An Optical System of Star Sensors with Accuracy Performance Varying with the Field of View.

The field of view and single-star measurement accuracy are crucial metrics for assessing the performance of a star sensor. The field of view determines the spatial range of stars that can be captured by the sensor, while the single-star measurement accuracy determines the precision of attitude determination and control for the star sensor. The optical system of conventional star sensors is constrained by imaging relationships. Once the detector is determined, improving either the field of view or the single-star measurement accuracy will result in the degradation of the other. To address this issue, we propose an optical system for star sensors with accuracy performance varying with the field of view. By controlling the relationship between the field focal length of the optical system and the field of view, it is possible to simultaneously enhance both the field of view and the single-star measurement accuracy. We have designed corresponding optical systems to address the requirements for improving the single-star measurement accuracy and field of view. The design results confirm the feasibility of this star sensor. The star sensors are capable of simultaneously meeting the requirements for star pattern recognition and attitude determination, presenting broad application prospects in fields such as space navigation.

Luteolin attenuates lupus nephritis by regulating macrophage oxidative stress via HIF-1α pathway.

Lupus nephritis (LN) is a serious complication of systemic lupus erythematosus (SLE) and a leading cause of mortality. Luteolin (LUT), a compound found in many vegetables, fruits, and Chinese herbal medicine, has been shown to possess anti-inflammatory, antioxidant, and immunosuppressive properties. However, the mechanisms underlying LUT's potential therapeutic effects on LN remain unclear. In this study, we investigated LUT's antagonistic effects on inflammation and oxidative stress using MRL/lpr mice and H2O2-treated macrophages (Raw264.7). Our results indicate that LUT can ameliorate pathological abnormalities and improve renal function in MRL/lpr mice by reducing renal oxidative stress and urinary protein levels. Furthermore, we found that the Hypoxia-inducible factor 1α (HIF-1α) pathway is involved in the process of LUT improving renal injury in lupus mice. Analysis of GEO data confirmed that HIF-1α expression is significantly elevated in the kidneys of LN patients, and our experiments conducted in vitro and in vivo indicate that infiltrating macrophages contribute to the elevated levels of HIF-1α expression in the kidney. By inhibiting HIF-1α expression and oxidative stress in macrophages, LUT can mitigate renal damage caused by infiltrating macrophages. In conclusion, our findings suggest that LUT may serve as a potential therapeutic option for the prevention and treatment of LN by suppressing HIF-1α expression in macrophages.

Reflective astronomical telescopes with a large field of view and a wide wave band.

Large-aperture ground-based astronomical telescopes are expected to have a large field of view (FoV) and a wide working wave band. We design two coaxial reflective telescopes based on a low-order even asphere and a high-order Q-con polynomial. Both telescopes have a primary mirror with a diameter of 6.5 m, a focal length of 24 m, and a working wavelength that stretches from ultraviolet to near-infrared (0.365-2.4 µm). The telescopes using an asphere and a Q-con polynomial have spectroscopic-survey fields of 3° and 3.4°, respectively. In these fields, the EE80D (diameter of 80%-enclosed light energy) values that can characterize the telescope image quality is less than 0.58'', and the spectral data can be obtained using fibers at the focal surface of the telescopes. Additionally, the two reflective telescopes can image celestial targets in a 0.4° FoV, and the root mean square diameters of the standard spot diagrams are less than 27 µm. By combining precise imaging measurements with the spectral data, the properties of celestial bodies can be better analyzed. The designed telescopes could enable the realization of astronomical spectroscopic surveys with both a large FoV and a wide waveband.

Detection and Genotyping of Francisella tularensis in Animal Hosts and Vectors from Six Different Natural Landscape Areas, Gansu Province, China.

OBJECTIVE: Tularemia, also known as hare fever, is caused by the bacterium Francisella tularensis (F. tularensis) transmitted through diseased wild animals, blood sucking insects, or contaminated water or food, which is distributed worldwide. The purpose of this study was to investigate F. tularensis infection in animal hosts and vectors from six different natural landscape areas in Gansu Province and to identify the genotypes of the detected F. tularensis. METHODS: Rodents were captured by snap traps, and ticks were collected by dragging a cloth over the vegetation or from domestic animals. After species identification, DNA was isolated from the captured animals and detected by nested PCR assays targeting the F. tularensis fopA gene. The positive samples were further amplified to discriminate the species, and another two short-sequence tandem repeat regions (SSTR) were amplified to identify their genotypes. All positive fragments were sequenced and analyzed by ClustalX (5.0) and DNAClub software. RESULTS: A total of 407 rodents of 12 species were captured, among which six rodent species were positive for F. tularensis, with an overall prevalence of 3.93%. The geographical difference in infection rate was statistically significant. At the SSTR9 locus, there were 7 genotypes among positive rodent samples. A total of 1864 ticks were tested for evidence of tularemia by nested PCR assays, 69 of which were positive, with an average positive rate of 3.70% for F. tularensis in ticks. The positive rates were significantly different among different regions. Seven genotypes were identified at the SSTR9 locus, one of which seemed dominant in positive tick samples. All positive samples had the same genotype at the SSTR16 locus. CONCLUSION: There is natural infection of F. tularensis among animal vectors and hosts in Gansu Province, with diverse genotypes.

