Resonance Raman and DFT studies of tetra-tert-butyl porphine: Assignment of strongly enhanced distortion modes in a ruffled porphyrin

The free-base form of tetra-tert-butyl porphine (TtBP), which has extremely bulky meso substituents, is severely distorted from planarity, with a ruffling angle of 65.5degrees. The resonance Raman spectrum of TtBP (lambda(ex) = 457.9 nm) and its d(2), d(8), and d(10) isotopomers have been recorded, and while the spectra show high-frequency bands similar to those observed for planar meso-substituted porphyrins, there are several additional intense bands in the low-frequency region. Density functional calculations at the B3-LYP/6-31G(d) level were carried out for all four isotopomers, and calculated frequencies were scaled using a single factor of 0.98. The single factor scaling approach was validated on free base porphine where the RMS error was found to be 14.9 cm(-1). All the assigned bands in the high-frequency (> 1000 cm(-1)) region of TtBP were found to be due to vibrations similar in character to the in-plane skeletal modes of conventional planar porphyrins. In the low-frequency region, two of the bands, assigned as nu(8) (ca. 330 cm(-1)) and nu(16) (ca. 540 cm(-1)), are also found in planar porphyrins such as tetra-phenyl porphine (TPP) and tetra-iso-propyl porphine (IPP). Of the remaining three very strong bands, the lowest frequency band was assigned as gamma(12) (pyr swivel, obsd 415 cm(-1), calcd 407 cm(-1) in do). The next band, observed at 589 cm-1 in the do compound (calcd 583 cm(-1)), was assigned as a mode whose composition is a mixture of modes that were previously labeled gamma(13) (gamma(CmCaHmCa)) andy gamma(11) (pyr fold(asym)) in NiOEP. The final strong band, observed at 744 cm(-1) (calcd 746 cm(-1)), was assigned to a mode whose composition is again a mixture of gamma(11) and gamma(13), although here it is gamma(11) rather than gamma(13) which predominates. These bands have characters and positions similar to those of three of the four porphyrin ring-based, weak bands that have previously been observed for NiTPP. In addition there are several weaker bands in the TtBP spectra that are also

Interaction of directional, neuromuscular and egocentric constraints on the stability of preferred bimanual coordination patterns

We investigated how the relative direction of limb movements in external space (iso- and non-isodirectionality), muscular constraints (the relative timing of homologous muscle activation) and the egocentric frame of reference (moving simultaneously toward/away the longitudinal axis of the body) contribute to the stability of coordinated movements. In the first experiment, we attempted to determine the respective stability of isodirectional and non-isodirectional movements in between-persons coordination. In a second experiment, we determined the effect of the relative direction in external space, and of muscular constraints, on pattern stability during a within-person bimanual coordination task. In the third experiment we dissociated the effects on pattern stability of the muscular constraints, relative direction and egocentric frame of reference. The results showed that (1) simultaneous activation of homologous muscles resulted in more stable performance than simultaneous activation of non-homologous muscles during within-subject coordination, and that (2) isodirectional movements were more stable than non-isodirectional movements during between-persons coordination, confirming the role of the relative direction of the moving limbs in the stability of bimanual coordination. Moreover, the egocentric constraint was to some extent found distinguishable from the effect of the relative direction of the moving limbs in external space, and from the effect of the relative timing of muscle activation. In summary, the present study showed that relative direction of the moving limbs in external space and muscular constraints may interact either to stabilize or destabilize coordination patterns. (C) 2003 Published by Elsevier B.V.

Real time monitoring of the polymerisation of PMMA bone cement using Raman spectroscopy

In this investigation Raman spectroscopy was shown to be a method that could be used to monitor the polymerisation of PMMA bone cement. Presently there is no objective method that orthopaedic surgeons can use to quantify the curing process of cement during surgery. Raman spectroscopy is a non-invasive, non-destructive technique that could offer such an option. Two commercially available bone cements (Palacos® R and SmartSet® HV) and different storage conditions (4 and 22°C) were used to validate the technique. Raman spectroscopy was found to be repeatable across all conditions with the completion of the polymerisation process particularly easy to establish. All tests were benchmarked against current temperature monitoring methods outlined in ISO and ASTM standards. There was found to be close agreement with the standard methods and the Raman spectroscopy used in this study.

SRIF receptor subtype expression and involvement in positive and negative contractile effects of somatostatin-14 (SRIF-14) in ventricular cardiomyocytes.

