A fiber-optic absorption cell for remote determination of copper in industrial electroplating baths

A device for remote optical sensing is developed and evaluated for monitoring the concentration of copper(II) ions in an industrial plating bath. The sensor consists of an absorption cell which resides in the plating bath, and utilizes fiber optics to direct light into and out of the cell. The sensor is capable of being located in harsh environments for extended periods of time (on the order of weeks to years) and thus is ideal for long-term monitoring applications. The light source and detection electronics can be maintained in a controlled environment and can be multiplexed to several sensors of similar design, if desired. The sensor constructed operates by measuring the copper(II) absorbance with a near-infrared light-emitting diode (820 nm) as the light source. The device is capable of measuring copper(II) ion concentrations from 50 mM to 500 mM with relative standard deviations less than 1%. The construction and operation of the sensor are described and the effects of various interferences found in plating baths are evaluated, including those from temperature variations and variations in the concentrations of concomitant species in the plating bath. Also, drift compensation and noise sources are considered, with an evaluation of the long-term stability of the sensor and the feasibility of its use in an industrial environment.     

Determination of Hydrogen Sulfide by Wavelength-modulated Diode Laser Absorption Spectroscopy

Rapid, accurate, and sensitive determination of hydrogen sulfide was provided by tunable distributed feedback diode laser absorption spectroscopy. The laser wavelength scanning range covered the strongest absorption band of hydrogen sulfide. The absorption line at 1578?nm was used for analytical measurements. A homemade digital lock-in amplifier was used to demodulate the first and the second harmonic signals. Normalization of the second harmonic by the first harmonic signal provided calibration-free measurements so that interferences from light path, circuitry, and source intensity were minimized. A mass flow controller was used to introduce 0–100?ppm hydrogen sulfide for validating the analytical performance. The results demonstrated the linearity of the normalized harmonic signals with concentration with a correlation coefficient of 0.9995. The response time was approximately 3?s. The detection limit by Allan variance was 45 ppb with an integration time of 35?s. The sensitive hydrogen sulfide sensor is suitable for environmental monitoring with real-time detection.     

Ionic and atomic absorption in stable spark discharges

Transient ionic and atomic emission-absorption measurements on a train of positionally-stable copper spark discharges are described. The measurements are made as a function of discharge current duration at constant amplitude and rise time. Spatial observation zones are isolated in the spark gap with a set of masks and a relay lens to estimate the movement of electrode vapor. Absorption measurements required custom circuitry for a pulsed hollow-cathode backlight and synchronously gated dual-channel boxcar integrator. Results indicated that electrode vapor moves primarily along the interelectrode axis in response to current duration, with substantial ionization remaining in the post-discharge period. Neutral atoms remain in the gap for long times after current cessation.     

A fully automated mass spectrometer for the analysis of organic solids

Automation of a mass spectrometer—computer system makes it possible to process up to 30 samples without attention after sample loading. An automatic sample changer introduces the samples successively into the ion source by means of a direct inlet probe. A process control unit determines the operation sequence. Computer programs are available for the hardware support, system supervision and evaluation of the spectrometer signals. The most essential precondition for automation — automatic evaporation of the sample material by electronic control of the total ion current — is confirmed to be satisfactory. The system operates routinely overnight in an industrial laboratory, so that day work can be devoted to difficult analytical problems. The cost of routine analyses is halved.     

具有串/并联复合离子输运特性的仿生纳米通道的构筑与整流性能

人工构筑了基于分枝氧化铝纳米通道的串/并联复合的纳流体二极管体系, 其具有可调的离子整流性能. 在这种两级分枝结构的1-2-2, 1-2-3, 1-3-2和1-3-3型氧化铝纳米通道中, 若将每一个分枝节点等效为一个二极管, 那么其一级分枝节点相当于串联的1个二极管, 二级分枝节点相当于并联的多个二极管. 因此1-2-2和1-2-3型纳米通道的电路图可等效为并联的2个二极管与第3个二极管相串联, 1-3-2和1-3-3型纳米通道的电路图可等效为并联的3个二极管与第4个二极管相串联. 但由于1-2-2和1-2-3型以及1-3-2和1-3-3型的二级分枝的结构和数目不同, 可将这4种纳米通道等效为不同的串/并联复合特性的纳流体二极管体系, 并且表现出依次增大的离子整流. 即分枝氧化铝纳米通道内部一级分枝和二级分枝的结构或数目共同调控的表面电荷非对称性可以改变其离子整流性能. 进一步地, 具有代表性的1-2-2型分枝纳米通道的整流率随分枝通道长度的增加而增加, 这表明分枝部分对整个串/并联复合纳流体二极管的整流特性起到决定性的作用. 相比于以前的单个离子二极管体系, 这种具有串/并联复合特性的多级分枝氧化铝纳米通道将为构筑更复杂的仿生纳流体二极管的研究提供有价值的借鉴.     

