Lamellar Type Research Articles

Histological identification of bone fragments in archaeology: telling humans apart from horses and cattle

AbstractIn archaeology, it is not always possible to identify bone fragments. A novel approach was chosen to assess the potential of histology as an identification tool in those instances in which macroscopical study (e.g. by means of bone surface texture) has failed. This study concentrated on the diaphyses of long bones in three species of comparable size which are relevant to archaeology. Late juvenile and adult human diaphyseal bone structure was compared with the bone structure of horses and cattle. Since bone structure can differ even within a single bone, the restrictions in terms of bone category, bone part and species were deemed necessary for the development of a useful identification method for archaeological bone. The reference series comprised long bones from several individuals to broaden the insight into variations in diaphyseal bone structure within a single species.A general difference in the primary bone types was found between humans and the two large mammals. Human bone displayed lamellar bone types, whereas horses and cattle showed fibrous bone types. The only exceptions were separated growth layers. A difference in the secondary bone structure was also observed. A large number of connecting, primary (Volkmann's) canals, giving the secondary bone a reticular aspect, were common in horses and cattle. They were not, however, present in the human bones studied.To confirm the validity and applicability of these differences, a blind test was conducted on 15 diaphyseal fragments of identified long bones from archaeological sites. The results were very promising. Although four fragments could not be identified due to severe degradation, all the others were correctly attributed. Copyright © 2006 John Wiley & Sons, Ltd.

Vehicles based on a sugar surfactant: Colloidal structure and its impact on in vitro/in vivo hydrocortisone permeation

An emerging class of natural surfactants, named alkylpolyglucosides, which can form both, the thermotropic and the lyotropic liquid crystalline phases, were focused. The aim of the study was to integrate some physicochemical properties (characterised through the polarization and transmission electron microscopy, wide-angle X-ray diffraction, thermal analysis and rheology) of the three formulations based on cetearyl glucoside and cetearyl alcohol, with the in vitro (the artificial skin constructs) and in vivo bioavailability of hydrocortisone (HC), in comparison with a standard pharmacopoeial vehicle. The parameters measured in vivo were erythema index (an instrumental human skin blanching assay), transepidermal water loss (TEWL) and stratum corneum hydration. A complex colloidal structure of lamellar liquid crystalline and lamellar gel crystalline type was deduced for sugar surfactant-based vehicles. In dependence on surfactant/water/oil ratio, several thermodinamically variable fractions of water were predicted. Rheological profile of the vehicle appeared to influence the in vitro profile of permeation. A surplus of total amount of drug permeated in vitro from the alkylpolyglucoside-based vehicles coincided with the more pronounced increase of TEWL and less marked blanching action of HC from the selected alkylpolyglucoside-based vehicle tested in vivo, related to the pharmacopoeial one. These findings imply an enhanced delivery of HC from this vehicle and its putative penetration enhancing effect, probably dependent on specific distribution of the vehicle's inherent water.

The liquid crystalline phases formed by linear-dodecylbenzene sulphonic acid during neutralisation with sodium carbonate

The liquid crystals and other phases formed when dodecyl-p-benzene sulphonic acid (DBSA) is “dry-neutralised” with sodium carbonate to form sodium dodecylbenzene sulphonate (NaDBS) have been investigated using optical microscopy, X-ray diffraction and differential scanning calorimetry. In addition, the phases formed by DBSA with water have also been investigated using the same methods. For the DBSA/water system, liquid phases are formed for the surfactant-rich and water-rich samples, whilst a lamellar phase occurs over an intermediate composition range of ca. 35/65-90/10 DBSA/water (by weight). There are no solid hydrates or “acid/soap” solid phases present. In the “dry-neutralised” system, CO2 is lost during the reaction, but half a mole of water per mole of NaDBS remains in the system. The fully neutralised NaDBS is a soft solid that contains at least three different mesophase structures at ambient temperature, probably of the lamellar type. These phases exist down to ca. 80% neutralisation and appear to coalesce into a single phase above ca. 80°C, and take several days to re-form on cooling. Several low-intensity, high-angle X-ray reflections are also observed at low temperatures implying that at least one of the phases has more order than a simple lamellar phase. Over ca. 30–55% neutralisation there is a single lamellar phase above 0°C. Between ca. 60% and ca. 80% neutralisation the phase structure is much more complex. Several layer phases are present, with numerous low-intensity, high-angle reflections. These phases do not fully coalesce by 120°C, and do not immediately revert to the original structure on cooling. It is suggested that the more complex X-ray patterns indicate the possible presence of separate “acid/soap”-type phases. The presence of multiple phases and the slow relaxation to more stable structures after heating will have an important influence on the formulation of low water content products with NaDBS.

