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In this study, we investigate the influence of absorber thickness on Cu2ZnSnS4 (CZTS) solar cells, ranging from 500 to 2000 nm, with nearly constant metallic composition. Despite the observed ZnS and SnS phases on the surface and backside of all absorber films, scanning electron microscopy, Raman scattering, and X-ray diffraction show no large variations in material quality for the different thicknesses. The open-circuit voltage ( Voc), short-circuit current and overall power conversion efficiency of the fabricated devices show an initial improvement as the absorber thickness increases but saturate when the thickness exceeds 750 nm. External quantum efficiency (EQE) measurements suggest that the current is mainly limited by collection losses. This can result from non-optimal bulk quality of the CZTS absorber (including the presence of secondary phases), which is apparently further reduced for the thinnest devices. The observed saturation of Voc agrees with the expected influence from strong interface recombination. Finally, an effective collection depth of 750-1000 nm for the minority carriers generated in the absorber can be estimated from EQE, indicating that the proper absorber thickness for our device process is approximately 1000 nm. Performance could be improved for thicker films, if the collection depth can be increased. [ABSTRACT FROM AUTHOR]

Abstract: We report on the electrical and physical properties of Cu2ZnSnSe4 (CZTSe) solar cells consisting of an absorber layer fabricated by selenization of sputtered Cu, Zn, Sn multilayers. Cross-section scanning electron microscopy images show that the polycrystalline absorber layers are approximately 1μm thick and that the typical grain size is of the order of 1μm. Energy-dispersive X-ray spectroscopy measurements show Cu-poor and Zn-rich compositions with Cu/(Zn+Sn)~0.8 and Zn/Sn~1.2. Solar cells are fabricated out of this absorber material using a standard process flow for chalcogenide solar cells. Under AM1.5G illumination, the best 1×1cm2 CZTSe solar cell shows an efficiency of 6.3% with a maximum short circuit current of 31.3mA/cm2, an open circuit voltage of 0.39V and a fill factor of 52%. Doping density of the absorber layers is derived using the drivel level capacitance profiling (DLCP) technique, showing low p-type doping density which seems to increase exponentially with the Zn/Sn ratio. Comparing the values obtained from DLCP to the ones derived from Mott–Schottky plots of the same devices, it is shown that for CZTSe care has to be taken when deriving the doping density. Similar to copper indium gallium selenide junctions, Mott–Schottky plots overestimate the amount of free carriers in the buffer due to the presence of fast defect states inside the bandgap. [Copyright &y& Elsevier]

Lardizabalaceae, one of seven families of Ranunculales, represent a monophyletic group. The family has functionally unisexual flowers with the organs in trimerous whorls, petaloid sepals and sometimes nectariferous petals. Among Ranunculales, Lardizabalaceae share several floral characters and climbing habit with Menispermaceae, but molecular analyses indicate that Circaeasteraceae and Lardizabalaceae form a strongly supported clade. Morphological and ontogenetic studies of flowers have proved to be a good complement to molecular data in clarifying relationships. Floral organogenesis has been studied in very few species of the family. This study investigates the comparative floral development of three species from three genera ( Decaisnea, Akebia and Holboellia) of Lardizabalaceae using scanning electron microscopy. Flowers have a whorled phyllotaxis. Within each whorl, the organs are initiated either simultaneously or in a rapid spiral sequence. In Akebia, six sepals are initiated, but one to three sepals of the second whorl do not further develop. The presence of three sepals in Akebia is thus a developmentally secondary simplification. The petals (if present) are retarded in early developmental stages; stamens and petals are different in shape from the beginning of development. The retarded petals may not be derived from staminodes in Lardizabalaceae. © 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2011, , 171-184. [ABSTRACT FROM AUTHOR]

Abstract: Scanning electron microscope (SEM) is necessary to demonstrate presence or absence of pit membranes in possible perforations or the type of pit membrane remnants in perforations in vessel element end-walls of angiosperms, but it was unconfirmed and questionable whether pit membrane absence in pits was affected by the processing and handling before SEM observations. To solve this question, the secondary xylem of four woody species from primitive angiosperms, Illicium henryi Diels. (Illiciaceae), Schisandra rubriflora (Franch.) Rehd. et Wils. (Schisandraceae), Tetracentron sinensis Oliv. and Trochodendron aralioides Sieb. & Zucc. (Trochodendraceae) was chosen and the following techniques were used: (1) fresh materials were examined in low-vacuum with ESEM. (2) Air-dried materials were examined both in low- and high-vacuum with ESEM. (3) Fresh materials fixed in several different fixatives were observed in low-vacuum, respectively. (4) Smooth surface of the material by paraffin section methods was examined in high-vacuum. (5) Materials treated by Jeffrey''s Fluid were observed in high-vacuum. Pit membranes and remnants in perforations of fresh material were little different from that of treated materials. Absence of the pit membrane in perforations (pits) in the end-wall was not attributed to the processing and handling. Information of pit membranes and remnants in perforations in end-wall based on the SEM observation might be validly claimed. [Copyright &y& Elsevier]

