Microanatomy and ultrastructure of outer mantle epidermis of the cuttlefish,Sepia esculenta (Cephalopoda: Sepiidae)

This study describes the ultrastructural characteristics of external epidermis of mantle of Sepia esculenta using light and electron microscopy. The epidermis was thicker on the ventral surface than on the dorsal surface, with a higher secretory cell distribution on the ventral surface than on the dorsal surface. The epidermis was a single layer composed of epithelial cells, secretory cells, ciliated cells and neuroglial cells. Epithelial cells were columnar with well-developed microvilli on the free surface, and the microvilli were covered with glycocalyx. The epithelial cells were connected to the neighboring cells by tight junctions and membrane interdigitations of the apico-frontal surface. Well-developed microfilaments were arranged in a vertical direction in the cortical cytoplasm. The secretory cells were categorized into three types (A, B and C) in accordance with the light microscopical characteristics and ultrastructures of the secretory granules. The distribution of these cells was in the following order: Type A > Type B > Type C. SEM observation revealed that the secretory pore size of the Type A secretory cells was approximately 8.6 μm × 12.2 μm. Cytoplasm displayed a red color as the result of Masson's trichrome stain and H–E stain, and contained polygonal granules of approximately 1.2 μm² with a high electron density. The secretory pore size of the Type B secretory cells was approximately 10.1 μm × 12.1 μm. As the results of AB–PAS (pH 2.5) and AF–AB (pH 2.5) reactions, the cytoplasm displayed a red color. The cells contained membrane bounded secretory granules with very low electron density. The secretory pore of the Type C secretory cells was circular shape, and approximately 5.5 μm × 5.5 μm. Cytoplasm was found to be homogeneous under H–E stain and Masson's trichrome stain, and displayed a red color. As the result of AB–PAS (pH 2.5) reaction, the cytoplasm displayed a red color. The electron density of the secretory substance was the highest among the three types of secretory cells. The ciliated cells had a ciliary tuft on the free surface and were distributed throughout the mantle with the exception of the adhesive organs. Neuroglial cells were connected to the basal membrane, epithelial cells, secretory cells and nerve fibers through cytoplasmic process, and contained neurosecretory granules with high electron density within the cytoplasm.     

Ultrastructure of the seminal vesicle and sperm storage in Panorpidae (Insecta: Mecoptera)

The histology and ultrastructure of the seminal vesicle, male accessory gland and the epididymis in Panorpa and Sinopanorpa were observed using light microscopy and scanning and transmission electron microscopy. The seminal vesicle consists of a mono-layered elongated columnar epithelium, which contains abundant electron-dense granules and secretory vesicles, and a small central lumen. In the apical region of the epithelium of the seminal vesicle, the intense secretory activity seems to be effected by means of merocrine mechanisms. The epithelium of the accessory gland is rich in rough endoplasmic reticulum and Golgi complex, and secretes seminal fluid into the lumen via both apocrine and merocrine mechanisms. The seminal vesicle is similar to the accessory gland in the epithelium structure and their secretory activity, mainly serving a secretory function rather than storing sperms. Instead, the sperms are stored in the epididymis, whose epithelium secretes nutrients into the large lumen by merocrine mechanisms. The secretory activity and function of the seminal vesicle are briefly discussed.     

Spatially-resolved thermoluminescence from snail opercula using an EMCCD

In recent years opercula of the snail species Bithynia tentaculata have been shown to emit thermoluminescence (TL) signals that can be used to determine equivalent dose, and may be capable of dating events throughout the entire Quaternary period. Concentric growth lines are a notable feature of almost all B. tentaculata opercula, but it is not known whether the luminescence emitted by the opercula is influenced by these structures. This study uses a newly developed EMCCD imaging system to measure the TL signals from opercula. A combination of microscopic analysis of the opercula using visible imagery, and measurement of the TL using the EMCCD system has been undertaken. Variations in TL intensity and equivalent dose (D_e) are seen, but the two are not correlated. Changes in TL intensity broadly mimic the concentric growth structures, but the largest variations in intensity are between different margins of the opercula, not individual growth bands. The EMCCD system makes it possible to produce a two dimensional map of the D_e measured from an operculum. Dose recovery experiments give D_e values that are consistent with each other across the whole opercula. Measurement of the D_e arising from irradiation in nature shows significant variability across a single operculum, but at present the reason for this variability is unknown.     

