Propagation speed of sound assessment in the layers of the guinea-pig esophagus in vitro by means of acoustic microscopy.

The study's purpose was to evaluate the propagation speed of sound in the tissue layers of the esophagus at various mechanical loadings. Scanning laser acoustics microscopy was applied for the estimation of the propagation speed in the mucosa-submucosa and muscle layers of guinea-pig esophagus in vitro (n = 26). The propagation speed in the esophagus was determined in the no-load state with all external forces removed, and in the distended and zero-stress states. The zero-stress state was obtained by cutting the esophageal rings radially. The propagation speed in the no-load state differed significantly (p < 0.001) between the muscle layer (median 1740, quartiles 1735-1746 m/s) and the mucosa (1607, 1605-1609 m/s). In the distended state the propagation speed in the muscle layer decreased significantly (p < 0.001) to 1673 (1666-1681) m/s while it did not change significantly in mucosa (1602, 1600-1607 m/s). When compared to the no-load state, the propagation speed in the zero-stress state in the muscle layers decreased to 1624 (1615-1636) m/s (p < 0.001) and in mucosa to 1584 (1566-1603) m/s (p < 0.001). In conclusion, the esophagus is a composite structure with heterogeneous propagation speed characteristics. Furthermore, the mechanical loading state must be considered in esophageal ultrasound studies.     

Pulvinus functional traits in relation to leaf movements: a light and transmission electron microscopy study of the vascular system

Previous studies on legume pulvini suggest that the vascular system plays an important role in the redistribution of ions and transmission of stimuli during leaf's movements. However, the number of anatomical and ultrastructural studies is limited to few species. The aim of this paper is to investigate the structure and cellular features of the pulvinus vascular system of nine legume species from Brazilian cerrado, looking for structural traits pointing to its participation in the leaf's movements. Samples were excised from the medial region of opened pulvinus of Bauhinia rufa, Copaifera langsdorffii, Senna rugosa (Caesalpinioideae), Andira humilis, Dalbergia miscolobium, Zornia diphylla (Faboideae), Mimosa rixosa, Mimosa flexuosa and Stryphnodendron polyphyllum (Mimosoideae), and were prepared following light microscopy, transmission electron microscopy and histochemical standard techniques. The vascular system occupies a central position, comprises phloem and xylem and is delimited by a living sheath of septate fibers in all the species studied. This living cells sheath connects the cortex to the vascular tissues via numerous plasmodesmata. The absence of fibers and sclereids, the presence of phenolic idioblasts and the abundance and diversity of protein inclusions in the sieve tube members are remarkable features of the phloem. Pitted vessel elements, parenchyma cells with abundant cytoplasm and living fibriform elements characterize the xylem. The lack of lignified tissues and extensive symplastic continuity by plasmodesmata are remarkable features of the vascular system of pulvini of the all studied species.     

Heat treatment of human esophageal tissues: Effect on esophageal cancer detection using oxygenated hemoglobin diffuse reflectance ratio

The main objective of the present work is to study the influence of heat treatment on the esophageal cancer detection using the diffuse reflectance (DR) spectral intensity ratio R540/R575 of oxygenated hemoglobin (HbO₂) absorption bands to distinguish the epithelial tissues of normal human esophagus and moderately differentiated esophageal squamous cell carcinoma (ESCC) at different heat treatment temperature of 20, 37, 42, 50, and 60°C, respectively. The DR spectra for the epithelial tissues of the normal esophagus and ESCC in vitro at different heat-treatment temperature in the wavelength range 400–650 nm were measured with a commercial optical fiber spectrometer. The results indicate that the average DR spectral intensity overall enhancement with concomitant increase of heat-treatment temperature for the epithelial tissues of normal esophagus and ESCC, but the average DR spectral intensity for the normal esophageal epithelial tissues is relatively higher than that for ESCC epithelial tissues at the same heat-treatment temperature. The mean R540/R575 ratios of ESCC epithelial tissues were always lower than that of normal esophageal epithelial tissues at the same temperature, and the mean R540/R575 ratios of the epithelial tissues of the normal esophagus and ESCC were decreasing with the increase of different heat-treatment temperatures. The differences in the mean R540/R575 ratios between the epithelial tissues of normal esophagus and ESCC were 13.33, 13.59, 11.76, and 11.11% at different heat-treatment temperature of 20, 37, 42, and 50°C, respectively. These results also indicate that the DR intensity ratio R540/R575 of the hemoglobin bands is a useful tool for discrimination between the epithelial tissues of normal esophagus and ESCC in the temperature range from room temperature to 50°C, but it was non-effective at 60°C or over 60°C.     

