Recent development of intermediate ion/neutral complexes

The fundamental aspects of ion/neutral complex as an important intermediate of unimolecular fragmentation in mass spectrometry have been summarized in this review, especially for the classified description of its formations, characteristics, reactions, investigation methods, recent achievements and application. Meanwhile, another kind of proton-bound complex, which is a special type of ion/neutral complex, has been also introduced briefly. Among them, a part of authors' work was included.

Ion-molecule reactions of cis- and trans-cyclopropane derivatives with methane, acetone and vinyl acetate under chemical ionization conditions

Ion-molecule reactions of four isomeric cyclopropane derivatives were investigated under chemical ionization(CI) conditions, using methane, acetone and vinyl acetate as reagent gases, The methane positive-ion CI mass spectra of each of two isomer pairs 1,2 and 3,4 are identical, and so are the collision-induced dissociation (CTD) spectra of the protonated molecules of each of the two isomer pairs, The protonation reactions for the isomer pairs 1,2 and 3,4 occurred on the sites of the carboxyl groups and the R groups, respectively, Differences between isomers 1 and 2 are observed in their acetone (A) positive-ion CI mass spectra and in the CID spectra of their adduct ions ([M+H+A](+)), The adduct ions of compounds 2, 3 and 4 with protonated acetone and with protonated acetone dimer are observed in their CI mass spectra, However, only the adduct ions of compound 1 with protonated acetone appear in its CI mass spectrum, The protonated dimers of each of the four compounds are found in their vinyl acetate positive-ion CI mass spectra, and the CID spectra of these dimers for isomers 1 and 2 can also reflect their stereostructural difference. (C) 1998 John Wiley & Sons, Ltd.

Irradiation damage on BaLiF3 crystallites and its suppression by rare-earth ion doping

The x-ray and gamma-ray induced damage in BaLiF3 crystallites and its suppression by rare earth ion doping have been studied by electron spin resonance and thermally stimulated luminescence methods. It has been found that the x-ray irradiation damage is light and can be erased easily. This shows that the BaLiF3 crystallite is an ideal host for x-ray storage material. But the damage induced by gamma-ray has been found to be relatively hard to recover; however the gamma-ray irradiation hardness can be improved by rare earth (e.g., La3+, Yb3+) ion doping. So the BaLiF3 is also promising material for being used in detection of high-energy particles (e.g., gamma-ray).

Fragmentations of some bifunctional phenylether compounds by intermediate ion/neutral complexes

The fragmentations of three bifunctional phenylether compounds including 2-(2, 6-dichloro)phenoxyl propionitrile, N-hydroxyl-4-butoxyl phenylacetyl amine(bufexamc) and 2-(1-methylethoxyl) phenol methylcarbamate (Propoxur) under electron impact ionization were reported, Metastable ion(MI) and collision-induced dissociation(CID) at a low energy have been used to study the fragmentation pathways from molecular ions. Apart from the simple bond cleavages, and the unimolecular dissociations via ion/neutral complex intermediate as a competitive mechanism were demonstrated, Moreover, the intramolecular hydrogen transfer and double hydrogen transfers in the fragmentations of these compounds were discussed in detail.

LUMINESCENCE AND ENERGY-TRANSFER OF RARE-EARTH-METAL IONS IN MG2Y8(SIO4)(6)O-2

The photoluminescence of Ce3+, Tb3+ and Sm3+, and energy transfer from Ce3+ to Tb3+, Dy3+ and Sm3+ in Mg2Y8(SiOd(4))(6)O-2 are reported and discussed. The Ce3+ ion shows blue luminescence under UV excitation, and occupies simultaneously the 4f site and 6h site in the host lattice. The optimum concentrations for the D-5(3) and D-5(4) emissions of Tb3+ and the (4)G(5/2) emission of Sm3+ are determined to be 0.04, 0.20 and 0.10 mol in every mol of Mg2Y8(SiO4)(6)O-2, respectively. The critical distances responsible for the cross-relaxation between the D-5(3)-D-5(4) and F-7(6)-F-7(0) transitions of Tb3+ and between the (4)G(5/2)-F-4(9/2) and H-6(5/2)-F-4(9/2) transitions of Sm3+ are estimated to be 1.43 and 1.06 nm, respectively. Both Tb3+ and Dy3+ can be sensitized by Ce3+, but Ce3+ and Sm3+ quench each other.