Male reproductive system structure and accessory glands ultrastructure of two species of Triatoma (Hemiptera,Reduviidae, Triatominae)

Morphological studies in male reproductive system of insect, and accessory glands functions, can contribute to the knowledge of reproductive aspects in Triatominae. The present study aims to describe the structure of male reproductive system under scanning electron microscopy, and the ultrastructure of accessory glands during the process of maturation, in T. brasiliensis and T. melanica of different ages.These system consist of two testis, two vas deferens, two seminal vesicles, four pair of accessory glands and one ejaculatory duct. The four mesodermal male accessory glands of T. melanica and T. brasiliensis, present secretion storage in the firsts days of adult life in starved males. During the maturation process of male accessory glands of T. brasiliensis and T. melanica, granules with different sizes, shapes and electron density were seen. In T. melanica small vacuoles are released into the gland lumen in one-day-old males, however, after three and five days few granules are found in the cell cytoplasm. The secretory granules in T. brasiliensis increase in size and amount, in the five days old adult. The secretory pathway in the male accessory glands of the two species seems to be merocrine and apocrine suggesting that different substances are being produced at different times. The cell microvilli in T. brasiliensis are longer and narrower, these can be absent in some regions of the cell surface of T. melanica. Maturation of male accessory glands in the triatomine species studied occurred without adult blood meal. Its function can led to new insights for the comprehension of reproductive aspects in Triatominae.     

Ultrastructural observation on genesis and morphology of cortical granules in Macrobrachium nipponense (Crustacea,Caridea)

Cortical granules are secretory vesicles in oocytes that develop from the Golgi complex. In the freshwater shrimp, Macrobrachium nipponense, mitochondria participates in the formation of cortical granules. We investigated the structural changes of mitochondria and the distribution cortical granules in different stages of oocyte development. Transmission electron microscopy provided evidence for the involvement of mitochondria and a particular spiral lamellar organization and an electron-lucent area in internal cortical granules. The ooplasm provided material for the cortical granules in early oocyte development. We demonstrated that mitochondria play a role in coalescence and maturation of cortical granules in this species. Additionally, a concept of cortical granules regarded as a functional integration is put forward. The genesis of shrimp cortical granules exhibited a particular pathway of maturation. The outer shape and inner organization considering different taxa suggested general as well as specific features of the development of cortical granules.     

On the theory of thermodiffusiophoresis of a moderately coarse two-layer volatile aerosol particle

A hydrodynamic method with slip is used to construct a theory of uniform thermodiffusiophoretic transfer of a volatile high-viscosity two-layer particle under conditions in which one component of a moderately rarefied binary gas mixture undergoes phase transition on the particle’s surface. The solid spherical core and high-viscosity sheath of the particle are concentric to each other. The theory suggests that, when moving, a two-layer volatile aerosol particle may be considered as a homogeneous particle with an effective thermal conductivity. The effect of the evaporation rate, interfacial temperature steps, and presence of the core on the rate of thermodiffusiophoresis is considered. Thermal diffusion terms, Stefan effects, and the heat evolution due to the convective transfer of the evaporating mass are taken into account. Under the same initial assumptions, formulas derived in this work are of wider practical significance than those following from the conventional approaches.     

Morphology and ultrastructure of the venom apparatus in the endoparasitic wasp Pteromalus puparum (Hymenoptera: Pteromalidae)

The venom apparatus of the endoparasitic wasp Pteromalus puparum (Hymenoptera: Pteromalidae) was studied with light and electron microscope and was subjected to the electrophoretic and immunohistochemical analyses. Typically its venom apparatus consists of an unbranched venom gland and a venom reservoir, which is associated with a Dufour gland. The venom gland is lined by a series of secretory units. Each secretory unit comprises a secretory cell and a duct cell. The secretory cell is associated with an end apparatus to collect its secretions into the gland lumen. Secretory cells in the venom gland are characterized by extensive rough endoplasmic reticulum and numerous electron-dense vesicles in the distal and middle parts. They also exhibit several secretory granules and vacuoles. The venom reservoir presents three distinct regions: an external layer, composed by numerous fine muscle fibers; an internal layer, represented by epithelial cell with large nucleus; and an intima portion, represented by thin and uniform organization. The morphological aspect of numerous well-developed organelles responsible for protein generation observed is in agreement with the electrophoretic and immunohistochemical results which reveal that the rich proteinaceous components are present in the venom gland and venom reservoir. The venom proteins are first mainly produced in the secretory unit of venom gland, then drained to the lumen through the end apparatus, and are finally collected and stored in the venom reservoir.     

