Search

Reassessment tools of response to long-course neoadjuvant chemoradiation treatment (nCRT) in patients with locally advanced rectal cancer (LARC) are important in predicting complete response (CR) and thus deciding whether a wait-and-watch strategy can be implemented in these patients. Choosing which routine reassessment tools are optimal and when to use them is still unclear and will be researched in the study.Altogether, 250 patients with LARC who received nCRT from 2013 to 2021 and were followed up were retrospectively reviewed. Common reassessment tools of response included digital rectal examination (DRE), clinical examination and symptoms, endoscopy, biopsy, magnetic resonance imaging (MRI), and blood biomarkers.Overall, 27.20% (68/250) patients had a complete response and 72.80% (182/250) did not. The combination of MRI, endoscopy, and biopsy showed the best performance in terms of accuracy of 74% and area under the curve (AUC, 0.714, 95% CI 0.546-0.882). Reassessing through DRE and presence of symptoms failed to improve the efficacy of response reassessment. After 100 days, biopsy as an assessment tool would obtain a substantial rise in accuracy from 51.28 to 100% (p = 0.003).The combination of MRI, endoscopy, and biopsy is suitable as the reassessment tool of response for applying a wait-and-watch strategy after long-course nCRT in patients with LARC. The accuracy of biopsy as reassessment tools would be improved if they were used over 100 days after nCRT in patients with rectal cancer.

Threatened animals respond with appropriate defensive behaviors to survive. It has been accepted that midbrain periaqueductal gray (PAG) plays an essential role in the circuitry system and organizes defensive behavioral responses. However, the role and correlation of different PAG subregions in the expression of different defensive behaviors remain largely unexplored. Here, we designed and manufactured a microelectrode array (MEA) to simultaneously detect the activities of dPAG and vPAG neurons in freely behaving rats. To improve the detection performance of the MEAs, PtNP/PEDOT:PSS nanocomposites were modified onto the MEAs. Subsequently, the predator odor was used to induce the rat’s innate fear, and the changes and information transmission in neuronal activities were detected in the dPAG and vPAG. Our results showed that the dPAG and vPAG participated in innate fear, but the activation degree was distinct in different defense behaviors. During flight, neuronal responses were stronger and earlier in the dPAG than the vPAG, while vPAG neurons responded more strongly during freezing. By applying high-performance MEA, it was revealed that neural information spread from the activated dPAG to the weakly activated vPAG. Our research also revealed that dPAG and vPAG neurons exhibited different defensive discharge characteristics, and dPAG neurons participated in the regulation of defense responses with burst-firing patterns. The slow activation and continuous firing of vPAG neurons cooresponded with the regulation of long-term freezing responses. The results demonstrated the important role of PAG neuronal activities in controlling different aspects of defensive behaviors and provided novel insights for investigating defense from the electrophysiological perspective.

In order to study the fluid–solid coupling dynamic characteristics of parachute-payload system during drop process and analyze the unsteady aerodynamic characteristics under finite mass opening conditions, an adaptive moving fluid mesh method is developed on the basis of the existing arbitrary Lagrangian–Eulerian (ALE) fluid–solid coupling method. The calculation results of open force and drop velocity on the C-9 parachute demonstrate the effectiveness of this method. On this basis, the effect of canopies with three different permeability on parachute-payload system motion characteristic including opening property, steady descent property and stability is studied. Comparative analysis is conducted for structures and characteristics of vortex with different canopy materials, and interference mechanism of unsteady flow for parachute-payload system in unsteady oscillation is revealed. The results show that the adaptive moving fluid mesh method can effectively eliminate restrictions of existing simulation methods for parachute-payload system and significantly reduce calculation time. For the lightweight parachute, permeability has significant effect on kinetic characteristic of parachute-payload system. Canopy with large permeability has small opening load and structural stress in opening stage. After opening, there are mainly small vortexes distributed evenly behind the canopy with good stability. However, canopy with small permeability has obvious breath behavior and oscillation in opening stage. The main vortexes periodically shed off after opening. With the change of permeability from small to large, Parachute-payload system eventually presents three steady descent modes: conical descent, gliding descent and stable vertical descent. Graphical abstract

This paper addresses the problem of poor biometric recognition performance that is caused by greatly increased variations among the hand vein patterns of the same individuals as a result of using different imaging devices under different acquisition conditions and presents a novel solution based on two-stage coarse-to-fine matching. In particular, a global pattern descriptor is proposed as a geometrical reference for optimum image segmentation of vein patterns without significant over-segmentation and under-segmentation. In order to accommodate large cross-device variations, a control parameter is introduced to allow adjustment of segmented vein patterns, thereby enabling not only intra-class pattern similarities but also inter-class pattern dissimilarities to be increased. Furthermore, overlapping of principal vein patterns is proposed as a criterion for global coarse matching to reduce the number of candidates for identification, and distinctive efficient robust features are employed to provide a biological vision-based descriptor of salient local pattern characteristics for fine matching. Using a large dataset of 2000 cross-device hand vein images captured from two different near-infrared imaging devices and 100 hands, the efficacy of the proposed approach for a cross-device biometric system is demonstrated, with a recognition performance shown to be compatible to that of a single-device biometric system.

