Fine Silk Research Articles

Relative toxicity ofnC24 agricultural mineral oil toTetranychus urticaeKoch (Acari: Tetranychidae) andPhytoseiulus persimilisAthias-Henriot (Acari: Phytoseiidae) and its possible relationship to egg ultrastructure

The relative toxicity (LC50 values based on µg oil/cm2) is evaluated of aqueous nC24 agricultural mineral oil (AMO) emulsions to the egg, six-legged nymph (larva), eight-legged protonymph and adult stages of two-spotted mite (Tetranychus urticae) and its predator, Phytoseiulus persimilis, on French bean leaf discs, using a Potter spray tower to apply of the oil. The egg of P. persimilis was the least susceptible stage (LC50 444.84) and its LC50 was significantly higher than all other stages tested of either P. persimilis or T. urticae. The LC50 for adult female T. urticae (LC50 63.89) was significantly lower than the larva (LC50 93.86); however, there was no significant difference in response between the protonymph (LC50 70.44) and the larva, which were both higher than T. urticae eggs (LC50 17.55). LC50s for P. persimilis larva (LC50 43.87), protonymph (LC50 41.55) and adult female (LC50 53.34) were similar. Scanning electron microscopy showed that the egg surface of T. urticae is usually well covered with fine silk that may trap more oil and increase AMO efficacy. Other possible differences in AMO efficacy between T. urticae and P. persimilis may be due to differences in egg size, egg incubation period, egg surface structure and the presence of vulnerable respiratory cones in T. urticae eggs. Dose of 0.2–0.3% (w/w) is considered to be the most appropriate for nC24 AMOs use against T. urticae in combination with P. persimilis in integrated pest management programs.

A new modification of transanal Swenson pull-through procedure for Hirschsprungʼs disease

The one-stage pull-through procedures for Hirschsprung's disease (HD) have become popular because it is well accepted by surgeons and mothers with no visible scar and a short hospital stay. It represents the latest development in the concept of a minimally invasive surgery for HD. We introduce a new method of transanal one-stage pull-through for Hirschsprung's disease, different from the transanal Soave procedure.One hundred and thirty-four patients aged 9 days to 5 years underwent a transanal one-stage pull-through procedure. The diagnosis was definite by barium enema or rectal biopsies preoperatively. The patients were anesthetized and placed in the lithotomy position. A urinary catheter was optional. Giving anorectal dilatations for half a minute, a pull-through of the rectum above the peritoneal reflection and into the intussusception was performed. Fine silk suturing was performed circumferentially at the level of that point which was used for traction for the distal end. Another circumferential suture was performed parallel 0.5 cm distance above the original one and used for traction for the proximal intestines. The full-thickness rectal wall was truncated between the above two circumferential sutures with cautery. The proximal intestines were pulled down and the mesenteric vessels were dissected with ligation until normal intestines were accessed; the presence of ganglion cells was determined by intraoperative rapid frozen section. The distal end was dissected anteriorly 2.5- 3.5 cm above the dentate line. The posterior rectal wall was split longitudinally and dissected to a point 0.5- 1.0 cm above the dentate line. The segment of the lesion was resected. The length of bowel resected ranged from 12 to 50 cm (median 16.5 cm). An oblique anastomosis was made.The mean operating time was 70 minutes. Postoperative rectal dilation was not required. The patient tolerated feeding on the first postoperative day. Eighty-eight patients were followed-up. All these patients had 2- 3 bowel movements per day at postoperative month 1. They were discharged within 4.5 days after the operation. Six patients presented with complications. All recovered by reoperation or conservative treatments.The modification of the transanal Swenson pull-through procedure for Hirschsprung's Disease is an easy adaptation to a well-established technique and has a reasonable result.