Enabling luminescence decay time-based sensing using integrated organic photodiodes

The use of organic photodiodes (OPDs) for measuring phosphorescent lifetimes of optochemical oxygen sensors is described. Phosphorescent indicators with lifetimes ranging from ～5 to 60 μs have been studied using light-emitting diodes as the excitation source and organic photodiodes integrated into the sensor substrate for detection. A measurement system using an adjusted electronic circuitry to detect photocurrents in the nanoampere range is presented. The response behaviour of the organic photodiodes has been characterized, and it was found that a forward (positive) bias had to be applied in order to decrease the response time of the OPDs to a range suitable for phosphorescence decay time measurements. A modulation cutoff frequency of ～100 kHz has been determined, corresponding to a response time of the organic photodiodes of 1.6 μs. Two sensor dyes have been characterized regarding their lifetimes upon exposure to 0–20 % oxygen, and it was shown that results comparable to literature data and inorganic photodetectors can be achieved.     

Development of diode junction nuclear battery using 63Ni

The diode junction nuclear battery is a long-lived, high-energy-density, but low electrical current power source with many specialized applications. In this type of battery, nuclear radiation is directly converted to electric power. A model is described and used to design the device configuration. Details of fabrication and testing of a planar geometry battery with ⁶³Ni radiation source are described. The electron beam induced current (EBIC) measurement technique and CASINO Monte Carlo simulation code were employed to analyze the device performance. Finally, an improved design with 3-dimensional surface microstructures that will provide improved performance is presented.     

Rapid dissolution of metal in aqueous media using a modified commercial spark source unit

In this preliminary study the feasibility of a modified spark source was investigated as a method of rapidly dissolving solid conductive samples in aqueous media prior to analysis by atomic spectroscopy. The spark source, originally designed for spark emission spectroscopy in air, was modified by the installation of a spark ablation vessel. This spark ablation vessel was designed for spark ablating samples in aqueous solution, such as deionised water. Samples such as mild steel and brass were ablated in 5–10 ml of deionised water for 2–30 s producing a colloidal suspension. The suspension was readily dissolved by adding 100 μl of concentrated HCl or HNO₃. In this paper the spark ablation vessel is described as well as some of the properties of spark ablation in aqueous solutions. Spark ablation rates on mild steel were measured with respect to spark ablation parameters such as applied current (power), polarity and spark time. Using mild steel as a test sample, spark ablation rates varied from 40 μg s⁻¹, with 2.5 A of applied current, to 70 μg s⁻¹ with 10 A of applied current to the electrodes. The feasibility of using this technique for analysing trace levels (μg g⁻¹) of elements in solid samples was also demonstrated for elements such as Ni in brass with inductively coupled plasma mass spectrometry (ICP-MS). Quantification of selected elements (Cr, Ni, Mn and Cu) in a certified alloy (SRM 663) and a non-certified stainless steel showed good agreement between the measured values using spark ablation and the accepted values.     

A simple and compact blue diode laser powered excitation source for fluorescence detection in capillary electrochromatographic microchip separation

A simple and compact fluorescence excitation source was prepared using a 405 nm blue laser diode module and characterized in capillary electrochromatographic or capillary electrophoretic microchip separation. An inexpensive blue laser diode module with a tiny focusing lens was simply mounted at the center of an aluminum block on a miniature linear motion guide for heat dissipation and position control. A slit unit has a series of fifteen laser-machined slits with 1 mm space along the direction of the separation channel of the microchip above this unit. The laser beam was focused through a slit with 50 μm width to the separation channel at the position of a desired length. Although the excitation source unit was connected to a simple current controlled power supply, it was stable with 0.1% drift per hour and 1.3% (1σ) fluctuation in intensity. This simple excitation source can be prepared easily with inexpensive minimum optical components and mounted with a microchip on the stage of an ordinary fluorescence microscope for daily separation studies using a CE or CEC microchip. The applicability of the excitation source was evaluated with FITC-amino acid derivative mixtures using a polymer based CEC microchip packed fully with submicron silica beads in its microchannel.     

