41 results about "Lead fluoride" patented technology

The invention provides a highly-active soldering flux suitable for stepped brazing of a magnesium-aluminum alloy, which comprises the following components by weight percent: 46.5-50.5 percent of aluminum fluoride, 40-42.5 percent of potassium fluoride, 1.5-2.5 percent of cesium fluoride, 2-4 percent of zinc fluoride, 1-1.5 percent of lithium fluoride, 2-4 percent of potassium fluosilicate and 0.5-1.5 percent of lead fluoride. The invention also provides a preparation method of the soldering flux. The invention has the advantage that the brazing temperature can reach above 590 DEG C. The soldering flux can be ground and prepared in atmosphere, has low preparation process cost, accurate finished product composition and high activity, is noncorrosive, is nonhygroscopic in air and can also be saved for a long time.

The invention relates to a method for hot preparation of hollow lead fluoride nanometer spheres by micro-emulsion assisted solvent, belonging to the technical field of preparation technology of inorganic nanometer materials. Adopting cyclohexane as the solvent, the method for hot preparation of hollow lead fluoride nanometer spheres by micro-emulsion assisted solvent uitlizes the precipitation reaction between hydrogen fluoride and lead ions and takes a surfactant as a soft template, to prepare the hollow lead fluoride nanometer spheres; wherein, the soft template is made from a plurality of surfactants, and the lead ions come from the soluble lead salts; the synthesized magnesium carbonate nanometer rods are provided with a diameter roughly between 30 and 100nm. Through the method for hot preparation of hollow lead fluoride nanometer spheres by micro-emulsion assisted solvent, the synthesized hollow lead fluoride nanometer spheres have the advantages of controllable size, low cost, simple preparation equipment, safe and easy operation, excellent performance of technique repeatability and stable products quality, and are suitable for the large-scale industrial production.

The invention discloses an infrared colorful false proof material and making method, which comprises the following steps: selecting certain proportional alumina, lead fluoride, beryllium fluoride, calcium fluoride, strontium fluoride, lanthanum fluoride, europium trioxide, samarium trioxide, thulium trioxide and gadolinium trioxide as raw materal; blending these raw materials; grinding; heating; insulating; heating again; quenching; cooling; grinding; packing. The spectral scale is broad to form 3-6 different colorful fluorescences stimulated by laser at 960nm, which is fit for falseproof marking material.

The invention relates to a lead fluoride crystal co-doped with ytterbium and alkaline and a preparation method thereof. The structural formula of the crystal is Ybx: My: PbF2, and the growth method of the crystal includes the following steps: (1) the values of x and y are determined; (2) the raw material is weighed in proportion, is fully and evenly mixed and is pressed into blocks, the blocks are put into an iraurite, platinum or plumbago crucible, PbF2 crystal is adopted as a seed crystal, growth atmosphere is high purity argon or CF4 gas, and melt growth method is adopted. Experiments show that the crystal of the invention has large absorption and emission section, long fluorescence life time and high thermal conduction.

The invention relates to the method used non vacuum falling crucible method to growth lanthanum chloride crystal. Its features are that the raw material is high pure LaCl3 containing crystal water; no water lanthanum chloride material is dehydrated under inert atmosphere at under 150 centigrade degree and preserved heat for 10-20h. Deoxidizer is one of activated carbon, crystalline flour, lead fluoride or carbon tetrachloride. Static double warm areas furnace structure is adopted. Micro motor drive speed adjusting gear is used to make crucible descend with adjustable constant speed. It has simple operation, low cost, and good performance, and is fit for large-scale production. The formed Ce: LaCl3 crystal can be applied to nuclear medicine imaging SPECT, nuclear radiation detecting, safety inspection, and geologic prospecting.