We examined the floral development of Dichocarpum fargesii, Thalictrum fargesii, Thalictrum przewalskii, and Aquilegia yabeana in Thalictroideae, Ranunculaceae, by scanning electron microscope. The sepals are initiated spirally in D. fargesii and A. yabeana, and in two pairs (with four sepals) or spirally (with five sepals) in T. fargesii and T. przewalskii. The petals in D. fargesii and A. yabeana and the stamens and carpels are initiated in a whorled pattern in all three genera. The floral phyllotaxis is whorled in these genera. The primordia of sepals are lunular and truncate, but that of petals and/or stamens are hemispherical, rounded, and much smaller than the sepal primordia. A relatively long plastochron exists between the last sepal and the first petal in D. fargesii and A. yabeana or the first stamen in T. fargesii and T. przewalskii. The similarity between the primordia of petals and stamens may indicate an evolutionary relationship between petals and stamens. The petals develop slower than the stamens in D. fargesii, but faster than stamens in A. yabeana. The early developmental stages of the staminodes in A. yabeana are similar to that of stamens, so they may be phylogenetically homologous organs. The carpel primordia are initiated in a single whorl; are lunular in shape and plicate in A. yabeana and D. fargesii; and are initiated spirally and hemispheric in shape and ascidiate in T. fargesii and T. przewlaskii. The stigma is everted and decurrent with unicellular papillae in T. fargesii and T. przewalskii; the head has unicellular papillae in D. fargesii and is smooth in A. yabeana. The floral development features of Aquilegia are unique in Thalictroideae. [ABSTRACT FROM AUTHOR]

Abstract: Floral development and floral phyllotaxis in species of Adonis, Callianthemum, and Trollius (Ranunculaceae) were studied with scanning electron microscopy. The floral organs are initiated in spiral sequence and the flowers have spiral phyllotaxis. The sepal primordia are broad, crescent-shaped, and truncate, but those of petals, stamens, and carpels are rather hemispherical. A relatively long plastochron appears to be present between the last sepal and the first petal as compared with the short and equal plastochrones of all subsequent floral organs. Maturation of the stamens within the androecium appears to be centripetal. The carpels have a short ascidiate zone. Placentation is uniformly lateral, even in Adonis and Callianthemum, which have only one fertile ovule per carpel (versus median in other genera of Ranunculoideae with a single fertile ovule). In Adonis and Callianthemum at the tip of the carpel the ventral slit is gaping and the stigma is broadly exposed, whereas in Trollius the stigma is narrower and more pronouncedly decurrent along the ventral slit. The petals in Callianthemum and Trollius are more conspicuously delayed in development than those in Adonis as compared with sepals and stamens. A short carpel stipe is formed early in Callianthemum but later in Adonis and Trollius. In Trollius farreri (commonly having only five carpels in contrast to other species of Trollius) the carpels form a single (spiral) series. Thus floral development is similar in all three genera and, at a lower level, Adonis and Callianthemum are especially close but have different autapomorphies, which reflects the current classification of the genera. [Copyright &y& Elsevier]

Floral morphogenesis and the development of Cercidiphyllum japonicum Sieb. et Zucc. were observed by scanning electron microscopy (SEM). The results showed that the pistillate inflorescences were congested spikes with the flowers arranged opposite. Great differences between the so-called “bract” and the vegetative leaf were observed both in morphogenesis and morphology. In morphogenesis, the “bract” primordium is crescent-shaped, truncated at the apex and not conduplicate, has no stipule primordium at the base but does have some inconspicuous teeth in the margin that are not glandular. The leaf primordium is triangular, cycloidal at the apex, conduplicate, has two stipule primordia at the base, has one gland-tooth at the apex occurring at first and some gland-teeth in the margin that occur later. In morphology, the “bract” is also different to the vegetative leaf in some characteristics that were also illustrated in the present paper. Based on the hypothesis that the bract is more similar to the vegetative leaf than the tepal, we considered that the so-called “bract” of C. japonicum might be the tepal of the pistillate flower in morphological nature. Therefore, each pistillate flower contains a tepal and a carpel. We did not find any trace of other floral organs in the morphogenesis of the pistillate flower. Therefore we considered that the unicarpellate status of extant Cercidiphyllum might be to highly reduce and advance characteristics that make the extant Cercidiphyllum isolated from both fossil Cercidiphyllum-like plants and its extant affinities. [ABSTRACT FROM AUTHOR]

