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This paper proposes a novel electrochemical etching process without the need for a metal mask or photo-resist mask. The selective electrochemical etching using laser-patterned (SEEL) copper layer process consists of three steps: electrodeposition, laser patterning, and electrochemical etching. In the SEEL copper layer process, a deposited copper layer was formed on stainless steel by an electrodeposition process. A patterned copper layer on stainless steel was formed by laser beam irradiation. A patterned copper layer serves as both a sacrificial layer and a protective mask during the electrochemical etching process. The results were observed via scanning electron microscopy and surface profiler measurement. The appropriate conditions for stable SEEL copper layer process were determined. Finally, selective electrochemical etching with various micro patterns on stainless steel was been successfully performed.

Article history: A method is proposed for the improvement of deposition reproducibility in the selective electrodeposition process using laser masking and DC voltage. Selective electrodeposition using laser masking and DC voltage can achieve a deposited layer with micro patterns. However, selective electrodeposition using laser masking and DC voltage have a critical problem: the lack of reproducibility in selective deposition. The reproducibility of selective electrodeposition can be improved by a new process that consists of laser masking, two-step electrodeposition, laser scribing, and ultrasonic cleaning. The experiments in this study show that the reproducibility of selective deposition can be successfully improved by the combination of two-step electrodeposition and laser scribing.

Secondary involvement of the gallbladder by systemic lymphoma is exceedingly rare and relapsed diffuse large B cell lymphoma of the gallbladder has not been reported. A 78-year-old man was admitted to the hospital due to epigastric pain and jaundice. His past medical history was remarkable for diagnosis with diffuse large B-cell lymphoma of the ileum 5 years ago. He underwent right hemicolectomy and three cycles of adjuvant chemotherapy and had complete remission. Abdominal computed tomography showed choledocholithiasis and focal thickening at fundus of the gallbladder. The patient underwent open cholecystectomy. Pathologic examination revealed diffuse large B-cell lymphoma. We report a case of solitary, relapsed diffuse large Bcell lymphoma of the gallbladder with literature review. Korean J Pancreatobiliary 2015;20(3):151-155

