An optical transceiver has a communications mode and an optical time domain reflectometer (OTDR) mode. The transceiver comprises a transmitter channel and a receiver channel operable, in the communications mode, to respectively transmit and receive communications signals through respective external optical fibers. The transceiver also comprises a guide arrangement for guiding, in the OTDR mode, a reflected OTDR signal along a path from the transmitter channel into the receiver channel. A method of obtaining test data for an optical fiber in an optical data communications subsystem is also disclosed.

Embodiments of the present disclosure provide methods for allocating bandwidth to a plurality of traffic containers of a passive optical network. The method comprises receiving upstream data from a plurality of traffic containers of the passive optical network and passing the upstream data to a traffic manager. The method further comprises dynamically changing the allocated bandwidth based at least in part on the amount of the upstream data stored in one or more queues of the traffic manager.

An undersea long-haul transmission system includes an optical fiber transmission span and a coherent detection and digital signal processing module for providing dispersion compensation. The transmission span includes at least one fiber pair comprising substantially equal lengths of a positive-dispersion first fiber and a negative-dispersion second fiber that are configured to provide a signal output at transmission distances greater than 10,000 km, in which the combined accumulated dispersion across the operating bandwidth does not exceed the dispersion-compensating capacity of the coherent detection and digital signal processing module. Further described is a fiber for use in an undersea long-haul transmission span. At a transmission wavelength of 1550 nm, the fiber has a dispersion coefficient in the range of −16 to −25 ps/nm·km, and a dispersion slope in the range of 0.04 to 0.02 ps/nm2·km.

One aspect provides an optical communication system. The system includes an optical-to-digital converter, a frequency estimator and a symbol synchronizer. The optical-to-digital converter is configured to receive an optical OFDM bit stream including an OFDM symbol bearing payload data and a symbol header preceding the OFDM payload data. The frequency estimator is configured to determine a carrier frequency offset of the payload data from the symbol header. The symbol synchronizer is configured to determine a starting location of the payload data within the bit stream by cross-correlating a synchronization pattern within the symbol header with a model synchronization pattern stored by the symbol synchronizer.

Methods and apparatus related to the detection of low-rate visible light communication (VLC) signals and the recovery of information communicated by the VLC signals are described. Various methods and apparatus are well suited for embodiments in which a device, e.g., a smartphone, including a camera which uses a rolling shutter. The rolling shutter facilitates the collection of different time snapshots of a received low rate time varying VLC signal with different pixel rows in the image sensor of a frame corresponding to different time snapshots. In some embodiments, demodulation is used to recover and identify a single tone being communicated in a frame from among a plurality of possible alternative tones that may be communicated, each different tone corresponding to a different set of information bits.

Techniques are provided describing a first connector unit that receives first data from a first transceiver and a second connector unit that receives second data from a second transceiver. A switch unit is configured to receive first switch data from the first connector unit at a first data rate and second switch data from the second connector unit at the first data rate. A third connector unit receives the first switch or the second switch data from the switch unit and a second portion of the second data from the second connector unit. The third connector unit also sends the first switch data to a host port when the first connector unit receives the first data and to send the second switch data and the second portion of the second data to the host port when the second connector unit receives the second data.

Additional bandwidth is provisioned to layer 2/3 networks by initially provisioning optical wavelength channels to meet incremental needs for additional capacity. When bandwidth requirements grow large enough, a wavelength-sized channel is provisioned to meet the bandwidth needs, and the previously provisioned optical wavelength channels are freed up to be reused for additional growth. The optical wavelength channels may be channelized VLANs mapped to resizable optical channel data units such as ODUflex units.

This invention relates to provisioning wavelength-selective switches and reconfigurable optical add-drop multiplexers to minimize the bandwidth narrowing effect from the optical filters. Novel architectures and methods are disclosed that can significantly reduce bandwidth-narrowing on channels in a reconfigurable WDM network where a large number of optical filter elements are cascaded. Instead of blocking unused channels as in the prior art, unused channels are selectively provisioned depending on the state of their adjacent channels. Unused adjacent channels of an active channel are provisioned to follow the same path as the active channels. As each channels is deployed, the channel frequency is selected so as to minimize bandwidth narrowing.

