Object Selection


Automated, miniaturized, and parallelized synthesis and testing (combinatorial chemistry/high-throughput screening) are accelerating the development of a complex of methods for data mining and computer screening (virtual screening) of object libraries. Clusters of objects are recognized (duster analysis) on the basis of the estimation of the distances in the descriptor space (dissimilarities). In the case of object selection, dasses that are as diverse as possible are selected so that all the different types of properties (e.g., bioactivities) within a larger collection are sampled using as few objects as possible (diversity analysis). Key chemical features and the spatial relationships among them that are considered to be responsible for a desired biological activity may be identified (pharmacophore recognition) using local similarity, e.g., via common substructures in sets of active molecules pharmacophore searching in 3D databases (see below) may be carried out using a pharmacophore as the query. Shape similarity of ligands to a receptor site (ligand docking) may be used for finding structures that fit into proteins.  [c.313]

AlO Wrong action on wrong object Selection SI Selection omitted  [c.215]

During the inspection of an unknown object its surface is scanned by the probe and ultrasonic spectra are acquired for many discrete points. Disbond detection is performed by the operator looking at some simple features of the acquired spectra, such as center frequency and amplitude of the highest peak in a pre-selected frequency range. This means that the operator has to perform spectrum classification based on primitive features extracted by the instrument.  [c.109]

Once the desired object is selected, a segmentation by cooccurrence matrix is engaged.  [c.233]

The procedure of testing must include measurements which have to provide reliable information about the quality of the object to be tested. The list of characteristics of measurement errors is selected on the basis of the required end results, methods of its calculation, form of presentation of the accuracy factors, reliability of the end result. These factors are of utmost attention in attestation of the procedure of testing.  [c.961]

The highest resolutions of biological samples have been possible for crystallme samples (electron crystallography). 2D crystals of membrane proteins and one cytoskeletal protein complex have been solved at the 3-4 A level combining imaging and electron diffraction, as pioneered by Flenderson and coworkers [70.71 and 72], also see figure Bl.17.11. Icosahedral virus particles are reconstructed from images to 8-9 A resolution [26,27], allowing the identification of alpha helices. Compared to single particles, these samples give much higher resolution, in part because much higher numbers of particles are averaged, but it is also possible that a crystallization process selects for the unifonnity of the crystallizing object and leads to very homogeneous ensembles.  [c.1647]

The connection table of the query object (similarity probe) is processed to obtain the set of atom pairs, and then the database file is scanned to evaluate the similarity between the query and each of the database structures. The maximum number of structures that the program will select is specified, as well as the minimum similarity score that a database compoimd must show to be selected. Within these limits, the program will select from the database the structures that are most similar (with the highest similarity value) to the query and will create an output file of compoimd numbers and similarity values, sorted by decreasing similarity, for the selected compounds.  [c.312]

The plane is specified as a plane parallel to the screen and offset from the center of mass of the current selection towards the user by a specified number of Angstroms. For example, if you make no selection and specify an offset of 0.0, the plane is through the cen-  [c.240]

You can use the semi-empirical and ab initio Orbitals dialog box in HyperChem to request a contour plot of any molecular orbital. When requested, the orbital is contoured for a plane that is parallel to the screen and which is specified by a subset selection and a plane offset, as described above. The index of the orbital and its orbital energy (in electron volts, eV) appears in the status line.  [c.244]

The edges of the joint to be welded must be prepared. The simplest joint is the square butt joint welded from one or both sides. However, such welds can only be used on thin-gauge material, since it is difficult to penetrate the joint. Various edge penetrations permit fusion across the thickness of the material. Bevel and V grooves are typically prepared by flame cutting, whereas J and U grooves require machining. The selection of single or double grooves is dictated by a variety of practical considerations. Thus, for access to only one side of a surface, a single groove is needed. Double grooves require additional preparation, but their costs are usually offset by a net reduction in weld cross-sectional area, resulting in savings in metal and welding time.  [c.348]