To the Editor, Microscopic polyangiitis (MPA) is characterized by the involvement of a wide range of blood vessels including arterioles, venules, and capillaries. Necrotizing glomerulonephritis and alveolar hemorrhage are commonly seen in patients with MPA, which may concomitantly or sequentially involve the nervous or musculoskeletal systems as well as other organs including the skin, heart, eyes, and intestine [1]. However, symptomatic pancreatic involvement in cases of anti-neutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis is extremely rare [2]. We herein report a case of MPA with crescentic glomerulonephritis that initially presented as acute pancreatitis. A 59-year-old Korean woman visited the Emergency Department in Presbyterian Medical Center for evaluation of epigastric pain and vomiting. She had a 20-year history of type 2 diabetes mellitus. On admission, she had a temperature of 37°C, pulse rate of 105 beats per minute, blood pressure of 140/80 mmHg, and respiratory rate of 18 breaths per minute. Her eyes were sunken, and her skin turgor was diminished. Her blood urea nitrogen and serum creatinine levels were 12.5 mmol/L (reference, 2.8 to 7.1) and 640 µmol/L (reference, 50 to 110), respectively. Her serum creatinine level 1 month earlier was 50 µmol/L. Her serum concentration of C-reactive protein was 82.9 mg/L (reference, < 3), and her serum amylase and lipase levels were 825 U/L (reference, 28 to 100) and 927 U/L (reference, 13 to 60), respectively. Alanine aminotransferase and bilirubin were normal. A routine chest X-ray showed slight haziness in the bilateral lung fields. Both kidneys exhibited mildly increased renal parenchymal echogenicity and normal size. To evaluate for possible pancreatitis, we performed abdominal computed tomography (CT), which did not show any swelling of the pancreas. Additionally, her antinuclear antibody titer was normal. Under the clinical impression of acute kidney injury due to dehydration and pneumonia, the patient underwent treatment by appropriate hydration and antibiotics, such as ceftriaxone. We considered the cause of dehydration to be acute pancreatitis. However, her renal function did not improve and her urine output decreased from 1,200 to 200 mL/day on the fourth day of admission. As a result, hemodialysis was initiated. We performed further laboratory testing including complement levels, autoantibodies, and ANCA studies. The complement C3 and C4 levels were 0.78 g/L (normal, 0.76 to 1.39) and 0.14 g/L (normal, 0.12 to 0.37), respectively. Rheumatoid factor was elevated to 53.3 kIU/L (reference, 0 to 15). ANCA was positive in a perinuclear pattern with a titer of 1:640. In the enzyme immunoassay, anti-myeloperoxidase antibody was positive, but anti-proteinase 3 antibody was negative. Anti-glomerular basement membrane antibody was also negative. Following the clinical diagnosis of MPA, the patient was started on 1 g/day of intravenous methylprednisolone (21st day of hospitalization) for 3 days, followed by 60 mg/day of oral prednisone. Intravenous cyclophosphamide (750 mg) was administered on the 27th day of admission. Following immunosuppressive therapy, the patient’s fever subsided and her serum and lipase levels returned to normal (Fig. 1). On the 30th day of admission, a percutaneous renal biopsy was performed. On light microscopy, all six glomeruli showed segmental or global sclerosis with crescents. Both cellular (2/6, 33%) and fibrous crescents (4/6, 66%) were present. Small amounts of mesangial immunoglobulin M and C3 deposits were detected by immunofluorescence microscopy (Fig. 2). Plasmapheresis was initiated on day 40, at which time the patient had been maintained on hemodialysis three to four times per week since day 4 of hospitalization. During dialysis on day 50, she complained of cough and dyspnea. A chest CT scan showed multifocal ground-glass opacities in the bilateral lungs. Laboratory examination revealed neutropenia (absolute neutrophil count of 0.1 × 109; reference, > 1.5 × 109) and elevated C-reactive protein (120 mg/L). The patient was diagnosed with pneumonia and treated with intravenous antibiotics, including teicoplanin and meropenem. Despite these interventions, the patient died of septic shock on hospital day 60. Figure 1. Following immunosuppressive therapy, the serum amylase levels and C-reactive protein (CRP) concentration returned to normal. ST, steroid; Cyc, cyclophosphamide; PP, plasmapheresis; HD, hemodialysis. Figure 2. (A) Kidney biopsy (light microscopy). The glomerulus shows global sclerosis with fibrocellular crescent formation. The interstitium shows plasma cell and lymphocyte infiltration with mild fibrosis (PAS, ×200). (B) Small amounts of mesangial immunoglobulin ... Although digestive tract involvement has been reported in 30% to 56% of patients with MPA, pancreatic involvement in MPA is extremely rare [1]. In several cases of Wegener’s granulomatosis, which is another form of ANCA-associated vasculitis, acute pancreatitis was the initial manifestation [3]. However, few cases of acute pancreatitis in patients with MPA have been reported. Iwasa and Katoh [2] and Haraguchi et al. [4] reported cases of MPA identified on autopsy as crescentic glomerulonephritis and necrotizing pancreatitis, respectively. In our case, the patient presented with acute pancreatitis on admission, which improved after immunosuppressive treatment. To our knowledge, this is the first case report of acute pancreatitis as an initial manifestation of MPA in Korea. There is no literature to date regarding the clinical significance of MPA presenting as acute pancreatitis. We hypothesize that there may be two clinical implications in treating these patients. First, we initially thought that the cause of the acute kidney injury in our patient was dehydration due to pancreatitis and treated her condition with intravenous fluid resuscitation and antibiotics. However, her renal function did not improve, and the patient was later found to have MPA. Therefore, in cases of acute kidney injury and concomitant pancreatitis, it is important to consider the possibility of ANCA-associated vasculitis. Second, we propose that MPA presenting with pancreatitis might be a more severe form of MPA. Chawla et al. [3] reported that all patients who presented initially with pancreatitis had a rapidly progressive course with fulminant progression of Wegener’s granulomatosis. Among patients with MPA, two patients with pancreatic involvement reportedly died despite clinical remission [2,4]. Therefore, more careful monitoring may be needed in patients with MPA and acute pancreatitis. Immunosuppressive treatment with corticosteroids, azathioprine, and cyclophosphamide causes cellular immune dysfunction, which facilitates infection by intracellular pathogens such as fungi, viruses, and mycobacteria. Booth et al. [5] reported that development of leukopenia and pneumonia were the two most common adverse events in patients with vasculitis on immunosuppressive therapy and were closely associated with sepsis and death. The patient described in the present case report died of sepsis secondary to pneumonia. In summary, we have reported a case of MPA with crescentic glomerulonephritis presenting initially as acute pancreatitis. In cases of acute kidney injury and concomitant acute pancreatitis, it is important to evaluate the presence of ANCA-associated vasculitis.