Optical fiber-based distributed communications systems that provide and support both RF communication services and digital data services are disclosed herein. The RF communication services and digital data services can be distributed over optical fiber to client devices, such as remote antenna units for example. In certain embodiments, digital data services can be distributed over optical fiber separate from optical fiber distributing RF communication services. In other embodiments, digital data services can be distributed over common optical fiber with RF communication services. For example, digital data services can be distributed over common optical fiber with RF communication services at different wavelengths through wavelength-division multiplexing (WDM) and/or at different frequencies through frequency-division multiplexing (FDM). Power distributed in the optical fiber-based distributed communications system to provide power to remote antenna units can also be accessed to provide power to digital data service components.

An optical transceiver of one embodiment includes a transmitter optical subassembly to transmit an optical signal, a receiver optical subassembly to receive an optical signal, a mother board, a daughter board, and a housing. The mother board mounts electronic circuits that electrically communicate with the optical transmitter optical subassembly and the receiver optical subassembly. The daughter board mounts other electronic circuits that electrically communicate with the optical transmitter optical subassembly and the receiver optical subassembly. The daughter board has an extra area mounting a portion of the other electronic circuits. The housing defines a space for installing the optical transmitter optical subassembly, the receiver optical subassembly, the mother board, and the daughter board. The extra area is disposed outside the space.

The invention relates to embedding data symbols of a data signal into a luminance output of an illumination device. The device includes a controller configured for receiving a first base pattern and a second base pattern within a frame period, and generating a shifted second pattern by phase shifting the second base pattern within the frame period with respect to the first base pattern in response to the data signal such that the data symbols are embedded in the luminance output of the device. The device also includes a first light source configured to generate a first luminance output in response to the first base pattern and a second light source configured to generate a second luminance output in response to the shifted second pattern. The first and second luminance outputs have different output spectra and the luminance output of the illumination device comprises both the first and second luminance outputs. With this approach, the short-time average light output of the illumination device remains constant, decreasing the visible flicker and allowing the use of lower switching frequencies relative to the prior art approaches.

A skiving tool for manufacturing a rotationally symmetrical periodical structure on a work piece by means of a power skiving method. The skiving tool comprises a base body comprising a central rotation axis and a plurality of receiving openings and a plurality of cutter bars, fewer than or equal to the number of receiving openings. Each of the receiving openings has an elongate shape having a longitudinal axis, and the receiving openings can be arranged uniformly around the central rotation axis. The longitudinal axes of the receiving openings are generators of a rotation hyperboloid, which is arranged rotationally symmetrical to the central rotation axis.

A cutting insert having a plurality of corner cutting edges has an upper face, a lower face, two longitudinal side faces and two transversal side faces connecting the upper face and the lower face. A through hole passes through central parts of the upper face and the lower face. The longitudinal side faces are opposite to each other and normal to both upper and lower faces, as are the transversal side faces. The upper face and the lower face are each provided with two chip discharge grooves, each chip discharge groove extending along a corresponding one of the transversal side faces, the two chip discharge grooves being inclined oppositely in the transverse direction so that the upper face and the lower face are each provided with two corner cutting edges at diagonally opposite corners. The longitudinal length of the insert is longer than the transversal length of the insert. The cutting insert can be mounted stably to a small-diametered cutter with a sufficient mounting surface.

A toolholder assembly includes a toolholder body having a coolant passage and a cutting insert seated within a recess of the body. The cutting insert includes an insert orifice extending between a top face and a bottom face that aligns with the coolant passage. A lock pin includes a lock pin orifice that aligns with and is in fluid communication with the coolant passage of the body. The lock pin orifice has an outlet port to allow the fluid to flow through the lock pin orifice and exit through the outlet port. A lock pin ring includes a coolant port in fluid communication with the outlet port of the lock pin to effectively discharge cooling fluid in the direction of a cutting area of the cutting insert.

A tool for both severing the end of a pipe and beveling the cut end includes a spiral cutting mill having an elongate end received in the bore of a frustoconical shell cutter. The shell cutter is locked for rotation with the cutting mill such that a single tool has two cutting surfaces, one for severing a length of pipe and one for beveling the outer edge thereof.