Long‐term cryopreservation of dental pulp stem cells (SBP‐DPSCs) and their differentiated osteoblasts: A cell source for tissue repair

It is not known whether cells derived from stem cells retain their differentiation and morpho-functional properties after long-term cryopreservation. This information is of importance to evaluate their potential for long-term storage with a view to subsequent use in therapy. Here, we describe the morpho-functional properties of dental pulp stem cells (SBP-DPSCs), and of their differentiated osteoblasts, recovered after long-term cryopreservation. After storage for 2 years, we found that stem cells are still capable of differentiation, and that their differentiated cytotypes proliferate and produce woven bone tissue. In addition, cells still express all their respective surface antigens, confirming cellular integrity. In particular, SBP-DPSCs differentiated into pre-osteoblasts, showing diffuse positivity for ALP, BAP, RUNX-2, and calcein. Recovered osteoblasts expressed bone-specific markers and were easily recognizable ultrastructurally, with no alterations observed at this level. In addition, after in vivo transplantation, woven bone converted into a 3D lamellar bone type. Therefore, dental pulp stem cells and their osteoblast-derived cells can be long-term cryopreserved and may prove to be attractive for clinical applications.

Miscibility and properties of linear poly( l-lactide)/branched poly( l-lactide) copolyester blends

Polymer blends consisting of linear poly( l-lactide) (PLLA) and different proportions of dendritic PLLA-based copolyesters ( hb-PLLA) characterized by different degrees of branching (DB) were obtained in melt. The solid-state properties of poly( l-lactide)s and their blends were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), atomic force microscopy (AFM) and stress–strain measurements. DSC and DMA methods proved miscibility of PLLA/ hb-PLLA blends for the studied composition range. AFM indicated that no phase separation occurs in PLLA/ hb-PLLA blends and that PLLA and hb-PLLA cocrystallize in one single lamellae type. The mechanical characteristics of PLLA/ hb-PLLA blends deteriorated with an increase of the DB and with changing blend composition. Susceptibility of the blends to biodegradation was studied by measuring the weight loss in two different biodegradation media. PLLA/ hb-PLLA blends showed more pronounced hydrophilic character and higher susceptibility to biodegradation with an increase in the degree of branching.

Preparation and photocatalytic activity of titania particulate film with mesostructured silica as binder

TiO 2 (titania) particulate films with mesostructured silica (SiO 2) as binder were prepared by drying glass substrate coated with an aqueous mixture of titania particles, tetramethoxysilane (TMOS) and cetyltrimetylammonium bromide (CTAB) at appropriate temperature. X-ray diffraction (XRD) and IR absorption measurements on the obtained films revealed the formation of titania particles/silica composite thin film. XRD patterns at low angle region on these films indicated silica binder has well-ordered lamellar type mesostructure. These films show characteristic properties on both high absorption ability and photocatalytic activity to oxidative degradation of gaseous 2-propanol.