Leaf emergences in Microlepis oleaefolia (DC.) Triana (Melastomataceae) and their probable function: an anatomical and ultrastructural study

Microlepis oleaefolia (DC.) Triana, an endemic species of Melastomataceae from the Brazilian cerrado, presents very complex leaf structures called as "hairs with root-like base" embedded in the mesophyll. This paper describes the ontogenesis, histochemical and structural aspects of these leaf structures as a framework for further functional studies. Samples of leaves in different developmental stages were processed according to common light and electron microscopy techniques. Fresh material was subjected to histochemical tests to examine the chemical composition of cell walls. The apoplastic transport between leaf emergences and the vascular system was verified by staining with 1% aqueous safranin. The structures are emergences of mixed protoderm and ground meristem origin. They are persistent, predominantly short-stalked and dendritic. Their arms have thick non-lignified cellulosic walls with a loose and heterogeneous aspect; on the inner face, the wall, which appears labyrinthine, presents small irregularly shaped projections directed towards the protoplast. The base of the emergences is composed of sclereids embedded in the mesophyll that reach the vascular system. Assays with aqueous safranin solution revealed it penetrates the cell walls of the arms and showed a connection between the emergence and xylem. Anatomical, chemical and ultrastructural features of leaf emergences of M. oleaefolia indicate that these structures are able to transport substances via apoplast and can absorb or exude solutions.     

Morphostructural analysis of the male reproductive system and DNA barcoding in Balclutha brevis Lindberg 1954 (Homoptera,Cicadellidae)

Balclutha brevis Lindberg 1954 is an allochthonous leafhopper infesting an invasive grass, Pennisetum setaceum, in Sicily and in mainland Europe; therefore, this species could compete with populations of native species, thus contributing to the loss of biodiversity. Considering the ecological implications of B. brevis, investigations on all its biological aspects represent, therefore, a premise for further studies in applied sciences. Based on the lacking ultrastructural data about the reproductive systems of the Auchenorrhyncha, we carried out morphostructural investigations on the male reproductive system of B. brevis. Further, a first report of DNA barcoding analysis (amplification and sequencing of Cytochrome Oxidase I gene) has also been performed to characterize B. brevis compared to other congeneric species. From a morphological point of view, the male reproductive system of B. brevis has an organization comparable to the general anatomical features of most of the Auchenorrhyncha species; however, comparing our data with those concerning the different groups of Cicadomorpha, some considerations are discussed. As for the histological and ultrastructural investigations, our results show a secretory activity of the various examined structures, mainly in the lateral ejaculatory ducts and in the accessory glands. The latter, in particular, show morphostructural differences comparing the distal tract to the proximal one; moreover, the histochemical techniques showed the possible presence of a lipid component in the peculiar cytoplasmic granules found in the gland cells. The significance of these findings in the accessory glands is discussed. Finally, the ultrastructural features found in the seminal vesicles are different from those of the lateral ejaculatory ducts and are indicative of the different roles played by these structures in the organization of the spermatozoa bundles.     