It is an object of the present invention to provide a sintered cBN compact having excellent wear resistance and fracture resistance even in machining centrifugally cast iron having a property of being difficult to machine, and to provide a sintered cBN compact tool. A sintered cBN compact of the present invention contains 20% by volume or more and 65% by volume or less of cBN and, as a binder, 34% by volume or more and less than 80% by volume of Al2O3, at least one selected from the group consisting of nitrides, carbides, carbonitrides, borides, and boronitrides of Zr and solid solutions thereof (hereinafter, referred to as “X”), and ZrO2, the total amount of X and ZrO2 being 1.0% by volume or more and 6.0% by volume or less, the volume ratio of ZrO2 to Al2O3, ZrO2/Al2O3, being 0.010 or more and less than 0.100, in which the ratio Itetragonal ZrO2(101)/IαAl2O3(110) is 0.1 or more and 3 or less, where Itetragonal ZrO2(101) is the intensity of the (101) plane of tetragonal ZrO2 and IαAl2O3(110) is the intensity of the (110) plane of αAl2O3 among X-ray diffraction peaks of the sintered cBN compact.

Electrode milling cutter for machining spot welding electrodes, said electrode milling cutter having one or more milling edges, wherein at least one of the milling edges is interrupted by one or more cut-outs at one or more points. The invention also relates to a milling device and to an apparatus for subsequently machining spot welding electrodes.

In a cutting tool for chip removing machining a holder for a cutter has a body received therein and movable with surfaces to bear against the cutter for defining the position of the cutter in the direction of an intended axis of rotation of the holder as well as a screw which may be screwed in a threaded bore in the holder. Spring members are arranged to act between the holder and the body for biasing the body against said screw portions.

A double-sided cutting insert may generally comprise a top surface, a bottom surface, at least one side surface interconnecting the top surface and the bottom surface and forming at least one cutting edge, a through hole extending between the top surface and bottom surface, wherein each of the top surface and bottom surface comprise at least one anti-rotation element. The cutting insert may comprise a single anti-rotation element on the top surface and a single anti-rotation element on the bottom surface. The anti-rotation element may be proximate to the through hole. A cutting tool using the cutting inserts, as well as methods of making and using the same are also described.

Provided is a surface-coated cemented carbide insert obtained by containing at least WC powder and Co powder as raw materials, including a WC-based cemented carbide obtained by forming and sintering mixed raw materials containing at least any of (a) Zr compound powder, Nb compound powder, and Ta compound powder, (b) complex compound powder of Nb and Ta, and Zr compound powder, (c) complex compound powder of Nb, Ta, and Zr, (d) complex compound powder of Nb, Zr, and Ta compound powder, and (e) complex compound powder of Ta and Zr, and Nb compound powder, as essential powder components, as a substrate, and forming a hard coating layer on the substrate by vapor deposition, in which a Co enrichment surface region is formed in a substrate surface, Co content in the Co enrichment surface region satisfies to be between 1.30 and 2.10 (mass ratio) of Co content in cemented carbide.

A cutting insert (14) is formed with an insert aperture (32) opening out to insert top and bottom surfaces (14A, 14B) of the cutting insert (14). In a plan view of the insert top surface (14A), the cutting insert (14) and the insert aperture (32) both have oblong shapes which are elongated along a common insert longitudinal axis (AIL). The aperture (32) includes first and second side surfaces (32A1, 32A2) which each extend along the insert longitudinal axis (AIL), and aperture first and second end surfaces (32B1, 32B2) which each extend transverse relative to the insert longitudinal axis (AIL). At least one of the aperture first and second end surfaces (32B1, 32B2) is formed with a clamping lip (32C1, 32C2).

A cutting tool used for grooving and turning operations where a cutting insert is resiliently securable in a holder blade. The cutting insert includes an insert central lower surface located between, and recessed with respect to, two insert lower component surfaces, each having an insert lower abutment surface. At least one of the two insert lower component surfaces includes an insert inner curved ramp extending from its insert lower abutment surface to the adjacent insert lower intermediate surface and at least the other of the two insert lower component surfaces includes an insert outer curved ramp extending from its insert lower abutment surface to an adjacent end surface.

A cutting insert includes a first surface having a first rake surface, a second surface having a second rake surface, a central axis of the insert extending between the first and second surfaces, four side surfaces extending between the first surface and the second surface, and four cutting edges. Each cutting edge has a first cutting edge component and a second cutting edge component and being associated with a respective one of the first and second surfaces and with two respective ones of the side surfaces. The first rake surface is identical to the second rake surface and the first rake surface and the second rake surface are oriented at a 90° angle to each other about the central axis of the insert.

