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1.
Infection in insects stimulates a complex defensive response. Recognition of pathogens may be accomplished by plasma or hemocyte proteins that bind specifically to bacterial or fungal polysaccharides. Several morphologically distinct hemocyte cell types cooperate in the immune response. Hemocytes attach to invading organisms and then isolate them by phagocytosis, by trapping them in hemocyte aggregates called nodules, or by forming an organized multicellular capsule around large parasites. In the current investigation the cellular in the hemolymph third instar larvae of M. scutellaris has been characterized by means of light microscopy analysis and phagocytosis assays were performed in vivo by injection of 0.5 μm fluorescence beads in order to identify the hemocyte types involved in phagocytosis. Four morphotypes of circulating hemocytes were found in 3rd instar larvae: prohemocytes, plasmatocytes, granulocytes and oenocytoids. The results presented plasmatocytes and granulocytes involved in phagocytic response of foreign particles in 3rd instar larvae of M. scutellaris.  相似文献   

2.
Biomphalaria glabrata and Biomphalaria straminea have been identified as intermediate hosts for Schistosoma mansoni. Several studies have found two cell types in the hemolymph of B. glabrata (hyalinocytes and granulocytes). However, there are no studies describing the hemocytes of B. straminea. With the aim of further describing the hemocyte subsets in B. glabrata and B. straminea, we conducted a detailed study using optical microscopy and transmission electron microscopy. Based on the morphological characteristics of the cells, we identified the same types of hemocytes in two species of molluscs, namely: blast-like cells, granulocytes, type I hyalinocytes, type II hyalinocytes and type III hyalinocytes. Blast-like cells had a spherical profile with a central nucleus filling almost the whole cell. Granulocytes were characterized by presenting variable numbers of granules. Type I hyalinocytes were the most abundant cell type and displayed various cytoplasmic projections. Type II and type III hyalinocytes had never previously been reported. They were few in number and were characterized by having an eccentric nucleus. From these results, it is concluded that there are five types of cells in the hemolymph of B. glabrata and B. straminea. Further studies are now needed to identify the role of these hemocytes in the immune response of these snails.  相似文献   

3.
Membrane vesicles (MV) have been identified in seminal plasma from various species and they are thought to have a significant impact on semen quality and fertilisation. Although recently presence of MV has been also described in the canine ejaculate, detailed knowledge on their morphology is missing by now. This is, however, needed to provide a basis for detailed biochemical and functional studies as it is generally assumed that different MV populations are responsible for distinct tasks. MV were prepared for light (LM) and transmission electron microscopy (TEM) analysis using samples from normospermic dogs (n = 15), hypokinozoospermic dogs (n = 2, h) and one castrated azoospermic dog (a). For TEM, a new preparation protocol was used resulting in a higher MV retrieval rate. Using fractionated semen samples, most MV were identified in the second (sperm-rich) fraction in LM. Using pooled ejaculates, three different MV types could be identified in LM: (1) large MV with a marginal accumulation of opaque, granulated material, (2) medium- to small size MV with dense, opaque content and (3) small MV with no further defined contents. No direct contact between sperm and MV could be visualised. In TEM, 11 different MV types were identified based on diameter, structure, contents and electron density of contents as well as presence, number and size of smaller MV inside the MV itself. In normospermic males, secondary vesicles (type i, H, K1/2) included smaller vesicles and had a weighted mean diameter of 409.46 nm; hereof types i, H and K1 were smaller (mean: 287.55 nm, range: 51.25–994.86 nm) and type K2 was larger (mean: 1746.43 nm, range: 1003.66–3289.34 nm). Primary vesicles (mean diameter: 135.29 nm) – without vesicles inside – were differentiated into larger MV (A, B, C1/2) with a mean diameter of 219.63 nm (range: 39.08–1300.13 nm) and small primary MV (F, G) with a mean diameter of 66.12 nm (range: 24.62–99.84 nm). Whereas all mentioned MV were round to oval and mostly double-, rarely multiple-membrane surrounded, one longish primary MV type (L) was identified. In general, small primary vesicles were most common independent of semen quality, but distribution frequency of vesicle types differed between normospermic, pathospermic dogs and the castrated male. Mean weighted diameter of MV was 195.14 nm (range: 24.62–3289.34 nm) in normospermic males with the maximum diameter being smaller in the other dogs (h: 2096.78 nm; a: 1314.06 nm). Our results provide new information about ultrastructure and distribution frequency of canine MV in normospermic males and point to possible differences in MVs depending on semen quality. They provide the basis for further detailed functional analysis of MV subpopulations. Furthermore, the presence of MV in the castrated azoospermic male confirms an at least partly prostatic origin of canine MV.  相似文献   

