Central Lamella Research Articles

Eucalyptus-Based Glued Laminated Timber: Evaluation and Prediction of Its Properties by Non-Destructive Techniques

Eucalyptus-based glued laminated timber (glulam) was produced to determine the feasibility of a non-destructive method (drilling resistance) to predict the properties of structural elements and add value to lower-quality hardwood species. Glulam was manufactured with formaldehyde (Resorcinol), reference condition, and bio-based (Castor oil-based) adhesives in two assembly schemes, the core composed either of two continuous lamellae each 105 cm long, or of two formed by the juxtaposition of shorter boards (35 and 55 cm). The shear strength of the glue line (fv0), modulus of elasticity (Ec90), and strength (fc90) in compression perpendicular to the grain; delamination (DL); and main and extended glue line thicknesses were evaluated. The Resistograph equipment was used to perform the perforation perpendicular to the glue line (samples extracted from the glulam elements) to correlate the properties. The results of this research demonstrate that the scheme of the boards had little effect on the physical and mechanical properties evaluated (except the main glue line and delamination), and the drilling resistance (DR) presents a significant correlation with practically all properties evaluated (variations in density values and other properties are explained by variations in DR values), making it possible to estimate Ec90 and fc90 with desired precision (R2adj ≈ 80%). This highlights the feasibility of using this methodology in the quality control of glulam elements. It is concluded that regardless of the adhesive, elements comprising a 105 cm-length core and external lamellae (T1 and control) are indicated for external use, presenting low delamination. Short-length central lamellae adhesively glued with PUR (T2) are not recommended for external applications due to their susceptibility to delamination. However, T2 is indicated for internal environments due to its low production cost. This study also proved the efficiency of using models based on drilling resistance to estimate wood density and its resistance to compression perpendicular to the fiber.

Odorant transport in a hagfish

Odorant transport is of fundamental and applied importance. Using computational simulations, we studied odorant transport in an anatomically accurate model of the nasal passage of a hagfish (probably Eptatretus stoutii). We found that ambient water is sampled widely, with a significant ventral element. Additionally, there is a bilateral element to olfactory flow, which enters the single nostril in two narrow, laminar streams that are then split prior to the nasal chamber by the anterior edge of the central olfactory lamella. An appendage on this lamella directs a small portion (10–14%) of the overall nasal flow to the olfactory sensory channels. Much of the remaining flow is diverted away from the sensory channels by two peripheral channels. The anterior edge of the central olfactory lamella, together with a jet-impingement mechanism, disperses flow over the olfactory surfaces. Diffusion of odorant from bulk water to the olfactory surfaces is facilitated by the large surface area:volume ratio of the sensory channels, and by a resistance-based hydrodynamic mechanism that leads to long residence times (up to 4.5 s) in the sensory channels. With increasing volumetric flow rate, the rate of odorant transfer to the olfactory surfaces increases, but the efficiency of odorant uptake decreases, falling in the range 2–6%. Odorant flux decreases caudally across the olfactory surfaces, suggesting in vivo a preponderance of olfactory sensory neurons on the anterior part of each olfactory surface. We conclude that the hagfish has a subtle anatomy for locating and capturing odorant molecules.

Thermal protection properties of profiled timber with peat-vermiculite insulation

Today, the use of environmentally friendly materials is becoming increasingly important. The construction of energy-saving buildings with enclosing structures made of insulated profiled timber, is one of the most promising areas in low-rise construction.Materials having minimum negative impact on the environment during their operation, include new construction insulation materials based on peat-vermiculite granules. The paper studies the main physical properties of wooden exterior walls made of profiled timber, in which peat vermiculite is used as insulation, thermal conductivity of which ranges from 0.05 to 0.06 W/(m·K). For this purpose, numerical simulation is performed for the heat-mass transfer in wooden enclosing structures made of insulated timber with three different connector options.The temperature and heat flow distributions are obtained as a result of modeling stationary thermal conductivity processes in timber structures. It is shown that plywood connectors do not affect the thickness temperature distribution in wooden walls with peat-vermiculite insulation. An increase in thermal conductivity of insulation has no significant effect on the temperature difference along the connector axis or outside the region of its temperature influence.It is found that the thickness of the peat-vermiculite insulation layer should be at least 0.176 m to ensure the compliance with the main requirements for thermal protection properties of enclosing structures in the climatic conditions of Tomsk. The greatest heat loss with a minimum insulation thickness is observed for the wall made of profiled insulated timber with T-shaped connectors. A high-strength timber with the additional central lamella has the best thermal protection with the lowest insulation thickness.

