Cross-site validation of lung cancer diagnosis by electronic nose with deep learning: a multicenter prospective study

BACKGROUND

Although electronic nose (eNose) has been intensively investigated for diagnosing lung cancer, cross-site validation remains a major obstacle to be overcome and no studies have yet been performed.

METHODS

Patients with lung cancer, as well as healthy control and diseased control groups, were prospectively recruited from two referral centers between 2019 and 2022. Deep learning models for detecting lung cancer with eNose breathprint were developed using training cohort from one site and then tested on cohort from the other site. Semi-Supervised Domain-Generalized (Semi-DG) Augmentation (SDA) and Noise-Shift Augmentation (NSA) methods with or without fine-tuning was applied to improve performance.

RESULTS

In this study, 231 participants were enrolled, comprising a training/validation cohort of 168 individuals (90 with lung cancer, 16 healthy controls, and 62 diseased controls) and a test cohort of 63 individuals (28 with lung cancer, 10 healthy controls, and 25 diseased controls). The model has satisfactory results in the validation cohort from the same hospital while directly applying the trained model to the test cohort yielded suboptimal results (AUC, 0.61, 95% CI: 0.47─0.76). The performance improved after applying data augmentation methods in the training cohort (SDA, AUC: 0.89 [0.81─0.97]; NSA, AUC:0.90 [0.89─1.00]). Additionally, after applying fine-tuning methods, the performance further improved (SDA plus fine-tuning, AUC:0.95 [0.89─1.00]; NSA plus fine-tuning, AUC:0.95 [0.90─1.00]).

CONCLUSION

Our study revealed that deep learning models developed for eNose breathprint can achieve cross-site validation with data augmentation and fine-tuning. Accordingly, eNose breathprints emerge as a convenient, non-invasive, and potentially generalizable solution for lung cancer detection.

CLINICAL TRIAL REGISTRATION

This study is not a clinical trial and was therefore not registered.

Fusion of memristor and digital compute-in-memory processing for energy-efficient edge computing

Artificial intelligence (AI) edge devices prefer employing high-capacity nonvolatile compute-in-memory (CIM) to achieve high energy efficiency and rapid wakeup-to-response with sufficient accuracy. Most previous works are based on either memristor-based CIMs, which suffer from accuracy loss and do not support training as a result of limited endurance, or digital static random-access memory (SRAM)-based CIMs, which suffer from large area requirements and volatile storage. We report an AI edge processor that uses a memristor-SRAM CIM-fusion scheme to simultaneously exploit the high accuracy of the digital SRAM CIM and the high energy-efficiency and storage density of the resistive random-access memory memristor CIM. This also enables adaptive local training to accommodate personalized characterization and user environment. The fusion processor achieved high CIM capacity, short wakeup-to-response latency (392 microseconds), high peak energy efficiency (77.64 teraoperations per second per watt), and robust accuracy (<0.5% accuracy loss). This work demonstrates that memristor technology has moved beyond in-lab development stages and now has manufacturability for AI edge processors.

A 4.5 μW Miniaturized 3-Channel Wireless Intra-Cardiac Acquisition System

This article presents a chip designed for wireless intra-cardiac monitoring systems. The design consists of a three-channel analog front-end, a pulse-width modulator featuring output-frequency offset and temperature calibration, and inductive data telemetry. By employing a resistance boosting technique in the instrumentation amplifier feedback, the pseudo-resistor exhibits lower non-linearity, leading to a total harmonic distortion of below 0.1%. Furthermore, the boosting technique enhances the feedback resistance, leading to a reduction in the size of the feedback capacitor and, consequently, the overall size. To make the modulator's output frequency resilient to temperature and process changes, coarse and fine-tuning algorithms are used. The front-end channel is capable of extracting the intra-cardiac signal with an effective number of bits of 8.9, while exhibiting an input-referred noise of less than 2.7 μVrms, and consuming 200 nW per channel. The front-end output is encoded by an ASK-PWM modulator, which drives an on-chip transmitter at 13.56 MHz. The proposed System-on-Chip (SoC) is fabricated in a 0.18 μm standard CMOS technology and consumes 4.5 μW while occupying 1.125 mm2.

A 5.3 pJ/Spike CMOS Neural Array Employing Time-Modulated Axon-Sharing and Background Mismatch Calibration Techniques

Inspired by the human brain, spiking neuron networks are promising to realize energy-efficient and low-latency neuromorphic computing. However, even state-of-the-art silicon neurons are orders of magnitude worse than biological neurons in terms of area and power consumption due to the limitations. Moreover, limited routing in typical CMOS processes is another challenge for realizing the fully-parallel high-throughput synapse connections compared to biological synapses. This paper presents an SNN circuit that utilizes resource-sharing techniques to address the two challenges. Firstly, a comparator sharing neuron circuit with a background calibration technique is proposed to shrink the size of a single neuron without performance degradation. Secondly, a time-modulated axon-sharing synapse system is proposed to realize a fully-parallel connection with limited hardware overhead. To validate the proposed approaches, a CMOS neuron array is designed and fabricated under a 55-nm process. It consists of 48 LIF neurons with 3125 neurons/mm ^₂ area density, power consumption of 5.3 pJ/spike, and equivalent 2304 fully parallel synapses providing a unit throughput of 5500 events/s/neuron. It proves the proposed approaches are promising to realize a high-throughput high-efficiency SNN with CMOS technology.