The invention relates to a 1064nm lead fluoride based up-conversion luminescence material and a preparation method thereof, and belongs to the technical field of luminescence materials. Present fluoride up-conversion luminescence materials are only responsive to 980nm light. The 1064nm lead fluoride based up-conversion luminescence material is characterized in that the general formula of the 1064nm lead fluoride based up-conversion luminescence material is (Pb1-xMx)F2:Er<3+>,Yb<3+>, M is one of Ca, Sr and Ba, x is not greater than 0 and is less than 1, and the 1064nm lead fluoride based up-conversion luminescence material can be excited by 1064nm wavelength light and can emit 551nm wavelength light. The preparation method of the up-conversion luminescence material is a high temperature solid phase method, reaction raw materials comprise fluorides of Yb and Er or comprise the fluorides of Yb and Er and a fluoride of one of Ca, Sr and Ba, and also comprise a fluoride of Pb, and the preparation method comprises the following steps: processing all the reaction raw materials to prepare a (Pb1-xMx)F2:Er<3+>,Yb<3+> precursor, wherein M is one of Ca, Sr and Ba, and x is not greater than 0 and is less than 1; carrying out grinding mixing of the precursor and a fusing assistant NaF to obtain a sintering material base; and putting the sintering material base in a crucible with the bottom spread with a layer of Na2SiF6, and carrying out a high temperature solid phase reaction in an open space to obtain the (Pb1-xMx)F2:Er<3+>,Yb<3+> target product.

The invention relates to a lead difluoride base material with Eu<2+> characteristic luminescence and a preparation method thereof. The chemical structure general formula of the base material is Pb1-x (Ca1-yEuy)xF2, wherein y is not less than 0.005 and not greater than 0.05 and x is not less than 0.05. The base material is prepared through codoping thermal treatment by taking PbF2 as a matrix and Ca1-yEuy as a codoping agent, wherein the codoping agent is prepared through thermal treatment with the temperature of 800-900 DEG C by taking CaF2 as a matrix and EuF2 or EuF3 as a doping agent. In the base material disclosed by the invention, Eu mainly exists in a form of Eu<2+> so that Eu<2+> characteristic luminescence (5d-4f transition) with a band spectrum and high attenuation speed is combined with an excellent Cherenkov luminophor (PbF2) with high density and relatively low price. Therefore, the lead difluoride base material with Eu<2+> characteristic luminescence can be applied to research of a PbF2-based double readable material (crystal / glass / ceramic) and has an important practical value in the research and application field of high energy physics.

The invention discloses an Er-Ho-Pr tri-doped lead fluoride mid-infrared laser crystal and a preparation method thereof. According to the invention, in a growing Er-Ho-Pr tri-doped lead fluoride crystal, as Er ions can be excited under 980nm LD, the transition of Er ions from <4>I11 / 2 to <4>I13 / 2 can generate fluorescence near 2.7 micrometers, at the same time a part of energy is transferred fromthe <4>I11 / 2 energy level of Er ions to the <5>I6 energy level of Ho ions, so that transition of Ho ions from <5>I6 to <5>I7 can generate fluorescence near 2.9 micrometers, therefore the full width athalf-maximum of a mid-infrared spectrum can reach 330nm; the incorporation of Pr ions not only enhances the energy transfer efficiency between the <4>I11 / 2 energy level of Er ions and the <5>I6 energy level of Ho ions, but also greatly reduces the <4>I13 / 2 energy level lifetime of Er ions and the <5>I7 energy level lifetime of Ho ions, is conducive to realizing population inversion and laser output, reduces the laser threshold and improves laser efficiency.

The invention relates to a dysprosium doped lead fluoride crystal which has a molecular formula of DyxPbF2+3x, wherein x is the doping concentration of Dy<3+> and is equal to 0.1-10 mol percent. The crystal grows by adopting a melt method. A preparation method of the dysprosium doped lead fluoride crystal comprises the following steps of: 1, selecting the value of x, weighting the initial raw materials of DyF3 and PbF2 in a crystal growing formula according to the molecular formula of the DyxPbF2+3x in accordance with the stoichiometric proportion, wherein x=0.1-10 mol percent; and 2, uniformly mixing the weighted raw materials in the proportion, drying in vacuum and pressing into blocks, placing a graphite or platinum crucible, with a PbF2 crystal as a seed crystal, growing gases of atmosphere of argon or CF4 and the like. The dysprosium doped lead fluoride crystal has lower phonon energy, longer fluorescence lifetime and larger absorbing and transmitting section, and is possible to apply to an all-solid laser of 2-5mum waveband.