The present invention provides a hybrid digital and channel microfluidic device in the form of an integrated structure in which a droplet may be transported by a digital microfluidic array and transferred to a microfluidic channel. In one aspect of the invention, a hybrid device comprises a first substrate having a digital microfluidic array capable of transporting a droplet to a transfer location, and a second substrate having a microfluidic channel. The first and second substrates are affixed to form a hybrid device in which an opening in the microfluidic channel is positioned adjacent to the transfer location, so that a droplet transported to the transfer location contacts the channel opening and may enter the channel. The invention also provides methods of performing separations using a hybrid digital and channel microfluidic device and methods of assembling a hybrid digital microfluidic device.

A low-carbon, material consumption-free air cleaner includes a rectangular box body, a fan, a negative ion generator unit and a dielectric barrier discharge actuator respectively arranged at upper part, middle part and lower part of the rectangular box body, an air input port disposed at the bottom side of the dielectric barrier discharge actuator, and air output port disposed at the top side of the rectangular box body.

The present disclosure relates to an apparatus and process for forming medical devices from an injectable composition. The apparatus includes a supply assembly configured to maintain and selective dispense a first precursor and a second precursor, a mixing assembly configured to mix the first and second precursors, and at least one catalyzing element including a transition metal ion to aid in the polymerization of the first and second precursors. The process includes dispensing a volume of the first precursor and a volume of the second precursor into a mixing assembly and mixing the first and second precursors. The first and second precursors each possess a core and at least one functional group known to have click reactivity with each other. The mixed precursors are contacted with a transition metal catalyst to produce a flowable composition for use as a medical device.

A slurry bubble column reactor with a gas distribution arrangement comprising an upper sparger, a lower sparger, and an open-ended tube. Gas from the lower sparger enters the tube and lowers the density of slurry in the tube. The difference in slurry density causes the slurry in the tube to rise, causing slurry outside the tube to move down, maintaining circulation and flushing catalyst from the vessel wall.

A laminated body composed of a holding member and an inner cylinder is arranged between a heat generation element, which is electrically energized to generate heat, and a case which covers the heat generation element, and the inner cylinder has an upstream side end portion extended to a more upstream side than an upstream side end face of said heat generation element and an upstream side end face of said holding member to form an extension portion, which is formed with a protruding portion protruding to an inner side in a diametrical direction. A flow of an exhaust gas, which flows backwards after colliding with the heat generation element, will be obstructed by said protruding portion. As a result, the backflow exhaust gas stops flowing into a gap between the case and the inner cylinder.

A biosensor is provided. The biosensor is used to sense a biological sample and has a code representing features of the biosensor. The biosensor includes a substrate and a conductive layer. The conductive layer is disposed on a first side of the substrate and includes a first conductive loop and a second conductive loop. The first conductive loop is formed between a first node and a second node and has a first impedance. The second conductive loop is formed between the second node and a third node and has a second impedance. The code is determined according to a comparison result between the second impedance and the first impedance.

A centrifuge to which sample tubes can be introduced while the centrifuge is in motion. The centrifuge comprises a carousel having an upper portion and a lower portion. The upper portion of the carousel has a plurality of positions for sample tubes for a centrifugation operation, a plurality of drive mechanisms attached to the upper portion of the carousel, a movable element mounted upon each drive mechanism, the movable element capable of traversing the length of the drive mechanism when the drive mechanism is actuated, a sample tube-holding assembly comprising a sample tube holder and a bearing attached to each movable element, and at least one balancing element capable of contributing to a force vector that cancels an imbalance vector generated by rotation of the centrifuge.

A micro device includes a substrate and a structure configured to bind to an object or a material, or not to bind to an object or material. The structure has a roughness based on a roughness of the object or material. For example, a microarray includes a substrate and a well positioned in the substrate and configured to bind to a type of bead. The well has a roughness based on a roughness of the type of bead to which the well is configured to bind. The roughness of the well is controlled by controlling a position and number of striations in the side of the well. In another example, a moveable component of a micro device may have a roughness different from a roughness of an adjacent component, to reduce the likelihood of the moveable component sticking to the adjacent component.

