Search

In this study, for the first time, six different hazelnut cultivars, characterized by different carpological traits (diameter, volume, weight, density, shell thickness, shape index, empty volume between kernel and shell), were utilized for conducting 60 experiments in a lab-scale convective dryer, in which different drying air conditions (temperatures: 20 °C, 35 °C, 50 °C; relative humidity: 20%, 40%, 60%; airflow: 0.5 m/s) were explored with a Design of Experiment approach. The obtained drying curves where mathematically modeled and, among the tested kinetic models, the Fick's equation proved to best fit the drying data and was chosen to estimate the equilibrium moisture content (Me) and the drying rate (k) for each experiment, based on the studied variables. The k parameter was found to be greatly affected (p

BACKGROUND The aim of this study is to investigate the feasibility of a ‘holistic’ approach, using near infrared (NIR) spectroscopy and electronic devices (electronic nose and electronic tongue), as instrumental tools for the classification of different coffee varieties. Analyses were performed on green coffee, on ground roasted coffee and on coffee beverage. Principal component analysis was applied on spectral and sensory data to uncover correlations between samples and variables. After variable selection, linear discriminant analysis was used to classify the samples on the basis of the three coffee classes: Robusta, natural Arabica and washed Arabica. RESULTS Linear discriminant analysis demonstrates the practicability of this approach: the external test set validation performed with NIR data showed 100% of correctly classified samples. Moreover, a satisfying percentage of correct classification in cross-validation was obtained for the electronic devices: the average values of correctly classified samples were 81.83% and 78.76% for electronic nose and electronic tongue, respectively. CONCLUSION NIR spectroscopy was shown to be a very reliable and useful tool to classify coffee samples in a fast, clean and inexpensive way compared to classical analysis, while the electronic devices could assume the role of investigating techniques to depict the aroma and taste of coffee samples. © 2014 Society of Chemical Industry

Plasma polymerized acrylic acid (AA) coatings were deposited on poly(lactic acid) (PLA) films in various gas atmospheres during the pre-treatment of PLA and the deposition of AA, respectively. Therefore, this work was twofold: the argon pretreated PLA films followed by a deposition in argon were investigated against the mixture of argon and oxygen pretreated ones under the same deposition conditions; the plasma deposition of AA operating in different atmospheres (argon, oxygen and nitrogen) was employed to modify the pretreated PLA in oxygen. Chemical and physical changes on the plasma-treated surfaces were examined using contact angle, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM) and attenuated total reflection infrared (ATR-FTIR) analysis. The results showed that the discharge gas can have a significant influence on the chemical composition of the PLA surfaces: oxygen plasmas introduced oxygen-containing groups in company with surface etching in pretreatment and deposition, while argon discharges was able to achieve much better hydrophilic behavior and high retention ratio of poly(acrylic acid) (PAA) coating before and after washing in water.

Objective: This study evaluated the variation of conversion degree (DC) in the 12 hours following initial photoactivation of a low-shrinkage composite resin (Venus Diamond). Material and Methods: The conversion degree was monitored for 12 hours using Attenuated Total Reflection (ATR) F-TIR Spectroscopy. The composite was placed in 1 or 2 mm rings and cured for 10 or 20 seconds with a LED lamp. ATR spectra were acquired from the bottom surface of each sample immediately after the initial photoactivation (P=0), 30 minutes (P=0.5) and 12 hours after photoactivation (P=12) in order to obtain the DC progression during the post-curing period. Interactions between thickness (T), irradiation time (I) and post-curing (P) on the DC were calculated through ANOVA testing. Results: All the first order interactions were statistically significant, with the exception of the T-P interaction. Furthermore, the shift from P=0 to P=0.5 had a statistically higher influence than the shift from P=0.5 to P=12. The post-curing period played a fundamental role in reaching higher DC values with the low-shrinkage composite resin tested in this study. Moreover, both the irradiation time and the composite thickness strongly influenced the DC. Conclusions: Increased irradiation time may be useful in obtaining a high conversion degree (DC) with a low-shrinkage nano-hybrid composite resin, particularly with 2 mm composite layers.