LUMINESCENCE OF BI(3+) AND THE ENERGY-TRANSFER FROM BI(3+) TO R(3+) (R=EU,DY,SM,TB) IN ALKALINE-EARTH BORATES

At room temperature, the Bi3+ ion shows broad band characters of its luminescence in Ca2B2O5, M3B2O6 ( M=Ca,Sr ) and SrB4O7. The maxima of the Bi3+ S-1(0)-->P-3(1) absorption bands are located in the range of 240-300nm, but the energy variation of the corresponding P-3(1)-->S-1(0) emissions is very large. The maxima of these emission bands change from 350nm in Ca3B2O6;Bi3+ to 586nm in SrB4O7:Bi3+. The Stokes shift of the Bi3+ luminescence increases from 6118 cm-1, in Ca2B2O5:Bi3+, to 24439 cm-1, in SrB4O7:Bi3+. The emission intensity of the Bi3+ luminescence increases with the decreasing Stokes shift. It has been found that in Ca2B2O5, the Bi3+ ion could transfer its excitation energy to the R3+ ions ( R=Eu, Dy, Sm, Tb ) , but in, Ca3B2O6 and Sr3B2O6, only Bi3+-->Eu3+ was observed. No energy transfer from Bi3+ to R3+ was detected in SrB4O7.

Hydrogen ion reduction in the process of iron rusting

Since the acceptance of the electrochemical rusting mechanism, oxygen reduction has been considered the main cathodic process, while H+ reduction has been overlooked for the past four decades because oxygen can be readily renewed due to the thin layer Of Solution film formed during atmospheric corrosion. This study shows that measurable hydrogen call be detected at the surface opposite to the corroding side of the specimen during wet-dry cycles, and a clear correlation exists between the quantities of hydrogen permeated through iron sheet and weight loss. Results Suggest the intrinsic importance of H+ reduction that merits further investigation. (c) 2004 Elsevier Ltd. All rights reserved.

A velocity map ion-imaging study on ketene photodissociation at 208 and 213 nm: Rotational dependence of product angular anisotropy

Photodissociation dynamics of ketene following excitation at 208.59 and 213.24 nm have been investigated using the velocity map ion-imaging method. Both the angular distribution and translational energy distribution of the CO products at different rotational and vibrational states have been obtained. No significant difference in the translational energy distributions for different CO rotational state products has been observed at both excitation wavelengths. The anisotropy parameter beta is, however, noticeably different for different CO rotational state products at both excitation wavelengths. For lower rotational states of the CO product, beta is smaller than zero, while beta is larger than zero for CO at higher rotational states. The observed rotational dependence of angular anisotropy is interpreted as the dynamical influence of a peculiar conical intersection between the B-1(1) excited state and (1)A(2) state along the C-S-I coordinate.

Identification of phospholipid structures in human blood by direct-injection quadrupole-linear ion-trap mass spectrometry

Direct-injection electrospray ionization mass spectrometry in combination with information-dependent data acquisition (IDA), using a triple-quadrupole/linear ion trap combination, allows high-throughput qualitative analysis of complex phospholipid species from child whole blood. In the IDA experiments, scans to detect specific head groups (precursor ion or neutral loss scans) were used as survey scans to detect phospholipid classes. An enhanced resolution scan was then used to confirm the mass assignments, and the enhanced product ion scan was implemented as a dependent scan to determine the composition of each phospholipid class. These survey and dependent scans were performed sequentially and repeated for the entire duration of analysis, thus providing the maximum information from a single injection. In this way, 50 different phospholipids belonging to the phosphatidylethanolamine, phosphatidylserine, phosphatidylinositol, phosphatidylcholine and sphingomyelin classes were identified in child whole blood. Copyright (C) 2005 John Wiley & Sons, Ltd.