A dual-gas sensor system is developed for CO and CO2 detection using a single broadband light source, pyroelectric detectors and time-division multiplexing (TDM) technique. A stepper motor based rotating system and a single-reflection spherical optical mirror are designed and adopted for realizing and enhancing dual-gas detection. Detailed measurements under static detection mode (without rotation) and dynamic mode (with rotation) are performed to study the performance of the sensor system for the two gas samples. The detection period is 7.9 s in one round of detection by scanning the two detectors. Based on an Allan deviation analysis, the 1σ detection limits under static operation are 3.0 parts per million (ppm) in volume and 2.6 ppm for CO and CO2, respectively, and those under dynamic operation are 9.4 ppm and 10.8 ppm for CO and CO2, respectively. The reported sensor has potential applications in various fields requiring CO and CO2 detection such as in the coal mine.

Based on direct absorption spectroscopy (DAS), a portable methane (CH4) detection device was implemented. The device mainly includes a dual-channel non-dispersive infrared sensor (integrated with an infrared light source, light path and pyroelectric detector), a driving circuit of the sensor, an ARM11 embedded WinCE system, and a LabVIEW-based data-processing platform. Experiments were carried out with prepared CH4 samples to investigate the sensing performance. The relative detection error is less than 9.14% within the measuring range of 0—7×10-2. For a CH4 sample with concentration of 0 (i.e., pure nitrogen), the measured concentration fluctuation range is −1.2×10-5—+2×10-5. An Allan deviation analysis on the gas sample with concentration of 0 indicates that the 1σ limit of detection (LoD) of the device is 4.8×10-6 with an average time of 1 s. Experiments were performed on three CH4 samples with different concentrations to test the response time, which is validated to be less than 20 s. Due to the small size of the ARM11 embedded system and the powerful data processing capability of the LabVIEW platform, the proposed portable and miniaturized CH4 sensor shows a good application prospect in mining operations and some other industrial fields.

A novel Lagrangian interpolation-based direct laser absorption spectroscopy (LI-DLAS) technique was presented to suppress noise in infrared gas detection by incorporating Lagrangian interpolation and nonlinear least-square fitting (NLLSF). An LI-DLAS analyzer was reported for methane (CH4) detection using a 1654 nm distributed feedback (DFB) laser, a compact digital signal processor (DSP), and a multi-pass gas cell (MPGC) with a 16 m optical path length. The performance of the developed LI-DLAS CH4 analyzer was evaluated by means of laboratory experiments. Compared with the traditional DLAS-based sensor without Lagrangian interpolation, the detection sensitivity was improved from 6 ppmv to 2 ppmv, and the detection stability was enhanced as the Allan–Werle deviation was dropped from 1.514 to 0.531 ppmv for a 1 s averaging time. Compared with a DLAS analyzer based on LabVIEW platform, the DSP-based CH4 analyzer shows the merits of compact size and low cost with potential filed-deployable applications in industrial monitoring and control.

The Ti3SiC2/glass composite coatings were prepared by atmospheric plasma spraying. There are no evident microcracks between Ti3SiC2 and glass matrix due to low residual stress resulting from the matching CTE of them. The XRD patterns of the as-sprayed Ti3SiC2/glass composite coatings are composed of glass matrix, Ti3SiC2, TiC, and a small amount of Ti5Si3. The short dwell time and quite low oxygen partial pressure in plasma jet flow restrain TiC and Ti5Si3 from further oxidation. Both the real and imaginary part of the complex permittivity increase with rising Ti3SiC2 content. The coating with 25 wt% Ti3SiC2 possesses excellent microwave absorption properties. The minimum reflection loss is −47.7 dB (> 99.99 % absorption) at 10.6 GHz with a thickness of 1.4 mm and the bandwidth (

A mid-infrared carbon dioxide (CO2) sensor is presented for the application in greenhouse environment. An integrated multi-pass gas chamber and a dual-channel differential detection method are adopted to decrease response time and suppress environmental influence, respectively. An optical module is developed using a cost-effective wideband mid-infrared light source, a dual-channel pyre electrical detector and a spherical mirror, and the moisture-proof function is specially designed for enabling the application of this sensor in greenhouse with high humidity. Experiments are carried out to evaluate the sensing performance on CO2 concentration. According to the experimental results, the limit of detection (LoD) is about 3×10-5 with an absorption length of 30 cm. The relative detection error is less than 5% within the measurement range of 3×10-5—5×10-3. Based on 10 h long-term stability measurement on 5×10-4 and 2×10-3 standard CO2 samples, the maximum fluctuations are 1.08% and 3.6%, respectively. By using a 2.4 GHz wireless network communication system for remote monitoring and data recording, a field measurement of this sensor in a greenhouse is conducted, and good performance is proven in such circumstance.

