Kinetics and mechanism of a fast leuco-Methylene Blue oxidation by copper(II)-halide species in acidic aqueous media

The kinetics of a fast leuco-Methylene Blue (LMB) re-oxidation to Methylene Blue (MB) by copper(II)-halide (Cl-, Br-) complexes in acidic aqueous media has been studied spectrophotometrically using a stopped-flow technique. The reaction follows a simple first order rate expression under an excess of the copper(II) species (and H+(aq)), and the pseudo-first order rate constant (k'(obs)) is largely independent of the atmosphere used (air, oxygen, argon). The rate law, at constant Cl- (Br-) anion concentration, is given by the expression: (d[MB+])/dt = ((k(a)K[H+] + k(b))/(1 + K[H+])).[Cu-II][LMB] = k'(obs)[LMB], where K is the protonation constant, and k(a) and k(b) are the pseudo-second order rate constants for protonated and deprotonated forms of LMB, respectively The rate law was determined based on the observed k'(obs) vs. [Cu-II] and [H+] dependences. The rate dramatically increases with [Cl-] over the range: 0.1-1.5 M, reflecting the following reactivity order: Cu2+(aq)

A Low Complexity Real-time MIMO-Preprocessing For Fixed Complexity Sphere Decoder

Modern Multiple-Input Multiple-Output (MIMO) communication systems place huge demands on embedded processing resources in terms of throughput, latency and resource utilization. State-of-the-art MIMO detector algorithms, such as Fixed-Complexity Sphere Decoding (FSD), rely on efficient channel preprocessing involving numerous calculations of the pseudo-inverse of the channel matrix by QR Decomposition (QRD) and ordering. These highly complicated operations can quickly become the critical prerequisite for real-time MIMO detection, exaggerated as the number of antennas in a MIMO detector increases. This paper describes a sorted QR decomposition (SQRD) algorithm extended for FSD, which significantly reduces the complexity and latency
of this preprocessing step and increases the throughput of MIMO detection. It merges the calculations of the QRD and ordering operations to avoid multiple iterations of QRD. Specifically, it shows that SQRD reduces the computational complexity by over 60-70% when compared to conventional
MIMO preprocessing algorithms. In 4x4 to 7x7 MIMO cases, the approach suffers merely 0.16-0.2 dB reduction in Bit Error Rate (BER) performance.

Kinetic and thermodynamics of chromium ions adsorption onto low-cost dolomite adsorbent

The chromium bearing wastewater in this study was used to simulate the low concentration discharge from a major aerospace manufacturing facility in the UK. Removal of chromium ions from aqueous solutions using raw dolomite was achieved using batch adsorption experiments. The effect of; initial Cr(VI) concentration, amount of adsorbent, solution temperature, dolomite particle size and shaking speed was studied. Maximum chromium removal was found at pH 2.0. A kinetic study yielded an optimum equilibrium time of 96 h with an adsorbent dose of 1 g/L Sorption studies were conducted over a concentration range of 5-50 mg/L Cr(VI) removal decreased with an increase in temperature (q(max): 20 degrees C = 10.01 mg/g; 30 degrees C = 8.385 mg/g; 40 degrees C = 6.654 mg/g; and 60 degrees C = 5.669 mg/g). Results suggest that the equilibrium adsorption was described by the Freundlich model. The kinetic processes of Cr(VI) adsorption onto dolomite were described in order to provide a more clear interpretation of the adsorption rate and uptake mechanism. The overall kinetic data was acceptably explained by a pseudo first-order rate model. Evaluated Delta G degrees and Delta H degrees specify the spontaneous and exothermic nature of the reaction. The adsorption takes place with a decrease in entropy (Delta S degrees is negative). (C) 2011 Elsevier B.V. All rights reserved.

Rates for repair of pBR 322 DNA radicals by thiols as measured by the gas explosion technique: evidence that counter-ion condensation and co-ion depletion are significant at physiological ionic strength.