• Floral structures are variable in Eranthis. • The stamen number is the main contributor to structural variation. • Morphological variation in Eranthis mainly occurred in petals. • Both sepal and petal numbers fit the modified error function. There is wide diversity in flower structure and pattern in nature. The number and morphological variation of flower organs in Eranthis of the family Ranunculaceae is high, but the pattern of flower structure variation in this genus is unclear. In this study, the morphological and numerical variation in organs of Eranthis stellata Maxim. and Eranthis lobulata W. T. Wang were observed with stereomicroscopy and scanning electron microscopy, and the patterns of variation were summarized statistically. The results showed the following: (1) The structural patterns of the two species of Eranthis were not stable. There were 232 flower structural patterns among 300 individuals of E. stellata and 55 among 100 individuals of E. lobulata. The number of floral organs in E. lobulata was significantly less than that in E. stellata. (2) The morphological variation in flower organs in Eranthis mainly occurred in petals, especially in the upper lip, pseudonectaries and lower lip, e.g., the number of lobes, and pseudonectaries and inconsistency in the upper lip edge. (3) The coefficient of variation (CV) of flower organs was greater than 20%, with some values close to 40%, which indicates that the number of floral organs of the two species differ substantially, and that the number of floral organs was extremely unstable. The range in stamen number was the largest while that in sepal number was the smallest, and this fluctuation might be caused by the spiral phyllotaxis of floral organs. [ABSTRACT FROM AUTHOR]

Abstract: A functional polymer, poly(styrene-stat-acrylonitrile-stat-vinyl-2,4-diamino-1,3,5-triazine) (modified SAN, mSAN) with 13.6% triazine units, was synthesized. Using mSANs as the functional polymers and poly(styrene-stat-acrylonitriles) (SANs) as the matrix polymers, the molecularly imprinted polymer (MIP) membranes with (S)-5-benzylhydantoin (S-BZH) as template and the Blank membranes without S-BZH were prepared via the water-assisted method. Scanning electron microscopy (SEM) measurement revealed an ordered porous structure on the surface and a sponge-like porous structure in the cross-section of the MIP membranes. Further, the permeation experiments of the template S-BZH and its analogues in methanol solution were carried out with MIP as well as Blank membranes; the results provided evidence for imprint effect of the ordered porous membranes. [Copyright &y& Elsevier]

Menispermaceae is one of the core groups of Ranunculales. The single fertile ovule in each ovary in Menispermaceae varies greatly in integument number, micropyle formation, and integument lobe. However, data regarding ovule morphogenesis in the family are very limited. In this study, we document ovule development of selected species in the Menispermaceae using scanning electron microscopy and light microscopy. Ovule development in Menispermaceae shows the following characteristics. Two ovules are initiated in a young carpel, one of them degenerates gradually and the other develops into a fertile ovule in subsequent stages. Bitegmic in Sinomenium Diels. and Cocculus DC. and unitegmic in Stephania Lour. The formation of unitegmy is probably due to integumentary shifting. The annularly initiated inner integument is of dermal origin and has 2–3 cell layers in the family, but the semi‐annularly initiated outer integument is of both dermal and subdermal origin. Both inner and outer integument are cup‐shaped at maturity. The cup‐shaped outer integument is formed due to the outer integument's extension to the concave (adaxial) side of the funiculus. The obturator is well developed and consists of 2–3 cell layers in Cocculus or 9–11 cell layers in Stephania. Ovule development of Menispermaceae suggests some common characteristics between Cocculus and Sinomenium, and derived unitegmy supports molecular data that indicate Stephania is one of the late‐diverging lineages in the family. Integument lobations are present. The sterile ovule shows variations in the degeneration process. These results will provide evidence for exploring the evolution of ovules in Ranunculales. [ABSTRACT FROM AUTHOR]