Epidermolytic hyperkeratosis with rickets

A 6-year-old child presented with generalized hyperkeratosis, most marked over the flexures; windswept deformity of the legs; and limping since 3 years. On the basis of the clinical, histopathologic and biochemical findings, he was diagnosed as a case of epidermolytic hyperkeratosis with rickets. He was treated with parenteral vitamin D3 and calcium supplements orally. Nutritional rickets has been reported in children with various types of ichthyosis like lamellar and X-linked types. We report this case of epidermolytic hyperkeratosis with rickets for its rarity.

Anisotropic Microstructure and Hydrogen Permeability of Nb-Ti-Ni Duplex Phase Alloy Prepared by Hot Forging-Rolling Technique

AbstractIt has been demonstrated that the as-cast Nb40Ti30Ni30 duplex phase alloy, which consists of the primary (Nb, Ti) solid solution and the fine lamellar type eutectic {TiNi+(Nb, Ti)} phase, shows higher hydrogen permeability ¶ than that of pure Pd without the hydrogen embrittlement at 673K. In this alloy, the eutectic phase contributes to the suppression of the hydrogen embrittlement, while the primary one does mainly to the hydrogen permeation. It is important to note that even if the eutectic microstructure disappears and is replaced by the small spherical (Nb, Ti) phase embedded in the TiNi matrix by rolling and subsequent annealing, its high hydrogen permeability and large resistance to the hydrogen embrittlement are sustained. Furthermore, the present authors have observed that the primary (Nb, Ti) phase is largely elongated along the rolling direction. Consequently, it is expected that rolled and annealed Nb-Ti-Ni alloys show the large anisotropy of the microstructure and the hydrogen permeability. In the present work, the microstructure and hydrogen permeability ¶nof the Nb40Ti30Ni30 alloy after rolling and annealing treatments are examined in order to develop highly hydrogen permeable alloys utilizing the anisotropic microstructure.The primary (Nb, Ti) phase and the very fine eutectic {TiNi+(Nb, Ti)} phase are observed in the as-cast Nb40Ti30Ni30 alloy by scanning electron microscopy (SEM). The X-ray diffractometry (XRD) indicates that this alloy consists of the B2-TiNi intermetallic compounds and the bcc- (Nb, Ti) solid solution. The primary (Nb, Ti) phase is largely elongated along the rolling direction by forging and subsequent rolling at 1173 K. On the other hand, the eutectic microstructure becomes unclear with increasing the rolling reduction. The composite alloys in which the (Nb, Ti) phase is elongated along to the rolling direction are obtained by 69 % rolling reduction. ¶n of this sample is four times higher than that of as-cast one. On the other hand, ¶ for the sample vertical to the rolling direction is reduced to about one third of that of as-cast one. Thus, the hydrogen permeability of the Nb40Ti30Ni30 alloy varies about ten times or more depending on the direction of the primary¡]Nb, Ti¡^ phase. We conclude that it is possible to produce highly hydrogen permeable Nb-Ti-Ni alloys using the anisotropy of the microstructure prepared by hot forging and rolling.

Risk Factors for the Development of Aphakic Glaucoma After Congenital Cataract Surgery

It is well-known that lensectomy surgery during the first year of life increases one's risk of aphakic glaucoma. However, it is controversial whether there is a specific time period during the first year of life after which performing lensectomy surgery has a lower risk of aphakic glaucoma development. A retrospective chart review was performed of all patients seen by a pediatric glaucoma specialist from 1970 to 2003. Patients were included in the study if they underwent congenital cataract surgery. Cataracts were defined as congenital if they were identified within the first 6 months of life, were dominantly inherited, or were of the lamellar type. Aphakic glaucoma was defined as having repeated intraocular pressures > 25 mm Hg after congenital cataract surgery. Patients were excluded if they had any conditions that were independently associated with glaucoma. A total of 368 eyes of 258 patients were included in the study. Of these, 216 (58.7%) eyes of 150 patients developed aphakic glaucoma. Risk factors of greatest significance (P < .0001) included having lensectomy within the first year of life and the development of postoperative complications. No specific age for lensectomy during the first year of life was associated with a decreased risk for development of aphakic glaucoma. Surgery for congenital cataracts should not be delayed if the only reason for delay is to prevent the development of aphakic glaucoma.

