Shell Perforation Research Articles

Pointed bone tools from the Hamangia culture on the Lower Danube: Manufacture and function

This study focuses on the pointed bone tools from the Hamangia culture (Chalcolithic period, late 6th millennium BC - early 5th millennium BC), obtained from the long bones of caprines by quadri-partition with double grooving. The pointed bone tool assemblage from the Hamangia settlement at Cheia-Vatra Satului (Romania) was selected as a case study for analysing technological manufacturing sequences of these specific typological tools. Our study was two-fold: 1. identifying the sequence of the procedures in the chaîne opératoire from the original bone to the finished pointed tool; 2. determining the functionality of these tools (as multipurpose items or designed for a single activity only). For the purposes of this research, we focused on the diagnostic pieces such as preforms, blanks, and manufacturing waste, rather than the finished pieces, in an attempt to reconstruct the entire sequence of the manufacturing procedures, to visualize their transformation from the bone to the finished object. This experimental approach resulted in detailed records of the raw material used, the time necessary for each type of procedure, the tools used, and the results obtained during each operation. Next, the experimental tools were tested in various scenarios, such as hide perforation, bone breaking, shell perforation, wood processing, vegetable fiber production, etc. The active ends of these items were then observed, with variables such as frequency and distribution of polish, micro-topography, pattern of functional striations, presence of microfractures, and use-wear areas. The observations made on the archaeological specimens were compared to those on the experimental replicas in order to test the hypotheses regarding the ways the pointed tools were manufactured and used by the prehistoric communities.

A Numerical Study on Projectile Penetration into Underwater Torpedo Warhead

Underwater torpedo interception could be conducted by shell perforation or even warhead impact detonation with high speed projectiles. This work deals with the projectile water entry and sequent penetration into underwater torpedo whereby both aluminium shell perforation and explosive detonation are numerically studied. The water entry model and aluminum impact model are validated against test data for underwater aluminum shell penetration. Targets are located under water with 20 cm depth where aluminium shells for penetration are air-back while the impact detonation model has explosives inside shell. Four kinds of different nose shape tungsten projectiles are used for penetration simulation, revealing that ogival nose projectiles have superior performance for both shell perforation as well as detonation than conical nose projectiles. Numerical predictions shed some light on nose shape optimization design of high velocity projectile against torpedoes.

Air-Backed Aluminum Shells Subjected to Underwater Penetration: Torpedo Interception Simulations

Underwater torpedoes have become a serious threat to ocean liners and warships, and the interception against attacking torpedoes is always the hotspot in marine engineering. To simulate the underwater torpedo interception by a high velocity projectile, this work numerically deals with the process of projectile water entry and sequent penetration into underwater aluminum shells, whereby conical and ogival nose projectiles are comparatively studied. With the arbitrary Lagrange–Euler (ALE) algorithm adopted to describe fluid medium, the projectile water entry model is developed and validated against the test data. Similarly, the penetration model validation is made by modeling a tungsten ball perforation on an aluminum plate. Covered by water fluid, the air-backed aluminum shell is utilized to simulate an underwater torpedo subjected to projectile impact. The numerical predictions of underwater penetration reveal that ogival nose projectiles have a superior performance in underwater motion and perforation while conical nose counterparts deteriorate the shell targets more severely. For 20 cm, 40 cm and 60 cm underwater depth scenarios, a numerical prediction suggests that the energy consumed by water is proportional to the water depth, meanwhile aluminum shell perforation absorbs almost the identical projectile kinetic energy. Such findings may shed some light on the nose shape optimization design of high velocity projectile intercepting underwater torpedoes.

Solutrean personal ornaments: identification of a new process of shell perforation at Lachaud (Terrasson, Dordogne, France)

Solutrean personal ornaments: identification of a new process of shell perforation at Lachaud (Terrasson, Dordogne, France)

Physiological responses of broiler embryos to in ovo implantation of temperature transponders1, 2