• Petal spurs in Aquilegia kansuensis, A. rockii, A. semicalcarata and A. ecalcarata have different lengths and nectary structures. • Early petal development is similar, and petals undergo delayed development, resulting in different mature petals via developmental remodeling. • There is no obvious one-to-one correspondence between spur length and pollinators in the four species of Aquilegia , and abiotic factors may be an important explanation for spur lengths in our study. The diversification of spur length in Aquilegia is often thought to be driven by pollinators. In this study, the morphology and pollination biology of four sympatric Aquilegia species distributed in China with different petal spur lengths were investigated through scanning electron microscopy, light microscopy, and field observations and measurements. The morphology and spur lengths of the four Aquilegia species differed: Aquilegia kansuensis has long incurved spurs (14.82 ± 0.18 mm), A. rockii has long straight spurs (16.34 ± 0.18 mm), A. semicalcarata has short slender spurs (5.16 ± 0.17 mm), and A. ecalcarata is effectively spurless (1.20 ± 0.03 mm). Early petal development was similar among the species; petals undergo initiation and delayed development, resulting in mature petals with different spur lengths and morphologies via developmental remodeling. The long spurs of A. kansuensis and A. rockii were derived from an increased cell number and anisotropic cell expansion, with well-developed secretory tissue forming at the spur bottom. No secretory tissue formed in the spurs of A. semicalcarata and A. ecalcarata , even though their cell number increased. Although their spur morphology and nectary structure show considerable differences, the pollination systems of the four species are similar. Rhingia campestris is the dominant pollinator of A. kansuensis, A. semicalcarata , and A. ecalcarata , whereas Pipiza familiaris is the dominant pollinator of A. rockii. Both R. campestris and P. familiaris forage for pollen when visiting flowers. Given that the four species studied differ in spur length but are all pollinated by short proboscid pollinators, there is no obvious one-to-one correspondence between spur length and pollinator mouthpart length in A. rockii, A. kansuensis, A. semicalcarata and A. ecalcarata , which is similar to the pattern in the European Aquilegia alpina , and abiotic factors may be an important explanation for spur lengths in our study. [ABSTRACT FROM AUTHOR]

The development of inflorescences and flowers of three species of Ranunculus and three allied genera ( Ceratocephala, Halerpestes, and Oxygraphis) (Ranunculeae, Ranunculaceae) was studied comparatively using scanning electron microscopy (SEM). Our results showed that both the inflorescence branching patterns and the floral morphogenesis in Ranunculeae are extremely labile. Inflorescences range from a thyrsoid to a solitary flower, with intermediate branching patterns in which sometimes only the terminal flower of the inflorescence main axis fully develops, such as in Ceratocephala and Halerpestes. Only in Oxygraphis is the flower truly solitary. In all species, sepal primordia are broad, crescent-shaped, and truncate, and the primordia of petals, stamens, and carpels are rather small and hemispherical, and very similar to each other. The plastochron between the last sepal and the first petal is relatively long. At the onset of androecium or gynoecium development, the regular spiral pattern of the perianth may become irregular in Ceratocephala and Oxygraphis, whereas spiral and whorled patterns may co-occur in Ranunculus and Halerpestes. The development of the petals is delayed with regard to that of the other floral organs in all species studied here, except for Oxygraphis. Our study confirms that, for solitary flowers, increased number of petals and the shape of the ventral nectary may have evolved independently many times, as suggested by earlier molecular phylogenetic studies and ancestral character reconstructions. With respect to the remainder of the tribe, Oxygraphis displays several autapomorphies, such as nondelayed development and increased number of petals, which will be of interest for comparative molecular developmental studies. [ABSTRACT FROM AUTHOR]