A Review of Emerging Electromagnetic-Acoustic Sensing Techniques for Healthcare Monitoring

Conventional electromagnetic (EM) sensing techniques such as radar and LiDAR are widely used for remote sensing, vehicle applications, weather monitoring, and clinical monitoring. Acoustic techniques such as sonar and ultrasound sensors are also used for consumer applications, such as ranging and in vivo medical/healthcare applications. It has been of long-term interest to doctors and clinical practitioners to realize continuous healthcare monitoring in hospitals and/or homes. Physiological and biopotential signals in real-time serve as important health indicators to predict and prevent serious illness. Emerging electromagnetic-acoustic (EMA) sensing techniques synergistically combine the merits of EM sensing with acoustic imaging to achieve comprehensive detection of physiological and biopotential signals. Further, EMA enables complementary fusion sensing for challenging healthcare settings, such as real-world long-term monitoring of treatment effects at home or in remote environments. This article reviews various examples of EMA sensing instruments, including implementation, performance, and application from the perspectives of circuits to systems. The novel and significant applications to healthcare are discussed. Three types of EMA sensors are presented: (1) Chip-based radar sensors for health status monitoring, (2) Thermo-acoustic sensing instruments for biomedical applications, and (3) Photoacoustic (PA) sensing and imaging systems, including dedicated reconstruction algorithms were reviewed from time-domain, frequency-domain, time-reversal, and model-based solutions. The future of EMA techniques for continuous healthcare with enhanced accuracy supported by artificial intelligence (AI) is also presented.

An accurate potential model for the a3Σu+ state of the lithium dimer

An accurate Tang-Toennies (TT) model potential is introduced to describe the interatomic potential of the lithium dimer in the a³Σ_u⁺ state. With only one well-known parameter, the ionization energy, the new model potential compares favorably with the experimentally fitted Morse/Long-range (MLR) potential of Dattani and Le Roy [J. Mol. Spectrosc., 2011, 268, 199] and is in excellent agreement with the state-of-the-art ab initio potential of Lesiuk et al. [Phys. Rev. A, 2020, 102, 062806]. With the known dispersion coefficients and the ionization energy, the new potential requires only two experimental parameters, namely the depth of the potential well D_e and its location R_e. The new potential can be extended to the region of zero separation by the united atom limit.

The development of a full range analytical interatomic potential

A chronological account is given to the development of a full range interatomic potential. Starting with a simple phenomenological model, the terms in the model are gradually modified, so that they can carry some definite physical meaning. To gain insight, a systematic, order by order interaction potential theory is developed. Conversely, this theory suggests the functional form for the potential model. At present, we have a simple interaction model that is capable of describing the van der Waals potentials of many systems from R = 0 to R→∞.

Correction: The development of a full range analytical interatomic potential

Correction for 'The development of a full range analytical interatomic potential' by X. W. Sheng et al., Phys. Chem. Chem. Phys., 2021, DOI: 10.1039/d0cp04083e.

Conformal Analytical Potential for All the Rare Gas Dimers over the Full Range of Internuclear Distances

An analytical model for the potential between two rare gas atoms at distances between R=0 to R→∞ is assumed to be conformal with the previously published potential for He_{2} [J. Chem. Phys. 142, 131102 (2015)JCPSA60021-960610.1063/1.4916740]. The potential curves of the rare gas dimers all have the same shape and only depend on the well parameters D_{e} and R_{e}. The potentials and the vibrational levels for the 11 homonuclear and heteronuclear dimers for which recent ab initio calculations are available agree, within several percent, with the ab initio results. For the other rare gas dimers, the new potential provides the first realistic estimates for the potentials.

Ten-year clinical evaluation of posterior fixed-movable resin-bonded fixed partial dentures

OBJECTIVES

Two-unit cantilevered resin-bonded fixed partial dentures (RBFPDs) offer long-term retention for anterior and premolar-sized spans. At this center, molar and longer spans have been restored with fixed-movable (FM) RBFPDs to overcome the lower retention rates of fixed-fixed RBFPDs. This retrospective study aimed to evaluate the long-term longevity and the patient-reported outcomes of posterior FM-RBFPDs.

METHODS

Posterior FM-RBFPDs that had been inserted at least five years were reviewed. Survival was "retention of the original prosthesis in mouth" and success was "survival of prosthesis and absence of complications requiring treatment intervention". Prosthesis location, number of units, insertion year, tooth/teeth replaced and operator experience were collected. Patients' acceptance to FM-RBFPDs were assessed using prosthesis satisfaction questionnaire and Oral Health Impact Profile (OHIP-49). Results were analyzed using log-rank and cox-regression tests at significance level α = 0.05.

RESULTS

One-hundred-and-one prostheses were examined. The mean observation time was 126.4 ± 32.2 months. Thirty-six (35.6%) and 63 (62.4%) FM-RBFPDs were rated as success and survival respectively. Prostheses inserted after year 2001 (n = 69) experienced 42.0% (n = 29) success and 75.4% (n = 52) survival, and its survival rate was significantly better than those inserted in or before 2001 (p = 0.01). Five- and ten-year cumulative survival probability of FM-RBFPDs inserted after year 2001 were 82.3% and 74.1% respectively. The most frequent complications were debonding among 34 (33.7%) prostheses. Patients' acceptance were high.

CONCLUSIONS

More recently inserted prostheses showed improved longevity and patients' acceptance to posterior FM-RBFPDs were high.

CLINICAL SIGNIFICANCE

Fix-Movable RBFPDs are a viable tooth replacement option in the posterior region.

Detection of Cigarette Smoke Using a Surface-Acoustic-Wave Gas Sensor with Non-Polymer-Based Oxidized Hollow Mesoporous Carbon Nanospheres

The objective of this research was to develop a surface-acoustic-wave (SAW) sensor of cigarette smoke to prevent tobacco hazards and to detect cigarette smoke in real time through the adsorption of an ambient tobacco marker. The SAW sensor was coated with oxidized hollow mesoporous carbon nanospheres (O-HMC) as a sensing material of a new type, which replaced a polymer. O-HMC were fabricated using nitric acid to form carboxyl groups on carbon frameworks. The modified conditions of O-HMC were analyzed with Scanning Electron Microscopy (SEM), Fourier transform infrared spectrometry (FTIR), and X-ray diffraction (XRD). The appropriately modified O-HMC are more sensitive than polyacrylic acid and hollow mesoporous carbon nanospheres (PAA-HMC), which is proven by normalization. This increases the sensitivity of a standard tobacco marker (3-ethenylpyridine, 3-EP) from 37.8 to 51.2 Hz/ppm and prevents the drawbacks of a polymer-based sensing material. On filtering particles above 1 μm and using tar to prevent tar adhesion, the SAW sensor detects cigarette smoke with sufficient sensitivity and satisfactory repeatability. Tests, showing satisfactory selectivity to the cigarette smoke marker (3-EP) with interfering gases CH₄, CO, and CO₂, show that CO and CO₂ have a negligible role during the detection of cigarette smoke.