In the selection of an analytical technique for a specific problem the arguments brought to bear are virtually the same as in any other area of analytical chemistry information wanted, sensitivity and precision needed, matrix, etc. A very important additional consideration is the required sample size. The damage resulting from the removal of a sample for analytical study has to be weighed carefully against the benefits expected from this study. Clearly, techniques that require smaller samples are preferred. The developments in analytical techniques, with the advent of extremely sensitive instmmentation, have been of great significance. However, the same problem that accompanies all analyses of very small samples, ie, the accurate representation of the whole object by a small sample, is generally more severe in the study of antiquities. Ancient technologies generally produced materials of a much greater compositional heterogeneity than do modem industrial processes. The same holds tme for many materials used directly as they occur in nature, such as stones, clays, etc. Therefore, often the sample size is dictated not so much by the requirements of the analytical techniques available as by the nature of the material under study.  [c.418]

A Fourier-based imaging technique collects data from the / -space (2-D Fourier transform of the image) of the imaged object. Figure 3 depicts a timing diagram for a Fourier imaging sequence using simple 90-FID sequence. The timing diagram describes the appHcation of rf and three magnetic field gradients called the sHce selection (G. ), phase encoding (G ), and frequency encoding (G gradients. The first step in the Fourier imaging procedure is sHce selection of those spins in the object for which the image is to be generated. SHce selection is accompHshed by the appHcation of a magnetic field gradient at the same time the r-f pulse is appHed. A r-f pulse, having frequency width Av centered at V, excites when appHed in conjunction with a field gradient G spins centered at 2 = with a spread of spins at values Az = Av j G. Spins experiencing a magnetic field strength not satisfying the  [c.55]

Membrane Sep r tion. The separation of components ofhquid milk products can be accompHshed with semipermeable membranes by either ultrafiltration (qv) or hyperfiltration, also called reverse osmosis (qv) (30). With ultrafiltration (UF) the membrane selectively prevents the passage of large molecules such as protein. In reverse osmosis (RO) different small, low molecular weight molecules are separated. Both procedures require that pressure be maintained and that the energy needed is a cost item. The materials from which the membranes are made are similar for both processes and include cellulose acetate, poly(vinyl chloride), poly(vinyHdene diduoride), nylon, and polyamide (see AFembrane technology). Membranes are commonly used for the concentration of whey and milk for cheesemaking (31). For example, membranes with 100 and 200 p.m are used to obtain a 4 1 reduction of skimmed milk.  [c.368]

In an economic comparison of these three common abatement systems, a 1991 EPA study (58) indicates extended absorption to be the most cost-effective method for NO removal, with selective reduction only matching its performance for small-capacity plants of about 200—250 t/d. Nonselective abatement systems were indicated to be the least cost-effective method of abatement. The results of any comparison depend on the cost of capital versus variable operating costs. A low capital cost for SCR is offset by the ammonia required to remove the NO. Higher tail gas NO  [c.43]

Each type of probe used in active nondestmctive test systems has specific capabiUties and limitations. The probe type, ie, a coil, slender probe, flat transducer, etc, affects the response from the discontinuity or feature to be evaluated. Eor example, surface, near-surface, surface-connected, interior, back-surface, flat surface, curved surface, rough or smooth surface anomaUes and discontinuities such as cracks, porosity, inclusions, lamination, segregation, leaks, bonding, corrosion pinholes or attack, erosion, wall thinning, missing components, etc, all can be detected using NDE. No single type of inspection method, however, is adequate to detect all of the material conditions and discontinuities that can influence the serviceabiUty of materials or systems. Thus, for rehable testing, two or more basically different types of test methods are usually necessary to detect and confirm conditions that may affect performance. Different materials or test-object geometries may require totally different tests or combinations of tests to ensure reflabiUty. In many cases, the test methods appropriate for materials identification and selection prior to processing or welding are quire different from those that should be used after manufacture, erection, or during maintenance shutdown periods of faciUties. In particular, the test method should be selected with consideration of materials, shapes, accessibiUty, and conditions or defects that affect the integrity and serviceabiUty of the material, component, stmcture, or system to be tested.  [c.124]

