Greater Leakage Research Articles

Comparative Evaluation of Microleakage and Shear Bond Strength of Glass Ionomer Cement, Composite, Resin Modified Glass Ionomer Cement Restorative Material: An In Vitro Study

Aim: Evaluation of microleakage and shear bond strength of glass ionomer cement, composite, resin modified glass ionomer Cement Restorative Material. Material and Method: Thirty freshly extracted non carious teeth, free of cracks and restorations, collected for the present in-vitro study. Teeth were divided in three equal group i.e. group A: Glass Ionomer Cement. Group B: Resin Modified Glass Ionomer Cement, Group C: Composite Resin. All groups' shear bond strengths were evaluated using a universal testing machine. A rod in the shape of a chisel was positioned close to the bonded restorative material and directly next to the flat dentinal surface. To debond the material, a cross head of universal testing machine at a speed of 0.5mm/min was employed. Then, Mega Pascal Units (MPa) were used to calculate the shear bond strength. To evaluate the microleakage two coats of nail polish were applied to the samples, leaving a 1 mm window around the cavity boundaries. A wet cotton pellet was placed over the restoration to avoid desiccation while the nail polish was being applied. Inverted teeth were submerged for 24 hours at 37°C under vacuum in a solution of 2% Rhodamine-B dye. Only the coronal part of the teeth were dyed to avoid dye leakage via the root apices. The surface-adhered dye was washed off the specimens in tap water after removing them from the dye solution, and nail polish was then removed with a BP blade. The teeth were sectioned longitudinally in a bucco-lingual direction through the center of the restorations using a water-cooled low-speed diamond disc. The section with the greater leakage was evaluated with a stereomicroscope at ×25 magnification to determine the extent of dye penetration at the occlusal and gingival margins by two evaluators who were blinded to the experimental groups. Result: Composite resin showed highest shear bond strength followed by Bond Strength of Resin Modified Glass Ionomer Cement and least with conventional glass ionomer cement. Microleakage was found lower in composite resin as compared to Resin modified glass ionomer cement and glass ionomer cement. Conclusion: It can be stated that Composite resin and Resin modified glass ionomer cement have good shear bond strength and lower microleakage as compared to Glass Ionomer Cement.

Effect of a soluble subgrade on leakage through a geomembrane defect

Leakage and erosion of a soluble subgrade overlain by a geomembrane with a 70-mm-long slit defect is examined. The subgrade (gypsum) solubility and its rate of dissolution from a solid state in contact with various solutions are investigated. In the absence of flow, the rate of dissolution is negligible. However, when there is flow there is dissolution, and if the flow is high enough, erosion. Erosion greatly increases fluid migration. The presence of an interface between the subgrade and a dissimilar material (e.g. a geomembrane) facilitates flow, dissolution, and erosion as the interface becomes an ever increasing preferential flow path, leading to a much greater leakage and erosion feature. The findings from this study highlight the risk of having a soluble subgrade below a single geomembrane used alone and exposed for the containment of liquids.

Making the EU Carbon Border Adjustment Mechanism acceptable and climate friendly for least developed countries

Implementation of CBAM to support EU climate neutrality by 2050 has raised several concerns. As the mechanism aims to minimise leakage through equal fairness in global mitigation, imposing carbon tariffs on the EU’s imports of energy-intensive goods could curtail the export of EU trading partners. This might be detrimental, especially to the LDCs, due to their high exposures and vulnerability risks. This paper assesses and quantifies the implication of EU-CBAM and analyses eight complementary measures to mitigate the impacts on LDCs. Scenario developments are constructed by projecting the EU’s new climate targets relative to the reference scenario of the EU’s current policies. A more stringent climate target results in carbon leakage, and implementing CBAM will reduce the rate by one-third by 2040. The analysis also confirms significant welfare loss for LDCs through declining exports. Exempting LDCs from EU CBAM is less justifiable, as this measure results in greater leakage than other options. A further assessment confirms that policy recommendation for CBAM complementary measures should focus on the climate transformation pathway for LDCs. EU CBAM implementation with revenue-redistribution targeted to promote clean and efficient use of energy in LDCs has improved the welfare of recipient countries, substantially reduced leakage, and proven cost-efficient for the EU.

