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  • Articles  (44,483)
  • Springer  (44,483)
  • 1990-1994  (23,025)
  • 1985-1989  (18,516)
  • 1950-1954  (2,942)
  • Geosciences  (42,017)
  • Architecture, Civil Engineering, Surveying  (6,290)
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  • Articles  (44,483)
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  • 1
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    Springer
    Stochastic environmental research and risk assessment 8 (1994), S. 157-172 
    ISSN: 1436-3259
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract Operator representations of stochastic subsurface flow equations allow writing their solutions implicitly or explicitly in terms of integro-differential expressions. Most of these representations involve Neumann series that must be truncated or otherwise approximated to become operational. It is often claimed that truncated Neumann series allow solving groundwater flow problems in the presence of arbitrarily large heterogeneities. Such claims have so far not been backed by convincing computational examples, and we present an analysis which suggests that they may not be justified on theoretical grounds. We describe an alternative operator representation due to Neuman and Orr (1993) which avoids the use of Neumann series yet accomplishes a similar purpose. It leads to a compact integro-differential form which provides considerable new insight into the nature of the solution. When written in terms of conditional moments, our new representation contains local and nonlocal effective parameters that depend on scale and information. As such, these parameters are not unique material properties but may change as more is learned about the flow system.
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  • 2
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    Stochastic environmental research and risk assessment 8 (1994), S. 185-205 
    ISSN: 1436-3259
    Keywords: Contaminant transport ; adsorption ; decay ; random walk ; killing ; Kolmogorov equations ; contamination of a well
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract This study deals with the transport of a contaminant in groundwater. The contaminant is subject to first order decay or linear adsorption. Its displacement can be modeled by a random walk process in which particles are killed at exponentially distributed times. Dirichlet problems are derived for the rate and mean time at which contaminated particles reach a particular part of the boundary of a certain domain. These Dirichlet problems are solved asymptotically for two types of 2D-flow patterns: flow parallel to the boundary of a domain and arbitrary flow towards a well in an aquifer.
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  • 3
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    Stochastic environmental research and risk assessment 8 (1994), S. 109-116 
    ISSN: 1436-3259
    Keywords: Unsaturated ; nonlocal ; memory ; statistical physics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract As illustrated variously by wetting and drying scanning curves, flow in unsaturated porous media is inherently nonlocal. This nonlocality is also manifest in hysteresis in the classical Darcy conductivity. It is the authors' belief that most current theories of unsaturated/saturated flow are often inadequate, as they do not account for spatial nonlocality and memory. Here we provide a fundamental theory in which nonlocality of the flow constitutive theory is a natural consequence of force balances. The results are derived from general principles in statistical physics and under appropriate limiting conditions, the classical Darcy's Law is recovered for saturated flow. A notable departure in this theory from other nonlocal flow theories is that a classical Darcy type equation on a small scale need not exist.
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  • 4
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    Stochastic environmental research and risk assessment 8 (1994), S. 139-155 
    ISSN: 1436-3259
    Keywords: Porous media ; random media ; random fields ; groundwater flow ; stochastic hydrology ; stochastic partial differential equations ; perturbation methods ; Taylor expansions ; hierarchical systems ; Green's functions ; effective conductivity ; homogenization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract This paper investigates analytical solutions of stochastic Darcy flow in randomly heterogeneous porous media. We focus on infinite series solutions of the steady-state equations in the case of continuous porous media whose saturated log-conductivity (lnK) is a gaussian random field. The standard deviation of lnK is denoted ‘σ’. The solution method is based on a Taylor series expansion in terms of parameter σ, around the value σ=0, of the hydraulic head (H) and gradient (J). The head solution H is expressed, for any spatial dimension, as an infinite hierarchy of Green's function integrals, and the hydraulic gradient J is given by a linear first-order recursion involving a stochastic integral operator. The convergence of the ‘σ-expansion’ solution is not guaranteed a priori. In one dimension, however, we prove convergence by solving explicitly the hierarchical sequence of equations to all orders. An ‘infinite-order stochastic solution is obtained in the form of a σ-power series that converges for any finite value of σ. It is pointed out that other expansion methods based on K rather than lnK yield divergent series. The infinite-order solution depends on the integration method and the boundary conditions imposed on individual order equations. The most flexible and general method is that based on Laplacian Green's functions and boundary integrals. Imposing zero head conditions for all orders greater than one yields meaningful far-field gradient conditions. The whole approach can serve as a basis for treatment of higher-dimensional problems.
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  • 5
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    Stochastic environmental research and risk assessment 8 (1994), S. 173-183 
    ISSN: 1436-3259
    Keywords: Probability weighted moment ; scaling in rainfall ; stable distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract We present a statistically robust approach based on probability weighted moments to assess the presence of simple scaling in geophysical processes. The proposed approach is different from current approaches which rely on estimation of high order moments. High order moments of simple scaling processes (distributions) may not have theoretically defined values and consequently, their empirical estimates are highly variable and do not converge with increasing sample size. They are, therefore, not an appropriate tool for inference. On the other hand we show that the probability weighted moments of such processes (distributions) do exist and, hence, their empirical estimates are more robust. These moments, therefore, provide an appropriate tool for inferring the presence of scaling. We illustrate this using simulated Levystable processes and then draw inference on the nature of scaling in fluctuations of a spatial rainfall process.
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  • 6
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    Stochastic environmental research and risk assessment 8 (1994), S. 156-156 
    ISSN: 1436-3259
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
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  • 7
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    Stochastic environmental research and risk assessment 8 (1994), S. 19-55 
    ISSN: 1436-3259
    Keywords: Indicator kriging ; stochastic simulation ; soft data ; Walker Lake ; sequential simulation ; scaling-up
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract A Monte Carlo approach is described for the quantification of uncertainty on travel time estimates. A real (non synthetic) and exhaustive data set of natural genesis is used for reference. Using an approach based on binary indicators, constraint interval data are easily accommodated in the modeling process. It is shown how the incorporation of imprecise data can reduce drastically the uncertainty in the estimates. It is also shown that unrealistic results are obtained when a deterministic modeling is carried out using a kriging estimate of the transmissivity field. Problems related with using sequential indicator simulation for the generation of fields incorporating constraint interval data are discussed. The final results consists of 95% probability intervals of arrival times at selected control planes reflecting the original uncertainty on the transmissivity maps.
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  • 8
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    Stochastic environmental research and risk assessment 8 (1994), S. 79-108 
    ISSN: 1436-3259
    Keywords: Stochastic flow equations ; conditional simulation ; spectral representations ; joint conditioning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract The use of data to condition single random fields has a well-established history. However, the joint use of data from several cross-correlated random fields is not as well developed. For example, the use of both transmissivity and head data in a steady state 2-d stochastic flow problem is essentially an inverse problem that is very important for both flow and transport predictions. This problem is addressed here by using a combination of numerical simulation and analytical methods and its application illustrated. The type of information conveyed by the different data categories is explored. The results presented are especially interesting in that head and transmissivity each give different information: Head values would appear to constrain the geometry of the paths while transmissivity data yields information about travel times. The linearized model is expanded to an iterative procedure and the “true” conditional distribution at several locations is compared with the iterative solution. The problem mentioned above is one with a special transfer function specified by the flow equation. In the second part of the paper a Fast Fourier Transform method for generation and conditioning of two or more random fields is introduced. This procedure is simple to implement, fast and very flexible.
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  • 9
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    Stochastic environmental research and risk assessment 8 (1994), S. 1-17 
    ISSN: 1436-3259
    Keywords: Stochastic diffusion equations ; effective hydraulic conductivity ; correlation scale ; heterogeneous aquifers ; spectral representation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract Assuming that the ln hydraulic conductivity in an aquifer is mathematically approximated by a spatial deterministic “surface”, or trend, plus a stationary random noise, we treat the problem of finding what the effective hydraulic conductivity of that aquifer is. This problem is tackled by spectral methods applied to a type of diffusion equation of groundwater flow, together with suitable coordinate transformations. Analytical (exact) solutions in terms of elementary functions are presented for one- and three-dimensional finite and infinite domains. Stability criteria are obtained for the solutions, in terms of a critical parameter, that turns out to involve the product of correlation scale and trend gradient. For the case of finite and symmetrical domains, additional provisions to insure the stability of numerical calculations of effective hydraulic conductivity are provided. Effective hydraulic conductivity is an important property, with potential applications in the calibrations of groundwater and transport numerical models.