4.
The freshwater crayfish Astacus leptodactylus (Eschscholtz, 1823) is an important aquacultured decapod species as well as an invasive species in some European countries. In the current investigation we characterized the different classes of circulating blood cells in A. leptodactylus by means of light and electron microscopy analysis and we explored their reaction to different latex beads particles in vivo by total and differential cell counts at 0.5, 1, 2 and 4h after injections. We identified hemocytes by granule size morphometry as hyaline hemocytes with no or rare tiny granules, small granule hemocytes, unimodal medium diameter granule hemocytes and both small and large granule containing hemocytes. The latter granular hemocytes showed the strongest phenoloxidase l-DOPA reactivity both in granules and cytoplasm. A. leptodactylus respond to foreign particles with strong cellular immune responses. All treatments elicited a total hemocyte increase with a conspicuous recruitment of large granule containing hemocytes. All hemocyte types mounted some phagocytic response but the small granule hemocytes were the only ones involved in phagocytic response to all foreign particles with the highest percentages. These results (1) depict the variability in decapod hemocyte functional morphology; (2) identify the small granule hemocyte as the major phagocytic cell; (3) suggest that the rather rapid recruitment of large granule hemocyte in all treatments plays a relevant role by this hemocyte type in defense against foreign particles, probably in nodule formation.  相似文献   

5.
Low level laser therapy (LLLT) is known for its positive results but studies on the biological and biomodulator characteristics of the effects produced in the skeletal muscle are still lacking. In this study the effects of two laser dosages, 5 or 10 J/cm2, on the lesioned tibial muscle were compared. Gerbils previously lesioned by 100 g load impact were divided into three groups: GI (n = 5) controls, lesion non-irradiated; GII (n = 5), lesion irradiated with 5 J/cm2 and GIII (n = 5), lesion irradiated with 10 J/cm2, and treated for 7 consecutive days with a laser He–Ne (λ = 633 nm). After intracardiac perfusion, the muscles were dissected and reduced to small fragments, post-fixed in 1% osmium tetroxide, dehydrated in increasing alcohol concentrations, treated with propylene oxide and embedded in Spurr resin at 60 °C. Ultrafine cuts examined on a transmission electron microscope (Jeol 1010) revealed in the control GI group a large number of altered muscle fibers with degenerating mitochondria, intercellular substance containing degenerating cell fragments and budding blood capillaries with underdeveloped endothelial cells. However, groups GII and GIII showed muscle fibers with few altered myofibrils, regularly contoured mitochondria, ample intermembrane spaces and dilated mitochondrial crests. The clean intercellular substance showed numerous collagen fibers and capillaries with multiple abluminal processes, intraluminal protrusions and several pinocytic vesicles in endothelial cells. It was concluded that laser dosages of 5 or 10 J/cm2 delivered by laser He–Ne (λ = 633 nm) during 7 consecutive days increase mitochondrial activity in muscular fibers, activate fibroblasts and macrophages and stimulate angiogenesis, thus suggesting effectivity of laser therapy under these experimental conditions.  相似文献   