Thermocapillary central lamella recess during droplet impacts onto a heated wall

We experimentally observe a new phenomenon, the formation of a toroidal region of lower film thickness in the center of the lamella formed during high Weber number water droplet impacts onto smooth heated walls. This region forms around the air bubble, which is entrapped during the initial impact phase at the impact center. Our study encompasses a variation of the droplet size, impact velocity, surface wettability and temperature. We show how this phenomenon can be explained considering a two-step process involving thermocapillary convection in two separate regions: The temperature gradient along the surface of the entrapped air bubble caused by heat conduction induces flow that pumps warmer liquid to the lamella-ambient interface due to the Marangoni effect. The non-uniform temperature distribution along it then causes fluid acceleration in the radial direction, depleting the fluid volume around the bubble in a self-amplifying manner. We use direct numerical simulations of a stagnant liquid film with an enclosed bubble at the wall to confirm this theory.

Biocompatibility and Transplantation Efficacy of the C-Clear Artificial Cornea in a Rabbit Chemical Burn Model.

We investigated the bioavailability and stability of a C-Clear artificial cornea in a rabbit chemical burn model. Thirty-six rabbits were divided into a control group (n = 16) and a chemical burn group that used NaOH solution (n = 20). After lamellar dissection, the central posterior lamella was excised using a 3 mm diameter trephine, and an artificial cornea was transplanted into the lamellar pocket. After 2 weeks, the central anterior lamella was excised using a 3 mm diameter trephine to secure a clean visual axis. We examined the anterior segment of the eyes weekly for 12 weeks after transplantation. Successful subjects whose artificial corneas were maintained stably for 12 weeks were euthanized and underwent histologic examinations. Artificial corneas remained stable for up to 12 weeks in 62.5 and 50% of rabbits in the control and chemical burn groups, respectively. Two rabbits in the chemical burn group showed the formation of a retroprosthetic membrane, and one rabbit with visual axis blockage underwent membrane removal using a Nd:YAG laser. In histologic examinations, adhesion between artificial cornea and peripheral corneal stoma was observed. In conclusion, we confirmed structural stability and biocompatibility of the C-Clear artificial cornea for up to 12 weeks after implantation in control and chemical burn groups.

Pleione xiushanensis (Orchidaceae), a new species from Mt. Wulingshan Region, China

Pleione xiushanensis, a new orchid plant from the Mt. Wulingshan Region of China, is illustrated and described based on morphological comparisons and phylogenetic analyses. The species is similar to P. bulbocodioides and P. pleionoides but differs from the former in that its lip lacks central lamellae and from the latter in that its lip exhibits fuchsia punctata. Additionally, the lip of P. bulbocodioides and P. pleionoides has 2 or 4 denticulate lamellae, but the lip of the new species has 2 internal integer lamellae and 2 external denticulate lamellae. Our phylogenomic evidence based on the nrITS sequence resolved P. xiushanensis as sister to P. jinhuana. P. jinhuana has 2 denticulate lamellae and shows margin erosion at the apical edge of the lip, but P. xiushanensis has 4 denticulate lamellae and shows no margin erosion of the lip.

Effects of Ethanolic Extracts of Fruits of Dennettia tripetala on Liver Function of Male Albino Rats

