Plastic Rod Research Articles

SP-SAT: DEVELOPMENT OF AN EDUCATIONAL SATELLITE

n Bolivia, as in several other Latin American nations, there is a growing trend of burgeoning space projects and a rising interest among young students in the aerospace domain. Consequently, there arises an imperative to cultivate a new generation of space professionals. However, the exorbitant costs associated with the equipment utilized in these projects render them inaccessible to a vast majority of inter- ested students, including CubeSat kits, educational satellites, satellite kits, among others. Consequently, alternatives like educational sat- ellites have emerged to simulate the satellite design, construction, testing, launch, and operation processes on a scale conducive to student involvement. The primary challenge faced by students lies in integrating the essential subsystems of a satellite, encompassing power supply, sensors, and communication systems, within the confines of limited space. Considering this, the design and construction of an educational satellite with its respective signal reception equipment was developed. The equipment designed and manufactured is a low-cost one so that universities and educational centers could acquire it. This equipment educational kit is called SP-SAT (Space Program — educational satellite kit). This real satellite simulator offers a wide variety of educational activities. The kit’s equipment is distributed in two systems: 1) Space Segment, which consists of an Onboard Computer (OBC), Electrical Power System (EPS), Communications System (COMM), Experiment Plate (PYL), Complete PLA plastic structure (3D printed), rods, bolts, and nuts. 2) Ground segment: This segment includes all the equipment that is part of the ground station, which will receive data from the satellite.

Hydraulic investigation of flow and bed load transport in diverging compound channels with rigid and flexible vegetation

Floodplains are really important for the environment as they provide various functions for waterways, including ecological, hydrological, and geomorphic ones. During overbank flows, there are complex hydrodynamic conditions that occur as water interacts with the rough floodplain vegetation and drag forces due to the vegetation that changes the flow pattern. However, we still don't fully understand how floodplain vegetation influences channel-altering hydrodynamic forces and sediment transport. To address this, we conducted flume experiments and measured flow pattern and sediment transport under varied floodplain geometry and rigid and flexible conditions. For this purpose, a physical model was constructed in the laboratory, in which plastic rods with a diameter of 10 mm will be used as trees, and artificial grass will be grass vegetation. Thus, 36 experiments were conducted in which the sedimentation and hydraulic parameters of the flow were calculated by measuring the flow velocity, water surface, and sediment transport rate. The results show that in the floodplain with dense (rigid and flexible) vegetation, the friction coefficient (f) is even 1.5 times higher than in the floodplain without vegetation. The parameters such as flow velocity, bed shear stress and Darcy Weissbach friction coefficient increase in the vertical plane between the main channel and floodplains due to the difference in roughness between the main channel and floodplains. In addition, in the main channel, the flow resistance is almost constant and does not depend on the vegetation density. The Darcy-Weissbach friction coefficient is greatly increased in the presence of grass and tree vegetation on the floodplain, and the larger contribution of f is due to the grass vegetation. The results also showed the sediment transport rate has a direct relationship with the angle of divergence and density of vegetation and an inverse relationship with the relative depth of the flow. Therefore, as the sediment transport rate decreases in the diverging compound channel, the wavelength and height of the dunes increase. At smaller divergence angles, the dunes tend to the top of the zero line (the level of the sediments before the formation of the bed form). In the presence of vegetation, due to the increase in the roughness ratio of the floodplain to the main channel, the contribution of the main channel to the flow rate increases. As a result, the sediment transport rate increases.

Compressive behavior of triaxially braided metal-CFRP hybrid lattice structures

Cellular approaches facilitate the flexible design of materials with desirable properties that may be manufactured from single polymers, metals, and, recently, fiber-reinforced composites. This paper describes cellular materials with metal and carbon fiber-reinforced plastic (CFRP) struts. Composite lattice tubular structures were automatically braided, and the effects of axial CFRP yarns on the compressive behaviors of braided lattices were studied. Metal wire-reinforced plastic and metal rods served as axial yarns when preparing hybrid triaxially braided metal-CFRP lattices. The effects of the axial yarns in polyurethane (PU) foam-filled samples were also assessed. Ten braided structures were manufactured, and their compressive behavior and energy absorption were evaluated by axial compression tests. Finite element (FE) simulations were used to investigate deformation, buckling, and damage. Addition of axial CFRP yarns improved the compressive properties; the specific absorbed energy (SAE) increased by 16%. Hybridization further enhanced the SAE by 62%.