The first step in creating a printing image is usually to contact the surface of the radiation-sensitive coating of the printing plate with a photographic film positive or negative, and to expose it to a light source emitting between 380 and 420 nm, the spectral region to which most commercial offset plates are sensitized. So as to obtain acceptable image definition, the plate surface and overlying film must be in intimate contact during the exposure stage. This is best achieved by the use of a vacuum printing frame. For particularly rapid drawdown, ie, evacuation of ak, a matte layer is appHed to the surface of the radiation-sensitive coating. The next step is to treat the imagewise exposed plate with a specially designed aqueous or organic solvent-based developer solution in order to remove selectively the now comparatively more soluble portions of the coating, thus revealing the support surface in the underlying areas.  [c.43]

In contrast, various sensors are expected to respond in a predictable and controlled manner to such diverse parameters as temperature, pressure, velocity or acceleration of an object, intensity or wavelength of light or sound, rate of flow, density, viscosity, elasticity, and, perhaps most problematic, the concentration of any of millions of different chemical species. Furthermore, a sensor that responds selectively to only a single one of these parameters is often the goal, but the first attempt typically produces a device that responds to several of the other parameters as well. Interferences are the bane of sensors, which are often expected to function under, and be immune to, extremely difficult environmental conditions.  [c.389]

Then three prints ate appHed by offset gravure printing using three carefliUy selected color inks. The panel is assembled into the furniture and finished with lacquers as in the standard process.  [c.357]

Elements that can dissolve in copper, such as zinc, tin, and nickel for example, increase annealed strength by varying amounts depending on the element and the quantity in solution. The effect of selected solution hardening elements on tensile properties of annealed copper aUoys is iUustrated by the data in Table 4, where the yield strength is the stress at 0.2% offset strain in a tensile test.  [c.219]

The cleaning of a solid object, ie, the removal of unwanted foreign matter from its surface, is done by methods ranging from simple mechanical separation such as blotting or abrasion to removal by solution or selective chemical action. The term detergency is limited to systems in which a Hquid bath is present and is the main cleaning component of the system. The action of the bath involves more than simple solution or simple hydraulic dislodging of soil, although both will occur and contribute to the cleaning. The cleaning is enhanced primarily by the presence in the bath of a special solute, the surfactant, which alters interfacial effects at the various phase boundaries within the system. Thus, a typical detersive system consists of a soHd object to be cleaned, called the substrate soil or dirt attached to it which is to be removed in the washing process and a Hquid bath that is appHed to the soiled substrate. In turn, each of these elements can vary widely in properties and composition. The final cleaning benefit results from interaction of these elements and the conditions used, ie, temperature, time, mechanical energy input (agitation) and, in the case of aqueous baths, the presence of hardness ions in the water.  [c.526]

The words system and surroundings are similarly coupled. A system is taken to be any object, any quantity of matter, any region, and so on, selected for study and set apart (mentally) from everything else, which is called the surroundings. The imaginary envelope which encloses the system and separates it from its surroundings is called the boundary of the system.  [c.513]

Heat Transfer This is the most important single factor in evaporator design, since the heating surface represents the largest part of evaporator cost. Other things being equal, the type of evaporator selected is the one having the highest heat-transfer cost coefficient under desired operating conditions in terms of J/s K (British thermal units per hour per degree Fahrenheit) per dollar of installed cost. When power is required to induce circulation past the heating surface, the coefficient must be even higher to offset the cost of power for circulation.  [c.1137]

In selecting the boiling temperature, consideration must be given to the effect of temperature on heat-transfer characteristics of the type of evaporator to be used. Some evaporators show a marked drop in coefficient at low temperature—more than enough to offset any gain in available temperature difference. The condenser cooling-water temperature and cost must also be considered.  [c.1145]

