Strengthening buildings of stone masonry to resist earthquakes

Stone masonry buildings are common in many areas in the Alpine-Himalayan earthquake zone, and their failure in recent earthquakes has been the cause of many deaths. Poverty and lack of alternatives prevent the replacement of stone masonry with more ductile materials, but the brittleness of unreinforced stone masonry can be considerably reduced by the incorporation of horizontal lacings of timber or reinforced mortar.As part of a joint research project with the Turkish Earthquake Research Institute in Ankara to study low-cost upgrading strategies for rural earthquake protection, full-scale wall elements were subjected to static lateral loading test and dynamic tests on an impulse table. A simple yield-line analysis based on wall overturning was shown to be able to give a useful prediction of the mode of failure and failure load in the static test, and give guidance on the relative performance of unreinforced and reinforced walls in the dynamic test. The results of these tests were used to assess the cost-effectiveness of a large-scale programme of upgrading rural buildings in eastern Turkey.

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Sommario Gli edifici in muratura di pietra sono molto diffusi in ampie zone della regione sismica alpino-himalayana ed il loro crollo ha provocato la perdita di numerose vite umane durante gli ultimi eventi sismici. Spessola poverta' e la mancanza di alternative impediscono la sostituzione della muratura di pietra con materiali piu' duttili: ciononostante il comportamento di tale materiale puo' essere sostanzialmente migliorato incorporando cuciture orizzontali di legno od introducendo elementi metallici nei ricorsi di malta. II progetto di ricerca che si va sviluppando congiuntamente con l'Istituto Turco di Ricerca sui Terremoti di Ankara si propone di individuare una serie di provvedimenti di basso costo per migliorare la qualita' antisimica dell' edilizia rurale. In tale schema sono stati condotti una serie di esperimenti su pannelli murari in scala reale soggetti a carichi statici laterali ed a prove dinamiche su tavola vibrante. Una semplice analisi a rottura basata sul ribaltamento dell'elemento murario si e'dimostrata in grado di fornire accurate previsioni sui meccanismi e sui carichi di rottura nelle prove statiche, e dare utili indicazioni sul comportamento di pannelli semplici e rinforzati sottoposti a prove dinamiche.I risultati di tali prove sono stati utilizzati per una analisi cost-benefici per la definizone di un programma su larga scalla del miglioramento del comportamento sismico di edifici rurali nella Turchia Orientale.

     

Transition Metal Ion-binding Properties of a 14-Membered N2O2S2- Macrobicyclic Ligand

The selective liquid–liquid extraction of various transition metal cations from the aqueous phase to the organic phase was carried out using a 14-membered N₂O₂S₂-macrobicycle. Metal picrates such as Pb²⁺, Co²⁺, Zn²⁺, Ni²⁺,Cu²⁺ and Cd²⁺ were used in this extraction studies. It was found that the ligand showed moderate selectivity towards Pb²⁺ only among the other metals. The extraction constant (log K _ex) was determined to be 13.8 for Pb²⁺ complex.     

Unexpected observation of ion suppression in a liquid chromatography/atmospheric pressure chemical ionization mass spectrometric bioanalytical method

Ion suppression is a well-known phenomenon in electrospray ionization (ESI) mass spectrometry. These suppression effects have been shown to adversely affect the accuracy and precision of quantitative bioanalytical methods using ion spray. Such suppression effects have not been as well defined in atmospheric pressure chemical ionization (APCI) and there is some debate whether these effects actually occur in the ionization process using APCI. Here an example is described where clear ion suppression was observed during studies on a model compound and three metabolites using APCI liquid chromatography/tandem mass spectrometry (LC/MS/MS).     

Stereogenic Propargylic Centers via Base-Mediated Terminal Allene Isomerization

A study of alkali metal amide-mediated isomerizations of terminal allenes is described. The isomerizations of substituted ethenylidenecyclohexanes to form diastereomeric mixtures of terminal alkynes have been conducted to determine factors which may influence the stereochemistry at the newly formed propargylic centers. An initial base screen revealed that potassium N-methylbutylamide (KMBA) exhibits the highest level of equatorial to axial alkyne diastereoselectivity. With the severely hindered terminal allene 26, the use of potassium 3-aminopropylamide is required to effect isomerization. A general synthesis of deuterated terminal allenes has also been achieved, and a mechanistic study using d(2)-allenes 18a,b has revealed the involvement of a propargylic anion in the course of the KMBA-mediated isomerizations.     

Chemiluminescence detection of ATP release from red blood cells upon passage through microbore tubing

A novel approach for the determination of adenosine triphosphate (ATP) released from red blood cells (RBCs) after passage through microbore capillaries is described. ATP is often released from RBCs in vessels and has been linked to the production of nitric oxide, a known vasodilator. The system described here uses a syringe pump to deliver microliter flow rates (5-15 microl min(-1)) of reagent and sample through fused silica capillary tubing of varying dimensions (25-75 microm) to a photomultiplier tube. The released ATP is characterized by the detection of chemiluminescent emission from the luciferin-luciferase reaction. The amount of ATP released is directly proportional to the number of RBCs injected into the system. Results also suggest that the amount of released ATP decreases from 6.9 microM to 1.4 microM as the tubing diameter is increased from 25 microm to 75 microm. An investigation of capillary lengths ranging from 15 to 35 cm resulted in ATP concentrations of 1.5 microM to 2.4 microM being released. Results also indicate that increases in flow rate also induce increased amounts of ATP release. These results are consistent with those of previous systems attempting to model the physiological release of ATP from red blood cells.