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  • 10
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    Stochastic environmental research and risk assessment 8 (1994), S. 219-231 
    ISSN: 1436-3259
    Keywords: Parameter estimation ; flood frequency analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract A mixed method combining the method of moments and the method of optimization (MMO) was developed for estimating the parameters of the log-Pearson type 3 (LP3) distribution. The MMO estimates the parameters of mean and standard deviation by the method of indirect moments (MIM) and estimates the coefficient of skewness by minimizing both the relative root average square error (RRASE) and the relative average bias (RAB). Both the predictive capability and descriptive capability of six popular estimation methods were evaluated using 90 sets of observed flood data and six selected LP3 populations with 1000 samples for each selected sample size. The performance of the MMO was compared with those of five other selected estimation methods. A weighted ranking index (WRI) procedure was developed to help select the best combination of distribution and method for the Louisiana flood data. The WRI takes both the predictive capability and the descriptive capability into account in the evaluation. The combination of LP3/MMO was found to be the best combination for Louisiana flood data.
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  • 11
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    Stochastic environmental research and risk assessment 8 (1994), S. 281-300 
    ISSN: 1436-3259
    Keywords: Stochastic analysis ; unsaturated flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract In this article, we are concerned with the statistics of steady unsaturated flow in soils with a fractal hydraulic conductivity distribution. It is assumed that the spatial distribution of log hydraulic conductivity can be described as an isotropic stochastic fractal process. The impact of the fractal dimension of this process, the soil pore-size distribution parameter, and the characteristic length scale on the variances of tension head and the effective conductivity is investigated. Results are obtained for one-dimensional and three-dimensional flows. Our results indicate that the tension head variance is scale-dependent for fractal distribution of hydraulic conductivity. Both tension head variance and effective hydraulic conductivity depend strongly on the fractal dimension. The soil pore-size distribution parameter is important in reducing the variability of the unsaturated hydraulic conductivity and of the fluxes.
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  • 12
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    Stochastic environmental research and risk assessment 8 (1994), S. 301-317 
    ISSN: 1436-3259
    Keywords: Change ; discontinued stations ; entropy ; networks ; optimization ; prediction ; unbiased ; water quality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract A new methodology for predicting water quality values at discontinued water quality monitoring stations is proposed. The method is based upon the Principle of Maximum Entropy (POME) and provides unbiased predictions of water quality levels at upstream tributaries and on the mainstem of a river given observed changes in the distribution of the same water quality parameter at a downstream location. Changes in the values of water quality parameters which are known a priori to have occurred upstream, but which are not sufficiently large to account for all the observed change in the same water quality parameter at the downstream location are able to be incorporated in the method through the introduction of a new term in the basic entropy expression. Application of the procedure to water quality monitoring on the Mackenzie River in Queensland, Australia indicates the method has considerable potential for prediction of water quality at discontinued stations. The method also has potential for identifying the location of causes of observed changes in water quality at a downstream station.
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  • 13
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    Stochastic environmental research and risk assessment 8 (1994), S. 233-258 
    ISSN: 1436-3259
    Keywords: Flood ; China ; river ; sampling variance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract The sampling variance of a T-year flood when estimated using a curve-fitting method results from the errors in hydrologic observations, plotting positions, and model-fitting. This paper develops a method to quantify the contribution of plotting positions to the sampling variance of the T-year flood magnitude. Application of the method to 150 flood-flow data sets of 41 rivers in the People's Republic of China show that the errors due to plotting positions contribute more to the sampling variance than others.
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  • 14
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    Stochastic environmental research and risk assessment 8 (1994), S. 269-280 
    ISSN: 1436-3259
    Keywords: Unit hydrograph ; least square methods ; regression analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract This paper discusses the derivation of a unit hydrograph by multiple storm analysis using least squares methods. Variations of least squares method was generalized using the framework of weighted ridge analysis. The paper also shows two theorems to support using multi-storm analysis to derive UH. In addition, an issue was addressed on the scaling effect in the conventional multi-storm analysis which could create potential bias toward large storms in deriving a multi-storm UH. For that, a simple scaling procedure was proposed to reduce such potential bias problem. Numerical investigations were conducted to examine the performance of the scaling procedure by comparing with the conventional multi-storm analysis (without scaling) and the HEC-1 weighing procedures. Based on various performance criteria using a total of 39 storms from three watersheds, the proposed scaling procedure was found to produce a quite desirable UH.
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  • 15
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    Stochastic environmental research and risk assessment 8 (1994), S. 57-77 
    ISSN: 1436-3259
    Keywords: Stochastic transport ; risk assessment ; concentration CDF ; exceedance probabilities
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract This paper presents the principles underlying a recently developed numerical technique for modeling transport in heterogeneous porous media. The method is then applied to derive the concentration mean and variance, the concentration CDF, exceedance probabilities and exposure time CDF, which are required by various regulatory agencies for risk and performance assessment calculations. The dependence of the various statistics on elapsed travel time, location in space, the dimension of the detection volume, natural variability and pore-scale dispersion is investigated and discussed.
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  • 16
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    Stochastic environmental research and risk assessment 8 (1994), S. 117-138 
    ISSN: 1436-3259
    Keywords: Stochastic hydrology ; random fields ; space transformations ; generalized functions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract In earlier publications, certain applications of space transformation operators in subsurface hydrology were considered. These operators reduce the original multi-dimensional problem to the one-dimensional space, and can be used to study stochastic partial differential equations governing groundwater flow and solute transport processes. In the present work we discuss developments in the theoretical formulation of flow models with space-dependent coefficients in terms of space transformations. The formulation is based on stochastic Radon operator representations of generalized functions. A generalized spectral decomposition of the flow parameters is introduced, which leads to analytically tractable expressions of the space transformed flow equation. A Plancherel representation of the space transformation product of the head potential and the log-conductivity is also obtained. A test problem is first considered in detail and the solutions obtained by means of the proposed approach are compared with the exact solutions obtained by standard partial differential equation methods. Then, solutions of three-dimensional groundwater flow are derived starting from solutions of a one-dimensional model along various directions in space. A step-by-step numerical formulation of the approach to the flow problem is also discussed, which is useful for practical applications. Finally, the space transformation solutions are compared with local solutions obtained by means of series expansions of the log-conductivity gradient.
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  • 17
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    Stochastic environmental research and risk assessment 8 (1994), S. 207-218 
    ISSN: 1436-3259
    Keywords: Partial duration ; Weibull ; nonhomogeneity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract Simple homogeneous formulations of two extreme value partial duration flood models are compared to more sophisticated compound formulations in terms of asymptotic performance of quantile estimates. The compound model formulations were developed to model flood series resulting from mixed climatological processes. It was found that only in the case of marked nonhomogeneity in the data samples did the compound formulation of the models offer significant advantages in terms of variance of quantile estimates. However, the estimates from the homogeneous model were significantly biased in the negative direction. This negative bias of quantile estimates from the simple model was even more pronounced when the more sophisticated Weibull model was used as the base.
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  • 18
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    Stochastic environmental research and risk assessment 8 (1994), S. 259-268 
    ISSN: 1436-3259
    Keywords: Rainfall ; runoff ; modeling ; uncertainty ; stochastics ; stochastic integral equations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract In this paper a very general rainfall-runoff model structure (described below) is shown to reduce to a unit hydrograph model structure. For the general model, a multi-linear unit hydrograph approach is used to develop subarea runoff, and is coupled to a multi-linear channel flow routing method to develop a link-node rainfall-runoff model network. The spatial and temporal rainfall distribution over the catchment is probabilistically related to a known rainfall data source located in the catchment in order to account for the stochastic nature of rainfall with respect to the rain gauge measured data. The resulting link node model structure is a series of stochastic integral equations, one equation for each subarea. A cumulative stochastic integral equation is developed as a sum of the above series, and includes the complete spatial and temporal variabilities of the rainfall over the catchment. The resulting stochastic integral equation is seen to be an extension of the well-known single area unit hydrograph method, except that the model output of a runoff hydrograph is a distribution of outcomes (or realizations) when applied to problems involving prediction of storm runoff; that is, the model output is a set of probable runoff hydrographs, each outcome being the results of calibration to a known storm event.