Previous techniques that have been used to monitor broiler embryonic temperature and metabolism during incubation either have been invasive to the embryo or have not directly determined internal egg temperature. Therefore, the current investigation was conducted to determine the earliest day of incubation on which temperature transponder implantation in the egg air cell could be performed with minimal invasiveness to broiler embryogenesis. Eggs from young broiler breeder hens (Ross 308; 27 wk of age) were weighed and set on 3 tray levels (approximately 120 eggs per tray level) of a single incubator. Randomly, on each tray level and on each day between d 10 and 14 of incubation, 4 embryonated eggs were assigned to an invasive control (IC) treatment (shell perforation only) and 4 other embryonated eggs were assigned to a transponder implantation (TI) treatment (shell perforation, followed by transponder implantation in the air cell). Four embryonated eggs per tray were also assigned to a noninvasive control treatment on d 10 of incubation. Percentage of embryo survivability through d 18 of incubation, and percentages of mean daily incubational egg weight loss between d 18 and each respective day of implantation were calculated. Furthermore, various internal organ and tissue parameters were examined on d 18 of incubation. Embryo survivability was reduced because of transponder implantation on d 10 and 11 of incubation; however, embryo survivability was not different between eggs in the noninvasive control and IC treatments and the eggs that received the TI treatment on d 12, 13, and 14 of incubation. In comparison with eggs in the IC treatment, those in the TI treatment had a higher percentage of embryo weight. Conversely, yolk sac moisture was significantly higher in IC-treated eggs than in TI-treated eggs. It was concluded that temperature transponders may be inserted into the air cells of broiler hatching eggs between d 12 and 14 of incubation without adversely affecting eggshell porosity or embryogenesis and without causing physiological stress to growing broiler embryos.

A new generation inflow performance modelling tool with improved capabilities

The inflow performance prediction of a completion is one of the most important tasks in forecasting production performance of a well. When selecting an optimum completion design it is essential to compare different options and perform parametric studies, one of the key completion decisions being the selection of a cased and perforated or barefoot well. In cased and perforated wells, key inflow performance parameters include gun type, perforation penetration depth, shot density, shot phasing, depth of mud invasion and dependence of their effects on reservoir properties. The open literature hosts a plethora of inflow equations for some classic completion practices; however, complex options are not adequately addressed. More importantly, when one compares inflow performance of various completion options or conducts a parametric study of certain parameters, the relative calculation results do not always make sense. In this paper, we describe an operator’s (Shell International Exploration and Production) in-house study to develop a consistent set of inflow performance equations that not only make sense in their own right, but also make good relative sense when comparing different completion options, particularly with regard to cased and perforated wells. Most of the significant open literature has been reviewed and a set of consistent inflow models have been compiled and developed. Many equations have been improved—e.g., perforation skin calculations, mechanical and total skin calculations, rate dependant skin for horizontal completions—and new equations have been derived for options not previously modelled in the literature (e.g., barefoot and perforated completions, double perforated completions, re-perforated completions and complex horizontal completions). All equations have been coded into the Shell Perforation Optimisation Tool (SPOTTM) software package, enabling engineers to easily and accurately predict and compare complex completion options for design decisions. Inflow performance calculation results of various completion scenarios and parametric studies are also presented.

Post-capture hyperbaric simulations to study the mechanism of shell regeneration of the deep-sea hydrothermal vent mussel Bathymodiolus azoricus (Bivalvia: Mytilidae)

This study describes the influence of hydrostatic pressure (HP) on regeneration of the artificially perforated shell in the vent mytilid Bathymodiolus azoricus. Pressure-dependent and size-dependent shell repair mechanism and haemocyte response was detected following post-capture hyperbaric simulations at environmentally relevant pressures at 1, 85, 175 and 230 bars as compared to control situation, i.e. prior to shell perforation. We provide evidence for the following: (1) shell wound repair is influenced by both hydrostatic pressure and depositional substrate: newly forming crystals emerge 10 days after induction, but only in animals maintained under HP similar to their site of provenience, in spite of the fact that B. azoricus is known to be euribarofilic as indicated by its biomass-dominance at various sites along a bathymetric gradient; shell repair also commenced at 1 bar, but only when the regeneration substrate was periostracum; (2) wound recovery, i.e. closure of the shell notch in B. azoricus is slower than in non-vent bivalves, i.e. it was not completed in 120 days at 1 bar; (3) shell repair involves the Ca bearing haemocytes, referred here as granulocytes, but this may not be automatically considered as the mechanism for (non-induced) shell calcification; blood cell counts showed that the raise in haemocyte number, where statistically significant, was reversible to pre-induction levels by day 10, which may indicate immune response rather than an active calcification process; (4) blood cells of the freshly collected animals contained bacteria resembling sulphur oxidiser endosymbionts from the gill, which may have profound immunological implications, and may be considered as an additional mechanism for environmental transmission of symbiosis.

