Wrapping Materials Research Articles

Use of wood as a wrapper for dry isostatic pressing

The regularities of the process of hard and soft wood pressing are studied in the paper, with the purpose of determining the possibility of using wood as a wrapper for dry isostatic pressing, as it meets the basic wrapper requirements. The advantage of this material is a sufficiently low cost, lack of iron powder adhesion and easy removal after pressing. It is shown that the use of soft wood as the wrapper material allows to obtain products from iron powder mixtures with high density and strength. It is found that the use of additional heat treatment improves the wood pressing, as well as the absence of pressing friction on the matrix walls improves the iron powder compaction. The results of the conducted studies can be used in creating powder products of complex shape, which operate under medium and heavy loads.

Development of a novel scintillation-trigger detector for the MTV experiment using aluminum-metallized film tapes

A new type of a trigger-scintillation counter array designed for the MTV experiment at TRIUMF-ISAC has been developed, which uses aluminum-metallized film tape for wrapping to achieve the required assembling precision of ±0.5mm. The MTV experiment uses a cylindrical drift chamber (CDC) as the main electron-tracking detector. The barrel-type trigger counter is placed inside the CDC to generate a trigger signal using 1mm thick, 300mm long thin plastic scintillation counters. Detection efficiency and light attenuation compared with conventional wrapping materials are studied.

Irradiation performance of PFBR MOX fuel after 112 GWd/t burn-up

The 500MWe Prototype Fast Breeder Reactor (PFBR) which is in advanced stage of construction at Kalpakkam, India, will use mixed oxide (MOX) fuel with a target burnup of 100GWd/t. The fuel pellet is of annular design to enable operation at a peak linear power of 450W/cm with the requirement of minimum duration of pre-conditioning. The performance of the MOX fuel and the D9 clad and wrapper material was assessed through Post Irradiation Examinations (PIE) after test irradiation of 37 fuel pin subassembly in Fast Breeder Test Reactor (FBTR) to a burn-up of 112GWd/t. Fission product distribution, swelling and fuel–clad gap evolution, central hole diameter variation, restructuring, fission gas release and clad wastage due to fuel–clad chemical interaction were evaluated through non-destructive and destructive examinations. The examinations have indicated that the MOX fuel can safely attain the desired target burn-up in PFBR.

Current exposure of 200 pregnant Danish women to phthalates, parabens and phenols

Many phthalates, parabens and phenols are suspected to have endocrine-disrupting properties in humans. They are found in consumer products, including food wrapping, cosmetics and building materials. The foetus is particularly vulnerable and exposure to these chemicals therefore is of concern for pregnant women. We investigated current exposure to several commonly used phthalates, parabens and phenols in healthy, pregnant Danish women. A total of 200 spot urine samples were collected between 8 and 30 weeks of gestation and analysed for metabolites of ten phenols, seven parabens and 16 phthalate by liquid chromatography-tandem mass spectrometry representing 26 non-persistent compounds. The majority of analytes were present in the urine sample collected from most women who participated. Thus, in 174 of the 200 women, metabolites of more than 13 (>50%) of 26 compounds were detected simultaneously. The number of compounds detected per woman (either as the parent compound or its metabolite(s)) ranged from 7 to 21 with a median of 16. The majority of compounds correlated positively with each other within and between chemical groups, suggesting combined exposure sources. Estimated daily intakes (DIs) of phthalates and bisphenol A (BPA) were below their individual tolerable DI (TDI) and with hazard quotients below 1. In conclusion, we found detectable levels of phthalate metabolites, parabens and phenols in almost all pregnant women, suggesting combined multiple exposures. Although the estimated DI of phthalates and BPA for an individual was below TDI, our results still raise concern, as current toxicological risk assessments in humans do not take into account simultaneous exposure. The true cumulative risk for the foetus may therefore be underestimated.

