Reference Counter Research Articles

Concurrent Immediate Reference Counting

Memory management for optimistic concurrency in unmanaged programming languages is challenging. Safe memory reclamation (SMR) algorithms help address this, but they are difficult to use correctly. Automatic reference counting provides a simpler interface, but it has been less efficient than SMR algorithms. Recently, there has been a push to apply the optimizations used in garbage collectors for managed languages to elide reference count updates from local references. Notably, Fast Reference Counter, OrcGC, and Concurrent Deferred Reference Counting use SMR algorithms to protect local references by deferring decrements or reclamation. While they show a significant performance improvement, their use of deferral may result in growing memory usage due to slow reclamation of linked structures, and suboptimal performance in update-heavy workloads. We present Concurrent Immediate Reference Counting (CIRC), a new combination of SMR algorithms with reference counting. CIRC employs deferral like other modern methods, but it avoids their problems with novel algorithms for (1) immediately reclaiming linked structures recursively by tracking the reachability of each object, and (2) applying decrements immediately and deferring only the reclamation. Our experiments show that CIRC’s memory usage does not grow over time and is only slightly higher than the underlying SMR. Moreover, CIRC further narrows the performance gap between the underlying SMR, positioning it as a promising solution to safe automatic memory management for highly concurrent data structures in unmanaged languages.

CredsCache: Making OverlayFS scalable for containerized services

OverlayFS, a Linux kernel driver for the Docker container, supports access control in Linux. User processes in the container must have appropriate privileges to access files in the backing file system. To that end, OverlayFS temporarily overrides credentials of a process with the mounter’s credentials whenever the process accesses a file, inode, or directory. However, we found that this mechanism incurs severe overhead owing to contention in updating a shared reference counter for the mounter’s credentials, which hinders OverlayFS scalability. In this paper, we propose a credential caching scheme, CredsCache, which greatly relieves contention by maintaining a per-process cached version of the mounter’s credentials. In CredsCache, each process performs credential overriding and reverting using its own cached version without updating the shared reference counter. We implemented CredsCache in OverlayFS and evaluated its performance using micro- and macro-benchmarks. Using solid-state drive (SSD) backend storage, the micro-benchmark results showed that CredsCache achieved up to 23.3× and 54.7× higher performance for data and metadata I/O, respectively, than vanilla OverlayFS. Moreover, the macro-benchmark and real-world benchmark results showed that CredsCache produced up to 5.6× and 2.9× better performance for respective database and web server benchmarks than vanilla OverlayFS.

Development of a Reference Device for the Calibration of Optical One-Shot Time-Interval Measurements

This paper presents the development of a device that creates two or more light pulses with a precision time delay in a range from microseconds to several seconds and for the purpose of the calibration of velocity of detonation (VOD) measurement instruments. The device was assembled, programmed, and tested for functionality. Measurements were conducted using a reference counter. First, a precision OCXO (oven-controlled crystal oscillator) was used as a clock source. For verification of programmed subroutines, a counter oscillator output port was used as a source of clock signal for the microcontroller. This enabled the cancellation of possible oscillator errors. The signal had to be converted from an AC sine signal to a signal with positive values only using a clamper circuit. By the proposed solution, a calculable standard of time delay between two light pulses was achieved. According to the obtained results, this device can be used to calibrate field measurement devices for VOD measurements in explosives or some other use where the measurement device records the time interval between multiple light pulses. This enables more confidence in measurement results, faster recognition of instrument drift and increases the quality of measurement.

Design of an amorphous ZnWSe2 alloy-based counter electrode for highly efficient dye-sensitized solar cells

Amorphous ZnWSe2 alloy-based counter electrodes grown by magnetron sputtering technique can indeed possess superior optoelectronic properties, resulting in a substantial efficiency of 8.27% and prolonged photostability.

Effect of Spherical Tungsten Carbide Load to the Corrosion Behaviour of Plasma Transfer Arc Hard Facing in Acidic and Alkaline Environment

Plasma transfer arc welding (PTAW) has been one of the popular methods for depositing thick hard facing. In this study, this method was used to lay the nickel hard-facing without tungsten carbide and with different compositions which are 35 wt%, 50 wt% and 60 wt% carbides. The hard facing was characterised using a scanning electron microscope with EDS and x-ray diffractometer (XRD). The corrosion behaviour was evaluated using three electrodes electrochemical test with saturated calmonel electrode (SCE) and platinum plate as the reference electrode and counter electrode respectively. The corrosion test shows that the hard facing had higher corrosion resistance in an alkaline environment compared to an acidic environment. The corrosion mechanism was by the dissolution of the nickel matrix, Ni3B dissolution is seen in an acidic environment while in alkaline electrolyte, the dendritic nickel dissolves preferentially.

