Mechano-chemischer abbau bei der schwingmahlung von poly(ε-caprolactam) in gegenwart von sebacoylchlorid und nachfolgende polykondensation mit aromatischen diaminen

Mechano-chemical degradation of poly(ε-caprolactam) {poly[imino(1-oxohexamethylene)]} in the presence of sebacoyl chloride, carried out by vibratory milling, gave polyamide acid chlorides. Subsequently, these products, also by vibratory milling, were condensed with p-phenylenediamine to obtain polymers with aromatic amino groups which by diazotation and coupling reaction were transformed into coloured polymers. The use of some specially selected coupling components (i.e. containing itself primary amino groups) allowed to regulate the colour intensity of the final product when the diazotation and coupling reaction was carried out gradually.     

Heterogeneity of Borrelia burgdorferi sensu lato demonstrated by an ospA-type-specific PCR in synovial fluid from patients with Lyme arthritis

Borrelia burgdorferi sensu lato, the etiological agent of Lyme borreliosis, has been divided into three genospecies: B. burgdorferi sensu stricto (OspA-type 1), B. afzelii (OspA-type 2) and B. garinii (OspA-type 3–7). Whereas in Europe B. afzelii (OspA-type 2) is predominant among human skin isolates and B. garinii (OspA-type 3–7) among human CSF isolates, some previous serological studies suggested that Lyme arthritis is also associated with B. burgdorferi sensu stricto in Europe. In the present study we designed ospA type-specific PCRs and identified four different ospA types associated with Lyme arthritis. Our study group consisted of 20 patients with positive serology (ELISA and immunoblotting) and clinical criteria for Lyme arthritis. B. burgdorferi DNA was detected in 13 patients and in none of 10 control patients from synovial fluid. We identified ospA-type 1 (26.6%), ospA-type 2 (33.3%), ospA-type 4 (6.6%) and ospA-type 5 (33.3%). Our conclusion is that in Europe B. burgdorferi sensu lato strains causing Lyme arthritis are considerably heterogeneous and that there is no prevalence of certain genospecies or OspA-types among this strains. Received: 14 May 1998     

Probing the supramolecular features via π–π interaction of a di-iminopyrene-di-benzo-18-crown-6-ether compound: experimental and theoretical study

A novel DPyDB-C N-18C6 compound was synthesised by linking a pyrene moiety to each phenyl group of dibenzo-18-crown-6-ether, the crown ether, through –HC N– bonds and characterized by FTIR, ¹H-NMR, ¹³C-NMR, TGA, and DSC techniques. The quantitative ¹³C-NMR analysis revealed the presence of two position isomers. The electronic structure of the DPyDB-C N-18C6 molecule was characterized by UV-vis and fluorescence spectroscopies in four solvents with different polarities to observe particular behavior of isomers, as well as to demonstrate a possible non-bonding chemical association (such as ground- and excited-state associations, namely, to probe if there were forming dimers/excimers). The interpretation of the electronic structure was realized through QM calculations. The TD-CAM-B3LYP functional, at the 6-311+G(d,p) basis set, indicated the presence of predominant π → π* and mixed π → π* + n → π* transitions, in line with the UV-vis experimental data. Even though DPyDB-C N-18C6 computational studies revealed a π-extended conjugation effect with predominantly π → π* transitions, thorough fluorescence analysis was observed a weak emission, as an effect of PET and ACQ. In particular, the WAXD analysis of powder and thin films obtained from n-hexane, 1,2-dichloroethane, and ethanol indicated an amorphous organization, whereas from toluene a smectic ordering was obtained. These results were correlated with MD simulation, and it was observed that the molecular geometry of DPyDB-C N-18C6 molecule played a defining role in the pyrene stacking arrangement.

Herein, we report the formation of a potential supramolecular arrangement mediated by inter- and intra-molecular interactions between di-iminopyrene-dibenzo-18-crown-6-ether molecules.     

Diagnosis of renal metanephric adenoma: relevance of immunohistochemistry and biopsy

Most renal tumors of the adult are carcinomas. Their treatment is surgical, consisting of limited excision or nephrectomy. In some instances, biopsy of the tumor can be performed in order to adapt treatment. We report the case of a 45 year-old woman presenting with renal tumor. A biopsy of the mass showed a metanephric adenoma. No surgical excision was performed because of the benignity of this tumor. Here we develop the interest of immunohistochemistry for differential diagnosis of metanephric adenoma and other "basophilic small cell tumors" of the kidney. We also put the stress on the growing role of biopsy of renal tumor allowing optimal treatment.     

A comparison of hydrogen release kinetics from 5- and 6-membered 1,2-BN-cycloalkanes

The reaction order and Arrhenius activation parameters for spontaneous hydrogen release from cyclic amine boranes, i.e., BN-cycloalkanes, were determined for 1,2-BN-cyclohexane (1) and 3-methyl-1,2-BN-cyclopentane (2) in tetraglyme. Computational analysis identified a mechanism involving catalytic substrate activation by a ring-opened form of 1 or 2 as being consistent with experimental observations.

The reaction order and Arrhenius activation parameters for spontaneous hydrogen release from cyclic amine boranes, i.e., BN-cycloalkanes, were determined for 1,2-BN-cyclohexane (1) and 3-methyl-1,2-BN-cyclopentane (2) in tetraglyme.