X-ray microanalysis of uterine epithelial cells in culture

The ionic composition of the uterine fluid, secreted by the endometrium, is of importance for fertilization and embryonic development. Little, however, is known about the ion transport mechanisms in the uterine epithelial cells. Because it is difficult to study ion transport in this tissue in situ, a method was developed to culture mouse uterine epithelial cells for X-ray microanalysis in the electron microscope, in order to allow the study of ion transport. Our data suggest the presence of a number of ion transport mechanisms in the cultured uterine epithelial cells. The cells appear to possess a ouabain-sensitive Na⁺---K⁺-ATPase, an amiloride-sensitive Na⁺---H⁺ antiporter, cAMP- and Ca²⁺-activated chloride channels, and volume-activated chloride efflux and influx mechanisms. In addition, chloride efflux can be stimulated by cholinergic and alpha-adrenergic agonists. Only a few of these mechanisms had been studied previously in the uterine epithelium.     

Morphological and ultrastructural characterization of an unusual purple sulfur bacterium from a marine microbial-mat community

An unusual purple sulfur bacterium present in the pink layer of the Ebro Delta microbial mats has been identified through the study of its ultrastructural features. As pure cultures of this bacterium have not been obtained, due to its inability to grow in axenic conditions, only enrichment cultures where it reached at least 90% of total biomass have been considered. In enrichment cultures, the cells are rods that are 5.4+/-0.6 microm wide and 11.0+/-2.1 microm long. The color of the cell suspensions is pink to pinkish-red. Cells are motile by means of a polar tuft of flagella and multiply by binary fission. This bacterium possesses an extensive internal photosynthetic membrane system consisting of stacks of lamellae, contains bacteriochlorophyll a and carotenoids of normal spirilloxanthin series and deposits sulfur intracellularly. In natural samples, the most abundant phototrophic purple sulfur bacterium developing in this ecosystem has the same kind of intracytoplasmic membrane system, but the cells differ slightly in size and arrangement, in that they are ovoid, 4.2+/-0.5 microm wide and 6.0+/-1.4 microm long, and can be seen forming irregular non-motile clumps which are embedded in slime. Differences observed between field samples and enrichment cultures suggest that environmental conditions may bring about changes in the phenotypic characteristics of the cells. The morphological characteristics of the described bacterium resemble those of large Chromatia. However, this bacterium differs from known species in this group, particularly in terms of its photosynthetic membrane system and in its light absorption properties.     

Ultra-structure and histochemistry of digestive cells of Podisus nigrispinus (Hemiptera: Pentatomidae) fed with prey reared on bt-cotton

The toxic effects of Bt proteins from the body of the prey/host to predators and parasitoids have been investigated as a route of impact on non-target insects of Bt crops. This research aimed to analyze ultrastructural changes and histochemistry in digestive cells of the middle region of the midgut of Podisus nigrispinus fed, since its second instar, with Spodoptera frugiperda reared on Bt cotton variety Acala90 B, which expresses the toxin Cry 1Ac, and its non-Bt isoline Acala 90. Fragments of the midgut of P. nigrispinus were analyzed by electron microscopy. For the histochemical analysis, Bromophenol Blue, Periodic Acid Schiff von Kossa, Alcian Blue pH 2.5 and Sudan Black were used. The Cry1Ac toxin of Bt cotton ingested by S. frugiperda promotes a disorganization in the perimicrovillar matrix of P. nigrispinus (third trophic level), thus generating ultrastructural changes in the digestive cells, as elongation of microvilli, presence of spherocrystals and granules of different electron densities, in addition to altering the distribution pattern of glycogen, lipids and calcium of these cells in the median region of the midgut. Thus, we conclude that species moderately susceptible to Cry1Ac toxin, such as S. frugiperda, can acquire this toxin and expose it to P. nigrispinus, which can interfere with your ability to predation.     