EPIPUNCTAE AND PHOSPHATIZED SETAE IN LATE ORDOVICIAN PLAESIOMYID BRACHIOPODS FROM ANTICOSTI ISLAND, EASTERN CANADA

Epipunctae, a new type of shell perforation, are well developed in typical taxa of the family Plaesiomyidae, a group of common orthide brachiopods from Laurentia and some other tropically located tectonic plates of Late Ordovician age. These minute, prominently elongate, tubular structures are similar to endopunctae in size and density, but differ in being oblique, intersecting the shell surface at a relatively low angle, and being confined largely to the outer portion of the shell wall. The tubules are similar in orientation to aditicules within the same shells but are much smaller and denser, usually aligned along fine growth lines and arranged in crude longitudinal columns. Exceptionally preserved phosphatic molds of bundled setal canals inside epipunctae and aditicules, described for the first time in this paper, are direct evidence that these two types of tubular structures of different sizes had the same function of housing sensory setae along the shell margin, but both the setae and the tubules became abandoned in the outer portion of the shell wall through burial by the secondary shell layer when the shell margin migrated forward. Epipunctae have been found so far only in plaesiomyid shells, but aditicules are common in many groups of the order Orthida. The taxonomic value of epipunctae is shown by a reassessment of PionorthisSchuchert and Cooper, 1932. The hypotype previously regarded widely, but erroneously, as the archetype of ‘Orthis sola’ Billings, 1866, the type species of Pionorthis, is allied to PlaesiomysHall and Clarke, 1892. It bears the characteristic epipunctae. The holotype of Orthis sola is a dalmanelloid shell with true punctae, assignable to MendacellaCooper, 1930. This warrants rejection of the genus Pionorthis.

Bedload abrasion and the in situ fragmentation of bivalve shells

AbstractThe aim of this study was to determine how Unio bivalve shells fragment within the channel of the Sakmara River (southern Urals, Russia). The Sakmara River has an abundant bivalve population and a highly variable flow regime which, at low flow, allowed much of the channel bed to be examined. A large data set of 1013 shells (Unio sp.) was examined and these were shown to have consistent patterns of orientation, aspect, shell abrasion, perforation and fracture. The close spatial relationship between areas of shell abrasion, shell perforation and shell fracture showed that they form part of a continuum whereby areas of abrasion evolve into perforations and perforations coalesce and enlarge into fractures. The mechanism of shell damage proposed is one of abrasion in place, whereby the shell remains stationary on the surface of the point bar and is impacted by bedload. Underpinning this process are the hydrodynamic properties of the bivalve shell, with consistency in the orientation and aspect of the valve in a flowing current producing consistency in the distribution of damage on the shell surface. Valves preferentially lie in a convex‐up position and orientate in the flow such that the umbo faces upstream. The elevated, upstream‐facing umbo region is exposed to particle impact and is the first to be abraded and perforated. The vulnerability of the umbo to perforation is greatly increased by the thinness of the shell at the umbo cavity. The in situ abrasion process is enhanced by the development of an armoured gravel bed which restricts valve mobility and maintains shells within the abrasion zone at the sediment–water interface. The in situ abrasion process shows that broken shells are not a reliable indicator of long distance transport. The study also raises the issue that tumbling barrel experiments, which are generally used to simulate shell abrasion, will not replicate the type of directionally focused sand‐blasting which appears to be the principal cause of shell fragmentation in the Sakmara River.

Predation of late Marjuman (Cambrian) linguliformean brachiopods from the Deadwood Formation of South Dakota, USA

One hundred and twenty-five linguliformean brachiopods of late Marjuman (Cambrian) age with shell perforations, presumably caused by predation, were recovered from shallow-water limestones at two localities of the Deadwood Formation in the Black Hills of South Dakota, USA. Three-quarters of the perforated valves belonged to taxa in the order Acrotretida, while one-quarter of the specimens belonged to those of the order Lingulida. This is the first report of predation of fossil lingulids. In both orders there was a marked selection for valve type. Ninety-five per cent of all perforations of acrotretids were in the ventral valve, while 87% of all perforations of lingulids were in the dorsal valve. The highest rate of predation of collected acrotretids, at any stratigraphic horizon, was 22%, while the rate of predation of collected lingulids, at any given stratigraphic horizon, was as high as 9%. Half of the perforated valves had round holes with a sharp, non-beveled exterior edge, and half had irregularly shaped holes with chipped interior edges. The former type is attributed to either boring or a swift, piercing percussive strike, while the latter is attributed to a smashing percussive strike with a blunt appendage. A third type of perforation consisting of minute, roughly circular holes is thought to be too small to be the work of predators, and is assumed to be the result of an encrusting organism or parasite. The different types of perforation seen in the brachiopod valves indicate that there was more than one type of predator attacking them, including possibly one of the earliest durophages. Various hypothetical predators are suggested as potential candidates for causing the shell perforations. The criteria for their selection as possible linguliformean predators include possessing the ability to produce one of the two types of shell perforation, and being small enough to warrant preying on small (< 2 mm) brachiopods.