This paper proposes a method of selective electrochemical dissolution on the cylindrical surfaces of stainless steel shafts. Selective electrochemical dissolution was achieved via electrochemical etching using laser masking. A micropatterned recast layer was formed on the surface via ytterbium-doped pulsed fiber laser irradiation. The micropatterned recast layer could be used as a mask layer during the electrochemical etching process. Laser masking condition to form adequate mask layer on the planar surface for etching cannot be used directly on the non-planar surface. Laser masking condition changes depending on the morphological surface. The laser masking characteristics were investigated in order to form a uniform mask layer on the cylindrical surface. To minimize factors causing non-uniformity in the mask layer on the cylindrical surface, synchronized laser line scanning with a rotary system was applied during the laser masking process. Electrochemical etching characteristics were also investigated to achieve deeper etched depth, without collapsing the recast layer. Consequently, through a series process of laser masking and electrochemical etching, various micropatternings were successfully performed on the cylindrical surfaces.

In this research, the fabrication process of a super-hydrophobic metallic surface using laser ablation and electrodeposition was investigated. Re-entrant structure and surface roughness play an important role in forming a super-hydrophobic surface on intrinsically hydrophilic material. A micro pillar array with a re-entrant structure of copper on stainless steel was fabricated through a sequential process of laser ablation, insulating, mechanical polishing and electrodeposition. Spacing of the micro pillars in the array played a major role in the structure hydrophobicity that was confirmed by measuring the water contact angle. Surface morphology changed relative to the parameters of the laser ablation process and electrodeposition process. Under a gradual increase in current density during the electrodeposition process, surface morphology roughness was maximized for fabricating a super-hydrophobic surface. Finally, the super-hydrophobic surface was successfully fabricated on metal.

Rothia muciliaginosa (R. mucilaginosa) is a facultative, Gram-positive coccus that is considered to be part of the normal flora of the mouth and respiratory tract. There are sporadic reports of the organism causing endocarditis in patients with heart valve abnormalities, as well as meningitis, septicemia, and pneumonia associated with intravenous drug abuse. However, it is an unusual pathogen in cases of peritoneal dialysis (PD)-associated peritonitis. Although R. mucilaginosa is generally susceptible to penicillin, ampicillin, cefotaxime, imipenem, rifampicin, and glycopeptides, there are no guidelines for the treatment of PD-associated peritonitis. Herein, we report a case of PD-associated peritonitis due to R. mucilaginosa that was resolved with intraperitoneal antibiotic treatment.

This paper proposes a novel selective metal deposition process that uses a combination of laser irradiation and electrodeposition. Via the selective electrodeposition using laser irradiation (SELI) process, metal can be deposited selectively on a metal surface without a special mask, which is in contrast to conventional deposition processes that routinely require a metal mask or a photo-resist. The SELI process consists of three steps: laser irradiation, electrodeposition, and ultrasonic vibration cleaning. In the course of experimentation, a recast layer was formed via the laser irradiation process, which acts as the sacrificial layer in the SELI process. The sacrificial layer was removed after the cleaning step. The separation of the sacrificial layer was due to the hydrogen evolution effects of the hydrogen embrittlement via the hydrogen bubbles and the hydrogen absorption. The results were observed via focused ion beam (FIB) analysis of the cross-sectional images. Electron probe X-ray micro-analyzer (EPMA) analysis was used to detect the surface components. Through the SELI process, selective copper deposition was successfully performed with various micro-patterns of the approximately 4 μm thick deposited copper.

Micro electrochemical machining (ECM) of tungsten carbide with cobalt binder (WC–Co) was studied using ultrashort pulses. In ECM, the machining characteristics were investigated according to machining conditions such as electrolyte, workpiece potential, and applied voltage pulse. Using a mixture of sulfuric acid and nitric acid, microstructures with a sharp edge and good surface quality were machined on tungsten carbide alloy. The potentials of workpiece electrode and tool electrode were determined by considering the machining rate, machining stability, and surface quality of products. With the negative potential of the workpiece electrode, oxide formation was successfully prevented and shape with good surface quality in the range from Ra 0.069 μm to 0.075 μm were obtained by electrochemical machining. Moreover, the performance of ECM, which includes machining gap, tapering, surface roughness, and machining time, without tool wear was compared with that of electrical discharge machining (EDM). Microstructures of WC–Co with a sharp edge and good surface quality were obtained by electrochemical milling and electrochemical drilling. Micro electrochemical turning was also introduced to fabricate micro shafts.