This study evaluated the effects of ethanolic extracts of fruits of Dennettia tripetala on liver function of male albino rats. Dennettia tripetala is an endemic plant of west tropical Africa that is known as pepper fruit. The fruit is known for its numerous medicinal properties such as antioxidant, anti-inflammatory and antidiarrhea. The plant materials were air dried and made into powder, 250g was used for the crude extraction using 70% ethanol. Ninety eight male albino rats were used in this study; forty eight were used for LD50 and fifty for the main experiment. The animals were randomly distributed into 5 groups of 10 animals each. The test animals were administered single dose of ethanolic extracts of fruits of D. tripetala (200 mg/kg and 400 mg/kg) daily for twenty-one days. The animals sacrificed at end of the 21 days. Blood sample was collected via cardiac puncture for biochemical analysis, while the liver was harvested for histological examination. A very high LD50 value of 4000 mg/kg body weight was recorded in this study. The results of biochemical parameters revealed that mean values of AST ALT and ALP were elevated significantly (p<0.05) in all the test groups, except ALP in group 4 which showed no significant alteration when compared to the control. Total protein, albumin and globulin showed no significant alteration in all the test groups; total and direct bilirubin decreased significantly in test groups 4 and 5, and increased in group 2, while indirect bilirubin showed no significant alteration in all the test groups. Photomicrograph of liver section of normal control rats (group 1) showed normal central vein, portal triad, sinusoids and lamella of hepatic cells as well as those in all the test groups.

Uso da ceratectomia superficial lamelar central automatizada no tratamento das ceratites superficiais pigmentares crônicas em cães

ABSTRACT Pigmentary superficial keratitis (PSK) is a chronic corneal disorder with different causes, which may include immune-mediated diseases and reactions to ultraviolet rays. This study aimed to evaluate the use of automated central lamellar superficial keratectomy (ACLSK) in the treatment of chronic pigmentary superficial keratitis (CPSK) in dogs. We enrolled 24 animals with CPSK and loss of visual function even after clinical treatment with preserved post-corneal transparent media, and the potential for recovery of visual function after surgical treatment. The microkeratome was positioned on the eye surface, and the central corneal lamellae were obtained after translation. With ACSLC, 21 animals (87.5%) recovered their visual function. In 3 animals (12.5%), the formation of granuloma and posterior central leukoma in the cornea compromised the transparency of the visual axis. This study concludes that ACLSK is a viable surgical alternative for the restoration of visual function in dogs with severe PSK, thus improving their quality of life. The short execution time of this procedure reduces the costs and anesthetic risks.

Manually prepared lamellae for Descemet stripping endothelial keratoplasty (Pachy-DSEK): comparison of four dissection depths.

This study aimed to compare four depths of manual dissection for the preparation of Descemet stripping endothelial keratoplasty lamellae. Eye bank corneas were randomized into four groups according to dissection depths: Pachy-100 (incision depth = central corneal thickness-safety margin of 100 µm), Pachy-50 (safety margin of 50 µm), Pachy-0 (no safety margin), and Pachy+50 (incision depth = central corneal thickness + 50 µm). All endothelial lamellae were prepared using a standardized method of manual dissection (Pachy-DSEK). The central, paracentral (3.0-mm zone), and peripheral (6.0-mm zone) lamella thicknesses and incision depths were measured by optical coherence tomography. The 3.0-mm and 6.0-mm zone central-to-peripheral thickness ratios were calculated. Endothelial perforation occurred only in the Pachy+50 group (n=3, 30%). Central lamella's thickness in Pachy-100, Pachy-50, Pachy-0, and Pachy+50 groups measured 185 ± 42 µm, 122 ± 29 µm, 114 ± 29 µm, and 58 ± 31 µm, respectively (p<0.001). The overall 3.0- and 6.0-mm C/P ratios were 0.97 ± 0.06 and 0.92 ± 0.14, respectively. Preoperative donor characteristics were not correlated with most thickness outcomes. The planned incision depth correlated significantly with most lamella's thickness parameters (p<0.001). The overall thickness of the lamella negatively correlated with the planned incision depth (p<0.001, r=-0.580). The best outcome was found in the Pachy-0 group, as 75% of the lamellae measured <130 µm and there was no endothelial perforation. By using a standardized method of dissection, most manually prepared lamellae presented a planar shape. Setting the incision depth to the central corneal thickness did not result in endothelial perforation and a high percentage of ultrathin lamellae was achieved.

Two new species of free-living nematodes from the East China Sea

Two new species of free-living marine nematodes of the genera Hopperia and Nemanema are described from the sublittoral sediment of the East China Sea. Hopperia macramphida sp. nov. is characterized by having large amphidial fovea with five turns; arcuate spicules with enlarged proximal end and central internal lamella extending one third of spicule length from proximal end; gubernaculum with bent apophyses, six papilliform precloacal supplements; and conico-cylindrical tail with swollen tip and terminal setae. Nemanema minutum sp. nov. is characterized by relatively smaller body size in the genus; large oval amphidial fovea; conical tail; slender spicules with alae and hooked proximal end; ring-like gubernaculum; and papilliform precloacal supplements with three short setae. An updated dichotomous key is provided for the 17 species of Hopperia.