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  • 19
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    Stochastic environmental research and risk assessment 8 (1994), S. 318-318 
    ISSN: 1436-3259
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
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  • 20
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    Fire technology 30 (1994), S. 97-97 
    ISSN: 1572-8099
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying
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  • 21
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    Fire technology 30 (1994), S. 173-178 
    ISSN: 1572-8099
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  • 22
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    Fire technology 30 (1994), S. 134-154 
    ISSN: 1572-8099
    Keywords: Fire hazards ; tunnel ; multi-zone ; smoke movement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying
    Notes: Abstract A computer model that simulates fire growth movement in tunnels is described, and a brief overview of tunnel systems is presented. The methods for predicting mass flows, velocities, smoke concentrations, and heat transfer are presented, along with a list of hazard output parameters. The validation of the model against experiment, and possible directions for future work are also presented.
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  • 23
    ISSN: 1572-8099
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    Topics: Architecture, Civil Engineering, Surveying
    Notes: Abstract In early 1991, a new sprinkler system was planned for the existing National Archives/National Library of Canada building in Ottawa. A major challenge in the design and installation of the sprinkler systems was to protect mobile compact shelving units located in the three levels below grade. Storage of documents in these shelving units is typically within 178 mm of the concrete slab ceiling. The minimum clearance permitted by the sprinkler system installation standard is 457 mm from the sprinkler deflector to the top of the storage. To conform with the sprinkler design standard, the top level or levels of storage would have had to be removed and additional storage space acquired. Because of the annual cost of this additional storage, an investigation was begun to determine feasible alternatives that would permit a reduction in clearances between sprinklers and storage, while maintaining an acceptable level of fire safety. This paper describes the series of five full-scale fire tests that were conducted to assess various fire protection options. Based on these tests, design criteria were developed for a sprinkler system using quick response horizontal sidewall sprinklers to protect the mobile shelving units. An overview of this technically based fire protection system for use in protecting shelving units with reduced clearance is also presented.
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  • 24
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    Fire technology 30 (1994), S. 458-467 
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  • 25
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    Fire technology 30 (1994), S. 478-479 
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  • 26
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    Fire technology 30 (1994), S. 468-477 
    ISSN: 1572-8099
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying
    Notes: Abstract In this article, we explain cost-benefit terms and how they apply to fire safety, then summarize the findings of several social fire safety cost-benefit analyses we have done in Sweden. We have found that smoke detectors and portable fire extinguishers are useful in the average single-family home, but sprinklers are not. Sprinkler systems are very helpful in the average manufacturing industry but too expensive. In most chemical plants, however, they are profitable. Sprinklers in the average hotel have higher costs than expected benefits and therefore are not profitable. In health-care facilities, particularly psychiatric wards, they are profitable. Our research also shows that chimney sweeping is carried out too frequently in Sweden and that in new residential areas, water from tanker vehicles is more effective against fires than water from hydrants.
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  • 27
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    Fire technology 30 (1994), S. 338-340 
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  • 28
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    Fire technology 30 (1994), S. 326-337 
    ISSN: 1572-8099
    Keywords: Detection ; fire detection ; probability ; fire research
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying
    Notes: Abstract This report is a formal, functional analysis of fire detection systems' requirements. The performance parameters of fire detection systems are given as conditional probabilities. These parameters are identified by the objective analysis of the functions of a fire detection system. It is demonstrated that using the false alarm rate to specify the malfunctioning of a thresh-old-detection system is inadequate. The principal function of fire detection systems is identified as the notification of antifire agents of the probability of an unwanted fire. The evaluation of the information provided by a detector system is central to its worth.
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  • 29
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    Fire technology 30 (1994), S. 357-365 
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    Topics: Architecture, Civil Engineering, Surveying
    Notes: Abstract The FORUM for International Cooperation on Fire Research is an informal group of people committed to fire research and the application of fire-research results. Since it was formed in 1988, the FORUM has brought together organizational leaders who direct resources for fire research throughout the world. This article is reprinted from the Nordic Fire Safety Engineering Symposium, Development and Verification of Tools for Performance Codes, August 30–September 1, 1993, in Espoo, Finland.
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  • 30
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    Fire technology 30 (1994), S. 374-375 
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  • 31
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    Fire technology 30 (1994), S. 179-182 
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  • 32
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    Fire technology 30 (1994), S. 183-185 
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  • 33
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    Fire technology 30 (1994), S. 193-194 
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  • 34
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    Fire technology 30 (1994), S. 186-190 
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  • 35
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    Fire technology 30 (1994), S. 195-208 
    ISSN: 1572-8099
    Keywords: Plate thermometer ; fire resistance ; furnace ; thermocouple
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying
    Notes: Abstract The measured fire resistance of a structure tested in different furnaces in accordance with ISO 834 may differ considerably. Similarly, the fire resistance of that same structure may be 25% longer when tested in accordance with ISO than it is when tested in accordance with ASTM. These anomalies complicate the evaluation of test results and must be eliminated to reach harmonized international testing. The heat transfer to a test specimen in a test furnace at high temperature depends primarily on radiant flux rather than convection. Temperature measurement devices used to control furnaces should therefore respond to this type of heating in a way similar to that in which test specimens respond. They should have a large area so that the radiant heat transfer dominates, and they must, at the same time, have a quick thermal response. The plate thermometer is designed to have these properties. It consists of a thin steel plate, 100 mm by 100 mm and 0.7 mm thick, with an insulating fiber board on one side. A thermocouple is welded to the center of the plate. It should be placed in front of the specimen, with the insulated side facing the specimen. The exposed side will then receive the same radiant heat flux as the specimen. This paper describes the plate thermometer and gives a basic theoretical analysis of the heat transfer conditions in furnaces. Measurements with the plate thermometer in several furnaces are also reported.
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    Fire technology 30 (1994), S. 209-231 
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    Notes: Abstract Dimensional analysis is used to examine heat transfer from flames to vertical surfaces. Configurations include a line fire against a wall, a square burner flame against a wall and in a corner, and window flames impinging on a wall. Dimensionless parameters that affect flame heat flux includeϰ/l f ,y/D,l f /D andkD whereϰ is vertical distance,y is horizontal distance,l f is flame length,D is burner dimension, andk is the flame absorption coefficient. Only the effect of these variables is shown. No general correlation is developed, and more data are needed before these results can be applied with confidence.
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    Fire technology 30 (1994), S. 155-172 
    ISSN: 1572-8099
    Keywords: Airborne sampling ; field tests ; fire research ; fires ; measurement ; measuring instruments ; oils ; particulates ; pool fires ; sampling ; smoke ; smoke yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying
    Notes: Abstract A unique airborne smoke sample package (ASSP) for determining the smoke yield of large fires has been developed. The uncertainty in the average smoke yield at the 95% confidence interval is about ±7% of the average of three repeat measurements. The ASSP, which weighs less than 4 kg, is light enough to be flown suspended below a tethered helium-filled balloon or attached to a small radio-controlled aircraft. Measurements are made by flying the sampling equipment into a fire's smoke plume. Additional smoke plume measurements that can be made with the ASSP include particle size distribution using a cascade impactor, smoke agglomerate structure using transmission electron microscope (TEM) grids, and polycyclic aromatic hydrocarbons (PAHs) analysis using various sorbent tubes. The application of the ASSP in measuring laboratory and large outdoors petroleum pool fires is discussed. Smoke yield values measured in field burns of Louisiana crude oil range from 0.080 to 0.137, and the primary sphere diameter of the agglomerates is as large as 0.15 µm.
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    Fire technology 30 (1994), S. 232-249 
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    Notes: Abstract Many complex problems in commercial settings can be broken down into elements that can be arranged in a hierarchical network with a supreme policy level and subsequent lower levels. Several techniques can be used to quantify the relative importance of the lowest level components subject to the policy. In this paper, we compare three methodologies that have been used in fire safety evaluation (FSE) research and show how some of the problems in these can be overcome. Of particular interest is a modification to Saaty's analytic hierarchy process (AHP), which improves its consistency and robustness to enable more confident application of the method in the “fuzzy environment.” The comparative results for a practical example are provided as an illustration.
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    Fire technology 30 (1994), S. 250-268 
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    Notes: Abstract In this paper, we present new methods of reducing the number of false alarms in smoke detectors and apply these methods to an ionization smoke detector. The detector is able to diagnose its working condition and its environment very precisely. When the detector's environment changes, the detector can automatically determine the cause, whether the change is fire-related or not. This is done by measuring the ionization current in two sensitivity ranges of the measurement chamber and analyzing the results with new algorithms. With the help of algorithms that use fuzzy logic, we can identify basically every potential problem an ionization detector can produce.