Combination immunosuppressant therapy and lupus nephritis outcome: a hospital-based study

Lupus nephritis (LN) is the leading cause of mortality in lupus patients. This study aimed to investigate the treatment outcome and renal histological risk factors of LN in a tertiary referral center. Between 2006 and 2017, a retrospective observational study enrolled 148 biopsy-proven LN patients. After propensity score matching, 75 cases were included for further analysis. The classification and scoring of LN were assessed according to the International Society of Nephrology/Renal Pathology Society. Treatment response was evaluated by daily urine protein and urinalysis at two years after commencing induction treatment and the development of end-stage renal disease (ESRD). In total, 50.7% patients achieved complete remission (CR) or partial remission (PR), while 49.3% patients were categorized as nonresponders. Therapeutic responses in terms of CR/PR rates were associated with Systemic Lupus Erythematosus Disease Activity Index scores (odds ratio (OR): 1.34, 95% confidence interval (CI): 1.12-1.60, p = 0.001). Moreover, higher baseline creatinine levels (hazard ratio (HR): 2.10, 95% CI: 1.29-3.40, p = 0.003), higher renal activity index (HR: 1.30, 95% CI: 1.07-1.58, p = 0.008) and chronicity index (HR: 1.40, 95% CI: 1.06-1.85, p = 0.017) predicted ESRD. Among pathological scores, cellular crescents (HR: 4.42, 95% CI: 1.01-19.38, p = 0.049) and fibrous crescents (HR: 5.93, 95% CI: 1.41-24.92, p = 0.015) were independent risk factors for ESRD. In conclusion, higher lupus activity was a good prognostic marker for renal remission. Renal histology was predictive of ESRD. Large-scale prospective studies are required to verify the efficacy of mycophenolate in combination with azathioprine or cyclosporine in LN patients.

An accurate potential model for the a3Σu+ state of the alkali dimers Na2, K2, Rb2, and Cs2

A modified semi-empirical Tang-Toennies potential model is used to describe the a³Σ_u⁺ potentials of the alkali dimers. These potentials are currently of interest in connection with the laser manipulation of the ultracold alkali gases. The fully analytical model is based on three experimental parameters, the well depth D_e, well location R_e, and the harmonic vibrational frequency ω_e of which the latter is only slightly optimized within the range of the literature values. Comparison with the latest spectroscopic data shows good agreement for Na₂, K₂, Rb₂, and Cs₂, comparable to that found with published potential models with up to 55 parameters. The differences between the reduced potential of Li₂ and the conformal reduced potentials of the heavier dimers are analyzed together with why the model describes Li₂ less accurately. The new model potential provides a test of the principle of corresponding states and an excellent first order approximation for further optimization to improve the fits to the spectroscopic data and describe the scattering lengths and Feshbach resonances at ultra-low temperatures.

A Low Noise CMOS Readout Based on a Polymer-Coated SAW Array for Miniature Electronic Nose

An electronic nose (E-Nose) is one of the applications for surface acoustic wave (SAW) sensors. In this paper, we present a low-noise complementary metal-oxide-semiconductor (CMOS) readout application-specific integrated circuit (ASIC) based on an SAW sensor array for achieving a miniature E-Nose. The center frequency of the SAW sensors was measured to be approximately 114 MHz. Because of interference between the sensors, we designed a low-noise CMOS frequency readout circuit to enable the SAW sensor to obtain frequency variation. The proposed circuit was fabricated in Taiwan Semiconductor Manufacturing Company (TSMC) 0.18 μm 1P6M CMOS process technology. The total chip size was nearly 1203 × 1203 μm². The chip was operated at a supply voltage of 1 V for a digital circuit and 1.8 V for an analog circuit. The least measurable difference between frequencies was 4 Hz. The detection limit of the system, when estimated using methanol and ethanol, was 0.1 ppm. Their linearity was in the range of 0.1 to 26,000 ppm. The power consumption levels of the analog and digital circuits were 1.742 mW and 761 μW, respectively.

An Inductive Power and Data Telemetry Subsystem With Fast Transient Low Dropout Regulator for Biomedical Implants

This paper presents a capacitorless low-dropout (LDO) regulator with fast transient response and data reverse telemetry circuit for fully implantable wireless transmission applications. We propose a novel hybrid feedback structure using high-frequency compensation technology to achieve a rapid transient response for the LDO regulator. To reduce the size of the implant and transmit neural recordings through the same coil without interfering with power transmission, the load-shift-key (LSK) modulation technique is adopted for back data telemetry. The proposed implantable chip, fabricated using commercial 0.18 μm complementary metal oxide semiconductor technology, yielded an output power of 15 mW. Under 1.15 V operation voltage, the maximum overshoot and undershoot voltages were less than 45 mV and 55 mV, respectively, for a 15 mA full-load current whose rising and falling time were less than 100 ns. The proposed LSK transceiver uses a digitized demodulator to improve bandwidth efficiency for low carrier frequency operation.

A Battery-Less, Implantable Neuro-Electronic Interface for Studying the Mechanisms of Deep Brain Stimulation in Rat Models

Although deep brain stimulation (DBS) has been a promising alternative for treating several neural disorders, the mechanisms underlying the DBS remain not fully understood. As rat models provide the advantage of recording and stimulating different disease-related regions simultaneously, this paper proposes a battery-less, implantable neuro-electronic interface suitable for studying DBS mechanisms with a freely-moving rat. The neuro-electronic interface mainly consists of a microsystem able to interact with eight different brain regions bi-directionally and simultaneously. To minimize the size of the implant, the microsystem receives power and transmits data through a single coil. In addition, particular attention is paid to the capability of recording neural activities right after each stimulation, so as to acquire information on how stimulations modulate neural activities. The microsystem has been fabricated with the standard 0.18 μm CMOS technology. The chip area is 7.74 mm (2) , and the microsystem is able to operate with a single supply voltage of 1 V. The wireless interface allows a maximum power of 10 mW to be transmitted together with either uplink or downlink data at a rate of 2 Mbps or 100 kbps, respectively. The input referred noise of recording amplifiers is 1.16 μVrms, and the stimulation voltage is tunable from 1.5 V to 4.5 V with 5-bit resolution. After the electrical functionality of the microsystem is tested, the capability of the microsystem to interface with rat brain is further examined and compared with conventional instruments. All experimental results are presented and discussed in this paper.

