Environmentally friendly technologies to maintain stored paddy rice quality

Exports of processed rice have been increasing every year, as well as legislative restrictions and consumer demand for certified chemical free rice, pressing the rice processing industry to new challenges. The objective of this work was the implementation of a Rice Quality Certification Program. The package includes the association of a rigorous sanitation program and safe environmentally friendly control measures. It was accomplished in a large paddy rice facility with 40 silos during the 2008/09 rice crop. Silo sanitation was done by washing with pressurized water the conveyor belt structure above the silo roof, around the externals walls and thorough aspiration of the aeration system. During silo filling, the lower and top portions of the rice grain were treated with a mixture of diatomaceous earth (DE) and powder deltamethrin. Artificial chilling was applied as soon as the top layer of the grain mass was leveled by insufflating cool air (6 to 8ºC) with a large cooling machine through the aeration system. The grain mass temperature stabilized at about 12-14ºC, and kept this range of temperature for about 60 d. As the temperature of the grain mass increased, mainly on the top layer, aeration was performed with natural air from the cold fronts during the winter months. After 8 months on storage the rice was free of external insects, as proved by the grain sampling just before processing. For the 2009/10 crop season, the rice quality program will be repeated on 60 silos with few adjustments.Keywords: Chilled aeration, Inert dust, Physical insect control, Rice quality maintenance

Spatial distribution of stored grain insects in a rice storage and processing facility in Brazil

This study describes the spatial distribution of stored product insects captured biweekly using foodbaited cage traps in a large rice storage and processing facility, in the state of Rio Grande do Sul, Brazil. Monitoring started in August 2009 and will be carried out for 1 year, the first 5 months of sampling being presented in this study. From end of August 2009 until the end of December 2009, a total of 9893 insects were captured in the 99 cage traps. The most abundant species were: Carpophilus spp. (76%), Typhaea stercorea (8.6%), Ahasverus advena (5.5%), Tribolium castaneum (2.3%), Sitophilus oryzae (2%), Sitophilus zeamais (1.5%), Ephestia spp. (1.2 %), Cryptolestes ferrugineus (1%), Rhyzopertha dominica (0.64%), Oryzaephilus surinamensis (0.6%), Anthicus floralis (0.4%), Lasioderma serricorne (0.25%). The first two species, which make up for 84.6% of the insects collected, are not considered pests in stored grain, rather are attracted by moldy material present in residues or even in the bait material. The other insects, including primary and secondary species, comprised about 15% of the total trapped. The spatial distribution of the most important species infesting rice grain and of the total insect number was analyzed using Surfer 6.04 (Golden software, Golden, CO, USA) and contour maps were constructed to target areas for sanitation. Except for trap 66, located by the rice hulk storage box, the spatial distribution we observed using the contour maps showed that the greatest number of insects was mostly captured in cages placed in the receiving area, around the dryers, as well as outside of the structure where grain residues frequently accumulate. As indicated on the maps for total number of insects, a few isolated infested spots were detected. The parboiled rice area had the least amount of insects, except for trap 61, placed outside the structure. The population of primary and the most important secondary insect species, as well as the overall number of insects, decreased after sanitation and physical control measures were applied. Our observations confirm that insect monitoring is an essential tool for targeting and evaluating the control measures adopted in the quality program of rice storage and processing facilities. Keywords: Insect monitoring; Spatial distribution; Stored grain pests; Stored ric

