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Organisationseinheit der BAM
Under the auspices of the Organic Analysis Working Group (OAWG) of the Comité Consultatif pour la Quantité de Matière (CCQM) a key comparison, CCQM K55.b, was coordinated by the Bureau International des Poids et Mesures (BIPM) in 2010/2011. Nineteen national measurement institutes and the BIPM participated. Participants were required to assign the mass fraction of aldrin present as the main component in the comparison sample for CCQM-K55.b which consisted of technical grade aldrin obtained from the National Measurement Institute Australia that had been subject to serial recrystallization and drying prior to sub-division into the units supplied for the comparison.
Aldrin was selected to be representative of the performance of a laboratory's measurement capability for the purity assignment of organic compounds of medium structural complexity [molar mass range 300 Da to 500 Da] and low polarity (pKOW < -2) for which related structure impurities can be quantified by capillary gas phase chromatography (GC).
The key comparison reference value (KCRV) for the aldrin content of the material was 950.8 mg/g with a combined standard uncertainty of 0.85 mg/g. The KCRV was assigned by combination of KCRVs assigned by consensus from participant results for each orthogonal impurity class. The relative expanded uncertainties reported by laboratories having results consistent with the KCRV ranged from 0.3% to 0.6% using a mass balance approach and 0.5% to 1% using a qNMR method.
The major analytical challenge posed by the material proved to be the detection and quantification of a significant amount of oligomeric organic material within the sample and most participants relying on a mass balance approach displayed a positive bias relative to the KCRV (overestimation of aldrin content) in excess of 10 mg/g due to not having adequate procedures in place to detect and quantify the non-volatile content–specifically the non-volatile organics content–of the comparison sample.
There was in general excellent agreement between participants in the identification and the quantification of the total and individual related structure impurities, water content and the residual solvent content of the sample.
The comparison demonstrated the utility of 1H NMR as an independent method for quantitative analysis of high purity compounds. In discussion of the participant results it was noted that while several had access to qNMR estimates for the aldrin content that were inconsistent with their mass balance determination they decided to accept the mass balance result and assumed a hidden bias in their NMR data. By contrast, laboratories that placed greater confidence in their qNMR result were able to resolve the discrepancy through additional studies that provided evidence of the presence of non-volatile organic impurity at the requisite level to bring their mass balance and qNMR estimates into agreement.
Gastric cancer (GC) is the 3rd deadliest cancer worldwide, due to limited treatment options and late diagnosis. Human epidermal growth factor receptor-2 (HER2) is overexpressed in similar to 20% of GC cases and anti-HER2 antibody trastuzumab in combination with conventional chemotherapy, is recognized as standard therapy for HER2-positive metastatic GC. This strategy improves GC patients' survival by 2-3 months, however its optimal results in breast cancer indicate that GC survival may be improved. A new photoimmunoconjugate was developed by conjugating a porphyrin with trastuzumab (Trast: Porph) for targeted photodynamic therapy in HER2-positive GC. Using mass spectrometry analysis, the lysine residues in the trastuzumab structure most prone for porphyrin conjugation were mapped. The in vitro data demonstrates that Trast: Porph specifically binds to HER2-positive cells, accumulates intracellularly, co-localizes with lysosomal marker LAMP1, and induces massive HER2-positive cell death upon cellular irradiation. The high selectivity and cytotoxicity of Trast: Porph based photoimmunotherapy is confirmed in vivo in comparison with trastuzumab alone, using nude mice xenografted with a HER2-positive GC cell line. In the setting of human disease, these data suggest that repetitive cycles of Trast: Porph photoimmunotherapy may be used as an improved treatment strategy in HER2-positive GC patients.
The determination of the mass fractions of bromide, sulfate, and lead as well as the isotopic composition of the lead (expressed as the molar mass and the amount fractions of all four stable lead isotopes) in an aqueous solution of sodium chloride with a mass fraction of 0.15 g/g was the subject of this comparison. Even though the mass fractions ranged from 3 μg/g (bromide) to 50 ng/g (lead), almost all results reported agreed with the according KCRVs.
The influence of the surface roughness of pearlitic grey cast iron discs on the formation of tribofilms and the evolution of the friction coefficient during a ring on disc tribotest with the addition of magnetite and magnetite–graphite nanopowders as interfacial media was investigated. The roughness parameters of the cast iron discs were varied by electro discharge machining (EDM) and grinding processes, producing four distinct surface roughness conditions. The evolution of the friction coefficient, however, did not reach the steady state for most of the samples and the role of the surface roughness on the friction coefficient could not be identified. Focused ion beam (FIB) microscopy on the cast iron discs was carried out to investigate the microstructure of the discs near the tribosurface. These results showed that the EDM process not only varied the surface roughness, but also changed the microstructure of the cast iron discs, promoting the incipient fusion of the cast iron surface, with the formation of ridges and casting defects (pores). As a result, a layer of rapidly solidified metal with a dendritic microstructure was formed near to the surface of the EDMed discs.
Thermal restraint effects on the fire resistance of steel and composite steel and concrete columns
(2009)
The composite steel and concrete columns are known to have enhanced fire behaviour when compared with bare steel columns. However there are still aspects that must be clarified, as the influence of the building surrounding structure on the fire resistance of the columns. In this paper, the results of fire resistance tests on partially encased steel columns carried out with two different experimental systems are compared. In one of the experimental systems, the building surrounding structure is materialised by a steel restraining frame, and in the other is performed by the so-called substructuring method. Due to the concept of hybrid substructuring, the entire building is decomposed in two parts: one is represented by the building element under test, whereas the remaining building is simulated numerically in a computer. The main conclusion drawn from this work was that the surrounding structure has a major influence in the development of axial forces in the test columns. Moreover, it was observed that the higher the non-dimensional axial restraint ratio the lower the critical time of the columns.
Damage and strength reduction of a high performance concrete due to thermomechanical stresses
(2008)
Most of the previous studies on reinforced concrete columns with elastically restrained thermal elongation were carried out on square, rectangular or ‘+’-shaped cross sections. The fire resistance of these columns is probably more compromised than in circular columns due to the phenomenon of concrete detachment in the corners of the cross-section. In order to examine the influence of several parameters on the behaviour in fire of circular reinforced concrete columns with restrained thermal elongation, several fire resistance tests were carried out. The parameters tested were load, restraint level, slenderness of the column and the longitudinal reinforcement ratio. In the fire resistance tests the specimens were exposed to the ISO 834 Standard fire curve and the critical time and temperature and failure modes were determined. The test results mainly indicated that the spalling phenomenon may also occur in circular columns and so reducing its fire resistance. The restrained level might not so much relevant concerning the fire resistance of circular reinforced concrete columns.
Most of the previous studies on reinforced concrete columns with elastically restrained thermal elongation were carried out on square, rectangular or '+'-shaped cross sections. The number of fire resistance tests on circular reinforced concrete columns with elastically restrained thermal elongation is still very small. In order to examine the influence of several parameters on the behaviour in fire of this type of columns several fire resistance tests were carried out. The parameters tested were the load and restraint level, slenderness of the column and longitudinal reinforcement ratio. In the fire resistance tests the specimens were exposed to the ISO 834 standard fire curve and the critical time (fire resistance) and temperature and failure modes were determined. The test results showed that the spalling phenomenon may occur in circular columns and so reducing its fire resistance. The increasing of the load level led to a reduction while the increasing of the longitudinal reinforcement ratio or the decreasing of the slenderness of the columns led to an increasing of their fire resistance. The restraint level might not be much relevant on the fire resistance of circular reinforced concrete columns.