Construction of a microwave Fourier Transform Spectrometer

The construction of an X-Band Microwave Fourier Transform Spectrometer suited for high resolution studies is described.Special features are the phase locked klystron microwave power source which is pulse modulated by a PIN diode switch, a 20 meter low loss waveguide sample cell and the use of commercially available NMR signal processing components.Performance is demonstrated with OCS and CSFCl.     

Development of sulfonated poly (ether ether ketone) electrolyte membrane for applications in hydrogen sensor

The future economy is projected as hydrogen economy and fuel cells are set to become the energy source either replacing or augmenting the present oil based technology. A sulfonated poly ether ether ketone (SPEEK) membrane as the electrolyte for hydrogen sensor that operates at room temperature was developed in our lab. The electrolyte used was SPEEK, which is a proton conducting solid polymer membrane. The membranes were characterized using various available techniques like TGA, XRD, SEM, etc. The durability was studied using the Fenton’s reagent. The proton conducting ability was analyzed using impedance spectroscopy. The catalysts considered were platinum for the cathode and three different catalysts (Pt, Pt/Pd and Pd) for the anode. The MEAs were evaluated for their performance in hydrogen sensor and the one with platinum catalyst at the anode gave the best response among the three indicating its suitability for the SPEEK membrane for hydrogen sensor.     

Facile and efficient synthesis of star-shaped oligomers from a triazine core

A facile and efficient synthetic approach to tripodal star-shaped oligomers is described. Several generations of hydroxyl-terminated tripodal star-shaped oligomers were prepared in high yield from 1,3,5-triacryloylhexahydro-1,3,5-triazine (TAT) as a core by alternating amine-catalyzed thiol-ene and acrylate esterification reactions. The compounds were fully characterized by 1D and 2D NMR spectroscopy, ESI-MS, and elemental analysis. The combination of thioether groups and hydrogen bonding moieties suggests that these products can be used as metal chelating ligands.     

AN INSTRUMENT FOR SIMULTANEOUS ACQUISITION OF FLUORESCENCE SPECTRA AND FLUORESCENCE LIFETIMES FROM SINGLE CELLS

Abstract— An instrument is described that has the capability of acquiring both the spectrum and lifetime(s) of fluorescent species dispersed in biological cells. It operates at the single cell (or organelle) level and the spectral and temporal data collection can be performed simultaneously. A synchronously pumped, mode-locked dye laser provides the excitation light, time-correlated single-photon counting is used for lifetime measurements, and a diode array spectrograph is used for spectral work. Spatial resolution of sub-micrometer is obtained using a fluorescence microscope. The temporal resolution is better than 300 ps and wavelength resolution is less than 1 nm per channel. The instrument has been used for observing the spectral and temporal characteristics of hematoporphyrin in mouse myeloma cells.     

Integrated hydrogen leak detector with a tunnel mis structure

A simpler integrated hydrogen leak detector has been fabricated, which consists of a Pd-Si tunnel MIS diode for the hydrogen sensor, a diffused resistor layer for the inside heater and a p-n junction diode for temperature control. Measurements were carried out on the response characteristics to hydrogen at different device temperatures and hydrogen concentrations. The results show that the newly fabricated detector can be used as a practical detector for small leakage of hydrogen at a device temperature between 100 and 120 °C. It is also demonstrated that the tunnel MIS diode with a hole-structure Pd layer drastically improves the hydrogen sensitivity.     

Biofuel Cell Operating in Vivo in Rat

Biocatalytic electrodes made of buckypaper were modified with PQQ‐dependent glucose dehydrogenase on the anode and with laccase on the cathode. The enzyme modified electrodes were assembled in a biofuel cell which was first characterized in human serum solution and then the electrodes were placed onto exposed rat cremaster tissue. Glucose and oxygen dissolved in blood were used as the fuel and oxidizer, respectively, for the implanted biofuel cell operation. The steady‐state open circuitry voltage of 140±30 mV and short circuitry current of 10±3 µA (current density ca. 5 µA cm^?2 based on the geometrical electrode area of 2 cm²) were achieved in the in vivo operating biofuel cell. Future applications of implanted biofuel cells for powering of biomedical and sensor devices are discussed.     