The present invention includes microfluidic systems having a microfabricated cavity that may be covered with a removable cover, where the removable cover allows at least part of the opening of the microfabricated cavity to be exposed or directly accessed by an operator. The microfluidic systems comprise chambers, flow and control channels formed in elastomeric layers that may comprise PDMS. The removable cover comprises a thermoplastic base film bonded to an elastomer layer by an adhesive layer. When the removable cover is peeled off, the chamber is at least partially open to allow sample extraction from the chamber. The chamber may have macromolecular crystals formed inside or resulting contents from a PCR reaction. The invention also includes a method for making vias in elastomeric layers by using the removable cover. The invention further includes methods and devices for peeling the peelable cover or a removable component such as Integrated Heater Spreader.

Bioprinting station (1) comprising:—a Bioprinting device (4) adapted to deposit a pattern of biological material (2) onto an area of interest (3a) of a substrate (3),—an imaging system (15) adapted to acquire an image of the substrate (3) and to reveal on the acquired image the area of interest (3a) with respect to a remaining part (3b) of the substrate (3), the acquired image of the substrate (3) being processed so as to detect the revealed area of interest (3a) on the acquired image and to determine the pattern corresponding to the area of interest (3a) detected on the acquired image.

An apparatus for sampling and storing biological fluids from a human or animal subject is provided. In one embodiment of the present disclosure, the apparatus includes a main body, lancet carrier or hub, lancet, lancet trigger, capillary tube, and sample compartments for collecting and storing dried blood and other bodily fluids. The lancet hub supports a lancet and provides for moving the lancet longitudinally between a first retracted position and a second extended position. The device includes a capillary tube having an internal diameter sized to draw and retain fluid from a contacted source using capillary action. The main body of the apparatus further includes a sample compartment for holding sampling and storage materials. In at least one embodiment of the present disclosure, the sample compartment can be accessed by lifting sample compartment lid. Also included is a new “fan” or “daisy” shaped collection material format for use in collecting and preserving samples.

The present invention provides molecular biosensors capable of signal amplification, and methods of using the molecular biosensors to detect the presence of a target molecule.

The present invention is for extremely pure solutions of chlorine dioxide, methods for making such solutions and to compositions and methods for storing, shipping and using such solutions. Generally, the chlorine dioxide solutions of the invention are aqueous solutions containing about 2500 ppm or less of total impurities. The chlorine dioxide solution can be prepare by passing dilute highly pure chlorine gas through a bed of substantially solid sodium chlorite and contacting the resulting chlorine dioxide gas with a liquid.

The invention refers to a device for recording biometric data, such as lines of finger or hand. A rest is provided on the device for the hand and finger, respectively, as well as an illuminating unit. According to the invention an illuminating unit and/or rest is provided that can traverse and be positioned.

This disclosure describes an optical method of detecting the presence of pressure-sensitive labels, using the reflective properties of their edges. Labels that are removably attached to a liner are moved through a light beam that is directed across their direction of motion so the light impinges on the labels at a predetermined angle of incidence. The light remains in its plane of incidence when it reflects off all parts of the liner and labels except the labels' edges. Due to the angularity of the labels' edges, the light beam is deflected out of the plane of incidence upon reflection off the edges, thus enabling detection of the label edges by light reflected out of the plane of incidence.

A 3D image sensor includes a depth pixel that includes; a photo detector generating photo-charge, first and second floating diffusion regions, a first transfer transistor transferring photo-charge to the first floating diffusion region during a first transfer period in response to a first transfer gate signal, a second transfer transistor transferring photo-charge to the second floating diffusion region during a second transfer period in response to a second transfer gate signal, and an overflow transistor that discharges surplus photo-charge in response to a drive gate signal. Control logic unit controlling operation of the depth pixel includes a first logic element providing the first transfer gate signal, a second logic element providing the second transfer gate signal, and another logic element providing the drive gate signal to the overflow transistor when the first transfer period overlaps, at least in part, the second transfer period.

An approach for IR-based metrology for detecting stress and/or defects around TSVs of semiconductor devices is provided. Specifically, in a typical embodiment, a beam of IR light will be emitted from an IR light source through the material around the TSV. Once the beam of IR light has passed through the material around the TSV, the beam will be analyzed using one or more algorithms to determine information about TSV stress and/or defects such as imbedded cracking, etc. In one embodiment, the beam of IR light may be split into a first portion and a second portion. The first portion will be passed through the material around the TSV while the second portion is routed around the TSV. After the first portion has passed through the material around the TSV, the two portions may then be recombined, and the resulting beam may be analyzed as indicated above.