The invention discloses an optical glass with high stability. The glass is characterized in that raw materials are composed of the following components by weight: 18 to 22 parts of silicon dioxide, 12 to 15 parts of calcium oxide, 2 to 4 parts of phosphorus pentoxide, 1 to 3 parts of aluminium oxide, 2 to 4 parts of metal oxides, 4 to 6 parts of lead fluoride, 2 to 3 parts of potassium oxide, 0.6 to 0.8 part of tellurium dioxide and 4 to 6 parts of basic cerium carbonate. According to the invention, production process of the basic cerium carbonate is simple and easy to realize, raw materials are cheap and easily available, product quality is stable, and repeatability is good, so the optical glass has good stability; the metal oxides can ease devitrification resistance of the glass, promote defoaming during melting of the glass and improve meltbility of the glass, so homogeneous optical glass is obtained; and prepared optical glass has high transmittance, high thermal stability parameter and high refractive index, wherein stimulated emission cross section of the optical glass can reach to 1.48pm2.

The invention discloses a fluxing agent for beta-Ga2O3 crystal growth and a crystal growth method based on the fluxing agent. According to the invention, B2O3-alkali metal oxide is used as a main material, a small amount of molybdenum oxide such as MoO3 and molybdate such as K2Mo2O7 and Na2Mo2O7 are used as auxiliary materials, and the molar ratio of B2O3-alkali metal oxide to molybdenum oxide to molybdate is (0.8-1.5): (0.8-2.5): (0-0.3) as a fluxing agent system for growth of beta-Ga2O3 crystals. The fluxing agent system provided by the invention does not contain toxic and harmful components such as lead oxide and lead fluoride which are commonly used in high-temperature fluxing agents, the crystal growth temperature interval is 950-1080 DEG C, the growth temperature of the crystal is effectively reduced, the solvent viscosity is small, the component volatilization is less, the high-temperature solution is clear and transparent, the crystal growth process is convenient to control in real time, and the obtained crystal is relatively good in quality; no wrapping phenomenon exists, and the high-quality beta-Ga2O3 crystal is easy to obtain.

The invention relates to a thulium doped lead fluoride crystal. The molecular formula of the crystal is TmxPbF2+3x, wherein x is the dosage concentration of Tm3+ and is 0.1-10mol percent. A melt method is used for the growth of the crystal and comprises the following steps of: (1) selecting the value of x, and weighing raw materials by a stoichiometric ratio according to the molecular formula TmxPbF2+3x, wherein initial raw materials for the crystal growth comprise TmF3 and PbF2, and x is 0.1-10mol percent; (2) sufficiently and uniformly mixing the raw materials weighed by the ratio, drying in vacuum and pressing into blocks; and putting the blocks into a graphite crucible or a platinum crucible by using a PbF2 crystal as a seed crystal with a growth atmosphere of argon or CF4 gas. The crystal has the advantages of long fluorescence lifetime of 10ms and larger absorption and emission cross section and is expected to be applied to lasers within a wave band of 2mum of all-solid laser diode pumping.

This invention relates to a nanostructured pyroceram and the sol-gal process thereof, concretely to a lead fluoride silica dioxide pyroceram and method for making same. The produced PbF2 .SiO2 nanostructured pyroceram body is characterized of high purity, good homogeneity, up to 30mm diameter, up to 1-5mm thickness, good transparency, and good mechanical property(microhardness up to 150kg / mm2).

The invention relates to the method used non vacuum falling crucible method to growth lanthanum chloride crystal. Its features are that the raw material is high pure LaCl3 containing crystal water; no water lanthanum chloride material is dehydrated under inert atmosphere at under 150 centigrade degree and preserved heat for 10-20h. Deoxidizer is one of activated carbon, crystalline flour, lead fluoride or carbon tetrachloride. Static double warm areas furnace structure is adopted. Micro motor drive speed adjusting gear is used to make crucible descend with adjustable constant speed. It has simple operation, low cost, and good performance, and is fit for large-scale production. The formed Ce: LaCl3 crystal can be applied to nuclear medicine imaging SPECT, nuclear radiation detecting, safety inspection, and geologic prospecting.

The invention provides amino drying static varnish. The amino drying static varnish is prepared from the following raw materials in parts by weight: 100-120 parts of polyphenylene sulfide, 30-40 parts of polytetrafluoroethylene, 40-50 parts of polyether-polysulfone, 30-40 parts of lead fluoride, 200-250 parts of water, 20-30 parts of surface active agent and 130-150 parts of propylene glycol. The amino drying static varnish is baked for 45 minutes at the temperature of 370 DEG C, a smooth coating with good adhesive force and high hardness can be formed, and the kinetic friction coefficient is not more than 0.155.

