Towards achieving nanofinish on silicon (Si) wafer by μ-wire electro-discharge machining

This study investigates the use of nanopowder-mixed dielectric oil and temporary metallic coating on highly doped Si sample to achieve nanometric surface roughness using μ-WEDM operation. To achieve this, two different nanopowders were used in dielectric medium with two different temporary metallic coating in the workpiece. This is with Al and C with metallic coating of (gold) thickness 160 nm and 320 nm. Further, the discharge energy level was varied into two proximate stages (80 V/13 pF and 85 V/0.1 nF). The results show that nanopowder-assisted μ-WEDM process has improved the material removal rate (MRR) by ~ 44.5% (maximum). However, the spark gap (SG) has also been increased to a maximum of 60% than without nanopowder assisted the μ-WEDM process. Further, it was found in our study that graphite (C) nanopowder usually generates lower spark gap as compared to aluminum (Al) nanopowder. It has also been observed that at specific μ-WEDM condition, coating thickness, and powder concentration C, Al can easily produce nanometric average surface roughness (ASR) (for C lowest ASR was 76 nm and for Al lowest ASR was 83 nm). From the findings, it can be understood that ASR can be improved maximum ~ 65% for C nanopowder and ~ 51% for Al nanopowder-assisted μ-wire electro-discharge machining as compared to conventional μ-WEDM of Si wafer. Machining stability and evenness of the machined slots were also improved by a significant margin when nanopowder-assisted μ-wire electro-discharge machining method was applied

Management of perforated corneal ulcer with iris prolapse by cyanoacrylate glue: A case report

We report a rare case of perforated corneal ulcer due to recurrent viral keratitis with stromal necrosis and iris prolapse. The patient was 75 years old farmer, normotensive, diabetic, and presented with complaints of pain, watering, photophobia, redness and dimness of vision in the left eye. The left eye's visual acuity was perception of light and projection of rays in all four quadrants. Slit lamp examination found swollen eyelids, matted eyelashes, congested conjunctiva, seidel test positive, an inferonasal corneal perforation, shallow anterior chamber, irregular pupil, and prolapse of the iris through the perforated cornea. The patient was diagnosed with a left-sided perforated corneal ulcer (recurrent viral keratitis with stromal necrotizing variety) having iris prolapse. The perforation was sealed by cyanoacrylate glue and a soft bandage contact lens. This improved the patient’s condition. Early medical and surgical interventions thus can save vision as well as the eyeball. Bangabandhu Sheikh Mujib Medical University Journal 2023;16(1): 66-69

Management of perforated corneal ulcer with iris prolapse by cyanoacrylate glue: A case report

We report a rare case of perforated corneal ulcer due to recurrent viral keratitis with stromal necrosis and iris prolapse. The patient was 75 years old farmer, normotensive, diabetic, and presented with complaints of pain, watering, photophobia, redness and dimness of vision in the left eye. The left eye's visual acuity was perception of light and projection of rays in all four quadrants. Slit lamp examination found swollen eyelids, matted eyelashes, congested conjunctiva, seidel test positive, an inferonasal corneal perforation, shallow anterior chamber, irregular pupil, and prolapse of the iris through the perforated cornea. The patient was diagnosed with a left-sided perforated corneal ulcer (recurrent viral keratitis with stromal necrotizing variety) having iris prolapse. The perforation was sealed by cyanoacrylate glue and a soft bandage contact lens. This improved the patient’s condition. Early medical and surgical interventions thus can save vision as well as the eyeball. Bangabandhu Sheikh Mujib Medical University Journal 2023;16(1): 66-69

Road traffic injury prevention in Malaysia: Research and practice

Road traffic injuries (RTIs) are a major cause of mortality, morbidity and disability in Malaysia contributing more than 23 per 100,000 people die and additional 71 per 100,000 people are injured or disabled every year. Though the upward trend of RTIs dropped slowly but the road traffic deaths have been increasing from 2,303 in 1974 to 6,872 in 2010. This article is an attempt to review the current impact of road safety initiatives carried out by the Malaysian Government and other organizations through published literature

Optimization of low normal force contact spring

Enable the design of a small contact spring for applications requiring high density, high speed and high durability. A low normal force contact spring with high performance is fabricated using a unique combined technology (photo resist lithography and electro fine forming technology). To determine an appropriate hertz stress by several radius contact R (5-200μm) with low normal force (0.10N-0.16N at 0.45mm) is designed. For a reliable contact spring, NiCo material is selected because its material characteristics are better than commercial contact spring material. By the experiment, it is proved that a low normal force spring with higher hertz stresses which is 5μm radius can provide a stable reliable contact resistance from the first contact than 200μm radius. The evaluated results by the experiment currently proved the durability of 0.30 million contact cycles (less than 50m.) without any difficulty. In this research, we focused to investigate an appropriate Hertz stress, which will be utilize in future design concept for miniature size contact spring. We think this method will be very important to decrease a total material cost in connector business field

Development of low normal force contact with stable performance

製品の極小化が進むに従い、コネクタ端子の寸法も小さくする必要がでてきた。 しかし、それでは端子の接圧が下がってしまい、コネクタのコンタクトとして不安定な接点となるため、既存の技術では打開できない接触不安定の問題を抱えていた。我々はその問題を打開するため、今まで培ってきた高ハーツストレスの原理を極小コネクタに応用することを検討した。ハーツストレスを高くするため、コンタクトの先端を鋭くする必要があり、従来のスタンピング 技術ではR50mm が限界となっていたが、我々はスクライビングと言う斬新な技術を適応することで今までにできなかった先端R5mm の突起を作ることに成功した。 これにより、ハーツストレスが従来と比べ5 倍も高くなり、僅か0.2N の低荷重でも安定した電気的接続信頼性が得られることが判明した。更に、実際のコネクタと同等の条件にて接触抵抗を測定したところ非常に安定しており、挿抜試験においてもバラツキは ± 5mΩ以内であった。この研究により、量産性のある製造技術で微小突起をコンタクト接触部に付加することで、従来では困難であった極小コネクタを実現できることが確認できた。更に、DDR コネクタなどの従来のコネクタにも本技術を適応することにより、一括挿入が可能となるため、大幅なコスト削減が可能となる

Large core diameter POF/PCF optical switch using shape memory alloy (SMA) coil actuator for local area network (LAN) system

The polymer optical fiber (POF) is mostly suitable for house held optical switches because of its large core diameter. A high performance optical switch building process is described. In order to achieve high performance switching and low data loss, we examine different technique while building different parts. Furthermore, we show the comparison of surface roughness of POF/PCF using different processing methodology to minimize the optical insertion loss. This research developed a fiber fixing Jig for Mechanical polishing method, and we discovered that, the Mechanical polishing method able to provide 1/3 (0.08 dB) optical insertion loss than the Mechanical cutting method. Another challenge was to build the main structure of the switch, and how to Seal inside’s matching oil properly. As long as, our target is to build a low-cost switch, we selected an acrylic substrate for the body. Switching speed is less than 0.5 second, and the insertion loss of the fabricated switch is 0.4 to 0.5 dB. The insertion loss is 0.06 to 0.09 dB when using index-matching oil

Development and optimization of High-Hertz stress contact to reduce future contact material cost

Reducing a total contact material cost of a connector, a high-Hertz stress with low normal force (LNF) contact will be a key technology in the future. Only an R5m tip with 0.1N force contact provides an excellent electrical performance which is much sharper than conventional connectors. 0.30 million cycles durability test was passed and the contact resistance was ≦50m-ohm