Radioiodination of humic substances via azocoupling with 3-[125I] iodoaniline

A new method is described for radiolabeling humic substances (HS) with iodine radioisotopes. The method radiolabels the electron-rich aromatic moieties of HS with the 3-[125I]iodobenzenediazonium ion via azocoupling. The method uses four steps: (i) 3-aminobenzenetrimethylstannane is synthesized and isolated by using a silica gel column, (ii) 3-[125I]iodoaniline is synthesized and isolated by HPLC, with radiochemical yields of up to 60%, (iii) 3-[125I]iodobenzenediazonium chloride is synthesized, and the reaction mixture from this step is used in step iv to radioiodinate HS with radiochemical yields of up to 95% (with reference to 3-[125I]iodoaniline). The advantage of this method is that it is selective radiolabeling, placing the radiolabel in a specific site (the 3-position of the phenyl ring) within HS molecules, which minimizes unwanted secondary chemical interactions. Investigations of the stability of the radiolabel and the effect of photoreductive dehalogenation showed that there was a negligible release of 125I. The production of radiolabeled HS using this method allows the sensitive detection of HS in laboratory and field studies. In addition, the method offers the possibility of using different iodine radioisotopes simultaneously in investigations using HS.     

Selection of D-amino-acid peptides that bind to Alzheimer's disease amyloid peptide abeta1-42 by mirror image phage display

A mirror image phage display approach was used to identify novel and highly specific ligands for Alzheimer's disease amyloid peptide Abeta(1-42). A randomized 12-mer peptide library presented on M13 phages was screened for peptides with binding affinity for the mirror image of Abeta(1-42). After four rounds of selection and amplification the peptides were enriched with a dominating consensus sequence. The mirror image of the most representative peptide (D-pep) was shown to bind Abeta(1-42) with a dissociation constant in the submicromolar range. Furthermore, in brain tissue sections derived from patients that suffered from Alzheimer's disease, amyloid plaques and leptomeningeal vessels containing Abeta amyloid were stained specifically with a fluorescence-labeled derivative of D-pep. Fibrillar deposits derived from other amyloidosis were not labeled by D-pep. Possible applications of this novel and highly specific Abeta ligand in diagnosis and therapy of Alzheimer's disease are discussed.     

Herstellung von Zellstoffen aus vier verschiedenen Holzarten nach dem ASAM-Verfahren

The ASAM-procedure is very well suited for the pulping of pine, poplar, mossy oak and robinia. The pulps manufactured present very good technological properties, except those of robinia. Maximum strength values are just reached at very low degrees of beating. Emphasis must be given to the high yield and the high brightness of the poplar pulp. Since also the strength values of the poplar pulp is satisfying, the economy of pulp production on the basis of this raw material should be very advantageous. In contrary, robinia may be less suitable for pulp manufacture. For the development of the Hungarian Pulp industry, The ASAM-procedure will be considered as a possible variant.     

The I/O subsystem-a candidate for improvement

A computer system can be partitioned into hardware and the software executing on that hardware. The hardware consists of processor(s), memory, and “everything else”. The “everything else” we generally combine under the umbrella “I/O, whose job it is to manage the availability of information to and from the processor(s) and memory”. That information comes from storage devices, networks, and nonstorage devices. The I/O subsystem is the collection of all three; its influence on performance is a reflection of how well it manages the availability of information to and from all three. The impression today, from both the hardware side and the software side, is that the I/O subsystem can certainly stand improvement. The author considers improvements to the I/O subsystem     

Umweltfreundliche Herstellung von hochwertigen Chemiezellstoffen nach dem ASAM-Verfahren

The ASAM-process is able to produce high quality dissolving pulps from hardwoods as well as from softwoods. Corresponding investigations were conducted with spruce and beech wood. The digestion has to be preceeded by a prehydrolysis state. In the case of hardwoods this will be performed autocatalytically with water at 160–170°C. For sotftwoods 0.5% H₂SO₄ and a temperature at 140–150°C yield the best results. Subsequent ASAM cooking of beech wood yields the best results at 160°C, in spruce pulping a temperature of 170–180°C is more favorable. The resulting Kappa numbers of beech pulps are ranging from 5–10, R₁₀-values from 95–96% and pulp viscosities from 1200–1500 ml/g. Spruce pulps showed Kappa numbers from 12–22 and R₁₀-values vary from 94–94,5% and pulp viscosity from 1200–1500 ml/g. The pulps were TCF-bleached using a O Z P sequence for the beech pulp and a O EOP Z P sequence for the spruce pulp. The resulting brightness exceeded 90% ISO. The viscosity of the fully bleached beech pulp was 1100 ml/g and of the spruce pulp 900 ml/g.     

