Cluster ion beam profiling of organics by secondary ion mass spectrometry – does sodium affect the molecular ion intensity at interfaces?

The use of cluster ion beam sputtering for depth profiling organic materials is of growing technological importance and is a very active area of research. At the 44th IUVSTA Workshop on “Sputtering and Ion Emission by Cluster Ion Beams”, recent results were presented of a cluster ion beam depth profile of a thin organic molecular layer on a silicon wafer substrate. Those data showed that the intensity of molecular secondary ions is observed to increase at the interface and this was explained in terms of the higher stopping power in the substrate and a consequently higher sputtering yield and even higher secondary ion molecular sputtering yield. An alternative hypothesis was postulated in the workshop discussion which may be paraphrased as: “under primary ion bombardment of an organic layer, mobile ions such as sodium may migrate to the interface with the inorganic substrate and this enhancement of the sodium concentration increases the ionisation probability, so increasing the molecular ion yield observed at the interface”. It is important to understand if measurement artefacts occur at interfaces for quantification as these are of great technological relevance – for example, the concentration of drug in a drug delivery system. Here, we evaluate the above hypothesis using a sample that exhibits regions of high and low sodium concentration at both the organic surface and the interface with the silicon wafer substrate. There is no evidence to support the hypothesis that the probability of molecular secondary ion ionisation is related to the sodium concentration at these levels. © Crown copyright 2008. Reproduced with the permission of Her Majesty's Stationery Office. Published by John Wiley & Sons, Ltd.     

C60 ion sputtering of layered organic materials

Two different organic materials, Irganox1010 and Irganox3114, were vacuum deposited as alternating layers. The layers of Irganox3114 were thin (∼2.5 nm) in comparison to the Irganox1010 (∼55 or ∼90 nm); we call these ‘organic delta layers’. Both materials are shown to have identical sputtering yields and the alternating layers may be used to determine some of the important metrological parameters for cluster ion beam depth profiling of organic materials. The sputtering yield for C₆₀ ions is shown to diminish with ion dose. Comparison with atomic force microscopy data from films of pure Irganox1010, demonstrates that the depth resolution is limited by the development of topography. Secondary ion intensities are a well-behaved function of sputtering yield and may be employed to obtain useful analytical information. Organic delta layers are shown to be valuable reference materials for comparing the capabilities of different cluster ion sources and experimental arrangements for the depth profiling of organic materials.     

Patient Versus Partner Perception of Voice Handicap

The primary purpose of this study was to compare patient's and communication partner's perceptions of handicap secondary to dysphonia. A secondary purpose was to compare patient health-related quality of life (HRQOL) to that of speakers with normal voice. Participants were 20 adults (mean age=69.15 years) with dysphonia and their communication partners. Patients completed the Voice Handicap Index (VHI), a questionnaire of self-perceived voice handicap, and the Short-Form 36 (SF-36), a general health questionnaire. Partners completed the Voice Handicap Index-Partner (VHI-P), a questionnaire derived from the VHI for this pilot study, to gauge partner perception of voice handicap. Patients in this study viewed themselves as only moderately handicapped by their dysphonia and their partners were in close agreement. Patients and their partners were also in close agreement on each of three VHI subscales (physical, functional, and emotional), and in all cases the physical domain was perceived by both patients and their partners to be most handicapped. Patients had lower SF-36 mean scores than those of persons with normal voice from the general U.S. population on scales assessing physical functioning, physical role, general health, vitality, social functioning, emotional role, and mental health. The results of this study are consistent with previous studies examining patient-partner agreement, which consider proxy ratings to be a useful alternative or collaborative source of patient's self-perception. Further research regarding the reliability of patient and partner agreement is necessary to most effectively assess and manage patients with dysphonia.     

Analysis of thin films and molecular orientation using cluster SIMS

A study of phenylalanine films of different thicknesses from submonolayer to 55 nm on Si wafers has been made using Bi_n⁺ and C₆₀⁺ cluster primary ions in static SIMS. This shows that the effect of film thickness on ion yield is very similar for all primary ions, with an enhanced molecular yield at approximately 1 monolayer attributed to substrate backscattering. The static SIMS ion yields of phenylalanine at different thicknesses are, in principle, the equivalent of a static SIMS depth profile, without the complication of ion beam damage and roughness resulting from sputtering to the relevant thickness. Analyzing thin films of phenylalanine of different thicknesses allows an interpretation of molecular bonding to, and orientation on, the silicon substrate that is confirmed by XPS. The large crater size for cluster ions has interesting effects on the secondary ion intensities of both the overlayer and the substrate for monolayer and submonolayer quantities. This study expands the capability of SIMS for identification of the chemical structure of molecules at surfaces. © Crown copyright 2010.     