Detection of third-hand smoke on clothing fibers with a surface acoustic wave gas sensor

Third-hand smoke (THS) is a new cigarette-related issue defined as the residual contamination from cigarette smoke after a cigarette is extinguished. To detect THS on three commonly used clothing fibers-wool, cotton, and polyester, we applied two methods to measure the adsorption of THS: one was the gain of mass with an analytical balance after exposure to cigarette smoke; and the other was to detect the THS chemical compounds such as nicotine and 3-ethenylpyridine with a surface acoustic wave (SAW) sensor composed of coated oxidized hollow mesoporous carbon nanospheres. In the mass measurement, the gain of mass decreased in the order wool, cotton, and polyester; the latter gain was about one tenth that of wool. In the SAW detection, the frequency shift decreased in the same order-wool, cotton, and polyester. The residence period of THS on natural fiber (wool and cotton) is greater than on synthetic polyester fiber. These two tests provide quantitative results of THS on varied clothing fibers, to assess their risk after exposure to cigarette smoke.

Suicidal drug overdose in patients with systemic lupus erythematosus, a nationwide population-based case-control study

OBJECTIVE

A four-fold increase of suicide mortality has been demonstrated in systemic lupus erythematosus (SLE) patients. Prior studies showed that the most common method of suicide attempts in SLE patients involves drug overdose. Therefore, we conducted a nationwide population-based case-control study to elucidate factors associated with drug overdose as suicide attempt in SLE patients.

METHODS

This study was based on the National Health Insurance Research Database in Taiwan. We identified all SLE patients from January 1, 2000 to December 31, 2010. Patients who had suicidal drug overdose (SDO) were selected as cases while age- and gender-matched patients who did not have SDO were selected as controls.

RESULTS

The incidence rate of SDO in SLE patients was 291 cases per 100,000 person-years, higher than that in the general population (160 cases per 100,000 person-years). In a multivariate logistic regression analysis, we observed that SDO was associated with psychiatric disorders such as depressive disorders (odds ratio: 8.36, 95% confidence interval (CI): 5.60-12.48) and insomnia (odds ratio: 2.71, 95% CI: 1.73-4.25), and lower monthly income (odds ratios: 2.74 to 3.50) in SLE patients.

CONCLUSION

SDO is associated with psychiatric disorders such as depressive disorders and insomnia, and lower monthly income in SLE patients.

Communication: A simple full range analytical potential for H2b(3)∑u (+), H-He (2)∑(+), and He2 (1)∑g (.)

The Tang-Toennies potential for the weakly interacting systems H2b(3)Σu (+), H-He (2)Σ(+), and He2 (1)Σg (+) is extended down to the united atom limit of vanishing internuclear distance. A simple analytic expression connects the united atom limiting potential with the Tang-Toennies potential in the well region. The new potential model is compared with the most recent ab initio calculations for all three systems. The agreement is better than 20% (H2 and He2) or comparable with the differences in the available ab initio calculations (H-He) over six orders of magnitude corresponding to the entire range of internuclear distances.

A bio-inspired two-layer sensing structure of polypeptide and multiple-walled carbon nanotube to sense small molecular gases

In this paper, we propose a bio-inspired, two-layer, multiple-walled carbon nanotube (MWCNT)-polypeptide composite sensing device. The MWCNT serves as a responsive and conductive layer, and the nonselective polypeptide (40 mer) coating the top of the MWCNT acts as a filter into which small molecular gases pass. Instead of using selective peptides to sense specific odorants, we propose using nonselective, peptide-based sensors to monitor various types of volatile organic compounds. In this study, depending on gas interaction and molecular sizes, the randomly selected polypeptide enabled the recognition of certain polar volatile chemical vapors, such as amines, and the improved discernment of low-concentration gases. The results of our investigation demonstrated that the polypeptide-coated sensors can detect ammonia at a level of several hundred ppm and barely responded to triethylamine.

A fully integrated nose-on-a-chip for rapid diagnosis of ventilator-associated pneumonia

Ventilator-associated pneumonia (VAP) still lacks a rapid diagnostic strategy. This study proposes installing a nose-on-a-chip at the proximal end of an expiratory circuit of a ventilator to monitor and to detect metabolite of pneumonia in the early stage. The nose-on-a-chip was designed and fabricated in a 90-nm 1P9M CMOS technology in order to downsize the gas detection system. The chip has eight on-chip sensors, an adaptive interface, a successive approximation analog-to-digital converter (SAR ADC), a learning kernel of continuous restricted Boltzmann machine (CRBM), and a RISC-core with low-voltage SRAM. The functionality of VAP identification was verified using clinical data. In total, 76 samples infected with pneumonia (19 Klebsiella, 25 Pseudomonas aeruginosa, 16 Staphylococcus aureus, and 16 Candida) and 41 uninfected samples were collected as the experimental group and the control group, respectively. The results revealed a very high VAP identification rate at 94.06% for identifying healthy and infected patients. A 100% accuracy to identify the microorganisms of Klebsiella, Pseudomonas aeruginosa, Staphylococcus aureus, and Candida from VAP infected patients was achieved. This chip only consumes 1.27 mW at a 0.5 V supply voltage. This work provides a promising solution for the long-term unresolved rapid VAP diagnostic problem.

Corresponding states principle and van der Waals potentials of Zn2, Cd2, and Hg2

Based on the assumptions that the corresponding states principle is valid for the group 12 dimers and that the interaction potentials of these dimers can be described by the Tang-Toennies potential model, a set of correlation relations between the spectroscopic constants of these dimers are derived. Some recently measured spectroscopic constants satisfy these relations quite well, but older experimental data do not. These recent spectroscopic constants and the newly available dispersion coefficients are used to construct the entire van der Waals potentials of Zn2, Cd2, and Hg2. There are indications that the ground state Hg2 potential predicted by the present study is possibly the most accurate to date. No unequivocal conclusion can be made for Zn2 and Cd2 potentials. Compared with the recent experiments, the present Zn2 bond length is eight percent too small, and the present Cd2 bond length is eight percent too large. However, both Zn2 and Cd2 bond lengths predicted by the present study are in good agreement with the quantum Monte Carlo results.

