Comparative Study on Different Remediation Strategies Applied in Petroleum-Contaminated Soils.

Due to the increasing pollution by petroleum hydrocarbons (PHs), it is an important task to develop eco-friendly and highly efficient methods for remediating petroleum-contaminated soils. In this study, bioremediation technology was applied to remediate PHs contaminated soils, and the bacterial community structure and physicochemical characteristics of the soil treated using different bioremediation regimens were analyzed. Compared with the control condition (S0), the PHs removal efficiency of biostimulation (S2) and bioaugmentation (S3) was increased significantly. Combined biostimulation with bioaugmentation (S4) had the highest PHs removal efficiency, up to 60.14 ± 4.12%. Among all the selected remediation strategies (S1-S4, S1: soil moisture content: 25-30%), the bacterial alpha-diversity was higher than in S0. The genera Acinetobacter, Escherichia-Shigella, Bacteroides, Microbacterium, and Parabacteroides were found to greatly contribute to PHs' degradation. In the group S4, the PH-degraders and soil enzyme activity were higher than in the other remediation regimens, and these indices gradually decreased in the mid-to-later periods of all remediation tests. Additionally, the abundance of alkB and nah genes was increased by improving the environmental condition of the microorganism communities. Redundancy analysis (RDA) revealed that the total nitrogen (TN) and total phosphorus (TP) had a positive correlation with total PHs degradation. This study offers insights into the microbial community response to environmental factors during bioremediation, which shows a promoting effect in enhancing the efficiency of PHs remediation.

[Comparison of dispersion parts of conventional spectrometers].

Innovation of conventional spectrometers is of actual technical and economical value. It is also an important way to accelerate the development of spectroscopic instruments. When improving a conventional spectrometer, its dispersion part is pivotal, because it is decisive to the basic performance of the spectrometer. In the present paper, the typical dispersion parts of conventional spectrometers are compared to feature them and find the evolution force among them. The basic characters of the dispersion parts, including spectral range, dispersion power, resolution and throughput, are compared separately and comprehensively by reviewing their decisive factor, formula and typical data. The results not only conclude the feature and the complementariness of the dispersion parts, but also indicate that the trade-off between resolution and throughput is ubiquitous in traditional spectrometers. Further reviewing from this point, the evolution history of traditional spectrometers shows that the conflict between resolution and throughput is an important evolution force. This is a new way to understand the evolution of traditional spectrometers. Moreover, dealing with the trade-off between resolution and throughput correctly will help to analyze and settle the core problem of spectrometers.

[Global modeling and analyzing of grating spectrometers].

A method for globally modeling and analyzing grating spectrometers is put forward in the present paper. Different from existing methods which are confined to parts of a spectrometer, the method takes a grating spectrometer as four functional parts, namely imaging optics, detector, reconstruction and display. Effects of each part on spectrum are considered and a global model of the spectrometer is developed, accompanied with its transfer function. With the help of the model and the transfer function, laws of each part affecting the holistic performance are summed up. It is suggested that high quality spectrogram needs enhancing baseband response and reducing spurious response, and reconstruction is an effective way.

[Algorithm for restoring spectrogram with sub-pixel resolution].

Insufficient spatial resolution of detectors is an obstacle to capturing spectra with high resolution. An effective solution is sub-pixel restoration, which can restore a high resolution spectrogram from sub-pixel shifted low resolution ones. In the present paper, an algorithm for sub-pixel restoration is suggested. It utilizes the bidirectional recursive relation between sub-pixel values and estimates each sub-pixel value from both directions of head-end and end-head. As a result, the averaged value will be accepted as the sub-pixel value. Numerical experiments on single gauss profile and superposition ones verified the effectiveness of the algorithm.

[Blind deconvolution algorithm for spectrogram super-resolution restoration].

Deconvolution is an important way to realize spectrogram super-resolution restoration. Blind deconvolution is superior to the traditional one in that it does not need a well prepared convolution core. Taking advantages of the features of spectrogram and the existing achievements of spectrogram deconvolution, the authors bring forward a scheme to adapt the space domain iterative blind deconvolution method to spectroscopy application. Moreover, after probing into the spectrogram degradation described by convolution, computational models for spectrum convolution and Gauss fitting are worked out to meet the requirements of blind deconvolution algorithm. Accompanying results are simulations with MATLAB7.0. They shows that for the given spectrum and point spread function of Gauss type the blind deconvolution algorithm works well and a resolution enhancement of 30% can be achieved under a signal-to-noise ratio of 50 dB.

[The effect of the photoelectric detector on the accuracy of the spectrometer].

An optimized photoelectric detector will increase the precision of a spectrometer, thus indicates an important way to develop high performance spectrometer. With an eye to this, a model describing the process that spectrogram is integrated and sampled by photoelectric detector and restored after low-pass filtering is developed. Based on the model, the influence of the characteristic parameters of the detector on the spectral line in the frequency domain is analyzed and the relation between the full width half maximum (FWHM) of the spectra line and the integral interval, sampling space and sensitivity of the detector is deduced. The conclusion indicates that both the integral interval and sampling space should be 1/6 of the FWHM for a spectral line with gaussian profile as a result of compromise between accuracy and feasibility. Moreover, the critical point deciding the right situation for scanner and array detector is given. Other guide line to optimize the photoelectric detector and increase accuracy is suggested also.