Formulation of Topical Dosage Forms Containing Synthetic and Natural Anti-Inflammatory Agents for the Treatment of Rheumatoid Arthritis

Topical anti-inflammatory and analgesic effect for the treatment of rheumatoid arthritis is of major interest because of their fewer side effects compared to oral therapy. The purpose of this study was to prepare different types of topical formulations (ointments and gels) containing synthetic and natural anti-inflammatory agents with different excipients (e.g.,: surfactants, gel-forming) for the treatment of rheumatoid arthritis. The combination of Non-Steroidal Anti-Inflammatory Drugs (NSAIDs), diclofenac sodium, a topical analgesic agent methyl salicylate, and a lyophilized extract of Calendula officinalis with antioxidant effect were used in our formulations. The aim was to select the appropriate excipients and dosage form for the formulation in order to enhance the diffusion of active substances and to certify the antioxidant, analgesic, and anti-inflammatory effects of these formulations. To characterize the physicochemical properties of the formulations, rheological studies, and texture profile analysis were carried out. Membrane diffusion and permeability studies were performed with Franz-diffusion method. The therapeutic properties of the formulations have been proven by an antioxidant assay and a randomized prospective study that was carried out on 115 patients with rheumatoid arthritis. The results showed that the treatment with the gel containing diclofenac sodium, methyl salicylate, and lyophilized Calendula officinalis as active ingredients, 2-propenoic acid homopolymer (Synthalen K) as gel-forming excipient, distilled water, triethanolamine, and glycerol had a beneficial analgesic and local anti-inflammatory effect.     

Mesoscopic nanoshells: geometry-dependent plasmon resonances beyond the quasistatic limit

The plasmon response of a spherical metallic shell becomes significantly more complex as its size is increased beyond the quasistatic limit. With increasing size and decreasing aspect ratio (r1/r2), higher order multipolar modes contribute in a more dominant manner, and two distinct core-shell geometries exist that provide the same dipole plasmon resonance, with differing relative multipolar contributions in their overall spectral response. With further increase in particle size, the geometric tunability of the core-shell structure disappears, and in the infinite radius limit the plasmon response is consistent with that of a thin metallic film.     

Fractionation of Cynara cardunculus (cardoon) biomass by dilute-acid pretreatment

Cynara cardunculus L. (cardoon) is a Mediterranean perennial herb offering good potential as substrate for sustainable production of bioethanol. In this work the first approach to the study of dilute-acid pretreatment of cardoon biomass for biological conversion was made. The influence of temperature (160-200 degrees C), acid concentration (0-0.2% [w/w]), and solid concentration (5-10% [w/v]) in the formation of free sugars and sugar decomposition products in the prehydrolyzate was studied using a response surface methodology. Results show a negative interaction effect between acid concentration and temperature in xylose recovery yield in prehydrolyzate, whereas dry matter concentration does not exert a significant effect. Xylose recovery yield reaches a maximum of about 80% of the content in dry untreated raw material at 180 degrees C and 0.1 or 0.2% acid addition. At these conditions the ratio of monomers found in prehydrolyzate in relation to total sugar yield for xylose is close to 100%. Furfural concentration, the major furan determined in the prehydrolyzate, increases as pretreatment severity rises. Maximum furfural yield of 4.2 g/100 g dry untreated raw material was found at 200 degrees C and 0.2% acid concentration. The yield of furfural at the conditions in which maximum xylose recovery is attained is substantially lower, less than 2 g/100 g dry untreated raw material. This fact supports the idea of using moderate temperatures in dilute-acid processes, which at the same time provides reasonably high sugar recovery yield and avoids high inhibitory products formation.     

Comparative X-ray structural study of laterally mono-ethyl substituted 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetra-methoxycalix[4]arene and its non-substituted parent compound including guest free and solvated forms. Chemical straightening of guest channels

Three solvate crystal structures of the laterally ethyl substituted tetra-tert-butyltetramethoxycalix[4]arene 1 [(1·THF (1a), 1·CHCl₃ (1b) and 1·CH₂Cl₂ (1c)] are compared to the corresponding solvent-free structure (1) using single crystal X-ray structure determination, isostructurality and molecular isometricity calculations. To study the effect of the lateral substitution, the laterally non-substituted host with the guest THF (2a) is also included to the comparison. The calixarene molecules in the different structures all adopt the partial cone conformation with different affection of the respective guest molecules, always being positioned interstitially. Depending on the lateral substitution and the size of the included guests, the molecular conformation of the calix[4]arene shows small differences relating to the alignment of the arene units. The channels disposable of the solvent guest molecules in the crystal structures straighten as the effect of lateral substitution of the host calix[4]arene. The orthorhombic crystal structures of 1a–c are isostructural irrespective of the included solvent molecules, while 1 and 2a crystallise in the same monoclinic space group.     

Unusual mixed solvent supramolecular crystal framework formed of a new tecton-like tetracarboxylic building block

A new tecton-like tetracarboxylic compound 1 featuring two isophthalic acid groups attached to both ends of a rigid 1,3-butadiyne spacer unit is synthesised using acetylene blocking/deblocking and coupling techniques. Crystallisation of 1 from DMSO-chloroform solution gives rise to the formation of an unusual mixed solvent crystalline framework structure 1a containing DMSO and chloroform as secondary and tertiary components in 1:2:1 stoichiometric ratio. The X-ray crystal structure of 1a shows interesting stacking mode and hydrogen-bonded, 3D network architecture with the two solvent species being involved in different behaviour pattern.