A miniature electronic nose system based on an MWNT-polymer microsensor array and a low-power signal-processing chip

This article introduces a power-efficient, miniature electronic nose (e-nose) system. The e-nose system primarily comprises two self-developed chips, a multiple-walled carbon nanotube (MWNT)-polymer based microsensor array, and a low-power signal-processing chip. The microsensor array was fabricated on a silicon wafer by using standard photolithography technology. The microsensor array comprised eight interdigitated electrodes surrounded by SU-8 "walls," which restrained the material-solvent liquid in a defined area of 650 × 760 μm(2). To achieve a reliable sensor-manufacturing process, we used a two-layer deposition method, coating the MWNTs and polymer film as the first and second layers, respectively. The low-power signal-processing chip included array data acquisition circuits and a signal-processing core. The MWNT-polymer microsensor array can directly connect with array data acquisition circuits, which comprise sensor interface circuitry and an analog-to-digital converter; the signal-processing core consists of memory and a microprocessor. The core executes the program, classifying the odor data received from the array data acquisition circuits. The low-power signal-processing chip was designed and fabricated using the Taiwan Semiconductor Manufacturing Company 0.18-μm 1P6M standard complementary metal oxide semiconductor process. The chip consumes only 1.05 mW of power at supply voltages of 1 and 1.8 V for the array data acquisition circuits and the signal-processing core, respectively. The miniature e-nose system, which used a microsensor array, a low-power signal-processing chip, and an embedded k-nearest-neighbor-based pattern recognition algorithm, was developed as a prototype that successfully recognized the complex odors of tincture, sorghum wine, sake, whisky, and vodka.

Hardware friendly probabilistic spiking neural network with long-term and short-term plasticity

This paper proposes a probabilistic spiking neural network (PSNN) with unimodal weight distribution, possessing long- and short-term plasticity. The proposed algorithm is derived by both the arithmetic gradient decent calculation and bioinspired algorithms. The algorithm is benchmarked by the Iris and Wisconsin breast cancer (WBC) data sets. The network features fast convergence speed and high accuracy. In the experiment, the PSNN took not more than 40 epochs for convergence. The average testing accuracy for Iris and WBC data is 96.7% and 97.2%, respectively. To test the usefulness of the PSNN to real world application, the PSNN was also tested with the odor data, which was collected by our self-developed electronic nose (e-nose). Compared with the algorithm (K-nearest neighbor) that has the highest classification accuracy in the e-nose for the same odor data, the classification accuracy of the PSNN is only 1.3% less but the memory requirement can be reduced at least 40%. All the experiments suggest that the PSNN is hardware friendly. First, it requires only nine-bits weight resolution for training and testing. Second, the PSNN can learn complex data sets with a little number of neurons that in turn reduce the cost of VLSI implementation. In addition, the algorithm is insensitive to synaptic noise and the parameter variation induced by the VLSI fabrication. Therefore, the algorithm can be implemented by either software or hardware, making it suitable for wider application.

Towards a chemiresistive sensor-integrated electronic nose: a review

Electronic noses have potential applications in daily life, but are restricted by their bulky size and high price. This review focuses on the use of chemiresistive gas sensors, metal-oxide semiconductor gas sensors and conductive polymer gas sensors in an electronic nose for system integration to reduce size and cost. The review covers the system design considerations and the complementary metal-oxide-semiconductor integrated technology for a chemiresistive gas sensor electronic nose, including the integrated sensor array, its readout interface, and pattern recognition hardware. In addition, the state-of-the-art technology integrated in the electronic nose is also presented, such as the sensing front-end chip, electronic nose signal processing chip, and the electronic nose system-on-chip.

An ADC-free adaptive interface circuit of resistive sensor for electronic nose system

The initial resistance of chemiresistive gas sensors could be affected by temperature, humidity, and background odors. In a sensing system, the traditional interface circuit always requires an ADC to convert analog signal to digital signal. In this paper, we propose an ADC-free adaptive interface circuit for a resistive gas sensor to read sensor signal and cancel the baseline drift. Furthermore, methanol was used to test the proposed interface circuit, which was connected with a FIGARO® gas sensor. This circuit was fabricated by TSMC 0.18 µm CMOS process, and consumed 86.41 µW under 1 V supply voltage.

A novel wireless power and data transmission AC to DC converter for an implantable device

This article presents a novel AC to DC converter implemented by standard CMOS technology, applied for wireless power transmission. This circuit combines the functions of the rectifier and DC to DC converter, rather than using the rectifier to convert AC to DC and then supplying the required voltage with regulator as in the transitional method. This modification can reduce the power consumption and the area of the circuit. This circuit also transfers the loading condition back to the external circuit by the load shift keying(LSK), determining if the input power is not enough or excessive, which increases the efficiency of the total system. The AC to DC converter is fabricated with the TSMC 90nm CMOS process. The circuit area is 0.071mm(2). The circuit can produce a 1V DC voltage with maximum output current of 10mA from an AC input ranging from 1.5V to 2V, at 1MHz to 10MHz.

A 1V low power second-order delta-sigma modulator for biomedical signal application

This paper presents the design and implementation of a low-power delta-sigma modulator for biomedical application with a standard 90 nm CMOS technology. The delta-sigma architecture is implemented as 2nd order feedforward architecture. A low quiescent current operational transconductance amplifier (OTA) is utilized to reduce power consumption. This delta-sigma modulator operated in 1V power supply, and achieved 64.87 dB signal to noise distortion ratio (SNDR) at 10 KHz bandwidth with an oversampling ratio (OSR) of 64. The power consumption is 17.14 µW, and the figure-of-merit (FOM) is 0.60 pJ/conv.