Changes in the Radiometric sensitivity of SeaWiFS determined from lunar and solar-based measurements

We report on the lunar and solar measurements used to determine the changes in the radiometric sensitivity of the Sea-viewing Wide Field-of-view Sensor (SeaWiFS). Radiometric sensitivity is defined as the output from the instrument (or from one of the instrument bands) per unit spectral radiance at the instrument's input aperture. Knowledge of the long-term repeatability of the SeaWiFS measurements is crucial to maintaining the quality of the ocean scenes derived from measurements by the instrument. For SeaWiFS bands 1-6 (412-670 nm), the change in radiometric sensitivity is less than 0.2% for the period from November 1997 through November 1998. For band 7 (765 nm), the change is approximately 1.5% and for band 8 (865 nm) approximately 5%. The rates of change of bands 7 and 8, which were linear with time for the first eight months of lunar measurements, are now slowing. The scatter in the data points about the trend lines in this analysis is less than 0.3% for all eight SeaWiFS bands. These results are based on monthly measurements of the moon. Daily solar measurements using an onboard diffuser show that the radiometric sensitivities of the SeaWiFS bands have changed smoothly during the time intervals between lunar measurements. Because SeaWiFS measurements have continued past November 1998, the results presented here are considered as a snapshot of the instrument performance as of that date.     

Nonlinear response and thermomechanochemical degradation of a urethane elastomer

We have studied the failure of a urethane elastomer due to cyclic compressive loading, using loading frequencies and specimen sizes for which internal heat generation is an important factor. The eventual failures were generally manifest by internal cracks growing transverse to the loading direction. A variety of experimental analyses indicate that this failure is primarily thermal, in that the temperature rise due to viscous dissipation eventually leads to a melting of the hard segment domains which act to reinforce the material. No strong indication of thermal or thermomechanical bond scission was obtained, although a progressive reduction in the rubbery modulus was noted.     

Alkaline sulfite/anthraquinone pulping of pine wood chips biotreated with Ceriporiopsis subvermispora

Pine wood chips were treated for 30 days with Cemporiopsis subvermispora in 20 dm³ bioreactors. A typical selective biodelignification was observed. The biotreated wood chips and undecayed controls were subjected to modified alkaline sulfite/anthraquinone (ASA) cooking at 170 °C or 175 °C applying varying cooking times ranging from 30 to 270 min. In all cases, the residual lignin content of the pulps prepared from biologically pretreated wood chips was lower than that of the control pulp. With increasing cooking time, however, the differences in kappa number became smaller. Wood chips cooked for a short time required mechanical refining for fiber liberation. A disk‐refining step resulted in pulps with low reject content (0.4%) and high screened yield (56–60%). In this case, the use of biotreated wood chips provided pulps with significantly lower kappa numbers than for the control pulp (71 and 83, respectively). The pulp from biologically pretreated wood fibrillated rapidly, reaching 20° SR in only 38 min beating time in a Jokro mill, while the control pulp required 56 min to reach the same beating degree. Although easier to beat, the biopretreated pulps showed tensile and burst indices similar to those of the control samples. However, their tear indices were always lower. Easier delignification after wood biotreatment was not observed for the reactions performed at long cooking times. Oxygen delignification of biotreated and conventional ASA pulps with low kappa numbers reduced kappa number and improved brightness considerably with the biotreated pulps being favored by a better preservation of viscosity. Copyright © 2004 Society of Chemical Industry     

An automated method for navigation assessment for Earth survey sensors using island targets

An automated method has been developed for performing navigation assessment on satellite-based Earth sensor data. The method utilizes islands as targets which can be readily located in the sensor data and identified with reference locations. The essential elements are an algorithm for classifying the sensor data according to source, a reference catalogue of island locations, and a robust pattern-matching algorithm for island identification. The algorithms were developed and tested for the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), an ocean colour sensor. This method will allow navigation error statistics to be automatically generated for large numbers of points, supporting analysis over large spatial and temporal ranges.