By using silicon-on-insulator (SOI) platform, 12 channel waveguides, and four parallel-coupling one-microring resonator routing elements, a non-blocking four-port optical router is proposed. Structure design and optimization are performed on the routing elements at 1 550 nm. At drop state with a power consumption of 0 mW, the insertion loss of the drop port is less than 1.12 dB, and the crosstalk between the two output ports is less than −28 dB; at through state with a power consumption of 22 mW, the insertion loss of the through port is less than 0.45 dB, and the crosstalk between the two output ports is below −21 dB. Routing topology and function are demonstrated for the four-port optical router. The router can work at nine non-blocking routing states using the thermo-optic (TO) effect of silicon for tuning the resonance of each switching element. Detailed characterizations are presented, including output spectrum, insertion loss, and crosstalk. According to the analysis on all the data links of the router, the insertion loss is within the range of 0.13—3.36 dB, and the crosstalk is less than −19.46 dB. The router can meet the need of large-scale optical network-on-chip (ONoC).

As the identification technology is developed day by day, so is the counterfeit, and any accreditation system can be tricked. Therefore, a complete biometric identification system is supposed to distinguish between real and fake. Aiming at the liveness detection problems during the dorsal hand vein (DHV) recognition process, this paper proposes a method which combines principal component analysis and power spectrum estimation of the AR model together, three kinds of fake hand vein images which are paper printed, wearing thin rubber gloves and wearing thick rubber gloves have tested, and the result shows that the recognition rate of fake samples can reach 98.3 %, which proves that this method can realize in liveness detection of DHVs effectively.

By adopting a distributed feedback laser (DFBL) centered at 1.654 μm, a near-infrared (NIR) methane (CH4) detection system based on tunable diode laser absorption spectroscopy (TDLAS) is experimentally demonstrated. A laser temperature control as well as wavelength modulation module is developed to control the laser’s operation temperature. The laser’s temperature fluctuation can be limited within the range of −0.02—0.02 °C, and the laser’s emitting wavelength varies linearly with the temperature and injection current. An open reflective gas sensing probe is realized to double the absorption optical path length from 0.2 m to 0.4 m. Within the detection range of 0—0.01, gas detection experiments were conducted to derive the relation between harmonic amplitude and gas concentration. Based on the Allan deviation at an integral time of 1 s, the limit of detection (LoD) is decided to be 2.952×10-5 with a path length of 0.4 m, indicating a minimum detectable column density of ~1.2×10-5 m. Compared with our previously reported NIR CH4 detection system, this system exhibits some improvement in both optical and electrical structures, including the analogue temperature controller with less software consumption, simple and reliable open reflective sensing probe.

A parts-per-billion in volume (ppbv) level mid-infrared methane (CH4) sensor system was demonstrated using second-harmonic wavelength modulation spectroscopy (2f-WMS). A 3291 nm interband cascade laser (ICL) and a multi-pass gas cell (MPGC) with a 16 m optical path length were adopted in the reported sensor system. Two digital lock-in amplifier (DLIA) schemes, a digital signal processor (DSP)-based DLIA and a LabVIEW-based DLIA, were used for harmonic signal extraction. A limit of detection (LoD) of ~ 13.07 ppbv with an averaging time of 2 s was achieved using the DSP-based DLIA and a LoD of ~ 5.84 ppbv was obtained using the LabVIEW-based DLIA with the same averaging time. A rise time of 0→2 parts-per-million in volume (ppmv) and fall time of 2→0 ppmv were observed. Outdoor atmospheric CH4 concentration measurements were carried out to evaluate the sensor performance using the two DLIA schemes.

Biochar application is deemed to modify soil properties, but current research has been mostly conducted on the degraded land in tropical regions. Using six consecutive years of biochar field trial, we investigated effects of biochar on soil aggregates, structural stability, and soil organic carbon (SOC) and black C (BC) concentrations in aggregate fractions. The findings have important implications in managing soil structure and SOC sequestration in high fertility soils of the temperate areas. The study had four treatments: control; biochar rate at 4.5 (B4.5) and biochar rate at 9.0 t ha−1 year−1 (B9.0); and straw return (SR). Soil samples were collected from 0–10-cm layer, and aggregate size distribution was determined with the wet-sieving method. Then, the mean weight diameter (MWD) of aggregates and the aggregate ratio (AR), i.e., the ratio of the >250 μm to the 53–250 μm size were calculated to assess the structural stability. Total SOC and BC concentrations in bulk soil ( 2000, 250–2000, 53–250, and 2000, 250–2000, and 53–250 μm) and BC in extracted fractions under biochar soils were observed. These results implied that biochar addition enhanced both native SOC and BC physical protection by aggregation. Biochar application is effective in mediating soil aggregation, and thus improves both native SOC and BC stabilization in an intensive cropping system of North China.

Delafossite-type CuCr1−x Zn x O2 (x = 0, 0.03, 0.05, 0.07, 0.1) conductive oxides were synthesized by sol–gel method, and the effects of Zn-doping on morphology, structure, and electrical properties of the CuCr1−x Zn x O2 oxides were investigated. Based on X-ray diffraction (XRD) and Raman spectrum, the crystalline quality of the oxides is improved by the suitable substitution of Cr by Zn. The X-ray photoelectron spectroscopy (XPS) spectra reveal the chemical state of Zn is +2. The Hall and Seebeck coefficients of the pellet samples display a positive sign, indicating p-type conductive characteristics of the obtained oxides. The temperature-dependent resistivity of the oxides is proven to be consistent with small polaron hopping. For the three oxide samples with x = 0, 0.05, and 0.1, the activation energies for the polaron hopping between Zn2+ and Cr3+ sites are 54, 41.5, 32 meV, respectively, which is found to decrease with the increase of Zn content. The electrical conductivity can be remarkably improved by Zn-doping due to the small polaron hopping activation energy. These properties render this material promising as transparent electrode in optoelectronic industry.