Polymer/Ordered mesoporous carbon nanocomposite platelets as superior sensing materials for gas detection with surface acoustic wave devices

We have prepared nanocomposites of polymers and platelet CMK-5-like carbon and have demonstrated their superior performance for gravimetric gas detection. The zirconium-containing platelet SBA-15 was used as hard template to prepare CMK-5-like carbon, which was then applied as a lightweight and high-surface-area scaffold for the growth of polymers by radical polymerization. Mesoporous nanocomposites composed of four different polymers were used as sensing materials for surface acoustic wave devices to detect ppm-level ammonia gas. The sensors showed much better sensitivity and reversibility than those coated with dense polymer films, and the sensor array could still generate a characteristic pattern for the analyte with a concentration of 16 ppm. The results show that the nanocomposite sensing materials are promising for highly sensitive gravimetric-type electronic nose applications.

VLSI implementation of a bio-inspired olfactory spiking neural network

This paper presents a low-power, neuromorphic spiking neural network (SNN) chip that can be integrated in an electronic nose system to classify odor. The proposed SNN takes advantage of sub-threshold oscillation and onset-latency representation to reduce power consumption and chip area, providing a more distinct output for each odor input. The synaptic weights between the mitral and cortical cells are modified according to an spike-timing-dependent plasticity learning rule. During the experiment, the odor data are sampled by a commercial electronic nose (Cyranose 320) and are normalized before training and testing to ensure that the classification result is only caused by learning. Measurement results show that the circuit only consumed an average power of approximately 3.6 μW with a 1-V power supply to discriminate odor data. The SNN has either a high or low output response for a given input odor, making it easy to determine whether the circuit has made the correct decision. The measurement result of the SNN chip and some well-known algorithms (support vector machine and the K-nearest neighbor program) is compared to demonstrate the classification performance of the proposed SNN chip.The mean testing accuracy is 87.59% for the data used in this paper.

A band-tunable, multichannel amplifier for neural recording with AP/LFP separation and dual-threshold adaptive AP detector

This article presents a low-power low-noise neural recording system comprising a set of 4-channel amplifiers and a dual-threshold adaptive action potential detector. The front-end amplifier is optimized for power efficiency, noise, and silicon area. A balanced tunable pseudo-resistor is used to acquire local field potential (LFP) and action potential (AP) separately. The post-layout simulation results show that the system achieved input referred noise 4.7 μVrms and noise efficiency factor (NEF) 2.79 with mid-band gain of 51.9 dB and power consumption of 5.22 μW. The bandwidth is highly tunable in the range of 2.38 Hz-300 Hz for high-pass corner and 248 Hz-12.9 kHz for low-pass corner, which can acquire AP and LPF without out-band noise. The proposed dual-threshold adaptive AP detector can capture action potential precisely from background activity, thus data reduction can be realized by only processing these significant waveforms. The results show that the proposed low-power, low-noise biomedical system is suitable for implantable device applications.

A single-walled carbon nanotube network gas sensing device

The goal of this research was to develop a chemical gas sensing device based on single-walled carbon nanotube (SWCNT) networks. The SWCNT networks are synthesized on Al(2)O(3)-deposted SiO(2)/Si substrates with 10 nm-thick Fe as the catalyst precursor layer using microwave plasma chemical vapor deposition (MPCVD). The development of interconnected SWCNT networks can be exploited to recognize the identities of different chemical gases by the strength of their particular surface adsorptive and desorptive responses to various types of chemical vapors. The physical responses on the surface of the SWCNT networks cause superficial changes in the electric charge that can be converted into electronic signals for identification. In this study, we tested NO(2) and NH(3) vapors at ppm levels at room temperature with our self-made gas sensing device, which was able to obtain responses to sensitivity changes with a concentration of 10 ppm for NO(2) and 24 ppm for NH(3).

A low-power electronic nose signal-processing chip for a portable artificial olfaction system

The bulkiness of current electronic nose (E-Nose) systems severely limits their portability. This study designed and fabricated an E-Nose signal-processing chip by using TSMC 0.18-μ m 1P6M complementary metal-oxide semiconductor technology to overcome the need to connect the device to a personal computer, which has traditionally been a major stumbling block in reducing the size of E-Nose systems. The proposed chip is based on a conductive polymer sensor array chip composed of multiwalled carbon nanotubes. The signal-processing chip comprises an interface circuit, an analog-to-digital converter, a memory module, and a microprocessor embedded with a pattern-recognition algorithm. Experimental results have verified the functionality of the proposed system, in which the E-Nose signal-processing chip successfully classified three odors, carbon tetrachloride (CCl4), chloroform (CHCl3), and 2-Butanone (MEK), demonstrating its potential for portable applications. The power consumption of this signal-processing chip was maintained at a very low 2.81 mW using a 1.8-V power supply, making it highly suitable for integration as an electronic nose system-on-chip.

Asymptotic exchange energy of heteronuclear dimers

A simple expression for the asymptotic exchange energy of heteronuclear dimers is derived from the surface integral method. A five-dimensional hypersurface, consisting of all spherical surfaces centered at the nucleus of the atom with higher ionization energy, more appropriate for the case where the two atoms have different ionization energies, is used in the surface integral. All integrals are carried out analytically. Compared with the exchange energy of Smirnov and Chibisov, which is also obtained from the surface integral method with a hypersurface consisting of all infinite planes perpendicular to the internuclear axis, the present result is much simpler. The exchange energies of alkali hydrides are computed as an illustration. It is shown that the present method and the method of Smirnov and Chibisov are complementary to each other.

A bio-inspired two-layer multiple-walled carbon nanotube-polymer composite sensor array and a bio-inspired fast-adaptive readout circuit for a portable electronic nose

We report a fully integrated, portable, battery-operated electronic nose system comprising a bio-inspired two-layer multiple-walled carbon nanotube (MWNT)-polymer composite sensor array, a bio-inspired fast-adaptive readout circuit, and a microprocessor embedded with a pattern recognition algorithm. The two-layer MWNT-polymer composite sensor is simple to operate, and the membrane quality can be easily controlled. These two-layer membranes have improved sensitivity and stability. The fast-adaptive readout circuit responds to the sensor response, while tuning out the long-term constant background humidity, temperature, and odors. This portable electronic nose system successfully classified four complex alcohol samples 40 times for each sample; these samples were sake, sorghum liquor, medical liquor, and whisky.