The roasting colour of the coffee beans and the varietal composition of the blends are key factors for the development of the sensorial properties of the coffee brew. The former is a critical control parameter for the roasting process and allows to verify quickly the performance of the roasting, being directly related to the desired organoleptic characteristics of the beverage. The varietal composition is a paramount factor for quality, where Arabica species shows a better sensorial profile in comparison to Robusta, with a substantial difference in the selling price. Near infrared spectroscopy associated with chemometrics represents a screening tool when a fast determination of these two coffee parameters is needed. The focus of the work is the elaboration of a unique model for the simultaneous determination of the roasting degree and of Arabica/Robusta ratio. The PLS algorithm was applied and a completely independent external set was used for the validation. A root mean square errors equal to 1.28 A.U. and 4.34% (w/w) was obtained, respectively for the colour and the Arabica content in the blends.

Highly bioactive glass coatings were successfully achieved by applying a newly developed bioactive glass layer having a low Ca/P ratio on a ZrO 2 -3%Y 2 O 3 ceramic substrate. The thermal properties of the glass allowed covering zirconia substrates both by amorphous and glass-ceramic coatings. The coatings exhibited 345 μm thickness and were free from surface cracks, highlighting the good compatibility between the glass and the substrate in terms of expansion coefficient matching. The synthesized materials achieved the formation of a crystalline carbonate apatite layer after 3 days soaking in SBF solution. Although the slight diffusion of the amorphous and glass-ceramic coatings through the ZrO 2 -3%Y 2 O 3 support (≤20 μm and ≤100 μm, respectively), the rate of formation of carbonate apatite layer was maintained in comparison with the native glass alone, constituting a promising material for application as dental prosthetic devices.

Poly(lactic acid) (PLA) based nanocomposites based on 5 wt.% of an organically modified montmorillonite (CLO), unmodified sepiolite (SEP) and organically modified zirconium phosphonate (ZrP) were obtained by melt blending. Wide angle X-ray scattering (WAXS) and scanning electron microscopy (SEM) analysis showed a different dispersion level depending on the type and functionalisation of nanoparticles. Differenctial scanning calorimetric (DSC) analysis showed that PLA was able to crystallize on heating, and that the addition of ZrP could promote extent of PLA crystallization, whereas the presence of CLO and SEP did not significantly affect the crystallization on heating and melting behaviour of PLA matrix. Dynamic Mechanicl Thermoanalysis (DMTA) results showed that addition of all nanoparticles brought con- siderable improvements in E! of PLA, resulting in a remarkable increase of elastic properties for PLA nanocomposites. The melt viscosity and dynamic shear moduli (G!,G") of PLA nanocomposites were also enhanced significantly by the presence of CLO and SEP, and attributed to the formation of a PLA/nanoparticle interconnected structure within the polymer matrix. The oxygen permeability of PLA did not significantly vary upon addition of SEP and ZrP nanoparticles. Only addition of CLO led to about 30% decrease compared to PLA permeability, due to the good clay dispersion and clay platelet-like mor- phology. The characteristic high transparency of PLA in the visible region was kept upon addition of the nanoparticles. Based on these achievements, a high potential of these PLA nanocomposites in sustainable packaging applications could be envisaged.

Hydrogen reservoirs based on porous silicon (PS) nanostructures are considered. Silicon-based hydrogen tanks are believed to be applicable for portable device energy supply and compatible with micro-sources of energy of new generation. Stain etching of silicon powder to produce PS is studied as a technology alternative to conventional electrochemical etching and application of the PS powder for hydrogen production is also described. Size selection of initial Si micro-particles constituting the powders was carried out by sedimentation technique. Hydrogen content in PS was investigated by FTIR spectroscopy. Extraction of hydrogen in water environment in presence of small amount of NH3 as catalyst was shown to have advantages such as safety and tunability, additional production of hydrogen from water dissociation, and a possibility to characterize PS as a hydrogen source material in terms of hydrogen effective shell and crystalline core conception.