A system and method for mounting a section onto a substrate, the system comprising: a fluid channel including: a fluid channel inlet that receives the section, processed from a bulk embedded sample by a sample sectioning module positioned proximal the fluid channel inlet, a section-mounting region downstream of the fluid channel inlet, and a fluid channel outlet downstream of the section-mounting region; a reservoir in fluid communication with the fluid channel outlet; and a manifold, fluidly coupled to the reservoir, that delivers fluid from the reservoir to the fluid channel inlet, thereby transmitting fluid flow that drives delivery of the section from the fluid channel inlet toward the section-mounting region.

The present disclosure relates to an improved device and methods for adapting to a laser diffraction apparatus used for measuring particle size distribution and density of the plume of a powder composition emitted from a dry powder inhaler.

A method of optically determining the presence of volcanic ash within a cloud comprises emitting a circularly polarized illuminating beam within a cloud and analyzing backscatter light to identify the presence of volcanic ash within the cloud. The method further includes determining the degree to which the cloud has altered the polarization state of the emitted beam. The index of refraction of the backscatter light and the opacity of the backscatter light are also analyzed.

A system for imposing and analyzing surface acoustic waves in a substrate to determine characteristics of the substrate is disclosed. Optical elements and arrangements for imposing and analyzing surface acoustic waves in a substrate are also disclosed. NSOM's, gratings, and nanolight elements may be used to impose surface acoustic waves in a substrate and may also be used to measure transient changes in the substrate due to the passage of surface acoustic waves therethrough.

A dispersion managed interferometric fiber optic gyroscope comprising: a coupler coupled to the broadband light source via a first input fiber; an IOC comprising: a beamsplitter that directs the input signal to a first output and a second output; a combiner configured to combine a first return signal from the first output and a second return signal from the second output into a combined return signal; an integrated optical circuit input coupled to the coupler via a second input fiber; a fiber optic gyroscope sensing coil coupled to a first pigtail fiber and second pigtail fiber, the sensing coil comprising sensing fibers, wherein at least one dispersion slope of at least one of the first input fiber, second input fiber, first pigtail fiber, second pigtail fiber, and the sensing fibers is selected such that the signals at the IOC input has a second order coherence substantially equal to two.

Techniques and devices for measuring polarization crosstalk in birefringence optical media including polarization maintaining fiber.

A system, that includes a hybrid sensor that comprises: a monochromatic portion that is arranged to obtain a monochromatic image of a first area of an object; a multiple-color portion that is arranged to obtain a multi-colored image of a second area of the object; wherein the monochromatic portion comprises monochromatic sensing elements that sense radiation of a same frequency band; wherein the multiple-color portion comprises color sensing elements of different types, wherein different types of color sensing elements are associated with different frequency bands.

Within machine vision, object movement is often estimated by applying image evaluation techniques to visible light images, utilizing techniques such as perspective and parallax. However, the precision of such techniques may be limited due to visual distortions in the images, such as glare and shadows. Instead, lidar data may be available (e.g., for object avoidance in automated navigation), and may serve as a high-precision data source for such determinations. Respective lidar points of a lidar point cloud may be mapped to voxels of a three-dimensional voxel space, and voxel clusters may be identified as objects. The movement of the lidar points may be classified over time, and the respective objects may be classified as moving or stationary based on the classification of the lidar points associated with the object. This classification may yield precise results, because voxels in three-dimensional voxel space present clearly differentiable statuses when evaluated over time.

An adaptive optics scanning system using a beam projection module with four or more axes of motion that can project and control the position and angle of a beam of light to or from an adaptive optics element. The adaptive optics scanning system is compact in size, overcoming the challenges of a traditional lens and mirror based pupil relay design. The adaptive optics scanning system has little to no dispersion, chromatic aberration, and off-axis aberration for improved optical performance. The system and methods for calibrating and optimizing the system are described. A modular adaptive optics unit that scans and interfaces an adaptive optics element is described.

A ring binder mechanism includes an elongate plate having a longitudinal axis. Hinge plates are supported by the plate for pivoting relative to the elongate plate. Ring members are mounted on the hinge plates and moveable between a closed position and an open position. A control structure is supported by the elongate plate and controllably pivots the hinge plates to move the ring members between the closed and open positions. The control structure has a travel bar connected to the hinge plates for moving the hinge plates between the closed and open positions. A spring biases the travel bar toward the closed position.