A new method for fixing Biomphalaria glabrata for histologic studies, using shell perforation.

A new technique for fixation of Biomphalaria glabrata for histologic studies is described. It consists in performing several external holes in the shell, before placing the entire snail into the fixative. It is a very practical and quick procedure that showed excellent results when compared to the usual techniques.

An In Vitro Study of the Effect of In-Folds on the Durability of Mammary Implants

We hypothesize that the presence of in-folding in a filled mammary shell leads to shortening of the time to failure under tensile fatigue. Specimens, cut from pristine shells, were mounted in S-folded, creased, and unfolded configurations. A characteristic change, occurring in a transmembrane capacitance-proportional alternating current (AC) signal, which was used to monitor working of each specimen, was chosen as a robust marker that preceded frank shell perforation. Subjecting all specimens to stringent, controlled conditions led to time-to-fatigue failure estimates that demonstrated an order-of-magnitude reduction in lifetime for the folded specimens when compared with that for pair-matched, unfolded specimens. Creases also reduced the fatigue lifetime, but not to the degree that folds did. Observations based on the experimental behavior of folded shell material provide possible mechanisms for the potential lifetime clinical reduction of in-folded implants as well as for the development of silicone-on-silicone abrasive wear and generation of debris.

Patterns of shell penetration by Chorus giganteus juveniles (Gastropoda: Muricidae) on the mussel Semimytilus algosus.

Patterns are described for shell penetration by the sublittoral muricid snail Chorus giganteus during predatory attacks on the mussel Semimytilus algosus. Location, form and size of shell penetrations were observed in relation to the size of the predator. The results suggested that positions of the perforations on the mussel shells were related to size of the attacking snail. Smaller snails perforated areas near the shell ligament and in the central zone of the shell, while larger snails more frequently attacked shell borders, principally on the ventral side. These observations may be related to: (a) changes in the process of manipulation of the prey during development of the foot and the shell tooth of the predator, (b) changes in internal structure of the snails related to the shell perforation mechanism, or (c) learned behavior acquired experientially by the snails during early growth. Although in other studies of muricid penetration patterns larger boreholes made in shells of the prey were positively correlated with increasing predator size, this relation did not appear to hold with C. giganteus, as larger specimens often made relatively small shell perforations. Areas of boreholes made in the mussel shells by this snail varied from 0.01 to 1.1 mm(2), and were unusually variable in size and shape, especially when compared with literature results on bores characteristic of other muricid species.

L-3,4-Dihydroxyphenylalanine ( l-DOPA) secreted by oyster ( Crassostrea gigas) mantle cells: functional aspects

l-DOPA is present in many molluscan periostraca and is thought to play an important role in the shell protein sclerotization mechanism. We analyzed l-DOPA content in organic membranes produced by the oyster ( Crassostrea gigas) mantle as a reaction against shell damage, such as induced by Polydora sp. infestation, an artificial perforation of the shell, and in normal oysters mantle. When oysters are secreting the protective organic membrane against a shell perforation, the area of mantle close to the repairing region had a greater l-DOPA content than the remaining mantle. Mantle border as a whole had the same l-DOPA content as the central mantle. Nevertheless there is a variation pattern in mantle border l-DOPA content, the area near the umbo having a higher content and decreasing towards the frontal region. l-DOPA content in younger oysters was greater than that in older oysters. The results of perforation experiment suggest a good correlation between organic membrane synthesis and l-DOPA mantle border content. Concerning normal oysters, a higher l-DOPA content in mantle border than in central mantle would be expected but we couldn’t detect any differences. From all the results there is some evidence that mantle l-DOPA is related to other functions in addition to participating in the sclerotization mechanism.

Bleeding of pulmonate snails

A technique for removing blood (haemolymph) by syringe from African land snails (Achatina spp.) is described. The method avoids the need for shell perforation or incision of soft tissues and appears to have few adverse effects on the snail.