Unipolar model of negative corona discharge: Comparison of calculated and experimental <Emphasis Type="Italic">I–V</Emphasis> characteristics for the sphere–plane electrode system

Substantial computational resources and time are needed for computer simulation of the corona discharge with allowance for the sheath processes. This circumstance necessitates a search for and development of simplified models in which the processes in the sheath of corona discharge are reduced to the boundary condition at the surface of active electrode. A unipolar model that takes into account only one type of carriers is considered, and the boundary condition on the discharge electrode describes the rate of variations in the electron-flux density from the sheath. The calculated I–V characteristics are compared with experimental data for interelectrode distances ranging from several millimeters to several centimeters to reveal the applicability of the model. The simulated and experimental results are in good agreement at interelectrode distances of greater than 1 cm.     

Femtosecond laser-induced concentric ring microstructures on Zr-based metallic glass

Surface morphological evolution of Zr-based metallic glass ablated by femtosecond lasers is investigated in atmosphere condition. Three types of permanent ring structures with micro-level spacing are observed for different laser shots and fluences. In the case of low laser fluences, the generation of annular patterns with nonthermal features is observed on the rippled structure with the subwavelength scale, and the ring spacing shows a decrease tendency from the center to the margin. While in the case of high laser fluences, the concentric rings formation within the laser spot is found to have evident molten traces and display the increasing ring spacing along the radial direction. Moreover, when the laser shots accumulation becomes large, the above two types of ring microstructures begin to develop into the common ablation craters. Analysis and discussion suggests that the stress-induced condensation of ablation vapors and the frozen thermocapillary waves on the molten surfaces should be responsible for the formation of two different types of concentric ring structures, respectively. Eventually, a processing window for each resulting surface microstructure type is obtained experimentally and indicates the possibility to control the morphological transitions among different types.     

Ultrastructural properties of the Theromyzon (Annelida: Hirudinae) cocoon membrane

The cocoon of the leech Theromyzon trizonare consists of fibrils packed into an arrangement that produces both C- and S-like patterns of bow-shaped lines in sections oblique through the membrane. Sections normal to the cocoon membrane show layers containing cross-sections of fibrils (approximately 16 nm dia.) that are separated by a center-to-center distance of approximately 23 nm. In cross-section, each fibril presents a central hole approximately 5 nm in diameter. A structureless layer covers most of the exterior surface of the cocoon membrane, and short protuberances are apparent in some zones.     

Topochemistry,optical anisotropy and FT-IR microspectroscopy of the cocoon of Lithurgus chrysurus (Hymenoptera,Megachilidae)

A previous study has not revealed the participation of a mucous component in the cocoon wall of the solitary bee, Lithurgus chrysurus, differing from the cocoon structure reported for many other bee species. However, uncertainty remains, because only the median and rear zones of this cocoon type have thus far been analyzed. Here, we studied the front zone of this cocoon, searching its components and their organization, to fill this knowledge gap. Topochemical assays, polarization microscopy and Fourier transform-infrared (FT-IR) microspectroscopy were used to study cross sections from L. chrysurus cocoon. Three main layers differing in structural organization were found to compose the cocoon wall. Silk fibroins were assumed to constitute the filamentous threads of the inner and outer layers and the laminar structure of the intermediate layer. Deduced from its topochemical properties and FT-IR spectral signature, a foamy material containing mucin glycoproteins and carboxylated acid glycosaminoglycans was found in the intermediate layer. FT-IR analysis using a Savitzky-Golay 2nd-derivative and absence of linear dichroism and birefringence phenomena suggest that a random-coil secondary structure predominates in the foam component. Co-existence of α-helical and β-sheet conformations is also hypothesized for the fibroin component of this cocoon. It is thus concluded that in addition to fibroin elements, a mucous component, likely contributed by a Malpighian tubule secretion, integrates the composition of the front zone of the cocoon wall of L. chrysurus. In addition, the FT-IR analysis of the inner layer silk of this cocoon suggests significant differences in comparison to the silk fibroins of the silkworm, and some minor spectral differences in comparison to published data on the honeybee silk, with respect to protein secondary structure.     