Shelf Life and Quality of Guava cv. Kazi as Affected by Stages of Ripening, Storage Temperature and Wrapping Materials

The experiment was conducted to study the shelf life and quality as affected by different stages of ripening, storage temperature as well as wrapping materials fruits of guava cv. Kazi. All the studied parameters except marketability increased for a certain storage period and then declined due to the effect of stages of ripening and wrapping materials (perforated and non perforated white and black polythene bag), while in case of storage temperature, there was gradual increase of physiological weight loss, sugar content (reducing, non-reducing and total sugar) and TSS content. Marketability decreased markedly with the advancement of storage period. All stages of ripening and all wrapping materials were able to keep fruits in marketable condition for 36 days of storage period. But fruits were in better marketable condition when harvested at stage 3 (ripe, yellowish green in colour and crispy pulp) or wrapped with black non-perforated polythene. 5ºC storage temperature, was able to retain more percentage of fruits in marketable condition with longer storage duration. In case of treatment combinations, fruits harvested at stage 3, stored at 5ºC temperature with black non-perforated polythene had the highest physiological weight loss, sugar content (reducing, non-reducing and total sugar) and TSS content while stage1 fruits stored at 20ºC with no wrapping (control) had the lowest.DOI: http://dx.doi.org/10.3329/pa.v19i2.16906 Progress. Agric. 19(2): 1 - 12, 2008

Materials development for fast reactor applications

Materials play a crucial role in the economic competitiveness of electricity produced from fast reactors. It is necessary to increase the fuel burn-up and design life in order to realize this objective. The burnup is largely limited by the void swelling and creep resistance of the fuel cladding and wrapping materials. India's 500MWe Prototype Fast Breeder Reactor (PFBR) is in advanced stage of construction. The major structural materials chosen for PFBR with MOX fuel are D9 austenitic stainless steel as fuel clad and wrapper material, 316LN austenitic stainless steel for reactor components and piping and modified 9Cr-1Mo steel for steam generator. In order to improve the burnup, titanium, phosphorous and silicon contents in alloy D9 have been optimized for decreased void swelling and increased creep strength and this has led to the development of a modified version of alloy D9 as IFAC-1. Ferritic steels are inherently resistant to void swelling. The disadvantage is their poor creep strength. Creep resistance of 9Cr-ferritic steel has been improved with the dispersion of nano-size yttria to develop oxide dispersion strengthened (ODS) steel clad tube with long-term creep strength, comparable to alloy D9 so as to achieve higher fuel burnup. Improved versions of 316LN stainless steel with nitrogen content of about 0.14wt% having higher creep strength to increase the life of fast reactors and modified 9Cr-1Mo steel with reduced nitrogen content and controlled addition of boron to improve type IV cracking resistance for steam generator application are other developments being perused towards improving the economic competitiveness of fast reactor technology.

High Temperature Materials for Nuclear Fast Fission and Fusion Reactors and Advanced Fossil Power Plants