In this paper, a micro-pin array with a high aspect ratio was fabricated on AISI 304 using laser beam ablation for attachment to a vertical wall. In recent times, there has been research in various fields, including robotics and bio-MEMS, regarding attachment to vertical walls, and micro-pin arrays may offer the best solution. For vertical wall attachment, the micro-pin should have a high aspect ratio, long length, and sharp tip. The recast layer could be piled due to the chromium oxide with high surface tension and viscosity of chromium oxide, and it composed the micro-pins with high aspect ratio. X-ray photoelectron spectroscopy (XPS) was used to identify the characteristics of the piled recast layer. The machining characteristics for a high aspect ratio micro-pin array were investigated according to laser beam machining parameters. In addition, experiments for attaching force relative to the surface roughness of the subject plane were carried out.

The characteristics of the prevention of electrolytic corrosion during micro electrical discharge machining (EDM) using deionized water and high frequency bipolar pulse were investigated. Electrolytic corrosion during micro EDM using deionized water was analyzed using an equivalent electrical circuit based on the electrical double layer theory. Based on the analysis and experimental verification, a narrow positive pulse duration should be provided to the workpiece to prevent corrosion. A negative voltage with zero average applied voltage (Vavg, app) is also essential for this purpose. If Vavg, app is positive or negative, electrolytic corrosion occurs on the workpiece or tool, respectively. Micro holes and 3D structures without corrosion were successfully fabricated using a high frequency bipolar pulse with a pulse duration of 0.2 μs and a period of 1 μs, as well as Vavg, app = 0 V.

Electrochemical etching using laser masking (EELM), which is a combination of laser beam irradiation for masking and electrochemical etching, allows the micro fabrication of stainless steel without photolithography technology. The EELM process can produce various micro patterns and multilayered structures. In this study, the machining characteristics of EELM were investigated. Changes in characteristics of recast layer formation and the protective effect of the recast layer according to the laser masking conditions and electrochemical etching conditions were investigated by field emission scanning electron microscopy (FE-SEM), focused ion beam (FIB) and X-ray photoelectron spectroscopy (XPS). The oxidized recast layer with a thickness of 500 nm was verified to yield a superior protective effect during electrochemical etching and good form accuracy. Finally, micro patterns and structures were fabricated by EELM.

Electrolytic corrosion occurs if water is used as a dielectric fluid during micro EDM process, ultimately resulting in serious inaccuracies on a machined part. In order to prevent electrolytic corrosion, a high frequency AC power source was developed for micro wire EDM processes. This study presents an analysis based on the electrical double layer theory. Based on this theory, the effects of electrolytic corrosion decrease as the AC power source frequency increases. As an anticorrosion power source, a 13.56 MHz AC power source was developed using class E power amplifier. This new power source produced discharge current pulses with a peak of 1.1 A and a duration of 20 ns. With the new power source, micro shafts were successfully machined by micro wire EDM using tap water without exhibiting electrolytic corrosion. In comparison to a conventional RC type power source, the high frequency AC power source with tap water ensured 7 times higher material removal rate while maintaining similar surface roughness (< 0.1 μm Ra).

Micro EDM using conventional pulse generators such as the RC type or transistor type with water as the dielectric fluid suffers from poor accuracy of machined structures due to electrolytic corrosion. In this study, a new high frequency bipolar pulse generator for micro EDM in water was developed in order to prevent electrolytic corrosion. The new pulse generator produced a high frequency bipolar pulse possessing a positive pulse duration of several hundred nanoseconds with a high repetition rate provided to the machining gap. Discharge characteristics of micro EDM using the new pulse generator were investigated. Machining characteristics were also investigated according to machining conditions such as the repetition rate, positive voltage, capacitance and resistivity. Using the new pulse generator, micro holes without electrolytic corrosion were successfully fabricated in deionized water and tap water. Machining time, tool wear and clearance using the new pulse generator in deionized water decreased compared with those using the RC circuit in kerosene.

The demand for micro parts and moulds has been increasing in various fields. Among the various micro machining technologies, micro electrical machining is one of the most widely used because it can be applied for conductive or nonconductive materials. This paper discusses the recent studies that explore many ways to improve micro electrical machining performance. Many researchers proposed ways to improve productivity and accuracy through experimental or analytical studies. The improved-performance trends of micro electrical machining are expected to continue thanks to the miniaturization of manufactured goods in a high-tech industry.

Surface texturing with micro-dimples is a known method for friction reduction under lubricated sliding contact, and various machining techniques have been researched and developed in order to fabricate micro-dimple patterns. However, previous fabrication methods possess several problems, such as causing thermal damage on the workpiece or limiting the available workpiece geometry. In micro ECM, micro features can be machined without any resulting thermal or mechanical damage. From this perspective, micro ECM has certain advantages over surface texturing. Also, micro ECM is applicable to non-planar workpieces. In this research study, micro ECM with microsecond pulses was applied in order to fabricate a micro-dimple pattern. The machining characteristics were investigated in fabricating micro dimples on AISI 440C specimen. On the basis of the experimental results, a O 300 μm dimple pattern was successively produced on the AISI 440C specimen. A friction test on the textured specimen was performed and compared with a non-textured specimen. The enhancement of frictional performance was successfully demonstrated experimentally.