Silver nanoparticles are obtained through immersion plating of porous Si in AgNO3 solutions and thermal decomposition of Ag nitrate in oxidized pSi. The efficiency of nanostructures as Surface Enhanced Raman Scattering substrates is checked on a Cyanine dye evidencing detectable concentrations as low as 107 M. The substrate efficiency is strictly related to the Ag particle morphology, which could yield to either Localized Surface Plasmons coupled to individual particles or to inter-particle short-range interaction

Porous silicon samples have been subjected to plasma treatments under ammonia atmosphere. The samples were characterized by IR, UV-Visible reflectance and stationary photoluminescence spectroscopies. A deep modification concerning both surface and bulk properties of silicon nanocrystals is clearly observed. In particular, the nanocrystals surface is covered by amino groups, as checked by IR spectroscopy, whilst bulk modification can be inferred by UV-Visible reflectance and luminescence characterizations, in particular for high porosity. The results demonstrate that plasma assisted nitridation yields to a controllable modification of the optical and chemical properties of porous silicon, without need of thermal annealing and/or wet chemical processes. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Silver nanocrystallites are obtained through immersion of porous silicon samples in AgNO 3 solutions and a successive thermal annealing. The efficiency of nanostructures as surface enhanced Raman scattering (SERS) substrates is checked on cyanine-based dyes and horseradish peroxidase, evidencing detectable concentrations as low as 10 −7 to 10 −8 M. The substrate efficiency is strictly related to the Ag particle morphology, which could yield to either local surface plasmons (LSP) coupled to individual particles or to inter-particle short-range interaction.

In this work, sintered pellets of a silica-based bioactive glass were dip-coated with a biocompatible natural-derived polymer in order to investigate the influence of the organic coating on the glass bioactivity. After the sintering process optimization, uncoated and coated pellets have been characterized by means of scanning electron microscopy with energy dispersive spectroscopy (SEM, EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and pH measurements, after the immersion in a simulated body fluid (SBF). An increased apatite forming ability and a better control of the pH during soaking of the samples in SBF were observed in the presence of the biopolymer. This result opens a new insight on the simple fabrication of highly bioactive hybrid inorganic-organic materials for medical applications.

The properties of porous silicon Fabry–Perot microcavities impregnated with oxazine, a fluorescent dye, are investigated by photoluminescence and reflectance spectroscopy. The emission spectrum of the dye is noticeably modified by the cavity structures, being both the peak intensity increased and the linewidth narrowed, while the peak position coincides with that measured by UV–Vis reflectance. The results suggest that is possible, by simple methods, to prepare optically active hybrid materials integrating the properties of the inorganic host structure and of the organic guest.

The aim of this study is to investigate the feasibility of a 'holistic' approach, using near infrared (NIR) spectroscopy and electronic devices (electronic nose and electronic tongue), as instrumental tools for the classification of different coffee varieties. Analyses were performed on green coffee, on ground roasted coffee and on coffee beverage. Principal component analysis was applied on spectral and sensory data to uncover correlations between samples and variables. After variable selection, linear discriminant analysis was used to classify the samples on the basis of the three coffee classes: Robusta, natural Arabica and washed Arabica.Linear discriminant analysis demonstrates the practicability of this approach: the external test set validation performed with NIR data showed 100% of correctly classified samples. Moreover, a satisfying percentage of correct classification in cross-validation was obtained for the electronic devices: the average values of correctly classified samples were 81.83% and 78.76% for electronic nose and electronic tongue, respectively.NIR spectroscopy was shown to be a very reliable and useful tool to classify coffee samples in a fast, clean and inexpensive way compared to classical analysis, while the electronic devices could assume the role of investigating techniques to depict the aroma and taste of coffee samples.

An effective and physiological bone integration and absence of bacterial infection are essential for a successful orthopaedic or dental implant. A titanium surface able to actively promote bone bonding and avoid microbial colonization represents an extremely interesting challenge for these purposes. An innovative and patented surface treatment focused on these issues is described in the present paper. It is based on acid etching and subsequent controlled oxidation in hydrogen peroxide, enriched with silver ions. It has been applied to commercially pure titanium (Ti-cp) and alloy Ti6Al4V. The chemistry and morphology of the surfaces are modified by the treatment on a nanoscale: they show a thin oxide layer with porosity on the nanoscale and silver particles (few nanometers in diameter), embedded in it. These features are effective in order to obtain antibacterial and bioactive titanium surfaces.