Rates of rapair of pBR 322 plasmid DNA radicals by thiols of varying net charge (Z) at pH 7 and physiological ionic strength were measured using the oxygen explosion technique. The extent of conversion of supercoiled to relaxed circular plasmid was measured by HPLC as a function of the time of oxygen exposure before or after irradiation, the time-courses being fitted by a pseudo-first-order kinetic expression with k1 = k2[RSH]. Values of k2 (M-1 S-1) were: 2.1 x 10(5) (GSH, Z = -1), 1.4 x 10(6) (2-mercaptoethanol, Z = 0), 1.2 x 10(7) (cysteamine, Z = +1), 6.6 x 10(7) (WR-1065 or N-(2-mercaptoethyl)-1,3-diamino?? propane, Z = +2). The approximately 6-fold increase in rate with each unit increase in Z is attributed to concentration of cationic thiols near DNA as a consequence of counter-ion condensation and reduced levels of anionic thiols near DNA owing to co-ion depletion. The results are quantitatively consistent with chemical repair as a significant mechanism for radioprotection of cells by neutral and cationic thiols under aerobic conditions, but indicate that repair by GSH will compete effectively with oxygen only at low oxygen tension.

Nematode neuropeptide modulation of the vagina vera of Ascaris suum: in vitro effects of PF1, PF2, PF4, AF3 and AF4

Ascaris suum possesses a large number of FMRFamide-related peptides (FaRPs) of which KNEFIRFamide (AF1), KHEYLRFamide (AF2) and KSAYMRFamide (AF8/PF3) have been shown to modulate the intrinsic, rhythmic activity of the vagina vera of A. suum in vitro. In the present study, the effects of the nematode FaRPs, SDPNFLRFamide (PF1), SADPNFLREamide (PF2) and KPNFIRFamide (PF4) (from Panagrellus redivivus) and AVPGVLRFamide (AF3) and GDVPGVLRFamide (AF4) (from A. suum) on the in vitro activity of the vagina vera were examined. The effects of each of the peptides were qualitatively and quantitatively distinct. All 3 FaRPs from P. redivivus were inhibitory, causing a cessation of contractions. PF2 was 3 times more potent than PF1, with a threshold of 1 nM. Although PF4 was the least potent (threshold, 10 nM), its effects at greater than or equal to 10 nM were quantitatively the greatest. Both AF3 and AF4 (1 mu M) induced complex, multiphasic responses consisting of an initial contraction and spastic paralysis followed by a return of contractile activity of increased amplitude. AF3 was 3 times more potent than AF4. The effects of these peptides had some similarities to those observed on A. suum somatic body wall muscle in vitro, with PF1, PF2 and PF4 being inhibitory and AF3 and AF4 being excitatory.

Structural characterisation and pharmacology of KHEYLRFamide (AF2) and KSAYMRFamide (PF3/AF8) from Haemonchus contortus

The FMRFamide-related peptides (FaRPs), KHEYLRFamide (AF2) and KSAYMRFamide (PF3) were structurally characterised from the parasitic nematode of sheep, Haemonchus contortus (MH isolate). Both peptides were sequenced in a single gas-phase sequencing run and their structure confirmed by mass spectrometry which identified peptides of 920 Da (C-terminally amidated AF2) and 902/918 Da (C-terminally amidated non-oxidised/oxidised PF3, respectively). AF2 had inhibitory effects on H. contortus muscle and inhibited acetylcholine (ACh, 10 mu M)-induced contractions, with a threshold for activity of I mu M. PF3 induced concentration-dependent contractions of H. contortus (activity threshold, 10 nM) and enhanced ACh contractions. Compared with the MH isolate, an isolate of H. contortus which has reduced sensitivity to cholinergic drugs (Lawes isolate) was less sensitive to the effects of PF3. The concentration-response curves for the cholinergic compounds ACh and levamisole (LEV), and PF3, but not a control, KPNFIRFamide (PF4), showed a statistically similar shift. This study implicates PF3 in the modulation of cholinergic function in H. contortus. (C) 1999 Elsevier Science B.V. All rights reserved.