Cost Data for Spray Dryers Drying chambers, ductwork, and cyclone separators are usually constructed of stainless steel. Savings of roughly 20 percent may be achieved on the total purchase cost by using carbon steel the increasing tendency toward the use of heat-resistant and corrosion-resistant plastic coatings (epoxy resins) makes the future appear promising for greater use of carbon steel construction. Wide differences in cost may be experienced in the selection of basic equipment. Air heaters vary in price range according to the selection of steam, electricity, direcl-fired, and indirect-fired oil or gas heaters. Dust-collection equipment may consist of cyclone collectors or bag-type filters and may include a wet scrubber. Costs of nozzle and centrifugal atomizers are usually comparable. While the centrifugal atomizer requires mechanical gearing and motor drive, a high-pressure nozzle requires a high-pressure pump, which will usu ly more than offset the cost of gearing and motor for the centrifug atomizer. Auxihary equipment which may be included comprises air filters, diying-chamber insulation, and mechanical or pneumatic cooling conveyors. A minimum of instrumentation consists of indicating and recording thermometers for inlet-air and outlet temperatures, an ammeter for atomizer motor drive (or a pressure gauge for nozzle atomization), a flowmeter, manometers, a high-temperature alarm, and a panelboard with push-button stations for aU equipment. The diying process may be completely controlled automatically with some additional instrumentation.  [c.1238]

From this table the most efficient unit can be selected and balanced against price. It is apparent that for 300 hp the 28-in diameter achieves no gain over the 22-in diameter because of the increase in horsepower loss. For 22 in versus 18 in the gain is small and may be offset by the higher price.  [c.2498]

I Shunt reactors These are provided as shown in Figure 24.23 to compensate for the distributed lumped capacitances, C , on EHV networks and also to limit temporary overvoltages caused during a load rejection, followed by a ground fault or a phase fault within the prescribed steady-state voltage limits, as noted in Table 24.3. They ab.sorb reactive power to offset the charging power demand of EHV lines (Table 24.2, column 9). The selection of a reactor can be made on the basis of the duty it has to perform and the compensation required. Some of the different types of reactors and their characteristics are described in Chapter 27.  [c.798]

In the process of X-raying the computer forms a data base, using video-images of tested objects and besides using a special algorithm, it can control an operation mode of all functional units of XTVI. A specific program switches on a TV camera and sets parameters of X-raying and an X-ray unit operation mode. The most informative frame is selected and written on a computer disk. Both a tested object or an X-raying area are moved with an automated positioning unit.  [c.450]

Figure Al.6.26. Stereoscopic view of ground- and excited-state potential energy surfaces for a model collinear ABC system with the masses of HHD. The ground-state surface has a minimum, corresponding to the stable ABC molecule. This minimum is separated by saddle points from two distmct exit chaimels, one leading to AB + C the other to A + BC. The object is to use optical excitation and stimulated emission between the two surfaces to steer the wavepacket selectively out of one of the exit chaimels (reprinted from [54]). Figure Al.6.26. Stereoscopic view of ground- and excited-state potential energy surfaces for a model collinear ABC system with the masses of HHD. The ground-state surface has a minimum, corresponding to the stable ABC molecule. This minimum is separated by saddle points from two distmct exit chaimels, one leading to AB + C the other to A + BC. The object is to use optical excitation and stimulated emission between the two surfaces to steer the wavepacket selectively out of one of the exit chaimels (reprinted from [54]).
Molecular chirality is of extraordinary importance in many different fields because it often has dramatic consequences in observable molecular properties. For example, two molecules that arc mirror images of each other (enantiomers) often have different pharmacological activity, odor, environmental impact, chemical reactivity (when another chiral object i.s pre.sent), or physical properties (e.g., CD spectra). Chirality is a major point in drug safety evaluation, and an increasing percentage of drugs arc marketed as single enantiomers. This requires synthesis methodologies for preparing one enantiomer selectively (cnantioselectivc synthesis), as well as analytical methods to separate, quantify, and identify opposite enantiomers (c.g., chiral chromatography).  [c.77]