Amine boranes have long been targeted as a promising class of potential hydrogen storage materials.¹ The simplest amine borane, ammonia borane (H₃NBH₃), has attracted significant attention by virtue of its particularly high gravimetric hydrogen density (19.6 wt% H₂).² Thermal decomposition of ammonia borane to release H₂, however, frequently generates mixtures of oligomeric and polymeric products, which in turn can complicate efforts to regenerate the fully saturated starting material for reuse.¹ Extensive studies of variously substituted amine boranes have thus been conducted in the interest of identifying a system that releases H₂ more selectively.^3,4Our approach in this regard has been to incorporate the amine borane H₂NBH₂ unit into carbocyclic structures to form saturated carbon–boron–nitrogen (CBN) heterocycles.⁵ We have previously discovered that two of these compounds, 1,2-BN-cyclohexane (1)⁶ and its constitutional isomer 3-methyl-1,2-BN-cyclopentane (2)⁷ undergo full, thermally-induced BN-dehydrogenation to afford only the trimeric products 3 and 4 through the intermediacy of monomeric BN-“cycloalkene” species 1–H₂ (ref. 8) and 2–H₂, respectively (Scheme 1).Open in a separate windowScheme 1Selective thermal decomposition of 1 and 2 to trimers 3 and 4, respectively.While 1 and 2 appeared to exhibit the same general dehydrogenation selectivity, in subsequent experiments using neat material, we observed an intriguing difference in the thermal stability of these compounds. Specifically, thermo-gravimetric analysis-mass spectrometry (TGA-MS) revealed significant loss of H₂ from 2 initiated at ∼50 °C,⁹ but an analogous measure of decomposition of 1 occurred only upon heating to ∼70 °C (Fig. S2; see also Fig. S3^† for the temperature-programmed desorption-mass spectrometry (TPD-MS) of 1). Thus, of the two materials, only 1 would meet the minimum requirement for operational stability set by the US Department of Energy''s Hydrogen and Fuel Cells Program for on-board vehicular applications.¹⁰A mechanistic investigation of the origin of this dichotomy of dehydrogenation reactivity would aid in the design of better amine borane-based hydrogen storage materials and add to our fundamental understanding of the reactivity of amine boranes. Herein, we provide a solution-phase kinetic analysis of initial H₂ release from 1 and 2 using ReactIR. The kinetic data establish a second-order decomposition pathway that is in agreement with a computationally-derived mechanistic model. We also provide evidence that the ring strain associated with the 5-membered heterocycle 2 is ultimately responsible for its faster decomposition rates.^11,12The reaction order for the first step of dehydrogenation of 1 and 2 was determined using the initial rates method. Both 1 and 2 exhibit a characteristic IR frequency at 1600 cm⁻¹ (attributed to an N–H bending mode); the disappearance of starting material can thus be readily monitored in situ by ReactIR.¹³ The initial concentrations ([ ]₀) of either 1 or 2 in a tetraglyme solution at 140 °C were varied between 0.560 M and 1.283 M, and initial rates (r_i) were estimated based on linear regression of the respective portions of the substrate disappearance trends representing up to 20% conversion. As shown in Fig. 1, a linear fit of ln(r_i) vs. ln([ ]₀) yielded a slope of 2 for both 1 and 2, indicating the rate of initial H₂ loss from each follows a second-order concentration dependence.¹⁴Open in a separate windowFig. 1Abbreviated substrate disappearance trends measured at 140 °C for various initial concentrations of 1 (A) and 2 (C), and reaction order determination by the initial rates method for 1 (B) and 2 (D).A subsequent Arrhenius analysis was enabled by maintaining a constant initial concentration of 0.742 M, and varying the reaction temperature from 120–160 °C for 1 and from 100–160 °C for 2. As shown in Fig. 2). (Extrapolation to lower temperatures, e.g., 50 °C, reveals an even wider gap of approximately three orders of magnitude.) It thus appears that enthalpic factors, as represented by E_a values,¹⁵ are primarily responsible for the faster kinetics of H₂ release from 2 relative to those of 1.Experimentally determined activation energies (E_a) and pre-exponential factors (A) for 1 and 2 based on Arrhenius analyses

Mechanochemische Synthesen durch Polykondensation mit Polyestern als Grundsubstanz, 3. Einige kinetische Aspekte der Mechanochemischen Polykondensation durch Schwingmahlung des Poly(oxyäthylenoxyterephthaloyl)s mit aliphatischen Diaminen

The kinetics and the mechanism of the mechanochemical polycondensation process of poly(oxyethyleneoxyterephthaloyl) [poly(ethylene terephthalate)] with aliphatic diamines (ethylene- and hexamethylenediamine) were studied. First order kinetics was found and in addition the fact that a very small thermal activation energy is needed and that the diamines can react as radical acceptors.     

Specifics of therapy of tubal infertility in patients with endometriosis

Our purpose was to define the best way of treating tubal infertility caused by endometriosis. We have studied 24 patients with tubal infertility caused by endometriosis; the etiology has been laparoscopically established in the 2nd Clinic of Obstetrics and Gynecology Ia?i. The endometriosis score (r-AFS) was used to establish the therapy. We performed laparoscopic treatment when endometriosis was visible. Postoperative medical therapy (Diphereline, 3 months) was indicated; patients with ,,unpigmented endometriosis" received the same medical therapy. The rate of pregnancies in patients that had benefit of combined therapy: surgical and medical (n=9) was superior (44.4%) to that obtained in patients that were only surgical treated (n=15): 26.6% (Spearman correlation--0.6595, p < 0.0012). Endometriosis is an important etiological factor in female infertility. The pathway is mechanic as well as chemical and it justifies the combined therapy. There are better results, as fertility prognosis in patients with endometriosis that receive both, surgical and medical therapy.