Bioinspired Whisker Sensor for 3D Mapping of Underground Mining Environments.

Traversing through challenging, unstructured environments, particularly in mining scenarios characterized by dust concentration, darkness, and lack of communication presents formidable obstacles for traditional sensing technologies. Drawing inspiration from naked mole rats, characterized as being skilled subterranean navigators that depend heavily on touch to navigate their environment, this study introduces a new whisker-sensing disk designed for 3D mapping in unstructured environments. The disk comprises a circular array of 32 whisker sensors, each featuring a slender flexible plastic rod attached to a compliant base housing a 3D Hall-effect sensor. The whisker sensor is modeled using both analytical and data-driven approaches to predict rotation angles based on magnetic field measurements. The validation and comparison of both models are performed by evaluating data from other whisker sensors. Additionally, a series of experiments demonstrates the whisker disk's capability in performing 3D-mapping tasks, along with successful implementation on diverse robotic platforms, highlighting its future potential for effective 3D mapping in complex and unstructured subterranean environments.

Liquefaction behaviour of aluminium and plastic rod assemblies using bi-axial apparatus with application of image analysis

It has recently been shown that the overall deformation characteristics of granular materials during liquefaction seems to be governed by local void ratio characteristics. The aim of this study is to investigate the relationship between mechanical properties and local void ratio changes during liquefaction in two materials of different weights (aluminium-type and plastic-type rod assemblies). A series of constant-volume cyclic bi-axial loading tests was conducted together with the image analysis obtaining local void behaviour. The experimental results demonstrate that the first liquefaction resistance of the plastic sample is higher than the aluminium one, corresponding to its smaller initial void ratio and less contractive behaviour observed in the early stage of drained monotonic compression. However, after experiencing the first liquefaction and subsequent re-consolidation histories, a liquefiable assembly of aluminium and plastic rods both became either denser (densification) or more homogenous (homogenization) in terms of local void ratio, suggesting an increase in liquefaction resistance in the next liquefaction stage. This work also includes a preliminary analogous study using a semi-3D discrete element method (DEM) with one single layer of spherical particles to simulate the similar liquefaction behaviour observed in the laboratory tests.

Inducing Pseudopregnancy in Female Mice Without the Need for Vasectomized Males Prior to Non-Surgical Embryo Transfer or Artificial Insemination.

For successfully maintaining pregnancy with embryo transfer or artificial insemination,female recipient mice must be induced into a pseudopregnant state. Female mice are traditionally paired overnight with vasectomized males, and the following morning, the presence of a copulation plug is assessed. To increase the efficiency of producing pseudopregnant females, a cervical manipulation technique has been standardized to be used in combination with non-surgical embryo transfer or artificial insemination techniques in mice. The blunt end of a small plastic rod is inserted vaginally to contact the cervix and is vibrated for 30 s by contact with a trimmer. The procedure is quick and does not require anesthesia or analgesia. This technique increases the reliability and predictability of producing pseudopregnant females and entirely eliminates the requirement for vasectomized males. For CD1 mice, the efficiency of pseudopregnancy induction using cervical manipulation was 83% for females in estrus (N = 76) but only 38% of females in estrus were plugged by vasectomized males (N = 24). Artificial insemination in CD1 mice was performed by estrus synchronization with hormones, cervical manipulation, and the uterine transfer of sperm. Artificial insemination recipients receiving cervical manipulation (N = 76) had a pregnancy rate of 72% and an average litter size of 8.3 pups. This method can also be used to produce pseudopregnant females for non-surgical embryo transfer. Therefore, inducing pseudopregnancy by cervical manipulation is a convenient and efficient alternative to mating with a vasectomized male when performing non-surgical assisted reproduction techniques. Using cervical manipulation provides 3Rs (replacement, reduction, and refinement) benefits for assisted reproduction techniques by reducing the number of animals required and eliminating the necessity for surgically altered males.