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    Fire technology 30 (1994), S. 281-287 
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    Fire technology 30 (1994), S. 278-280 
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    Fire technology 30 (1994), S. 288-288 
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    Fire technology 30 (1994), S. 289-290 
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    Fire technology 30 (1994), S. 269-277 
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    Notes: Abstract Since the Fall of 1992, the University of Central Florida (UCF) and the Orange County Fire Rescue Division (OCFRD) have conducted a joint research program to evaluate the effectiveness of positive pressure ventilation (PPV) as a firefighting technique. The objectives of the research program are to quantitatively measure temperature, air quality, and visibility during actual live fire exercises. Using the data from three residential fires, a novel technique was developed to conduct underwater, scale-model PPV simulations. PPV is a technique that uses fans with high volumetric flow rates to create a slight positive gage pressure within a structure to force heat and combustion products from strategically selected exhaust openings. This rapidly reduces temperatures and retards the combustion process by hindering pyrolysis (the conversion of solid fuel to gaseous, combustible fuel). The removal of smoke improves visibility inside the structure, and the survivability potential for victims is increased by removing toxic gases, lowering temperatures, and introducing fresh air. Results suggest that PPV is an effective technique that can be of significant value when properly applied. Results, specific to this program, that exemplify advantages of PPV include: 1. Reduced temperatures for firefighters and victims. At key firefighting positions, for example, PPV contributed to temperature reductions from 860°F to 140°F within 1 minute. 2. Improved air quality for firefighters. PPV was shown to contribute to oxygen addition and carbon monoxide removal. 3. Faster smoke removal and faster restoration of visibility. When PPV was used, firefighters had water on a residential fire 6 minutes after it began and were walking upright in a cool, highvisibility environment. By contrast, 8 minutes after the start of a second, identical fire in which PPV was not used, firefighters were still crawling around in a hot, smoke-filled environment. 4. Reversal of the direction of flames away from the firefighting location. For example, flashover flames that entered a hallway were pushed back into the burning room soon after the start of PPV. 5. No spread of heat damage. Examination of lateral extent and depth of char on pine 2x4s placed in the path of the flames for PPV and non-PPV fires showed no spreading of heat or flame damage caused by PPV. Full-scale PPV research and training can be expensive. During the course of this project, a technique was developed to conduct scale-model PPV simulation. The simulations are conducted underwater with transparent scale models of residences. The thermodynamics of the fire and the fluid mechanics of PPV are simulated by injecting colored water dyes at rates determined from actual fire measurements. Results from the residential fires colorfully illustrate that the spread of heat and the effects of PPV can be accurately and safely simulated in the laboratory.
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    Fire technology 30 (1994), S. 304-325 
    ISSN: 1572-8099
    Keywords: fire model ; compartment fires ; roof vents ; sprinklers
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    Topics: Architecture, Civil Engineering, Surveying
    Notes: Abstract CALFIRE, the acronym for CALculate Fire In Room and Enclosure, is a knowledge-based mathematical formulation of analytical and numerical procedures to predict the consequences of a fire in a room or enclosure. CALFIRE is a well-knit and integrated computer model that offers menu items such as heat release rate (HRR), flame height, vent size, and room temperatures of closed rooms, and rooms with natural and forced ventilation. Warnings and checks have been provided to prevent the misuse of the model. Care has been taken to require minimal keyboard responses in order to make CALFIRE a truly user-friendly, interactive fire model.
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    Fire technology 30 (1994), S. 291-303 
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    Topics: Architecture, Civil Engineering, Surveying
    Notes: Abstract This paper describes the use of the general-purpose finite-element code ABAQUS to temperature analysis of concrete structures exposed to fire. Various structural members are studied, such as rectangular beams, slabs with circular enclosures, and steel-concrete composite slabs. The thermal analysis allows us to establish the temperature distribution in the structural members throughout the fire history. Influences of phase changes and other nonlinearities are taken into account. The results are compared with results from the computer codes TASEF and SUPER-TASEF.
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    Fire technology 30 (1994), S. 341-356 
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    Topics: Architecture, Civil Engineering, Surveying
    Notes: Abstract The paper starts with the introduction of the basic requirements of classical intrusion detection and alarm systems, and fire detection systems. The drawbacks of such conventional systems are highlighted. Techniques of computer vision are employed to remove the drawbacks and at the same time, increase the reliability and response rate of the systems. For security and low-level fire detection, a fuzzy-logic-based image-comparison algorithm is deemed adequate. In order to confirm the existence of fire or smoke, techniques related to optical flow are employed as high-level fire or smoke detection which generate a velocity field for the image so that the decision can be judged using fuzzy logic. Details of implementation and some experimental results have been included in the paper for illustration.
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    Fire technology 30 (1994), S. 366-373 
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    Notes: Abstract The comprehensive application of fire safety engineering in modern buildings makes the quality of fire safety equipment a very important aspect of the achievement of fire safety. With its direct relevance to the safety of human life and property, the quality of fire safety engineering in buildings is of concern not only to builders and their clients, but also to various social groups and organizations, ranging from government bodies and business organizations to the individual users of the buildings. Results of the recent research by the authors indicate that the government, insurers, quality certification bodies, building authorities, fire authorities, and trade and professional bodies significantly influence the development of quality assurance in the fire protection industry in the United Kingdom. In this article, the authors explore how these social groups and organizations play their roles in the development of a macro system for quality assurance in the fire protection industry in the U.K.
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    Fire technology 30 (1994), S. 376-378 
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    Fire technology 30 (1994), S. 379-381 
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    Fire technology 30 (1994), S. 382-383 
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    Fire technology 30 (1994), S. 384-384 
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    Fire technology 30 (1994), S. 385-386 
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    Fire technology 30 (1994), S. 387-399 
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    Keywords: Solid particulate aerosols ; pyrotechnically generated aerosols ; fire suppression aerosols ; solid particulate fire suppression aerosols
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Abstract A variety of private and public sector programs are developing a new class of fire suppressants, known generically as solid particulate aerosols. These have superior volumetric efficiency, low initial and life-cycle costs, low toxicity, no known global atmospheric environmental impacts (ODP/GWP), and the potential for a wide variety of applications. Researchers are developing solid compound formulations that, when pyrotechnically initiated, generate powerful fire suppressant aerosols that behave more lightly than do air gases. Preliminary indications show that these aerosols are up to four times more powerful as fire suppressants on a mass basis than Halon 1301. Using a solid, gel, or powder as the starting point for generating an aerosol eliminates the need for piping and pressure cylinders and creates a potential for a wide variety of fire suppression applications in facilities, aircraft cargo containers, portable rapid deployment shelters, fuel storage tanks, battery/UPS rooms, unstaffed telecommunications facilities, and armored vehicle engine compartments. The speed of aerosol formation depends upon system design and configuration. This paper covers mechanisms of aerosol fire suppression and presents the most recent test results.
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    Fire technology 30 (1994), S. 445-457 
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    Notes: Abstract A number of major innovations have recently been achieved using techniques that employ small-scale flammability measurements to predict full-scale end-use applications. The principles used couple ignition characteristics with combustion characteristics to assess fire performance. These techniques have been developed to classify the flammability of aerosol products; characterize liquid fuel spray fires, such as those involving hydraulic fluids; evaluate the fire propagation behavior of electrical cables; classify conveyor belts; and determine the fire propagation behavior of wall/ceiling materials.
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    Fire technology 30 (1994), S. 432-444 
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    Notes: Abstract The relative impact of two experimental conditions—rehearsal-plus and behavioral rehearsal—was assessed to determine their influence on acquiring and maintaining fire evacuation skills, as well as reducing fire-related fears. These experimental conditions were compared with two control groups, attention control and wait-list control. The subjects were 40 second- and third-grade children who were randomly assigned to the four groups. Behavioral rehearsal subjects received fire evacuation skills training and verbally rehearsed these skills. Rehearsal-plus subjects were taught fire evacuation skills and a strategy targeting reduction of fire-related fears. Attention control and wait-list control subjects were not taught evacuations skills or fear reduction. All subjects' evacuation skills and fear of fire-related stimuli were assessed at pre-, post-, and follow-up tests. No pretest differences were observed. At post-test, the rehearsal-plus group reported significantly more fear reduction than the other three groups. Behavioral rehearsal and rehearsal-plus groups displayed significantly more evacuation skills than the control groups. At follow-up, the rehearsal-plus group had retained more of their evacuation skills than the control groups; no differences were found among groups concerning fear reduction at this time. We concluded that rehearsal-plus appears to be useful in acquiring and maintaining fire evacuation skills, as well as reducing fire-related fears.