Modulation of the motility of the vagina vera of Ascaris suum in vitro by FMRFamide-related peptides

Ascaris suum contains a large number of FMRFamide-related peptides (FaRPs) of which KNEFIRFamide (AF1), KHEYLRFamide (AF2) and KSAYMRFamide (AF8, also called PF3) have been extensively studied and are known to exert actions on somatic muscle strips of the worm. In the present study, the effects of AF1, AF2 and AF8 on the activity of the vagina vera of female A. suum have been examined in vitro. The vagina vera is a muscular tube connecting the uterus and vagina uteri to the gonopore and is probably involved in regulating egg output. The tissue exhibited spontaneous, rhythmic contractions in vitro, which were modulated by each of the FaRPs tested. The effects of each of the peptides were qualitatively and quantitatively different, and in each case were reversible. AF1 (1 mu M) caused a biphasic response in the form of a transient lengthening of the preparation, followed by a shortening; contractions were initially inhibited but resumed 5 min post-addition of the peptide. Lower concentrations (less than or equal to 0.1 mu M) induced a less marked effect, with rhythmic contractions returning 5 min post-addition. AF2 and AF8 reduced contraction frequency at concentrations greater than or equal to 0.1 mu M. Both peptides also caused the tissue to shorten, although the effects of AF8 on baseline tension were inconsistent. The apparent potencies of AF1 and AF8 on contraction frequency of the vagina vera were 10-fold greater than AF2 and, unlike their actions on A. suum somatic body wall muscles, the actions of AF1 and AF2 were qualitatively different. Indeed, the effects of each of these FaRPs on the vagina vera were markedly different from those observed on the somatic muscle.

Pharmacological effects of nematode FMRFamide-related peptides (FaRPs) on muscle contractility of the trematode, Fasciola hepatica

The physiological effects of synthetic replicates of the nematode FaRPs, AF1 (KNEFIRFamide), AF2 (KHEYLRFamide), PF1 (SDPNFLRFamide), PF2 (SADPNFLRFamide), AF8/PF3 (KSAYMRFamide) and PF4 (KPNFIRFamide) were examined on muscle preparations of the liver fluke, Fasciola hepatica. Changes in contractility following the addition of the test compound were recorded using a photo-optic transducer system. Unlike the varied effects these peptides have on nematode somatic musculature, all were found to induce excitatory responses in the muscle activity of F. hepatica. While qualitative effects of the nematode peptides were similar in that they induced increases in both the amplitude and frequency of F. hepatica muscle contractions, they varied considerably in the potency of their excitatory effects. The threshold activity for each peptide was as follows: 10 mu M, PF1 and PF2; 3 mu M, AF1 and PF3; 1 mu M, AF2; and 30 nM, PF4. The results demonstrate, for the first time, the cross-phyla activity of nematode neuropeptides on the neuromuscular activity of a trematode.

Platyhelminth FMRFamide-related peptides

Platyhelminths are the most primitive metazoan phylum to possess a true central nervous system, comprising a brain and longitudinal nerve cords connected by commissures. Additional to the presence of classical neurotransmitters, the nervous systems of all major groups of flatworms examined have widespread and abundant peptidergic components, Decades of research on the major invertebrate phyla, Mollusca and Arthropoda, have revealed the primary structures and putative functions of several families of structurally related peptides, the best studied being the FMRFamide-related peptides (FaRPs). Recently, the first platyhelminth FaRP was isolated from the tapeworm, Moniezia expansa, and was found to be a hexapeptide amide, GNFFRFamide. Two additional PaRPs were isolated from species of turbellarians; these were pentapeptides, RYIRFamide (Artioposthia triangulata) and GYIRFamide (Dugesia tigrina). The primary structure of a monogenean or digenean FaRP has yet to be deduced. Preliminary physiological studies have shown that both of the turbellarian FaRPs elicit dose-dependent contractions of isolated digenean and turbellarian somatic muscle fibres. Unlike the high structural diversity of FaRPs found in molluscs, arthropods and nematodes, the complement of FaRPs in individual species of platyhelminths appears to be restricted to 1 or 2 related molecules. Much remains to be learnt about platyhelminth PaRPs, particularly from peptide isolation, molecular cloning of precursor proteins, receptor localization, and physiological studies. Copyright (C) 1996 Australian Society for Parasitology.