Modal focusing effect of positive and negative ions by a three-dimensional plasma-sheath lens

A complex focusing effect of positive and negative ions caused by the sheath forming to biased electrodes that interface insulators has been found by solving in three dimensions the potential distribution and ion kinetics within the sheath. Thus, intrinsically correlated with the sheath shape, certain electrical charges are focused on the surface, forming well defined patterns named modal lines and modal spots. Their superposition to the previously reported discrete focusing leads to a total flux that represents a "fingerprint" of the entire sheath on the electrode surface. The ion flux pattern is developed experimentally on the surface of square and octagonal electrodes exposed to Ar/SF(6) and CF4 plasmas. Present results are of high potential importance for fundamental studies concerning sheath formation and charge kinetics and also in a wide range of plasma applications.     

Ion emission from a hollow-cathode discharge with the plasma penetrating into the high-voltage acceleration gap

The general features of ion emission from a gas-discharge plasma are considered under conditions such that the plasma penetrates into the acceleration gap. It is found that the wall sheath limiting the open plasma surface substantially affects the stability of the penetrating plasma. It is shown that there are two plasma states with different positions of the plasma boundary. The stable state corresponds to the inequality r/R > 0.54, where r is the plasma radius in the accelerating electrode and R is the radius of the aperture of the accelerating electrode. It is shown that the plasma-sheath system within the aperture of the accelerating electrode can exist only if the voltage drop across the sheath does not exceed a certain limiting voltage, which depends on the plasma parameters.     

Effects of the Chodura sheath on tungsten ionization and emission in tokamak divertors

The decay of the electric potential in the sheath region in tokamak divertors occurs on a scale length on the order of the main ion gyroradius (Chodura sheath) due to magnetic fields lines intersecting the divertor plates at grazing incidence. As a consequence, high-Z impurities like tungsten ionize within the sheath region in attached plasma conditions. The modification of the electron distribution in the sheath region must thus be taken into account to accurately model ionization and emission of impurities within the sheath region. To that end, an analytical expression of the distribution of the vertical ionization path for impurities sputtered from divertor plasma-facing components is derived. This expression is then used to estimate the fraction of neutral impurities ionizing within the sheath and the average vertical ionization path, and to derive an effective SXB (the number of ionizations per emitted photon) coefficient which includes the effects of the variation of the electron distribution in the sheath region. These results are applied to tungsten impurities sputtered from divertor plates. It is shown that the SXB coefficient for neutral tungsten is significantly reduced in high-density attached divertor plasma conditions (n_e ≳ 5 × 10¹³ cm⁻³) because of the ionization of neutral tungsten well within the sheath region.     

Role of nonlocal ionization in formation of the short glow discharge

An analytical model for estimating basic characteristics of short (without a positive column) glow discharges is suggested that allows for electron generation both in the cathode sheath and by nonlocal ionization in the plasma negative glow. The model is based on a previously developed approach according to which the discharge gap is divided into space-charge layers and a quasi-neutral plasma. The plasma region includes part of the negative glow, Faraday dark space, and positive column (if it exists). Simple expressions for basic characteristics of the glow discharge (I–V characteristic, cathode sheath thickness, position of the point of electric field reversal, etc.) are derived, and plasma concentration distributions are presented. The results obtained in terms of our model are in good agreement with experimental data, while local approximations based on the classical Engel-Steenbeck model diverge considerably from the experiment.     

Microfluidic colloidal island formation and erasure induced by surface acoustic wave radiation

Spatiotemporal patterns form in many nonlinear physicochemical or biological systems. Although unusual, microfluidic systems are no exception. We observe such patterns to form by colloids along the free surface of a drop beneath which surface acoustic waves propagate, and propose fundamental mechanisms to elucidate their formation. With increasing excitation amplitude, the colloids first assemble into concentric rings and then cluster into islands due to a combination of capillarity and surface acceleration. As the excitation is further increased, fluid streaming commences within the drop, inducing a transient metastable state in which the system alternates between colloidal island formation on the quiescent drop surface and subsequent erasure due to local vortex generation.     

