Mechanisms Of Fracturing In Structures Built From Topologically Interlocked Blocks

Failure of materials is in many cases associated with initiation and subsequent propagation of macroscopic fractures. Consequently, in order to increase the strength, one needs to inhibit either crack initiation or propagation. The principle of topological interlocking provides a unique opportunity to construct materials and structures in which both routes of the strength increase can be realised. Materials and structures built on the basis of this principle consist of many elements which are hold together by the special geometry of their shape, together with an external constrain. The absence of the binder phase between the elements allows the interfaces to arrest macroscopic crack propagation. In addition, with sufficiently small size of the elements an increase in local strength and, possibly, in the stress for crack initiation can be achieved by capitalising on the size effect. Furthermore, the ability of some interlocking structures to tolerate missing elements can serve to prevent the avalanche-type failure initiated by failure of one of the elements. In this paper, experimental results and a theoretical analysis with regard to this possibility are presented

MICE: the Muon Ionization Cooling Experiment. Step I: First Measurement of Emittance with Particle Physics Detectors

The Muon Ionization Cooling Experiment (MICE) is a strategic R&D project intended to demonstrate the only practical solution to providing high brilliance beams necessary for a neutrino factory or muon collider. MICE is under development at the Rutherford Appleton Laboratory (RAL) in the United Kingdom. It comprises a dedicated beamline to generate a range of input muon emittances and momenta, with time-of-flight and Cherenkov detectors to ensure a pure muon beam. The emittance of the incoming beam will be measured in the upstream magnetic spectrometer with a scintillating fiber tracker. A cooling cell will then follow, alternating energy loss in Liquid Hydrogen (LH2) absorbers to RF cavity acceleration. A second spectrometer, identical to the first, and a second muon identification system will measure the outgoing emittance. In the 2010 run at RAL the muon beamline and most detectors were fully commissioned and a first measurement of the emittance of the muon beam with particle physics (time-of-flight) detectors was performed. The analysis of these data was recently completed and is discussed in this paper. Future steps for MICE, where beam emittance and emittance reduction (cooling) are to be measured with greater accuracy, are also presented

Models of hysteretic behavior of shape-memory materials

Shape memory alloys (SMA) are metallic alloys that can retain their initial form by memorising it between two transformation phases. Whilst loading such materials, the hysteresis loops are observed. There was proposed the model to describe the hysteresis loops of SMA wires, based on experimental stress strain diagram. The proposed model uses the least squares method. The applied approach shows good agreement with the empirical dat

Pharmacological characterization of novel synthetic opioids (NSO) found in the recreational drug marketplace

Novel synthetic opioids (NSO) are increasingly encountered in illicit heroin and counterfeit pain pills. Many NSO are resurrected from older biomedical literature or patent applications, so limited information is available about their biological effects. Here we examined the pharmacology of three structurally-distinct NSO found in the recreational drug market: N-(1-(2-phenylethyl)-4-piperidinyl)-N-phenylbutyramide (butyrylfentanyl), 3,4-dichloro-N-[(1R,2R)-2-(dimethylamino)cyclohexyl]-N-methylbenzamide (U-47700) and 1-cyclohexyl-4-(1,2-diphenylethyl)piperazine (MT-45). Radioligand binding and GTPγS functional assays were carried out in cells transfected with murine mu- (MOR-1), delta- (DOR-1) or kappa-opioid receptors (KOR-1). Antinociceptive effects were determined using the radiant heat tail flick technique in mice, and opioid specificity was assessed with the mu-opioid antagonist naloxone. Butyrylfentanyl, U-47700 and MT-45 displayed nM affinities at MOR-1, but were less potent than morphine, and had much weaker effects at DOR-1 and KOR-1. All NSO exhibited agonist actions at MOR-1 in the GTPγS assay. Butyrylfentanyl and U-47700 were 31- and 12-fold more potent than morphine in the tail flick assay, whereas MT-45 was equipotent with morphine. Analgesic effects were reversed by naloxone and absent in genetically-engineered mice lacking MOR-1. Our findings confirm that butyrylfentanyl, U-47700 and MT-45 are selective MOR-1 agonists with in vitro affinities less than morphine. However, analgesic potencies vary more than 30-fold across the compounds, and in vitro binding affinity does not predict in vivo potency. Taken together, our findings highlight the risks to humans who may unknowingly be exposed to these and other NSO when taking adulterated heroin or counterfeit pain medications. This article is part of the Special Issue entitled ‘Designer Drugs and Legal Highs.’ © 201