Гидродинамика сетных жестких безузловых конструкций

Rigid netting structures are elements, parts of commercial fishing gear and aquaculture cages. They serve to enclose or filter hydrobionts, they are engineering structures. Rigid netting structures can be used as inserts in commercial fishing gear, as well as selective gratings and elements that prevent hydraulic backwater in trawls. They are also elements of stationary fishing gear, such as winders or other fishing gear or barriers. In aquaculture cages, rigid netting structures, the elements of which have a sufficiently large value of the longitudinal and transverse modulus of elasticity E, are parts that ensure the strength of the netting structures. Mesh rigid structures are made of plastic or aluminum rods in the form of cylinders, which can be either smooth or twisted. The article considers the application of a numerical method for determining the hydrodynamic characteristics of mesh rigid structures using the software developed by the authors. A schematization of a rigid netting structure, a mathematical model based on Navier-Stokes partial differential equations, a computational domain, initial and boundary conditions are proposed. The calculation was carried out on a regular computational grid using an implicit finite-difference scheme using the methods of coordinate-wise splitting, linearization of nonlinear equations with subsequent correction of nonlinear coefficients, and solution of the obtained tridiagonal systems by the sweep method. The results of numerical experiments are presented in the form of visualization of pressure on the surface of various mesh structures at various angles of attack.

Experimentation and Numerical Modeling of Peak Temperature in the Weld Joint during Rotary Friction Welding of Dissimilar Plastic Rods.

Rotary friction welding (RFW) could result in lower welding temperature, energy consumption, or environmental effects as compared with fusion welding processes. RFW is a green manufacturing technology with little environmental pollution in the field of joining methods. Thus, RFW is widely employed to manufacture green products. In general, the welding quality of welded parts, such as tensile strength, bending strength, and surface hardness is affected by the peak temperature in the weld joint during the RFW of dissimilar plastic rods. However, hitherto little is known about the domain knowledge of RFW of acrylonitrile butadiene styrene (ABS) and polycarbonate (PC) polymer rods. To prevent random efforts and energy consumption, a green method to predict the peak temperature in the weld joint of dissimilar RFW of ABS and PC rods was proposed. The main objective of this work is to investigate the peak temperature in the weld joint during the RFW using COMSOL multiphysics software for establishing an empirical technical database of RFW of dissimilar polymer rods under different rotational speeds. The main findings include that the peak temperature affecting the mechanical properties of RFW of PC and ABS can be determined by the simulation model proposed in this work. The average error of predicting the peak temperature using COMSOL software for five different rotational speeds is about 15 °C. The mesh element count of 875,688 is the optimal number of meshes for predicting peak temperature in the weld joint. The bending strength of the welded part (y) using peak welding temperature (x) can be predicted by the equation of y = -0.019 x2 + 5.081x - 200.75 with a correlation coefficient of 0.8857. The average shore A surface hardness, impact energy, and bending strength of the welded parts were found to be increased with increasing the rotational speed of RFW.

Mechanical Performance and Microstructural Evolution of Rotary Friction Welding of Acrylonitrile Butadiene Styrene and Polycarbonate Rods.