Potential Impact of Reactor Core Damage on Severe Accident Management Actions in Vicinity of Spent Fuel Pool

Fukushima Daiichi NPP accident showed that plant technical support center (TSC) in an extreme and rare external event (design extended condition (DEC)) can have a problem in the case of coincident loss of decay heat removal from the core (possibly resulting in significant core damage) and loss of decay heat removal from spent fuel pool. From the point of view of prioritizing severe accident management strategies it looks like the priority mitigation action should be to reestablish the emergency core cooling in the reactor pressure vessel. The reason is the longer time window available before the water inventory in the spent fuel pool would be evaporated and spent fuel exposed to overheating. However, if such actions would not be successful and reactor core would, consequently, be damaged, potential design basis leakage (or even greater leakage) from the containment to the fuel handling building (FHB) can affect already established TSC measures or operator accessibility to FHB, or it can jeopardize functioning of the systems, structures and components due to radioactive releases and presence of hydrogen (independently of the fact that containment atmosphere can be inerted by steam or that containment may be equipped with passive autolytic recombiners (PARs)). Paper describes an engineering evaluation of possible hydrogen presence in the containment annulus, its flammability and leakages through the penetrations toward FHB in the case of long term station blackout (SBO) without successful restoration of the core cooling in the reactor pressure vessel. SBO accident sequence progression and amount of produced hydrogen is evaluated by MAAP code.

Thermal profiles reveal stark contrasts in properties of biological membranes from heart among Antarctic notothenioid fishes which vary in expression of hemoglobin and myoglobin

Antarctic notothenioids are noted for extreme stenothermy, yet underpinnings of their thermal limits are not fully understood. We hypothesized that properties of ventricular membranes could explain previously observed differences among notothenioids in temperature onset of cardiac arrhythmias and persistent asystole. Microsomes were prepared using ventricles from six species of notothenioids, including four species from the hemoglobin-less (Hb-) family Channichthyidae (icefishes), which also differentially express cardiac myoglobin (Mb), and two species from the (Hb+) Nototheniidae. We determined membrane fluidity and structural integrity by quantifying fluorescence depolarization of 1,6-diphenyl-1,3,5-hexatriene (DPH) and leakage of 5(6)-carboxyfluorescein, respectively, over a temperature range from ambient (0°C) to 20°C. Compositions of membrane phospholipids and cholesterol contents were also quantified. Membranes from all four species of icefishes exhibited greater fluidity than membranes from the red-blooded species N. coriiceps. Thermal sensitivity of fluidity did not vary among species. The greatest thermal sensitivity to leakage occurred between 0 and 5°C for all species, while membranes from the icefish, Chaenocephalus aceratus (Hb-/Mb-) displayed leakage that was nearly 1.5-fold greater than leakage in N. coriiceps (Hb+/Mb+). Contents of phosphatidylethanolamine (PE) were approximately 1.5-fold greater in icefishes than in red-blooded fishes, and phospholipids had a higher degree of unsaturation in icefishes than in Hb+notothenioids. Cholesterol contents were lowest in Champsocephalus gunnari (Hb-/Mb-) and highest in the two Hb+/Mb+species, G. gibberifrons and N. coriiceps. Our results reveal marked differences in membrane properties and indicate a breach in membrane fluidity and structural integrity at a lower temperature in icefishes than in red-blooded notothenioids.