Identification of harvest date plays a key role in the agro-food chain as the quality of fruit depends on the right harvesting time and appropriate storage conditions during the postharvest period. Destructive techniques, such as the use of some ripening parameters, suffer from several drawbacks that highlight the need for reliable non-destructive tools to determine ripeness stage. This work is focused on the study of ripening of red apples (‘Scarlet’), with the aim of better identifying the harvest date, by means of non-destructive analysis, through the characterization of each fruit ripening stage on the trees, with classical methods as a reference. UV–Vis analysis was applied in diffuse reflectance (DR) mode to monitor variations in the chlorophyll content of the skin of red apples during ripening on the tree, since the colour variation in red apples is difficult to observe during ripening, and the ground colour cannot be considered a valid tool to identify ripening. On the other hand, variation in the chlorophyll content, measured by means of in situ DR-UV–Vis spectroscopy, is a reliable indicator of the ripeness stage. The novelty of this work is that a backward interval–GA–partial least squares (PLS) model, based both on NIR and UV–Vis data, was used to predict the optimal harvesting time in a direct way. We also established an overview of fruit maturation through a comparison with UV–Vis analysis and calibrations of the ripening parameters.

The coupling of artificial materials and biological molecules is an interesting strategy in order to obtain specific and effective methods to detect signals in tumor cells and develop biological therapies in cancer treatment. A bioactive and ferrimagnetic glass ceramic (named SC45) was selected for the functionalization in this research. Two model biological molecules have been employed for the grafting: gallic acid (a phenolic acid known for its antioxidant, antibacterial and anticancer activities) and folic acid (a B group vitamin involved in cell growth and repair and often employed as cancer cell marker). Direct grafting to surface exposed hydroxyls group has been selected for gallic acid while silanization and carbodiimide activation has been used for folic acid coupling. XPS and FTIR techniques were adopted to evaluate the effect of surface modifications.

Titanium and its alloys represent the gold standard for orthopaedic and dental prosthetic devices, because of their good mechanical properties and biocompatibility. Recent research has been focused on surface treatments designed to promote their rapid osteointegration also in case of poor bone quality. A new surface treatment has been investigated in this research work, in order to improve tissue integration of titanium based implants. The surface treatment is able to induce a bioactive behaviour, without the introduction of a coating, and preserving mechanical properties of Ti6Al4V substrates (fatigue resistance). The application of the proposed technique results in a complex surface topography, characterized by the combination of a micro-roughness and a nanotexture, which can be coupled with the conventional macro-roughness induced by blasting. Modified metallic surfaces are rich in hydroxyls groups: this feature is extremely important for inorganic bioactivity (in vitro and in vivo apatite precipitation) and also for further functionalization procedures (grafting of biomolecules). Modified Ti6Al4V induced hydroxyapatite precipitation after 15 days soaking in simulated body fluid (SBF). The process was optimised in order to not induce cracks or damages on the surface. The surface oxide layer presents high scratch resistance.

The synthesis of porous silicon-based photonic structures for bio-sensing applications has been widely investigated in the last years. Thanks to its spongiform structure, porous silicon can efficiently host many organic molecules dispersed in solutions having proper chemical affinity. Fluorescent emission of organic-dyes embedded in porous silicon can be enhanced if a photonic structure like a Fabry–Perot resonator is employed as a host solid matrix. In this work we present experimental evidence of a fluorescence enhancement effect obtained by means of doubly resonant microcavities tuned on both the excitation and the emission wavelengths. The use of doubly resonant cavities allows both a resonant excitation of dyes and a resonant amplification of the emission. We demonstrate that small concentrations of fluorescent dyes down to few picomoles can be detected. The bio-sensing capabilities of such a structure are tested on larger molecules of fluorescein-labelled protein A, yielding to an evident lowering of the detection limit by 2 orders of magnitude.