An electronic-nose sensor node based on a polymer-coated surface acoustic wave array for wireless sensor network applications

This study developed an electronic-nose sensor node based on a polymer-coated surface acoustic wave (SAW) sensor array. The sensor node comprised an SAW sensor array, a frequency readout circuit, and an Octopus II wireless module. The sensor array was fabricated on a large K(2) 128° YX LiNbO3 sensing substrate. On the surface of this substrate, an interdigital transducer (IDT) was produced with a Cr/Au film as its metallic structure. A mixed-mode frequency readout application specific integrated circuit (ASIC) was fabricated using a TSMC 0.18 μm process. The ASIC output was connected to a wireless module to transmit sensor data to a base station for data storage and analysis. This sensor node is applicable for wireless sensor network (WSN) applications.

A 1.72μW, 23.2fj/conversion step successive approach ADC for bio-medical signal acquisition

This paper presents a successive approach register (SAR) analog-to-digital converter (ADC) with a novel hybrid digital-to-analog converter (DAC) architecture: half junction splitting (J.S.) and half binary weighted capacitor DAC. This DAC maintains low power consumption of J.S. DAC and the high signal-to-noise plus distortion ratio (SNDR) of binary weighted capacitor DAC. The power dissipation of the circuit is 1.72 μW, SNDR 59.17 dB, spurious free dynamic range (SFDR) 73.39 dB, and the FOM 23.2 fj/conversion step with 0.9 V supply voltage. The proposed circuit is fabricated in TSMC 0.18 μm 1P6M CMOS process technology.

A local weighted nearest neighbor algorithm and a weighted and constrained least-squared method for mixed odor analysis by electronic nose systems

A great deal of work has been done to develop techniques for odor analysis by electronic nose systems. These analyses mostly focus on identifying a particular odor by comparing with a known odor dataset. However, in many situations, it would be more practical if each individual odorant could be determined directly. This paper proposes two methods for such odor components analysis for electronic nose systems. First, a K-nearest neighbor (KNN)-based local weighted nearest neighbor (LWNN) algorithm is proposed to determine the components of an odor. According to the component analysis, the odor training data is firstly categorized into several groups, each of which is represented by its centroid. The examined odor is then classified as the class of the nearest centroid. The distance between the examined odor and the centroid is calculated based on a weighting scheme, which captures the local structure of each predefined group. To further determine the concentration of each component, odor models are built by regressions. Then, a weighted and constrained least-squares (WCLS) method is proposed to estimate the component concentrations. Experiments were carried out to assess the effectiveness of the proposed methods. The LWNN algorithm is able to classify mixed odors with different mixing ratios, while the WCLS method can provide good estimates on component concentrations.

A low-noise low-power amplifier for implantable device for neural signal acquisition

This paper presents a low-noise low-power amplifier for implantable device for neural signal acquisition. By operating MOS transistors in the subthreshold region, smaller low-frequency noise and lower power consumption can be achieved. A low power, low-noise common-drain buffer and a low-noise, high-linearity, low pass filter are used for high frequency noise filtering. Post-layout simulation shows the input referred noise of the system is 2.19microVrms from 10Hz to 10 KHz, power consumption is 55.8microW, and the NEF is 2.53. The amplifier was fabricated using a TSMC 0.18microm 1P6M CMOS process. Simulation results show that this low-noise, low-power amplifier is suitable for implantable device applications.

Declines in tobacco brand recognition and ever-smoking rates among young children following restrictions on tobacco advertisements in Hong Kong

BACKGROUND

We compared the recognition of tobacco brands and ever-smoking rates in young children before (1991) and after (2001) the implementation of cigarette advertising restrictions in Hong Kong and identified continuing sources of tobacco promotion exposure.

METHODS

A cross-sectional survey of 824 primary school children aged from 8 to 11 (Primary classes 3-4) living in two Hong Kong districts was carried out using self-completed questionnaires examining smoking behaviour and recognition of names and logos from 18 tobacco, food, drink and other brands common in Hong Kong.

RESULTS

Ever-smoking prevalence in 2001 was 3.8 per cent (1991, 7.8 per cent). Tobacco brand recognition rates ranged from 5.3 per cent (Viceroy name) to 72.8 per cent (Viceroy logo). Compared with 1991, in 2001 never-smoker children recognized fewer tobacco brand names and logos: Marlboro logo recognition rate fell by 55.3 per cent. Similar declines were also seen in ever-smoker children, with recognition of the Marlboro logo decreasing 48 per cent. Recognition rates declined amongst both boys and girls. Children from non-smoking families constituted 51 per cent (426) of the sample, whereas 34.5 per cent (284), 8.5 per cent (70), 1.7 per cent (14) and 4.4 per cent (36) of the children had one, two, three or more than three smoking family members at home, respectively. Tobacco brand recognition rates and ever-smoking prevalence were significantly higher among children with smoking family members compared with those without. Among 12 possible sources of exposure to cigarette brand names and logos, retail stalls (75.5 per cent; 622), indirect advertisements (71.5 per cent; 589) and magazines (65.3 per cent; 538) were ranked the most common.

CONCLUSION

Advertising restrictions in Hong Kong have effectively decreased primary-age children's recognition of tobacco branding. However, these children remain vulnerable to branding, mostly through exposure from family smokers, point-of-sale tobacco advertisement and occasional promotions. Action to curb these is now required.

