Characterization of a new anthocyanin in black raspberries (Rubus occidentalis) by liquid chromatography electrospray ionization tandem mass spectrometry

Anthocyanin composition of black raspberry (Rubus occidentalis) was studied using high-performance liquid chromatography coupled to photodiode array (PDA) detection and electrospray ionization mass spectrometry (LC-ESI/MS) and tandem mass spectrometry (MS/MS). Pelargonidin 3-rutinoside was isolated and identified in black raspberries using HPLC, UV–Vis spectroscopy, MS, and NMR spectroscopy. No pelargonidin derivative had been previously found in Rubus occidentalis. In addition, the presence and identities of four previously reported anthocyanins (cyanidin 3-glucoside, cyanidin 3-sambubioside, cyanidin 3-rutinoside and cyanidin 3-xylosylrutinoside) were confirmed by HPLC/MS and MS/MS analyses.     

Synthetic peptides as substrate for assaying the proteolytic activity of Lactobacillus helveticus

Four Lactobacillus helveticus strains were studied for proteolytic capacity and general aminopeptidase (AP) and X-Pro dipeptidyl aminopeptidase (DAP) activity. The rate of hydrolysis and the activity against synthetic substrates with N-terminal residues of Arg, Lys, Leu, Glu or Pro, varied markedly among the strains. The X-Pro DAP activity was consistently high. The crude cell-wall and cytoplasm extracts from strain Lb. helveticus ISLC59 were analysed thoroughly for their proteolysis ability by using four synthetic peptide substrates, including alpha(s)1-CN(f1-23). Peptides formed during in vitro hydrolysis of the synthetic substrates by cell wall and cytoplasm preparations were identified by LC-ESI/MS. In doing so, it was possible to infer a prevalent endopeptidase activity splitting Lys7-His8 and Gln13-Glu14 bonds in the cytoplasm, and to deduce a secondary activity, which hydrolysed Glu14-Val15, Leu16-Asn17, Glu18-Asn19 and Lys3-His4 bonds lacking in the cell-wall. The presence of exopeptidases, as mainly AP, DAP, and carboxypeptidase (CPase) was deduced from the formation of several N- and C-terminally truncated peptides sets. The AP activity was higher in the cell-wall layer, where CPase activity was absent. The in vitro assays with cell extracts of the Lb. helveticus ISLC59 strain revealed extensive exopeptidase and endopeptidase activities. In several cases, the hydrolytic system of Lb. helveticus that splits in vitro alpha(s)1-CN(f1-23) peptide bonds was similar to that of Lactococcus lactis. The effects were also compared with those occurring in vivo in hard cheese such as Grana Padano.     

Hybrid solar cells based on MEH-PPV and thin film semiconductor oxides (TiO2, Nb2O5, ZnO, CeO2 and CeO2–TiO2): Performance improvement during long-time irradiation

Performance improvement of hybrid solar cells (HSC) applying five different thin film semiconductor oxides has been observed during long-time irradiation in ambient atmosphere. This behavior shows a direct relation between HSC and oxygen content from the environment. Photovoltaic devices were prepared as bi-layers of thin film semiconducting oxides (TiO₂, Nb₂O₅, ZnO, CeO₂–TiO₂ and CeO₂) and the polymer MEH-PPV, with a final device configuration of ITO/Oxide_{thin film}/MEH-PPV/Ag. The oxides were prepared as thin transparent films from sol–gel solutions. The photovoltaic cells were studied in ambient atmosphere by recording the initial values of open circuit voltage (V_oc) and current density (I_sc). Solar decay curves presented as the measurement of the short circuit current as a function of time, IV curves and photophysical analyses were also carried out for each type of device. Solar cells with TiO₂ thin films showed the best performance with maximum V_oc as high as −0.74 V and I_sc of 0.4 mA/cm². Solar decay analyses showed that the devices require a stabilization period of several hours in order to reach maximum performance. In the case of TiO₂, Nb₂O₅ and CeO₂–TiO₂, the maximum current density was observed after 15 h; for CeO₂, the maximum performance was observed after 30 h. The only exception was observed with devices applying ZnO in which the current density decreased drastically and degraded the polymer in just a couple of hours.     

An Adaptive Questionnaire generation using <Emphasis Type="Italic">learning from fuzzy</Emphasis> and <Emphasis Type="Italic">post clustering</Emphasis> of customers responses: an Experience with Communication Products

A central problem in marketing is the clear understanding of consumer’s choice or preferences. Designing questionnaires and then analyzing the answers of probable customers can achieve this. The traditional approach in the marketing analysis has been the designing of non-adaptive questionnaires, questionnaires that are predetermined and not at all influenced by respondent’s answers. The aim of this paper is to design a questionnaire that is influenced by respondent’s answer through implementation of soft computing and approximate reasoning methodologies. The learning of particular pattern on respondent’s fuzzy responses has also been envisaged in the post-survey (Post-conjoint) and further better clustering of choices and segregation is accomplished. The module of learning and finer clustering from respondent’s choice pattern could be a major pre-requisite for construction of adaptive questionnaires. Further extensions of the soft computing methods for product recommender system have also been mentioned for the design of adaptive questionnaire.     