Development of materials plays a crucial role in the economic feasibility of fast nuclear fission and fusion power plant. In order to meet this objective, one of the methods is to extend the fuel burnup and decreasing doubling time. The burnup is largely limited by the void swelling and creep resistances of the fuel cladding and wrapping materials. India's 500 MWe Prototype Fast Breeder Reactor (PFBR) is in advanced stage of construction. The major structural materials chosen for PFBR with MOX fuel are alloy D9 as fuel clad and wrapper material, 316LN austenitic stainless steel for reactor components and piping and modified 9Cr-1Mo steel for steam generator. In order to improve the burnup further, titanium, phosphorous and silicon contents in alloy D9 have been optimized for better swelling and creep resistances to develop modified version of alloy D9 as IFAC-1. Creep resistance of inherently void swelling resistance 9Cr-ferritic steel has been improved with the dispersion of nano-size yttria to develop oxide dispersion strengthened (ODS) steel clad tube with long- term creep strength, similar to D9, for increasing the fuel burnup. Development of modified 9Cr-1Mo steel clad tube and 9Cr-1Mo steel wrapper for future metallic fuel reactors being developed for reducing the doubling time are in progress. Extensive studies on resistance of this new generation core materials to void swelling are also under progress along with material development. Improved versions of 316LN stainless steel with nitrogen content of about 0.14 wt.% having higher creep strength to increase the life of fast reactor and modified 9Cr-1Mo steel with reduced nitrogen content and controlled addition of boron to improve type IV cracking resistance for steam generator are other developments. India's participation in ITER programme necessitates the development of India-specific RAFM steel for Test Blanket Module (TBM). A comprehensive research programme is being carried out to develop India-specific 9Cr-W-Ta RAFM steel with the optimization of tungsten and tantalum contents for better combination of strength and toughness. Based of the extensive mechanical tests including impact, tensile, creep and fatigue on four heats of RAFM steels having tungsten in the range 1 – 2 wt. % and tantalum in the range 0.06 -.014 wt., the RAFM steel having 1.4 wt. % tungsten with 0.06 wt. % tantalum is found to possess better combination of strength and toughness. This steel is considered as India-specific RAFM steel and TBM is being manufactured by this RAFM steel. To limit the emission of green house gases, a research and development programme has been initiated to develop advanced ultra super critical fossil fuel fired thermal power plants working at temperature of around 973 K and pressure of 300 bar. High temperature creep strength super 304H austenitic steel and Inconel 617 superalloy tubes are indigenously developed for this purpose.

Application of Differential Interference in Electromagnetic Rail Gun Strain Measurement

Strain measurement in electromagnetic rail launching processes is of significant importance to studies on rail life, wrap material selection, and initial armature disturbance. Based on a discussion about the principle of fiber-optic differential strain measurement, the constitution of a rail strain measurement device based on fiber-optic differential interference was introduced, and its data processing method and system calibration method were discussed. With this measurement method, electromagnetic rail strain measurement was completed, and experimental results indicate that the differential strain measurement device is able to operate reliably and stably under an intense electromagnetic interference environment in an electromagnetic railgun launching process and can be applied to strain measurement and in-bore projectile motion velocity measurement of gun barrel weapons.

저장 고춧가루의 색 관련 이화학적 특성과 관능적 특성과의 관계

본 연구는 장기간 저장하는 동안 고춧가루의 품질변화에 대한 물리적 측정치와 시각적으로 인지하는 관능치와의 상관관계를 규명하고자 하였다. 이를 위하여 빛의 투과 여부가 다른 2종류의 포장재 linear low density polyethylene(LLDPE)과 aluminum/linear low density polyethylene(Al/LLDPE)를 선정하여 저장온도와 기간에 따른 수분함량, 색도, ASTA color value, capsanthin 함량 변화를 측정하고고춧가루의 시각으로 인지하는 색과 기호도에 대한 관능검사를 실시하여 비교분석하였다. 고춧가루의 초기 수분 함량은 저장고의 상대 습도에 의해 영향을 받으며 저장고의 온도나 포장재의 재질에 따른 차이는 나타나지 않았다. 색차계로 측정한 L, a, b값 중 적색도를 나타내는 a값은 저장기간이 늘어날수록 감소하였고 황색도를 나타내는 b값은 증가하였다. 두 측정값 모두 저온보다는 고온에서 저장 시 더 많은 영향을 받았으며 포장재의 재질별로 유의적인 차이는 나타나지 않았다. 또한 ASTA color value와 capsanthin 함량은 저장기간이 길어질수록 감소하였고 고온에서 저장 시 더 유의적인 차이가 있었으며 ASTA color value는 빛이 투과하는 LLDPE 재질의 포장재에 저장하였을 경우 더 많이 감소였다. 관능검사 결과 저장 기간이 길어질수록 황색의 강도는 증가하고 매운맛 색과 적색은 감소하여 점차 어두운 적색을 띄며 고온에서 저장 시 더 어두운 적색을 띄는 것으로 평가되었다. 포장재의 재질에 따른 차이는 매운맛 색에 대한 평가에서만 나타났으며 다른 항목에서는 나타나지 않았다. 전체적인 기호도는 적색과 매운맛 색이 감소하고 황색의 강도가 증가할수록 감소하는 것으로 평가되었다. 색소 성분의 물리적 측정치와 관능적 기호도의 상관관계에 대하여 조사한 결과 a값, ASTA color value, capsanthin 함량은 전체적인 외관기호도와 정의 상관관계가 있으며 그중 ASTA color value가 관능적 기호도와 가장 높은 상관관계가 있었다. 따라서 본 연구 결과 고춧가루 저장 시 빛이 통과하지 않는 Al/LLDPE 재질의 포장재에 저장하였을 경우에 품질 변화가 적었고 색소 성분의 물리적 측정치와 관능적 기호도 간에 높은 상관관계가 있는 것으로 나타났으며 고춧가루의 소비자 선호도는 색도계를 이용한 적색도나 ASTA color value, capsanthin 함량에 의해 결정될 수 있다.