Background and Aims Preliminary field observations in 2001 and 2002 suggested that Kingdonia uniflora (Circaeasteraceae, Ranunculales) exhibits heterodichogamy, an unusual kind of reproductive heteromorphy, hitherto unreported in Ranunculales and known from only one other genus in basal eudicots. Methods During several subsequent years flowers were observed in the field. Flowers were fixed in FAA and studied with microtome sections series and with the scanning electron microscope. Key Results The flowers proved to be heterodichogamous, with protandrous and protogynous morphs, which have a 1 : 1 ratio. Both morphs equally set fruit. Each year a single flower is formed at the tip of a rhizome or more rarely two flowers. The flowers are already open when they appear at the soil surface, before they are receptive and before pollen is dispersed. In both floral morphs the styles elongate early and the stigmas are positioned above the anthers before anthesis begins. In protogynous flowers the stigmas become receptive in this position; later the styles become reflexed and then the anthers dehisce. In contrast, in protandrous flowers the stamen filaments elongate during early anthesis such that the dehiscing anthers come to lie above the (still unreceptive) stigmas; after dehiscence of all anthers in a flower the styles begin to elongate and become receptive. Conclusions This is the first record of heterodichogamy in a representative of Ranunculales, in an herbaceous eudicot, and in a plant with uniflorous ramets. The occurrence of heterodichogamy in Kingdonia in which clonal reproduction appears to be dominant might be an adaptation to avoid mating between the ramets from a common mother individual (genet). [ABSTRACT FROM PUBLISHER]

Abstract: For almost 150 years, the two monotypic genera Trochodendron and Tetracentron (Trochodendraceae) have been considered to share an unusual and primitive feature in angiosperms – the lack of vessels in their wood. Therefore, they have been classified in a basal position in the angiosperms. Our observations by light microscopy, low-vacuum environmental scanning electron microscopy (ESEM) and high-vacuum scanning electron microscopy (SEM) both in fresh and FAA-fixed materials consistently showed the presence of tracheary elements differentiated into two types in both genera. In Trochodendron, the tracheary elements can be divided into perforate vessel elements and imperforate fiber-tracheids and tracheids. The vessel elements show end and lateral walls. The pits on the end walls are elongate- broadened and do not have membranes or only a few remnants of them forming the perforation plates. The fiber-tracheids show crossfield pit pairs and sharp ends, and the tracheids show bordered pits. In Tetracentron, the tracheary elements comprise vessel elements and fibers. The vessel elements are similar to those of Trochodendron, whereas the fibers have no crossfield pit pairs but, rather, elliptical pits and sharp ends. Thus, both Trochodendron and Tetracentron are vessel bearing rather than vesselless, although their vessel elements are primitive. [Copyright &y& Elsevier]

Abstract: Sulfonated polysulfones (SPSF) with different sulfonation degrees were prepared by reaction of polysulfone with chlorosulfonic acid. The honeycomb films were fabricated by the breath figure method from freshly prepared SPSF/chloroform solutions. Furthermore, using the ordered porous SPSF films as template, honeycomb polyaniline (PANI) composite films were prepared by a simple one-step chemical oxidation polymerization of aniline. The surface morphology and conductivity of the PANI/SPSF composite film were characterized by environmental scanning electron microscopy and four-probe technique, respectively. The results indicate that the SPSF honeycomb ordered film played the role as template in controlling the morphology of the PANI/SPSF composite film with the porous and electrically conductive surface. [Copyright &y& Elsevier]

• Stamen initiation and early development in male and female flowers are similar. • Staminodes in female flowers develop abnormally late with the anthers degenerating to different degrees. • Staminode morphology varies from staminiform, spoon-shaped, navicular, tongue-shaped to petaloid structures. • Anther wall formation is the basic type, simultaneous cytokinesis results in tetrahedral tetrads. The stamen is an extremely important reproductive organ in angiosperms. Androecia are the places where pollen is produced and show diversity in number and form; some are even reduced to staminodes or nectary structures in Ranunculales, but the development, morphology and structure of staminodes are completely unknown in Menispermaceae. In this study, the androecium development of Cocculus orbiculatus (L.) DC. was observed in detail for the first time under scanning electron microscopy and light microscopy. The results show that 1) stamen initiation and early development in male and female flowers are similar, while the staminodes in female flowers develop abnormally at later developmental stages, with the anthers degenerating to different degrees and becoming more or less flat structures; 2) in female flowers, the morphology and structures of staminodes are diverse: staminiform staminodes with tiny indehiscent anthers where 2-celled pollen grains or tetrads could be found in locules, or spoon-shaped, navicular, tongue-shaped and petaloid flat structures with an apex covered with secretions on the ventral surface; 3) in male flowers, the meiosis of the microspore mother cells occurs with simultaneous cytokinesis, the tetrads are tetrahedral, and the 2-celled pollen grains are tricolpate. In addition, the anther wall formation is the basic type. Compared to those of other groups in Ranunculales, the staminodes in Menispermaceae share some common characteristics with those of Lardizabalaceae, such as their position, number, size, morphology and degradation degree. [ABSTRACT FROM AUTHOR]