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  • 57
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    Notes: Abstract Data were collected from eight cities on a wide range of cigarette and smoker characteristics for a sample of smokers. Of these, 564 smokers had had fires and were identified through fire department response to those fires, while the other 1,611 smokers had not had fires and were identified through a telephone sample survey of the communities. The characteristics analyzed included those that had shown evidence of a relationship to the risk of a cigarette-initiated fire, either in laboratory studies or in previous statistical analyses of fire experience. The smoker characteristics analyzed were household income, education, age, gender, and race. The cigarette characteristics analyzed were filter, tobacco column length, filter length, circumference, density, amount of tobacco, menthol, citrate, porosity, and pack type. In addition, a variable was used to control for the smoker's city. After controlling for all smoker characteristics and city, logistic regression modeling showed four cigarette characteristics to be significant: filter, filter length, porosity, and type of pack. Filter, filter length, and porosity all affect air intake, which, therefore, appears to be an important physical element in the combustion process associated with risk. Analysis limited to filtered cigarettes only showed the same characteristics to be significant, plus tobacco column length. Extension of the analysis to two-way interaction terms did not change any of the conclusions on which cigarette characteristics are important, but it did indicate that the role of pack type was different for men and women. Sensitivity analyses, shown in the appendix, supported the main conclusions that cigarette characteristics are significant after controlling for smoker characteristics and that the four specific cigarette characteristics—filter, filter length, porosity, and pack—are the ones that are significant. These analyses checked the impact of cluster sampling, sensitivity to missing data on smoker characteristics, and sensitivity to nonfire smoker cases with responses by people other than the smokers themselves. All this means that there are already cigarettes commercially available that exhibit a reduced propensity for ignition when one controls for smoker characteristics.
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    Journal of chemical crystallography 24 (1994), S. 21-26 
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    Notes: Abstract The emphasis of computational chemistry has traditionally been slanted toward the study of isolated organic systems, and in particular toward methods of drug design. The requirements for the study of materials are different, we are often concerned with metal containing species and properties that arise from interactions between unit molecules in the solid state. We have developedcrystal, a molecular modeling environment that provides both the capability to perform calculations on metal complexes, and an array of visualization tools to aid in the design of solid-state systems.
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    Journal of chemical crystallography 24 (1994), S. 51-60 
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    Notes: Abstract Two recent examples in X-ray structure analysis at opposite ends of the molecular weight range, in which very careful consideration of space group and diffraction symmetry was necessary to resolve all the associated problems, are described. Case 1 involves the structures of (1) transdiBromo (1,4,8,11-tetraazacyclotetradecane) chromium (III) bromide and (2) the corresponding trans-bromo-chloro compound. Both crystallise in space groupP42/m with unit cell dimensions sufficiently close to suggest that the structures are isomorphous. It is shown however that the structures are not superimposable or even related by simple rotation or inversion, but that it is necessary to apply a hypothetical glide operation in order to bring the structures into coincidence. The organic moieties are thus structural enantiomorphs in spite of existing in a centrosymmetric space group. Case 2 involves studies on a co-crystallised derivative of the enzyme RNase with deoxycytidylyl-3′–5′-deoxyguanosine (dCpdG). Preliminary X-ray precession photographs, from low quality crystals, indicated an orthogonal C-centred unit cell, but were unable to define the true diffraction symmetry, which wasnot orthorhombic. The true symmetry was discovered only after solving the structure in a second (erroneous) cell and careful inspection of the lattice and diffraction symmetry from the measured intensity values.
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    Notes: Abstract The title compund C22H26N2O4,Mr=382.46 crystallizes in the orthorhombic space group P212121 with α=8.867(1)Å,b=13.228(2)Å,c=17.029(3)Å,V=1956.7(2)Å3,Z=4, Dcal=1.30 Mgm−3,F(000)=816, μ=6.89 cm−1, λ(CuKα)=1.5418 Å andT=298 K. The structure was solved by direct methods and refined by full-matrix least-squares. The finalR=0.046 for 1995 unique reflections. The phenyl rings are coplanar (oriented at an angle of 6.4(1)o) and orients at an angle of 112.2(1)o and 115.7(1)o, respectively with the piperazine ring. The piperazine ring adopts achair conformation and the substituents at the N-atoms are in an equatiorial position.
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    Notes: Abstract MMP: C17H26N2O3,M r =306.40, monoclinic, space groupP21/c,a=10.927(2),b=10.777(2),c=14.197(2) Å, β=94.04(2)°,V=1667.7(5) Å3,D cal=1.22 Mgm−3,Z=4,F(000)=664, μ=5.93 cm−1,T=293K. FinalR=0.049 andwR=0.063 for 2724 observed reflections. MBrP; C16H23N2O3Br,M r =371.27, monoclinic, space groupP21/c,a=10.955(1),b=10.785(1),c=14.213(1) Å, β=94.54(2)°,V=1674.0(4) Å3,D cal=1.48 Mgm−3,Z=4,F(000)=768, μ=32.35 cm−1,T=293K. FinalR=0.055 andwR=0.069 for 2886 observed reflections. MMP and MBrP are isostructural and in both the molecules the morpholino rings assume a chair conformation.
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    Notes: Abstract The X-ray crystal structure of the drug N-(2,6-dioxo-3-piperidyl)pthalimide (thalidomide), C13H10N2O4, obtained from 1∶1 dimethyformamide-ethanol solution, is reported. This species is monoclinic, space groupC2/c, witha=20.679(5),b=8.042(2),c=14.162(5) Å, β=102.86(3)°,Z=8,R=0.051 for 1674 unique reflections. crystal packing is determined by intermolecular N−H... O hydrogen bonding which is more extensive than that reported in the literature for a racemate of thalidomide crystallizing in space groupP21/n. Comparison of the melting behavior and X-ray powder diffractograms of the two racemic polymorphs shows that they are distinctly different, allowing easy identification of these species. By comparing experimental X-ray powder patterns with those calculated from single crystal data, it was concluded that neither of these polymorphs undergoes a phase change on trituration.
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    Keywords: X-Ray diffraction studies
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    Notes: Abstract The crystal and molecular structure of the title compound, ·[Pd(S=C(NH2)2)4]Cl2·2dmtp·2H2O. has been determined and refined to a finalR=0.034. The cation is centrosymmetric with the Pd atom existing in a square planar geometry with two disparate Pd−S bond distances of 2.3129(9) and 2.292(1)Å. Interatomic parameters are reported for the first non-coordinated dmtp molecule; these suggest the predominance of a particular canonical form in the solid state. The lattice is stabilized via a series H-bonding contacts involving the thiourea. Cl− and dmtp species. Crystals of [Pd(S=C(NH2)2)4]Cl2 · 2dmtp · 2H2O are monoclinic with space groupP21/c, and unit cell dimensionsa=15.129(1),b=8.512(1),c=12.663(1) Å, β=104.05(1)°.
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    Journal of chemical crystallography 24 (1994), S. 681-684 
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    Keywords: Silver(I) ; anionic forms ; 2-pyrazinecarboxylic and 2,3-pyrazinedicarboxylic acids
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    Topics: Geosciences , Physics
    Notes: Abstract X-ray analysis has shown that the complexes of silver(I) with the anionic forms of 2-pyrazinecarboxylic and 2,3-pyrazinedicarboxylic acids are three-dimensional network polymers. Ag(C5H3O2N2) (1) crystallizes in space groupPna21 witha=7.028(2),b=11.510(3),c=6.949(2) Å andZ=4. Silver tetrahedral coordination occurs through three ligands: the first one acts as a bidentate chelator (Ag−O=2.539(4), Ag−N=2.334(4)Å), the second one involves one N pyrazine atom (Ag−N=2.196(4)Å) and the third one bonds through one O-carboxylato atom (Ag−O=2.323(4)Å). The dinuclear complex Ag2(C6H2O4N2)(NH3) (2) crystallizes in space groupP21/c witha=7.775(2),b=16.455(2),c=7.174(1) Å, β-115.21(1)° andZ =4. Each of the two silver atoms shows a trigonal environment. The first silver atom involves two O carboxylic atoms (Ag−O=2.312(4), 2.374(4)Å) and one N pyrazine atom (Ag−N=2.277(3)Å) belonging to three different ligands. The second one involves one O carboxylic atom (Ag−O=2.364(3)Å) and one N pyrazine atom (Ag−N=2.304(4)Å) from the same chelating ligand and one N ammine atom (Ag−N=2.158(5)Å).