Increasing the antibacterial effect of lysozyme by immobilization on multi-walled carbon nanotubes

We report a facile strategy to obtain multiwalled carbon nanotubes (MWCNTs) functionalized with covalently bonded lysozyme. The functionalization procedure has been investigated by means of several techniques, including thermogravimetry, Raman spectroscopy, transmission electron microscopy, and cyclic voltammetry. A functionalization of about 1 lysozyme molecule every 4000 carbon atoms is obtained. The modified lysozyme-CNTs nanocomposite shows a significant increase of the antibacterial activity towards the Gram-positive S. aureus if compared with lysozyme in solution.     

Q fever endocarditis in Romania: the first cases confirmed by direct sequencing

Infective endocarditis (IE) is a serious, life-threatening disease with highly variable clinical signs, making its diagnostic a real challenge. A diagnosis is readily made if blood cultures are positive, but in 2.5 to 31% of all infective endocarditis cases, routine blood cultures are negative. In such situations, alternative diagnostic approaches are necessary. Coxiella burnetii and Bartonella spp. are the etiological agents of blood culture-negative endocarditis (BCNE) most frequently identified by serology. The purpose of this study is to investigate the usefulness of molecular assays, as complementary methods to the conventional serologic methods for the rapid confirmatory diagnostic of Q fever endocarditis in patients with BCNE. Currently, detection of C. burnetii by culture or an antiphase I IgG antibody titers >800 represents a major Duke criterion for defining IE, while a titers of >800 for IgG antibodies to either B. henselae or B. quintana is used for the diagnosis of endocarditis due to Bartonella spp. We used indirect immunofluorescence assays for the detection of IgG titers for C. burnetii, B. henselae and B. quintana in 57 serum samples from patients with clinical suspicion of IE. Thirty three samples originated from BCNE patients, whereas 24 were tested before obtaining the blood cultures results, which finally were positive. The results of serologic testing showed that nine out of 33 BCNE cases exhibited antiphase I C. burnetii IgG antibody titer >800, whereas none has IgG for B. henselae or B. quintana. Subsequently, we used nested-PCR assay for the amplification of C. burnetii DNA in the nine positive serum samples, and we obtained positive PCR results for all analyzed cases. Afterwards we used the DNA sequencing of amplicons for the repetitive element associated to htpAB gene to confirm the results of nested-PCR. The results of sequencing allowed us to confirm that C. burnetii is the causative microorganism responsible for BCNE. In conclusion, the nested PCR amplification followed by direct sequencing is a reliable and accurate method when applied to serum samples, and it may be used as an additional test to the serological methods for the confirmatory diagnosis of BCNE cases determined by C. burnetii.     

Optimisation of microwave-assisted acid digestion for the purification of supported carbon nanotubes

Experimental optimisation of microwave-assisted acid digestion for supported carbon nanotube (CNT) purification is reported. Process variables including ramp rate, temperature, duration, scalability, acid type, volume and concentration were investigated using thermogravimetric, Fourier transform infra-red and Raman spectroscopy performance metrics. Key factors in purification were temperature, duration and acid. HNO₃ damaged CNTs and introduced carboxyl and C–O functional groups. HCl and H₂SO₄ achieved similar impurity removal but, despite the incorporation of sulphur-based functional groups, H₂SO₄ was preferred due to a more homogeneous product. Concentration and volume variables could be condensed into a single factor – the stoichiometric excess of acid to impurities – for process simplification and to permit direct literature comparison. The scalable optimised process increased CNT purity from ∼22 wt% to > 95 wt% with negligible damage in a single 15 min isothermal treatment at 230 °C with a H₂SO₄ excess of 4.5 times the required stoichiometry (1 M).     

Real Time PCR for the detection and discrimination of cereal contamination in gluten free foods

Real-time PCR methods, using melting curve analysis for product identification, were established for the specific discrimination of wheat, rye, barley and oats in food samples. Specific primers targeting cereal prolamin genes were chosen for the amplification. The lengths of the amplicons varied between 104 and 181 base pairs and the melting point between 81.2 and 85.0 °C. The specificity of the wheat PCR was shown for spring and autumn wheat but also for durum wheat, spelt wheat and kamut. The methods were applied for final food products and for detection of toxic cereal contamination in oat samples. The results of the analysis were compared with those obtained with an established enzyme immuno assay for gluten analysis. The PCR methods give a good correlation with the protein assay and are rapid and sensitive. The PCR methods can thus be used as confirmatory methods in food analysis of gluten-free and naturally gluten-free foods.