518 research outputs found
The potential immune alterations in insect pests and pollinators after insecticide exposure in agroecosystem
Agroecosystems are the habitat of pests and beneficial insects from different orders, which are
exposed to agro-practices, especially treatments with chemicals. Insecticides are a wide group of
chemicals used in agroecosystems that affect insect ecology and physiology in different ways. Among
physiological components affected by insecticides, the immune system (IS) is an important one,
enabling insects to resist against invading microorganisms and parasitoids thanks to the action of
hemocytes and humoral components. So the determination of any immune alterations should be
considered as a critical issue in insecticide application within agroecosystems. Insecticides of synthetic
or natural origin, e.g. insect growth regulators (IGRs) and botanicals, are frequently cytotoxic and alter
hemocyte morphology and number, impairing cellular-based immune responses in addition to humeral
responses. Exposure of pollinators to neurotoxin insecticides like neonicotinoids may inhibit the
immune-related transcription factor, NF- B, with a negative impact on the expression of antimicrobial
peptides, melanization and clotting. In contrast, some IGRs may have enhancing effects on hemocyte
spreading mainly plasmatocytes and cellular-based immune responses. Chemical insecticides have
several impacts on the physiology of insects in which immune modulation is one of the most important
cases because any alteration may alter their ability to respond toward invading pathogens and directly
their survival. This is more severe once pollinators are in contact with chemicals because of the
presence of several pathogenic agents that directly influence their performance
Role of heat and mechanical treatments in the fabrication of superconducting Ba0.6K0.4Fe2As2 ex-situ Powder-In-Tube tapes
Among the recently discovered Fe-based superconducting compounds, the
(K,Ba)Fe2As2 phase is attracting large interest within the scientific community
interested in conductor developments. In fact, after some years of development,
critical current densities Jc of about 105 A/cm2 at fields up to more than 10 T
have been obtained in powder in tube (PIT) processed wires and tapes. Here we
explore the crucial points in the wire/tape fabrication by means of the ex-situ
PIT method. We focus on scaling up processes which are crucial for the
industrial fabrication. We analyzed the effects on the microstructure of the
different heat and mechanical treatments. By an extensive microstructural
analysis correlated with the transport properties we addressed the issues
concerning the phase purity, the internal porosity and crack formation in the
superconducting core region. Our best conductors with a filling factor of about
30 heat treated at 800 C exhibited Tc = 38 K the highest value measured in such
kind of superconducting tape. The microstructure analysis shows clean and well
connected grain boundaries but rather poor density: The measured Jc of about 3
x 10^4 A/cm2 in self-field is suppressed by less than a factor 7 at 7 T. Such
not yet optimized Jc values can be accounted for by the reduced density while
the moderate in-field suppression and a rather high n-factor confirm the high
homogeneity and uniformity of these tapes
The immuneregulator role of neprilysin (NEP) in invertebrates
Neprilysin (NEP) represents an important enzyme in both vertebrates and invertebrates. In the present report we have focused our attention to invertebrates. In particular, a structure related to CD10/NEP as well as its activity in different tissues, such as immunocytes, nervous tissue and muscle of various species were detected. Moreover, the role played by the enzyme in the interactions between host and parasite has also been reported. The findings indicate that NEP immunoregulation is a well-balanced process that, with appropriate physiological and homeostatic responses to challenges, allows the survival and well-being of the species
Pomacea canaliculata ampullar proteome: A nematode-based bio-pesticide induces changes in metabolic and stress-related pathways
Pomacea canaliculata is a freshwater gastropod known for being both a highly invasive species and one of the possible intermediate hosts of the mammalian parasite Angiostrongylus cantonensis. With the aim of providing new information concerning P. canaliculata biology and adaptability, the first proteome of the ampulla, i.e., a small organ associated with the circulatory system and known as a reservoir of nitrogen-containing compounds, was obtained. The ampullar proteome was derived from ampullae of control snails or after exposure to a nematode-based molluscicide, known for killing snails in a dose-and temperature-dependent fashion. Proteome analysis revealed that the composition of connective ampulla walls, cell metabolism and oxidative stress response were affected by the biopesticide. Ultrastructural investigations have highlighted the presence of rhogocytes within the ampullar walls, as it has been reported for other organs containing nitrogen storage tissue. Collected data suggested that the ampulla may belong to a network of organs involved in controlling and facing oxidative stress in different situations. The response against the nematode-based molluscicide recalled the response set up during early arousal after aestivation and hibernation, thus encouraging the hypothesis that metabolic pathways and antioxidant defences promoting amphibiousness could also prove useful in facing other challenges stimulating an oxidative stress response, e.g., immune challenges or biocide exposure. Targeting the oxidative stress resistance of P. canaliculata may prove helpful for increasing its susceptibility to bio-pesticides and may help the sustainable control of this pest’s diffusion
Effect of grain refinement on enhancing critical current density and upper critical field in undoped MgB2 ex-situ tapes
