Bisoprolol fumarate is a beta blocker-type drug substance which has been well known for several decades. However, no relevant data can be found in the literature about its crystal polymorphism. The purpose of this paper was to present two anhydrous forms (Form I and Form II) and a hydrate of bisoprolol fumarate substance. Crystalline forms were studied by various solid-state analytical methods: Fourier transform infrared (FT-IR) spectroscopy, X-ray powder diffraction (XRPD), dynamic vapor sorption (DVS) and thermoanalytical methods (thermogravimetry and differential scanning calorimetry). Thermodynamic stability and solubility of the presented polymorphs were also investigated. Both FT-IR and XRPD methods were found to be suitable for the characterization of the different crystal structures. Thermoanalytical measurements showed that (1) Form I and Form II own clearly different melting points and (2) both Form II and hydrate forms can transform into Form I at higher temperature values. Results of the DVS measurements prove that both Form I and Form II became metastable under extremely humid conditions (>?80% RH) and converted into the hydrate. Thermodynamic stability studies showed that Form I and Form II polymorphs are in enantiotropic relationship with an enantiotropic point at about 40–45 °C. Solubility studies indicated that all of the prepared forms are highly soluble, and no difference was found between them. Considering the recommendations of the corresponding International Conference of Harmonization guideline, it can be stated that no specification is required for crystal polymorphism in case of this substance.
Physisorption and chemisorption of hydrogen on solid-state materials are two fundamentally different interactions, both of which display advantages and drawbacks for hydrogen storage. It has been hypothesised that their combination by merging two classes of materials showing different sorption behaviour towards hydrogen in the same composite may synergistically combine their desirable properties. As representatives of such composites, palladium nanoparticles, nanoclusters, and single atoms have been encapsulated in a metal-organic framework matrix, embedded, or immobilised in its pores, respectively. In this minireview, we review advances on the understanding and potential applications of the combination of Pd with metal-organic framework matrices through the analysis of the nanocomposite materials’ interaction with hydrogen and sorption properties. 相似文献
We demonstrate a simple technique for the implementation of an all-optical integrator based on a uniform-period fiber Bragg grating (FBG) in reflection that is designed to present a decreasing exponential impulse response. The proposed FBG integrator is readily feasible and can perform close to ideal integration of few-picosecond and subpicosecond pulses. 相似文献
We investigate asymptotically the occurrence of anomalous diffusion and its associated family of statistical evolution equations. Starting from a non-Markovian process à la Langevin we show that the mean probability distribution of the displacement of a particle follows a generalized non-linear Fokker-Planck equation. Thus we show that the anomalous behavior can be linked to a fast fluctuation process with memory from a microscopic dynamics level, and slow fluctuations of the dissipative variable. The general results can be applied to a wide range of physical systems that present a departure from the Brownian regime. 相似文献
This paper is concerned with a quantitative model describing the interaction of three sociological species, termed as owners, criminals and security guards, and denoted by X, Y and Z respectively. In our model, Y is a predator of the species X, and so is Z with respect to Y. Moreover, Z can also be thought of as a predator of X, since this last population is required to bear the costs of maintaining Z.We propose a system of three ordinary differential equations to account for the time evolution of X(t), Y(t) and Z(t) according to our previous assumptions. Out of the various parameters that appear in that system, we select two of them, denoted by H, and h, which are related with the efficiency of the security forces as a control parameter in our discussion. To begin with, we consider the case of large and constant owners population, which allows us to reduce (3), (4) and (5) to a bidimensional system for Y(t) and Z(t). As a preliminary step, this situation is first discussed under the additional assumption that Y(t)+Z(t) is constant. A bifurcation study is then performed in terms of H and h, which shows the key role played by the rate of casualties in Y and Z, that results particularly in a possible onset of bistability. When the previous restriction is dropped, we observe the appearance of oscillatory behaviours in the full two-dimensional system. We finally provide a exploratory study of the complete model (3), (4) and (5), where a number of bifurcations appear as parameter H changes, and the corresponding solutions behaviours are described. 相似文献
The purpose of the present study was to calculate the prevalence and incidence of voice disorders among teaching staff and find out the associated occupational risk factors. A case-control study was performed with 905 teachers, 579 cases and 326 controls; 492 were randomly selected and 413 volunteered. All teachers were asked to fill out a standard questionnaire. Next, a complete laryngeal exam was performed including a general ear, nose, and throat evaluation and videolaryngostroboscopy. The prevalence of voice disorders among teaching staff was 57%. The most prevalent lesions were vocal overstrain (18%), nodular lesions (14%), and hyperfunctional dysphonia (8%). The incidence rate was 3.87 new cases per year per 1000 teachers. Women had organic lesions three times more than men (odds ratio [OR]: 3.52, confidence interval [CI]: 2.04-6.09). However, men had chronic laryngitis three times more than women (OR: 2.93, CI: 1.50-5.71) and functional dysphonia nearly twice more than women (OR: 1.81, CI: 1.21-2.69). We find a significant risk of suffering voice disorders in teachers who smoke daily (OR: 2.31, CI: 1.58-3.37) and who drink several cups of coffee or tea (OR: 1.87, CI: 1.36-2.56). It is advisable to carry out an annual evaluation of all teaching staff on account of the high prevalence of voice disorders among them. 相似文献
We present the synthesis of 4′-amino-4-mercaptobiphenyl (AMB) and its deposition from solution onto Au(111) substrates. The
resulting organic thin films were characterized by contact angle, infrared reflection absorption spectroscopy (IRRAS), X-ray
photoelectron spectroscopy (XPS), and near edge X-ray absorption fine structure (NEXAFS) measurements. It is demonstrated
that the majority of AMB molecules are coupled to the gold surface via S–Au covalent bonds, although only little orientational
order of the AMB layer could be detected by NEXAFS. Furthermore, aromatic imine bonds between AMB and 4-hydroxybenzaldehyde
(HB), 4-carboxybenzaldehyde (CB), 4-methylbenzaldehyde (MB), or 4-(trifluoromethyl) benzaldehyde (TMB) have been successfully
formed. As a result of the limited order, this coupling reaction was incomplete. Nevertheless, the experimental results confirmed
the formation of conjugated aromatic imine bonds. 相似文献
The adsorption of 3,3′-di(methoxycarbonyl)azobenzene (CMA) on Au(111) and on Cu(001) substrates was studied by X-ray absorption
spectroscopy measurements at the C, N, and O K edges. We find the molecules physisorbed in a planar conformation flat on the Au(111) surface. At higher coverages, a molecular
crystal is formed wherein the molecules have the same flat geometry. On Cu(001), additional chemical bonds are formed between
the molecules and the surface via the nitrogen atoms. Here the methyl benzoate moieties are tilted out of the surface plane. 相似文献