A differential carbon monoxide (CO) concentration sensing device using a self-fabricated spherical mirror (e.g. light-collector) and a multi-pass gas-chamber is presented in this paper. Single-source dual-channel detection method is adopted to suppress the interferences from light source, optical path and environmental changes. Detection principle of the device is described, and both the optical part and the electrical part are developed. Experiments are carried out to evaluate the sensing performance on CO concentration. The results indicate that at 1.013×105 Pa and 298 K, the limit of detection (LoD) is about 11.5 mg/m3 with an absorption length of 40 cm. As the gas concentration gets larger than 115 mg/m3 (1.013×105 Pa, 298 K), the relative detection error falls into the range of −1.7%—+1.9%. Based on 12 h long-term measurement on the 115 mg/m3 and 1 150 mg/m3 CO samples, the maximum detection errors are about 0.9% and 5.5%, respectively. Due to the low cost and competitive characteristics, the proposed device shows potential applications in CO detection in the circumstances of coal-mine production and environmental protection.

By using poled-polymer/silicon slot waveguides in the active region and employing the Pockels effect of the poled-polymer, we propose a kind of Mach–Zehnder interferometer (MZI) electro-optic (EO) switch operated at 1550 nm. Dependencies of switching characteristics versus the slot waveguide parameters are investigated, including EO overlap integral, power ratio confined in the slot, and voltage-length product. Given the dimension of the silicon strip of 190 × 300 nm, as the slot width varies within 50–100 nm, the switching voltage can be as low as 1.0 V with only 0.17–0.35 mm active region length, and the whole device length is only about 770–950 μm. For the switch with 50 nm slot width, the insertion loss is about 4.42 dB under both operation states, and the crosstalk under cross-state and that under bar-state are about −48.2 and −65.3 dB, respectively. An impressive advantage of this switching structure lies that the voltage-length product (0.17–0.35 V mm) is at least 19–40 times smaller than that of the traditional polymer MZI EO switch (6.69 V mm). Compared with our previously reported two kinds of MZI or microring resonator assisted MZI EO switches, this switch does exhibit some superior characteristics, including low switching voltage, compact device size and small wavelength dependency, due to the use of slot waveguides in the MZI EO region.

A portable dual-channel digital/analogue hybrid lock-in amplifier (LIA) is developed, and its amplitude detection error is less than 10% when the signal-to-noise ratio (SNR) is larger than −12 dB. Then, a differential mid-infrared methane (CH4) detection device is experimentally demonstrated based on a wideband incandescence wire-source and a multi-pass spherical reflector. The experiments are carried out to obtain the sensing performance of the device. With the absorption length of only ∼4.8 cm, the limit of detection (LoD) is about 71.43 mg/m3, and the detection range is from 0 mg/m3 to 5.00×104 mg/m3. As the concentration gets larger than 714.30 mg/m3, the relative detection error falls into the range of −5%–+5%. Two seven-hour-measurements are done on the CH4 samples with concentrations of 1.43×103 mg/m3 and 4.29×103 mg/m3, respectively, and the results show that the maximum relative error is less than 5%. Because of the cost effective incandescence wire-source, the small-size and inexpensive dual-channel LIA, and the small-size absorption pool and reflector, the developed device shows potential applications of CH4 detection in coal mine production and environmental protection.

We present a differential carbon monoxide (CO) concentration sensing device using a self-fabricated spherical mirror (e.g., light collector) and a multi-pass gas chamber. Single-source dual-channel detection method is adopted to suppress the interferences from light source, optical path, and environmental changes. The detection principle of the device is described, and both the optical part and the electrical part are designed and developed. Experiments are carried out to evaluate the sensing performances on CO concentration. The results indicate that the limit of detection is about 10 ppm with an absorption length of 40 cm. As the gas concentration gets larger than 100 ppm, the relative detection error falls into the range of −1.7 to +1.9 %. Based on 12-h long-term measurements on the 100 and 1000 ppm CO samples, the maximum detection errors are about 0.9 and 5.5 %, respectively. Benefit from low cost and competitive characteristics, the proposed device shows potential applications in CO detection under the circumstances of coal-mine production and environmental protection.

One-dimensional, diluted magnetic semiconductor nanofibers have attracted increasing attention for their unique magnetic properties, large specific surface area, and high porosity. These qualities lead to excellent performance in magneto-optical devices, magnetic resonance imaging, ferrofluids and magnetic separation. The purpose of this study is to fabricate P-type one dimensional CuAlO2-based diluted magnetic semiconductor nanofibers. First, we fabricated CuAl0.95Co0.05O2 nanofibers with an average diameter of 1 μm with the electrospinning method. The annealed nanofibers were thermally treated at a temperature of 1 100 °C and then shrunk to a diameter of about 650 nm. We used X-ray diffraction measurements and Raman spectra to confirm that the CuAl0.95Co0.05O2 nanofibers had a single impurity free delafossite phase. The X-ray photoelectron spectroscopy analysis indicates that Co was present in the +2 oxidation state, resulting in an room temperature ferromagnetism in the CuAl0.95Co0.05O2 fiber. This contrasts with nonmagnetism in pristine CuAlO2 fiber. The coercivity (H c) value of 65.26 Oe and approximate saturation magnetization (M s) of 0.012 emu/g demonstrate good evidence of ferromagnetism at room temperature for CuAl0.95Co0.05O2 nanofibers.