Rotary friction welding (RFW) is a green manufacturing technology with environmental pollution in the field of joining methods. In practice, the welding quality of the friction-welded parts was affected by the peak temperature in the weld joint during the RFW of dissimilar plastic rods. In industry, polycarbonate (PC) and acrylonitrile butadiene styrene (ABS) are two commonly used plastics in consumer products. In this study, the COMSOL multiphysics software was employed to estimate the peak temperature in the weld joint during the RFW of PC and ABS rods. After RFW, the mechanical performance and microstructural evolution of friction-welded parts were investigated experimentally. The average Shore A surface hardness, flexural strength, and impact energy are directly proportional to the rotation speed of the RFW. The quality of RFW is excellent, since the welding strength in the weld joint is better than that of the ABS base materials. The fracture occurs in the ABS rods since their brittleness is higher than that of the PC rods. The average percentage error of predicting the peak temperature using COMSOL software using a mesh element count of 875,688 for five different rotation speeds is about 16.6%. The differential scanning calorimetry curve for the friction-welded parts welded at a rotation speed of 1350 rpm shows an endothermic peak between 400 to 440 °C and an exothermic peak between 600 to 700 °C, showing that the friction-welded parts have better mechanical properties.

MP09-20 CONTRAST AGENTS FOR UROLOGIC FLUOROSCOPY: A COMPARATIVE PHANTOM STUDY

You have accessJournal of UrologyCME1 Apr 2023MP09-20 CONTRAST AGENTS FOR UROLOGIC FLUOROSCOPY: A COMPARATIVE PHANTOM STUDY Anahita Heshmat, Gene Austin, Manuel Arreola, and Benjamin Canales Anahita HeshmatAnahita Heshmat More articles by this author , Gene AustinGene Austin More articles by this author , Manuel ArreolaManuel Arreola More articles by this author , and Benjamin CanalesBenjamin Canales More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003224.20AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: The recent international shortage of iodinated contrast agents has driven many clinicians to search for alternative agents to image a variety of urologic conditions in order to maintain clinic workflow. We sought to standardize these agents by a quantitative comparison using a phantom model. METHODS: A donut shape gel phantom with 10-mm wide plastic rods filled with Omnipaque-300, Omnipaque-350, Visipaque-270, Isovue-370, Gadavist, Eovist, and liquid water, was used to represent a patient being imaged for an urethrogram study utilizing a mobile fluoroscopy. The phantom was imaged with various acquisitions (Auto tube voltage (kVp), tube current (mA), and various dose modes, frame rates, and magnification modes) to compare and asses image quality for different contrast agents. Quantitative evaluations were performed with extracting regions of interest (ROIs) of each contrast rod to gather mean pixel values and standard deviations. These ROI measurements were then utilized to calculate contrast-to-noise ratio (CNR) as the metric appropriate for image quality evaluation. RESULTS: The mean pixel and CNR values of Omnipaque-300, Omnipaque-350, Visipaque-270, Isovue-370, and Gadavist showed no difference in visibility among these five contrast agents while using different dose modes, frame rates, and magnification modes. However, that was not the case for Eovist as its mean pixel value and CNR value were close to those of liquid water. Furthermore, changing magnification from normal to magnification 1 and magnification 2 increased the mean pixel values and CNR values at normal dose and continuous frame rate. CONCLUSIONS: With the exception of Eovist, the iodinated and gadolinium-based contrast agents we tested can be interchanged without compromising visibility or image quality based upon this comparative phantom study. Source of Funding: None © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e113 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Anahita Heshmat More articles by this author Gene Austin More articles by this author Manuel Arreola More articles by this author Benjamin Canales More articles by this author Expand All Advertisement PDF downloadLoading ...

