THE ADVENT OF CRYPTOLOGY IN THE GAME OF BRIDGE

The surprising discovery that information can be passed both covertly and legally between bridge partners has added a new dimension to the theory of this popular game. In this paper some of the methods are sketched and their cryptologic foundation is described.     

Assimilate transport in grapevines -effect of phloem disruption

Assimilate translocation in mature grapevines (cv. Gewürztraminer and cv. Harslevelü) under field conditions was investigated during the growth season by quantifying individual sugars and organic acids in mature leaves, shoot bark and berries, as affected by girdling the shoot just above the bunches. Tissue was sampled at berry set, pea size, veraison and ripeness stages of the vine. Invertase activity was determined in the shoot bark at ripeness. In the leaves, malic acid concentrations reached lowest levels at pea size, but increased thereafter. Tartaric acid decreased after peaking at pea size stage. Tartaric acid concentrations increased with girdling. Despite the increase in leaf age, sucrose concentrations remained virtually stable during the season, emphasising the importance of mature leaves for nourishing bunches. Girdling resulted in a build‐up of sucrose in the leaves. In the bark, malic and tartaric acid stayed more or less the same during the growth period, but increased above the girdle. As a result of phloem disruption, sucrose also increased. The increase in glucose and tartaric acid is believed to result from catabolic cleavage of sucrose by invertase. Invertase activity was evident in the bark (of mature Harslevelü vines) at ripeness, which may indicate involvement in osmotic adjustments and gradients in the bark/phloem structure. In the berries, malic and tartaric acids reached peak concentrations at pea size. The volume increase during the ripening period, and in the case of malic acid also respiratory loss, resulted in a decrease in organic acid concentration. Malic acid continued to decrease after the initial decline, whereas tartaric acid stayed virtually stable. Girdling had no marked effect on organic acid accumulation in the berries. Sucrose concentrations were low during the first part of the season, but increased thereafter. Sucrose concentrations during ripening increased with girdling, which may represent a concentration effect and/or import from the rest of the vine. Sucrose concentrations (in mature Harslevelü vines) were indeed lower below than above the girdle. Comparison of sucrose concentrations in the leaves, bark and berries showed the existence of a decreasing concentration gradient, in line with the source:sink transport concept. An equally prominent decrease in sucrose:glucose ratio in the berries from the start of the ripening period indicates that vacuolar integrity (compartmentation) was affected in the ripening berry, most probably allowing hydrolysis of sucrose by invertase and decreasing osmotic potential within the berry. The results provide further evidence for the hypothesis of an osmotic gradient driven transport to the berry.     

Phosphorus detection in vitrified bacteria by cryo‐STEM annular dark‐field analysis

Bacterial cells often contain dense granules. Among these, polyphosphate bodies (PPBs) store inorganic phosphate for a variety of essential functions. Identification of PPBs has until now been accomplished by analytical methods that required drying or chemically fixing the cells. These methods entail large electron doses that are incompatible with low‐dose imaging of cryogenic specimens. We show here that Scanning Transmission Electron Microscopy (STEM) of fully hydrated, intact, vitrified bacteria provides a simple means for mapping of phosphorus‐containing dense granules based on quantitative sensitivity of the electron scattering to atomic number. A coarse resolution of the scattering angles distinguishes phosphorus from the abundant lighter atoms: carbon, nitrogen and oxygen. The theoretical basis is similar to Z contrast of materials science. EDX provides a positive identification of phosphorus, but importantly, the method need not involve a more severe electron dose than that required for imaging. The approach should prove useful in general for mapping of heavy elements in cryopreserved specimens when the element identity is known from the biological context.     

MICROORGANISMS AS POTENTIAL SOURCES OF NOVEL DIPHENOL OXIDASE INHIBITORS

Culture filtrates and mycelial homogenates from over 100 microorganisms were tested for their ability to inhibit catecholase and laccase (o- and p-diphenol oxidase) activity using simple, rapid, colorimetric assays in microtiter plates or polarographic assays using an O₂-electrode. Of the organisms screened, 56 produced inhibition of catecholase activity and 34 gave rise to laccase inhibition, with most of the latter group showing inhibition of both enzymes. The role of this enzyme inhibitor system in plant pathogenicity is also discussed.     

ANALYSIS OF COAL DISSOLUTION REACTION ENGINEERING

A phenomenological approach was developed for conversion of coal to pyridine soluble materials with the object of shedding additional light on the reactions taking place during short contact times. The approach was based on a theoretical analysis of many parallel reactions in a complex reacting mixture. The analysis used the concept of lumped species and weighted activation energies to improve on coal liquefaction models. i.e. to remove insensitivity problems for parameters in coal liquefaction models and to answer questions about behaviour of liquefaction reactions in different vessels.     

The effect of post-veraison water deficit on yield components and maturation of irrigated Shiraz (Vitis vinifera L.) in the current and following season

Given their perennial nature, grapevines can respond to deficit irrigation during both the current season as well as during the following season, even though full irrigation may have been restored during that second season. To define the cropping responses involved, three post-veraison irrigation treatments were imposed on spur, mechanically and minimally pruned Shiraz vines that were already receiving restricted water application using Partial Rootzone Drying (PRD). The treatments resulted in the vines receiving 1.25 ML per hectare pre veraison and the three irrigation treatments receiving 1.25, 0.65 and 0 ML of water per hectare in the post-veraison period. Water deficit during the current season reduced berry and bunch weight, and yield. Sugar concentration was reduced, and phenolic concentration increased when less water was applied, but anthocyanin concentration was unaffected. Although irrigation was returned to standard practice (PRD) in the following season, yield was reduced in accordance with deficit irrigation treatments the previous season. This reduction in yield was primarily caused by fewer bunches per vine, which in turn was a direct consequence of fewer shoots per vine (lower budburst). The lower crop load on the vines that had received restricted irrigation post-veraison in the previous season resulted in higher sugar and antho-cyanin concentrations in fruit the following season. Lighter pruning resulted in a greater number of smaller bunches comprising smaller berries. In both seasons the minimal pruning treatment delayed fruit maturity as measured by sugar accumulation. Post-veraison water deficit thus has the potential to impact on both yield and fruit composition during the current season as well as during the subsequent season.     

Evidence for High-Temperature Forms of Zirconium and Tantalum Monocarbides

Evidence has been found which suggests the existence of high-temperature crystalline modifications of both zirconium carbide and tantalum carbide. The high-temperature inversion in zirconium carbide, indicated by a sharp decrease in spectral emisivity, in electrical resistivity, and in density, was reversible. No permanent changes in microhardness or in X-ray diffraction patterns were found after cooling to room temperature. Emissivity measurements showed a hysteresis effect of approximately 400° C for zirconium carbide. A similar, although less sharply defined, effect was noted for tantalum carbide. No such effect was found in solid solutions of these two monocarbides.