CHIRAL POLYAMIDOAMINO ACIDS WITH POTENTIAL FOR BIOTECHNOLOGICAL APPLICATIONS

The design of chiral synthetic polymers capable of self-assembling into stable secondary structures represents an attracting approach with important biological applications, such as selective subcellular localization, protein surface mimicry and recognition. Chirality in polymers may be expressed based on the location of the stereogenic centers: i) main-chain chirality; ii) side-chain chirality and iii) self-assembled structures. Synthetic polymers as polyacetylenes, polyole\ufb01nes and polymethacrylamides showing side-chain chirality may be synthesized by radical polymerization processes starting from modified \u3b1-amino acids. In previous work, a new family of biomimetic polymers showing side-chain chirality, named polyamidoamino acids (PAACs), were introduced. The first polymer of this family was named L-ARGO7, derived by the step-wise polyaddition of L-arginine with N,N\u2019-methylenebisacrylamide (MBA). The reaction was carried out in water, at 50\ub0C and pH > 9 for 6 days, yielding a polymer with Mw 488000 and PDI 1.4. L-ARGO7 turned to be highly cytocompatible (IC50 65 8 mg mL-1) and easily internalized in mouse embryo fibroblasts balb/3T3 clone A31 cell line proving, in this respects, to share some of the unique biological properties of polyarginine cell-permeating peptides. The objectives of this work were multiple: to obtain a library of PAACs from the reaction of N,N\u2019-methylenebisacrylamide with various natural \u3b1-amino acids following the same general procedure adopted for the synthesis of L-ARGO7, thus demonstrating the versatility of the synthetic process devised; to study the solution properties of PAACs, namely as acid-base behavior, ionization state, size and viscosity; to elucidate their conformational properties and ability to fold in aqueous media into compact and stable secondary structures; to study the responsiveness of these conformations to external stimuli; to study the fluorescent properties of PAACs from L-tryptophan; most important, to assess the PAAC ability to exhibit chirality-dependent interactions with biomolecules. The PAACs synthesized in this work can be classified based on the structural features of the \u3b1-amino acid residue: i) cationic arginine derived PAACs obtained from D-, L- and D,L-arginine; these polymers are moderately basic, since the guanidine group is internally neutralized by the carboxylate. Basicity is mainly due to the presence of the tert-amine; ii) hydrophobic alkyl-substituted PAACs derived from L-alanine (M-L-Ala), L-valine (M-L-Val) and L-leucine (M-L-Leu); these polymers are obtained by reacting slightly hydrophobic \u3b1-amino acids bearing lateral substituents of increased steric hindrance; iii) polar glutamine-derived PAAC obtained from L-glutamine (M-L-Gln); glutamine was chosen for its ability to form hydrogen bonds as protons donor or acceptor; iv) amphipathic homo- and copolymeric L-tryptophan-based PAACs synthesized from, respectively, L-tryptophan (M-L-Trp) and L-tryptophan/glycine mixtures (M-G-L-Trp); tryptophan was chosen for its fluorescence properties, used to characterized conformational and structural features of homo- and copolymers. EXPERIMENTAL PART: PAACs SYNTHESIS The synthetic procedure of the investigated PAACs is reported in Scheme 1. L-, D- and D,L-PAACs were obtained in variable yield (60-70 %) carrying out the polymerization in aqueous solutions at 50 \ub0C and pH > 9 for 6 days. In no case, traces of hydrolytic degradation or formation of aggregates were seen. After 6 days, solutions were acidified to pH 4, purified by ultrafiltering through membranes with 100 and 5 kDa nominal molecular weight cut-off. The intermediated fractions were freeze-dried and structurally analysed by means of 1H and 13C NMR in D2O, at pH 4.5. Molecular weights (Mw and Mn) was measured by means of size exclusion chromatrographic (SEC) analysis, carried out in 0.1 M TRIS buffer pH 8.00 \ub1 0.05, with 0.2 M NaCl. RESULTS i) ARGO7 and Alkyl-substituted PAACs Circular dichroism (CD) measurements were recorded between 200 \u2013 280 nm in the 3-12 pH interval. Spectra were consistent with the presence of pH-dependent ordered secondary