6.
Leaf salt glands of Limoniastrum guyonianum were examined by scanning and transmission electron microscopes and energy dispersive X-ray analysis (EDAX) system, after growing for three months on sandy soil with or without 300 mM NaCl. Results showed that salt glands were irregularly scattered on both leaf sides and sunk under the epidermal level. Salt excretion occurred in both conditions and is mainly composed of calcium and magnesium in control plants, and essentially sodium and chloride in plants subjected to salt treatment. A salt gland is comprised of collecting, accumulating, and central compartments, and is made up of total thirty-two cells. The collecting cells were characterized by large central vacuoles. Accumulating cells contain numerous, large, and unshaped vacuoles and rudimentary chloroplasts. The central compartment was comprised of four basal cells and each one is surmounted by an apical cell. The basal cells are granulated, containing large nucleus, numerous mitochondria, endoplasmic reticulum, ribosomes, polyribosomes, and small vacuoles or vesicles. Equally, the apical cells are rich in organelles. Application of 300 mM NaCl to the culture medium increased vacuoles number and size, and organelles density especially the mitochondria which suggests energy requirement for ions transport. The reduction in size and number of vacuoles toward the interior of salt glands of treated plants and the fusion of the smallest ones with the plasma membrane substantiate the implication of such vacuoles in salt excretion process. The current study which is the first report on L. guyonianum salt gland has provided an in-depth understanding on structure–function relationship in the multicellular salt glands.  相似文献   

7.
Bombyx mori is a holometabolous insect found only in germplasm banks and morphological data related of resistance and susceptibility to diseases is important when selecting hybrids for commercial and scientific interest. This study analyzed the cytopathology of B. mori trachea to BmNPV, isolated geographically in Paraná state, Brazil. Fifth instar larvae were divided into two groups, control and inoculated; the viral suspension used was 2.4 × 107 polyhedral occlusion bodies/mL. From the second to the ninth day post-inoculation, segments of silkworm organs, containing the trachea, were processed for transmission electron microscopy. Analyses of fresh hemolymph were also performed to verify the susceptibility of the hemocytes. Signs of infection were initially detected in the hemocytes and in the tracheal cells on the second and fourth post-inoculation days, respectively. The cytopathology of the trachea showed all stages of the viral cycle, which was the same as in other tissues. Virions were detected in the basal lamina, which showed structural disorganization. So, the infection time of the hemocytes prior to trachea and the presence of virus in basal lamina, suggests that the trachea was a secondary target, infected by budded virus coming from the hemolymph.  相似文献   

8.
Iridaea cordata cultivated in the presence of UVB radiation (UVBR) was studied using transmission electron microscopy. Apical segments were cultivated in 0.97 Wm?2 of UVBR for 40 days, 3 h a day, and compared to a negative control (UVBR absent). UVBR caused modifications, mainly in the cortical cells, including an increased number of cell wall-producing vesicles, in addition to thicker and denser cellular walls, compared to the control. Additionally, cells were observed with an irregular contour and without defined organelles. The increase of cell-wall thickness could be interpreted as an acclimation to UVBR, which could lead to protection from this radiation.  相似文献   

9.
《Current Applied Physics》2010,10(2):407-410
The aluminum (Al) interlayer with various thicknesses ranging from 0.75 to 6 nm was deposited on silicon (Si) substrates prior to the deposition of ultra-thin iron (Fe) catalyst for the growth of carbon nanotubes. In this paper we report the effect of ultra-thin Al interlayer on the growth of multiwalled carbon nanotubes (MWCNTs). The SEM was used to examine the microstructures of nanotubes. We observed as the Al interlayer thickness increases the height of nanotube decreases. Raman spectra of MWCNT showed typical D and G peaks at ∼1345 cm−1 and ∼1575 cm−1, respectively. The XPS revealed the presence of Al and Fe on the top of CNT surface which were further supported by TEM. The high resolution TEM results also revealed bamboo like CNTs with diameter ∼10–40 nm.  相似文献   