New insights into Maxwell’s equations based on new experimental discoveries

No theory is absolute as scientific exploration is the product of human ingenuity, which will continue to evolve with the development of new discoveries and technology.It has been established that the electric field is produced by friction, and the changing electric field can be then generated by constant friction. After the friction stops, this electrostatic field will exist for a designated period of time or even longer. Accordingly, a series of experiments were designed to test the proposed Collision Electro–Magnetic Theory (CEMT) that the electromagnetic energy can be generated by the collision. The 1-W bulb can be lighted by collecting the changing electric field energy when a polymethyl methacrylate (PMMA) board was rubbed with polytetrafluoroethylene (PTFE) film by hand. When a closed coil was placed in the changing electric field, an induced current and an induced electromotive force were generated in the coil, which also magnetized the scissors in the coil. The 1-W bulb can produce a current by the generated changing electric field, when one end of the plastic rods was rubbed by fur.In addition, we discovered that shaking the plastic rod with an electrostatic field generated by the friction can also generate a changing electric field, which not only wirelessly lighted the 28-W fluorescent tube lamp, but also produced an induced current and an induced electromotive force in the closed coil nearby the lamp.Based on the above experiments, we have the following speculation: just as the unified theory of electromagnetism suggests, the changing electric field produces a magnetic field, and the varying magnetic field produces an electric field. Stated plainly, the electric field is in fact a magnetic field and the magnetic field is also an electric field, so they can be both be regarded as energy fields in essence. The coil and conductor can be regarded as the energy collector that can collect energy from the energy field, as long as there is a constantly changing energy field in the collector. The conduction current is transmitted in the collector, while part of the energy field that is not collected in free space, which corresponds to the displacement current calculated in the fourth equation of Maxwell's equations.The essence of Maxwell's equations and related laws are two different phenomena resulting from an energy field in the closed-loop self-circulating state or open-loop acyclic state. The first equation describes an open-loop static energy field, and the second equation describes a closed-loop static energy field. The third equation describes how the induced conduction current can be generated in the closed-loop energy field, and the fourth equation describes how the induced conduction current can be generated in the open-loop energy field.Based on the new experimental discoveries, this work interprets Faraday's law of electromagnetic induction, Maxwell's displacement current and Maxwell's equations from a new perspective, which is important to understand the nature of Maxwell's equations systematically.

A new method of gamma level gauge using a position-sensitive sensor with rod plastic scintillator

Radiometric measuring has many applications, and nucleonic level measurement is one of them. The traditional level gauge works for detecting the level in the tank according to the changes of radiation amount due to the changes of the level in liquid or solid materials. In this study, we proposed a new method of level gauging with some significant advantages for the continuous level meter. In our experimental job, we used a plastic scintillation rod detector and tried to detect the time difference between two photomultiplier tubes to define the approximate point of radiation exposure to the detector. Results show that our innovative method has some clear advantages when compared to the traditional level measurement. This position-sensitive detector succeeded in improving the method of calibration. Also, this method is independent of the type and activity of the radioactive source. Furthermore, this new method helps reduce the source activity, so from viewpoint of health and environmental issues, our method has a lot of benefits. This method has another significant result, and we succeeded in improving the accuracy of the level measurement ten times better than traditional level measurement.

Plastic rod as a promising feed material for enhanced performance of ultrasonic plasticization microinjection molding: Plasticization rate, mechanical and thermal properties

A polymer plasticization rate measurement method is proposed for ultrasonic plasticization microinjection molding. The effect of ultrasonic amplitude on the plasticization rate of polypropylene (PP) rods was comprehensively investigated, and the mechanical and thermal properties of PP rods were studied using tensile tests, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Results show that the plasticization rate of PP rods increased from 67.25 mg/s to 192.41 mg/s with increase of ultrasonic amplitude, an increase of 186%. The mechanical properties of the PP samples remained stable under different ultrasonic amplitudes, with tensile strength around 21 MPa and elongation at break about 21%. DSC and TGA results showed that PP samples exhibit improved thermal properties after ultrasonic plasticization compared with pure PP. The melting point of the PP sample decreased from 171.7 °C to 164.0 °C and the crystallinity increased from 26.1% to 38.7%. The temperatures corresponding to 1% and 5% weight loss of PP increased from 283.63 °C to 350.30 °C without ultrasonic amplitude to 393.70 °C and 420.13 °C, respectively. The studies have great significance to further understand the influence of ultrasonic plasticization process parameters on the plasticization rate and material properties of polymers.