Event-Driven ECG Sensor in Healthcare Devices for Data Transfer Optimization

The long-term monitoring of cardiovascular signs requires a wearable and connected electrocardiogram (ECG) healthcare device. It increases user’s comfort and diagnosis quality of chronic cardiac and/or high-risk patients. This paper covers the enormous data to be transmitted from the ECG device to the physician’s, namely the cardiologist’s, control unit. Existent ECG devices uniformly sample analog signals and convert them to digital samples which are compressed before data transmission. However, event-driven sampling simultaneously compresses and samples. Therefore, this paper quantitatively compares successive approximation register analog-to-digital converter (SAR ADC) with discrete wavelet transform (DWT) compression and level-crossing analog-to-digital converter (LC-ADC). Evaluation metrics are the percent root-mean-square difference ( {text{PRD}} ), bit compression ratio ( {text{BCR}} ) and data length in bits. When a 12-bit reconstruction is operated on the outputs of an 8-bit LC-ADC with 12-bit and 10-kHz reference counter, the {text{BCR}} is equal to 80% for 75% of test ECG signals. That is better than the 71.87% {text{BCR}} of the 12-bit 1-kHz SAR ADC with DWT compression. The modeled LC-ADC guarantees a signal quality in terms of {text{PRD}} comparable to the {text{PRD}} of the SAR ADC with DWT compression. The data length in bits of the LC-ADC is lower than the data length in bits of the SAR ADC with more than 14-bit resolution with DWT compression for 82% of the test ECG signals. However, for lower resolutions, to obtain lower power consumption for radiofrequency transmission, a better alternative remains the SAR ADC with DWT compression.

Toward Linux kernel memory safety

SummaryThe security of billions of devices worldwide depends on the security and robustness of the mainline Linux kernel. However, the increasing number of kernel‐specific vulnerabilities, especially memory safety vulnerabilities, shows that the kernel is a popular and practically exploitable target. Two major causes of memory safety vulnerabilities are reference counter overflows (temporal memory errors) and lack of pointer bounds checking (spatial memory errors). To succeed in practice, security mechanisms for critical systems like the Linux kernel must also consider performance and deployability as critical design objectives. We present and systematically analyze two such mechanisms for improving memory safety in the Linux kernel, ie, (1) an overflow‐resistant reference counter data structure designed to securely accommodate typical reference counter usage in kernel source code and (2) runtime pointer bounds checking using Intel memory protection extension in the kernel. We have implemented both mechanisms and we analyze their security, performance, and deployability. We also reflect on our experience of engaging with Linux kernel developers and successfully integrating the new reference counter data structure into the mainline Linux kernel.

FRC: a high-performance concurrent parallel deferred reference counter for C++

We present FRC, a high-performance concurrent parallel reference counter for unmanaged languages. It is well known that high-performance garbage collectors help developers write memory-safe, highly concurrent systems and data structures. While C++, C, and other unmanaged languages are used in high-performance applications, adding concurrent memory management to these languages has proven to be difficult. Unmanaged languages like C++ use pointers instead of references, and have uncooperative mutators which do not pause easily at a safe point. Thus, scanning mutator stack root references is challenging. FRC only defers decrements and does not require mutator threads to pause during collection. By deferring only decrements, FRC avoids much of the synchronization overhead of a fully-deferred implementation. Root references are scanned without interrupting the mutator by publishing these references to a thread-local array. FRC's performance can exceed that of the C++ standard library's shared pointer by orders of magnitude. FRC's thread-safety guarantees and low synchronization overhead enable significant throughput gains for concurrently-readable shared data structures. We describe the components of FRC, including our static tree router data structure: a novel barrier which improves the scalability of parallel collection workers. FRC's performance is evaluated on several concurrent data structures. We release FRC and our tests as open-source code and expect FRC will be useful for many concurrent C++ software systems.