LM and TEM study of the orthokeratinized and parakeratinized epithelium of the tongue in the domestic duck (Anas platyrhynchos f. domestica)

The previous histological studies of the lingual mucosa in birds characterized two types of keratinized epithelium, i.e. orthokeratinized and parakeratinized. These epithelia are composed of three layers: basal, intermediate and keratinized. The present study showed detailed ultrastructural features of cells in particular layers of two types of keratinized epithelia on the tongue in the domestic duck and defined structural differences.TEM observations showed a gradual reduction in cell organelles in the following layers, at increasing amounts of keratin fibers. The characteristic feature of the ortho- and parakeratinized epithelium is the presence of sub-layers in the intermediate layer, i.e. the upper and lower part, which results from the different shape of cell nuclei and dye affinity of the cytoplasm. The keratinized layer of ortho- and parakeratinized epithelium is built of two types of cells such as electron dark and light cells, which undergo exfoliation. The basic difference between the keratinized epithelia is the presence of flattened cell nuclei in the keratinized layer of the parakeratinized epithelium. The differentiating feature is also an arrangement of keratin fibers in the cell cytoplasm of the keratinized layer. The analysis of the thickness of the epithelium and the keratinized layer, indicated differences between keratinized epithelia, which result from two variants of performing protective functions, either through a thick keratinized layer or by a higher epithelium.Differences in the ultrastructure of the ortho- and parakeratinized epithelium are associated with mechanical functions of the epithelium resulting from different forces acting on the tongue during feeding activities.     

The rectum of Oxaea flavescens (Andrenidae) has a specialized structure among bees

The rectum of the bee Oxaea flavescens contains six hollow rectal papillae, in contrast to rectal pads found in others Hymenoptera. The rectal epithelium is formed by cubical cells with structural specializations for fluid transport, such as apical plasma membrane invaginations, endocytic vesicles, scalariform junctions, wide extracellular space and double-membrane vesicles. Globular-shaped cells form the rectal papillae with surface plasma membrane invaginations that vary from small depressions to very large sinuses. The cell-cell contact is narrow, exhibiting extensive regions with scalariform junction, while cytoplasmic free ribosome-like material is prominent. These ultrastructural features are discussed in relation to their role in excretion in this bee.     

应用于钙钛矿太阳能电池中金属氧化物电子传输材料的研究进展

基于有机金属卤化铅钙钛矿材料作为光活性层的太阳能电池(PSCs)已经获得了25.2%的认证效率,是除硅基太阳能电池外被认为最有可能实现商业化的太阳能电池之一。电子传输层是PSCs器件结构的最基本组成之一,其构成材料与光活性层的成膜质量、界面电荷的快速提取以及能级匹配等密切相关。因而,电子传输材料在PSCs的光伏性能及稳定性调控方面发挥着重要作用。本文对应用在PSCs中的金属氧化物电子传输材料进行了回顾与总结,着重强调了材料的纳米结构与制备工艺、半导体特性与分类以及掺杂与界面修饰等方面的研究进展,并对其今后的发展进行了展望。     

Microscopical methods promote the understanding of the integument biology of Rhinella ornata

In Rhinella ornata, the integument of different body regions was investigated using low-vacuum scanning electron and light microscopy through histochemical and immunohistochemical methods, and revealed the basic structure found in other anurans. Keratinocytes formed the keratinized squamous stratified epithelium, and flask cells occurred among the epidermal superficial layer. Just below the epidermis, the dermis was subdivided into a spongious dermis and a compact dermis. Mixed and granular glands were located in the spongious dermis, and myoepithelial cells surrounded their secretory portions. The Eberth-Katschenko (EK) layer occurred as basophilic areas between the spongious and compact dermis and throughout the spongious dermis. A series of alternating layers of bundles of collagenous fibers characterized the compact dermis, being firmly attached to a thin hypodermis. Regarding the morphological features, each integument region revealed distinct structural aspects. The dorsal integument was rougher than ventral, having conical tubercles and spines upon the verrucae. In the ventral and subgular regions, the slightly elevations are visualized, tubercles were absent but some spines occurred. The pelvic integument had a non-keratinized epidermis with an irregular profile and small poorly developed elevations. In addition, the EK layer was absent, and the presence of numerous blood vessels suggests its participation in water absorption and distribution. In the parotoid gland, the epidermis was similar to the dorsal integument; except that the reticular dermis was present, and contained three exocrine glandular types. Expression of cytokeratin was evident in the basal and intermediary layer, but absent in the cornified layer. Flask cells showed strong cytokeratin labeling. Consequently, the integument had the basic morphology, but exhibits regional characteristics, which may be related to the physiology of each surface.     