The polarity of a plastic rod and a glass rod at contact charging

This study aims to determine the polarity of a plastic rod and a glass rod at contact charging with various materials. Contact charging often occurs when two electrically neutral materials are brought into contact, and then separated. Thus, selecting the types of material pairs has a critical role to make the contact charging more observable and measurable. This study was designed to address the astonishment of students who accidentally learned that a plastic rod can be positively charged at contact charging. What materials can cause the plastic rod to become positively charged at contact charging? This is the main research question of this study. Thus, we searched the polarity of a plastic rod and a glass rod at contact charging with various materials by using a typical laboratory electroscope and also a modern electronic electroscope. At the end of the study, it was shown that although the plastic rod is generally negatively charged at contact charging with many materials, it is positively charged at contact charging with a nylon garbage bag, a piece of nitric, or a piece of Teflon (PTFE). In addition, the glass rod is generally positively charged at contact charging with many materials except the human hair.

Understanding Failure analysis using harmonic analysis and empirical mode decomposition techniques

The investigation pertains to the failure analysis of Fibre Reinforced Plastic rods used in overhead transmission line insulators using appropriate data acquisition and analysis. The leakage current data, over an experimental period is captured and time–frequency analysis is implemented for determining the in-service condition of the overhead transmission insulators. It is observed from the investigation that the signal displays various events like dry-band arcing, partial surface arcs and triple-point discharges at the electrodes. The study presents a simple time–frequency analysis used for presenting the phenomena, an algorithm is developed for the harmonic analysis, also Empirical Mode Decomposition is conducted to reinforce the analysis. The main focus of the study is to estimate the early failures with minimal time and with available data.

Failure Mechanism Analysis of Bonded Joint with Fiber Reinforce Plastic (FRP) Sucker Rod in Offshore Reservoirs

At present, fiber reinforce plastic (FRP) sucker rod has the advantages of high tensile strength, light weight and strong corrosion resistance which gradually applied and popularized in offshore oil and gas field. However, the bonded joint of FRP sucker rod is particularly prone to break and fall off. Current research works mainly focus on the mechanical properties of FRP sucker rod and less consideration was given to adhesive performance. This paper proposed a finite element model (FEM) of bonded joint. The maximum predicted load of bonded joint was acquired and the axial distribution of adhesion stress and slip distance in the bonding interface was studied, which can provide theoretical basic of bonded joint and extend the service life of downhole pumping operation.

Numerical investigation and structural optimization of bonded joints with fiber reinforce plastic sucker rods in offshore reservoirs

ABSTRACT Sucker rod constructed of FRP (fiber-reinforced plastic) is currently used in offshore oil and gas industries due to its high tensile strength, lightweight, and resistance to corrosion. Due to the fact that the surface of FRP sucker rod cannot be threaded, it is often attached to steel joints via adhesive technology, and the bonded joint of FRP sucker rod is particularly prone to breaking and coming off. The current research is primarily concerned with the mechanical properties of FRP sucker rods, with little emphasis on the adhesive performance of bonded connections. This research developed a numerical model with a novel bonded joint structure based on the cohesion failure criteria. An indoor test was used to determine and confirm the expected bonded joint failure load. Additionally, an orthogonal test was conducted to maximize the adhesion performance. The findings indicated that a) theaccuracy of numerical model was within 2% and b) when the groove angle was 30°, the length ratio was 2/23, each groove was 14 mm in length based on a triangular groove, and the anticipated failure stress of the bonded joint was around 443 kN, an increase of 10%.