The First Danish Deep-Sea Expedition on the Ingolf: 1895 and 1896

The Danish Ingolf Expedition took place in the summer months of 1895 and 1896, with C. F. Wandel as captain, a man with long experience in hydrographical work in the Arctic. The other scientific participants were the zoologists H. Jungersen, W. Lundbeck and H. J. Hansen during the 1895 cruise; C. Wesenberg-Lund replaced Hansen during the 1896 cruise. C. H. Ostenfeld was the botanist and M. Knudsen the hydrographer. The Ingolf (see Figure 1) was a naval cruiser. In both years the voyages were hindered by ice that had moved much further south than normal, even closing most of the Denmark Strait. In 1895, the best results were obtained south of Iceland and in the Davis Strait; in 1896 south and east of Iceland and as far north as Jan Mayen Island. A total of 144 stations were completed, all with soundings, trawlings and (for the first time) continuous hydrographical work associated with the deep-sea trawling (bottom measurements of temperature, salinity, chlorine contents and specific gravity). Eighty of the stations were deeper than 1,000 m. There were more than 800 hydrographical measurements, with about 3,300 registrations recordings added on the basis of the measurements. 138 gas analyses were performed on board with samples from the surface and the sea bottom. The main result of the expedition was the final demonstration of probably the most important threshold boundaries in the world: the Wyville Thompson Ridge from East Greenland to Scotland with maximum depths of 600 m, separating the fauna in the Norwegian and Polar Sea to the north, always with negative below-zero temperatures except close to the Norwegian coast, from the fundamentally different general Atlantic deep-sea fauna to the south of the ridge with positive temperatures. The results are published in the Ingolf Report, with fifteen volumes containing forty-three papers by nineteen Danish authors and fourteen papers by six foreign authors. The sieving technique was excellent—due to an apparatus designed by H. J. Hansen that kept the animals under water until preservation and using the finest silk for sieving. In this way, the expedition collected more smaller animals than had been acquired by previous deep-sea expeditions. Hansen's studies of the peracarid crustaceans and parasitic copepods and Lundbeck's report on the sponges were particularly noteworthy. The 130 photographs taken on board and on land by the ship's doctor William Thulstrup represent a cultural/historical treasure.

Adhesive efficiency of spider prey capture threads

Cribellar capture threads are comprised of thousands of fine silk fibrils that are produced by the spigots of a spider's cribellum spinning plate and are supported by larger interior axial fibers. This study examined factors that constrain the stickiness of cribellar threads spun by members of the orb-weaving family Uloboridae in the Deinopoidea clade and compared the material efficiency of these threads with that of viscous capture threads produced by members of their sister clade, the Araneoidea. An independent contrast analysis confirmed the direct relationship between cribellar spigot number and cribellar thread stickiness. A model based on this relationship showed that cribellar thread stickiness is achieved at a rapidly decreasing material efficiency, as measured in terms of stickiness per spigot. Another limitation of cribellar thread was documented when the threads of two uloborid species were measured with contact plates of four widths. Unlike that of viscous threads, the stickiness of cribellar threads did not increase as plate width increased, indicating that only narrow bands along the edges of thread contact contributed to their stickiness. As thread volume increased, the gross material efficiency of cribellar threads decreased much more rapidly than that of viscous threads. However, cribellar threads achieved their stickiness at a much greater gross material efficiency than did viscous threads, making it more challenging to explain the transition from deinopoid to araneoid orb-webs.

An Australian webspinner species makes the finest known insect silk fibers

Aposthonia gurneyi, an Australian webspinner species, is a primitive insect that constructs and lives in a silken tunnel which screens it from the attentions of predators. The insect spins silk threads from many tiny spines on its forelegs to weave a filmy sheet. We found that the webspinner silk fibers have a mean diameter of only 65 nm, an order of magnitude smaller than any previously reported insect silk. The purpose of such fine silk may be to reduce the metabolic cost of building the extensive tunnels. At the molecular level, the A. gurneyi silk has a predominantly beta-sheet protein structure. The most abundant clone in a cDNA library produced from the webspinner silk glands encoded a protein with extensive glycine–serine repeat regions. The GSGSGS repeat motif of the A. gurneyi silk protein is similar to the well-known GAGAGS repeat motif found in the heavy fibroin of silkworm silk, which also has beta-sheet structure. As the webspinner silk gene is unrelated to the silk gene of the phylogenetically distant silkworm, this is a striking example of convergent evolution.