A novel wavelet denoising (WD) assisted wavelength modulation technique is proposed for improving near-infrared detection performance on methane concentration based on tunable diode laser absorption spectroscopy (TDLAS). Due to the ability of multi-level analytical resolutions both in time- and frequency-domains, the noise contained in the differential signal is greatly suppressed. Sensor mechanical part, optical part and electrical part are integrated, and a portable detection device is finally developed. Theory and formulations of the WD-assisted wavelength modulation technique are presented, and experiments are carried out to prove the normal function on the extraction of the second harmonic (2f) signal from severely polluted differential signal by using the technique. By virtue of WD’s suppression on noises, the sensing characteristics on CH4 concentration are improved, and the limit of detection (LOD) is decreased from 4×10−6 (without WD processing) to 10−6. The proposed technique can also be used for the measurement on the concentration of other gases with corresponding near-infrared distributed feedback lasers.

Universal structure and thorough analysis are proposed for a kind of (2N + 1)th order polymer microring resonator Mach–Zehnder interferometer (MRR-MZI) electro-optic (EO) switch. Formulas and expressions of output power, insertion loss and crosstalk are derived, and detailed design and optimization are carried out. Analytical results indicate that, besides the first-order MRR-MZI EO switch (N = 0), other devices for N ≥ 1 can all perform normal switching function, and 5 ≥ N ≥ 2 is preferred for dropping the crosstalk below −10 dB. For the four MRR EO switches (N = 2–5), their switching voltages are 0.99, 0.73, 0.57 and 0.47 V, respectively; their insertion losses are within the range of 1.15–2.26 dB at bar state, whereas those are within the range of 1.95–2.42 dB at cross state; their crosstalks are within the range of 11.04–17.82 dB at bar state, whereas those are within the range of 10.34–12.51 dB at cross state. Compared with the traditional MZI EO switch, the voltage–length product (0.21 V mm) of this switching element is decreased by ~111.7 times under the same waveguide parameters. Therefore, due to small footprint size and extremely low switching voltage, this switching configuration can be densely integrated onto optoelectronic chips.

Device architecture and design scheme of a universal $$N$$ -stage cascaded polymer four-port optical router with scalable 3 $$N$$ channel wavelengths are proposed. Basic cross-coupling two-microring resonator routing element based on polymer materials is optimized for single-mode transmission, low optical loss and phase-match between microring waveguide and channel waveguide. Then, a one-stage four-port optical router is constructed using four-group basic routing elements, which has 12 possible I/O routing paths and 3 channel wavelengths. The insertion losses of each channel wavelength along every routing path are within the range of 0.04–0.63 dB, the maximum crosstalk between the on-port along each routing path and other off-ports is less than $$-39$$ dB, and the device footprint size is $$\sim $$ 0.13 mm $$^{2}$$ . Compared with the previously reported four-port silicon optical routers, this device possesses similar ring radius ( $$\sim $$ 10 $$\upmu $$ m) and device size ( $$

A 2×2 cross/bar polymer electro-optic (EO) routing switch is proposed, which is composed of two passive channel waveguides and two active EO polymer microrings with bending radius of only 13.76 μm. Detailed structure, theory and formulation are provided to characterize the output power of the switch. For obtaining fundamental mode propagation, small bending loss and phase-matching between channel waveguide and microring resonator (MRR) waveguide, the structural parameters are optimized under the wavelength of 1550 nm. Analyses and simulations on output power and output spectra indicate that a switching voltage of 5 V is desired to realize the exchange between cross state and bar state, the crosstalk under cross state and that under bar state are about −28.8 dB and −39.9 dB, respectively, and the insertion losses under these two states are about 2.42 dB and 0.13 dB, respectively. Compared with our four EO switches reported before, this device possesses ultra-compact size of 0.233 mm×0.233 mm as well as low crosstalk and insertion loss, and therefore it can serve as a good candidate for constructing large-scale optical routers or switching arrays in photonic network-on-chip (NoC).

Based on wide-band infrared (IR) light source and dual-channel pyroelectric detector with detection channel of 4.66 μm and reference channel of 3.95 μm, a differential mid-infrared (MIR) carbon monoxide (CO) detector is designed and implemented. In order to reduce the detection limit and improve the detection sensitivity, an open spherical mirror chamber is designed and fabricated according to the divergence angle of the light source. The CO detection system is established using the welded and debugged detection circuits, a series of CO gases with different concentrations are prepared, and gas concentration calibration experiment is carried out. Experimental results indicate that after the amplifying circuit, the signal-to-noise ratios (SNRs) of the two channels are 17.58 dB and 18.46 dB, respectively, and the detection error of this system is less than 9% in 0%–4% measuring range. The detection sensitivity in the low concentration range is approximately 0.05%. 6 h measurement on the 0 ppm sample gas shows that the fluctuation range is about ±0.02%, and the measurement standard deviation is about 0.89%.