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    Journal of chemical crystallography 24 (1994), S. 101-101 
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    Keywords: Molecular and crystal structures ; antimicrobial activity testing
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    Notes: Abstract The molecular and crystal structures of the title compound have been determined. The crystals are monoclinic:P21/n (14),a=11.072(2),b=14.556(2),c=17.569(3)Å, β=97.85(1)°.V c=2805Å3,Z=4,D x=1.285 Mg m−3, MoKα(λ=0.71069 Å). The molecule adopts a twisted conformation in which the relative orientations of the pyridine nitrogen atoms N101 and N201 with respect to the C−S−C angle are N101-inside. The AM1 and PM3 semiempirical calculations performed agree with the crystal structure. Mass and spectral data (ir. uv,1H and13C nmr) are also reported. Thein vitro tests indicate absence of antimicrobial activity.
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  • 68
    ISSN: 1572-8854
    Keywords: Hydrated adducts ; olefinic double betaine ; very strong hydrogen bonds
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    Notes: Abstract The hydrated 1:1 adducts of an olefinic double betaine with perchloric and nitric acids, L·HClO4·H2O I and L·HNO3·N2O2 [L=cis-(p-Me2N+C5H4N)2C2(COO−)2], have been shown to be nearly isostructural by X-ray crystallography and infrared spectroscopy. The common cationic unit HL+ of both compounds exhibits significant semi-quinonoid character and possesses symmetrym, ist two coplanar carboxylate groups being linked by a very strong, nearly linear intramolecular O−H−O hydrogen bond [O...O 2.397(9)Å and O−H−O 167.1° for1; 2.388(7)Å and 167.4° for2]. The HL+ units are further connected by intermolecular O−H...O hydrogen bonds between the exocyclic carboxyl oxygen atoms and the water molecules to generate polymeric zigzag chains running parallel to thec axis, and the disordered ClO4 or NO 3 − anions occupy channels running parallel to thea axis in the resulting host lattice.
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  • 69
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    Journal of chemical crystallography 24 (1994), S. 707-710 
    ISSN: 1572-8854
    Keywords: Crystal structure ; platinum ; xanthate ; square planar
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    Notes: Abstract The crystals of Pt(S2COEt)2 are orthorhombic, Pbca, with (at 20°C)a=7.799(3),b=7.368(6),c=20.588(7) Å.D cale=2.46g cm−3 forZ=4. The platinum atom resides on a crystallographic center of inversion and is bound to the four sulfur atoms of the xanthato ligand in a square planar geometry. The Pt−S distances are 2.313(6) and 2.320(7)Å with an intraligand S−Pt−S angle of 75.1(2)°.
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  • 70
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    Journal of chemical crystallography 24 (1994), S. 715-717 
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    Keywords: cuprate ; diyne ; herringbone
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    Notes: Abstract Crystals of 1,4-Diphenylbutadiyne,1, have been isolated from the decomposition of the cuprate prepared from the reaction between lithium phenylacetylide and copper(I)cyanide in diethylether solution at room temperature. 1,4-Diphenylbutadiyne,I, organizes itself into the expectedherringbone motif in the solid state.
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  • 71
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    Journal of chemical crystallography 24 (1994), S. 725-729 
    ISSN: 1572-8854
    Keywords: Pyrimido [2,1-b]quinazoline ; hydrochloride ; neuroleptic
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    Notes: Abstract C11H11N3O, m.p. 243°C, P2/n,Z=4,a=5.843(2),b=14.241(3),c=11.102(1) Å, β=93.30(2)°,R=0.046; C11H11N3O·HCl·H2O, Pca21,Z=8,a=18.640(2),b=8.894(2),c=14.404(2)Å,R=0.062. The molecules of the free base are in 1H-tautomeric form. N(1)-H...N(11) hydrogen bonds join molecules of the free base into dimers, which enable tautomeric rearrangement (not observed in this study) also in the solid state without any changes in molecular packing. The quinazoline system deviates slightly from planarity and benzene π electrons are partially localized at C(7)−C(8) and C(9)−C(10) bonds as seen from their lengths of about 1.375 Å, while other bonds in the benzene ring are at least 0.02 Å longer.
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  • 72
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    Journal of chemical crystallography 24 (1994), S. 743-746 
    ISSN: 1572-8854
    Keywords: Methylphenylhydrazone ; ketohydrazone ; tautomeric form
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    Topics: Geosciences , Physics
    Notes: Abstract The molecule crystallizes in a ketohydrazone tautomeric form. The tautomeric form is stabilized by a strong intramolecular hydrogen bond of 2.709(2) Å binding the 3-oxo to the nearest nitrogen atom in the azine chain. The compound crystallizes in the monoclinic space group P2l/c witha=7.0470(4),b=11.3090(9),c=16.2250(4) Å, β=90.310(3)°, V=1293.0(1) Å3, Z=4,Dx=1.3576 g cm−3 and μ(Cu-Kα)=7.03 cm−1. The molecule is nearly planar not regarding the methyl group; the small deviations from planarity are indicative of intramolecular interactions between the phenylazo group and indandione group. Some of the bond lengths and angles found in the molecule are distorted due to resonance, π-electron delocalization and strain. The relation between these chemical effects and structural results are discussed.
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  • 73
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    Journal of chemical crystallography 24 (1994), S. 759-762 
    ISSN: 1572-8854
    Keywords: Sulfonamide ; methanesulfonanilide ; crystal structure ; molecular structure
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    Topics: Geosciences , Physics
    Notes: Abstract The title compound, crystallizes in the triclinic space group $$P\bar 1$$ witha=8.232(4),b=9.159(2),c=10.230(3)Å. α=74.07(3)°, β=72.50(4)°, γ=63.65(3)° andZ=2. The structure was solved by direct methods and refined by full matrix least squares methods toR=0.054 for 1817 observed reflections. The plane containing the nitrogen and sulfur atoms is perpendicular to the aromatic plane. One of the S−O bonds in each methanesulfonyl group is in nearly eclipsed conformation with the N−C bond.
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  • 74
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    Journal of chemical crystallography 24 (1994), S. 783-791 
    ISSN: 1572-8854
    Keywords: Cholic Acid ; Inclusion Compounds ; Ketone Guests
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    Topics: Geosciences , Physics
    Notes: Abstract Cholic acid forms inclusion compounds with acetone, methyl ethyl ketone and diethyl ketone. Crystal structures with these closely related guest molecules indicate variations in packing which result in respectively: unusual 2∶3 host: guest stoichiometry and loss of the 21 screw axis, doubling of the c axis with formation of two different channels and the usualP21 structure with 1∶1 host: guest stoichiometry.
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  • 75
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    Journal of chemical crystallography 24 (1994), S. 797-800 
    ISSN: 1572-8854
    Keywords: La(III) ion ; phen ; Lanthanides
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    Notes: Abstract [La(OH2)5(phen)2]Cl3·4H2O·phen is centric, Pnna, witha=19.946(7),b=16.458(5),c=12.207(4)Å andD calc=1.57 g cm−3 forZ=4. The La(III) ion resides on a crystallographic twofold axis and is coordinated to four nitrogen atoms (from two phen molecules) and five water molecules resulting in a distorted tricapped trigonal prismatic geometry. An uncoordinated phen molecule, two chloride anions, and four uncoordinated water molecules are hydrogen bonded to the coordinated water molecules. The coordinated and uncoordinated phen molecules π-stack diagonally through the unit cell.
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  • 76
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    Journal of chemical crystallography 24 (1994), S. 817-817 
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  • 77
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    Journal of chemical crystallography 24 (1994), S. 815-816 
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  • 78
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    Journal of chemical crystallography 24 (1994), S. 123-128 
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    Notes: Abstract Crystals of Na16[Zn4(H2O)2(α-P2W15O56)2]·∼50H2O are triclinic, $$P\bar 1$$ , witha+14.670(5),b+14.661(5),c+19.817(3)Å, α=84.95(3), β=81.51(3), γ=65.73(3)o. Least-squares refinement converged atR+0.053 for 5906 independent data withl〉3σ(I). The centrosymmetric anion consists of two α-P2W15O 56 12− ligands attached to a planar group of four Zn2+, two of which also carry water molecules. The distortions in the ZnO6 octahedra and in the W15 framework of the ligands are smaller than the corresponding distortions in the otherwise similar [Cu4(H2O)2(P2W15O56)2]16− anion.
