Influence of Feeding and Oviposition by Phytophagous Pentatomids on Photosynthesis of Herbaceous Plants

Feeding by herbivorous insects may change photosynthetic activity of host plants. We studied how feeding and oviposition by herbivorous stink bugs, Murgantia histrionica and Nezara viridula (Heteroptera: Pentatomidae), affect photosynthetic parameters of Brassica oleracea (savoy cabbage) and Phaseolus vulgaris (French bean). First, we measured photosynthetic gas exchange, chlorophyll fluorescence imaging, and emission of induced volatile organic compounds (VOC) immediately after feeding and during a post-feeding period. Photosynthesis decreased rapidly and substantially in B. oleracea and P. vulgaris infested by feeding bugs. Stomatal conductance did not decrease proportionally with photosynthesis; instead, inhibition of photosynthesis likely was due to a reduced diffusion of CO₂ in the mesophyll. We also measured the impact of oviposition per se and oviposition associated with feeding on photosynthetic parameters. A surprisingly large inhibition of photosynthesis was detected in cabbage leaves in response to oviposition by M. histrionica, even when oviposition was not associated with feeding activity. High resolution chlorophyll fluorescence imaging revealed that the damage to photochemistry caused by feeding and oviposition was restricted to the attacked areas. By contrast, the photochemical yield increased temporarily in the unaffected areas of the attacked leaves, indicating the onset of a compensatory response. Measurement of volatile organic compounds (VOC) revealed that feeding-damaged plants did not emit detectable amounts of VOC, indicating cellular damage (methanol and green leaf volatiles). However, feeding by M. histrionica induced emission of mono- and sesquiterpenes in savoy cabbage leaves. The different time-course of the induction of these two classes of terpenes may reflect the induction of two different biosynthetic pathways and indicate different roles of these terpenoids in tritrophic interactions.     

Preparation and Characterization of Nanostructured TiO2/Epoxy Polymeric Films

Summary: Titania‐containing coatings were prepared by cationic photopolymerization of an epoxy resin either by dispersion of preformed TiO₂ nanoparticles or by their in‐situ generation through a sol‐gel dual‐cure process. The kinetics of photopolymerization was evaluated by real‐time FT‐IR, studying the effect of the TiO₂ concentration. The properties of cured films were investigated, showing an increase of hydrophilicity on the surface of the coatings with increasing TiO₂ content. TEM analysis demonstrated that it is possible to achieve a significantly better control of the dispersion of the inorganic particles within the organic matrix by in‐situ generation of TiO₂, thus completely avoiding macroscopic phase separation and obtaining homogeneous, transparent coatings.

Bright‐field TEM micrograph for TIP20 dual‐cured film.     

Surface modifications induced in 316L steel by laser peening and shot-peening. Influence on pitting corrosion resistance

The influence of laser peening (LP) on the electrochemical behavior of AISI type 316L stainless steel in a saline environment was evaluated. Surface modifications were investigated as they might have beneficial effects on the corrosion behaviour. Low residual stress and work hardening levels were found, when compared with a conventional shot-peening (SP) treatment, mainly because of the absence of martensite transformation in the case of LP. Surface changes were accompanied by small roughening effects and a global preservation of the surface chemistry after treatment. Therefore, electrochemical tests performed on samples after LP and SP treatments showed increases in rest potentials, reductions of passive current densities and anodic shifts of the pitting potentials evidenced by a stochastic approach of pitting. The better pitting resistance was observed after LP treatment, which seems to reflect a reduction or an elimination of active sites for pitting at lower potentials. Even though the deleterious surface state of shot peened surfaces possibly counterbalances the beneficial influence of residual stresses, a beneficial influence of mechanical surface treatments has been demonstrated regarding the localized corrosion properties.     

A Strip-Yield algorithm for the analysis of closure evaluation near the crack tip

“Plasticity-induced crack closure” phenomenon is the leading mechanism of different effects (R-ratio, overload retardation, … ) acting on crack growth rate in many metallic materials. Experimental tests are carried out to quantify the physical phenomenon, while Strip-Yield analytical models have been developed for predicting life of components. In the present work, an additional module to be applied to a Strip-Yield model is proposed in order to derive the strains near the crack tip. Particularly, the module is based on the Westergaard’s elastic complex potential. The presented algorithm allowed us to obtain the correlation between “local compliance” experimental results and the corresponding Strip-Yield analyses. This method can be taken as a semi-analytical procedure for calibrating the constraint factor, i.e., the most delicate parameter for Strip-Yield models.     

