Circular dichroism measurements of benzyl L-aspartate–nitrobenzyl L-aspartate copolymers and their use in detecting and characterizing preferred polymer conformations

We have examined the nature of the circular dichroism band at 330 mμ for a series of copolymers of β-p-nitrobenzyl L -aspartate with β-benzyl L -aspartate. The circular dichroism band arises from an electronic transition in the nitroaromatic group. In order to interpret the effect quantitatively, we employed a simplified statistical treatment and curve fitting for six copolymers. Both approaches gave consistent results, which indicates that the dichroism comes from pairwise interactions between two nitrobenzyl groups. We constructed a molecular model that meets the constraints and requirements of the analyses developed in this paper. In this model, it is proposed that the main chain forms a right-handed α-helix and that nitrobenzyl groups separated by four residues interact with each other.     

Decomposition of cellulose in soils

1. Cellulose decomposition in forest and orchard soils was investigated by studying the breakdown of boiled and washed cellophane in the soils and in vitro. Decomposition occurred from quick to slow in the order: orchard on clay soil, forest on clay soil, forest on sandy loam, and in the latter in the order: calcareous mull, acid mull and mor. 2. In the different forest soils which were investigated the rate of decomposition was parallel to their water capacity. It slowed down considerably when the water content of the soil decreased, especially after the wilting point was reached. 3. Of the fungi isolated from these soils, those from orchard soil — 5% to 50%Fusarium spp. — were among the fastest decomposers of cellulose. This agrees with, and may explain the high rate of decomposition in orchard soil. 4. Decomposition in pure culture is quicker than in soil. As filtersterilized soil extract checked the decomposition in pure culture, but heat-sterilized soil extract did not, an extractable but heat-sensitive substance may be one retarding factor.     

A combined micro-and semi-micro colorimetric determination of long-chain fatty acids from plant cutin

Summary Re-examination of the colorimetric fatty acid determination with copper nitrate, followed by complex formation with DIECA has shown that the method is not reliable if applied as described by Duncombe (1962, 1963): The Cu concentration is too high, the DIECA concentration much too low and the wavelength chosen (440 m) is suitable only for very low fatty acid concentrations.According to the results reported here the following alterations have to be adopted: The concentration of the copper nitrate solution should be 3%, a 0.5% solution of DIECA in butanol has to be used and measurements should be done at 492 m. The method described here offers the opportunity to determine fatty acid concentrations in the semi-micro range by measuring the filtered chloroform phase directly at 691 m, covering a range between 175 g/ml to 1.2 mg/ml. If the concentration turns out to be lower than 200 g F. A./ml, the same sample can be used for a micro-determination (up to 200 g/ml) at 492 m, after formation of the yellowish-brown complex by addition of 0.1 ml 0.5% butanolic DIECA solution to 1.0 ml of the chloroform phase.The method has been applied to determine the amount of free F. A. in cutin layers and cutin powder, revealing that the latter contains 5.6 times more free F. A. than the intact material. The free F. A. within the polymer seem to serve as interconnections for the main units of the cutin polylipid.     

Right Internal Mammary Artery Implantation into Right Ventricular Myocardium for Revascularization of the Entire Heart: Experimental Data and Preliminary Report

The left internal mammary artery implant combined with epicardiectomy and free omental graft provides three extra-coronary sources of blood. This operation tested in dogs with 92% main-stem occlusion of three coronary arteries protected 75% of the animals. Applied clinically in over 100 patients, the operation resulted in 90% improvement. To obtain complete myocardial revascularization, the right internal mammary artery has been used as a fourth source of extra-coronary blood. In 57 animals, the right internal mammary arteries were implanted into the anterior walls of the right ventricle; in 80% this vessel formed anastomoses with the right coronary tree, and in 65% with the right and left coronary arteriolar systems. Six patients are described who underwent right internal mammary artery implantation; five of these in addition had the combined operation of left internal mammary artery implant, epicardiectomy and free omental graft. All patients had completely blocked right coronary arteries; in addition, five had advanced disease of the left coronary arterial tree.     

Formation and function of compression wood in gymnosperms

Westing, Arthur H. (Middlebury Coll., Vt.). 1965.Formation and function of compression wood in gymnosperms. Bot. Rev. 31: 381–480 A review with ca. 575 references. The world literature pertaining to the biology of compression wood (Rotholz; reaction wood) is evaluated critically. Compression wood is a geotropic reaction to an inertial force and is peculiar to the Coniferales, Ginkgoales, and Taxales. It is formed by the cambium (or cambial derivatives) of the lower side of inclined stems and branches, where it expandsin situ thereby tending to right the former and maintain (or restore) the inherent angle of the latter. Compression wood is stimulated to form by applications of indoleacetic acid, but under natural conditions is interpreted to result from an increased sensitization of cells on the lower side to an insignificantly changed level of endogenous auxin. A theoretical model of the perception (susception) mechanism is advanced. The mechanics of righting is discussed and the forces involved are estimated. Frequent reference is made to other geotropic phenomena of the higher plants, particularly to tension wood, the analogue of compression wood in the arborescent Dicotyledoneae. Much pertaining to the perception, formation, and function of compression wood remains to be elucidated