structures, whose changes with pH were rapidly achieved and fully reversible. In addition, conformations resulted thermodynamically stable and reversible in the 3-70\ub0C range. CD spectra were collected at ionic strength up to 2 M NaCl and in presence of denaturating agents, as urea and guanidinium chloride. Conformation of ARGO7 isomers resulted unaffected by ionic strength and presence of denaturants, whereas M-L-Ala, M-L-Val and M-L-Leu conformations changed with the introduction of guanidinium chloride. Molecular dynamics (MD) simulations were performed at Politecnico di Milano (prof. G. Raffaini and F. Ganazzoli) and revealed that ARGO7 and alkyl-substituted PAACs had a compact, coiled structure (Rgs 0.8-1.11 nm). MD showed that PAACs\u2019 main chains were organized into a transoid arrangement characteristics of hairpin-like conformations. Structuring and size were mainly dictated by intramolecular interactions of electrostatic nature in the polymer main chain, with minor dependence from the amino acids side chain. Hydrodynamic radius (Rh) was determined by DLS as a function of pH, time, ionic strength and presence of denaturating agents (urea and guanidinium chloride). Results revealed that these PAACs had monomodal volumetric distributions of 1.5 \ub1 0.3 nm average radius, stable at 25 \ub0C for at least 1 month and unaffected by pH, ionic strength and presence of denaturants. In addition, nanoparticles\u2019 dimensions did not change by increasing the PAACs concentration in the 0.5 \u2013 20 mg mL-1 range, suggesting these polymers may intramolecularly self-assembled into stable single chain nanoparticles. ii) glutamine-derived PAACs Differently from the other PAACs, M-L-Gln Mw and Mn values were more than two times higher than the others. This was tentatively ascribed to the presence of intra- and intermolecular hydrogen bonding, further studied with CD and NMR spectroscopy. CD spectra resulted sensitive to the presence of urea, a protein denaturant known to form H-bonding, with time dependent spectral variations. DOSY, variable-temperature NMR (VT-NMR) and NOESY were used to obtain the structural and conformational features of M-L-Gln. DOSY showed only one diffusion coefficient, from which a Rh of 3.53 nm was calculated. VT-NMR was carried out at pH 4.5 and revealed that side-chain amide groups were involved in the formation of H-bonding, whereas only a small percentage of amides of the MBA backbone did the same. In addition, NOESY experiments measured two NOEs, both involving CH2 next to the tert-amine and CH2 in \u3b2 and \u3b3 position of the glutamine side chain, respectively. Thus, M-L-Gln showed a coiled structure in which glutamine side chain moved closer to the main chain. iii) tryptophan-based PAACs Polymers bearing tryptophan as side substituent were synthesized by Michael-type polyaddition of MBA with L-tryptophan, its isomer, and different molar ratio of L-tryptophan/glycine mixtures. Differently from the other PAACs, these reactions were carried out under nitrogen flux and by portion wise addition of the base to avoid indole oxidation. UV\u2013Vis absorption and scattering of polarized IR beam tests showed all of them to have composition- and pH-dependent solubility. CD studies and DLS measurements were comparable with the other PAACs. CD were consistent with the formation of pH dependent self-assembled structures, whose conformation was dictated by the polymer main chain and its average ionization degree. Rhs resulted stable for at least 1 month, unaffected by pH but, to some extent, sensitive to concentration in the range 1\u201330 mg\ub7mL 121. Photoluminescence analyses, quantum yields, steady state and time-resolved fluorescence were measurements at different pH, polymers concentration and tryptophan content. Results indicated that the photoluminescence properties of tryptophan derived polymers were governed solely by tryptophan. All polymers exhibited pH-dependent quantum yields, lifetimes and emission maximum. Interestingly, fluorescence studies conducted on oxygen-free solution gave comparable results, indicating compact conformations where L-tryptophan moieties were not accessible to the quencher. Also, intermolecular quenching by approaching chains was