Новий тип розвитку нюхової розетки в анциструса звичайного Ancistrus dolichopterus

Залежно від умов існування в риб по-різному розвинені сенсорні системи, а особливо нюховий аналізатор. Здатність риб реагувати на запахи залежить від форми нюхової розетки та морфології нюхових ламел. Уважають, що найкраще розвинений нюховий аналізатор у видів із білатеральною видовженою нюховою розеткою. Зазвичай нюхові розетки зі схожою морфологією характерні для видів із близьких родин або видів, які існують в однакових умовах. Орган нюху риб під час розвитку проходить стадії нюхової плакоди, нюхової ямки та нюхової камери з нюховою розеткою. Проте залишається нез’ясованим механізм розвитку нюхових розеток. Недостатньо уваги звернено на особливості формування центрального шва в нюхових розетках, додавання нових ламел у різних видів костистих риб. Для вивчення розвитку нюхової розетки білатерального типу анциструса звичайного Ancistrus dolichopterus вирощували в лабораторії гістології та морфогенезу Східноєвропейського національного університету імені Лесі Українки. Гістологічні препарати виготовлено за стандартними гістологічними методиками. В анциструса звичайного формування розетки відбувається у чотири етапи. На першому етапі відбувається закладка першої ламели в середній частині нюхової камери та її зростання з ростральною стінкою нюхової камери під час подальшого розвитку. На другому етапі вперше закладаються латеральна й медіальна ламели. На третьому відбувається закладка четвертої ламели з медіального боку від центрального шва. На четвертому етапі проходить спочатку симетрична відносно центрального шва закладка ламел, а потім у парних ламел латеральні ламели залягають ростральніше від медіальних. В Ancistrus dolichopterus центральний шов розвивається з першої центральної ламели, яка зі збільшенням довжини нюхової камери видовжується. Потовщення шва відбувається за рахунок прикріплення до нього нових бічних пар нюхових ламел у ростральній частині нюхової камери. Під час розвитку дистальний кінець центральної ламели зміщується латерально й ламела втрачає осьове положення. Білатеральна нюхова розетка Ancistrus dolichopterus набуває дефінітивного стану внаслідок додавання нових ламел ростральніше від уже розвинутих ламел, як і в більшості костистих риб, навіть з іншими типами нюхових розеток. Під час закладки четвертої ламели простежуємо порушення симетрії й формування ламели в цей період відбувається лише з одного боку від центрального шва. Усі наступні ламели закладаються попарно.

A re-description of Longicyatholaimus maldivarum Gerlach, 1964 (Nematoda, Cyatholamidae) with an emended identification key of the genus

Longicyatholaimus maldivarum was a species erected by Gerlach in 1964 from specimens found in the Maldivian archipelago. Due to the finding of additional representatives of this species, L. maldivarum is re-described with the addition of new morphological details mainly about males, because the information about female in the original description are very scarce. The newly found specimens showed a total body length higher than in the type specimens (1936–2063 µm vs. 1330 µm long) as well as the ratio of the total body length divided by maximum body diameter (22–28 vs. 27). The multispiral amphideal fovea showed 5 turns vs. 4 turns and Gerlach did not notice the presence of sub-ventral teeth that were clearly observed in the present specimens. The copulatory apparatus that perfectly matched the Gerlach description showed a central lamella mainly visible under confocal microscopy. A slightly lower ratio of the spicule length divided by anal body diameter (1 vs. 1.4) and longer gubernaculum (25–32 vs. 25 µm long) were noticed as well. Pre-cloacal supplements appeared very interesting for the presence of stout and conical setae protruding from cup-shaped structures. Supplements were more than in type species (8–9 vs. 7). Also the tail revealed some differences with a lower ratio of its total length divided by anal body diameter 6 vs. 7–8. The current list of 15 valid species of the genus was reduced to 10 species. In detail, we considered Longicyatholaimus heterurus and Longicyatholaimus sp. 3 species inquirendae for the absence of male specimens in the original description. We also excluded L. filicaudatus and L. tenuicaudatus because they were considered species inquirendae by Wieser &amp; Hopper (1967) and L. zosterae because it was transferred by Lorenzen (1972) to the genus Paralongicyatholaimus. The new morphological details observed for Longicyatholaimus maldivarum and the modified number of valid species of the genus required also a revision of the identification key.