10.
We report device linearity improvement and current enhancement in both a heterostructure FET (HFET) and a camel-gate FET (CAMFET) using InGaAs/GaAs high-low and GaAs high-medium-low doped channels, respectively. In an HFET, a low doped GaAs layer was employed to build an excellent Schottky contact. In a GaAs CAMFET, a low doped layer together withn+andp+layers formed a high-performance majority camel-diode gate. Both exhibit high effective potential barriers of >1.0 V and gate-to-drain breakdown voltages of >20.0 V (atIg=1.0 mA mm−1). A thin, high doped channel was used to enhance current drivability and to improve the transconductance linearity. A 2×100 μm2HFET had a peak transconductance of 230 mS mm−1and a current density greater than 800 mA mm−1. The device had a transconductance of more than 80 percent of the peak value over a wide drain current range of 200 to 800 mA mm−1. A 1.5×100 μm2CAMFET had a peak transconductance of 220 mS mm−1and a current density greater than 800 mA mm−1. Similarly, the device had a transconductance of more than 80 percent of the peak value over a wide drain current range of 160 to 800 mA mm−1. The improvement of device linearity and the enhancement of current density suggest that high-to-low doped-channel devices for both an HFET and a CAMFET are suitable for high-power large signal circuit applications.  相似文献   

11.
The effects of ultraviolet radiation-B (UVBR) in apical segments of the red macroalgae Gracilaria domingensis (Kützing) Sonder ex Dickie were examined in vitro. Over a period of 21 days, the segments were cultivated and exposed to photosynthetically active radiation (PAR) at 80 μmol photons m?2 s?1 and PAR + UVBR at 1.6 W m?2 for 3 h per day. The samples were processed for electron microscopy, as well as histochemical analysis, and growth rate, photosynthetic pigment contents and photosynthetic performance were measured. Toluidine Blue reaction showed metachromatic granulations in vacuole and lenticular thickness, while Coomassie Brilliant Blue showed a higher concentration of cytoplasmic organelles, and Periodic Acid Schiff stain showed an increase in the number of floridean starch grains. UVBR also caused changes in the ultrastructure of cortical and subcortical cells, which included an increased number of plastoglobuli, changes in mitochondrial organization, destruction of chloroplast internal organization, and the disappearance of phycobilisomes. The algae cultivated under PAR-only showed growth rates of 6.0% day?1, while algae exposed to PAR + UVBR grew only 2.8% day?1. Compared with algae cultivated with PAR-only, the contents of photosynthetic pigments, including chlorophyll a, phycoerythrin, phycocyanin and allophycocyanin, decreased after exposure to PAR + UVBR, and significant differences were observed. Finally, analysis of these four photosynthetic parameters also showed reduction after exposure to PAR + UVBR: maximum photosynthetic rate, photosynthetic efficiency, photoinhibition and relative electron transport rate. Taken together, these findings strongly suggested that UVBR negatively affects the agarophyte G. domingensis.  相似文献   

12.
The packing of chromatin during the self-assembly was modeled with a diamagnetic compression achieved under a gradient magnetic separation (magnetophoresis). Nucleoprotein granules separated from cultivated connective tissue and nuclei of chicken red blood cells formed various chromatin mesophases and chiral supra-molecular structures. The applied magnetic pressure accelerated mesophase formations due to the diamagnetic alignment and the concentrating of nucleosome nanoparticles and aggregates (germs) in gradient magnetic fields. Under various magnetic force parameters (H · grad H)  105–1011 Oe2/cm the different mesophases emerged. Chicken nucleated red blood cells were found to be a convenient model to study the chromatin condensation under influences including electromagnetic factors.  相似文献   

13.
An i-InGaP/n-InxGa1  xAs/i- GaAs step-graded doped-channel field-effect transistor (SGDCFET) has been fabricated and studied. Due to the existence of a V-shaped energy band formed by the step-graded structure, a large output current density, a large gate voltage swing with high average transconductance, and a high breakdown voltage can be expected. In this study, first, a theoretical model and a transfer matrix technique are employed to analyze the energy states and wavefunctions in the step-graded quantum wells. Experimentally, for a 1  ×  80 μm2gate dimension device, a maximum drain saturation current density of 830 mAmm  1, a maximum transconductance of 188mSmm  1 , a high gate breakdown voltage of 34 V, and a large gate voltage swing 3.3 V with transconductance larger than 150 mSmm  1are achieved. These performances show that the device studied has a good potentiality for high-speed, high-power, and large input signal circuit applications.  相似文献   