Histological and histochemical features of the oogenesis in the simultaneous protandric hermaphrodite shrimp Exhippolysmata oplophoroides (Decapoda: Caridea)

This study analyzes the dynamics of the vitellogenesis process in the simultaneous protandric hermaphrodite shrimp Exhippolysmata oplophoroides, based on light microscopic observations. The ovotestes of the shrimps at the different gonadal development stages were removed, fixed and submitted an usual histological procedure (HE) and histochemical techniques (Bromophenol Blue, PAS/Alcian Blue, and Von Kossa tests). The germinative cells were classified into oogonias, and oocytes in stages I–IV based on the following features: cell size, cytoplasm appearance, presence of yolk granules, lipid droplets, chorion, and chromatin patterns. In the male initial phase of the gonadal development, the ovotestes present mainly oogonia and oocytes I and II while in the functional hermaphrodite phase, oocytes III and IV predominate in the peripheral zone of the gonads. Oocytes with an atypical appearance of the cellular components indicative of reabsorption were also observed. This study showed an increasing accumulation of proteins, carbohydrates and lipids occurring as the germ cells develop, being the yolk elements deposited in a sequence, in which proteins and carbohydrates are the first to appear both by an endogenous as well as also by an exogenous origin. The presence of calcium was detected mainly in oocytes I, II and inside those in reabsorption, being posteriorly mobilized to chorion constitution and/or to hemolymph due to its role during molting. Although the similarity of the germ cells shape among the crustaceans, this first histochemical characterization of E. oplophoproides ovary increases the comprehension of oogenesis in a caridean simultaneous protandric hermaphrodite species.     

Phonon driven nonlinear electrical behavior in molecular devices

Electronic transport in a model molecular device coupled to local phonon modes is theoretically analyzed. The method allows for obtaining an accurate approximation of the system's quantum state irrespective of the electron and phonon energy scales. Nonlinear electrical features emerge from the calculated current-voltage characteristics. The quantum corrections with respect to the adiabatic limit characterize the transport scenario, and the polaronic reduction of the effective device-lead coupling plays a fundamental role in the unusual electrical features.     

Acousto–optical interaction in fishbone-like one-dimensional phoxonic crystal nanobeam

We have investigated the light emission properties in rubrene-doped nematic liquid crystal (LC) cells from the following three standpoints: (i) effect of the heating temperature during the sample preparation, (ii) role of the emissive LC layer thickness, and (iii) role of different LC types used as the emissive layer. As a result, the light-emitting LC cells simultaneously exhibit the features of electrochemiluminescent cells (the carrier transport is governed by an ionic conduction) as well as of organic light-emitting diodes (the luminance strongly depends on the emissive layer thickness). Furthermore, we report that devices with cyano group containing LCs exhibit higher luminance compared to a fluorinated LC.     

光栅光阀器件的结构改进与制作工艺研究

根据光栅光阀的工作原理,在结构上对传统的光栅光阀器件进行了改进,分析了改进后光栅光阀器件的光学特性、结构特性,以及制作工艺流程.改进后的光栅光阀结构中硅基底上设有二氧化硅隔离层,隔离层上沉积无定形硅作为牺牲层,可动梁的材料是氮化硅,固定梁为蒸镀的金属铝层.通过离子刻蚀的方法刻蚀图形,用化学腐蚀方法掏空牺牲层得到所需桥梁状结构.研究表明改进后的器件黑区范围小,驱动电压较低,光学效率较高,具有潜在的应用前景.     

