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91.
The adsorption behavior of butyl xanthate on the surface of lead oxide was investigated using continuous online in situ attenuated total reflectance Fourier transform infrared(ATR-FTIR) spectroscopy technique and two dimensional(2D) correlation analysis.The adsorbed layer studied was prepared by coating α-PbO particles onto the surfaces of the ZnSe crystal.The appearance of spectral peaks at 1203 cm-1,1033 cm-1 and their red shift indicated the formation and aggregation of xanthate at the surface of α-PbO.According to 1R intensity changes after rinsing with deionized water and a NaOH solution,the adsorption was proved to be a chemisorption type.The competition between xanthate and OH for the surfaces leads to desorption of xanthate at higher pH.The technique of 2D correlation ATR-FTIR spectroscopy was used to evaluate the changing order of spectral intensities in the adsorption process,and the results indicated that xanthate micelles were formed at the surfaces.The adsorption kinetics of butyl xanthate was found to be a pseudo-second-order reaction model and the adsorption capacity of butyl xanthate at α-PbO was as high as 281 mg g-1 after 150 min. 相似文献
92.
93.
D. Iean 《International Journal of Solids and Structures》2007,44(25-26):8648-8662
This paper is concerned with a linear theory of thermodynamics for elastic materials with microstructure, whose microelements possess microtemperatures. It is shown that there exists the coupling of microrotation vector field with the microtemperatures even for isotropic bodies. Uniqueness and continuous dependence results are presented. The theory is used to establish the solution corresponding to a concentrated heat source acting in an unbounded continuum. 相似文献
94.
V.I. Yudovich S.M. Zenkovskaya V.A. Novossiadliy A.L. Shleykel 《Comptes Rendus Mecanique》2004,332(4):257-262
We consider the dynamical stability of horizontal fluid layer, performing harmonic oscillations in vertical direction. The continued fractions approach allowed us to avoid the conventional restriction to the case of small viscosity and almost-resonant frequencies. Our numerical results cover a wide range of the parameters (viscosity, amplitude and frequency of the oscillation, and depth of the layer). To cite this article: V.I. Yudovich et al., C. R. Mecanique 332 (2004). 相似文献
95.
Rachid Rahouadj Jean-Franois Ganghoffer Christian Cunat 《Mechanics Research Communications》2003,30(2):119-123
In the first part of this contribution, the Lie-symmetries of the principle of least action associated to the constitutive equations of the DNLR formalism of relaxation have been presented. We examine in this second part the continuous symmetries corresponding to the simple case of stress relaxation under isothermal conditions. The well-known principle of time/temperature equivalence is discussed in terms of variational symmetry for the Jacobi’s action functional, and connected to the Onsager’s relation near the thermodynamic equilibrium. 相似文献
96.
The purpose of the present paper is to solve an active control problem of nonlinear continuous system parametric vibrations excited by the fluctuating force. The problem is solved using the concept of distributed piezoelectric sensors and actuators with a sufficiently large value of velocity feedback. The direct Liapunov method is proposed to establish criteria for the almost sure stochastic stability of the unperturbed (trivial) solution of the shell with closed-loop control. The distributed control is realized by the piezoelectric sensor and actuator, with the changing widths, glued to the upper and lower shell surface. The relation between the stabilization of nonlinear problem and a linearized one is examined. The fluctuating axial force is modeled by the physically realizable ergodic process. The rate velocity feedback is applied to stabilize the shell parametric vibrations. 相似文献
97.
A stochastic-structurally based three dimensional finite-strain damage model for fibrous soft tissue
José F. Rodríguez Fernando Cacho José A. Bea Manuel Doblaré 《Journal of the mechanics and physics of solids》2006,54(4):864-886
A fully three dimensional finite-strain damage model for fibrous soft tissue is developed. The model assumes uncoupled contributions for the matrix and collagen fibers, and uncoupled bulk and deviatoric response over any range of deformations. A simple isotropic damage mechanism within the framework of continuum damage mechanics has been used to describe the softening behavior under deformation for the matrix. On the other hand, statistical aspects related to the length distribution of the reinforcing fibers lead to a damage model for the reinforcing material. As a result, a general theoretical framework for constitutive modeling of biological soft tissue with continuum damage is obtained. A theoretical example consisting of a biaxial test of a soft tissue reinforced with two families of collagen fibers has been considered to demonstrate the capabilities of the proposed model and to study the sensitivity to changes in the statistical parameters associated with the reinforcing material. Also, a preliminary numerical example is included to demonstrate the model on a inhomogeneous boundary value problem. Results show that the model is able to capture the typical stress-strain behavior observed in fibrous soft tissue and seems to confirm the soundness of the proposed formulation. 相似文献
98.
Peter B. Luppa Carolin MüllerAlice Schlichtiger 《Trends in analytical chemistry : TRAC》2011,30(6):887-898
Point-of-care testing (POCT) is a laboratory-medicine discipline that is evolving rapidly in analytical scope and clinical application. In this review, we first describe the state of the art of medical-laboratory tests that can be performed near the patient. At present, POCT ranges from basic blood-glucose measurement to complex viscoelastic coagulation assays. POCT shortens the time to clinical decision-making about additional testing or therapy, as delays are no longer caused by transport and preparation of clinical samples, and biochemical-test results are rapidly available at the point of care. Improved medical outcome and lower costs may ensue.Recent, evolving technological advances enable the development of novel POCT instruments. We review the underlying analytical techniques. If new instruments are not yet in practical use, it is often hard to decide whether the underlying analytical principle has real advantage over former methods. However, future utilization of POCT also depends on health-care trends and new areas of application. But, even today, it can be assumed that, for certain applications, near-patient testing is a useful complement to conventional laboratory analyses. 相似文献
99.
Mark York 《Tetrahedron letters》2011,52(47):6267-6270
A synthesis of di-, tri- and tetra-substituted furans from reaction of the corresponding ketones and α-haloketones with LiHMDS is reported. Reaction under continuous-flow conditions gave increased yields and removed the need for external cooling when compared to the unoptimised batch conditions. 相似文献
100.