Optical and ion-scattering study of SiO2 layers thermally grown on 4H-SiC

Jenkins, Tudor; Hayton, D.J.; Bailey, P.; Noakes, T.C.Q., (2002) 'Optical and ion-scattering study of SiO2 layers thermally grown on 4H-SiC', Semiconductor Science and Technology 17 pp.L29-L32 RAE2008

Herbal supplements: Recent findings in exercise, health and weight loss

Natural herbs have been in use for weight loss purposes since history began. However, the current global obesity epidemic and the rise in obesity-related chronic diseases, including type-II diabetes and cancer, have highlighted the need for novel and effective approaches for herbal remedies. Whilst the popularity of several prescribed and non-prescribed slimming aids and herbal plant supplements have been marketed for their weight loss efficacy, single and multi-ingredient herbal supplements are still being investigated for their single or combined weight loss benefits. Limited research have highlighted an interesting efficacy for several popular herbal plant supplements including caffeine and capsaicin, Ayurvedic preparations and herbal teas, resulting in various degrees of effectiveness including thermogenic, appetite control and psychological benefits such as mood state. Recent research has suggested acute augmented weight-loss effects of combining herbal ingestion with exercise. For example, ingesting green tea, yerba mate and/or caffeine have been shown to increase metabolic rate, and augmented fatty acid metabolism and to increase energy expenditure from fatty acid sources during exercise with various intensities, particularly at low and moderate intensities. Other promising weight-loss effects have also been also reported for combining exercise with multi-ingredient herbal supplements, particularly those that are rich in phytochemicals and caffeoyl derivatives. Combining herbal ingestions with exercise still require further research in order to establish the supplementation most effective protocols in terms of dosage and timing, and to determine the long-term benefits, particularly those related to exercise protocols, and the long term adherence to sustain the weight loss outcomes.

An Energy-conscious Transport Protocol for Multi-hop Wireless Networks

We present a transport protocol whose goal is to reduce power consumption without compromising delivery requirements of applications. To meet its goal of energy efficiency, our transport protocol (1) contains mechanisms to balance end-to-end vs. local retransmissions; (2) minimizes acknowledgment traffic using receiver regulated rate-based flow control combined with selected acknowledgements and in-network caching of packets; and (3) aggressively seeks to avoid any congestion-based packet loss. Within a recently developed ultra low-power multi-hop wireless network system, extensive simulations and experimental results demonstrate that our transport protocol meets its goal of preserving the energy efficiency of the underlying network.

Energy storage systems for wave energy converters and microgrids

The thesis initially gives an overview of the wave industry and the current state of some of the leading technologies as well as the energy storage systems that are inherently part of the power take-off mechanism. The benefits of electrical energy storage systems for wave energy converters are then outlined as well as the key parameters required from them. The options for storage systems are investigated and the reasons for examining supercapacitors and lithium-ion batteries in more detail are shown. The thesis then focusses on a particular type of offshore wave energy converter in its analysis, the backward bent duct buoy employing a Wells turbine. Variable speed strategies from the research literature which make use of the energy stored in the turbine inertia are examined for this system, and based on this analysis an appropriate scheme is selected. A supercapacitor power smoothing approach is presented in conjunction with the variable speed strategy. As long component lifetime is a requirement for offshore wave energy converters, a computer-controlled test rig has been built to validate supercapacitor lifetimes to manufacturer’s specifications. The test rig is also utilised to determine the effect of temperature on supercapacitors, and determine application lifetime. Cycle testing is carried out on individual supercapacitors at room temperature, and also at rated temperature utilising a thermal chamber and equipment programmed through the general purpose interface bus by Matlab. Application testing is carried out using time-compressed scaled-power profiles from the model to allow a comparison of lifetime degradation. Further applications of supercapacitors in offshore wave energy converters are then explored. These include start-up of the non-self-starting Wells turbine, and low-voltage ride-through examined to the limits specified in the Irish grid code for wind turbines. These applications are investigated with a more complete model of the system that includes a detailed back-to-back converter coupling a permanent magnet synchronous generator to the grid. Supercapacitors have been utilised in combination with battery systems for many applications to aid with peak power requirements and have been shown to improve the performance of these energy storage systems. The design, implementation, and construction of coupling a 5 kW h lithium-ion battery to a microgrid are described. The high voltage battery employed a continuous power rating of 10 kW and was designed for the future EV market with a controller area network interface. This build gives a general insight to some of the engineering, planning, safety, and cost requirements of implementing a high power energy storage system near or on an offshore device for interface to a microgrid or grid.