An electrocatalytic active lyocell fabric cathode based on cationically functionalized and charcoal decorated graphite composite for quasi-solid state dye sensitized solar cell

Abstract The state of the art of conductive functional textile woven fabrics have given rise to a demand for textile integrated electrodes. Herein, we report a highly conductive and flexible woven fabric electrode using highly absorbent lyocell fabric as the substrate and cationically functionalized and activated charcoal decorated graphite composite (AC-GC) as the coating film. This (AC-GC) coated lyocell fabric is used as a cathode for quasi-solid state dye sensitized solar cell (Q-DSSCs). Our suggested fabric based cathode shows sufficiently high conductivity and electrocatalytic activity (ECA) compared to platinum (Pt) based reference counter electrode (CE). This efficient CE demonstrates extremely low charge transfer resistance (RCT) of 1.56 Ω cm2 with polyethylene oxide based quasi-solid electrolyte. The cationic charged enriched charcoal decorated graphite planner structure provide more availability of active sites for the reduction of negatively charged tri-iodide ( I 3 - ) ions present in polymeric gel electrolyte. The formation of porous charcoal voids and conductive graphite channels entrap large amounts of gel electrolyte and provide fast diffusion of iodide/tri-iodide ( I - / I 3 - ) ions. Our organic system of AC-GC coated lyocell fabric based DSSCs assembly demonstrated 7.09% power conversion efficiency (PCE) when fabricated with quasi-solid electrolyte. This AC-GC coated fabric CE is also highly stable in water and electrolyte solution. The adequate electrocatalytic activity and cyclic stability demonstrate that this AC-GC coated fabric can be used to replace expensive Pt CE and can be used in flexible solar cells in future.

Performance study of various Condensation Particle Counters (CPCs): development of a methodology based on steady-state airborne DEHS particles and application to a series of handheld and stationary CPCs

Strategies for measuring occupational exposure to aerosols composed of nanoparticles and/or ultrafine particles highlight the use of techniques for determining airborne-particle number concentration as well as number size distribution. The objective of the present work was to set up a system for conducting laboratory verification campaigns of condensation particle counters (CPCs). Providing intercomparison data as well as calibrating and checking CPCs are among the key elements in ensuring reliable laboratory or field measurement campaigns. For this purpose, the reproducible aerosol source “Calibration Tool”, initially developed by the Fraunhofer ITEM, was acquired by the Laboratory of Aerosol Metrology at INRS. As a first part of this study, a detailed characterization of the Calibration Tool developed at the laboratory is the subject of the parametric study presented here. The complete installation is named the “DCC” for “Device for Counter Check”. Used in combination with a reference counter, the DCC can now be used for routine laboratory measurements. Unlike that used for primary calibration of a CPC, the proposed protocol allows a wide range of number concentrations and particle sizes to be investigated and reproduced. The second part of this work involves comparison of the number concentrations measured by several models of CPC in parallel at the exit of a flow splitter, with respect to a reference.

나노컴포지트 카본 잉크가 전착된 일회용 도파민 바이오센서

A new nano-composite carbon ink for the development of disposable dopamine (DA) biosensors based on screen-printed carbon electrodes (SPCEs) is introduced. The method developed uses SPCEs coupled with a tyrosinase modified nano-composite carbon ink. The ink was prepared by an “in-house” procedure with reduced graphene oxide (rGO), Pt nanoparticles (PtNP), and carbon materials such as carbon black and graphite. The rGO-PtNP carbon composite ink was used to print the working electrodes of the SPCEs and the reference counter electrodes were printed by using a commercial Ag/AgCl ink. After the construction of nano-composite SPCEs, tyrosinase was immobilized onto the working electrodes by using a biocompatible matrix, chitosan. The composite of nano-materials was characterized by X-ray photoelectron spectroscopy (XPS) and the performance characteristics of the sensors were evaluated by using voltammetric and amperometric techniques. The cyclic voltammetry results indicated that the sensors prepared with the rGO-PtNP-carbon composite ink revealed a significant improvement in electro-catalytic activity to DA compared with the results obtained from bare or only PtNP embedded carbon inks. Optimum experimental parameters such as pH and operating potential were evaluated and calibration curves for dopamine were constructed with the results obtained from a series of amperometric detections at -0.1 V vs. Ag/AgCl. The limit of detection was found to be 14 nM in a linear range of 10 nM to 100 μM of DA, and the sensor’s sensitivity was calculated to be 0.4 μAμM −1 cm −2 .

