How nanoparticles encapsulating fluorophores allow a double detection of biomolecules by localized surface plasmon resonance and luminescence

The paper shows how polysiloxane particles encapsulating fluorophores can be successfully used to detect biotin-streptavidin binding by two types of technique. After functionalization of the particles by streptavidin, the fixation of the biomolecule can indeed be detected by a shift of the localized surface plasmon resonance of the biotinylated gold dots used as substrate and by the luminescence of the fluorophores evidenced by scanning near-field optical microscopy. The development of particles allowing such a double detection opens a route for increasing the reliability of biological detection and for multi-labelling strategies crossing both detection principles.

Prediction of the separation number of capillary columns in programmed temperature gas chromatographic analysis

The efficiency of capillary columns in programmed temperature analysis can be evaluated by calculation of the separation number ("Trennzahl"). A procedure for the prediction of this parameter at various initial temperatures, carrier gas pressures and heating rates, by using as the starting data the retention times and the peak widths obtained in some isobaric and isothermal runs is described. An equation is proposed that permits to obtain the values of the peak width at half height in any isothermal and linearly programmed temperature gas chromatographic run and therefore to calculate the separation number value. The effect on this parameter of the column polarity was investigated by using polar and non-polar compounds (n-alkanes and 1-alcohols).

Room-temperature continuous-wave operation of Ti:sapphire buried channel-waveguide lasers fabricated via proton implantation

Fabrication and laser operation of proton-implanted Ti:sapphire buried channel waveguides is reported for the first time to our knowledge. Without any postimplantation annealing of the structures, continuous laser operation near 780 nm was demonstrated at room temperature at an absorbed pump power threshold of 230 mW. Single-transverse-mode laser emission was observed with measured beam propagation factors M(2)(x) and M(2)(y) of 1.5 and 1.2, respectively. An output power of 12.4 mW for 1 W pump power was obtained with an output coupler of 4.6% transmission at the signal wavelength. Higher output powers were measured in waveguides with larger cross sections exhibiting multimode laser emission.

Factors affecting dropout in outpatient eating disorder treatment

OBJECTIVE

To evaluate the incidence and effects of factors potentially influencing eating disordered patients' dropping out of outpatient cognitive-behavioural therapy (CBT).

METHOD

Sixty-seven (64 female, 3 male) patients with eating disorders participated in the study. All patients followed a multidisciplinary team approach for a median period of 9 months. Several factors potentially affecting dropout were retrospectively assessed prior to treatment.

RESULTS

The dropout rate was significantly higher in patients with purging anorexia nervosa (AN) compared to those with restrictive AN, bulimia nervosa and eating disorder not otherwise specified (33% vs. 27%, 25% or 21%, respectively, p<0.05). Among several factors influencing dropout, there was a significant association of patient low cooperativeness, purging episodes, restrictive eating, use of several weight control practices and psychiatric co-morbidity in patients who dropped out compared to completers (all p<0.05).

CONCLUSIONS

In outpatient eating disorder treatment, non-compliance and premature interruption of therapy are affected primarily by factors which are related to patients' attitude and behaviour. These factors should be carefully addressed in patients with eating disorders to improve outcome.

Prediction of theoretical plate number in isothermal gas chromatographic analysis on capillary columns

A method for the prediction of the efficiency of gas chromatographic analysis in isothermal conditions by using experimental data of 1-alcohols and n-alkanes measured on capillary columns filled with polar and non-polar stationary phases in isothermal and isobaric conditions is described. The theoretical plate height trend indicates the change of separation efficiency as a function of inlet pressure and column temperature. By evaluating the variation of the diffusion coefficients of the analysed compounds into the mobile and stationary phase it is possible to predict the column efficiency and the number of theoretical plates at any temperature.

Cerebral folate deficiency with developmental delay, autism, and response to folinic acid

The authors describe a 6-year-old girl with developmental delay, psychomotor regression, seizures, mental retardation, and autistic features associated with low CSF levels of 5-methyltetrahydrofolate, the biologically active form of folates in CSF and blood. Folate and B12 levels were normal in peripheral tissues, suggesting cerebral folate deficiency. Treatment with folinic acid corrected CSF abnormalities and improved motor skills.

Classification and comparison of capillary columns by determination of the solution enthalpy of polar and non polar probes

The behaviour and separation characteristics of capillary columns containing different stationary phases (bonded methyl- and methylphenylsiloxanes and polyglycols, and carbon layer and porous polymer) were classified and compared by measuring the values of the solution enthalpy DeltaHs of n-alkanes and 1-alcohols at various temperatures. The difference in DeltaHs values between straight-chain 1-alcohols and n-alkanes with the same number of carbon atom (DeltaDeltaHs) does not change with changing temperature when gas-liquid partition stationary phases are used, but depends on the column composition and polarity and therefore permits to evaluate the influence of polarity on the solute-solvent interaction. The trend of the DeltaDeltaHs values is correlated with that of the DeltaC parameter and with the McReynolds' polarity constants.