The invention discloses a 2.7-3 micrometer band intermediate infrared Yb-Er-Dy tri-doped lead fluoride laser crystal and a preparation method thereof. Specifically, Er<3+> ions act as activation ions,and Dy<3+> ions have the dual functions that: (1) as the energy level coupling ions of Er<3+> ions, Dy<3+> ions can reduce the <4>I13 / 2 energy level lifetime of Er<3+> ions; and (2) a small energy band gap exists between the <6>H11 / 2 energy level of Dy<3+> ions and the <4>I13 / 2 energy level of Er<3+> ions, energy transfer from the <4>I13 / 2 energy level of Er<3+> ions to the <6>H11 / 2 energy levelof Dy<3+> ions can be realized, and the energy level transition of Dy<3+> ions from <6>H13 / 2 to <6>H15 / 2 is facilitated, therefore 2.9 micrometer band fluorescence can be emitted. At the same time, Yb<3+> ions are introduced to solve the problem of low absorption efficiency of Er<3+> ions and Dy<3+> ions at the 970nm position and improve the crystal absorption efficiency.

The invention relates to a thulium doped lead fluoride crystal. The molecular formula of the crystal is TmxPbF2+3x, wherein x is the dosage concentration of Tm3+ and is 0.1-10mol percent. A melt method is used for the growth of the crystal and comprises the following steps of: (1) selecting the value of x, and weighing raw materials by a stoichiometric ratio according to the molecular formula TmxPbF2+3x, wherein initial raw materials for the crystal growth comprise TmF3 and PbF2, and x is 0.1-10mol percent; (2) sufficiently and uniformly mixing the raw materials weighed by the ratio, drying in vacuum and pressing into blocks; and putting the blocks into a graphite crucible or a platinum crucible by using a PbF2 crystal as a seed crystal with a growth atmosphere of argon or CF4 gas. The crystal has the advantages of long fluorescence lifetime of 10ms and larger absorption and emission cross section and is expected to be applied to lasers within a wave band of 2mum of all-solid laser diode pumping.

The invention relates to a method for measuring the content and distribution of elements in lead fluoride crystals. The method is used for analyzing the content and distribution of the elements in the lead fluoride crystals by taking a tablet prepared from lead oxide powder and a standard solution as a solid standard reference substance and taking 206Pb in the lead oxide powder as an internal standard element according to a laser corrosion inductance coupling plasma mass spectroscopy. By the adoption of a simple and quick standard sample preparation method, a solid reference substance with stable performance and high uniformity is obtained, and an obtained standard curve is higher in linear relevance, so that a high-purity lead fluoride sample can be quantitatively researched in a distributed manner. The method disclosed by the invention can be directly used for solid sample injection analysis without pre-treatment or preparation of a solid into a solution, and the distribution situation of the elements on the surfaces of the crystals can be also obtained.

The invention discloses a thulium-erbium-dysprosium triple-doped lead fluoride intermediate infrared laser crystal, a preparation method and application. In the crystal, erbium ions are used as activeions to realize fluorescence emission of 2.6-2.9 microns, corresponding to energy level transition of erbium ions from 4I11 / 2 to 4I13 / 2, and dysprosium ions are used as deactivation ions of erbium ions, on the one hand, dysprosium ions enable the service life of the lower laser energy level (4I13 / 2) of erbium ions to be shortened, and on the other hand, dysprosium ion 6H13 / 2-to-6H15 / 2 particle number inversion and intermediate infrared laser output are achieved; thulium ions have dual effects and serve as sensitizing ions of erbium ions and dysprosium ions or deactivating ions of erbium ions.The substrate material is a lead fluoride crystal, the physical and chemical properties and the optical properties are good, phonon energy is low, continuous, broadband tunable and ultra-short pulseintermediate infrared laser output can be achieved in a 3-micron waveband, and the thulium-erbium-dysprosium triple-doped lead fluoride intermediate infrared laser crystal has wide application prospects in the fields of military national defense, laser medical treatment and scientific research.