New Leakage Model for Naturally Fractured Formations Considering the Effects of Dual-System Hydro-Mechanical Coupling

Within the existing leakage model accounting for drilling mud loss in naturally-fractured formations, the leak-off velocity is assigned to a fixed value or described by the Cater model, which does not consider the influence of dual-system hydromechanical coupling effects between fracture-wall and fracture-inner systems. The dual-system between the formation and fracture is controlled by the flowing net pressure inside the fracture, which determines the dynamic width of the natural fracture and leak-off velocity. In this study, first, the leak-off velocity under the hydromechanical coupling of the fracture-wall system was obtained based on the coupled governing equations of the solid and liquid phases of the natural fracture-wall, as well as Darcy’s law. Second, the leakage-front invasion velocity, leakage rate, and leakage volume under the hydromechanical coupling of the fracture-inner system were clarified according to the geometric governing of the natural fracture morphology. Finally, the dual-system coupling leakage model was developed considering the continuous equation, while the numerical solution was obtained through a time-step deduction. Results show that at a given time, a greater formation permeability leads to a greater leakage rate and volume, with a smaller leakage front distance. The leakage rate increases with an increase in formation permeability, well bottom differential pressure, and initial width of the natural fracture, while it decreases with an increase in the fracture normal stiffness, yield stress, and plastic viscosity. The new leakage model and numerical method concerning time-step deduction are assessed by solving the issues of fully coupled fracture-wall and fracture-inner systems considering drilling fluid leak-off. The new model may be utilized to simulate various problems related to the invasion of drilling fluids into the fractures, including predicting the dynamic width of natural fracture and borehole ballooning/breathing phenomena.

Analytical model of leakage through an incomplete-sealed well

This study presents a new analytical model to predict the pressure changes in a monitoring well and the leakage rate due to the leakage through an incomplete-sealed well in a closed system. Different from previous analytical models, herein we develop a new model to simulate the leakage of a leaky well which is incomplete-sealed and connects with the storage aquifer in a certain segment. Based on the problem description and assumptions, the governing equations with corresponding definite conditions are presented and solved by means of Laplace transform, Fourier cosine transform and Duhamel's principle. Verification of the developed model is achieved by comparing with existing analytical model. Then, the leakage rates and pressure changes are calculated for different key factors and sensitivity analyses are conducted. Obviously, a higher permeability accelerates the fluid exchange between the storage aquifer and the monitoring aquifer. Thus, with the increase of the leakage permeability, the leakage from the storage aquifer is more intensive but the ultimate leakage rate is invariable. With the decrease of the dimensionless distance, the seepage resistance along the leakage path is decreasing, resulting in the greater leakage between the two aquifers. Similarly, the dynamic equilibrium is unaffected by the position of the leakage segment. The incomplete seal of the leaky well only affects the spherical flow stage and this effect is relatively small. Therefore, the dimensionless leakage height has no obvious effect on the leakage. The increase of the storativity ratio enlarges the pressure difference between the two aquifers and increases the ultimate leakage rate to achieve the dynamic equilibrium. The leakage in the case with greater storativity ratio increases more significantly. This paper presents a simple and efficient analytical solutions for the leakage through an incomplete-sealed well and extends the applicability of the previous models.

Reaction-diffusion memory unit: Modeling of sensitization, habituation and dishabituation in the brain.

We propose a novel approach to investigate the effects of sensitization, habituation and dishabituation in the brain using the analysis of the reaction-diffusion memory unit (RDMU). This unit consists of Morris-Lecar-type sensory, motor, interneuron and two input excitable cables, linked by four synapses with adjustable strength defined by Hebbian rules. Stimulation of the sensory neuron through the first input cable causes sensitization by activating two excitatory synapses, C1 and C2, connected to the interneuron and motor neuron, respectively. In turn, the stimulation of the interneuron causes habituation through the activation of inhibitory synapse C3. Likewise, dishabituation is caused through the activation of another inhibitory synapse C4. We have determined sensitization-habituation (BSH) and habituation-dishabituation (BHDH) boundaries as functions between synaptic strengths C2 and C3 at various strengths of C1 and C4. When BSH and BHDH curves shift towards larger values of C2, the RDMU can be easily inhibited. On the contrary, the RDMU can be easily sensitized or dishabituated if BSH and BHDH curves shift towards smaller values of C2. Our numerical simulations readily demonstrate that higher values of the Morris-Lecar relaxation parameter, greater leakage and potassium conductances, reduced length of the interneuron, and higher values of C1 all result in easier habituation of the RDMU. In contrast, we found that at higher values of C4 the RDMU becomes significantly more prone to dishabituation. Based on these simulations one can quantify BSH and BHDH curve shifts and relate them to particular neural outcomes.