Background/Aims: Somatostatin-14 (SRIF-14), a neuropeptide co-stored with acetylcholine in the cardiac parasympathetic innervation, exerts both positive and negative influences directly on contraction of ventricular cardiomyocytes, indicative of involvement of more than one of five known SRIF (SSTR) receptor subtypes. The aim was to characterize receptor subtype expression in adult rat ventricular cardiomyocytes and to investigate the influence of a series of SRIF (SSTR) subtype-selective agonists on contractile parameters. Methods: mRNA and protein expression of each receptor subtype were quantified by RT-PCR and immunoblotting respectively; for contraction studies, cells were stimulated at 0.5 Hz under basal conditions and in the presence of isoprenaline (ISO, 10-8M). Results: all five SRIF (SSTR) receptor subtypes were expressed in cardiomyocytes although SRIF1A (SSTR2) and SRIF2A (SSTR1) were less abundant than the other subtypes. L803087 (10-8M), a SRIF2B (SSTR4) agonist, attenuated ISO-stimulated peak contractile amplitude and prolonged relaxation time (T50). L796778 (10-7M), a SRIF1C (SSTR3) agonist, augmented basal and ISO-stimulated peak contractile amplitude; L779976 (10-8M) and L817818 (10-9M), agonists at SRIF1A (SSTR2) and SRIF1B (SSTR5) receptors, respectively, also augmented ISO-stimulated peak amplitude. Conclusion: these data support involvement of SRIF2B (SSTR4) receptors in the negative contractile effects of SRIF-14, while one or more of the three SRIF1 receptor subtypes (SSTR2, 3 or 5) may contribute to the positive contractile effects of SRIF-14.

Steady-State and Transient Performance of Biodiesel-Fueled Compression-Ignition-Based Electrical Generation

This paper investigates the performance characteristics of rapeseed methyl ester, EN 14214 biodiesel, when used for electrical generation in compression ignition engines. The work was inspired by the need to replace fossil diesel fuel with a sustainable low carbon alternative while maintaining generator performance, power quality, and compliance with ISO 8528-5. A 50-kVA Perkins diesel engine generator was used to assess the impact of biodiesel with particular regard to gen-set fuel consumption, load acceptance, and associated standards. Tests were performed on the diesel gen-set for islanded and grid-connected modes of operation, hence both steady-state and transient performance were fully explored. Performance comparisons were made with conventional fossil diesel fuel, revealing minimal technical barriers for electrical generation from this sustainable, carbon benign fuel. Recommendations for improved transient performance are proposed and validated through tests.

A new approach to peptide synthesis

A new approach to the synthesis of dipeptides is described based on the formation of the CONH-CHRCO bond by carbenoid N-H insertion, rather than the formation of the peptide bond itself. The key N-H insertion reaction was carried out by treating a mixt. of N-protected amino acid amide and tri-Et diazophosphonoacetate, EtO2CC(:N2)PO(OEt)2, with a catalytic amt. of Rh2(OAc)4 in toluene to form phosphonates, e.g. I (R1 = H, Me, iso-Pr, iso-Bu; R2 = PhCH2O2C, Me3CO2C) in good yield. Dehydro dipeptides, e.g. II (R1, R2 = same as above; R3 = Ph, iso-Pr, N-Boc-indol-3-yl) were prepd. by Wadsworth-Emmons reaction of the phosphonates I with R3CHO using DBU as base.

Effect of MWCNT addition on the thermal and rheological properties of polymethyl methacrylate bone cement

Multi-walled carbon nanotube (MWCNT)/polymethyl methacrylate (PMMA) composites with loadings ranging from 0.1 to 1.0 wt.% were prepared for use as bone cement. Unfunctionalised, carboxyl and amine functionalised MWCNT were used. Thermal properties were characterised in accordance with the International Standard for acrylic cements, ISO 5833:2002. The rate of reaction exotherm generated and thermal necrosis index (TNI) values were calculated. Polymerisation kinetics were characterised using parallel plate rheology and the exotherm during polymerisation was reduced by ˜4–34%, as a consequence of the MWCNT thermal conductivity. The rate of reaction was significantly altered, such that the setting times of the cements were extended (˜3–24%). Consequently, significant decreases in TNI values (ranging from 3% to 99%) were recorded, which could reduce the exothermic temperatures experienced in vivo and therefore prevent the likelihood of polymerising PMMA cement causing thermally-induced bone tissue necrosis. Thermal data was supported by the rheological characterisation results. Onset of polymerisation for PMMA cement exhibited a strong linear increase as a function of MWCNT loading, however, polymer gelation was not affected to the same degree. It is proposed that the chemically functionalised MWCNT altered PMMA bone cement polymerisation kinetics, reducing the rate of polymerisation, and hence, the reaction exotherm.