A review of shelf-life extension studies of Nigerian indigenous fresh fruits and vegetables in the Nigerian Stored Products Research Institute

The Nigerian Stored Products Research Institute has been conducting research in technology development suitable for post-harvest handling of Nigerian indigenous fruits and vegetables for extension of the shelf-life of these commodities, retention of nutrients and aesthetics of fresh produce in storage, enhancement of the nutritional status and earning capacity of both the rural and urban poor through proper handling, storage, marketing and consumption of fruits and vegetables; and production of the best quality fruits/vegetables for local and export markets over three decades. The research work carried out and the technologies developed for handling of Nigerian indigenous fruits/vegetables post-harvest for the farm, market and domestic levels of storage are discussed subsequently. These indigenous fruits and vegetables are prone to chill injury when kept at low temperatures. However, storage structures developed by the Nigerian Stored Products Research Institute over the years, such as the evaporative coolers and cooler baskets which could record some temperature drop from the ambient, have been used in extending the shelf-life of fresh fruits and vegetables. Packing (wrapping) materials have also showed promise in extending shelf life of Nigerian indigenous fresh produce. The season and time of harvest also play an important role in storage of fruits and vegetables. Garden eggs have very short shelf-life of 7 days during the dry harmattan months in Nigeria. Fresh fluted pumpkin Telfairia occidentalis ‘ugu’ leaves can only be kept for 6 days at 29.1°C and 64.5% relative humidity beyond which physiological breakdown of tissues lead to deterioration and total loss. Fresh pawpaw (Carica papaya L.) fruits, individually wrapped with waxed paper (TIXO) kept at ambient conditions in plastic crate, have a shelf-life of 17 days as compared to fresh pawpaw fruits in evaporative coolers for 7 days. In hot dry weather of the Northern parts of Nigeria, oranges stored in evaporative cooler (EC) Metal-in-Brick wall have a shelf-life of 10 weeks. Adoption of these technologies will play a very vital role in post-harvest loss reduction in fresh fruits and vegetables along the food chain, increase income and improve nutrition for all stakeholders. The interventions to maintain food quality and safety for reduction of postharvest losses in Nigerian indigenous fruits and vegetables through Research activities in NSPRI for three decades are the focus of this review paper. Key words: Postharvest, technologies, fruits, vegetables, shelf-life.

Composite repair of sub-sea pipelines

The development of new deepwater oil and gas fields provide an opportunity for increased use of new materials. Conventional infrastructure is constructed using significant quantities of steel and concrete, which is becoming less practical in comparison to new light weight, easy to handle composites. When infrastructure needs to be repaired, there is often a requirement for underwater welding, which carries considerable occupational health, safety and environment (OHSE) risks. For this reason, moving away from traditional metal structures or repair technologies is increasingly attractive. In recent years a number of new water activated composite wrap materials have been developed for use in underwater applications. The materials properties that are required can be difficult to achieve and maintain over an extended period of exposure to the marine environment, though, so many research groups are working on this challenge. A comprehensive literature review has been undertaken to identify present state of the art ideas for the development of improved underwater materials and this will be discussed in the context of adhesive applications. Preliminary material characterisation work will be described where new resins have been formulated to perform well in marine environments and survive prolonged exposure to seawater. Experiments were carried out in artificial seawater and samples left to cure at a range of temperatures DSC and dynamic mechanical analysis (DMTA) were used to evaluate the crosslink density of the network and the glass transition temperature respectively, while FTIR was used to determine the chemical structure in the cured systems. Preliminary mechanical test results have shown significant improvement in strength for the new formulations compared to a set of control samples of commercially available materials.

