Compact on-chip crystalline resonator integration with etching of tapered fiber waveguide.

Whispering-gallery-mode crystalline resonators currently maintain the best quality factor (Q) record; however, compact on-chip packaging is still a challenge, although various coupling architectures have been developed. Here, a chemical etching method is proposed to fabricate a miniaturized tapered fiber waveguide on silicon substrate. The Marangoni effect is implemented to reduce the surface roughness of the cone region. The optical loss of 0.1 dB/mm is obtained, and the Q of the on-chip crystalline resonator exceeds 108. Additionally, thermoelectric cooler (TEC) is implanted in the package to actively customize the temperature, and the temperature response of 18 pm/°C is consistent with the theoretical calculation.

Sandwich structure magnetometer with a high sensitivity and signal-to-noise ratio based on an ultrahigh-Q CaF2 resonator.

Whispering gallery mode (WGM) resonators with an ultrahigh quality (Q) factor provide an extremely high resolution for high-precision sensing. However, it is difficult to use them directly in magnetic sensors because of the transparency to the magnetic field. In this paper, a sandwich structure consisting of a neodymium iron boron magnet and calcium fluoride resonator with a Q factor of 109 is proposed. The experimental results show that, compared with the conventional magnetometer, the signal-to-noise ratio of the optical WGM magnetometer reaches 62 dB, with the direct current sensitivity of 42.59 MHz/mT and the AC sensitivity of 794p T H z -1/2 at 42 kHz.

Autotrophic degradation of sulfamethoxazole using sulfate-reducing biocathode in microbial photo-electrolysis system.

Sulfamethoxazole is a representative of sulfonamide antibiotic pollutants. This study aims to investigate the degradation pathways of sulfamethoxazole and the response of microbial communities using the autotrophic biocathode in microbial photo-electrolysis systems (MPESs). Sulfamethoxazole with an initial concentration of 2 mg L-1 was degraded into small molecule propanol within 6 h with the biocathode. Elemental sulfur (S0) was detected in the cathode chamber, accounting for 57 % of the removed sulfate. The conversion from sulfate to S0 indicated that autotrophic microorganisms might adopt a novel pathway for sulfamethoxazole removal in the MPES. In the abiotic cathode, sulfamethoxazole degradation rate was 0.09 mg L-1 h-1 with the electrochemistry process. However, sulfamethoxazole was converted to products that still contain benzene rings, including p-aminothiophenol, 3-amino-5-methylisoxazole, and sulfonamide. The microbial community analysis indicated that the synergistic interaction of Desulfovibrio and Acetobacterium promoted the autotrophic degradation of sulfamethoxazole. The results suggested that autotrophic microorganisms may play an important role in the environmental transformation of sulfamethoxazole.

Enhanced sulfur recovery and sulfate reduction using single-chamber bioelectrochemical system.

The aim of this study was to investigate the feasibility of sulfate removal and elemental sulfur (S0) recovery in the single-chamber bioelectrochemical system (S-BES). The performance of S-BES was compared with that of dual-chamber bioelectrochemical system (D-BES). The S-BES was constructed with graphite felt as the anode and graphite brush as the cathode. The D-BES was constructed with proton exchange membrane as the separator between anode and cathode chambers. With an applied voltage of 1.0 V and 1 g/L acetate as the substrate, the S-BES and D-BES were tested by feeding with 480 mg/L SO42- in the phosphate buffer. Results showed that the maximum current density of 37.6 ± 4.5 mA/m3 was reached in the S-BES, which was higher than that in the D-BES (i.e., 22.2 ± 2.6 mA/m3). The SO42- removal was much higher in the S-BES than in the D-BES (99.5% vs. 57.2%). In the effluent and the electrodes of S-BES, S0 was identified with Raman and X- Ray diffraction analyses. The S0 recovery on the anode was 13.7 times of that on the cathode of S-BES, indicating that S0 was mainly produced on the anode. The measured total S0 recovery reached 67.5% in the S-BES. High relative abundance of Desulfurella (47.1%) and Geobacter (26.1%) dominated the community in the anode biofilm of S-BES. The excellent performance of S-BES may be attributed to the neutral pH in the solution and the synergistic reaction between the anode and cathode. Results from this study should be useful to enhance the S-BES applications in treating wastewater containing sulfate.

Sulfate reduction and elemental sulfur recovery using photoelectric microbial electrolysis cell.

Elemental sulfur recover from sulfate-rich environment has great significance for the sustainable development of environment and energy. This study aimed to realize simultaneous sulfate reduction and elemental sulfur recovery using a novel photoelectricity microbial electrolysis cell (PMEC) under low applied voltages. At an applied voltage of 1.2 V, the sulfate reduction rate in the PMEC reached 200 ± 2.3 mg L-1 d-1, and 46.3 ± 7.9% of the reduced sulfate converted to elemental sulfur. With increasing voltages from 0.8 to 1.5 V, the sulfate reduction rates enhanced from 37.8 ± 12.4 to 236 ± 18.1 mg L-1 d-1. The recovery efficiency of elemental sulfur from removed sulfate decreased to 35% at 1.5 V, which was attributed to the higher concentration of dissolved oxygen diffusing from the anode side. Sulfate reducing bacteria (including Desulfovibrio and Desulfomicrobium) cooperated with sulfur oxidizing bacteria (including Thiomonas and Acinetobacter) for recovering elemental sulfur that could be regulated by cathode configuration. The study provided an alternative to apply solar energy in biological sulfur recovery and reduce energy consumption of wastewater treatment.