PLATYHELMINTH FMRFAMIDE-RELATED PEPTIDES (FARPS) CONTRACT SCHISTOSOMA-MANSONI (TREMATODA, DIGENEA) MUSCLE-FIBERS IN-VITRO

Molluscan FMRFamide and two recently discovered platyhelminth FMRFamide-related peptides (FaRPs), GNFFRFamide from the cestode Moniezia expansa and RYIRFamide from the terrestrial turbellarian Artioposthia triangulata, cause dose-dependent contractions of individual muscle fibres from Schistosoma mansoni in vitro. The most potent FaRP tested was the turbellarian peptide RYIRFamide, which produced a concentration-dependent effect between 10(-9) and 10(-7) M. FMRFamide and GNFFRFamide were less potent, inducing contractions between 10(-8)-10(-6) M and 10(-7)-10(-5) M respectively. The contractile effect of each of these peptides was blocked by the presence of 1 mu M FMR-D-Famide. FMRF free acid did not elicit contraction of the muscle fibres. The FaRP-induced contractions did not occur if the Ca2+ was omitted and 0.5 mu M EGTA. was added to the extracellular medium. The FaRP-induced contractions were not blocked by the Ca2+ channel blockers nicardipine, verapamil or diltiazem, although high Kf-induced contractions of these fibres were blocked by nicardipine. These data indicate the presence of FaRP receptors on schistosome muscle fibres and demonstrate their ability to mediate muscle contraction. The action of these endogenous flatworm peptides on schistosome muscle is the first demonstration of a direct excitatory effect of any putative neurotransmitter on the muscle of a flatworm, and establishes a role for FaRPs in neuromuscular transmission in trematodes. In addition, it provides the first evidence that the peptidergic nervous system is a rational target for chemotherapeutic attack in parasitic platyhelmiths.

Nonlinear electrostatic excitations of charged dust in degenerate ultra-dense quantum dusty plasmas

The linear and nonlinear properties of low-frequency electrostatic excitations of charged dust particles (or defects) in a dense collisionless, unmagnetized Thomas-Fermi plasma are investigated. A fully ionized three-component model plasma consisting of electrons, ions, and negatively charged massive dust grains is considered. Electrons and ions are assumed to be in a degenerate quantum state, obeying the Thomas-Fermi density distribution, whereas the inertial dust component is described by a set of classical fluid equations. Considering large-amplitude stationary profile travelling-waves in a moving reference frame, the fluid evolution equations are reduced to a pseudo-energy-balance equation, involving a Sagdeev-type potential function. The analysis describes the dynamics of supersonic dust-acoustic solitary waves in Thomas-Fermi plasmas, and provides exact predictions for their dynamical characteristics, whose dependence on relevant parameters (namely, the ion-to-electron Fermi temperature ratio, and the dust concentration) is investigated. An alternative route is also adopted, by assuming weakly varying small-amplitude disturbances off equilibrium, and then adopting a multiscale perturbation technique to derive a Korteweg–de Vries equation for the electrostatic potential, and finally solving in terms for electric potential pulses (electrostatic solitons). A critical comparison between the two methods reveals that they agree exactly in the small-amplitude, weakly superacoustic limit. The dust concentration (Havnes) parameter h = Zd0nd0/ne0 affects the propagation characteristics by modifying the phase speed, as well as the electron/ion Fermi temperatures. Our results aim at elucidating the characteristics of electrostatic excitations in dust-contaminated dense plasmas, e.g., in metallic electronic devices, and also arguably in supernova environments, where charged dust defects may occur in the quantum plasma regime.

