Pair Of Tweezers Research Articles

Preparing dispersion-hardened materials for transmission electron microscopy

The preparation of thin foils for electron microscopy often causes difficulties for dispersion-hardened materials in which the dispersoid (normally an oxide) is not attacked by the eleetropolishing. The metal/ceramic-dispersoid-particle interface tends to produce premature perforation which is then followed by accelerated attack. In the following we shall describe a method that has proved successful in producing very good thin foils from all the dispersion-hardened materials to which it has been applied, namely aluminum with aluminum oxide, zirconium and zircaloy-2 with yttrium oxide, and high-purity iron and austenitic stainless steel with aluminum oxide. First, discs 3 mm in diameter and 0.5 mm thick are made by spark machining (or, if a slight mechanical distortion during preparation is acceptable, discs may be wet-ground to 0.2 mm thickness on emery paper while held in a special jig). The discs are then eleetropolished in an ethanol/perchloric-acid electrolyte containing 20 v/o perchloric acid. The electrolyte, contained in a double-walled beaker, is cooled with ethanol circulated in the cooling jacket from a Fiskars refrigerator; the electrolyte temperature is kept at --20°C±1°C. The arrangement is shown in Fig. 1. A simple rotary pump produces a jet of electrolyte at the specimen. The pump housing is made of P T F E ; it has an inlet in the top center. In the pump housing a magnetic rod covered with P T F E is rotated by the magnetic stirrer on which the whole arrangement stands. The electrolyte runs through two glass tubes ending on each side of the specimen, thus producing the double jet. The specimen is held in a pair of tweezers laquered with Lacomit (except at the contact points), and the tweezers are held in a retort stand. A platinum plate is used as the cathode. The shape and location of the cathode are not found to be critical ; in Fig. 1 it is placed along the back wall of the beaker almost hidden by the reflections from the surface. The specimen can be observed through a stereo microscope so that the current can be switched off immediately after perforation. Before polishing, the rim of the disc is covered with Lacomit while held in the

Studies on the Parasitic Forms of Sporotrichum schenckii in scales and crusts (I)

This paper is concerned with the parasitic forms of Sporotrichum schenckii in scales and crusts. The patient is a 1 year-old male infant, who admitted to the Narashino National Hospital for the treatment of head-trauma.About 6 months ago, a papule appeared on the right cheek, and after that new papule grew by one. They spreaded slowly and now there are two scaly rashes (7×6mm and 4×4mm) with crusts on the center of the cheek. As scales were removed by a pair of tweezers, the lesions showed erosion.The patient was not rteated for this disease to date, and family history and laboratory findings were not paticular.Several scales and crusts were examined with 20% potasium hydroxide microscopically, and many fungous elements were found. They were classified into two groups; yeast like shape and filamentous.The cells which showed the former group varied greatly in size and shape; spherical, ovoidal, ellipsoidal, clavate, broad bean shaped, racket shaped and so on, occuring singly, in pairs, small groups or short chains. They measured 2-40μ in length. Occasionally, septa, nucleus, ring or sediment was observed in them. Furthermore, there were a few cells which resembled Hulle cells of Aspergillus nidulans or Aspergillus ustus.In the latter one there were long slender hyphae (about 1μ in width), short thick hyphae, and ones with the enlargement of intercalary or terminal cells. The cells had thick walls and were characterized by considerable variation in size and shape nevertheless the walls of hyphae was thin. On the other hand, a few beads shaped filaments were observed.For cultures two kinds of slants were employed. One was Sabouraud's glucose agar slant and the other Sabouraud's glucose agar supplemented with actidione (0.5mg per ml) and chloramphenicol (0.05mg per ml). Three slants were used for each medium. Scales and crusts were inoculated on each slant and incubated at room temperature. After 4 days many small and white colonies grew on all slants. After 7 days the surface of them became moist, wrinkled and membraneous. The color was black. Microscopically, the delicate, branching, septate hyphae were observed, and they beared spherical or pyriform microconidia laterally, or in groups from the ends of lateral branches. The microconidia were about 2-5μ in diameter.The yeast like phase of it could be obtained on brain-heart infusion agar supplemented with 1% glucose after incubation for 7 days at 37°C.The isolated fungus was determined Sporotrichum schenckii. The growth of other fungus was never recognizable within 45 days except a few colonies of Staphylococcus epidermidis.

Locking tweezers made from a hypodermic needle

A stainless steel wire is fitted inside a veterinary needle. The end of the wire and the bent point of the needle form the gripping surfaces of a pair of tweezers. A camera cable release with a locking collar controls the position of the wire and enables the tweezers to be locked on to an object.

Tools for the Workshop

A Monthly Selection of Recent Equipment and New Methods. We have recently received details of some of the Pryor marking equipment, which includes founts of interchangeable steel type, each packed in a fitted oak case complete with a hand holder of patented design (FIG. 1). The type packs including such hand holders are in sizes 1/16 in., 3/32 in. and ⅛ in.; they contain 100 pieces of type in a selected variety of figures and letters and 12 spacing pieces, together with a pair of tweezers. An Allen key for operating the patent type‐locking device which is a feature of the holders is provided with each set. Both the holders and type have a satin nickel finish.