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  • 79
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    Journal of chemical crystallography 24 (1994), S. 133-137 
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    Notes: Abstract The structure of the title compound. [Cu2Cl2(C9H10NO2)2]·1/2H2O. has been determined from single crystal X-ray diffraction data. The structure was solved by direct methods. Full-matrix leastsquares refinement of structural parameters led to a conventionalR factor of 0.056 for 3689 intensities above 3σ(l). There are two independent molecules [A andB] of the title compound in the asymmetric unit. These molecules are linked to one water molecule by a system of four hydrogen bonds. The comlexes contain pairs of deformed square-pyramidal copper(II) centers. A tridetate ligand L forms two condensed chelate rings with mean Cu−O(C−O)+1.900(6), mean Cu−O(C−OH)+2.004(6) and mean Cu−N-1.930(6)Å. A chloride ions complete the tetrahedral distorted basal plane of each Cu(II) ion forming a square pyramid with the longer fifth apical Cu−Cl bridging bond. The Cu...Cu nonbonding distances in the complexes are 3.445(1)Å for moleculeA and 3.494(1)Å for moleculeB.
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  • 80
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    Journal of chemical crystallography 24 (1994), S. 151-154 
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    Notes: Abstract The crystal and molecular structures of 2-Hydroxy-1-naphthalenecarboxaldehyde (I) and 3-Hydroxy-2-naphthalenecarboxaldehyde (II) were determined. Compound (I) crystallizes in the space groupP2 1/n witha+5.589(2),b+9.352(2), andc+15.490(3) Å, β=98.14(3)°, andZ+4. Compound (II) crystallizes inP2 1/n witha+16.831(11),b+5.936(3), andc+8.295(3) Å β=97.24(5)°. andZ+4. The structures were solved by direct methods, and refined by fullmatrix least squares toR+0.071 andR w+0.083 forI, andR+0.047 andR w+0.061 forII.
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  • 81
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    Notes: Abstract The title compound crystallizes in the monoclinic space group P21/a, witha+12.906(9).b+11.604(2).c+14.631(9) Å, β=108.70(3)° andZ+4. The structure was solved by direct methods from diffractometer data and refined to a finalR value of 0.057 for 2020 independent reflections. The structure analysis confirms the cis disposition of the bulky substituents and indicates a puckered four-membered ring with a dihedral angle of 18.5° as expected for a non-centrosymmetrically substituted cyclobutanone.
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  • 82
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    Journal of chemical crystallography 24 (1994), S. 193-195 
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    Notes: Abstract C30H51NO4P2Pt-[C2H3N], orthorhombic,Pbca, a=16.132(1),b=16.610(2),c=24.001(2) Å.Z=8,D c=1.54 g cm−3,R=0.042,R w=0.048, GOF=1.33. The platinaoxalate (PtC2O2) ring fragment is essentially planar with Pt−O bond lengths of 2.067(8) and 2.058(7) Å.
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  • 83
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    Notes: Abstract The crystal structures of [Zn(O2CC(CH3)CHCH3)2]x and [Zn2(O2CC(CH3)CHCH3)3-(O2CCHCHCH3)]x have been determined by single crystal X-ray diffraction. Both structures consist of chain polymers, in which pairs of zinc atoms are bridged alternately by three syn-syn carboxylates and by one syn-anti carboxylate. In the mixed carboxylate structure, the crotonate takes up preferentially the syn-anti bridge position. Vibrational and elemental analysis data indicate that the spontaneous solid-state reaction of zinc tiglate in air, accelerated for the tiglate and observable also for the mixed carboxylate compound by γ-ray or X-ray irradiation, gives an oxocentered tetranuclear complex [Zn4O(O2CR)6] rather than a polymerization through cross-linking of the unsaturated carboxylates.
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  • 84
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    Notes: Abstract The crystal and molecular structure of 17a-methyl-3-pyrrolidino-17a-aza-D-homo-5-androstene dimethyl bromide (HS818, chandonium dibromide). C26H46N2Br2, has been determined crystallographically by the heavy atom method and refined by full-matrix least-squares calculations toR =0.074 for 5045 reflections. The compound crystallizes in space groupP212121 witha=6.468(2),b=14.055(5),c=28.216(11) Å. The N+...N+ inter-onium distance in chandonium bromide is 10.32 Å, close to the distance of 10.29 Å observed in chandonium iodide. Rings A, C, and D have a chair conformation and ring B is in a half-chair conformation. Ring E has a distorted envelope conformation. All rings in the steroid skeleton aretrans-connected.
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  • 85
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    Notes: Abstract [H3O+·18-crown-6][Br−Br−Br−] crystallizes in the triclinic space group P 1 witha=6.105(1),b=8.658(1),c=11.072(1)Å, α=71.35(1), β=77.58(1), γ=71.09(1)0, andD c=1.68 g cm−3 forZ=1. Refinement based on 1112 observed reflections led toR=0.044. The cation exhibits a planar oxonium ion bonded symmetrically to the 18-crown-6 (O(oxonium) resides 0.092 Å out of the plane of the crown ether oxygen atoms). The anion also resides on a center of inversion with Br−Br=2.530(1)Å.
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  • 86
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    Notes: Abstract 2,8,10,11-Tetrachloro-12-oxahexacyclo[7,2.1.02.8.03.7.04.11.06.10]dodeca-1,9-diol is a strained cage molecule containing six five-membered rings and a four-membered ring. Twenty-five of the internal angles are less than 105° with 6 ranging from 89.5(3) to 97.4(3)°. The base promoted reaction of 3,6-dipyridyl-1,2,4,5-tetrazine with tetracyclo[6.3.0.04.11.05.9]undecane-3,6-dione yields the monoketone 6,7-[3′,6′-di(2″-pyridyl)-4′,5′-pyridizino]tetracyclo[6.3.0.04.11.05.9]-undecan-2-one. This compound crystallizes in the centrosymmetric space group P21/n with enantiomers related by a center of symmetry. In the crystal investigated the molecules are disordered with each site containing about 80% of one isomer and 20% of the enantiomer. When the ketone is hydrogenated and the product isolated, two different crystals were found to have a ratio of alcohol to ketone of .71/.29 and .75/.25 or about 3/1. The alcohol and ketone occupy the same sites, but with opposite stereochemistries.
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  • 87
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    Notes: Abstract [(C2H4N3S) (C2H3N3S) BiI4]∞; [(HL) (L) BiI4]∞ (L=2-amino-1,3,4-thiadiazole),M r=919.86. monoclinic, P 1 21/a 1,a=7.622(1),b=18.977(2),c=12.821(1) Å, β=102.77(1)°, finalR=0.033. The crystals consist of HL+ cations, neutral L molecules and polymeric [BiI4] ∞ − anions built up of edge-sharing [BiI6]3− octahedra, with Bi−I(bridging) distances in the range 3.320(1)−3.057(1) Å and Bi−I(terminal) distances in the range 2.917(1)−2.929(1) Å. The1H and13C spectra in DMSO-d6 solution are used in conjunction with the X-ray structural results to establish the preferred protonation site of the thiadiazole ring.
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  • 88
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    Journal of chemical crystallography 24 (1994), S. 285-287 
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  • 89
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    Notes: Abstract The structures of the nitrostilbene complexes Z-(4-R−C6H4−CH=CH−C6H4-4′-NO2)Cr(CO)3 (R=Me2N,1; H,2; F3C,3), are reported. The copounds were prepared as part of a study of the synthesis of organometallic complexes with potential nonlinear optics applications. For Z-(4-Me2N−C6H4−CH=CH−C6H4-4′-NO2)Cr(CO)3,1, triclinic, $$P\bar 1$$ ,a=7.214 (3) Å,b=7.340 (3) Å,c=17.238 (9)Å, α=88.23 (5)°, β=88.76 (4)°, γ=87.66 (3) °,Z=2. For Z-(C6H5−CH=CH−C6H4-4′-NO2)Cr(CO)3,2, monoclinic, P21/C,a=12.255 (3) Å,b=9.415 (1) Å,c=13.579 (4) Å, β=105.60 (2)°,Z=4. For Z-(4-F3C−C6H4−CH=CH−C6H4-4′-NO2)Cr(CO)3,3, triclinic, $$P\bar 1$$ ,a=7.094 (2) Å,b=8.057 (5) Å,c=17.295 (9) Å, α=87.95 (5)° β=85.94 (4)°, γ=64.24 (5)°,Z=2. The structural data show that the Z isomers exhibit bond lengths and angles similar to those observed in the E isomers, but the stilbene fragment is considerably more nonplanar. As a consequence, these molecules are unlikely to behave as NLO materials.