Spatial Networks of Hybrid I/O Automata for Modeling Excitable Tissue

We propose a new biological framework, spatial networks of hybrid input/output automata (SNHIOA), for the efficient modeling and simulation of excitable-cell tissue. Within this framework, we view an excitable tissue as a network of interacting cells disposed according to a 2D spatial lattice, with the electrical behavior of a single cell modeled as a hybrid input/ouput automaton. To capture the phenomenon that the strength of communication between automata depends on their relative positions within the lattice, we introduce a new, weighted parallel composition operator to specify the influence of one automata over another.The purpose of the SNHIOA model is to efficiently capture the spatiotemporal behavior of wave propagation in 2D excitable media. To validate this claim, we show how SNHIOA can be used to model and capture different spatiotemporal behavior of wave propagation in 2D isotropic cardiac tissue, including normal planar wave propagation, spiral creation, the breakup of spirals into more complex (potentially lethal) spatiotemporal patterns, and the recovery of the tissue to the rest via defibrillation.     

Lessons learned from a complicated case of cephalic obstructive chronic pancreatitis

The authors report the complex case of a 51 year-old man admitted to his local hospital for gallbladder and common bile duct lithiasis, 1 year before admission to our hospital. There, he was treated by cholecystectomy and transduodenal biliary sphincteroplasty. He was readmitted after 3 months because of a painful episode and was discharged with the diagnosis of "relapsing acute pancreatitis in chronic pancreatitis." At our hospital, he underwent laparotomy and revision of the previous transduodenal biliary sphincteroplasty. Pancreatic sphincteroplasty and septectomy were also performed. The night after surgery, the patient suffered from acute post-operative pancreatitis complicated by severe hemorrhage due to erosion of the superior pancreaticoduodenal arteries, treated with gastroduodenal artery embolization by tungsten coils. Three months later, the patient suffered from another acute episode. An endoscopic retrograde colangio pancreatography (ERCP) showed the complete patency of the sphincteroplasties but clearly identified the persistence of a severe cephalic stricture. Therefore, the patient was readmitted to our hospital and underwent another laparotomy. A pylorus-preserving pancreaticoduodenectomy (PPPD) was performed. The post-operative course was uneventful and at 14 months follow-up the patient was in good health. The discussion focuses on the surgical treatment of chronic pancreatitis with cephalic Wirsung duct stenosis, stressing the increasing role of PPPD as a first-choice option.     

The contribution of proteomic studies in humans,animal models,and after antidepressant treatments to investigate the molecular neurobiology of major depression

The neurobiological basis of major depressive disorder (MDD) is only partially understood. The proposed hypotheses postulate dysregulations of monoaminergic and other neurotransmitter pathways, impaired stress responses, insufficient neurogenetic and neurotrophic processes generating maladaptive neuroplasticity, inappropriate inflammatory and metabolic responses. Proteomic approaches can provide useful contributions to the investigation of the molecular neurobiology of MDD due to their open-ended nature. Studies performed in brain regions of MDD patients which had received antidepressant (AD) treatment showed that affected proteins mainly belonged to energy pathways, transport of molecules, signaling, and synaptic transmission. Studies performed in animal models offer the advantage of more controlled experimental conditions at the expense of potential loss in relevance. The design of proteomic investigations included experiments carried out in MDD models, in naive animals treated with ADs, and in animal models subjected to AD treatments. A comparison of results suggested an overlap of several modulated pathways between MDD patients and animal models. Examples include the regulation of energy metabolism, especially oxidative phosphorylation and glycolysis, signal transduction pathways, including calcium-calmodulin kinase II, synaptic proteins, and cytoskeletal proteins. Nevertheless, the paucity of studies performed in human brains requires additional studies to confirm the correspondence.     

Nonlinear complementary filters on the special linear group

This article proposes a nonlinear complementary filter for the special linear Lie-group SL(3) that fuses low-frequency state measurements with partial velocity measurements and adaptive estimation of unmeasured slowly changing velocity components. The obtained results have direct application on the problem of filtering a sequence of image homographies acquired from low-quality video data. The considered application motivates us to derive results that provide adaptive estimation of the full group velocity or part of the group velocity that cannot be measured from sensors attached to the camera. We demonstrate the performance of the proposed filters on real world homography data.     

Reactive blending methodologies for biopol

Multicomponent polymeric systems containing Biopol as one of the phases are described as obtained according to two different procedures: radical polymerization of an acrylic polymer in the presence of Biopol, and melt-mixing of Biopol with polycaprolactone in the presence of peroxide. The decomposition of peroxide causes, in both cases, the formation of intergrafted species responsible for interfacial activity and compatibilization. The results of chemical, chemical–physical, morphological and mechanical tests, confirming the occurrence of such interactions, are reported.