Low‐leakage current two‐stage transformerless grid‐connected converter for residential PV application

Conventional PV-fed three-level DC-DC converter has greater leakage current due to varying common mode (CM) voltage, and thus requires galvanic isolation if interfaced with on-grid inverters. To reduce the leakage current and eliminate the requirement of galvanic isolation, a low-leakage three-level DC-DC converter is proposed for residential application. Efficacy of the converter is demonstrated by proposing a two-stage single-phase on-grid PV system by interfacing with a three-level transformerless single-phase inverter topology. The DC-DC converter has reduced leakage current, which decreases the overall leakage current in the PV inverter system. In addition, smaller filter magnetics are required for both the three-level converter and three-level inverter. The CM analysis of the proposed system is presented. The proposed system is simulated using PSCAD and a laboratory prototype is developed for experimental evaluation. The experimental results show a part-load efficiency of >96% for the overall system. Furthermore, the measured leakage current in the proposed system is <;10 mA, which is below the prescribed RMS limit, as specified in German DIN VDE 0126-1-1 standard.

Influence of Oxygen Pressure on the Domain Dynamics and Local Electrical Properties of BiFe0.95Mn0.05O₃ Thin Films Studied by Piezoresponse Force Microscopy and Conductive Atomic Force Microscopy.

In this work, we have studied the microstructures, nanodomains, polarization preservation behaviors, and electrical properties of BiFe0.95Mn0.05O3 (BFMO) multiferroic thin films, which have been epitaxially created on the substrates of SrRuO3, SrTiO3, and TiN-buffered (001)-oriented Si at different oxygen pressures via piezoresponse force microscopy and conductive atomic force microscopy. We found that the pure phase state, inhomogeneous piezoresponse force microscopy (PFM) response, low leakage current with unidirectional diode-like properties, and orientation-dependent polarization reversal properties were found in BFMO thin films deposited at low oxygen pressure. Meanwhile, these films under high oxygen pressures resulted in impurities in the secondary phase in BFMO films, which caused a greater leakage that hindered the polarization preservation capability. Thus, this shows the important impact of the oxygen pressure on modulating the physical effects of BFMO films.

Radiation leakage dose from Elekta electron collimation system.