Morphological study of the accommodative apparatus in the monkey eye.

For more than a century there has been debate concerning the mechanism of accommodation—whether the lens capsule or lens material itself determines the functional relationship between ciliary muscle contractility and lens deformation during refractive adaptation. This morphological study in monkey eyes investigates the composition and distribution of several connective tissue components in the accommodative apparatus relaying muscle force to lens organization. Elastin distributes on the marginal surface of the ciliary process. A zonule is composed of fibrillin produced by epithelial cells of the process. In the progress of extension over the posterior chamber, fibrils unite into strands and possess longitudinal plasticity. By induction of the elastin network, strands extend in a concentric direction covering the equatorial region of the capsule. Upon tethering to the lens, the strand ramifies into fibrils, penetrating deeply close to the epithelial layer of the lens and binding with the collagen of the intercellular spaces. Tight linkage of the zonule with the capsule transmits precise contractility. Inside the lens, the cortical layer's elastic connective tissue network forms widely spaced lamellae of crystalline fibers. In contrast, the central nuclear lamellae are tightly opposed. The accumulation of lamellae is greater in the anterior cortex than in the posterior, yielding a more variable anterior chamber depth in the visual axis. The plasticity of the zonule and connective tissue distribution inside the lens produces an adjustable configuration. Thus, tight linkage between the dynamism of the capsule with interaction of the lenticular flexibility provides a novel understanding of accommodation. Anat Rec, 298:630–636, 2015.

Three‐Dimensional Structure of the Nasal Passageway of a Hagfish and its Implications for Olfaction

From high-resolution (65 μm) data acquired by magnetic resonance imaging, we have reconstructed the nasal passageway of a single adult hagfish specimen (probably Eptatretus stoutii). We have used this reconstruction to investigate how the anatomy and morphometry of the nasal passageway influence the olfactory ability of the hagfish. We found that the long, broad section of the passageway preceding the nasal chamber will delay the response to an odor by 1-2 s. Diffusion of odorant to the olfactory epithelium, on which the olfactory sensitivity of an animal depends, will be favored by the relatively large surface area of the olfactory epithelium (∼140 mm(2) ) and a modest expansion in the nasal chamber. Oscillating flow (0.3-0.4 Hz) within the narrow (65-130 μm) sensory channels of the nasal chamber is laminar (Reynolds number ∼ 5) and quasi-steady (Womersley number generally less than one). Distribution of flow over the olfactory epithelium may be aided by: (a) a narrowing before the nasal chamber; (b) partial blockage of the nasal passageway by a protrusion on the central olfactory lamella; and (c) the inward inclination of the olfactory lamellae.

Femtosecond Laser-Assisted Mushroom Configuration Deep Anterior Lamellar Keratoplasty

To review patient outcomes after femtosecond laser-assisted mushroom configuration deep anterior lamellar keratoplasty. Seven eyes of seven patients with a mean age of 30 years underwent femtosecond laser-assisted mushroom configuration deep anterior lamellar keratoplasty from April 2008 to September 2008. Patients had keratoconus, corneal ectasia or scarring. Set for 100 mum of residual cornea, the femtosecond laser was used to create a mushroom-shaped recipient bed and donor button (having a larger anterior than posterior diameter). The posterior central lamella was manually dissected using Melles technique. Mean follow up was 4 months (range, 3-6.5 months). Preoperative mean best-corrected visual acuity was 20/95 (range, 20/40-20/400). Intraoperative complications included two cases (28.6%) of small Descemet membrane perforation. Postoperatively, there was one case of stromal rejection that resolved with topical steroids and two cases of steroid-related intraocular pressure rise that were treated with a prostaglandin analog. At 3 months, mean best-corrected visual acuity was 20/40 (range, 20/25-20/60), mean spherical equivalent refraction was -3.21 D (range, -6.75 D to plano), mean cylindrical refractive error was 3.57 D (range, 1.5-7 D), and mean keratometric cylinder measured 5.56 D (range, 3.79-7.00 D). Selective suture removal occurred in six patients (86%) at a mean of 3.8 months (range, 2-6 months) postoperatively. This preliminary series demonstrates that the use of the femtosecond laser to perform corneal cuts in a mushroom configuration for deep anterior lamellar keratoplasty is feasible. The mechanical stability and wound healing advantages for stepped corneal wounds should be considered in lamellar surgery.