A search for interstellar gas-phase CO2 gas: Solid state abundance ratios

We present searches for gas-phase CO2 features in the ISO-SWS infrared spectra of four deeply embedded massive young stars, which all show strong solid CO2 absorption. The abundance of gas-phase CO2 is at most 2. 10(-7) with respect to H-2, and is less than 5% of that in the solid phase. This is in strong contrast to CO, which is a factor of 10-100 more abundant in the gas than in solid form in these objects. The gas/solid state ratios of CO2, CO and H2O are discussed in terms of the physical and chemical state of the clouds.

Optical and infrared spectroscopy of the type IInSN1998S: days 3-127

We present contemporary optical and infrared spectroscopic observations of the type IIn SN 1998S covering the period between 3 and 127 days after discovery. During the first week the spectra are characterized by prominent broad H, He and C III/N III emission lines with narrow peaks, superimposed on a very blue continuum (T similar to 24 000 K). In the following two weeks the C III/N III emission vanished, together with the broad emission components of the H and He lines. Broad, blueshifted absorption components appeared in the spectra. The temperature of the continuum also dropped to similar to 14000 K. By the end of the first month the spectrum comprised broad, blueshifted absorptions in H, He, Si II, Fe II and Sc II. By day 44, broad emission components in H and He reappeared in the spectra. These persisted to as late as days similar to 100-130, becoming increasingly asymmetric. We agree with Leonard et al. that the broad emission lines indicate interaction between the ejecta and circumstellar material (CSM) emitted by the progenitor. We also agree that the progenitor of SN 1998S appears to have gone through at least two phases of mass-loss, giving rise to two CSM zones. Examination of the spectra indicates that the inner zone extended to less than or equal to 90 au, while the outer CSM extended from 185 an to over 1800 au.

Delineation of a quick clay zone at Smørgrav, Norway, with electromagnetic methods under geotechnical constraints

In many coastal areas of North America and Scandinavia, post-glacial clay sediments have emerged above sea level due to iso-static uplift. These clays are often destabilised by fresh water leaching and transformed to so-called quick clays as at the investigated area at Smørgrav, Norway. Slight mechanical disturbances of these materials may trigger landslides. Since the leaching increases the electrical resistivity of quick clay as compared to normal marine clay, the application of electromagnetic (EM) methods is of particular interest in the study of quick clay structures.

For the first time, single and joint inversions of direct-current resistivity (DCR), radiomagnetotelluric (RMT) and controlled-source audiomagnetotelluric (CSAMT) data were applied to delineate a zone of quick clay. The resulting 2-D models of electrical resistivity correlate excellently with previously published data from a ground conductivity metre and resistivity logs from two resistivity cone penetration tests (RCPT) into marine clay and quick clay. The RCPT log into the central part of the quick clay identifies the electrical resistivity of the quick clay structure to lie between 10 and 80 O m. In combination with the 2-D inversion models, it becomes possible to delineate the vertical and horizontal extent of the quick clay zone. As compared to the inversions of single data sets, the joint inversion model exhibits sharper resistivity contrasts and its resistivity values are more characteristic of the expected geology. In our preferred joint inversion model, there is a clear demarcation between dry soil, marine clay, quick clay and bedrock, which consists of alum shale and limestone.

The effect of multiple micronutrient supplementation on left ventricular ejection fraction in patients with chronic stable heart failure: a randomized, placebo-controlled trial:A randomized, placebo-controlled trial

Objectives: This study sought to investigate the effect of a multiple micronutrient supplement on left ventricular ejection fraction (LVEF) in patients with heart failure. Background: Observational studies suggest that patients with heart failure have reduced intake and lower concentrations of a number of micronutrients. However, there have been very few intervention studies investigating the effect of micronutrient supplementation in patients with heart failure. Methods: This was a randomized, double-blind, placebo-controlled, parallel-group study involving 74 patients with chronic stable heart failure that compared multiple micronutrient supplementation taken once daily versus placebo for 12 months. The primary endpoint was LVEF assessed by cardiovascular magnetic resonance imaging or 3-dimensional echocardiography. Secondary endpoints were Minnesota Living With Heart Failure Questionnaire score, 6-min walk test distance, blood concentrations of N-terminal prohormone of brain natriuretic peptide, C-reactive protein, tumor necrosis factor alpha, interleukin-6, interleukin-10, and urinary levels of 8-iso-prostaglandin F2 alpha. Results: Blood concentrations of a number of micronutrients increased significantly in the micronutrient supplement group, indicating excellent compliance with the intervention. There was no significant difference in mean LVEF at 12 months between treatment groups after adjusting for baseline (mean difference: 1.6%, 95% confidence interval: -2.6 to 5.8, p = 0.441). There was also no significant difference in any of the secondary endpoints at 12 months between treatment groups. Conclusions: This study provides no evidence to support the routine treatment of patients with chronic stable heart failure with a multiple micronutrient supplement. (Micronutrient Supplementation in Patients With Heart Failure [MINT-HF]; NCT01005303).