Video-based face recognition is a fundamental topic in image processing and video analysis, and presents various challenges and opportunities. In this paper, we introduce an incremental learning approach to video-based face recognition which efficiently exploits the spatiotemporal information in videos. Face image sequences are incrementally clustered based on their descriptors, and the representative face images of each cluster are picked out. The incremental algorithm of creating facial visual words is applied to construct a codebook using the descriptors of the representative face images. Continuously, with the quantization of the facial visual words, each descriptor extracted from patches is converted into codes, and codes from each region are pooled together into a histogram. The representation of the face image is generated by concatenating the histograms from all regions, which is employed to perform the categorization. In the online recognition, a similarity score matrix and a voting algorithm are employed to judge a face video's identity. Recognition is performed online while face video sequence is continuous and the proposed method gives nearly realtime feedback. The proposed method achieves a 100 % verification rate on the Honda/UCSD database and 82 % on the YouTube datebase. Experimental results demonstrate the effectiveness and flexibility of the proposed method.

Generic model and thorough investigation are proposed for a novel $$1\times 2$$ polymer electro-optic (EO) switch based on one-group $$2N+1$$ vertical-turning serial-coupled microrings. For realizing boxlike flat spectrum as well as low crosstalk and insertion loss, resonance order and coupling gaps are optimized. The MRR switches with $$N \ge 1$$ reveal favorable boxlike spectrum as when compared with the simple device with only one microring ( $$N = 0$$ ). For obtaining $$

The synthesis and characterization of Fe-doped CuAlO2 semiconductor were reported. The samples were synthesized by a simple and cost effective spin-on technique from solid state reaction of Cu2O and Al2O3 on sapphire (001) substrate. Appropriate ethyl-cellulose (EC) and terpineol are useful for the formation of Fe-doped CuAlO2 films. X-ray diffraction (XRD) revealed the growth of pure delafossite CuAlO2 phase ruled out elemental metallic Fe clusters in all the Fe incorporated CuAlO2 films. The existence of ferromagnetism at room temperature is evidenced by well-defined hysteresis loops. Specially, the saturation magnetization (Ms) values at room temperature have been monotonously enhanced with the increase of Fe composition from 1% to 5%.

Presented is a compact instrument developed for in situ high-stable and sensitive continuous measurement of trace gases in air, with results shown for ambient methane (CH4) concentration. This instrument takes advantage of recent technology in thermoelectrically cooled pulsed Fabry–Perot (FP) quantum cascaded (QC) laser driving in a pulse mode operating at 7.5 μm to monitor a well-isolated spectral line near the ν4 fundamental band of CH4. A high-quality liquid nitrogen cooled mercury cadmium telluride mid-infrared detector with time discriminating electronics is used along with a total reflection coated gold ellipsoid mirror offering 20 cm single pass optical absorption in an open-path cell to achieve stability of 5.2 × 10−3 under experimental condition of 200 ppm measured ambient CH4. The instrument operates continuously, and integrated software for laser control using direct absorption provides quantitative trace gas measurements without calibration. One may substitute a QC laser operating at a different wavelength to measure other gases. The instrument can be applied to field measurements of gases of environmental concern.

By using silicon-on-insulator platform and only four parallel-coupling one microring resonator routing elements, an active non-blocking four-port optical router was theoretically proposed for large-scale optical networks-on-chip (ONoC). Through the use of thermo-optic effect of silicon for tuning the resonance of each switching element, the router can work at 9 non-blocking routing states. Structure design and optimization were performed on the routing element at 1550 nm, and the routing topology and function were demonstrated for the four-port optical router. Detailed characterization was presented, including output spectrum, insertion loss, crosstalk, and power consumption. According to the analysis on all the data links of the router, the insertion loss is within the range of 0.13–3.36 dB, the crosstalk is

A ppb-level mid-infrared ethane (C2H6) sensor was developed using a continuous-wave, thermoelectrically cooled, distributed feedback interband cascade laser emitting at 3.34 μm and a miniature dense patterned multipass gas cell with a 54.6-m optical path length. The performance of the sensor was investigated using two different techniques based on the tunable interband cascade laser: direct absorption spectroscopy (DAS) and second-harmonic wavelength modulation spectroscopy (2f-WMS). Three measurement schemes, DAS, WMS and quasi-simultaneous DAS and WMS, were realized based on the same optical sensor core. A detection limit of ~7.92 ppbv with a precision of ±30 ppbv for the separate DAS scheme with an averaging time of 1 s and a detection limit of ~1.19 ppbv with a precision of about ±4 ppbv for the separate WMS scheme with a 4-s averaging time were achieved. An Allan–Werle variance analysis indicated that the precisions can be further improved to 777 pptv @ 166 s for the separate DAS scheme and 269 pptv @ 108 s for the WMS scheme, respectively. For the quasi-simultaneous DAS and WMS scheme, both the 2f signal and the direct absorption signal were simultaneously extracted using a LabVIEW platform, and four C2H6 samples (0, 30, 60 and 90 ppbv with nitrogen as the balance gas) were used as the target gases to assess the sensor performance. A detailed comparison of the three measurement schemes is reported. Atmospheric C2H6 measurements on the Rice University campus and a field test at a compressed natural gas station in Houston, TX, were conducted to evaluate the performance of the sensor system as a robust and reliable field-deployable sensor system.