Comparative Cellular Morphology Suggesting the Existence of Resident Dendritic Cells Within Immune Organs of Salmonids

This report is the first morphological description of cells that resemble dendritic cells, which appear to form resident populations within the spleen and anterior kidney of fish. Based on examination of three salmonid species, including, rainbow trout, brook trout, and Atlantic salmon, the cells were most abundant in the spleen, although they were always present in the anterior kidney. The cells appeared diffusely distributed, often near blood vessels of the spleen and kidney of healthy fish and within the epithelium, connective tissue, and blood vessels of rainbow trout gills with experimentally induced microsoporidial gill disease. The dendritic-like cells in this study contained granules that resemble Birbeck granules, which are considered to be morphological markers of Langerhans cells in mammals. The cells were approximately 6 mum in diameter and contained Birbeck-like (BL) granules localized near centrioles. Although the dendritic-like cells in the three salmonid species shared many similarities, morphological differences were found in the fine structure of the rod portion of the BL granules. Rainbow trout BL granules contained amorphous material, while the other salmonid species contained particulate material arranged in a square-lattice arrangement. The BL granules in the cells of Atlantic salmon had a narrow diameter and contained four layers of particulate material when sectioned longitudinally; two layers enveloped by the granule membrane and two central layers making up a central lamella, which is common in mammalian Birbeck granules.

Reactive changes in the adolescent porcine spine with disc degeneration due to endplate injury

Degenerative and reactive structural alterations occurring after experimentally-induced disc degeneration were evaluated using a porcine model. A cranial perforation was made through the L4 vertebral endplate into the nucleus pulposus. Three months later, the lumbar intervertebral disc and adjacent vertebrae were dissected, fixed in formalin and further processed for histopathological analyses. The results showed that there were nucleus pulposus fragments, rather than a distinct border between the nucleus and annulus fibrosus. The central lamellae were distorted and delamination of the outer anterior layers was observed. Blood vessels emerged from the adjacent tissue, penetrated the annulus and branched into the residues of the nucleus. Nerve fibres accompanying the blood vessels could be recognized in the disc within the connective scar tissue. The epiphyseal cartilage plates in the vertebrae were hypertrophic in several areas and there was bone formation directed towards the centre of the vertebral body and the disc. Hypertrophic hyaline cartilage, newly formed bone and scar tissue filled the injury canal. A slight chronic inflammatory reaction was evident along vascular buds. The reactive changes dominated over the degenerated features in the operated disc. Physiological loading enhanced the infiltration of various tissue types characterizing immature cartilage formation. Prominent neovascularisation of the central parts of the disc is likely to be of key importance in turning the degenerative features of the remaining tissue into reactive healthy structures.

Distribution of water quality parameters in two cross‐sections of the river Elbe measured with high local, temporal, and analytic resolution

AbstractThe river Elbe is a large eutrophic lowland river with high primary production and high phytoplankton biomass in the growing season. The objective of the study was to gain basic knowledge of the role of dead zones for phytoplankton distribution and the oxygen balance of the river Elbe. At two sampling stations water temperature, oxygen concentration, conductivity, pH value, turbidity, and chlorophyll fluorescence were measured with high precision to learn about the distribution of these parameters across the cross‐sections. The structures indicate differences in the intensity of physical and biological processes between the shallow waters near the shores, which are characterized by groyne fields, and the deep bulk flow. The conductivity clearly shows the high transverse mixing intensity in the groyne fields in contrast to the bulk flow. Groyne fields and the first, the groyne head near margin lamella of the bulk flow can be regarded as a unit. Groyne field results indicate higher primary production of phytoplankton, oxygen release, and higher pH. The turbidity of water entering the groyne fields decreases rapidly because of sedimentation within a short time. The groyne head lamella of the bulk flow sometimes shows higher chlorophyll fluorescence than the central lamella of the bulk flow and the water of the groyne field. The processes which contribute to the observed distribution are discussed, but could not yet be quantified. A modification of the dead zone model is proposed.