The invention belongs to the technical field of monocrystal growth, relates to an apparatus suitable for flux technology monocrystal growth, and especially relates to a flux technology growth apparatus and a method of rare earth doped orthophosphate crystals. The method comprises the following steps: mixing lead oxide with lead fluoride, compacting the lead oxide with lead fluoride to form a cylindrical block structure in order to obtain a flux, disposing a YbPO4 and YPO4 mixture in the bottom of an inner wall, compacting the mixture, and disposing the flux on the mixture; and screw-capping an upper cover on an outer wall, sealing the upper cover, disposing the growth apparatus in a heating furnace, adjusting the temperature of the heating furnace, heating to 800DEG C, and sequentially cooling to 750DEG C, 700DEG C, 600DEG C, 500DEG C and room temperature to end crystal growth. The apparatus adopted in the invention has the advantages of simple structure, convenient operation, low cost, less energy consumption, reduction of the energy loss due to reduction of the crystal growth temperature to 400DEG C, high dimensions and high quality of grown crystals, reduction of discharge of toxic substances, and environmental protection.

The invention relates to a praseodymium activated lead fluoride scintillation crystal material and a preparation method thereof. A chemical general formula of the praseodymium activated lead fluoride scintillation crystal material is PrxPbF2 + 3x, wherein x is 0.0005-0.01. Praseodymium (Pr) is introduced to lead fluoride crystals, the Pr content in the PrxPbF2 + 3x is controlled to be 0.0005-0.01, the lead fluoride crystals can produce flare light, the effect of a crystal field of fluoride ion matrix lead fluoride is strong, and the scintillating luminescence decay time of the praseodymium activated lead fluoride crystal is shortened.

The invention provides a praseodymium and holmium co-doping lead fluoride, alkali and yttrium up-conversion luminescent material. A chemical formula of the praseodymium and holmium co-doping lead fluoride, alkali and yttrium up-conversion luminescent material is shown in aPbF4-bRF-cYF3:xPr<3+>, yHo<3+>, wherein a is 0.1-0.24, b is 0.05-0.15, c is 0.55-0.7, x is 0.01-0.08, y is 0.01-0.06, and R is at least one of lithium element, sodium element, potassium element, rubidium element and cesium element. In a photoluminescence spectra of the praseodymium and holmium co-doping lead fluoride, alkali and yttrium up-conversion luminescent material, the excitation wavelength of the praseodymium and holmium co-doping lead fluoride, alkali and yttrium up-conversion luminescent material is 578nm, a glow peak is formed in a wavelength region of 483nm by virtue of transition radiation of Pr<3+>ion 3P0->3H4, and the praseodymium and holmium co-doping lead fluoride, alkali and yttrium up-conversion luminescent material can be used as a blue light luminescent material. The invention also provides a preparation method of the praseodymium and holmium co-doping lead fluoride, alkali and yttrium up-conversion luminescent material and an organic light-emitting diode by using the up-conversion luminescent material.

The invention relates to a method for measuring the content and distribution of elements in lead fluoride crystals. The method is used for analyzing the content and distribution of the elements in the lead fluoride crystals by taking a tablet prepared from lead oxide powder and a standard solution as a solid standard reference substance and taking 206Pb in the lead oxide powder as an internal standard element according to a laser corrosion inductance coupling plasma mass spectroscopy. By the adoption of a simple and quick standard sample preparation method, a solid reference substance with stable performance and high uniformity is obtained, and an obtained standard curve is higher in linear relevance, so that a high-purity lead fluoride sample can be quantitatively researched in a distributed manner. The method disclosed by the invention can be directly used for solid sample injection analysis without pre-treatment or preparation of a solid into a solution, and the distribution situation of the elements on the surfaces of the crystals can be also obtained.

The invention discloses a method for preparing a high temperature corrosion-resistant Mg-Pb-Al-B nuclear shielding material. The method includes the following operating steps that (1) Bi2O3, V2O5 andY2O3 are added into a ball grinding mill after being evenly mixed, acetone is further added, drying is performed after ball-milling treatment and mixed rare earth powder is obtained after sintering treatment; (2) after lead fluoride and barium fluoride are mixed, sintering treatment is conducted, and accordingly PbF2 / BaF2 eutectic powder is obtained; (3) magnesium powder, lead powder, aluminum powder, boron-containing intermediate alloy, the mixed rare earth powder and the PbF2 / BaF2 eutectic powder are added into the ball grinding mill, and spraying powder can be obtained after ball-milling treatment; and (4) after the spraying powder is sprayed onto the surface of a base body with a spray gun, the high temperature corrosion-resistant nuclear shielding material can be obtained. The nuclearshielding material prepared through the method not only has excellent nuclear shielding performance but also has splendid corrosion resistance in a high temperature environment, and the service lifeof the nuclear shielding material is greatly prolonged.