Structural characteristics and properties of Bombyx mori silk fiber obtained by different artificial forcibly silking speeds

To study the spinning condition of natural biopolymer silk, the silk fibers were directly acquired from Bombyx mori silkworm, N140 × C140 by a simple artificial forcibly silking method at the speed of 60, 120, 180 and 240 cm min −1, respectively and its microstructure and physical properties were evaluated. The fine silk fibers (about 8 μm) were obtained at faster spinning speed, 240 cm min −1. The tensile properties of silk fibers were remarkably increased with raising the forcibly spinning speeds. The β-sheet structure contents of silk fibers obtained at higher speed were considerably increased. The fibers obtained by different spinning speeds exhibited a fairly similar X-ray crystallinity, while the degree of molecular orientation increased with decreasing the fiber diameter. The fine silk fibers obtained at higher speed (240 cm min −1) exhibited a slightly higher thermal stability, as shown by the upward shift of differential scanning calorimetry (DSC) decomposition temperature.

Karl Grimes: Dignified Kings Play Chess on Fine Green Silk, Sherra Murphy, Gallery of Photography, National Museum, Dublin, September - November 2007

Karl Grimes: Dignified Kings Play Chess on Fine Green Silk, Sherra Murphy, Gallery of Photography, National Museum, Dublin, September - November 2007

Column: General Topics

DuPont first introduced microfibers in 1989. Microfibers have diameters that are less than typical fibers. They are half the diameter of fine silk fiber, one quarter the diameter of fine wool, and one hundred times finer than human hair. Denier, the weight in grams of a 9000-meter length of a fiber, is the term used to define the diameter or fineness of a fiber. While the definition for the thickness of microfibers is varied, a common definition is that microfibers are 0.9 denier or less. For comparison, the nylon stocking is knit from 10-15 denier fiber.

AFM studies of swift heavy ion and electron irradiated mixed barium strontium borate nonlinear optical crystal

Single crystals of novel nonlinear optical material of mixed barium strontium borate is grown in our laboratory by employing the low-temperature solution technique. Equal proportion (1:1 molar ratio) of AR grade barium borate and strontium borate are mixed together in double distilled water to prepare a supersaturated solution. The solution is allowed to evaporate at constant temperature (30°C) in a Petri dish for about a week which resulted in the formation of seed crystals. These seed crystals are used to grow larger crystals by suspending them using fine silk thread in the supersaturated mother solution. The solution is allowed to evaporate at constant temperature. This resulted in the growth of good transparent crystals of dimension 15 mm×10 mm×1 mm after about one month. These crystals show good second harmonic generation (SHG) efficiency. The mixed barium strontium borate crystal is found to be a promising nonlinear optical crystal, which possibly can be used for fabrication of photonic devices. The single crystals of mixed barium strontium borate are irradiated by 120 MeV Ag +13 swift heavy ions (SHI) of fluence 5×10 11 ions/ cm 2 at Nuclear Science Centre, New Delhi and also by electrons of 8 MeV energy with a fluence 5.7×10 9/cm 2 using Microtron accelerator at Mangalore University. Surface morphology studies of these crystals are carried out using atomic force microscope. The AFM topographical images of these SHI/electron irradiated single crystals of mixed barium strontium borate are obtained from different frames of the sample taken at different magnifications using atomic force microscope. An attempt is made to explain the surface damage caused due to SHI/electron irradiation using the observed AFM images.

Direct synthesis of hydroxyapatite-silk fibroin nano-composite sol via a mechanochemical route

In the presence of fine silk cocoon (silk fibroin, SF) powder, a low viscosity sol of nano-hydroxyapatite (HAp, Ca10(PO4)6(OH)2)—SF was synthesized by a wet mechanochemical reaction. Nano crystals of HAp are oriented along their c-axis. The secondary structure of SF was changed by milling. A uniform thin gel film was obtained by a simple dip coating on the glass substrate precoated by chitosan.

Asteroid hyalosis

…when suddenly, you realize that time has filled your eyes with threads of fine silk, wandering like seaweeds in a dead water pond, and with refringent grains of black sand, floating at all times between you and your landscapes.

