Acid neutralisation capacity and hydration behaviour of incineration bottom ash-Portland cement mixtures

The present paper deals with the use of incineration bottom ash in cementitious systems. The results of the physical-mechanical characterisation of the solidified products were discussed elsewhere, while the present work focuses on the acid neutralisation capacity (ANC) of the investigated mixtures as a means to evaluate the type of hydration products and their relative amounts in the solid matrix. The approach consists of differential acid neutralisation analysis, which was validated using traditional X-ray diffraction (XRD) methods.     

Impacts of gate structure on dynamic threshold SOI nMOSFETs

The effects of different substrate-contact structures (T-gate and H-gate) dynamic threshold voltage silicon-on-insulator (SOI) nMOSFETs (DTMOS) have been investigated. It is found that H-gate structure devices have higher driving current than T-gate under DTMOS-mode operation. This is because H-gate SOI devices have larger body effect factor (/spl gamma/), inducing a lager reduction of threshold voltage. Besides, it is found that drain-induced-barrier-lowering (DIBL) is dramatically reduced for both T-gate and H-gate structure devices when devices are operated under DTMOS-mode.     

Volume scattering of distributed microbubbles and its influence on blood flow estimation

In recent years, microbubble contrast agents have become a potential adjunct in Doppler ultrasound diagnosis. In this paper, we show that volume scattering makes the effective band in Doppler spectrum shift downward after injection of microbubbles. Because the insonified volume comprises a collection of distributed microbubbles, the statistical properties such as the autocorrelation function and ensemble average power spectrum of the echoes from a collection of distributed microbubbles were derived first. It can be observed that, beyond a critical frequency, the theoretical volume backscattering cross section derived from the ensemble average power spectrum of microbubbles decreases with frequency. On the contrary, the volume backscattering cross section of red cells increases with frequency. Using two-dimensional (2-D) Fourier transform, the variation in Doppler spectrum caused by different volume backscattering cross section can be demonstrated, and the consequential downward shifts of the estimated Doppler parameters (e.g., the mean and maximum Doppler shifts, and the variance of Doppler power spectrum) after microbubble injection are shown. In addition, it can be observed that the variation gets larger as the transmitted bandwidth increases. And, the variations in Doppler parameters estimated with experimental data are presented to verify the theoretical deviations.     

A family of ductile intermetallic compounds

Stoichiometric intermetallic compounds have always been touted for their attractive chemical, physical, electrical, magnetic and mechanical properties, but few practical uses have materialized because they are brittle at room temperature. Here we report on a large family of fully ordered, stoichiometric binary rare-earth intermetallic compounds with high ductility at room temperature. Although conventional wisdom calls for special conditions, such as non-stoichiometry, metastable disorder or doping to achieve some ductility in intermetallic compounds at room temperature, none of these is required in these unique B2 rare-earth compounds. Ab initio calculations of YAg, YCu and NiAl crystal defect energies support the observed deformation modes of these intermetallics.     

Enzyme-aided investigation of the substituent distribution in cationic potato amylopectin starch

The distribution of substituents along the polymer chain in cationic potato amylopectin starch, modified in solution, granular slurry, or dry state, was investigated. The starch derivatives were successively hydrolyzed by different enzymes, followed by characterization of the hydrolysis products obtained by means of electrospray mass spectrometry (ESI-MS) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). ESI-MS and MALDI-MS were proved to be appropriate techniques for identification of the substituted hydrolysis products, for which there are no standard compounds available. No highly substituted oligomers were found in the hydrolysates, which was taken as an indication of a more or less homogeneous distribution of cationic groups in the amylopectin molecules. Furthermore, from the results obtained it was suggested that the enzymes cleave glucosidic linkages only between unsubstituted glucose units and, preferentially, linkages in sequences containing more than two adjacent unsubstituted units. The determination of the amount of unsubstituted glucose produced from every successive hydrolysis step revealed slight differences between the different starch samples with respect to the homogeneity of the substitution pattern. Among the three samples under investigation, starch cationized in solution was found to have the most and dry-cationized starch the least homogeneous distribution of substituents.     

Influence of genetic type, live weight at slaughter and carcass fatness on fatty acid composition of subcutaneous adipose tissue of raw ham in the heavy pig

The study aimed to assess some quality traits of the subcutaneous adipose tissue of raw ham for Parma production, obtained from 56 “traditional” Landrace × Large White (L × LW) and 56 Cotswold commercial hybrid (CH) pigs reared in the same conditions and slaughtered at an average live weight (l.w.) of about 165 kg. Further, the relationships between lipid composition, l.w. and carcass fatness were studied. Compared to the CH, the fatty tissue of L × LW pigs showed a lower water (6.33% vs. 7.35%, P < 0.01) and a higher lipid (91.18% vs. 90.18%, P < 0.01) content. CH lipids had higher polyunsaturated fatty acids (16.53% vs. 13.75%, P < 0.01), and smaller saturated fatty acids (38.20% vs. 40.26%, P < 0.01) content and a higher iodine value (69.69 vs. 65.22, P < 0.01). An increased slaughter weight was associated with a lower degree of lipid unsaturation, but only the lowest weight class (<160 kg) showed a significant difference compared to the other two classes (⩾160 < 170 and ⩾170 kg). Regardless of genetic type or l.w. class, an increase in backfat thickness is associated with an increase in saturated and monounsaturated fatty acids and a remarkable reduction in polyunsaturated content.     

