With very few exceptions, phthalocyanine dimers are found to be nonfluorescent. We report here the observation of a fluorescent dimer of a tetrasulfonated copper phthalocyanine in ethanol and water. Fluorescence excitation and emission spectra at room temperature and at 77 K are presented. These are consistent with the conventional model of exciton coupling in a cofacial dimer. 相似文献
We have studied the inclusive photon spectra in Upsilon(2S) and Upsilon(3S) decays using a large statistics data sample obtained with the CLEO III detector. We present the most precise measurements of electric dipole (E1) photon transition rates and photon energies for Upsilon(2S) --> gammachi(bJ)(1P) and Upsilon(3S) --> gammachi(bJ)(2P) (J = 0, 1, 2). We measure the rate for a rare E1 transition Upsilon(3S) --> gammachi(b0)(1P) for the first time. We also set upper limits on the rates for the hindered magnetic dipole (M1) transitions to the eta(b)(1S) and eta(b)(2S) states. 相似文献
We propose a generalisation of the congruence subgroup problem for groups acting on rooted trees. Instead of only comparing the profinite completion to that given by level stabilizers, we also compare pro-
$$\mathcal {C}$$
completions of the group, where
$$\mathcal {C}$$
is a pseudo-variety of finite groups. A group acting on a rooted, locally finite tree has the
$$\mathcal {C}$$
-congruence subgroup property (
$$\mathcal {C}$$
-CSP) if its pro-
$$\mathcal {C}$$
completion coincides with the completion with respect to level stabilizers. We give a sufficient condition for a weakly regular branch group to have the
$$\mathcal {C}$$
-CSP. In the case where
$$\mathcal {C}$$
is also closed under extensions (for instance the class of all finite p-groups for some prime p), our sufficient condition is also necessary. We apply the criterion to show that the Basilica group and the GGS-groups with constant defining vector (odd prime relatives of the Basilica group) have the p-CSP. 相似文献
Xenografts are commonly used to test the effect of new drugs on human cancer. However, because of their heterogeneity, analysis of the results is often controversial. Part of the problem originates in the existence of tumor cells at different metabolic stages: from metastatic to necrotic cells, as it happens in real tumors. Imaging mass spectrometry is an excellent solution for the analysis of the results as it yields detailed information not only on the composition of the tissue but also on the distribution of the biomolecules within the tissue. Here, we use imaging mass spectrometry to determine the distribution of phosphatidylcholine (PC), phosphatidylethanolamine (PE), and their plasmanyl- and plasmenylether derivatives (PC-P/O and PE-P/O) in xenografts of five different tumor cell lines: A-549, NCI-H1975, BX-PC3, HT29, and U-87 MG. The results demonstrate that the necrotic areas showed a higher abundance of Na+ adducts and of PC-P/O species, whereas a large abundance of PE-P/O species was found in all the xenografts. Thus, the PC/PC-ether and Na+/K+ ratios may highlight the necrotic areas while an increase on the number of PE-ether species may be pointing to the existence of viable tumor tissues. Furthermore, the existence of important changes in the concentration of Na+ and K+ adducts between different tissues has to be taken into account while interpreting the imaging mass spectrometry results.
3-Acetyl-4-hydroxyphenyl acrylate (AHPA) was synthesized by treating acryloyl chloride with 2,5-dihydroxy acetophenone in the presence of triethylamine at 0 °C. AHPA was polymerized in ethyl methyl ketone (EMK) at 70 °C by free radical polymerization under nitrogen atmosphere using benzoyl peroxide as initiator. The monomer and the polymer were characterized by FT-IR, 1H-NMR and 13C-NMR spectroscopy. The polymer-metal complexes were obtained by the reaction of chloroform solution of poly(AHPA) with aqueous solution of Cu(II)/Ni(II) acetates. The polymer-metal complexes were characterized by FT-IR and the results revealed that the ligands are coordinated through the oxygen of the keto group and oxygen of the phenolic -OH group to the metal ions. The electronic spectra and magnetic moment of polymer-metal complexes showed an distorted octahedral and square planar structure for poly(AHPA)-Ni(II) and poly(AHPA)-Cu(II) complexes respectively. The X-ray diffraction studies revealed that while the polymer was amorphous the polymer-metal complexes were crystalline. The thermal stability and glass transition temperature of the polymer-metal complexes were found to be higher than that of the polymer. 相似文献
A six-step approach to the tetracyclic core of merrilactone A is described that uses an intramolecular Paterno-Büchi photoaddition to install the key oxetane ring. Irradiation of bicyclic enone 16, constructed through cyclopentenone alkylation followed by a domino oxy-/carbopalladation reaction, produces the tetracyclic oxetane 17 in excellent yield, having the core carbon skeleton of the target compound merrilactone A. [reaction: see text] 相似文献
Dynamic viscoelastic measurements were combined with differential scanning calorimetry (DSC) and atomic force microscopy (AFM) analysis to investigate the rheology, phase structure, and morphology of poly(l-lactide) (PLLA), poly(ε-caprolactone) (PCL), poly(d,l-lactide) (PDLLA) with molar composition l-LA/d-LA?=?53:47, and poly(l-lactide-co-ε-caprolactone) (PLAcoCL) with molar composition l-LA/CL?=?67:33. After melt conformation, both copolymers PDLLA and PLAcoCL were found to be amorphous whereas PLLA and PCL presented partial crystallinity. The copolymers and PCL were considered as thermorheologically simple according to the rheological methods employed. Therefore, data from different temperatures could be overlapped by a simple horizontal shift (aT) on elastic modulus, G′, and loss modulus, G′, versus frequency graph, generating the corresponding master curves. Moreover, these master curves showed a dependency of G″≈ω and G′≈ω2 at low frequencies, which is a characteristic of homogeneous melts. For the first time, fundamental viscoelastic parameters, such as entanglement modulus GN0 and reptation time τd, of a PLAcoCL copolymer were obtained and correlated to chain microstructure. PLLA, by contrast, was unexpectedly revealed as a thermorheologically complex liquid according to the failure observed in the superposition of the phase angle (δ) versus the complex modulus (G*); this result suggests that the narrow window for rheological measurements, chosen to be close to the melting point centered at 180 °C thus avoiding thermal degradation, was not sufficient to assure an homogeneous behavior of PLLA melts. The understanding of the melt rheology related to the chain microstructural aspects will help in the understanding of the complex phase structures present in medical devices. 相似文献