 g / L, gentamicin sulfate 1600 thousands / L, urea peroxide 0.4 g / L, and pH 9.0 Tris buffer solution 0.1 mol / L. The light-emitting liquid 2 contains acridinium ester derivative 0.1 mg / ml, polyethylene glycol 600 3 g / L and 0.1 mol / L of pH 9.0 Tris buffer solution containing 0.1% of TWEEN-20. The invention further discloses a preparation method and a using method of the reagent box. The hepatitis c virus antigen-antibody joint detection reagent box has the advantages of being quick in reaction and low in cost.

The invention discloses an application of miR-92b and a simulant thereof in promoting osteogenic differentiation of bone marrow mesenchymal stem cells and bone formation. The regulation effect of themiR-92b on osteogenic differentiation of the bone marrow mesenchymal stem cells and bone formation is explored through in vitro experiments. The miR-92b can be proved to improve osteogenic differentiation ability of the bone marrow mesenchymal stem cells and promote in-vivo bone formation by promoting the formation of osteoblast calcium nodules and the activity of a marker enzyme ALP, as well as promoting the expression of Runx2 which is important regulatory transcription factors in the process of osteogenic differentiation. The invention provides a new technical means for the treatment of osteoporosis.

The invention relates to an enzyme-labelled coupled secondary antibody. The enzyme-labelled coupled secondary antibody is formed by coupling and connecting a modified antibody and a modified labelled enzyme through an oxime bond, wherein the modified antibody is formed by connecting amino of an antibody lysine residue with an amino oxygen group in a modified manner, and the modified labelled enzyme is formed by connecting amino of a lysine residue of an enzyme molecule with aryl aldehyde in a modified manner. The enzyme-labeled coupled secondary antibody is stable in structure, moderate in size, high in sensitivity, good in specificity, free of non-specific staining due to interference of biotin existing in organism tissue, moderate in structure and size, especially suitable for detection of some intracellular antigens, and very high in sensitivity.

The invention discloses a visible tracking and detecting method for protease in a leather treatment process. The visible tracking and detecting method comprises the following steps of firstly, under an alkaline condition, marking protease through fluorescein isothiocyanate (FITC) to obtain FITC marker enzyme, then treating a skin block without furs with the marker enzyme under room temperature and shading conditions, and preparing a slice from the skin block treated by the marker enzyme to observe a distribution state of the enzyme in the skin under a fluorescence microscope. According to the visible tracking and detecting method, the permeability of the enzyme in the skin and the acting degree of the enzyme to the skin can be detected according to the strong fluorescence characteristic of the FITC, and a permeation mode of the enzyme in the skin can be obtained according to the difference of treatment time. The enzyme firstly permeates into the skin through pores and the peripheries of hair follicles and then gradually diffuses into a skin substrate to act on fibrous stroma proteins. According to the visible tracking and detecting method, a theoretical basis is supplied to the application of the enzyme to manufacturing of leather; enzyme with proper molecular weight is selected for treating collagen according to fiber structures of the collagen in different treatment stages of manufacturing of leather, and the controllable treatment of enzyme on the leather protein and the collagen is realized by analyzing the permeability and the acting degree of the enzyme in the collagens.

The invention relates to the technical field of animal pathogenic antibody detection and discloses an ELISA kit for detecting some animal pathogenic antibody. The ELISA kit comprises a pre-coated plate, a to-be-detected antibody labeled by a marker enzyme, a coating buffer solution, a washing buffer solution, a terminating solution, a primer buffer solution, a TMB using solution and an ABTS usingsolution. The pre-coated plate is a 96 porous polystyrene board, the marker enzyme is horse radish peroxidase, the coating buffer solution is a carbonate buffer solution, the pH value of which is 9.6,the coating buffer solution is prepared by mixing 1.59 g of Na2CO3, 2.93g of NaHCO3 and 1000 mL distilled water, and the washing buffer solution is a phosphate buffer solution, the pH value of whichis 7.4. The ELISA kit for detecting some animal pathogenic antibody can extract a to-be-detected antibody from feces of a pig without fixing the pig and sampling blood serum from the pig, so that theworking flow is simplified, and the influence on healthy growth of the pig when the blood serum is sampled is avoided effectively.

The invention discloses a food safety carrier established by utilizing cellulose incision enzyme and beta-glucosaccharase, and a selection medium, which belong to the field of gene engineering. The food safety carrier adopts the cellulose incision enzyme and the beta-glucosaccharase as selection markers, contains a cellulose incision enzyme encoding gene and a beta-glucosaccharase encoding gene, and can express the cellulose incision enzyme and the beta-glucosaccharase. The selection medium of the carrier has no carbon source directly utilized by a microorganism, and contains carboxymethyl cellulose sodium and gardenia blue. The cellulose incision enzyme encoding gene and the beta-glucosaccharase encoding gene are cloned to the carrier so as to obtain the food safety carrier. According to the food safety carrier established by utilizing the cellulose incision enzyme and the beta-glucosaccharase, and the selection medium provided by the invention, the cellulose incision enzyme and the beta-glucosaccharase are used as selection marker enzymes, and meanwhile, the special selection medium is utilized, so that transformants can be quickly and accurately selected; since the selection markers are not antibiotics, the carrier is the food safety carrier.

The invention discloses a nano antibody PRV-DND for specifically targeting a PRV, and discloses an amino acid sequence of the nano antibody. Meanwhile, the invention provides a preparation method of the nano antibody PRV-DND or the fusion protein PRV-DND-HRP. Particularly, a fusion protein formed by coupled labeled enzymes is used as a competitive probe, competitive ELISA for detecting the PRV antibody in a sample is provided, and based on the advantages of small molecular weight and easy genetic engineering modification of the nano-antibody, fusion expression can be performed on the nano-antibody and enzyme or fluorescent protein and the like, so that the nano-antibody can be directly applied to immunological detection, and the detection efficiency is improved. Antibody labeling and use of a secondary antibody are not needed, so that the production process is simplified, and the production cost is greatly reduced. Therefore, the nano antibody of the PRV antigen protein is screened and prepared, and the nano antibody is used as a material for immunological detection, so that the nano antibody has a very wide application prospect.