All-Solid-State Lithium Secondary Battery Using Plastic Crystal As Solid Electrolyte

Introduction All-solid-state lithium ion batteries (ASS-LIBs), which consist of nonflammable solid electrolyte, are expected as high capacity and safety secondary batteries for vehicle and industrial use. Bulk-type ASS-LIBs, whose positive and negative electrodes are composed of an active material, a conductive agent, a binder and a solid electrolyte, are more desirable than film type electrode, in terms of capacity and energy density. A main issue of the bulk-type ASS-LIBs is reduction of internal resistance of the electrodes, which originated from a poor contact between the electrolyte and the active materials to form the micro void. Plastic crystalline fast ion conductors have been studied as the solid-state electrolyte for ASS-LIBs [1, 2]. As these materials readily deform above relatively low melting point, for example 1-ethyl-1-methyl pyrolidinium bis(trifluoromethylsulfonyl imide (12PyrTFSI) melt at 90 °C, it will form a favorable active material-electrolyte solid-solid interface. In this study, to reduce the internal resistance of the electrode, lithium ion conductive plastic crystals which show thermoplasticity was used as solid electrolyte. Experimental In this research, a mixture of 12PyrTFSI and lihium sulfonyl imide (LiTFSI) was used as lithium conductive plastic crystal. We developed a negative electrodes consisting of lithium titanium oxide (LTO), acetylene black, polyvinylidene fluoride, the mixture of 12PyrTFSI, LiTFSI. The negative electrode was obtained by coating the dispersion slurry containing the above mentioned materials and N-methylpyrrolidone (NMP), and thereby drying NMP solvent. Drying temperature was selected more than 71 °C that is a melting point of the mixture of 12PyrTFSI and LiTFSI [3]. The negative electrodes were structurally characterized by SEM-EDX. The anode half cell was prepared by assembling the anode on a polyethylene oxide (PEO) polymer sheet and Li foil as reference counter electrode to measure the charge and discharge property of the negative electrodes. At 50 °C, the charge and discharge were operated in the galvanostatic mode at 5.57 μA¥cm-2 (0.02C). The internal resistance of the negative electrode after charge was obtained using an impedance analyzer over a frequency range of 0.1 to 106 Hz and amplitude of 10 mV at 50 °C. The cells were cycled between 1 to 1.35 V vs. Li/Li+. Fig.1 illustrates the charge and discharge curves of the LTO negative electrode with a plastic crystal. The discharge capacity at the first cycle was 82 mA¥g-1 at 0.02 C, which is only 47 % of theoretical capacity. The cross sectional SEM images showed that the plastic crystal was not uniformly distributed in the electrode. Conceivably, the non-uniform distribution resulted in the formation of heterogeneous lithium ion conduction path over the negative electrode, deteriorating the discharge capacity. Fig. 2 shows Nyquist plots of the negative cell after first charging. The interfacial resistance between lithium metal and PEO polymer sheet and internal resistance of the negative electrode forms an arc. It shows the small resistance of the negative cell 55 Ωcm2. Evidently, partial ion conduction path comprising of 12PyrTFSI and LiTFSI contributed to the low internal resistance of the negative cell. It was concluded that the formation of the homogeneous ion conduction path was needed to increase the capacity of the negative electrode.

Studying the timing characteristics of counters for the trigger hodoscope of charged particles for the NA62 experiment

The time resolution of the prototype counters for a new charged particle hodoscope for the NA62 experiment has been measured. The prototype scintillation counters with dimensions of 90 × 90, 100 × 100, 150 × 150, 180 × 100, and 270 × 100 mm are investigated. Several variants of direct light collection from a scintillator brink and a corner are considered, as well as light collection using wavelength-shifting (WLS) fibers. Silicon photodiodes from the Centre of Perspective Technologies and Apparatuses (CPTA) and SensL, as well as a compact R7400U photomultiplier tube were used as photodetectors. An R7899-20 photomultiplier tube with a high quantum efficiency in the green spectral region is used as a reference counter. The measurements have been taken with cosmic muons and the beam halo of beamline 21 in the zone of the OKA experiment. The time resolution of a 100 × 100 mm cell, averaged over the area, is 590 ± 10 ps in the case of the WLS-fiber readout and 260 ± 25 ps in the case of direct light collection from the scintillator brink.