The invention discloses a 2.7-3 micrometer band intermediate infrared Yb-Er-Dy tri-doped lead fluoride laser crystal and a preparation method thereof. Specifically, Er<3+> ions act as activation ions,and Dy<3+> ions have the dual functions that: (1) as the energy level coupling ions of Er<3+> ions, Dy<3+> ions can reduce the <4>I13 / 2 energy level lifetime of Er<3+> ions; and (2) a small energy band gap exists between the <6>H11 / 2 energy level of Dy<3+> ions and the <4>I13 / 2 energy level of Er<3+> ions, energy transfer from the <4>I13 / 2 energy level of Er<3+> ions to the <6>H11 / 2 energy levelof Dy<3+> ions can be realized, and the energy level transition of Dy<3+> ions from <6>H13 / 2 to <6>H15 / 2 is facilitated, therefore 2.9 micrometer band fluorescence can be emitted. At the same time, Yb<3+> ions are introduced to solve the problem of low absorption efficiency of Er<3+> ions and Dy<3+> ions at the 970nm position and improve the crystal absorption efficiency.

The invention discloses a novel medium-infrared laser crystal of a ytterbium, holmium and dysprosium-doped lead fluoride and a preparation method of the novel medium-infrared laser crystal. Holmium ions act as activating ions to realize a fluorescence output of 2.7 to 3.1 micrometers, and corresponding luminescence energy level transition is holmium: 5I6 to 5I7; ytterbium ions act as sensitizing ions to solve the problem of low absorption efficiency of the holmium ions at a commercial high-power LD pump; dysprosium ions have two effects; on one hand, the dysprosium ions shortens the life of the lower energy level (5I7) of the holmium ions, and the energy level life of the upper energy level (5I6) of the cesium ion does not change obviously, thus beneficially achieving the holmium: 5I6 to 5I7 population inversion and the mid-infrared laser output of the holmium ions; on the other hand, by energy transfer from holmium: 5I7 to dysprosium: 6H13 / 2, the number of particles on the upper energy level (6H13 / 2) of the dysprosium ions is increased, and dysprosium: 6H13 / 2 arrow 6H15 / 2 population inversion and mid-infrared laser output of the dysprosium ions are achieved.

The invention relates to a Yb and Pr co-doped lead fluoride blue, green and near-infrared laser crystal and a preparation method and application thereof. The chemical formula of the crystal is YbxPryPb1-x-yF2, the value range of x is 0.01-0.04, the value range of y is 0.001-0.005, the space group of the crystal is Fm-3m (225), the crystal belongs to a cubic system, and in the doping concentration range, and the unit cell parameter range is described in the specification. Compared with the prior art, the crystal material can realize high-efficiency visible band blue light, green light and near-infrared 1.3 [mu] m laser output, and has irreplaceable effects in the fields of laser biomedicine, color display, high-density storage, underwater imaging, optical communication and the like.

The invention relates to an Er and Dy co-doped lead fluoride mid-infrared laser crystal and a preparation method and application thereof, the chemical formula of the crystal is ErxDyyPb1-x-yF2, the value range of x is 0.02-0.08, and the value range of y is 0.002-0.01; the crystal grows by adopting a temperature gradient method, and the method comprises the following steps: (1) taking single crystal particles or powder of ErF3, DyF3 and PbF2 as raw materials, calculating the mass required by each raw material according to the chemical formula ErxDyyPb1-x-yF2, and accurately weighing; (2) grinding and uniformly mixing the weighed raw material powder, then putting into a porous graphite crucible, and covering with a graphite cover; and (3) placing the porous graphite crucible filled with the material in a thermal field, vacuumizing, filling protective gas, heating to ensure complete material melting and impurity removal, cooling to carry out crystal growth, cooling to room temperature after the growth is finished, and taking out the crystal. Compared with the prior art, the crystal material can realize efficient mid-infrared laser output, and can be applied to the fields of remote sensing, detection, long-distance transmission, medicine and the like.