studied and observed in M-L-Trp and M-G-L-Trp10. iv) L- and D-ARGO7 chiral recognition To assess ARGO7 chiral recognition ability, sodium deoxycholate (NaDC), one of the components of bile salts, was chosen as a chiral model surface. Through a stepwise mechanism, NaDC can form chiral micelles, whose self-assembly behaviour is mainly affected by pH. In particular, NaDC showed three main pH dependent behaviour: homogenous solution (pH > 8), gel phase (pH 7 \u2013 7.5), flocculation and aggregation (pH < 7). Pulsed-gradient spin echo NMR (PGSE-NMR), surface tension, circular dichroism (CD), dynamic light scattering (DLS), zeta potential (ZP) and small-angle neutron scattering (SANS) experiments were carried out on NaDC/L- and NaDC/D-ARGO7 mixtures, to assess chirality-dependent interactions. Surface tension, DLS, zeta potential and PGSE NMR measurements were recorded to characterize NaDC behaviour in solutions (CMC and self-assembly) as a function of pH and concentration and will not be considered in this report. CD measurements were carried out on 5 mg mL-1 of NaDC mixed with 0.5 mg mL-1 of either L-, D- or D,L-ARGO7 solutions, in the 190 \u2013 300 nm range in a 1 mm cell. Prior to the analysis, solutions were corrected to pD (pH of D2O solutions) 9.06, and 7.50. At pD 9.06, the addition of NaDC did not result in any significant modification of the polymers\u2019 spectra, in either L- or D- form of the polymers. Thus, no chiral discrimination could be found at this pH. At pD 7.30, CD spectra of NaDC gel phase showed different pattern upon addition of L- and D-ARGO7, whereas no changes were seen with D,L-ARGO7. Thus, the self-reorganization of NaDC into an ordered gel, was likely due to the chiral recognition of the different isomers. Small-angle neutron scattering (SANS) measurements were carried out at the ISIS Neutron and Muon Source facility (Rutherford Appleton Laboratory in Oxfordshire, UK, under the supervision of Prof. Peter Griffiths) to study chiral recognition, by looking at the conformational modifications of NaDC micelles upon introduction of the different isomeric forms of the polymer, at different pHs and concentrations. SANS collected at pD 8.5 - 8.8 for various NaDC concentrations were consistent with the presence of micelles, described by prolate ellipsoids with polar radius of 22 \u2013 28 \uc5 and equatorial radius of 7 \u2013 10 \uc5. By decreasing pH, NaDC micelles\u2019 structure changed from a prolate ellipsoid (pD 8.80) to an elongated rod (pD 7.30) described by elliptical cylinders of 487.6 \ub1 21.2 \uc5 length and 2.88 \ub1 0.19 axis ratio (Figure. 1a, black curve). NaDC/ARGO7 mixtures were prepared adding 5 mg mL-1 of NaDC to 0.5 mg mL-1 solution of D-, L-, D,L-ARGO7 and an equimolar mixture obtained by mixing L- and D-isomer of the polymer (D-/L-ARGO7). All NaDC/ARGO7 mixtures showed superimposable curves. They were fitted with the same model used for NaDC solutions, that is micelles with prolate ellipsoidal morphology (Figure 1a). Only small changes in the total charge and in the semi-minor and semi-major axis were seen. This confirmed the modest effect of the electrostatic interactions between the two components, ARGO7 and NaDC, and the absence of chiral discrimination. Chiral recognition was then assessed collecting SANS data for 5 mg mL-1 NaDC gels (pD 7.3 \u2013 7.5) with 0.5 mg mL-1 of D-, L-, D,L-ARGO7 or an equimolar mixture composed of 0.5 mg mL-1 D-ARGO7 and 0.5 mg mL-1 L-ARGO7. They showed that NaDC structure was differently affected by the chirality of the polymer (Figure 1b), confirming results obtained from CD spectra. In particular, D-, D,L-ARGO7 and the equimolar mixture changed SANS pattern in the same way. They retained the same rod-like structure of NaDC micelles, albeit with a lower axis ratio (1.51 \ub1 0.41). Different was the case of the NaDC/L-ARGO7 solutions, where L-ARGO7 appeared to trigger the formation of NaDC ellipsoidal clusters. In conclusion, PAACs represent singular examples of synthetic bioinspired chiral polymers that showed potential for biotechnological applications on account of their i) stimuli-responsiveness, ii) self-assembly ability and iii) selective interactions with chiral structures, including biological structures