On differential photometric reconstruction for unknown, isotropic BRDFs.

This paper presents a comprehensive theory of photometric surface reconstruction from image derivatives in the presence of a general, unknown isotropic BRDF. We derive precise topological classes up to which the surface may be determined and specify exact priors for a full geometric reconstruction. These results are the culmination of a series of fundamental observations. First, we exploit the linearity of chain rule differentiation to discover photometric invariants that relate image derivatives to the surface geometry, regardless of the form of isotropic BRDF. For the problem of shape-from-shading, we show that a reconstruction may be performed up to isocontours of constant magnitude of the gradient. For the problem of photometric stereo, we show that just two measurements of spatial and temporal image derivatives, from unknown light directions on a circle, suffice to recover surface information from the photometric invariant. Surprisingly, the form of the invariant bears a striking resemblance to optical flow; however, it does not suffer from the aperture problem. This photometric flow is shown to determine the surface up to isocontours of constant magnitude of the surface gradient, as well as isocontours of constant depth. Further, we prove that specification of the surface normal at a single point completely determines the surface depth from these isocontours. In addition, we propose practical algorithms that require additional initial or boundary information, but recover depth from lower order derivatives. Our theoretical results are illustrated with several examples on synthetic and real data.

On the Duality of Forward and Inverse Light Transport.

Inverse light transport seeks to undo global illumination effects, such as interreflections, that pervade images of most scenes. This paper presents the theoretical and computational foundations for inverse light transport as a dual of forward rendering. Mathematically, this duality is established through the existence of underlying Neumann series expansions. Physically, it can be shown that each term of our inverse series cancels an interreflection bounce, just as the forward series adds them. While the convergence properties of the forward series are well known, we show that the oscillatory convergence of the inverse series leads to more interesting conditions on material reflectance. Conceptually, the inverse problem requires the inversion of a large light transport matrix, which is impractical for realistic resolutions using standard techniques. A natural consequence of our theoretical framework is a suite of fast computational algorithms for light transport inversion--analogous to finite element radiosity, Monte Carlo and wavelet-based methods in forward rendering--that rely at most on matrix-vector multiplications. We demonstrate two practical applications, namely, separation of individual bounces of the light transport and fast projector radiometric compensation, to display images free of global illumination artifacts in real-world environments.

Dynein-dynactin complex is essential for dendritic restriction of TM1-containing Drosophila Dscam.

BACKGROUND: Many membrane proteins, including Drosophila Dscam, are enriched in dendrites or axons within neurons. However, little is known about how the differential distribution is established and maintained. METHODOLOGY/PRINCIPAL FINDINGS: Here we investigated the mechanisms underlying the dendritic targeting of Dscam[TM1]. Through forward genetic mosaic screens and by silencing specific genes via targeted RNAi, we found that several genes, encoding various components of the dynein-dynactin complex, are required for restricting Dscam[TM1] to the mushroom body dendrites. In contrast, compromising dynein/dynactin function did not affect dendritic targeting of two other dendritic markers, Nod and Rdl. Tracing newly synthesized Dscam[TM1] further revealed that compromising dynein/dynactin function did not affect the initial dendritic targeting of Dscam[TM1], but disrupted the maintenance of its restriction to dendrites. CONCLUSIONS/SIGNIFICANCE: The results of this study suggest multiple mechanisms of dendritic protein targeting. Notably, dynein-dynactin plays a role in excluding dendritic Dscam, but not Rdl, from axons by retrograde transport.

Baboon/dSmad2 TGF-beta signaling is required during late larval stage for development of adult-specific neurons.

The intermingling of larval functional neurons with adult-specific neurons during metamorphosis contributes to the development of the adult Drosophila brain. To better understand this process, we characterized the development of a dorsal cluster (DC) of Atonal-positive neurons that are born at early larval stages but do not undergo extensive morphogenesis until pupal formation. We found that Baboon(Babo)/dSmad2-mediated TGF-beta signaling, known to be essential for remodeling of larval functional neurons, is also indispensable for proper morphogenesis of these adult-specific neurons. Mosaic analysis reveals slowed development of mutant DC neurons, as evidenced by delays in both neuronal morphogenesis and atonal expression. We observe similar phenomena in other adult-specific neurons. We further demonstrate that Babo/dSmad2 operates autonomously in individual neurons and specifically during the late larval stage. Our results suggest that Babo/dSmad2 signaling prior to metamorphosis may be widely required to prepare neurons for the dynamic environment present during metamorphosis.