This study provided baseline data required for a greater project, whose objective was to design a new Elekta electron collimation system having significantly lighter electron applicators with equally low out‐of field leakage dose. Specifically, off‐axis dose profiles for the electron collimation system of our uniquely configured Elekta Infinity accelerator with the MLCi2 treatment head were measured and calculated for two primary purposes: 1) to evaluate and document the out‐of‐field leakage dose in the patient plane and 2) to validate the dose distributions calculated using a BEAMnrc Monte Carlo (MC) model for out‐of‐field dose profiles. Off‐axis dose profiles were measured in a water phantom at 100 cm SSD for 1 and 2 cm depths along the in‐plane, cross‐plane, and both diagonal axes using a cylindrical ionization chamber with the 10×10 and 20×20 cm2 applicators and 7, 13, and 20 MeV beams. Dose distributions were calculated using a previously developed BEAMnrc MC model of the Elekta Infinity accelerator for the same beam energies and applicator sizes and compared with measurements. Measured results showed that the in‐field beam flatness met our acceptance criteria (±3% on major and ±4% on diagonal axes) and that out‐of‐field mean and maximum percent leakage doses in the patient plane met acceptance criteria as specified by the International Electrotechnical Commission (IEC). Cross‐plane out‐of‐field dose profiles showed greater leakage dose than in‐plane profiles, attributed to the curved edges of the upper X‐ray jaws and multileaf collimator. Mean leakage doses increased with beam energy, being 0.93% and 0.85% of maximum central axis dose for the 10×10 and 20×20 cm2 applicators, respectively, at 20 MeV. MC calculations predicted the measured dose to within 0.1% in most profiles outside the radiation field; however, excluding modeling of nontrimmer applicator components led to calculations exceeding measured data by as much as 0.2% for some regions along the in‐plane axis. Using EGSnrc LATCH bit filtering to separately calculate out‐of‐field leakage dose components (photon dose, primary electron dose, and electron dose arising from interactions in various collimating components), MC calculations revealed that the primary electron dose in the out‐of‐field leakage region was small and decreased as beam energy increased. Also, both the photon dose component and electron dose component resulting from collimator scatter dominated the leakage dose, increasing with increasing beam energy. We concluded that our custom Elekta Infinity with the MLCi2 treatment head met IEC leakage dose criteria in the patient plane. Also, accuracy of our MC model should be sufficient for our use in the design of a new, improved electron collimation system.PACS number(s): 87.56.nk, 87.10.Rt, 87.56.J

Altered geosynthetic clay liners: effect on the hydraulic performance of composite liners

This study evaluates how alteration of geosynthetic clay liners (GCLs) affects the hydraulic behaviour of a composite liner when the geomembrane presenting a hole is overlying a GCL. Interface transmissivity experiments were performed on GCL specimens that were exhumed from field sites. The results reveal different trends in the flow rates, which decrease differently to their steady state values. The steady state flow rates obtained and the calculated interface transmissivities are of the same order of magnitude as results obtained with a virgin GCL. The transient flow rate results are discussed in relation with the GCLs parameters. Based on these results, a new equation is derived that links interface transmissivity to the hydraulic conductivity of GCLs that have been altered by the environment. Considering large transient flow rates in calculations result in a greater leakage volume penetrating the liner when compared to calculations of infiltrated volumes considering only steady state leakage volume for a period of time of 1, 10 or 30 years. From a practical point of view, this suggests the introduction of a factor of safety of 1.67 when calculating the flow rate in composite liners in order to take into account the alteration by the environment of GCLs.

A Blocking-Aware Scheduling for Real-Time Task Synchronization Using a Leakage-Controlled Method

Due to the importance of power dissipation in the wireless sensor networks and embedded systems, real-time scheduling has been studied in terms of various optimization problems. Real-time tasks that synchronize to enforce mutually exclusive access to the shared resources could be blocked by lower priority tasks. While dynamic voltage scaling (DVS) is known to reduce dynamic power consumption, it causes increased blocking time due to lower priority tasks that prolong the interval over which a computation is carried out. Additionally, processor slowdown to increase execution time implies greater leakage energy consumption. In this paper, a leakage-controlled method is proposed, which decreases both priority inversion and power consumption. Based on priority ceiling protocol (PCP) and a graph reduction technique, this method can decrease more energy consumption and avoid priority inversion for real-time tasks.

Role of Nanoparticle Surface Functionality in the Disruption of Model Cell Membranes

Lipid bilayers are biomembranes common to cellular life and constitute a continuous barrier between cells and their environment. Understanding the interaction of engineered nanomaterials (ENMs) with lipid bilayers is an important step toward predicting subsequent biological effects. In this study, we assess the effect of varying the surface functionality and concentration of 10-nm-diameter gold (Au) and titanium dioxide (TiO(2)) ENMs on the disruption of negatively charged lipid bilayer vesicles (liposomes) using a dye-leakage assay. Our findings show that Au ENMs having both positive and negative surface charge induce leakage that reaches a steady state after several hours. Positively charged particles with identical surface functionality and different core compositions show similar leakage effects and result in faster and greater leakage than negatively charged particles, which suggests that surface functionality, not particle core composition, is a critical factor in determining the interaction between ENMs and lipid bilayers. The results suggest that particles permanently adsorb to bilayers and that only one positively charged particle is required to disrupt a liposome and trigger the leakage of its entire contents in contrast to mellitin molecules, the most widely studied membrane lytic peptide, which requires hundred of molecules to generate leakage.