Development of a Fast Timing Counter with a Monolithic MPPC Array

We developed a timing counter with a monolithic array of multi-pixel photon counters (MPPCs) coupled to a <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$10 \times 12.6 \times 24~\hbox{mm}^3$</tex></formula> plastic scintillator. A signal of the MPPC was processed and its fast components were amplified by a developed readout circuit to improve the timing. The performances of the counter were evaluated by electrons with energies of 855 MeV. A set of the MPPC based scintillation counter and a PMT based reference counter achieved the TOF resolution less than 80 ps ( <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\sigma $</tex></formula> ). The gain was almost constant up to the count rate of 170 kHz.

Bias Modulated Scanning Ion Conductance Microscopy

Nanopipets are versatile tools for nanoscience, particularly when used in scanning ion conductance microscopy (SICM) to determine, in a noncontact manner, the topography of a sample. We present a new method, applying an oscillating bias between a quasi-reference counter electrode (QRCE) in the SICM nanopipet probe and a second QRCE in the bulk solution, to generate a feedback signal to control the distance between the end of a nanopipet and a surface. Both the amplitude and phase of the oscillating ion current, induced by the oscillating bias and extracted using a phase-sensitive detector, are shown to be sensitive to the probe-surface distance and are used to provide stable feedback signals. The phase signal is particularly sensitive at high frequencies of the oscillating bias (up to 30 kHz herein). This development eliminates the need to physically oscillate the probe to generate an oscillating ion current feedback signal, as needed for conventional SICM modes. Moreover, bias modulation allows a feedback signal to be generated without any net ion current flow, ensuring that any polarization of the quasi reference counter electrodes, electro-osmotic effects, and perturbations of the supporting electrolyte composition are minimized. Both feedback signals, magnitude and phase, are analyzed through approach curve measurements to different surfaces at a range of distinct frequencies and via impedance measurements at different distances from a surface. The bias modulated response is readily understood via a simple equivalent circuit model. Bias modulated (BM)-SICM is compared to conventional SICM imaging through measurements of substrates with distinct topographical features and yields equivalent results. Finally, BM-SICM with both amplitude and phase feedback is used for topographical imaging of subtle etch features in a calcite crystal surface. The 2 modes yield similar results, but phase-detection opens up the prospect of faster imaging.

Fretting-Corrosion of 316L Steel Metallic Biomaterial Methodological Aspects

Methodological aspects of fretting and fretting-corrosion research of metallic biomaterials are presented in this article. At the Faculty of Mechanical Engineering Technical University of Bialystok tribometer device was constructed to test the fretting phenomenon with flat-on-flat contact configuration [. Based on the results of published research the fretting regimes were established. Values of the amplitude of reversible movement were 80-120 µm, the frequency was 1 Hz [2] and the value of the pressure was 20 MPa. Fretting-corrosion tests in simulated biological fluids should be performed in the three-electrode system in presence of the reference electrode and counter electrode along with the working electrode to the potentiostat. It is important to leave the system loaded and immersed for about 30 minutes prior to testing the potential of the system. During that time system potentials are stabilized. After that, acquiring data for fretting corrosion should be started with measurement potential/time changes [. A better understanding of the fretting processes will largely eliminate its effects at the construction design stage.

Evaluation of the analytical performances of a portable, 18-parameter hemometric system using capillary blood samples for blood donor enrolment

Blood donor enrolment process is frequently based on the sole capillary haemoglobin (Hb) evaluation while platelet donors by apheresis also requires platelet (Plt) count. The 'sole Hb' approach prevents a complete donor evaluation and does not allow Plt donor enrolment. To extend blood counts before donations, we evaluated the performances of a multiparametric counter using capillary blood. The ABX Micros 60 (Micros 60) blood analyzer was employed on capillary blood and compared with venous counts by a reference counter (Coulter AcT 5diff) in a first series of 416 donors and in a second series of 136, after a 3-month period of routine use of this study counter. An average of 50 microl of capillary blood was collected whose 10 microl had been aspirated by Micros 60. High correlations were found between capillary counts using Micros 60 and venous counts using the reference counter. Mean Plt counts differed of 37 x 10(9)/l less for capillary approach in the first series of comparisons, but decreased to 10 x 10(9)/l less in the second series due to a greater expertise of operators in capillary sampling. All other parameters were accurate and never reached clinical relevance albeit they showed statistically significant differences. Data on Micros 60 demonstrated that capillary predonation counts may represent a feasible and effective approach to realize an accurate enrolment process of blood and Plt donors.