发光二极管诱导荧光用于毛细管电泳检测

利用发光二极管作为激发光源，组装了用于毛细管电泳的荧光检测器。光纤用于传输荧光信号；光纤端面修饰成球形使耦合效率比平面端光纤提高了50．8％；光阑、光纤及毛细管检测池之间的光学校准简单、便捷。荧光素染料用于评价该体系性能，得到了fmol的质量检出限。     

Mild aerobic oxidative palladium (II) catalyzed C-H bond functionalization: regioselective and switchable C-H alkenylation and annulation of pyrroles

A palladium catalyzed C-H bond functionalization system that operates under ambient and aerobic conditions can be used to alkenylate pyrroles with control of regioselectivty. A steric and electronic control strategy can be used to influence positional control in the C-H bond functionalization process that results in either the C2 or C3 alkenylated products. Air, molecular oxygen, or tBuOOBz can be used as reoxidant in this mild process, and the reaction works on a range of substrates. Finally a catalytic aerobic annulation strategy is described that can be controlled to produce cyclization at either the C2 or C3 positions, thus forming diverse pyrrole products.     

On electrical sparks and their use for excitation of spectra

The spark discharges of the Feussner spark source were studied with a cathode ray oscillograph and a rotating mirror. The spark is a high frequency a.c. arc with a practically current independent, low burning voltage of about 50 V. The current curve is nearly sinusoidal. With a pure spark damping the amplitude decays linearly. In this case the number of high frequency oscillations is independent of the electrical parameters in the spark circuit. Because the burn voltage of the spark is dictated by the intenal mechanism of the arc discharge, one can unhesitatingly place several spark gaps in series, as happens in the Feussner spark source with its interruptor. The division of energy among the individual sparks is regulated.The rotating mirror photographs show the positive columns of the a.c. arc, which burn initially in the air, then later in the metal vapor. The actual breakdown at the beginning of the spark is without meaning for the radiation of the metal. The metal vapor radiates primarily from the vapor clouds, which break out of the electrodes with high speed and after the eruptions are independent of the discharge. The excitation of spark lines is not caused by the high voltages across the spark gap.In order that the individual sparks within spark train are uniform it is necessary that the voltage on the capacitor before the breakdown always be the same. The voltage on the capacitor is independent on the equalization process in the charging circuit. The equalization processes must decay rapidly, hence the charging circuit has to be damped by a resistance and its resonance frequency must lie within a certain range.With uncontrolled (“conventional”) spark sources the voltage on the capacitor depends on the condition of the spark gap. Different discharge forms can develop depending on whether the gap deionizes or the voltage recovers first. Of the uncontrollable sparks, only those with relatively slow voltage recovery (which generate groups of single sparks) appear to be useful for spectroanalysis. The resonace spark source belongs to this class. For investigations of the vaporization of the electrodes and the excitation, uncontrolled spark discharges can only be used with caution.Conclusions for the spectroanalysis are drawn. Because excitation occurs primarily in the vapour clouds, their influence must be carefully watched. Particular attention is given to the cooling on the electrode surfaces.In conclusion we would like to thank the Honorary Dr. Eng. W. Rogowski for allowing us to carry out the cathode ray oscilloscope investigations in his institute, as well as for the interest that he has shown in this work. One of us (Kaiser) is indebted with sincere thanks to Dr. G. Hansen, the director of the physical laboratories of the Carl Zeiss Company, for the constant support of this work.     

Controlled Carbon Nitride Growth on Surfaces for Hydrogen Evolution Electrodes

Efficient and low‐cost electrocatalysts for the hydrogen evolution reaction are highly desired for future renewable energy systems. Described herein is the reduction of water to hydrogen using a metal‐free carbon nitride electrocatalyst which operates in neutral and alkaline environments. An efficient, easy, and general method for growing ordered carbon nitride on different electrodes was developed. The metal‐free catalyst demonstrates low overpotential values, which are comparable to those of non‐noble metals, with reasonable current densities. The facile deposition method enables the fabrication of many electronic and photoelectronic devices based on carbon nitride for renewable energy applications.