In vivo monitoring of fluorescent nanosphere delivery in anesthetized rats using an implantable fiber-optic microprobe

An implantable needle-type fiber-optic microprobe was constructed to monitor in vivo fluorescent substances in anesthetized rats. This fiber-optic microprobe was composed of coaxial optical fibers that were catheterized using a thin-wall tube of stainless steel (o.d. approximately 400 microm; i.d. approximately 300 microm). When the fiber-optic microprobe was placed in solutions containing various concentrations of fluorescent nanospheres (20 nm), either in the presence or in the absence of 10% Lipofundin acting as an optical phantom, we observed nanosphere concentration-dependent responses of the fluorescence intensity. The microprobe was then implanted into the livers and brains of anesthetized rats to monitor the in situ extravasation of preadministered fluorescent nanospheres from vasculature following the hepatic and cerebral ischemic insults. Both types of ischemic insults showed immediate increases in fluorescent intensities when 20-nm fluorescent nanosphere were administered, but neither ischemic insult induces such an increase when we administered 1000-nm fluorescent nanospheres. Additional experiments can be performed to further narrow the size range of the increase in blood vessel permeability following ischemic insult; such "size" information may be valuable when formulating drugs for optimal local delivery. Although a wide variety of fluorescent substances are used intensively for in vitro biological studies, the in vivo and in situ monitoring of these substances is studied much less often, probably because of difficulties in the efficient assembly of miniaturized fiber optics to detect the relatively weak fluorescence signal arising within such a turbid medium as tissue. To our knowledge, the use of our implantable fiber-optic microprobe is the first minimally invasive technique capable of investigating the "size window" of vascular permeability for the in vivo delivery of nanospheres in both ischemic livers and brains.     

A framework for optimising the radiographic technique in digital X-ray imaging

The transition to digital radiology has provided new opportunities for improved image quality, made possible by the superior detective quantum efficiency and post-processing capabilities of new imaging systems, and advanced imaging applications, made possible by rapid digital image acquisition. However, this transition has taken place largely without optimising the radiographic technique used to acquire the images. This paper proposes a framework for optimising the acquisition of digital X-ray images. The proposed approach is based on the signal and noise characteristics of the digital images and the applied exposure. Signal is defined, based on the clinical task involved in an imaging application, as the difference between the detector signal with and without a target present against a representative background. Noise is determined from the noise properties of uniformly acquired images of the background, taking into consideration the absorption properties of the detector. Incident exposure is estimated or otherwise measured free in air, and converted to dose. The main figure of merit (FOM) for optimisation is defined as the signal-difference-to-noise ratio (SdNR) squared per unit exposure or (more preferably) dose. This paper highlights three specific technique optimisation studies that used this approach to optimise the radiographic technique for digital chest and breast applications. In the first study, which was focused on chest radiography with a CsI flat-panel detector, a range of kV(p) (50-150) and filtration (Z = 13-82) were examined in terms of their associated FOM as well as soft tissue to bone contrast, a factor of importance in digital chest radiography. The results indicated that additive Cu filtration can improve image quality. A second study in digital mammography using a selenium direct flat-panel detector indicated improved SdNR per unit exposure with the use of a tungsten target and a rhodium filter than conventional molybdenum target/molybdenum filter techniques. Finally, a third study focusing on cone-beam computed tomography of the breast using a CsI flat-panel detector indicated that high Z filtration of a tungsten target X-ray beam can notably improve the signal and noise characteristics of the image. The general findings highlight the fact that the techniques that are conventionally assumed to be optimum may need to be revisited for digital radiography.     

Integral equation approach for 3D multiple-crack problems

In this paper, a traction integral equation containing no hypersingular integrals is presented to study the interaction of multiple cracks in an infinite elastic medium. 8-node quadratic quadrilateral elements are used to discretize general crack surfaces, and special crack tip elements are employed along surface boundaries to model the variation of displacements near the crack fronts. Thus, the method possesses the merits of the traction integral equation without hypersingular integrals and those of the special crack tip elements for modeling variation of displacements near the crack tips. The stress intensity factors at the crack front are evaluated using one point formulation and the results are compared with available solutions.     

Kinetics study of Bungarus fasciatus venom acetylcholinesterase immobilised on a Langmuir-Blodgett proteo-glycolipidic bilayer

This study deals with the kinetics properties of an enzyme immobilised in a defined orientation in a biomimetic environment. For this purpose, acetylcholinesterase (AChE) was captured at the surface of a nanostructured proteo-glycolipidic Langmuir-Blodgett film through specific recognition by a noninhibitor monoclonal antibody (IgG) inserted in a neoglycolipid bilayer. Modelling of this molecular assembly provided a plausible interpretation of the functional orientation of the enzyme. The AChE activity being stable for several weeks, the enzyme kinetics were investigated, and fitted perfectly with heterogeneous biocatalytic behaviour representative of cellular enzymatic catalysis. The AChE-IgG-glycolipid nanostructure was directly interfaced with an efficient optical device. Such an association, leading to an intimate contact between the nanostructure and the biochemical signal transducer, gives direct access to the intrinsic AChE behaviour. This study thus demonstrates the potential for direct investigation of the kinetic behaviour of an immobilised enzyme on a lipid bilayer through an efficient transduction system.