Communication Breakdown: Librarian and Student Approaches to Virtual Reference Differ

A review of:&#x0D; &#x0D; Walter, Virginia A. and Cindy Mediavilla. "Teens Are from Neptune, Librarians Are from Pluto: An Analysis of Online Reference Transactions.” Library Trends 54.2 (2005): 209-227.&#x0D; &#x0D; Objective – To evaluate the effectiveness of an online reference and referral service for students (primarily those in middle school and high school) seeking homework help.&#x0D; &#x0D; Design – Analysis of 114 transcripts of reference transactions. &#x0D; &#x0D; Setting – A centralized homework reference and tutor referral service provided on behalf of the California State Library by the Metropolitan Cooperative Library System. &#x0D; &#x0D; Subjects – Virtual reference librarians at a large urban library system and middle and high school students in California.&#x0D; &#x0D; Methods – One hundred fourteen virtual reference transactions recorded between October 12 and November 8, 2003 were evaluated against the Reference and User Services Association’s (RUSA) “Guidelines for Behavioral Performance of Reference and Information Service Providers.” Secondly, the transcripts were subjected to discourse analysis.&#x0D; &#x0D; Main results – Performance of virtual reference librarians vis-à-vis RUSA guidelines&#x0D; In the majority of cases, there was some evidence that librarians communicated clearly (110 out of 114 transactions). In 78 cases, it appeared that a librarian was available quickly, and in 92 of the transactions a friendly greeting was given. What was striking, however, was that in a clear majority of cases, some of the classic reference interview strategies were not employed. In 100 or more cases each, the following strategies were not observed: repeating or paraphrasing the question; helping to interpret the question; verifying mutual understanding; asking if the question has been answered; asking if the student needs more information. Furthermore, in 75 cases librarians did not probe for further information to clarify the question, while in 87 cases they did not check that information had been clearly understood. &#x0D; &#x0D; Possibly related to these findings, the researchers felt that the transcripts revealed “a conviction that homework questions are not the proper content for reference transactions” (222). In addition, librarians were found to be frequently too quick to refer students to a tutor, when a query might have been better answered as a reference question.&#x0D; &#x0D; Findings of discourse analysis&#x0D; In general, the virtual reference librarians used impersonal, formal language to “reinforce the professional’s superior position vis-à-vis the help-seeker” (217). There were repeated attempts by the students to interject a lighter or warmer tone (using humour, emoticons, informal language, introducing a personal note, etc.). These attempts were rarely reciprocated, with librarians continuing to use impersonal language, including stock messages such as:&#x0D; “we are experiencing a very busy time right now,” (217); or,&#x0D; “I am going to send you a page which will give you some help with your homework.&#x0D; After we disconnect this session, click on this link and follow the instructions to be connected with a tutor. Please do not click on any links on this page until after we have disconnected” (217).&#x0D; &#x0D; In several cases librarians were preoccupied with defining their roles—for example, specifying that they could give reference help but not advice. In all, the distancing mechanisms used by librarians, combined with occasional inaccurate referrals and technical problems with the software, were seen to create an enormous potential for frustration on the part of the student.&#x0D; &#x0D; Conclusions – The most important implication of the study was that librarians and students were worlds (or planets) apart in their approach to the reference interaction. While “teens attempted to create meaning by recreating the chat discourse environment in which they were most at home”, librarians “tried to create meaning in a parallel discourse environment that duplicated as much as possible the standard impersonal protocols of a face-to-face reference counter” (223). One suggested way to alleviate the disconnect between librarians and students was to involve students in the planning of the services. For now, however, the authors conclude that “teens are from Neptune, librarians are from Pluto. Better services would result if they could meet somewhere closer together” (224).&#x0D;

AFM and electrochemical study of the effect of dodecylamine on carbon steel corrosion