A Five-year Study of the Effects of the Walnut Aphid and the European Red Mite on Persian Walnut Productivity in Coastal Orchards12

A five-year study of the effects of the walnut aphid, Chromaphis juglandicola (Kaltenbach), and the European red mite, Panotlychus ulmi (Koch), was conducted in a coastal Persian walnut, juglans regia L., orchard in California. By using four 4×4 Latin squares of single tree plots, selective pesticide regimes controlled or permitted aphid or mite populations that developed annually for 3 years, after which both species were controlled on all trees for 2 years. Yield reductions by aphids averaged 25% over the 1st 3 years, and continued at 28 and 43% during the 4th and 5th years after control was reestablished. Mite infestations had no effect on yield until the 3rd year when there was a 40% loss; losses of 22 and 31% persisted after control was reestablished. The symptom of effects upon the tree which proved to be the most sensitive to infestation by aphids or mites proved to be loss of productivity of staminate flowers (catkins). The effect on staminate flowers would be the most likely to reveal a damage threshold of such populations. After the 2nd and 3rd year of infestation, there was an average reduction in number of staminate flowers (catkins) of 68% attributable to aphids, 61% to mites, and 85% when both species were present. Aphid infestation reduced walnut size and increased shriveling of kernels, perforation of shells, and adhering hulls. European red mite had no effect upon nut quality. This experiment demonstrated that severe long-term effects by leafcell sucking arthropods on orchard tree productivity extend at least 2 years and probably much longer after return to control of infestation through chemical intervention.

Perforations-A Prime Source of Well Performance Problems

As sure as technology comes up with a nifty solution to a persistent problem you can bet it will have to come up with equally nifty solutions problem you can bet it will have to come up with equally nifty solutions to the new problems caused by he original solution. This is called progress. progress. Introduction This investigation was undertaken to determine the cause of difficulties encountered in injecting fluids through perforations into unconsolidated permeable Pliocene and Miocene sand reservoirs. The particular Pliocene and Miocene sand reservoirs. The particular wells in question are in the South Pass Block 24 and Block 27 fields, located at the mouth of the Mississippi River. We felt that injectivity impairment, by preventing proper placement of sand-control, was a primary cause of the high incidence of sand-control primary cause of the high incidence of sand-control failure and associated casing damage. We expected that by understanding the source of injectivity impairment we could also obtain a better insight into the cause of productivity impairment common to those wells. Impairment of injectivity into unconsolidated sands can be a serious problem since a essential part of the completion is the injection of sand-consolidating fluids into the formation through the perforations, or the deposition of gravel in the perforation tunnels (the holes through the casing and cement sheath). Portions of an interval not accepting consolidating Portions of an interval not accepting consolidating chemicals would be subject to early sand-control failure. Treatment through impaired perforations could cause the impairment to become "locked in place" by the treatment plastics and result in seriously decreased well productivity. In gravel packing, the perforation tunnels must be filled with properly sized perforation tunnels must be filled with properly sized gravel to prevent the tunnels from becoming filled with fine formation sand when the well is put on production. Perforation tunnels filled with fine production. Perforation tunnels filled with fine formation sand severely restrict fluid flow. The tunnels can most likely be filled with gravel only if fluid can flow out of the wellbore through the perforation tunnels and carry gravel into them during perforation tunnels and carry gravel into them during gravel-packing operations. Perforation Flow Impairment Perforation Flow Impairment There has been widespread evidence of a severe perforation flow impairment problem in Shell's perforation flow impairment problem in Shell's Delta Div. in South Louisiana. Plastic consolidation fluids usually could not be pumped outward through the perforations without acid stimulation or fracturing, neither of which has assured uniform placement throughout the perforated interval. Gravel-packed wells have commonly required acidizing before full-depth-allowable production could be obtained. Recovered gravel-pack production could be obtained. Recovered gravel-pack screens and blast joints have frequently shown only one or two eroded holes (Fig. 1), suggesting that most of the produced fluid was coming from only a few of the perforations. Steps were taken, therefore, to isolate the cause of impairment of well injectivity and productivity. A process of elimination was begun in the field concurrently with laboratory investigations. The extent of perforation impairment and its relative importance with perforation impairment and its relative importance with respect to other possible sources of trouble (drilling mud or cement or completion fluid) were studied individually. Drilling mud and cement were considered to be possible contributors to impairment primarily because possible contributors to impairment primarily because of the way dispersant-type filtrates affect the clay material in the formation. P. 399