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  • 90
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    Notes: Abstract 1-(2-Hydroxyphenyl)-3-phenyl-1,3-propanedione crystallizes in the triclinic space group $$P\bar 1$$ (a=5.4233(5),b=13.910(1),c=17.036(1) Å, α=68.311(6), β=80.854(7), γ=78.760(8)°) as two independent enolic tautomers in which the hydroxyl and phenolic protons are hydrogen bonded to the ketonic oxygen atom. The structure was refined toR=0.039 for 2085I≥3σ(I) reflections. 1-(1,3-Benzodioxol-5-yl)-3-(2,4-dimethoxyphenyl)-1,3-propanedione, which belongs to the triclinic $$P\bar 1$$ space group (a=7.3990(7),b=8.1239(5),c=14.004(1) Å, α=86.673(6). β=88.574(7), γ=64.885(7)°) also exists in the enolic form. The structure was refined toR=0.040 for 1564I≥3σ(I) reflections.
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  • 91
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    Journal of chemical crystallography 24 (1994), S. 353-353 
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  • 92
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    Notes: Abstract The solid-state structures of four 1,2,3,4-tetrahydroacridines [tacrine hydrochloride monohydrate (1), 7-methoxytacrine hydrochloride monohydrate (2), velnacrine hydrogenmaleate (3) and suronacrine hydrogenmaleate (4)] were determined from single-crystal X-ray diffraction analysis. (1): monoclinic,P21/n, a=8.778(1),b=8.521(1),c=17.603(2)Å, β=101.34(1)°. (2): monoclinic,C2/c, a=12.326(7),b=18.050(9),c=13.822(8)Å, β=113.70(4)°. (3): triclinic, $$P\bar 1$$ ,a=7.349(2),b=9.417(3),c=12.557(4)Å, α=109.62(2), β=98.12(2), γ=101.18(2)°. (4): monoclinic,P21/n, a=8.513(6),b=18.74(1),c=13.401(6)Å, β=91.21(5)°. FinalR factors for compounds(1)–(4) are 0.047, 0.057, 0.057, 0.11, respectively. The overall arrangement of the common aminotetrahydroacridine skeleton looks similar in all derivatives. However, whereas enantiomerization of the unsubstituted cyclohexenyl rings occurs in (1) and (2), onlyquasi-axially hydroxyl substituted diastereomers are found for (3) and (4). This is presumably due to the different propensities for hydrogen bonding of axially vs. equatorially disposed hydroxyl groups with the hydrogenmaleate anions. Empirical and semiempirical calculations were performed to examine the conformational behavior of the four compounds, bothin vacuo and in solution.
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    Journal of chemical crystallography 24 (1994), S. 337-340 
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    Notes: Abstract Triphenyltin diethylphosphonoacetate, which crystallizes in the monoclinc space groupP21/c (a=15.154(4),b=9.159(3),c=17.685(4) Å, β=91.410(8)°), adopts a polymeric structure in which planar triphenyltin cations (∑C—Sn—C=357.3(6)°) are axially linked by the diethylphosphonoacetato anions (Sn−Oesteryl=2.129(3), Sn←Ophosphoryl=2.420(3) Å; O−Sn←O=171.9(1)° into chains that propagate by translations along theb-axis. The structure has been erfined toR=0.037 for 3384I≥3σ(I) reflections.
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  • 94
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    Journal of chemical crystallography 24 (1994), S. 391-395 
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    Notes: Abstract Nitrate (1): C14H17N2O+·NO 3 − , orthorhombic, Pbca,Z=8,a=9.6924(4),b=27.664(2) andc=10.8589(6)Å.Hydrogen tartrate dihydrate (2): C14H17N2O+·C4H5O 6 − ·2H2O, orthorhombic, P212121,Z=4,a=7.6703(5),b=7.9368(4) andc=31.953(2)Å. In the solid state, cation conformation differ due to molecular flexibility, very different anionic environments, and resultant hydrogen bonding patterns. Despite these differences, the two structures maintain the same separations (about 7.35 Å) of the two most distant potential pharmacophoric groups, i.e., the aromatic ring and the protonated amine group.
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  • 95
    ISSN: 1572-8854
    Keywords: Bis(2-pyridine-N-oxide) diselenide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The structure of bis(2-pyridine-N-oxide) diselenide was determined by single crystal X-ray diffraction. The compound crystallized in the triclinic system and the structure was solved in the space group $$P\bar 1$$ . The lattice constants were determined to bea=7.174(2),b=7.176(2),c=11.070(2) Å, α=87.67(2)°, β=73.68(2)°, and γ=89.57(2)°;Z=2,D x=1.906 Mg m−3. The final least squares refinement based on 1942 independent observed reflections yieldedR=0.033,wR=0.044. The Se−Se′ bond length is 2.326(1) Å and each Se is coordinated to the O atom of the corresponding N-oxide moiety at a distance of about 2.6 Å.
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  • 96
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 24 (1994), S. 437-440 
    ISSN: 1572-8854
    Keywords: Ca(C4H4O4)·H2O ; pentagonal pyramid ; calcium succinate ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structure of calcium succinate monohydrate, Ca(C4H4O4)·H2O, has been determined by single crystal X-ray diffraction. The crystals are monoclinic witha=11.952(2),b=9.691(2),c=11.606(2)Å, β=108.81(1)°, space group C2/c,Z=8,V=1272.49 Å3,d m =1.80, andd c =1.818 Mg m−3. The structure was refined by full-matrix least-squares techniques toR=0.027,R w =0.040, for 829 reflections with1≥3δ(I). Ca is coordinated to seven oxygen atoms, and the coordination polyhedron is best described as a pentagonal bipyramid. One carboxylate group in the succinate ion is bonded to three different Ca ions, forming a four-membered chelate ring with one Ca ion is bonded to three different Ca ions, forming a four-membered chelate ring with one Ca ion and unidentate bridge bonds to two other Ca ions. The other carboxylate group is bonded to two Ca ions through unidentate bonds. The structure is highly polymeric. The general structural features are nearly identical to those of calcium adipate monohydrate.
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  • 97
    ISSN: 1572-8854
    Keywords: C14H17NO3 ; chair ; half-chair
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A new nitro-octahydrophenanthrenol has been isolated by nitration of a crude 9,10-dihydrophenanthrene, which was identified by nmr and X-ray diffraction analysis. Crystallographic and molecular structure confirmed the compound as therac-(4R*,4aS*,10aS*)-4-Nitro-1,2,3,4,4a,9,10,10a-octahydrophenanthren-4a-ol. The crystal was triclinic, $$P\bar 1$$ ,a=10.549(3),b=8.530(3),c=7.131(1)Å, α=107.07(3), β=91.62(3), γ=96.27(4)°. Cyclohexane and cyclohexene rings aretrans-fused and have chair and half-chair conformations, respectively. The molecules are associated by hydrogen bridge between the hydroxyl oxygen and both nitro oxygens.
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  • 98
    ISSN: 1572-8854
    Keywords: [(PPh3)2N+][CH3C6H4SO 3 − ] ; staggered conformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
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  • 99
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    Springer
    Journal of chemical crystallography 24 (1994), S. 495-501 
    ISSN: 1572-8854
    Keywords: Structural isomers ; enclathration ; inclusion compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structures and thermal analyses of the host compound, N,N,N′,N′-tetraisopropylfumaride, witho-cresol,m-cresol and water are reported and compared to that of thep-cresol complex previously reported in an attempt to elucidate the reasons for host selectivity.
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  • 100
    ISSN: 1572-8854
    Keywords: C23H20O2 ; diketone ; cis arrangement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract 1,3,5-triphenyl-1,5-pentanedione, C23H20O2, has been prepared and characterized by spectroscopic methods and single crystal X-ray analysis. Crystals are monoclinic, space groupP21/n, a=28.124(4),b=5.997(1),c=10.434(1)Å, β-98.42(1)Å,Z=4. The structure has been refined to a finalR-value of 0.040 for 1625 reflections withF o〉3σ(F o). The compound contains the two carbonyl groups in a mutuallycis arrangement.
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