Unequal access to analyst research

This study examines the relationship between equity analysts and information asymmetry, and the extent of leakages in analyst recommendations. Literature suggests that analysts reduce information asymmetry by bringing privately held information to the market, and through superior analysis of publicly available information. However, we find that investor access to analyst reports is far from even, and show evidence consistent with the leakage of analyst recommendations. We find that leakages provide annualised cumulative abnormal returns of approximately 6.30% for upgrades and 12.53% for downgrades over a four-week period, after a generous provision of 1% (round trip) for transaction costs. In our examination of broker/analyst size, we find evidence of greater leakage from the smaller brokers on stock downgrades, but not upgrades. We suggest that smaller brokers are less likely to have an established relationship with company management, are less reliant on them as a source of future information, and are therefore less hesitant to leak downgrades.

Assessment of leakage doses around the treatment heads of different linear accelerators

Out-of-field doses to untargeted organs may have long-term detrimental health effects for patients treated with radiotherapy. It has been observed that equivalent treatments delivered to patients with different accelerators may result in significant differences in the out-of-field dose. In this work, the points of leakage dose are identified about the gantry of several treatment units. The origin of the observed higher doses is investigated. LiF:Mg,Cu,P thermoluminescent dosimetry has been employed to quantify the dose at a several points around the linac head of various linear accelerators (linacs): a Varian 600C, Varian 21-iX, Siemens Primus and Elekta Synergy-II. Comparisons are also made between different energy modes, collimator rotations and field sizes. Significant differences in leaked photon doses were identified when comparing the various linac models. The isocentric-waveguide 600C generally exhibits the lowest leakage directed towards the patient. The Siemens and Elekta models generally produce a greater leakage than the Varian models. The leakage 'hotspots' are evident on the gantry section housing the waveguide on the 21-iX. For all machines, there are significant differences in the x and y directions. Larger field sizes result in a greater leakage at the interface plate. There is a greater leakage around the waveguide when operating in a low-energy mode, but a greater leakage for the high-energy mode at the linac face. Of the vendors investigated, the Varian 600C showed the lowest average leakage dose. The Varian 21-iX showed double the dose of the 600C. The Elekta Synergy-II had on average four times the dose leakage than the 600C, and the Siemens Primus showed an average of five times that of the 600C. All vendors show strong differences in the x and y directions. The results offer the potential for patient-positioning strategies, linac choice and shielding strategies to reduce the leakage dose to patients.

Angiostatic Effect of CXCR3 Expressed on Choroidal Neovascularization

Several recent studies suggest that some chemokines/chemokine receptors are involved in choroidal neovascularization (CNV). CXCR3 was the focus of the present study because microarray analysis for murine laser-induced CNV model showed the increased expression of CXCR3. The purpose of this study was to evaluate the effect of CXCR3 on CNV. Microarray analysis was performed for the mouse eyes with laser-induced CNV. CXCR3 expressions on the CNV were evaluated by immunohistochemistry and real-time RT-PCR. CNV was compared between CXCR3-deficient mice and wild-type mice, between mice treated with anti-CXCR3/anti-IP-10 neutralizing antibody and mice treated with control IgG. Macrophage recruitment into CNV was also investigated. Ocular expressions of vascular endothelial growth factor (VEGF), pigment epithelium-derived factor (PEDF), C-C chemokine ligand-2 (CCL2), and complement component-3 (C3) were evaluated by real-time PCR. Microarray analysis and real-time RT-PCR revealed the elevation of CXCR3 and IP-10 in laser-treated mouse eyes compared with control eyes. Immunohistochemistry showed CXCR3 expression on the endothelial cells of CNV. Laser-induced CNV of CXCR3-deficient mice was significantly larger, with greater leakage in fluorescein angiography, and with greater macrophage-infiltration compared with wild-type mice (P < 0.01). Intravitreal injection of anti-CXCR3/anti-IP-10 neutralizing antibody exacerbated CNV. The CCL2 expression in the laser-treated eyes of CXCR3-deficient mice was higher than in those of wild-type mice (P < 0.05), whereas VEGF, PEDF, and C3 showed no differences. These results suggested that CXCR3 expressed on CNV could have an angiostatic effect on it.