Considering that the noises resulting from low modulation frequency are serious and cannot be totally eliminated by the classic filters, a novel infrared (IR) gas concentration detection system based on the least square fast transverse filtering (LS-FTF) self-adaptive modern filter structure is proposed. The principle, procedure and simulation on the LS-FTF algorithm are described. The system schematic diagram and key techniques are discussed. The procedures for the ARM7 processor, including LS-FTF and main program, are demonstrated. Comparisons between the experimental results of the detection system using the LS-FTF algorithm and those of the system without using this algorithm are performed. By using the LS-FTF algorithm, the maximum detection error is decreased from 14.3% to 5.4%, and also the detection stability increases as the variation range of the relative error becomes much smaller. The proposed LS-FTF self-adaptive denoising method can be of practical value for mid-IR gas detection, especially for weak signal detection.

A small quantity of tributylphosphine was employed to improve the surface state of fresh and oxidized PbSe nanocrystals after the formation of nanocrystals. Experimental results showed that the photoluminescence intensity increased in both situations. However, an excessive amount of tributylphosphine exhibited negative effects of decreasing photoluminescence and particle aggregation. A suitable amount of tributylphosphine added before the synthesis of a CdSe shell on PbSe core (PbSe/CdSe) also exhibited a photoluminescence intensity increase for these core/shell nanocrystals.

Built-in electric field may enhance or retard the impurity-free vacancy disordering (IFVD) during rapid thermal annealing (RTP) by imposing a drift on charged point defects. Built-in electric field is at the interface between dielectric layer and top layer of the structure. Subsequent rapid thermal annealing leads to different intermixing results due to different field directions on InP cap layers in different doping types. Experimental results also show different influences of the built-in field on the two sublattices largely due to different charge numbers of point defects.

Niobium-doped ZnO transparent conductive films are deposited on glass substrates by radio frequency sputtering at 300°C. The influence of O2/Ar ratio on the structural, electrical and optical properties of the as-deposited films is investigated by X-ray diffraction, Hall measurement and optical transmission spectroscopy. The lowest resistivity of 4.0×10−4 Ω·cm is obtained from the film deposited at the O2/Ar ratio of 1/12. The average optical transmittance of the films is over 90%.

A novel class II 5-enoylpyruvylshikimate-3-phosphate synthase (EPSPS) was identified from Pseudomonas stutzeri A1501 by complementation of an Escherichia coli auxotrophic aroA mutant. The single amino acid substitution of serine (Ser) for asparagine (Asn)-130 of the A1501 EPSPS enhanced resistance to 200 mM glyphosate. The mutated EPSPS had a 2.5-fold increase for IC(50) [glyphosate] value, a 2-fold increase for K (i) [glyphosate] value, but a K (m) [PEP] value similar to that of wild type. The effect of the single residue mutation on glyphosate resistance was also analyzed using a computer-based three-dimensional model.

Based on different basic routing elements, device architectures and design schemes of three kinds of four-port optical routers with the same routing function are studied. First, the structural parameters of the routing elements including cross-coupling one microring resonator (CCO-MRR), cross-coupling two microring resonators (CCT-MRR) and parallel-coupling one microring resonator (PCO-MRR), are optimized for single-mode transmission, low optical loss and phase-match between microring waveguide and channel waveguide. Then, detailed routing topologies of the three routers are presented, and a thorough comparison among them is made on their routing performances. The used MRR numbers of the CCO-MRR-based and PCO-MRR-based routers (four rings) are half of that of the CCT-MRR-based router (eight rings); the PCO-MRR-based router depicts the minimum insertion loss (0.02–0.6 dB); the CCT-MRR-based router reveals the minimum crosstalk (

The glycinin G1 gene encodes a soybean seed storage protein accumulating at a high level. We have used the G1 promoter to confer seed-specific expression of human basic fibroblast growth factor (bFGF) in transgenic soybeans. The coding region of 18 kDa bFGF was fused to the promoter or promoter-signal peptide sequence of G1 gene, and transferred into soybean. Analysis of transgenic plants demonstrated that bFGF transcript or protein was confined to the seeds. The highest level of bFGF accumulation in the seeds reached up to 2.3% of total soluble protein. The soybean-derived bFGF was biologically active as confirmed by its mitogenic activity on Balb/c 3T3 cells, and exhibited other properties identical to native bFGF. We also observed a seed-specific expression of beta-glucuronidase driven by the G1 promoter. These results indicated that the G1 promoter contains essential cis-elements for seed-specific expression, and thus can be used for expression of pharmaceutical proteins in soybean seeds.