Morphological characterization of nylon‐6 nanocomposite following a large‐scale simple shear process

AbstractA commercial grade nylon‐6/clay nanocomposite (from Ube industries) is subjected to a large‐scale simple shear orientation process and the resulting morphology is investigated. Both the orientation and aspect ratio of nanoclays, which can be altered by the simple shear process, are studied. The incorporation of well‐dispersed nanoclays into the nylon matrix greatly reduces the nylon chain mobility as well as the percent crystallinity. Two types of lamellar orientation have been found, as revealed by small‐angle X‐ray scattering. One type of lamellae is oriented ∼41° away from the clay surface, whereas the simple shear process induces another weakly preferred lamellar orientation nearly perpendicular to the clay surface. The formation of the above lamellar orientations appears to be related to both orientation of the clay in the nanocomposite and the simple shear process. The possible molecular mechanisms leading to the final morphology of the nylon‐6/clay nanocomposite is discussed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3555–3566, 2005

Collagen orientation patterns in human secondary osteons, quantified in the radial direction by confocal microscopy

The composite structure of secondary osteon lamellae, key micro-mechanical components of human bone, has intrigued researchers for the last 300 years. Scanning confocal microscopy here for the first time systematically quantifies collagen orientations by location within the lamellar thickness. Fully calcified lamellar specimens, extinct or bright in cross-section under circularly polarized light, were gently flattened, and then examined along their thickness direction, the radial direction in the previously embedding osteon. Collagen orientation was measured from confocal image stacks. So-called extinct lamellae and so-called bright lamellae are found to display distinct, characteristic patterns of collagen orientation distribution. Orientations longitudinal to the osteon axis in extinct lamellae, transverse to the osteon axis in bright lamellae, and oblique to the osteon axis in both lamellar types, show parabolic distribution through specimen thickness. Longitudinal collagen in extinct lamellae, and transverse collagen in bright lamellae, peaks at middle third of lamellar thickness, while oblique collagen peaks at outer thirds of both types. Throughout the thickness, longitudinal collagen orientations characterize extinct lamellar specimens, while orientations oblique to the original osteon axis characterize bright lamellar specimens. Measured patterns complement previous indirect results by different methods and reinforce previously hypothesized differences in lamellar mechanical functions.

Genetic diseases affecting the epidermis

Genetic diseases affecting the epidermis

Mutations in lipid transporter ABCA12 in harlequin ichthyosis and functional recovery by corrective gene transfer

Harlequin ichthyosis (HI) is a devastating skin disorder with an unknown underlying cause. Abnormal keratinocyte lamellar granules (LGs) are a hallmark of HI skin. ABCA12 is a member of the ATP-binding cassette transporter family, and members of the ABCA subfamily are known to have closely related functions as lipid transporters. ABCA3 is involved in lipid secretion via LGs from alveolar type II cells, and missense mutations in ABCA12 have been reported to cause lamellar ichthyosis type 2, a milder form of ichthyosis. Therefore, we hypothesized that HI might be caused by mutations that lead to serious ABCA12 defects. We identify 5 distinct ABCA12 mutations, either in a compound heterozygous or homozygous state, in patients from 4 HI families. All the mutations resulted in truncation or deletion of highly conserved regions of ABCA12. Immunoelectron microscopy revealed that ABCA12 localized to LGs in normal epidermal keratinocytes. We confirmed that ABCA12 defects cause congested lipid secretion in cultured HI keratinocytes and succeeded in obtaining the recovery of LG lipid secretion after corrective gene transfer of ABCA12. We concluded that ABCA12 works as an epidermal keratinocyte lipid transporter and that defective ABCA12 results in a loss of the skin lipid barrier, leading to HI. Our findings not only allow DNA-based early prenatal diagnosis but also suggest the possibility of gene therapy for HI.

