Activation of sphingomyelinase (SMase) by extracellular stimuli is the major pathway for cellular production of ceramide, a bioactive lipid mediator acting through sphingomyelin (SM) hydrolysis. Previously, we reported the existence of six forms of neutral pH–optimum and Mg2+-dependent SMase (N-SMase) in the membrane fractions of bovine brain. Here, we focus on N-SMase ε from salt-extracted membranes. After extensive purification by 12,780-fold with a yield of 1.3%, this enzyme was eventually characterized as N-SMase2. The major single band of 60-kDa molecular mass in the active fractions of the final purification step was identified as heat shock protein 60 (Hsp60) by matrix-assisted laser desorption/ionization time-of-flight mass spectrometric analysis. Proximity ligation assay and immunoprecipitation study showed that Hsp60 interacted with N-SMase2, prompting us to examine the effect of Hsp60 on N-SMase2 and ceramide production. Interestingly, Hsp60 siRNA treatment significantly increased the protein level of N-SMase2 in N-SMase2-overexpressed HEK293 cells. Furthermore, transfection of Hsp60 siRNA into PC12 cells effectively increased both N-SMase activity and ceramide production and increased dopamine re-uptake with paralleled increase. Taken together, these results show that Hsp60 may serve as a negative regulator in N-SMase2-induced dopamine re-uptake by decreasing the protein level of N-SMase2.

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We estimated the process margins of various cell structures and process problems for full chip process under extreme resolution limit of exposure tool. Therefore, optimizing off axis illumination (OAI) condition for various structures obtained the fme pattern and wider process margin using simulation and experiment. From our experiment, we should use as higher numerical aperture (NA), smaller R and smaller r as possible to reduce critical dimension (CD) difference between dense and isolated patterns. Process margins are obtained more than 8% exposure latitude (EL) and 0.5 tin depth of focus (DOF) for each cell. However, we can consider using of attenuated phase shift mask (PSM) to improve the exposure and DOF margin. We fmd that real full chip process induces the critical problems such as isolated line (I/L) and space (L'S) pattern variation due to lens aberration, partial coherence effect, mask error effect, and optical proximity effect. These effects play a role to determine the design rule of cell and periphery structures. In spite of good lens quality, variation of I/L and US pattern for various exposure conditions is almost 4Onm or more compared to line and space (L/S) pattern. These phenomena are becoming the critical issue to fulfill the full chip process of l3Onm lithography. By optimizing mask error effect, isolated and dense pattern bias (ID bias), and OAI, we can achieve l3Onm technology with 248nm KrF lithography.

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To achieve lOOnm DRAM full chip with O.63NA ArF lithography we used a new type of off-axis illumination, crosspole illumination which has four poles on axis. For lower than 0.33 k1 process double exposure technology has been introduced which is exposing cell and core/periphery region separately with different illumination conditions. But with crosspole 0.33 to 0.3 1 k1 process could be possible without double exposure. Advantages and disadvantages of crosspole illumination and successful result of printing lOOnm DRAM full chip are shown in this paper. And also ArF lithography issues occurred during processing DRAM full chip are reported such as lens heating, contamination optics and reticles, overlay errors induced by electron beam curing process and so on. To simulate patterning result we used HOST(Hynix OPC simulation tool) based on diffused aerial image model(DAIM). For all kinds of lOOnm DRAM patterns, we could get sufficient process latitude, more than 10% exposure latitude(EL) and 0.4 jiiii depth of focus(DOF). Also 95nm DRAM cell patterns could be printed successfully with crosspole single exposure and this shows with 0.75NA and 0.85NA ArF tools we can print 8Onm and 7Onm DRAM patterns, respectively.