The influence of temperature and Ga composition on Auger recombination lifetime in n-type and p-type In1−x Ga x As materials is investigated through the simulation, assuming the concentrations of electrons and holes are 1017 cm−3 and 1018 cm−3, respectively. The results show that the temperature has little influence on Auger recombination lifetime of In1−x Ga x As materials at x 0.3 and the effect is more obvious at a lower temperature. Moreover, Auger recombination lifetime of p-type In1−x Ga x As is longer than that of n-type In1−x Ga x As with the same temperature, Ga composition and carriers concentration.

A theoretical model was established in this paper to analyze the properties of 3.50 and 4.39 nm PbSe quantum dot-doped liquid-core multi-mode fiber. This model was applicable to both single- and multi-mode fiber. The three-level system-based light-propagation equations and rate equations were used to calculate the guided spontaneous emission spectra. Considering the multi-mode in the fiber, the normalized intensity distribution of transversal model was improved and simplified. The detailed calculating results were thus obtained and explained using the above-mentioned model. The redshift of the peak position and the evolution of the emission power were observed and analyzed considering the influence of the fiber length, fiber diameter, doping concentration, and the pump power. The redshift increased with the increases of fiber length, fiber diameter, and doping concentration. The optimal fiber length, fiber diameter, and doping concentration were analyzed and confirmed, and the related spontaneous emission power was obtained. Besides, the normalized emission intensity increased with the increase of pump power in a nearly linear way. The calculating results fitted well to the experimental data.

Hydrophilic functionalization of nanoparticle surface is essential for their biomedical applications. Herein, we report a facile one-step reverse precipitation method to synthesize water-dispersible, biocompatible, and carboxylate-functionalized superparamagnetic magnetite (Fe3O4) nanoparticles with the help of biocompatible sodium citrate salt. Transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), zeta potential measurement, dynamic light scattering (DLS), and superconducting quantum interference device (SQUID) were used to characterize the as-prepared magnetite nanoparticles. The size of the as-prepared magnetite nanoparticles was tuned from 27 ± 3.8 to 4.8 ± 1.9 nm by changing the sodium citrate concentration from 25 to 125 mM. The sodium citrate concentration also influenced the water-dispersible stability of the as-prepared magnetite nanoparticles, which was due to the electrostatic repulsion.

In this paper, titanium doped (2 wt. %) indium oxide (TIO) thin films deposited on quartz substrates by DC sputtering were presented. Dealt with different temperatures from 420°C to 620°C of post-annealing in vacuum for 40 minuets, the samples display different optical and electric properties. The deposited films exhibited polycrystalline in the preferred (222) and (440) orientation, with higher mobility (up to 48.6 cm2/VS) and lower resistivity (1.26 ×10-4Ω·cm) at the post-annealing temperature of 520°C. The average optical transmittance of the films is over 92% in a wavelength range from 300 to 1100 nm and the transmittance has only around 1.8% change with different post-annealing temperatures.

This paper presents results for infrared transparent and conducting thin films based on In2O3. The films have been prepared by magnetrons sputtering equipment with different condition. Typical transmittance of 70%-80% with a film sheet resistance of 80-300Ω/□ in the 3.5-5.0μrn region has been achieved.Optically transparent and electrically conductive semiconductor Oxide films have been extensively studied in recent years. Such films have been prepared by various methods. In general, these films have high visible transmittance, but are opaque in the IR wavelength range of 1-12μm IR transmission. The infrared transparent and electrically conductive thin films are useful in certain important applications. For example, these films can be use as antistatic coatings, and while permitting a reasonable transmission coefficient for IR. Another obvious application is to serve as the conducting electrode for various optical devices where good infrared transmission is important. So, it is important to research indium oxide base infrared (3-5 um) transparent conduction thin films.It has been developed that preparation condition influence on properties of thin films. Such as the sputtering time, and pressure, and power, and the substrate temperature, had great influence on the crystal structure, optical and electrical properties of In2O3-based thin films.The In2O3-based thin films obtained were characterized and analyzed by X-ray Diffractometer (XRD), Atomic Force Microscope (AFM), Vander Pauw Method and Fourier Transform Infrared Spectroscopy (FTIR).

Titanium doped indium oxide (TIO) thin films were deposited on glass substrate by DC sputtering with different O2/Ar gas ratios at 330 °C. The effects of sputtering on the structural, morphologic, optical and electrical characteristics of TIO thin films were investigated by XRD, Hall measurement and optical transmission spectroscopy. The deposited films exhibited polycrystalline in the preferred (222) orientation, with higher mean grain size and lower resistivity 3.37 ×10-4Ω·cm at O2/Ar ratio of 1/10. The average optical transmittance of the films is over 90%, and the transmittance has no evident change with changing O2/Ar ratio.

Cast Mo-Mo3Si intermetallic composites develop microcracks after annealing at high temperature. Neutron diffraction, x-ray diffraction, composition analysis, and scanning electron microscopy have been used to characterize the structural changes induced by annealing of Mo-Mo3Si. It is shown that the observed cracking cannot be attributed to differential thermal stresses that developed on cooling from the annealing temperature. Instead, the experimental data suggest that the cracks were initiated at high temperature, possibly due to diffusion of Si atoms from supersaturated α-Mo to Mo3Si.