Ex-situ Powder-In-Tube MgB2 tapes prepared with ball-milled, undoped powders
showed a strong enhancement of the irreversibility field H*, the upper critical
field Hc2 and the critical current density Jc(H) together with the suppression
of the anisotropy of all of these quantities. Jc reached 104 A/cm2 at 4.2 K and
10 T, with an irreversibility field of about 14 T at 4.2 K, and Hc2 of 9 T at
25 K, high values for not-doped MgB2. The enhanced Jc and H* values are
associated with significant grain refinement produced by milling of the MgB2
powder, which enhances grain boundary pinning, although at the same time also
reducing the connectivity from about 12% to 8%. Although enhanced pinning and
diminished connectivity are in opposition, the overall influence of ball
milling on Jc is positive because the increased density of grains with a size
comparable with the mean free path produces strong electron scattering that
substantially increases Hc2, especially Hc2 perpendicular to the Mg and B
planes.Comment: 26 pages, 9 figures, submitted to J. Appl. Phy
Evidence for length-dependent wire expansion, filament dedensification and consequent degradation of critical current density in Ag-alloy sheathed Bi-2212 wires
It is well known that longer Bi-2212 conductors have significantly lower
critical current density (Jc) than shorter ones, and recently it has become
clear that a major cause of this reduction is internal gas pressure generated
during heat treatment, which expands the wire diameter and dedensifies the
Bi-2212 filaments. Here we report on the length-dependent expansion of 5 to 240
cm lengths of state-of-the-art, commercial Ag alloy-sheathed Bi-2212 wire after
full and some partial heat treatments. Detailed image analysis along the wire
length shows that the wire diameter increases with distance from the ends,
longer samples often showing evident damage and leaks provoked by the internal
gas pressure. Comparison of heat treatments carried out just below the melting
point and with the usual melt process makes it clear that melting is crucial to
developing high internal pressure. The decay of Jc away from the ends is
directly correlated to the local wire diameter increase, which decreases the
local Bi-2212 filament mass density and lowers Jc, often by well over 50%. It
is clear that control of the internal gas pressure is crucial to attaining the
full Jc of these very promising round wires and that the very variable
properties of Bi-2212 wires are due to the fact that this internal gas pressure
has so far not been well controlled
Comparasion between European elite senior and junior female table tennis players
The aim of the study was to compare elite junior and senior women table tennis players,
using three parameters of the table tennis: rally length, serve and receive analysis. Twentyfive junior and twenty-five elite senior matches were analysed (total: 263 sets and 4958
points) between players ranked in Top 25 in ETTU rankings in the last two years. All the
athletes used an offensive style of play. The results of non-parametric Mann-Whitney U Test,
showed a significantly higher rally length in senior compared to junior category (4.46 vs.
3.93). Moreover, the results of Pearson’s Chi-square tests show an association between the
age categories and selected parameters (laterality, technique and placement) for both serve
and receive. Different behavior between the two categories was noted. The senior players
used more the flip technique (22.2 % vs 14.7 %) and short push to return the services of the
opponents (32.5 % vs 26.0 %). These results provide useful information to analyze junior
players’ behavior compared to the senior players in order to plan specific training sessions.
It can be also useful to identify some parameters as predictors of the future success for
junior players
A Two-Fluid Thermally-Stable Cooling Flow Model
A new model for cooling flows in X-ray clusters, capable of naturally
explaining salient features observed, is proposed. The only requirement is that
a significant relativistic component, in the form of cosmic rays (CR), be
present in the intra-cluster medium and significantly frozen to the thermal
gas. Such an addition qualitatively alters the conventional isobaric thermal
instability criterion such that a fluid parcel becomes thermally stable when
its thermal pressure drops below a threshold fraction of its CR pressure.
Consequently, the lowest possible temperature at any radius is about one third
of the ambient temperature {\it at that radius}, exactly as observed, In
addition, we suggest that dissipation of internal gravity waves, excited by
radial oscillatory motions of inward drifting cooling clouds about their radial
equilibrium positions, may be responsible for heating up cooling gas. With the
ultimate energy source for powering the cooling X-ray luminosity and heating up
cooling gas being gravitational due to inward drifting cooling clouds as well
as the general inward flow, heating is spatially distributed and energetically
matched with cooling. One desirable property of this heating mechanism is that
heating energy is strongly centrally concentrated, providing the required
heating for emission-line nebulae.Comment: 13 pages, submitted to ApJ
Immune contribution to tentacle regeneration in adult mollusc and cnidarian models
Histological studies focusing on the early
cephalic tentacle regeneration in P. canaliculata,
have demonstrated that wound closure and
blastema formation took place within 24 h post
amputation (hpa). A Matlab® plugin allowed the
semi-automated identification and quantification of a
phagocytic hemocyte sub-population in the
blastema. Flow cytometry analysis showed that the
injection of the phagocyte-specific drug
Clophosome® (45 µg/g snail) could transiently
remove circulating hemocytes, that recovered the
pre-treatment level within 24 h. Consistently,
histological experiment demonstrated that rare
hemocytes were present in the early regenerating
tentacles of Clophosome®-injected snail
- …