Comparison of a reduced carbohydrate and reduced fat diet for LDL, HDL, and VLDL subclasses during 9-months of weight maintenance subsequent to weight loss.

OBJECTIVES: This study compared LDL, HDL, and VLDL subclasses in overweight or obese adults consuming either a reduced carbohydrate (RC) or reduced fat (RF) weight maintenance diet for 9 months following significant weight loss. METHODS: Thirty-five (21 RC; 14 RF) overweight or obese middle-aged adults completed a 1-year weight management clinic. Participants met weekly for the first six months and bi-weekly thereafter. Meetings included instruction for diet, physical activity, and behavior change related to weight management. Additionally, participants followed a liquid very low-energy diet of approximately 2092 kJ per day for the first three months of the study. Subsequently, participants followed a dietary plan for nine months that targeted a reduced percentage of carbohydrate (approximately 20%) or fat (approximately 30%) intake and an energy intake level calculated to maintain weight loss. Lipid subclasses using NMR spectroscopy were analyzed prior to weight loss and at multiple intervals during weight maintenance. RESULTS: Body weight change was not significantly different within or between groups during weight maintenance (p>0.05). The RC group showed significant increases in mean LDL size, large LDL, total HDL, large and small HDL, mean VLDL size, and large VLDL during weight maintenance while the RF group showed increases in total HDL, large and small HDL, total VLDL, and large, medium, and small VLDL (p<0.05). Group*time interactions were significant for large and medium VLDL (p>0.05). CONCLUSION: Some individual lipid subclasses improved in both dietary groups. Large and medium VLDL subclasses increased to a greater extent across weight maintenance in the RF group.

Atherosclerosis: Viewing the problem from a different perspective including possible treatment options

This paper proposes that atherosclerosis is initiated by a signaling event that deposits calcium hydroxyapatite (Ca-HAP). This event is preceded by a loss of mechanical structure in the arterial wall. After Ca-HAP has been deposited, it is unlikely that it will be reabsorbed because the solubility product constant (K sp) is very small, and the large stores of Ca +2 and PO 4-3 in the bones oppose any attempts to dissolve Ca-HAP by decreasing the common ions. The hydroxide ion (OH -) of Ca-HAP can be displaced in nature by fluoride (F -) and carbonate (CO 3-2) ions, and it is proposed that anions associated with cholesterol ester hydrolysis and, in very small quantities, the enolate of 7-ketocholesterol could also displace the OH -of Ca-HAP, forming an ionic bond. The free energy of hydration of Ca-HAP at 310 K is most likely negative, and the ionic radii of the anions associated with the hydrolysis of cholesterol ester are compatible with the substitution. Furthermore, examination of the pathology of atherosclerotic lesions by Raman and NMR spectroscopy and confocal microscopy supports deposition of Ca-HAP associated with cholesterol. Investigating the affinity of intermediates of cholesterol hydrolysis for Ca-HAP compared to lipoproteins such as HDL, LDL, and VLDL using isothermic titration calorimetry could add proof of this concept and may lead to the development of a new class of medications targeted at the deposition of cholesterol within Ca-HAP. Treatment of acute ischemic events as a consequence of atherosclerosis with denitrogenation and oxygenation is discussed. © the author(s), publisher and licensee Libertas Academica Ltd.