Stimulation of hyaluronan synthesis by interleukin-1beta involves activation of protein kinase C betaII in fibroblasts from patients with Graves' ophthalmopathy

Hyaluronan accumulation in the retroorbital connective tissue is one of the pathological features of Graves' ophthalmopathy. Interleukin-1beta (IL-1beta) is known to stimulate hyaluronan synthesis in orbital fibroblasts. In the present study, the intracellular signal transduction pathways involved in this stimulatory effect were investigated in cultured human retroorbital fibroblasts from patients with Graves' ophthalmopathy. IL-1beta-induced hyaluronan synthesis was significantly inhibited by pretreatment of the cells with two protein kinase C (PKC) inhibitors, chlerythrine chloride and H-7. In addition, treatment with phorbol 12-myristate 13-acetate (PMA), a direct PKC activator, also resulted in increased hyaluronan production. IL-1beta- or PMA-stimulated hyaluronan synthesis was blocked by the protein synthesis inhibitor, cycloheximide. Moreover, the intracellular Ca(2+) concentration of the orbital fibroblasts was also involved in the IL-1beta induced transduction pathway, the effect being completely inhibited by BAPTA, an internal calcium chelator. In addition, A23187, a calcium ionophore, increased hyaluronan synthesis in unstimulated cells. These results suggest that the Ca(2+)-dependent PKC signal transduction pathway plays an important role in the IL-1beta-induced hyaluronan synthesis. Moreover, IL-1beta treatment resulted in increased PKC activity and the rapid translocation of PKC betaII from the cytoplasm to the plasma membrane. These results indicate that cytosolic Ca(2+) and PKC betaII are involved in IL-1beta-induced hyaluronan synthesis in cultured orbital fibroblasts from patients with Graves' ophthalmopathy.

Pediatric eosinophilic gastroenteritis: report of one case

Eosinophilic gastroenteritis is an uncommon disease of unknown cause found particularly in children. It is characterized by the infiltration of eosinophils into the wall of the gastrointestinal tract, peripheral eosinophilia, and chronic relapsing gastrointestinal disorder. This report describes a patient with serosal eosinophilic gastroenteritis presenting ascites and peripheral eosinophilia. The diagnosis of the eosinophilic gastroenteritis was supported by sonographic analysis and dramatic clinical response to prednisolone therapy.

A point mutation in the albumin gene in a Chinese patient with familial dysalbuminemic hyperthyroxinemia

Familial dysalbuminemic hyperthyroxinemia (FDH) is an autosomal dominant disorder characterized by euthyroid hyperthyroxinemia. However, FDH has not been reported in Chinese or African patients. Here, we report the first case of FDH in a Chinese patient. A 69-year-old Chinese man was found to have increased serum total T(4) concentrations (198-242nmol/l; normal range 58-148nmol/l) and free T(4) concentrations (>58pmol/l; T(4) analog method, normal range 9-28pmol/l). Serum total T(3) and TSH concentrations were normal. The patient was misdiagnosed as hyperthyroid and was later suspected to have a TSH-producing tumor by the finding of a pituitary microadenoma, which was eventually proven to be a non-functional pituitary 'incidentaloma'. Electrophoretic analysis of the patient's serum proteins demonstrated enhanced albumin binding of [(125)I]T(4). Serum free T(4) concentrations were normal (16-19pmol/l, normal range 9-26pmol/l) when a two-step method was used. Direct sequencing of the albumin gene showed a guanine to adenosine transition in the second nucleotide of codon 218, resulting in a substitution of histidine (CAC) for the normal arginine (CGC) in one of the two alleles in the patient. The point mutation was further confirmed by HphI digestion of exon 7 of the albumin gene. The patient's son was not affected. Our studies demonstrated that the point mutation of the albumin gene in a Chinese patient with FDH was similar to that found in western white families, but differed from that in a Japanese family in whom a guanine to cytosine transition at the same position was found.

Noonan syndrome associated with moyamoya disease: report of one case

We report a patient with Noonan syndrome who had repeated transient ischemic attacks. Moyamoya was diagnosed from the image study. In addition, flunarizine therapy seems to be effective in the prevention of recurrent symptoms and signs. The association of Noonan syndrome and Moyamoya has been reported. To the best of our knowledge, this is the second case report of an association of the Noonan syndrome and Moyamoya. Further study should ensue.

Hürthle cell carcinoma of the thyroid gland with extensive tumor necrosis: a case report

Hürthle cell neoplasm of the thyroid gland is rarely associated with tumor necrosis. We report a case of Hürthle cell carcinoma of the thyroid gland with extensive necrosis. An 82-year-old man had had a right neck mass for more than 10 years. Approximately two to three weeks before he was hospitalized, this neck mass became progressively enlarged. An 131I scan could not demonstrate the right lobe of the thyroid gland, while the contralateral lobe was unremarkable. A 99mTc-sestamibi scan showed increased uptake on the lesion side. Fine needle aspiration cytology showed necrosis with macrophages in the initial aspirate, and the secondary aspirate appeared suspicious for a Hürthle cell tumor. The patient had a total thyroidectomy, and the pathology proved to be Hürthle cell carcinoma with tumor necrosis.

Primary aldosteronism due to unilateral adrenal hyperplasia: a case report

Primary aldosteronism is one of the differential diagnosis of secondary hypertension. This is usually caused by an aldosterone producing adenoma or bilateral adrenal hyperplasia which comprise about 65% and 30% of the cases, respectively. However, less than 1% of primary aldosteronism is caused by unilateral adrenal hyperplasia which is a relatively rare subset of primary aldosteronism. The clinical and biochemical manifestations of the disorder are indistinguishable from aldosterone-producing tumor, and a definitive diagnosis can only be made by pathological finding. A 33-year-old male Chinese patient presented with hypertension, hypokalemia, metabolic alkalosis, and the hypersecretion of aldosterone associated with suppressed plasma renin activity which is a typical hallmark of primary aldosteronism. Image studies including both magnetic resonance imaging (MRI) and 131I NIP-59 scan as well as postural test suggested an aldosterone-producing tumor of the right adrenal gland. Unilateral adrenectomy and pathological examination of the right adrenal gland eventually proved a case of unilateral adrenal hyperplasia. Blood pressure, plasma potassium, aldosterone and renin activity levels returned to normal two weeks after operation and had remained normal at up to one year of follow up. In addition, a saline loading test showed normal suppression of plasma aldosterone level one year after the operation, suggesting that the function of the left adrenal gland remains normal. The etiology of unilateral adrenal hyperplasia is unclear and the future recurrence of the disease is possible. Long-term follow-up is necessary to ensure the cure of this disorder.