Quantum Transport across Amorphous-Crystalline Interfaces in Tunnel Oxide Passivated Contact Solar Cells: Direct versus Defect-Assisted Tunneling

Tunnel oxide passivated contact solar cells have evolved into one of the most promising silicon solar cell concepts of the past decade,achieving a record efficiency of 25%.We study the transport mechanisms of realistic tunnel oxide structures,as encountered in tunnel oxide passivating contact(TOPCon) solar cells.Tunneling transport is affected by various factors,including oxide layer thickness,hydrogen passivation,and oxygen vacancies.When the thickness of the tunnel oxide layer increases,a faster decline of conductivity is obtained computationally than that observed experimentally.Direct tunneling seems not to explain the transport characteristics of tunnel oxide contacts.Indeed,it can be shown that recombination of multiple oxygen defects in a-SiO_x can generate atomic silicon nanowires in the tunnel layer.Accordingly,new and energetically favorable transmission channels are generated,which dramatically increase the total current,and could provide an explanation for our experimental results.Our work proves that hydrogenated silicon oxide(SiO_x:H) facilitates high-quality passivation,and features good electrical conductivity,making it a promising hydrogenation material for TOPCon solar cells.By carefully selecting the experimental conditions for tuning the SiO_x:H layer,we anticipate the simultaneous achievement of high open-circuit voltage and low contact resistance.     

Histochemical technique for the detection of chloride cells in fish

Chloride cells are responsible for ionic exchanges in the fish gill. These cells have been widely studied, considering its importance in vital functions of the gill, and because they proliferate when exposed to unfavorable environments. One of the main characteristic of these cells is an acidic cytoplasm, which has been used for identification through histochemical techniques with dyes such as Toluidine Blue and Hematoxylin and Eosin. However, these techniques can be problematic, since epithelial cells can, in certain situations, acquire acidic characteristics similar to those of chloride cells, thus staining in a similar way. Among other functions, chloride cells play a role in calcium uptake from the environment, and therefore have a high concentration of this element. Based on this information, this study aims at developing a specific protocol for the identification of chloride cells. With this purpose, the Von Kossa method specific for calcium was used combined with Hematoxylin counterstaining. Chloride cells had cytoplasm slightly stained with Hematoxylin and the presence of dark stained granules dispersed in the cytoplasm resulted from the Von Kossa reaction due to the calcium present in these cells. This was not found in any other gill cell. Thus, the technique used in this study was specific and efficient to identify chloride cells in fish gills.     

Morphological features and occurrence of degenerative characteristics in the hypopharyngeal glands of the paper wasp Polistes versicolor (Olivier) (Hymenoptera: Vespidae)

Different histochemical techniques were applied to examine the morphological features of the secretory cells of hypopharyngeal glands in the wasp Polistes versicolor. The results showed that most analyzed individuals present active glands with secretion stored in the cytoplasm. In some glands, morphological analyses revealed the presence of degenerative characteristics. Analyses of cellular integrity, however, did not detect dead cells. The results showed that, in P. versicolor, the development and regression of the hypopharyngeal glands were not age related, unlike glands of social bees.     

Testicular structure and description of the seminal pathway in Leporinus macrocephalus (Anostomidae, Teleostei)

The present study examined the testicular structure and the seminal pathway in freshwater fish Leporinus macrocephalus (Garavello and Britski, 1988). Twenty-five specimens of this species were studied. Testicular structure was analyzed using light and transmission electron microscopy. The testicular main ducts were examined by means of conventional histology, corrosion–cast technique and scanning electron microscopy. Additional techniques were applied for polysaccharides histochemistry and immunohistochemistry for androgen receptor. The testicular parenchyma was classified as the anastomosing tubular testis type with spermatogonia occurring along the lengths of the seminiferous tubules. The seminiferous tubules emptied directly into the testicular main ducts. The wall of the testicular main ducts in L. macrocephalus consisted of three layers: epithelium, connective tissue and peritoneum. The epithelium changed from simple cuboidal to pseudostratified. The histochemical analysis revealed the presence of granules PAS positive in the epithelial cells. The immunoreactivity to androgen receptor was noted in the testicular main ducts through all cytoplasmic areas of epithelial cells.