Bead array for Listeria monocytogenes detection using specific monoclonal antibodies

To develop a detection method for human pathogenic Listeria monocytogenes, novel specific antibodies were obtained from hybridoma libraries generated by using formalin-killed and heat-killed L. monocytogenes as immunogens. Several monoclonal antibodies found to be specific to Listeria spp or L. monocytogenes were evaluated for their applicability as binders for bead array and sandwichELISA for detection of L. monocytogenes in buffer and in 11 different food types. The bead array format consistently demonstrated lower detection limits and was less affected by interference from food matrices than the sandwich ELISA format. However, the obtained detection limits were not sufficient to satisfy the required standard for L. monocytogenes testing. Therefore, the international organizationfor standardization (ISO 11290-1:1996) methods for pre-enrichment and enrichment were employed to increase the bacteria numbers. When compared to the standard plating method, the bead array was able to detect the bacteria with the same accuracy even at the 1 CFU level after only 24 hours of the enrichment period. In addition, Listeria-specific 3C3 and L. monocytogenes-specific 7G4 antibodies were successfully employed to construct a multiplex detection for Listeria, Salmonella and Campylobacter in a bead array format by combining with commercial Salmonella-specific and available Campylobacter-specific antibodies.

Voltage scalable high-speed robust hybrid arithmetic units using adaptive clocking

In this paper, we explore various arithmetic units for possible use in high-speed, high-yield ALUs operated at scaled supply voltage with adaptive clock stretching. We demonstrate that careful logic optimization of the existing arithmetic units (to create hybrid units) indeed make them further amenable to supply voltage scaling. Such hybrid units result from mixing right amount of fast arithmetic into the slower ones. Simulations on different hybrid adder and multipliers in BPTM 70 nm technology show 18%-50% improvements in power compared to standard adders with only 2%-8% increase in die-area at iso-yield. These optimized datapath units can be used to construct voltage scalable robust ALUs that can operate at high clock frequency with minimal performance degradation due to occasional clock stretching. © 2009 IEEE.

Low-Power Process-Variation Tolerant Arithmetic Units Using Input-Based Elastic Clocking

In this paper we propose a design methodology for low-power high-performance, process-variation tolerant architecture for arithmetic units. The novelty of our approach lies in the fact that possible delay failures due to process variations and/or voltage scaling are predicted in advance and addressed by employing an elastic clocking technique. The prediction mechanism exploits the dependence of delay of arithmetic units upon input data patterns and identifies specific inputs that activate the critical path. Under iso-yield conditions, the proposed design operates at a lower scaled down Vdd without any performance degradation, while it ensures a superlative yield under a design style employing nominal supply and transistor threshold voltage. Simulation results show power savings of upto 29%, energy per computation savings of upto 25.5% and yield enhancement of upto 11.1% compared to the conventional adders and multipliers implemented in the 70nm BPTM technology. We incorporated the proposed modules in the execution unit of a five stage DLX pipeline to measure performance using SPEC2000 benchmarks [9]. Maximum area and throughput penalty obtained were 10% and 3% respectively.

Critical evaluation of pulse-echo ultrasonic test method for the determination of setting and mechanical properties of acrylic bone cement: Influence of mixing technique

Currently there is no reliable objective method to quantify the setting properties of acrylic bone cements within an operating theatre environment. Ultrasonic technology can be used to determine the acoustic properties of the polymerising bone cement, which are linked to material properties and provide indications of the physical and chemical changes occurring within the cement. The focus of this study was the critical evaluation of pulse-echo ultrasonic test method in determining the setting and mechanical properties of three different acrylic bone cement when prepared under atmospheric and vacuum mixing conditions. Results indicated that the ultrasonic pulse-echo technique provided a highly reproducible and accurate method of monitoring the polymerisation reaction and indicating the principal setting parameters when compared to ISO 5833 standard, irrespective of the acrylic bone cement or mixing method used. However, applying the same test method to predict the final mechanical properties of acrylic bone cement did not prove a wholly accurate approach. Inhomogeneities within the cement microstructure and specimen geometry were found to have a significant influence on mechanical property predictions. Consideration of all the results suggests that the non-invasive and non-destructive pulse-echo ultrasonic test method is an effective and reliable method for following the full polymerisation reaction of acrylic bone cement in real-time and then determining the setting properties within a surgical theatre environment. However the application of similar technology for predicting the final mechanical properties of acrylic bone cement on a consistent basis may prove difficult.