14.
Single-domain nanoscale magnetic iron particles have been embedded uniformly in an amorphous matrix of alumina using a pulsed laser deposition technique. Structural characterization by transmission electron microscopy (TEM) reveals the presence of a crystalline iron and an amorphous alumina phase. Fine particle magnetism have been investigated by carrying out field and temperature dependence of magnetization measurements using superconducting quantum interference device magnetometer. The particle size of Fe in Al2O3 matrices prepared by changing the deposition time of Fe, have been found to be 9, 7 and 5 nm from TEM studies. At 10 K, the coercivities of these samples are found be 450, 350 and 150 Oe, respectively. At 300 K, the coercivity of Fe–Al2O3 sample decreases from 100 to 50 Oe as the particle size decreases from 9 to 7 nm and finally the sample turns superparamagnetic when the Fe particle size becomes around 5 nm. Based on the calculated value of blocking temperature, TB, (481 K), magnetic anisotropy K (4.8×105 erg/cm3) for Fe, and the Boltzmann constant kB (1.38×10−16 erg/K) from TB=KV/25kB, the mean radius of Fe particles is found to be 9.3 nm. in one of the samples. This is in good agreement with the particle size measured using TEM studies.  相似文献   

15.
The hot band 3ν9?ν9 of the isotopologue 11BF2OH (difluoroboric acid) located at 1034.78 cm?1 was investigated for the first time by Fourier transform infrared spectroscopy. During previous studies both, the ν9 mode (OH-torsion relative to the BF2 moiety, at 522.87 cm?1) and the ν4 mode (in-plane OH bend) had been shown to exert large amplitude motion, and splittings of 0.0051 and 0.0038 cm?1 had been observed in the interacting 2ν9 and ν4 bands located at 1042.87 and 961.49 cm?1, respectively. The present work establishes large amplitude effects also for the 93 excited state located at 1557.655 cm?1. Numerous P and R transitions of the 3ν9ν9 hot band were identified in the 2ν9 manifold, and doublets corresponding to a torsional splitting of 0.031 cm?1 in the 93 state were observed. The vibrational assignment of the 93 state was confirmed by the detection of the 3ν9?2ν9 hot band Q branch in the 19 μm region.  相似文献   

16.
Kunio Wakamura 《Solid State Ionics》2009,180(26-27):1343-1349
We find the relationships among optical dielectric constant ε, activation energy Eac, averaged atomic mass per a formula unit, ∑jmj / N, volume V and transition temperature Tc for various type ion conductors with forms of Eac = α / (ε ? β), Eac = A0 + δ / [(∑jmj / N) ? d], Eac = Av / V2/3, and ln(Tc) = g ? hln(∑jmj), where α, β, δ, A0, d, Av, g and h are constants depending on the kinds of conduction elements. We derive those proportional forms from a simple equation of motion under the assumption of ion hopping assisted by enhanced vibration displacement of host lattice. The enhancement is induced from the large fourth-order term of the host lattice potential originating from the electronic shielding effect of Coulomb force, heavy atomic mass of constituent ion, and volume expansion under the long-range periodicity of crystal structure. This mechanism is ascertained from characteristic phenomena of various kinds of conduction elements. For impurity-type H+-ion or defect conductor, the proportional form is shifted from that of superionic conductor because of weakened effect of host lattice vibration mode on H+-ion or O-ion defect. Photo-induced spectra of mobile ion in AgCl are understood, and a small quantum effect of H+ -ion is suggested.  相似文献   