The microstructure evolution during semisolid molding of a creep-resistant Mg–5Al–2Sr alloy

Analytical electron microscopy, supported by microchemical and microdiffraction techniques, was applied to assess the microstructural changes accompanying semisolid molding of a creep-resistant magnesium alloy with nominal chemistry of Mg–5%Al–2%Sr. In an ingot precursor, the Sr containing precipitates exhibited a morphology of Al 4Sr platelets within eutectic colonies and Al–Mg–Sr films, both residing at grain/cell boundaries, while sub-boundaries were occupied by fine Mg 17Sr 2 plates. Trace quantities of Mg 17Al 12 were present as plate-shaped continuous precipitates within selected grain/cell interiors. Semisolid processing of mechanically comminuted ingots generated thixotropic morphologies with globular solids of α-Mg, having well-developed sub-structures. The quickly-solidified liquid fraction, enriched in Al and Sr, led to the formation of increased volumes of a lamellae type Al 4Sr phase, surrounding the secondary α-Mg. Traces of Mg 17Al 12 still existed, predominantly as irregular shape compounds located mainly in grain interiors. Both the primary solid and high melting point precipitates of Mn–Al modified with Sr, acted as nucleation substrates for secondary α-Mg grains. The possible implications of semisolid processing on the creep behavior of magnesium alloys are discussed.

Sodic amphibole exsolutions in garnet from garnet-peridotite, North Qaidam UHPM belt, NW China: Implications for ultradeep-origin and hydroxyl defects in mantle garnets

Two types of amphibole exsolution lamellae were discovered in garnet from a few garnet peridotites from the North Qaidam ultrahigh-pressure metamorphic belt, northern Tibet, NW China. The amphibole lamellae are strictly oriented in four directions corresponding to the isometric form {111} (i.e., octahedron planes) of garnet. Observations by transmission electron microscopy (TEM) show that amphibole lamellae are topotaxtially concordant with the host garnet and possess 9.8 to 10 Å lattice .c.-spacing. Electron-microprobe analysis reveals that these exsolved amphibole lamellae are high in Na and Ti. The TEM observations and recalculated compositions indicate that the oriented amphibole lamellae exsolved from original supersilicic majorites with high concentrations of Na2O(0.3 wt%) and hydroxyl (up to 1000 ppm by weight). These results imply that the host garnet peridotites were formed at depths greater than 200 km and that garnet can be an important reservoir of water at such depths in the mantle.

A contribution to the study of lamellar armors

The work is based on the finds of lamellar armors from the Early Byzantine site Svetinja at Viminacium. In addition to the analysis of the finds we presented also the analogies from Early Byzantine, Germanic and Avar contexts and we also paid attention to the so far insufficiently known find from Selenca. Along the armors we also analyzed the related lamellar helmets. The work includes discussion of the genesis of lamellar armor types - their Oriental origin and their continuance after the 6th century, i.e. the final years of the 6th and the beginning of the 7th century, when lamellar armors were introduced in the Byzantine army and among Germans and Avars as a result of changes in warfare techniques. Finally, we suggest conclusions resulting from the precisely defined context of the Svetinja find.

Self-organization of nanostructured functional dendrimers

In this article, we review some of our recent work on the development and study of the properties of self-organizing supermolecular liquid crystalline dendritic materials. Prior to this purpose, the state of the art in the field of molecular design, structure and properties of liquid-crystalline dendrimers (LCDs) will be briefly reviewed, and illustrated by a selection of pioneering examples. The first type of LC dendrimer takes into account the location of their functional elements (mesogens) in the periphery of the macromolecules and its topology of attachment, and the nature of the mesogen. We will show how functionality can be in-built into such materials so that self-organising functional systems can be created. Side-chain liquid-crystalline dendrimers exhibiting lamellar, columnar and nematic phases are shown. The mechanism of mesophase formation (mesogen interaction versus microphase separation) is also discussed in relation to the molecular structure (the nature of the mesogen and of the dendritic matrix, dendritic generation number). The second type of LC dendrimer introduced presents a different topology in that the mesogens are now inserted within the dendritic matrix and in the periphery. Owing to their particular constitution, it will be shown that the mesophases of the lamellar and columnar types possess unusual morphologies.