Leakage power reduction techniques of 45 nm static random access memory (SRAM) cells

As the technology scales down to 90 nm and below, static random access memory (SRAM) standby leakage power is becoming one of the most critical concerns for low power applications. In this article, we review three major leakage current components of SRAM cells and also discuss some of the leakage current reduction techniques including body biasing, source biasing, dynamic VDD, negative word line, and bit line floating schemes. All of them are achieved by controlling different terminal voltages of the SRAM cell in standby mode. On the other hand, performance loss occurs simultaneously with leakage saving. To validate the effectiveness of low power techniques, the leakage current, static noise margin, and read current of SRAM cells, based on the UMC 45 nm complementary metal–oxide–semiconductor (CMOS) process with leakage current reduction techniques has been simulated. The results indicate that by using the dynamicVDD and source biasing schemes, greater leakage suppressing capability, although with a higher performance loss, can be obtained. Therefore, the SRAM cell optimization scheme must consider the trade-off between power consumption and speed performance. Key words: Bit line floating, body biasing, Dynamic VDD, low power design, negative word line, source biasing, static random access memory (SRAM).

Pea and wheat starch possess different processing characteristics and affect physical quality and viscosity of extruded feed for Atlantic salmon

The aim of the study was to investigate the effect of starch source, retention time in the preconditioner and screw speed (RPM) on physical quality of extruded fish feeds. The experiment was arranged in a three by two by two factorial design using three carbohydrate sources [wheat starch (WS), pea starch (PS) or a combination (WS_PS)], two retention times in the preconditioner [long (120 s) or short (62 s)] and two RPM in the extruder [high (300) or low (220)]. Physical quality was assessed by hardness, diameter, expansion ratio, Holmen durability (HDI), DORIS value (DV), oil absorption capacity, oil leakage and pasting viscosity. The results showed that retention time in the preconditioner only affected HDI and oil leakage. Long retention time improved HDI but caused a greater leakage. Changing screw speed from 220 to 300 RPM gave a greater expansion ratio, improved HDI and oil absorption. PS resulted in higher pasting viscosity, HDI and DV, but a generally lower hardness than WS. To conclude, PS and WS have different processing characteristics, and the conditions need to be adjusted according to the starch source used when producing extruded fish feed.

Leakage Power Reduction Techniques of 55 nm SRAM Cells

As the technology scales down to 90 nm and below, static random access memory (SRAM) standby leak-age power is becoming one of the most critical concerns for low power applications. In this article, we re-view three major leakage current components of SRAM cells and also discuss some of the leakage current reduction techniques including body biasing, source biasing, dynamic VDD, negative wordline, and bitline floating schemes. All of them are achieved by controlling different terminal voltages of the SRAM cell in standby mode. On the other hand, performance loss occurs simultaneously with leakage saving. To validate the effectiveness of low power techniques, the leakage current, static noise margin, and read current of SRAM cells, based on the UMC 55 nm CMOS process with leakage current reduction techniques has been simulated. The results indicate that by using the dynamic VDD and source biasing schemes, greater leakage suppressing capability, although with a higher performance loss, can be obtained. Therefore, the SRAM cell optimization scheme must consider the trade-off between power consumption and speed performance.