Species of Pseudorhabdosynochus Yamaguti, 1958 (Monogenea: Diplectanidae) from Epinephelus fasciatus and E. merra (Perciformes: Serranidae) off New Caledonia and other parts of the Indo-Pacific Ocean, with a comparison of measurements of specimens prepared using different methods, and a description of P. caledonicus n. sp.

Species of Pseudorhabdosynochus were studied from fresh specimens collected from Epinephelus fasciatus and E. merra off New Caledonia, South Pacific, and specimens deposited in Museums. Experiments on two species demonstrated that the sclerotised hollow organs, such as the quadriloculate male copulatory organ and the vagina, may show differences in measurements of up to 50% when flattened. P. caledonicus n. sp. is described from E. fasciatus in New Caledonia, on which it is relatively rare; it is distinguished on the basis of the quadriloculate organ, which has a very thin anterior wall, the sclerotised parts of the vagina in form of a straight tube with a star-shaped lateral structure, and the squamodiscs composed of 11 open rows of rodlets. P. cupatus (Young, 1969) is redescribed from abundant material from E. fasciatus off New Caledonia (new geographical record) and compared with paratype specimens from Australia (from E. fasciatus and E. merra) and specimens from E. fasciatus in the Red Sea (both herein redescribed and figured); a specimen was also found on a slide from E. merra off Vanuatu. P. melanesiensis (Laird, 1958) is redescribed from material from E. merra off New Caledonia (new geographical record) and compared with type-specimens (herein redescribed and figured) from the same host off Vanuatu. The structure of the sclerotised vagina in P. cupatus and P. melanesiensis is very similar, with a thin-walled tube and a heavily sclerotised structure with three loculi. P. vagampullum (Young, 1969) is redescribed from the paratypes from E. merra from Australia, but was not found in New Caledonia; specimens included among its paratypes (from E. merra in Australia), but different, are herein attributed to Pseudorhabdosynochus sp. 3. P. lantauensis (Beverley-Burton & Suriano, 1981) is redescribed from the paratype specimens from E. longispinis off Hong-Kong. A specimen found among the paratypes of P. cupatus belongs to a different species, herein designated as Pseudorhabdosynochus sp. 1. Specimens from E. longispinis off Hong-Kong, previously attributed to P. cupatus, are attributed to another species, Pseudorhabdosynochus sp. 2. The three species P. cupatus, Pseudorhabdosynochus sp. 1 and Pseudorhabdosynochus sp. 2 have in common a 'lamellosquamodisc' composed of central telescopic lamellae and peripheral rows of rodlets; they can be distinguished by the shape of the sclerotised vagina and measurements of the haptoral hard-parts. Specimens from E. longispinis off Hong-Kong, previously attributed to P. vagampullum, probably belong to a different species. Consequently, after these modified determinations, P. cupatus parasitises only E. fasciatus and E. merra, and P. melanesiensis and P. vagampullum parasitise only E. merra. With their wide geographical distribution and different species of Pseudorhabdosynochus in different localities, E. fasciatus and E. merra appear to represent excellent models for investigating monogenean biogeography in the Indo-Pacific Ocean.

Evidence for isothermal lamellar thickening at and behind the growth front as polyethylene crystallizes from the melt

The poorly characterized and little understood phenomenon of isothermal lamellar thickening, central to melt crystallization, has been studied morphologically in polyethylene rows, grown around high-melting fibres as linear nuclei revealing that thickening is a function of position within the morphology as well as of elapsed time. In contrast to polyethylene spherulites whose central lamellae are the thickest, in rows the first lamellae to form remain the thinnest because, being close-packed, they have no space into which to thicken. The thickness of lamellae at the growth front increases linearly with the logarithm of elapsed time but, as the thickest lamellae are found at finite radius, thickening must also occur behind the growth front. The data are consistent with a uniform rate of thickening throughout spherulitic polyethylene but melt crystallization must now be envisaged as occurring not at an interface in steady-state condition but at one whose thickness increases asymptotically and where interference will reduce thickening.