Effect of injected sample amount on the shape of chromatographic peaks under condition of linear partition isotherm

In a previous paper a model function was tested in order to approximate the peak shape obtained on non-polar column by injecting different compounds. The simulation of the symmetrical or non-symmetrical shape of gas chromatographic peaks was satisfactory. In this paper, the influence of the amount of injected substance was investigated at different values of inlet pressure and carrier gas velocity, in order to evaluate the relative contribution to the total peak area and shape of the symmetrical distribution due to partition phenomena and of the non-symmetrical and tailing distribution due to adsorption-desorption kinetics. The effect of the molecular mass and of the chain length of compounds belonging to the homologous series of 1-alcohols and n-alkanes on the adsorption phenomena was evaluated.

Prediction of retention times in linear gradient temperature and pressure programmed analysis on capillary columns

The simultaneous temperature and inlet pressure programming (TPP) in gas chromatographic analysis decreases the retention time and the maximum value of temperature required for the elution of high boiling substances. Therefore, compounds sensitive to thermal degradation can be better analysed and column ageing is reduced. However, the empirical choice of proper analysis conditions requires many preliminary runs; this paper describes a procedure for the theoretical prediction of retention times in TPP using few preliminary runs carried out in isobaric and isothermal conditions. The used program permits the prediction of the retention times of the compounds analysed with any different TPP run carried out within the temperature and pressure ranges investigated with the preliminary runs. The influence of various analytical parameters on the accuracy of the prediction values was investigated. The proposed model also predicts the relative position in the chromatogram of closely eluting peaks and the possible coincidence of retention times or inversion of the elution order with changing temperature. It is also possible to foresee the analytical conditions, which offer a baseline separation of all of the peaks of the sample.

Prediction of retention times and efficiency in linear gradient programmed pressure analysis on capillary columns

A method for the prediction of the retention time and the resolution of chromatographic peaks in different experimental conditions by starting from few experimental data measured in isothermal and isobaric analyses was published previously. In this paper, the same mathematical model was implemented for calculating the retention times and the column efficiency in programmed pressure runs. Some models originated from the Golay equation and reported in the literature are compared, and a new modified equation for the calculation of the peak width at half height is proposed. The procedure for the prediction of the retention time and the peak width at half height at programmed pressure of the carrier gas and different column temperature and linear gradient by using retention data of different compounds obtained in few isobaric runs is described. The prediction of the retention time and the separation efficiency of compounds with different polarity gave good results for the programmed pressure runs with linear gradient. The effect of the variation of the initial parameters of the experimental analyses and of the mathematical model on the accuracy of the prediction has been evaluated.

Evaluation and prediction of the shape of gas chromatographic peaks

The evaluation and prediction of the shape of asymmetric gas chromatographic peaks is important as the knowledge of the amount of tailing permits to foresee the resolution between closely eluting peaks and to select the best analytical conditions for an efficient and rapid separation. A model function was tested in order to approximate the true peak shape obtained on non-polar column by injecting different compounds. The trend of the parameters involved in the used equation has been investigated as a function of column temperature and inlet pressure. The reproduction of the symmetrical or asymmetrical shape of gas chromatographic peaks is satisfactory and the method also permits to predict the shape of peaks obtained in different conditions of temperature and pressure.

Novel insertional presenilin 1 mutation causing Alzheimer disease with spastic paraparesis

A four-generation pedigree exhibiting early-onset autosomal dominant Alzheimer disease (AD) with spastic paraplegia, dystonia, and dysarthria due to a novel 6-nucleotide insertional mutation in exon 3 of the presenilin 1 gene (PS1) is described. Serial examinations, PET scans, and autopsy revealed that the mutation in this highly conserved portion of PS1 causes an aggressive dementia that maintains the usual regional hierarchy of disease pathology while extending abnormalities into more widespread brain areas than typically seen in AD.

Prediction of the resolution of capillary columns in different conditions of inlet pressure and temperature

A procedure previously described for the prediction of the plate height of capillary columns operated at different inlet pressure of the carrier gas and at various column temperatures by using few retention data measured under isobaric conditions was modified and improved in order to permit the prediction of the retention times and of the peak widths at various heights. It is therefore possible to calculate the ratio, delta, between the peak width at different heights and the peak width at half height, whose value is used to predict the resolution at different height of two closely eluting peaks. It was found that the delta values do not depend on temperature and inlet pressure and are a characteristic of the used column; they can therefore be used in order to calculate the resolution in any temperature and inlet pressure condition. The method was used to predict the retention time, the peak width and the resolution of polar and non-polar compounds (alkanes, alkenes, chloroalkanes, alcohols, ketones) on capillary columns of different length and polarity by using as the starting data retention and width values measured in three isobaric runs only.