Coelum non animum muto? Milton's Neo-Latin Poetry and Catholic Italy

Milton’s Elegiarum Liber, the first half of his Poemata published in Poems of Mr John Milton Both English and Latin (1645), concludes with a series of eight Latin epigrams: five bitterly anti-Catholic pieces on the failed Gunpowder Plot of 1605, followed by three encomiastic poems hymning the praises of an Italian soprano, Leonora Baroni, singing in Catholic Rome. The disparity in terms of subject matter and tone is self-evident yet surprising in an epigrammatic series that runs sequentially. Whereas the gunpowder epigrams denigrate Rome, the Leonora epigrams present the city as a cultured hub of inclusivity, the welcome host of a Neapolitan soprano. In providing the setting for a human song that both enthrals its audience and attests to the presence of a divine power, Rome now epitomizes something other than brute idolatry, clerical habit or doctrine. And for the poet this facilitates an interrogation of theological (especially Catholic) doctrines. Coelum non animum muto, dum trans mare curro wrote the homeward-bound Milton in the autograph book of Camillo Cardoini at Geneva on 10 June 1639. But that this was an animus that could indeed acclimatize to religious and cultural difference is suggested by the Latin poems which Milton “patch [ed] up” in the course of his Italian journey. Central to that acclimatisation, as this chapter argues, is Milton’s quasi-Catholic self-fashioning. Thus Mansus offers a poetic autobiography of sorts, a self-inscribed vita coloured by intertextually kaleidoscopic links with two Catholic poets of Renaissance Italy and their patron; Ad Leonoram 1 both invokes and interrogates Catholic doctrine before a Catholic audience only to view the whole through the lens of a neo-Platonic hermeticism that may refreshingly transcend religious difference. Finally, Epitaphium Damonis, composed upon Milton’s return home, seems to highlight the potential interconnectedness of Protestant England and Catholic Italy, through the Anglo-Italian identity of its deceased subject, and through a pseudo-monasticism suggested by the poem’s possible engagement with the hagiography of a Catholic Saint. Perhaps continental travel and the physical encounter with the symbols, personages and institutions of the other have engendered in the Milton of the Italian journey a tolerance or, more accurately, the manipulation of a seeming tolerance to serve poetic and cultural ends.


First reviewer:
Haan: a fine piece by the senior neo-Latinist in Milton studies.

Second reviewer:
Chapter 7 is ... a high-spot of the collection. Its argument that in his Latin poetry Milton’s is a ‘quasi-Catholic self-fashioning’ stressing ‘the potential interconnectedness of Protestant England and Catholic Italy’ is striking and is advanced with learning, clarity and insight. Its sensitive exploration of the paradox of Milton’s coupling of humanistically complimentary and tolerant address to Roman Catholic friends with fiercely Protestant partisanship demonstrates that there is much greater complexity to his poetic persona than the self-construction and self-presentation of the later works would suggest. The essay is always adroit and sure-footed, often critically acute and illuminating (as, for example, in its discussion of the adjective and adverb mollis and molliter in Mansus, or in the identification in n. 99 of hitherto unnoticed Virgilian echoes). It has the added merits of being very well written, precise and apt in its citation of evidence, and absolutely central to the concerns of the volume.

Radiochromic film spectroscopy of laser-accelerated proton beams using the FLUKA code and dosimetry traceable to primary standards

A new approach to spectroscopy of laser induced proton beams using radiochromic film (RCF) is presented. This approach allows primary standards of absorbed dose-to-water as used in radiotherapy to be transferred to the calibration of GafChromic HD-810 and EBT in a 29 MeV proton beam from the Birmingham cyclotron. These films were then irradiated in a common stack configuration using the TARANIS Nd:Glass multi-terawatt laser at Queens University Belfast, which can accelerate protons to 10-12 MeV, and a depth-dose curve was measured from a collimated beam. Previous work characterizing the relative effectiveness (RE) of GafChromic film as a function of energy was implemented into Monte Carlo depth-dose curves using FLUKA. A Bragg peak (BP) "library" for proton energies 0-15 MeV was generated, both with and without the RE function. These depth-response curves were iteratively summed in a FORTRAN routine to solve for the measured RCF depth-dose using a simple direct search algorithm. By comparing resultant spectra with both BP libraries, it was found that the effect of including the RE function accounted for an increase in the total number of protons by about 50%. To account for the energy loss due to a 20 mu m aluminum filter in front of the film stack, FLUKA was used to create a matrix containing the energy loss transformations for each individual energy bin. Multiplication by the pseudo-inverse of this matrix resulted in "up-shifting" protons to higher energies. Applying this correction to two laser shots gave further increases in the total number of protons, N of 31% and 56%. Failure to consider the relative response of RCF to lower proton energies and neglecting energy losses in a stack filter foil can potentially lead to significant underestimates of the total number of protons in RCF spectroscopy of the low energy protons produced by laser ablation of thin targets.