A perspective on creep and fatigue issues in sodium cooled fast reactors

Development of advanced materials alongwith improved high temperature mechanical properties, particularly creep and fatigue are important and play a major role for the successful development of robust, safe and economical sodium cooled fast reactor (SFR) technology. The components of SFRs operate in demanding environments at high temperatures under complex creep, fatigue and creep-fatigue loading conditions. Based upon the service requirements in terms of different environments, temperature and loading conditions, different materials are chosen for different components. Ti modified 15Cr-15Ni austenitic stainless steel is chosen for clad and wrapper tubes in the reactor core, which experience high fast neutron flux of ∼ 1015 ncm−2s−1 along with high temperatures. Type 316L(N) SS is used for out-of-core structural components like main and inner vessels, and sodium pipelines. For steam generators, modified 9Cr-1Mo steel is chosen for all the components, where liquid sodium and steam/water coexist. Some of the important experiences and exciting achievements in the areas of in-house materials development and its characterization in terms of creep, low cycle fatigue and creep-fatigue properties important to design of reactor components for core, out-of-core and steam generator applications are described in the paper. Future directions for materials research and development activities involving critical issues like radiation damage resistance along with improved mechanical properties for advanced clad and wrapper materials necessary for achieving high fuel burnup and design life up to 60 years for out-of-core structural components leading to economical nuclear energy have been highlighted.

Abdominal X-ray signs of intra-intestinal drug smuggling

Introduction “Body packers” either swallow or insert drug filled packets rectally or vaginally in order to smuggle illicit drugs. AXR is used routinely to screen suspects for the presence of intra-intestinal drug packages. AXR diagnosis can be difficult as stool or gas within the intestine may resemble ingested foreign bodies. We identify the frequency and co-existence of several signs; tic-tac sign, rosette sign, double condom sign, dense surrounding material, density and discover a new sign; parallelism, which will aid in increasing the radiological accuracy. Methods We retrospectively reviewed 285 AXRs performed for suspicion of drug smuggling during the period of March 2006–March 2009 to identify the frequency of these signs. Results Of the 285 AXRs performed 59 were positive, 221 negative and five were indeterminate. The tic-tac sign was present in 93%, double condom sign in 73%, dense surrounding wrapping material in 36% and parallelism in 27%. Sixty one percentage of drug packages were iso-dense to faeces and 39% hyperdense. Twenty percentage of the positive abdominal radiographs demonstrated one of the radiographic signs, 39% demonstrated two signs, 32% demonstrated three and 7% four. The most common radiographic sign combination was the tic-tac sign with either dense surrounding material or double condom sign. Conclusion The most commonly encountered radiographic sign is the tic-tac sign, followed by the double condom sign and dense surrounding material. We also discover a new sign, “parallelism” which although uncommon is highly specific. Accuracy is further increased by comparing the density of packages to faeces and looking for the co-existence of multiple signs.

Amperometric proton selective sensors utilizing ion transfer reactions across a microhole liquid/gel interface