Endoscopic anatomy of the chordae willisii in the superior sagittal sinus

Chordae willisii are structures located in the lumen of the superior sagittal sinus (SSS). It is thought that they act as flow-improving structures within the sinuses. There are few anatomical descriptions of chordae willisii, and all previous observations were performed through standard anatomical dissections. The purpose of this study was to visualize and describe structural and topographical features of the chordae willisii with the aid of rigid endoscopy. Twenty-five SSSs obtained from fresh human cadavers during autopsies were the material for this study. Specimens were flushed with tap water to remove clots. Bridging veins emptying into the sinus were ligated, and continuous flow of a saline solution through the sinus in a physiological direction was achieved by connecting the sinus to an irrigating system. Rigid endoscopes of different diameters (2.7-4.5 mm) and optic (0 and 30 degrees) were inserted into the lumen of the sinus. The endoscope was connected to a digital camera and a video system to allow for recording of the observed structures. Finally, the sinuses were opened and the chordae willisii were dissected using standard anatomical methods. The chordae willisii were observed in all examined specimens. Three different types of the cords were found: lamellar, trabecular, and valvelike types. The most common type was the valvelike (mixed) one, which comprised 45.1% of all cords. The chordae willisii were most commonly observed in the parietooccipital region of the SSS. Witout disturbing any structural relationships, the use of endoscopy allowed visualization and description of intraluminal structures as they behaved physiologically.

Colloidal microstructure of binary systems and model creams stabilized with an alkylpolyglucoside non-ionic emulsifier

The aim of this study was to examine the lyotropic potential of an alkylpolyglucoside mixed emulsifier (Cetearyl glucoside&Cetearyl alcohol), which belongs to the new generation of natural (sugar) surfactants, and to elaborate the potential stabilization mechanism and relation between the colloid microstructure and water distribution within the systems. Polarization and ordinary light as well as transmission electron microscopy, wide and small-angle X-ray diffraction, thermal analysis and rheological measurement were employed for the systems characterization. It was suggested that Cetearyl glucoside&Cetearyl alcohol stabilizes the o/w creams by synergistic effects of viscoelastic hydrophilic gel of lamellar type and lipophilic gel network built up from cetostearyl alcohol semi-hydrates as well as by lamellar liquid crystalline bilayers surrounding the oil droplets. The hydrophilic gel consists of mixed cetearyl glucoside/cetearyl alcohol crystalline bilayers entrapping the water interlamellarly by hydrogen bonding. It is also showed that oil addition into the chosen binary system influences the creams microstructure significantly, which particularly reflects onto the mode of water distribution within the creams and consequently their potential of skin hydration.

Microstructure and hardness studies of the electron beam welded zone of Hastelloy C-276

Electron beam welding (EBW) technique is becoming popular in nuclear, chemical and aerospace industries due to its high penetration depth and fast cooling rate. Samples of Hastelloy C-276 have been welded by electron beam (EB). A scanning electron microscope (SEM) having the attachment of an energy dispersive system (EDS) has been employed to study the resulting microstructure and micro-eutectic phases. The microstructure of the molten zone (MZ) is found to be of fine lamellar type. The hardness of the MZ is found to be 35% higher compared to as-received alloy. The micro-eutectoids are rich in Mo and W. The X-ray diffraction patterns of the MZ show shifting of peaks towards higher angle compared to the diffraction pattern of the as-received alloy. Broadening of the peaks is also observed in the diffraction pattern of the MZ. Formation of the μ-phase was observed in the MZ after a tempering treatment at 950 °C.