Role of basal extracellular Ca2+ entry during 5-HT-induced vasoconstriction of canine pulmonary arteries.

1. Measurements of artery contraction, cytosolic [Ca(2+)], and Ca(2+) permeability were made to examine contractile and cytosolic [Ca(2+)] responses of canine pulmonary arteries and isolated cells to 5-hydroxytryptamine (5-HT), and to determine the roles of intracellular Ca(2+) release and extracellular Ca(2+) entry in 5-HT responses. 2. The EC(50) for 5-HT-mediated contractions and cytosolic [Ca(2+)] increases was approximately 10(-7) M and responses were inhibited by ketanserin, a 5-HT(2A)-receptor antagonist. 3. 5-HT induced cytosolic [Ca(2+)] increases were blocked by 20 microM Xestospongin-C and by 2-APB (IC(50)=32 microM inhibitors of InsP(3) receptor activation. 4. 5-HT-mediated contractions were reliant on release of InsP(3) but not ryanodine-sensitive Ca(2+) stores. 5. 5-HT-mediated contractions and cytosolic [Ca(2+)] increases were partially inhibited by 10 microM nisoldipine, a voltage-dependent Ca(2+) channel blocker. 6. Extracellular Ca(2+) removal reduced 5-HT-mediated contractions further than nisoldipine and ablated cytosolic [Ca(2+)] increases and [Ca(2+)] oscillations. Similar to Ca(2+) removal, Ni(2+) reduced cytosolic [Ca(2+)] and [Ca(2+)] oscillations. 7. Mn(2+) quench of fura-2 and voltage-clamp experiments showed that 5-HT failed to activate any significant voltage-independent Ca(2+) entry pathways, including store-operated and receptor-activated nonselective cation channels. Ni(2+) but not nisoldipine or Gd(3+) blocked basal Mn(2+) entry. 8. Voltage-clamp experiments showed that simultaneous depletion of both InsP(3) and ryanodine-sensitive intracellular Ca(2+) stores activates a current with linear voltage dependence and a reversal potential consistent with it being a nonselective cation channel. 5-HT did not activate this current. 9. Basal Ca(2+) entry, rather than CCE, is important to maintain 5-HT-induced cytosolic [Ca(2+)] responses and contraction in canine pulmonary artery.

Phenol degradation by powdered metal ion modified titanium dioxide photocatalysts

Conventional water purification and disinfection generally involve potentially hazardous substances, some of which known to be carcinogenic in nature. Titanium dioxide photocatalytic processes provide an effective route to destroy hazardous organic contaminants. This present work explores the possibility of the removal of organic pollutants (phenol) by the application of TiO2 based photocatalysts. The production of series of metal ions doped or undoped TiO2 were carried out via a sol–gel method and a wet impregnation method. Undoped TiO2 and Cu doped TiO2 showed considerable phenol degradation. The efficiency of photocatalytic reaction largely depends on the photocatalysts and the methods of preparation the photocatalysts. The doping of Fe, Mn, and humic acid at 1.0 M% via sol–gel methods were detrimental for phenol degradation. The inhibitory effect of initial phenol concentration on initial phenol degradation rate reveals that photocatalytic decomposition of phenol follows pseudo zero order reaction kinetics. A concentration of > 1 g/L TiO2 and Cu doped TiO2 is required for the effective degradation of 50 mg/L of phenol at neutral pH. The rise in OH- at a higher pH values provides more hydroxyl radicals which are beneficial of phenol degradation. However, the competition among phenoxide ion, Cl- and OH- for the limited number of reactive sites on TiO2 will be a negative influence in the generation of hydroxyl radical. The dependence of phenol degradation rate on the light intensity was observed, which also implies that direct sunlight can be a substitute for the UV lamps and that photocatalytic treatment of organic pollutants using this technique shows some promise.