A new cost-effective amperometric proton selective sensor utilizing a single microhole interface between two immiscible electrolyte solutions (ITIES) is developed. The sensing methodology is based on measuring currents associated with proton transfer across the interface assisted by a proton selective ionophore. The ellipse shaped micro-interface was first fabricated by simple mechanical punching with a sharp needle on a thin PVC film (12 μm thick) commercially available as a food wrapping material. The microhole was then filled up with a gellified polyvinylchloride (PVC)-2-nitrophenyloctylether (NPOE) to create a single microhole liquid/liquid interface. Direct ion transfer reactions across the polarized interface serving as ion sensing platforms were studied using cyclic voltammetry. In order to enhance the selectivity of proton sensing, a proton selective ionophore, octadecyl isonicotinate (ETH1778), was incorporated into the organic gel layer and their electrochemical sensing characteristics were investigated using cyclic voltammetry and differential pulse stripping voltammetry. As an example, we employed the proton selective sensor for the determination of glucose concentrations. The detection scheme involves two steps: (i) protons are first generated by the oxidation of glucose with glucose oxidase in the aqueous phase; and (ii) the current associated with the proton transfer across the interface is then measured for correlating the concentration of glucose.

Split defect and secondary fermentation in Swiss-type cheeses – A review

Split and secondary fermentation defects in Swiss-type cheese varieties are manifested as undesirable slits or cracks that may lead to downgrading of the cheese. Split defect is associated with an excessive production of gas or an unsuitable cheese body that cannot accommodate gas produced, or a combination of both factors. Secondary fermentation is the apparent production of gas after the desired propionic fermentation of the warm room has taken place. No consensus exists as to the definitive causes of the defects, but possible causes are reviewed under factors that are associated with rheological behaviour (including cheese manufacture, acidification, intact protein content and proteolysis, seasonality of milk supply and ripening or storage temperature and duration) or with overproduction of gas (including milk microflora, propionic acid bacteria (PAB) — in particular strains with high aspartase activity and ability to grow at low temperatures, lactic acid bacteria, interactions between starter bacteria, facultatively heterofermentative lactobacilli (FHL) and other sources of gas including butyric acid fermentation). The influence of other parameters such as copper concentration, air incorporation, salt content, rind formation and cheese wrapping materials is also considered. Methods to reduce the prevalence of the split defect and secondary fermentation include addition of water to improve elastic properties by the removal of unfermented carbohydrate and the use of FHL to control PAB activity to prevent the production of excessive gas.

Fossil evidence for the origin of spider spinnerets, and a proposed arachnid order

Silk production from opisthosomal glands is a defining characteristic of spiders (Araneae). Silk emerges from spigots (modified setae) borne on spinnerets (modified appendages). Spigots from Attercopus fimbriunguis, from Middle Devonian (386 Ma) strata of Gilboa, New York, were described in 1989 as evidence for the oldest spider and the first use of silk by animals. Slightly younger (374 Ma) material from South Mountain, New York, conspecific with A. fimbriunguis, includes spigots and other evidence that elucidate the evolution of early Araneae and the origin of spider silk. No known Attercopus spigots, including the original specimen, occur on true spinnerets but are arranged along the edges of plates. Spinnerets originated from biramous appendages of opisthosomal somites 4 and 5; although present in Limulus, no other arachnids have opisthosomal appendage homologues on these segments. The spigot arrangement in Attercopus shows a primitive state before the reexpression of the dormant genetic mechanism that gave rise to spinnerets in later spiders. Enigmatic flagellar structures originally described as Arachnida incertae sedis, are shown to be Attercopus anal flagella, as found in Permarachne, also originally described as a spider. An arachnid order, Uraraneida, is erected for a plesion, including these two genera, based on this combination of characters. The inability of Uraraneida precisely to control silk weaving suggests its original use as a wrapping, lining, or homing material.

Stiffness- and Conformation-Dependent Polymer Wrapping onto Single-Walled Carbon Nanotubes

This work reports the effect of stiffness and conformation of chain-like polymers on wrapping behaviors around single-walled carbon nanotubes (SWNT). As a model of chain-like polymers, three kinds of poly(dialkylsilane) (PSi)s with random-coiled, flexible, and semiflexible main chains were employed. Complexes of PSi and SWNT were prepared using mechanochemical high-speed vibration milling (HSVM). Stiffness-dependent polymer wrapping behaviors were investigated using combinational analyses with a differential scanning calorimeter, transmission electron microscopy, and atomic force microscopy. Furthermore, the conformational behaviors of the PSi's wrapped onto SWNTs were characterized spectroscopically with ordinary UV spectroscopy. Random-coiled and flexible PSi's were successfully wrapped onto small bundles of SWNTs, in which their conformations were changed to fit the surface curvatures of the SWNTs. However, semiflexible PSi could not form a complex with SWNTs, and its conformation remained unchanged even after the same HSVM process. Knowledge gained from this study may lead to a new approach to molecular design of chain-like polymers for efficient wrapping materials for SWNTs.