Self-­‐ordering in solution of a novel polyamidoaminoacid with a chiral arginine side chain

Polyamidoaminoacids (PAAC) are a new class of bioinspired polymers obtained by polyaddition of selected aminoacids with N,N'-methylenebisacrylamide. Here we report some results obtained for the first such polymer, ARGO7, obtained with arginine stereoisomers. The CD spectra of the ARGO7 isomers showed an important and unexpected indication of a self-ordered pH-dependent secondary structure that was however nearly unaffected by temperature, ionic strength and denaturating agents. Theoretical modeling studies of L-ARGO7 carried out with classical Molecular Dynamical simulations showed that it assumed a folded structure with a transoid arrangement of the main chain reminiscent of the protein hairpin motif due to the intramolecular interactions. Torsion angles along the backbone showed a similar distribution at pH 6 and 14 consistent with the similarity of the CD spectra from pH 6 onwards

Intra and interspecific variation assessment in Psocoptera using near spectoscopy

Several species of Psocoptera are associated with and damage grains and other stored products, books, historical documents, and insect collections. Their small size and lack of expressive morphological variation make it a difficult group for species identification. The spectra of adult males and females of 10 psocid species from the genus Liposcelis were obtained by near infrared spectroscopy (NIRS) and analyzed. Each specimen was placed on a diffuse reflectance accessory of a NIR spectrometer to obtain the respective spectrum, using ten replicates for each species or sex. All spectra were analyzed by combined methods of multivariate analysis using the technique of crossed validation for the multivariate models. The analysis discriminated the species without significant overlapping among the species spectral patterns. The NIRS also revealed variation in the metabolomic profile of males and females; however, it is still possible to distinguish the species using only males or females or even from mixed sex samples. NIRS technique proved to be a powerful tool to discriminate species both at intra and interspecific levels based on dispersion spectral patterns of individual specimens. Keywords: Biological systems, Liposcelididae, stored product pests, Vibrational spectroscopy

Molecular Perception for Visualization and Computation: The Proxima Library

Proxima is a molecular perception library designed with a double purpose: To be used with immersive molecular viewers (thus providing any required feature not supported by third party libraries) and to be integrated in workflow managers thus providing the functionalities needed for the first steps of molecular modeling studies. It thus stands at the boundary between visualization and computation. The purpose of the present article is to provide a general introduction to the first release of Proxima, describe its most significant features, and highlight its performance by means of some case studies. The current version of Proxima is available for evaluation purposes at https://bitbucket.org/sns-smartlab/proxima/src/master/

Virtual Reality bridge between Chemistry and Cultural Heritage: the "Sala degli Stemmi" Case Study

In this contribution, we present a multiscale and multidisciplinary VR architecture that aims at creating a common environment where cultural heritage and chemistry meet in order to strengthen the role already played by chemistry in the process of restoration of cultural goods. Our aim is to create a user friendly platform where experts of both fields can share data and ideas in a direct way, in order to achieve deeper insights into cultural goods combining the scientific and historical points of view. As a case study we present the 3D reconstruction of the "Sala degli Stemmi", which is one of the two historical rooms at Palazzo della Carovana in Pisa, presenting a number of artworks that underwent a process of chemical analysis and restoration in 2012. The whole architecture has been developed using the Unity game engine, and it is usable with HTC Vive headsets. The implementation of the VR environment and the potential applications, from both the scientific and educational points of view, are discussed in some detail

Investigation on the Performance of a Compact Three-Fluid Combined Membrane Contactor for Dehumidification in Electric Vehicles

In this paper, the performance of a compact Three-Fluid Combined Membrane Contactor (3F-CMC) is investigated using Computational Fluid Dynamics (CFD), supported and validated with a good agreement by an experimental campaign made on a fully working prototype. This internally-cooled membrane contactor is the core component of a hybrid air conditioning system for electric vehicles (EVs) developed in a successful H2020 project called XERIC. In the adopted numerical approach, the conjugate heat and mass transfer inside the 3F-CMC is described by non-isothermal incompressible flows and vapor transport through a PTFE hydrophobic membrane. The sensitivity of the 3F-CMC performance to air/desiccant flow rates, temperature, humidity, and desiccant concentration is analyzed numerically through the validated CFD codes. According to this study, the moisture removal increases by the inlet humidity ratio, nearly linearly. Under the considered conditions (where the inlet air temperature is 26.2C), when the inlet relative humidity (RH) is 75% the moisture removal is about 450% higher than the case RH = 37%, while the absorption effectiveness declines about 45%. Furthermore, this study shows that the amount of absorbed vapor flux rises by increasing the airflow rate; on the other hand, the higher the airflow rate, the lower is the overall absorption efficiency of the 3F-CMC. This investigation gives important suggestions on how to properly operate a 3F-CMC in order to achieve the requested performance, especially in hot and humid climates