Fiberoptic Intracranial Pressure Monitoring during Magnetic Resonance Imaging

Fiberoptic Intracranial Pressure Monitoring during Magnetic Resonance Imaging

Structure and dyeability of Bombyx mori silk fibers with different filament sizes

This study deals with the analysis of structure, physical properties, and dyeing behavior of silk fibers with different filament sizes. Fine and coarse silk fibers were obtained from Akebono and Ariake cocoon varieties, respectively. Both samples exhibited a fairly similar x-ray crystallinity, while the degree of molecular orientation increased with decreasing the fiber size. Tensile strength and energy of fine silk fibers were significantly higher, while elongation at break did not change in relation to the fiber size. Fine silk fibers exhibited a slightly higher thermal stability, as shown by the upward shift of both the DSC decomposition temperature and the TMA final extension step at above 300°C. The TGA and DMA (E″) patterns remained unchanged regardless of fiber size. The amino acid analysis confirmed the absence of any difference of chemical structure between fine and coarse silk fibers, the content of acidic, basic, and other characteristic amino acid residues being exactly the same. Accordingly, both samples adsorbed the same amount of hydrochloric acid. Ex-haustion dyeing tests with various direct, acid, and reactive dyes showed the occurrence of appreciable differences in the perceived color between fine and coarse silk fibers. The size of color difference was quantitatively evaluated by reflectance measurements and discussed in relation to silk fiber morphology, structure, as well as dyeing conditions. The kinetics of diffusion of two model dyes was not significantly affected by the different fiber size and structure. © 1996 John Wiley & Sons, Inc.

What forces are responsible for the stickiness of spider cribellar threads?

AbstractThe surface of spider cribellar prey capture thread is formed of thousands of fine silk fibrils. The stickiness of this thread is often attributed to the ability of these fibrils to catch on irregular surfaces. However, 14‐month‐old cribellar threads of Hyptiotes cavatus (Uloboridae) were significantly less sticky than freshly spun threads. Slight changes in cribellar thread dimensions failed to fully explain this reduced stickiness, demonstrating that an auxiliary force contributes to the stickiness of cribellar threads. Because this force does not appear to rely on the snagging of fibrils, it may enhance the ability of cribellar threads to hold prey with smooth surfaces. © 1993 Wiley‐Liss, Inc.

The pattern of axonal degeneration in the peripheral nervous system varies with different types of lesion

Degeneration of axons in the mouse sciatic nerve was examined using conventional silver staining and by noting the presence or absence of a compound action potential on stimulating the nerve distal to the point of crush or cut. The presence of myeloperoxidase-positive cells was also examined in frozen sections of the nerve. In all experiments the distal, disconnected segment was studied. Degeneration after crushing with fine watchmakers forceps always began in the most distal part of the nerve and proceeded in a distoproximal direction, from the nerve entry point into a muscle back to the crush site. Myeloperoxidase-positive cells were also recruited into the nerve starting at the distal rather than proximal (the originally injured) end. This result favours the view that degeneration is triggered by lack of trophic support from the cell body rather than entry of deleterious substances at the site of the injury, for the terminals furthest from both the source of supply and the injury are affected first. Degeneration following nerve section was always more rapid than after crushing. The rate of axonal sealing at the injury was, however, no slower than after crushing, so it does not seem likely that greater entry of possible degeneration-triggering material at the injury site is the explanation for this. Crush lesions in which the perineurium was also cut open and the blood supply at the site was damaged, degenerated at the slower rate characteristic of simple crushes. Hence, it does not seem likely that perineurial or vascular damage, both of which are much more extensive following nerve section, provide an explanation for the more rapid degeneration of cut nerves. If a sufficiently large length of sciatic was frozen or if it was ligatured with fine silk, degeneration was as rapid as after nerve section, while, if a ligature was immediately untied, degeneration was as slow as that following crush with forceps. It is concluded that continuing contact of the distal with the proximal nerve stump slows degeneration, possibly by allowing Schwann cells above and below the lesion to continue communicating or by providing a minimal supply of trophic material.

An afterloading technique suitable for the oral cavity and oropharynx and capable of adaptation for use with remote afterloading units.

Implantation of carcinomas of the tongue with radium 226 or its substitutes is a highly successful method of treatment (Paterson, 1963). The commonly used techniques have two disadvantages: first, they are not truly afterloading, and secondly, none of them is easily applied to tumours of the base of tongue. The loop technique described by Henschke et al (1963) is difficult to use in this area mainly because of the problems associated with afterloading the radioactive wire. A non-looping technique for interstitial implants of the base of tongue has been described by Vikram and Hilaris (1981), which is dependent on the fact that polyethylene softens when soaked in saline solution and can be punctured by fine needles to secure the “crossing” catheter with fine silk. However, this method is not satisfactory with the nylon tubes commonly used in the UK. The technique described below is simple and can easily be adapted for use with remote afterloading machines, using either iridium 192 or caesium 137.