The plane is specified as a plane parallel to the screen and offset from the center of mass of the current selection towards the user by a specified n u m her of An gsLroin s. Tor exam pie, if you m ahe n o selection and specify an offset of 0.0, th e plan e is th rough thecen-  [c.240]

You can use Lhe senii-empineal an tl ab initio Orbuals dialog box in IlyperChem Lo ret iies[ a con Lour ploL of any molecular orbital. When req nested, lhe orbital is con toured for a plane that is parallel lo lhe screen and which is specified by a subset selection and a plane offset, as described above. The index of the orbilal and its orbilal energy (in electron volts, eV) appears in the stains line.  [c.244]

Inks. Web offset inks are highly pigmented, to yield the desired print density at a thin printing film (- 1 //m). The viscosity of offset inks is relatively high, but varies with the press configuration. For example, low and high shear viscosities are the highest for open fountain inks, and lower for injector and keyless inks. The flow characteristics for these inks are in reversed order thus keyless inks possess the most flow whereas open fountain inks the least. Inks of two distinct chemistries are used in this process a traditional type based on mineral oil, and a newer one containing soya bean oil. The resins employed are selected from low cost nonfunctional hydrocarbon-type resins, more complex hydrocarbon resins (qv) modified with rosin and/or phenoHcs, and gHsonite (for black only).  [c.249]

The same four operating steps are used with the complex batch reactor as with the simple batch reactor. The powerhil capabiUties of the complex batch reactor offset their relatively high capital cost. These reactors can operate at phenol to alkene mole ratios from 0.3 to 1 and up. This abiUty is achieved by designing for positive pressure operation, typically 200 to 2000 kPa (30 to 300 psig), and for the use of highly selective catalysts. Because these reactors can operate at low phenol to alkene mole ratios, they are ideal for production of di- and trialkylphenols.  [c.63]

Some limited economic data are also available for certain of the industrial apphcations that are critically dependent on release agents. The pressure-sensitive tape industry is an example. This apphcation is dominated by sihcones, and in the United States in 1982 sihcones valued at an estimated 75 X 10 were used for paper coatings for this industry. This estimate is consistent with a later 1988 estimate for worldwide sales of sihcone release agents of ah. types of 130 150 x 10 (26). Growth is limited in many of these release apphcations, with price increases largely offset by production efficiencies. Adhesives volume has only grown overall since the mid-1980s at a 2% aimual rate (27), and it is likely that the related abhesive apphcation has grown similarly. Release agent product prices vary from - 2 to > 80/kg (3), depending on the type and concentration of active constituent. The lower cost products are simple solvent dispersions of stearates and paraffin waxes. The more expensive products are complex, catalyzed reactive proprietary compositions. They may sometimes be the only alternative, but they are often cost effective even when less expensive materials can be used, because of the lower amount generally required or their multiple-release usabhity. A release agent should be selected not on the basis of unit cost, but for its impact on overall processing and finishing costs.  [c.102]

Manufacture of Benzene. Toluene is converted to benzene by hydrodemethylation either under thermal or catalytic conditions. Benzene produced from this source generally suppHes 25—30% of the total benzene demand. Reaction conditions generally range from 600—800°C at 3.55—7.00 MPa (500—1000 psi), and the reaction is exothermic. Conversion per pass is 60—90% with selectivities to benzene >95%. With catalysts, typically supported Cr202, M02O2, and CoO, operating temperatures are lower than in the thermal process and selectivities are higher. These gains, however, are offset by the need to decoke the catalyst periodically. Losses to by-product formation, particularly biphenyls, are controlled by recycle of these materials to the reaction zone (50,51). A flow scheme for a typical catalytic process (51) is shown in Figure 12.  [c.188]