This paper proposes a novel process for electrochemical etching of metal without a need for photo-mask. Electrochemical etching using laser masking (EELM) process includes laser masking and anodic dissolution. In the laser masking step, a patterned layer on a stainless steel surface was formed by laser marking using a pulsed fiber laser. This patterned surface was selectively dissolved during the electrochemical etching step because the laser marked area temporarily acted as a protective mask. To fabricate microstructures, the appropriate conditions for stable EELM process were determined. Consequently, multilayered structures were successfully achieved by recursive EELM process without any requirement for a photo-lithography process.

In micro electrochemical machining(micro-ECM), it is important to measure and control the potential of a tool electrode and a workpiece electrode because electrochemical reaction rate depends on the potential of the electrodes. When the electrode potential was measured against a reference electrode, the error of measured electrode potential could be minimized by proper tool electrode design. In this paper, multi-function electrodes consisting of a tool electrode and a reference electrode was fabricated by micro fabrication techniques. The machining conditions in micro-ECM using multi-function electrodes, such as pulse voltage parameters and electrode potential, were investigated.

Micromachining of internal features by electrochemical machining (ECM) is investigated. By controlling pulse conditions and using a customized tool electrode, micro features were machined on the side wall of a micro hole. In micro ECM, longer pulse on-time enlarges the side gap. A reverse tapered hole and a barrel-shape hole were fabricated through pulse duration control. Micro cavity was machined by controlling the pulse duration and machining time in similar manner. A micro disk-shape electrode was used to machine microgroove inside the hole, which is similar to turning lathe process.

A new micro patterning process without the need for a mask is proposed in this paper. It is a combination of laser masking and electrochemical etching. In electrochemical etching through laser masking (EELM), selective electrochemical dissolution of stainless steel is achieved in a 2 M sodium nitrite electrolyte. The micro-patterned surface layer of stainless steel is formed by laser marking using an ytterbium pulsed fiber laser. After the laser masking process, the patterned surface of stainless steel is selectively dissolved under an appropriate electrochemical etching condition because the laser-marked area can temporarily act as a barrier during electrochemical etching. The characteristics of the laser-marked surfaces have been investigated by scanning electron microscopy (SEM), x-ray diffractometry (XRD) and x-ray photoelectron spectroscopy (XPS). The polarization curve has been used to evaluate electrochemical dissolution behaviors. The EELM process enables the electrochemical micro-machining of stainless steel without photolithography technology; thus, it can be applied in micro fabrication, micro patterning and surface texturing.

Micro electrical discharge machining (micro EDM) is a well-known precise machining process that achieves micro structures of excellent quality for any conductive material. However, the slow machining speed and high tool wear are main drawbacks of this process. Though the use of deionized water instead of kerosene as a dielectric fluid can reduce the tool wear and increase the machine speed, the material removal rate (MRR) is still low. In contrast, laser ablation using a nanosecond pulsed laser is a fast and non-wear machining process but achieves micro figures of rather low quality. Therefore, the integration of these two processes can overcome the respective disadvantages. This paper reports a hybrid process of a nanosecond pulsed laser and micro EDM for micromachining. A novel hybrid micromachining system that combines the two discrete machining processes is introduced. Then, the feasibility and characteristics of the hybrid machining process are investigated compared to conventional EDM and laser ablation. It is verified experimentally that the machining time can be effectively reduced in both EDM drilling and milling by rapid laser pre-machining prior to micro EDM. Finally, some examples of complicated 3D micro structures fabricated by the hybrid process are shown.

In this paper, with the use of deionized water, a finishing process of micro hole surfaces processed by micro electrical discharge machining (micro-EDM) is investigated. A micro hole is machined by micro-EDM using deionized water as a dielectric fluid. The inner surface of the hole is finished successfully via electrochemical dissolution in deionized water. The effects of finishing conditions such as the resistivity of deionized water, the voltage, the tool rotation and the finishing time on the surface quality and accuracy of the shape were investigated. After a finishing process using deionized water with a resistivity of 2 MΩ cm, a voltage of 80 V, a tool rotation of 1200 rpm and a finishing time of 6 min, the surface roughness was reduced considerably from 0.225 µm Ra after micro-EDM to 0.066 µm Ra.