Solid state structure and solution conformation of a macrobicyclic cyclophane

X-ray crystallographic structure determination of the macrobicyclic cyclophane L¹ reveals a compact structure involving close edge-to-face approach of aromatic rings; ¹H nmr shows that this is also the solution conformation.     

TUMOR DESTRUCTION IN PHOTODYNAMIC THERAPY

Abstract The effects of photodynamic therapy (PDT) on the tumor microvasculature in the first few hours after treatment was studied at the light microscope (LM) and electron microscope (EM) levels in DBA/2Ha mice bearing SMT-F tumors. Animals received intraperitoneal injections of 10 mg kg⁻ of Photofrin II and 24 h later tumors were treated with 100 J cm⁻² of light (630 nm). Animals were sacrificed and their tumors removed at time 0, 30 min, 1, 2, 4, 8, 16 and 24 h after treatment. The results indicate that the effects of PDT are initially direct destruction of the microfibrils in the subendothelial zone of the tumor capillaries with subsequent tumor cell death secondary to hemorrhage and vascular collapse.     

Generalizations of the projection method with applications to SOR theory for hermitian positive semidefinite linear systems

Summary Ann×n complex matrixB is calledparacontracting if B₂1 and 0x[N(I-B)]Bx₂<x₂. We show that a productB=B _k B _k–1 ...B ₁ ofk paracontracting matrices is semiconvergent and give upper bounds on the subdominant eigenvalue ofB in terms of the subdominant singular values of theB _i 's and in terms of the angles between certain subspaces. Our results here extend earlier results due to Halperin and due to Smith, Solomon and Wagner. We also determine necessary and sufficient conditions forn numbers in the interval [0, 1] to form the spectrum of a product of two orthogonal projections and hence characterize the subdominant eigenvalue of such a product. In the final part of the paper we apply the upper bounds mentioned earlier to provide an estimate on the subdominant eigenvalue of the SOR iteration matrix associated with ann×n hermitian positive semidefinite matrixA none of whose diagonal entries vanish.The work of this author was supported in part by NSF Research Grant No. MCS-8400879     

A simple, practical methodology for routine VSMOW/SLAP normalization of water samples analyzed by continuous flow methods

Normalization of stable isotope data is important for meaningful inter-laboratory comparisons of data, especially for waters where there may be large natural variations in isotope ratios of oxygen and hydrogen. As a result, large, systematic errors may arise in continuous flow applications without correction, whereas normalization to the VSMOW/SLAP scale can facilitate inter-laboratory comparison and can be accomplished by a simple procedure in which secondary laboratory standards, carefully calibrated, are analyzed along with unknown samples. Delta values for these standards, as analyzed, are plotted against the calibrated values and a linear regression is performed. The resulting equation is applied to unknown samples to achieve the normalization. The one-sigma [1sigma] standard deviation for replicate samples by this normalization method using a Finnigan Gasbenchll should be 相似文献