The intraneural distribution of myelinated fibres in the equine recurrent laryngeal nerve.

The intraneural course of nerve fibres in the equine recurrent laryngeal nerve was investigated by partially ligating the nerve at a proximal site, and 3-8 weeks later, tracing the course and spatial relationships of intact and degenerating fibres along the distal stump. This nerve was chosen because of its great length, the fact that it is a nonbranching motor nerve and because of debate about the course of abductor and adductor nerve fibres in the recurrent laryngeal nerve. Six ponies were used and in each the recurrent nerve was partially ligatured about 20 cm from the larynx, using a fine silk suture. In all there was a clear separation of intact and degenerating fibres just distal to the suture, but they became mixed close to the point of innervation of the laryngeal muscles. The numbers of intact myelinated fibres remained similar along the partially denervated nerve segment. These results suggest that myelinated fibres mix within the recurrent laryngeal nerve and that focal lesions of this nerve should not result in denervation of individual laryngeal muscles.

Marcação individual de triatomíneos para estudos comportamentais e ecologicos

Idealizou-se uma técnica de marcação de insetos adultos, visando principalmente à identificação individual de triatomineos, que consiste na elaboração de códigos correspondentes a números, através de cinco cores basicas (vermelho, branco, azul, verde e amarelo) representadas por pintas coloridas feitas com tinta esmalte e depositadas do pronoto ao escutelo do inseto manualmente, com um fino pincel de seda. As pintas não devem se estender às asas sobrepostas, porque estas mudam constantemente de posição, encobrindo assim a marcação. A tinta é indelével e, por não apresentar toxicidade, não afeta a longevidade e o comportamento dos insetos. A técnica pode ser utilizada tanto para insetos no laboratório quanto no campo principalmente em trabalhos relacionados à Ecologia e ao Comportamento.

Coevolutionary Race Continues: Butterfly Larval Adaptation to Plant Trichomes

Plant trichomes can act as efjective defenses against herbivores, but at least one species of ithomiid butterfly, Mechanitis isthmia, has evolved a unique adaptation for avoiding the trichomes on its spiny Solanum hosts. The larvae are gregarious all together they spin a fine silk scaffolding over the tops of the spines on which they can crawl and feed in safety.

A technic for repeated bile collections from an intact enterohepatic circulation.

Enzymatic (1) and gas chromatographic technics (2) for the quantification of bile acids developed in the past 10 years, have resulted in the publication of vast data on the composition of bile. Almost without exception, bile for these studies has been obtained under nonphysiologic conditions, e.g., single sampling of duodenal bile from fasting humans, collections from tubes in the common duct proximal to the sphincter of Oddi, or from chronic fistula preparations. However, interruption of the enterohepatic circulation changes the composition of bile (1), concentrations of the constituents of bile vary with sampling technics (2), and the volume, total solutes and percentage concentration of constituents vary throughout a 24-hr period (3). We have modified technics, first used by Dragstedt et al. (4) and later by Preshaw and Grossman (5), in studies of pancreatic secretion to develop a canine preparation which allows repeated sampling of bile from an intact enterohepatic circulation. Figure 1 is a diagrammatical representation of the method we have used to construct a duodenal pouch containing the intact sphincter of Oddi, draining through a Gregory cannula (6) into the duodenum opposite a Thomas cannula (7) in the reconstituted duodenum and extending through the abdominal wall. Surgical technic. The upper abdomen is opened through a right paramedian incision. Vessels between the duodenum and the pancreas are carefully ligated with fine silk to mobilize a segment of duodenum 1.5 cm distal and proximal to the point of entry of the common duct. After ligation of the accessory pancreatic duct the duodenum is transected at points 1 cm and 3 cm proximal to the main pancreatic duct. The Gregory cannula is passed through the antemesenteric wall of the duodenal segment and proximal and distal ends of the pouch are closed in 2 layers.