Comparison between measured and calculatedRF losses in the superconducting state

Results of experiments and of the BCS-theory on the surface resistance of superconductors are presented. It will be shown that agreement between theory and experiment can be achieved by using revised material parameters. In the case of lead and niobium we will show that therf absorption decreases markedly with decreasing mean free pathl. This dependence on mean free path can become a method to measurel in a surface sheath.     

Concentric piecewise azimuthally polarized beam by a pure phase plate

Focusing properties of the azimuthally polarized beam induced by a pure phase plate are investigated theoretically. The pure phase plate consists of two concentric portions, one center circle portion and one outer annular portion, through which the azimuthally polarized beam passed evolves into concentric piecewise azimuthally polarized beam. When the phase shift of the center portion is π, one ring focus may evolve into novel focal patterns with increasing radius of the center circle portion, such as cylindrical crust focus, two-ring focus, and three-ring focus. And if the geometrical parameters are unchanged, focal patterns also changes considerably with tunable phase of the center portion. Ring focus shifts along the optical axis on the increasing phase. Some optical gradient force distributions and dependence of focal shift on phase shift are also illustrated. This kind of concentric piecewise azimuthally polarized beam can be used in optical manipulation technology.     

Determination of thickness and optical constants of metal films from an extended ATR spectrum by using a statistical method

Sudden changes in reflectivity within a small angle or wavelength range are very sensitive to both the metal film thickness and optical constants. Metal films such as silver or gold display two sudden changes in their reflectance curve ? the first occurring at the critical angle, which is then followed by a sharp surface plasmon resonance (SPR) dip at an incident angle that is a few degrees greater than the critical angle. In this report, we describe a method involving the optimization of the sum of squared difference (SSQ) to produce good fitting amongst the reflectivity data points from a function curve derived from theory. The standard errors on each output parameter for the best curve fit are determined from the covariant matrix eigenvalues.     

Acute and subchronic exposure of diplopods to substrate containing sewage mud: Tissular responses of the midgut

Several discussions regarding the agricultural use of sewage mud have occurred; however, its use has been questioned due to the risks of soil contamination mainly by metals. Diplopods are saprophagous invertebrates, agile in colonizing several layers of soil. Due to the habit of this group, several researchers have proposed their use in ecotoxicological analyses. This study aimed to expose these invertebrates to substrate containing sewage mud of a STS (Sewage Treatment Station) from São Paulo State, Brazil and analyzed its toxic potential by morphological analysis of the midgut of the diplopod Rhinocricus padbergi, region of the digestive tube where digestion and nutrient absorption occur. The animals were exposed in mud concentrations at 1%, 10% and 50% mixed with soil from the collection site for periods of 7 (acute exposure), 15 (intermediary exposure) and 90 (subchronic exposure) days in each treatment. The animals from the control group did not present alterations at all the exposition times. As an acute response (7 days), it was observed in the animals exposed to mud at 1% and 10% an increase in the epithelial renovation and in the liberation of secretory vesicles of glycoprotein content. In the animals exposed to mud at 50%, the main alteration observed was the increase in the number of cytoplasmatic granules in the fat body cells; the epithelium seemed to be in reorganization process in all the observed individuals, suggesting an intense epithelial renovation. In the intermediary period of exposure (15 days), in the animals exposed to mud at 1% it was observed an increase in the number of haemocytes among the cells of the fat body, distributed both separately and grouped; the animals exposed to mud at 10% presented the same evidence of epithelial renovation observed in the animals exposed for 7 days at a concentration of 50% of mud; it was also observed an increase in the number of haemocytes, which reacted strongly to the PAS technique. Cytoplasmatic granules in the hepatic cells, fat body cells and haemocytes were also observed in great number, being that great part presented calcium in their constitution. In the animals exposed to mud at 50%, the alteration observed was the presence of numerous secretory vesicles of the apocrine type through all the epithelia of vacuolated aspect; hepatic cells with cytoplasmatic granules were also observed. As subchronic response (90 days), it was observed that all the fat body cells were completely taken by cytoplasmatic granules, into which it was, detected the presence of calcium; such granules were also observed in the apical region of the principal epithelial cells. These results suggest the existence of toxic agents in the analyzed mud sample, whose different concentrations trigger responses that occur in different manners, intensities and velocities that might prevent the entrance and action of toxic agents in the organism of the studied invertebrate.