The adsorption-type inhibitors play an important role in preventing corrosion of metals in acidic solutions, so the study of the relations between the adsorption and corrosion inhibition is of great importance. Dodecylamine is considered as adsorption-type inhibitor for carbon steel in acidic solutions [1]. Polarization curve measurement is commonly employed in inhibitor research. For example, the modes of inhibition effect of interface inhibitors can be classified by polarization curve [2], corrosion current densities or inhibition efficiencies are often estimated by extrapolation of polarization curves to corrosion potentials. In some cases, equations of adsorption isotherms of interface inhibitors are obtained from plots of the inhibition efficiencies vs concentrations of the inhibitors studied [3–6]. Atomic force microscopy (AFM) is receiving considerable attention in the field of surface science and engineering, it has also been successfully applied to the investigation of corrosion processes and proofed to be an excellent tool [7, 8], however since the roughness of the surface is much higher compared with adsorption film, especially when the film is monolayer, it is very difficult to evaluate the adsorption behavior of inhibitors through imaging surface topography, but the conductivity of the surface will be changed after the adsorption of inhibitor, and the force curves will also exhibit different characters after the adsorption of inhibitor. The application of AFM current image and force curves will be new ways to investigate the adsorption behavior of inhibitor. The aim of this study is to present new methods to evaluate the inhibitor adsorption behavior. Firstly, the polarization curves were applied to study the adsorption behavior of dodecylamine on carbon steel, then the current image and force curves of carbon steel surface after immersion in test solution containing inhibitor were measured. All the tests were performed on carbon steel of the following composition (wt.%): C, 0.24; Mn, 1.19; P, 0.013; S, 0.004; Cr, 0.036; Mo, 0.021; Ni, 0.028; Fe, Remainder. The base solution was HCl solution, and the inhibitor is dodecylamine. All the solutions were prepared from analytical grade reagents and distilled water. The electrochemical measurements were conducted through a three-electrode cell connected to a Zahner IM6e electrochemical workstation. A platinum electrode and a saturated calomel electrode (SCE) were used as reference electrode and counter electrode respectively. Polarization curves were obtained by sweeping the potential from a value of )200 to 200 mV vs. Ecorr with a potential scan rate of 0.5 mV s. The working electrode for electrochemical tests was embedded in PTFE ring leaving an area of 1 cm exposed to solution. Before tests, the samples were wet ground through 1200 grit SiC paper, rinsed with distilled water and ethanol, dried at room temperature. The topography of the sample surface was measured with a commercial AFM system (SPI3800, Seiko Instruments Inc.) operated in contact mode, and the current image was simultaneously measured by applying a bias voltage of 0.5 V between the sample and the Au-coated conductive tip. Specimens for AFM measurement were wet ground through 1200 grit SiC paper, and then polished to 0.5 lm with diamond paste using a polishing cloth. After being rinsed with distilled water and treated with supersonic cleaning in ethyl alcohol, the samples were stored in air. Z. Y. Chen AE X. P. Guo (&) AE Q. Zhang AE J. E. Qu Department of Chemistry, Huazhong University of Science and Technology, Wuhan 430074, P R China e-mail: guoxp@mail.hust.edu.cn J Mater Sci (2006) 41:5033–5035 DOI 10.1007/s10853-006-0104-x

An energy efficient garbage collector for java embedded devices

This paper presents a detailed design and implementation of a power-efficient garbage collector for Java embedded systems. The proposed scheme is a hybrid between the standard mark-sweep-compact collector available in Sun's KVM and a limited-field reference counter. There are three benefits resulting from the proposed scheme. (a) the proposed scheme reclaims memory more efficiently and this results in less mark-sweep garbage collection invocations, (b) reduction in garbage collection invocations improves cache locality and reduces the number of main memory accesses, and (c) reduction in memory access ultimately results in lower energy consumption, since a memory access can consume a large amount of energy when compared with an instruction execution. The proposed scheme has been implemented into Sun's KVM, and has been shown to reduce the number of mark-sweep garbage collection invocations by up to 100% in some cases, and the number of level-1 cache misses by as much as 87% when compared to the default garbage collector. We also find that in some applications, the proposed scheme can reduce the power consumption by as much as 27% when compared to the default Sun's KVM.