The Use of Autogenous Sclera as Wrapping Material in Hydroxyapatite Implantation

Purpose: To report postoperative results and effectiveness using autogenous sclera as a wrapping material for hydroxyapatite orbital implant. Methods: A chart review of 78 patients (78 eyes) undergoing primary enucleation or a secondary procedure using autogenous sclera as a wrapping material from March 1997 to October 2004 was undertaken. Primary enucleation was performed in 54 eyes and secondary implantation in 24. In severely constricted eyes or eviscerated eyes with small implants, the sclera was unfolded and used for wrapping only on the anterior surface of the implant. Results: The average size of implants was 19.7 mm in diameter, and all the 78 implants were over 18 mm. During an average postoperative follow-up of 18 months, complications such as implant exposure, infection or extrusion did not occur in any case. Conclusion: This study shows that autogenous sclera is a safe, effective wrapping material for hydroxyapatite orbital implants with no serious complications.

Fossil evidence for the origin of spider spinnerets

AbstractSilk production from opisthosomal glands is a defining characteristic of spiders (Araneae). Silk emerges from spigots (modified setae) borne on spinnerets (modified appendages). Spigots from Attercopus fimbriunguis (Shear, Selden & Rolfe, 1987^1^), from Middle Devonian (386 Ma) strata of Gilboa, New York were described in 1989^2^ as evidence for the oldest spider and the first use of silk by animals. Slightly younger (374 Ma) material from South Mountain, New York, conspecific with A. fimbriunguis, includes spigots and other evidence which elucidate the evolution of early Araneae and the origin of spider silk. No known Attercopus spigots, including the original specimen^2^, occur on true spinnerets but are arranged along the edges of plates. Spinnerets originated from biramous appendages of opisthosomal somites 4 and 5; while present in Limulus, no other arachnids have opisthosomal appendage homologues on these segments. The spigot arrangement in Attercopus shows a primitive state prior to the re-expression of the dormant genetic mechanism which gave rise to spinnerets in later spiders. The inability of Attercopus precisely to control silk weaving suggests its original use as a wrapping, lining or homing material.

French and United Kingdom Experience of High-Burnup Mixed-Oxide Fuel in Sodium-Cooled Fast Breeder Reactors

From the 1960s to the end of the 20th century, considerable studies were performed in Europe on fast breeder reactor fuels for reaching an industrial maturity. In the European plan, the European fast reactor project reached in 1998 the phase of validation of the concept, satisfying the requirements of economy and safety of the countries that contributed to the project.In this paper, we intend to give an idea about the main obstacles met on the way toward the high burnups: inner corrosion cladding interface, swelling and mechanical behavior of the constitutive materials (clad and wrapper), pin/pin interactions and pin/wrapper mechanical interactions, wrapper interactions within the reactor core, etc.For this, the paper is divided in three parts:1. fuels, with an emphasis on the oxide of U and Pu that constitutes the reference in Europe for reaching high burnups2. cladding and wrapper materials: austenitic stabilized steels and ferritic-martensitic steels, but also the Nimonic alloy favored in the United Kingdom3. behavior of the subassembly not only in a normal operating situation but during its complete life cycle: transport, in-pile handling, and earthquake resistance.In conclusion, we define the points of optimization to reach the Generation IV reactors objectives: cladding material (multistabilized austenitic steel grades and oxide dispersion strengthened developments) solutions allowing one to limit the inner clad corrosion, check the potential of alternative fuels such as carbide and nitride, and study the possibilities of including minor actinides for their transmutation.