Plastic Zr-Al-Ni-Cu-Ag bulk glassy alloys containing quasicrystalline or β-Zr plus ω-Zr phases

Zr70–76Al7–7.5Ni13–15Cu2Ag2–5 glassy alloys were prepared by melt-spinning with Zr contents up to 76 at.%, greatly exceeding the highest Zr content of 70 at.% previously reported for Zr-based glassy alloys exhibiting a calorimetric glass transition. The 70–72Zr and 74Zr alloys were also cast as bulk rods up to 1.5 mm in diameter with glass and [glass + β-Zr + ω-Zr] phases, respectively, by ejection copper-mold casting. The crystallization temperature and Vickers hardness Hv for the glassy ribbons decrease with increasing Zr content from 70 to 76 at.%. The glassy rods show high yield strength (σy) of 1225–1346 MPa, high fracture strength (σf) of 1497–1499 MPa, and large compressive plastic strain (εp) of 9.7–3.2% for the 70–72Zr alloys. Similarly, the 74Zr rod with [glass + β-Zr + ω-Zr] phases shows σy of 1325 MPa, σf of 1472 MPa, εp of 2.4%. The 76Zr thick ribbon with [glass + β-Zr + ω-Zr] phases shows, in tension, high σy of 890 MPa, σf of 988 MPa, and plastic elongation of 0.3%. The Zr-rich glassy ribbons crystallize, showing three exothermic peaks upon heating. The first-stage peak is due to the precipitation of icosahedral quasicrystal (IQ) for the 70–72Zr ribbons, and β-Zr + ω-Zr for the 74–76Zr ribbons. These annealing-induced mixed-phase ribbons with Zr content above 72 at.% exhibit good bending plasticity, even though their HV is about 41% higher than for the as-spun glassy ribbons. Similarly, the 70Zr bulk rod, with [glass + IQ] phases obtained by annealing, shows a distinct increase in σy and σf to 1485 and 1575 MPa, respectively, as well as εp of 0.6%. Thus, the plastic Zr-rich bulk rods with glass, [glass + IQ], and [glass + β-Zr + ω-Zr] phase mixtures are encouraging for the future development of a new type of high-strength structural material.

Experimental study on radial gravity currents flowing in a vegetated channel

We present an experimental study of gravity currents in a cylindrical geometry, in the presence of vegetation. Forty tests were performed with a brine advancing in a fresh water ambient fluid, in lock release, and with a constant and time-varying flow rate. The tank is a circular sector of angle $30^\circ$ with radius equal to 180 cm. Two different densities of the vegetation were simulated by vertical plastic rods with diameter $D=1.6\ \textrm{cm}$ . We marked the height of the current as a function of radius and time and the position of the front as a function of time. The results indicate a self-similar structure, with lateral profiles that after an initial adjustment collapse to a single curve in scaled variables. The propagation of the front is well described by a power law function of time. The existence of self-similarity on an experimental basis corroborates a simple theoretical model with the following assumptions: (i) the dominant balance is between buoyancy and drag, parameterized by a power law of the current velocity $\sim |u|^{\lambda-1}u$ ; (ii) the current advances in shallow-water conditions; and (iii) ambient-fluid dynamics is negligible. In order to evaluate the value of ${\lambda}$ (the only tuning parameter of the theoretical model), we performed two additional series of measurements. We found that $\lambda$ increased from 1 to 2 while the Reynolds number increased from 100 to approximately $6\times10^3$ , and the drag coefficient and the transition from $\lambda=1$ to $\lambda=2$ are quantitatively affected by D, but the structure of the model is not.

Isopod parasite influences prawn responsiveness and activity

Most bopyrid isopod parasites, which are crustaceans themselves, settle in the branchial chamber of decapod crustaceans and feed on host haemolymph. Here we report the results of an experiment on the common prawn Palaemon serratus and the parasite Bopyrus squillarum. Infected and uninfected prawns were stimulated with pokes of a plastic rod until an escape response was triggered; the number of pokes was recorded as an indicator of prawn responsiveness, whereas the time spent moving following stimulation was used as an indicator of prawn activity. Our results show that bopyrid infection affects both prawn responsiveness and activity, with infected prawns requiring more pokes to move, and moving for less time compared to uninfected prawns. In nature, such behavioural changes may impact defence mechanisms and survival of infected prawns. This could contribute to decreases in P. serratus abundance, thereby affecting the coastal ecosystems home to this species and the fisheries reliant on it, such as the Irish shrimp fishery.