17.
Correlation of phase formation, critical transition temperature Tc, microstructure, and critical current density Jc with sintering temperature has been studied for acetone doped MgB2/Fe tapes. Sintering was performed at 600–850 °C for 1 h in a flowing Ar atmosphere. High boron substitution by carbon was obtained with increasing the sintering temperature; however, the acetone doped samples synthesized at 800 °C contain large size MgB2 grains and more MgO impurities. Incomplete reaction for the acetone doped samples heated at 600 °C result in bad intergrain connectivity. At 4.2 K, the best Jc value was achieved in the acetone doped sample sintered at 700 °C, which reached 24,000 A/cm2 at 10 T and 10,000 A/cm2 at 12 T, respectively. Our results indicate that the small grain size and less impurity were also important for the improvement of JcB properties besides the substitutions of B by C.  相似文献   

18.
Amorphous Si/SiO2(a-Si/SiO2) superlattices have been fabricated by the magnetron sputtering technique. The superlattice with an Si layer thickness of 1.8 nm has been characterized by transmission electron microscopy (TEM). The result indicates that most of the regions in the Si layer consist of amorphous phase, while regular structure appears in some local regions. This is in agreement with the Raman scattering spectroscopy. The optical absorption spectrum and photoluminescence (PL) spectrum have been measured. Moreover, the third-order optical nonlinearity χ(3)of this superlattice has been measured. To our knowledge, this is the first investigation of the nonlinear absorption and refractive index of an a-Si/SiO2superlattice using the Z -scan technique. The real and imaginary parts of χ(3)have been found to be 1.316  ×  10  7eus and   5.596  ×  10  7eus, respectively, which are about two orders of magnitude greater than those of porous silicon. The results may be attractive for potential application in electro-optics devices.  相似文献   

19.
We studied the effect of TiO2 doping on flux pinning and superconducting properties of a melt-grown (Nd0.33Eu0.33Gd0.33) Ba2Cu3Oy + 35 mol% Gd2BaCuO5 (70 nm in size) composite (NEG-123) processed in Ar–1% O2 atmosphere. As indicated by similar, sharp superconducting transitions, the small quantities of TiO2 used in our experiments did not deteriorate superconducting properties of the NEG material. Transmission electron microscopy (TEM) analysis found 20–50 nm Ti-based particles in the NEG-123 matrix. However, we have not observed the clouds of <10 nm sized particles in the NEG-123 matrix, as in the case of recently reported NEG-123 composites doped by Mo and Nb nanoparticles. Nevertheless, quite a good JcB performance in the 0.1 mol% Ti-doped sample, namely 550 kA/cm2 at the self-field and at the secondary peak field (4.5 T) was achieved at 65 K, while 320 kA/cm2 was obtained at zero-field at 77 K, and 50 kA/cm2 at 90.2 K. The pinning effectiveness decreased with increasing Ti content above 0.2 mol%. The analysis of the pinning force showed that higher concentration of Ti (>0.2 mol%) increased the amount of normal pins (δl pinning), indicated by the Fp(h) peak shift from h = 0.42–0.36. The maximum pinning effect in a broad field range could be achieved by optimizing Ti content and adding sub-micron Gd-211 particles.  相似文献   

20.
This paper reports the visible luminescence properties of 1D2 state of Tm3 + -doped lead borate titanate aluminumfluoride (LBTAFTm) glasses. The absorption and luminescence was analyzed within the frame work of Judd-Ofelt model. The reliability of J-O intensity parameters obtained from the experimental oscillator strengths have satisfactorily been correlated with the calculated oscillator strengths with small r.m.s deviation of ± 0.12 × 10-6 by the least square fit analysis. Upon 359 nm excitation, the luminescence spectra show only one emission band at 458 nm (blue) corresponding to the 1D2  3 F4 transition in the spectral region 400–500 nm. No luminescence quenching has been observed with the increase of Tm3 + concentration. The decay profiles of the 1D2 level have shown single-exponential nature for all the concentrations and the decay times were found to decrease with the increase of concentration. The stimulated emission cross-section (σe) for the observed emission transition has also been computed. The large quantum efficiency (η) of the 1D2 level suggests the utility of LBTAFTm glass as a potential host for optical device applications at 458 nm emission wavelength.  相似文献   

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