Nowadays in the light of finding the ways of solution of ecological problems, with the improvements in standards of micro quantity definition of metals in new materials, with the intensification in food products and water quality standards the problem of limits of micro quantity determination of metals and the accuracy of the definition methods becomes important. Lead, cadmium and chromium are super toxicants and their concentration in waste, waters, air, soil and food products has to be controlled. One of the basic methods of these elements definition in objects of complex chemical composition is the atomic absorption spectrometry. At present customary water solutions become inferior to other mediums. Aqua-organic and non-aqueous solutions have been used for a long period of time currently the use of ultra decisive fluids, ionic liquids and so-called organized mediums such as aqua micellar surfactant solutions is more common. Therefore the object of presented work is the sensibility and selectivity intensification of lead, cadmium and chromium atomic absorption determination as well as the establishment of possibility of air-acetylene flame-low-temperature flame (propane-butane-air) transition. The systematic research of surfactants (kation, anion, non-ion) nature and concentration influence on analytical signal in atomic absolution determination of lead, cadmium and chromium has been successfully conducted on models. The established results have been compared. The mixtures of modifiers that maximize the analytical signal have been sorted. The surfactant-based modifier addition to analyzed solutions reduces viscosity, surface stretching and the drop size of sprayed solution, boosts the effectiveness of spraying and transforms oxidation-reduction eminence of flame. The ion redistribution of defined components takes place, which leads to their saturation primarily in small size drops. The sensibility of metals atomic absolution determination increases in 2 or 3 times. Mineral acids and other attendant components influence on lead, cadmium and chromium analytical signal during their atomic absolution determination in low-temperature flame has been studied. The modifier addition to analyzed solutions intensifies selectivity of atomic absolution determination. The modifier-based methodology of cadmium and chromium atomic absolution determination in food products, of chromium in sewage waters. The detection limit has been evaluated.  [c.160]

The development of highly selective chemical sensors for complex matrixes of medical, environmental, and industrial interest has been the object of greate research efforts in the last years. Recently, the use of artificial materials - molecularly imprinted polymers (MIPs) - with high recognition properties has been proposed for designing biomimetic sensors, but only a few sensor applications of MIPs based on electrosynythesized conductive polymers (MIEPs) have been reported [1-3].  [c.322]

The use of intermolecular minimum interaction energies and distances between the model compounds and water makes the assignment of convergence criteria for the partial atomic charges straightforward. Typically, the energetic average difference (average over all interaction energy pairs) should be less than 0.1 kcal/mol and the rms difference should be less than 0.5 kcal/mol. The small value of the average difference is important because it ensures that the overall solvation of the molecule will be reasonable, while the rms criterion of 0.5 kcal/mol ensures that no individual term is too far off the target data. Emphasis should be placed on accurately reproducing the more favorable interactions, which are expected to be the more important in MD or MC simulations, at the expense of the less favorable interactions. With distances, the rms difference should be less than 0.1 A note that the l/r - repulsive wall leads to the differences generally being larger than the QM values, especially in the analysis of data from MD simulations. For both energies and differences, the criteria presented above are with respect to the target data after they have been offset and scaled (see above). In the case of small-molecule dimers (e.g., Watson-Crick basepairs), the difficulty is again in selection of the appropriate target data, as with the confonnational energetics discussed in the preceding paragraph, rather than the degree of convergence. Again, suitable experimental or QM data must be identified and then the empirical parameters must be optimized to reproduce both sets of data as closely as possible. If problems appear during application of the parameters, then the target data themselves must be reassessed and the parameters reoptimized as necessary.  [c.33]


See pages that mention the term Object Selection : [c.220]    [c.310]    [c.450]    [c.580]    [c.1521]    [c.2106]    [c.81]    [c.241]    [c.241]    [c.166]    [c.31]   
See chapters in:

Chemoinformatics  -> Object Selection

Chemoinformatics  -> Object Selection