Prediction of protein structural classes by different feature expressions based on 2-D wavelet denoising and fusion.

BACKGROUND: Protein structural class predicting is a heavily researched subject in bioinformatics that plays a vital role in protein functional analysis, protein folding recognition, rational drug design and other related fields. However, when traditional feature expression methods are adopted, the features usually contain considerable redundant information, which leads to a very low recognition rate of protein structural classes. RESULTS: We constructed a prediction model based on wavelet denoising using different feature expression methods. A new fusion idea, first fuse and then denoise, is proposed in this article. Two types of pseudo amino acid compositions are utilized to distill feature vectors. Then, a two-dimensional (2-D) wavelet denoising algorithm is used to remove the redundant information from two extracted feature vectors. The two feature vectors based on parallel 2-D wavelet denoising are fused, which is known as PWD-FU-PseAAC. The related source codes are available at https://github.com/Xiaoheng-Wang12/Wang-xiaoheng/tree/master. CONCLUSIONS: Experimental verification of three low-similarity datasets suggests that the proposed model achieves notably good results as regarding the prediction of protein structural classes.

Extremely wide-angle lens with transmissive and catadioptric integration.

Wide-angle lenses can be generally classified into two structures: a transmitted fish-eye structure and a catadioptric structure with a panoramic annular lens (PAL). Compared with the former, the latter exhibits better imaging capability for a super-large field of view. However, the PAL causes this type of optical system to lose its imaging ability in a small field of view in front of the lens. In this study, a novel extremely wide-angle lens is designed by combining the fish-eye and catadioptric structures. The designed lens integrates the transmissive and catadioptric structures and can simultaneously observe two fields of view. The two fields of view of the lens complement each other and completely eliminate the central observation blind area of ordinary catadioptric wide-angle lens. The forward field of view of the lens is 360°×(0°-56°), and the annular field of view is 360°×(55°-115°). The total field of view of the optical system reaches 230° when only spherical lenses are used for all the optical elements. The optical model shows that the imaging quality of the extremely wide-angle lens is good, which proves the advantages of the new optical system in a large field of view.

Apochromatic lens design in the short-wave infrared band using the Buchdahl dispersion model.

Chromatic aberration is an important artifact that influences image quality. Thus, it should be optimized during lens design. However, the typical combination and selection method of glass materials for the visible band can hardly satisfy the apochromatic requirements of short-wave infrared (SWIR) lenses. Therefore, we propose a method of glass selection for apochromatic lens design in the SWIR band through vector operation based on the Buchdahl model and third-order aberration theory. The proposed method overcomes limitations of traditional methods and unstable calculation results of special material properties. A design example is presented, which indicates that the proposed method can correct the secondary spectrum in the SWIR band and simplify the design using ordinary mass-produced glasses.

Optical design of double-grating and double wave band spectrometers using a common CCD.

A new type of optical system comprising double-grating and double wave band spectrometers is designed for atmospheric detection. The optical system can bring oxygen A band (758-778 nm) and water vapor absorption band (758-880 nm) on a charge-coupled device (CCD) at the same time for ultrahigh resolution spectrum measurement. Each absorbed band with three observation directions of atmospheric radiation is imaged in different positions of a common CCD. The spectral resolution is less than 0.07 nm in oxygen A band (758-778 nm), and the spectral resolution is less than 0.28 nm in water vapor absorption band (758-880 nm). Three end faces of the optical fiber are on the slit plane for each wave band, and each end face corresponds to an observation angle. The optical fiber core diameter is 600 µm, the slit width is 25 µm, and the slit length is 18.4 mm. The principle of smile correction is analyzed. The smile of the Czerny-Turner double-grating spectrometer can be compensated by using the tilt field lens in front of the focal plane. The design results corroborate that the maximum smile of the double-grating spectrometer is 5 µm and that the approach of correcting smile is effective. The stray light is analyzed, and the approaches of suppressing the stray light are proposed.

Optical system design of an atmospheric detector with nadir view and omnidirectional limb view.

A new type of optical system for atmospheric detection is designed by using the principle of panoramic imaging. Compared to the traditional ones, this optical system can observe nadir view and omnidirectional limb view at the same time, thus improving the efficiency and accuracy of the observation data inversion. The optical system consists of a front lens group, a panoramic annular lens, a relay lens group, and a narrowband filter. The nadir view and limb view are shared with the panoramic annular lens and the relay lens group. The narrowband filter is employed to select the specific band and restrain the stray light outside the band. This detector can monitor atmosphere conditions in the nadir field of view of 10° and the limb field of view of 360°×(70.9°-73.3°). Based on this optical design, we develop a prototype for the detector and use it for the field test. The results of experiments verify the feasibility of the optical system design.

Combined effects of elevated temperature and CO2 concentration on Cd and Zn accumulation dynamics in Triticum aestivum L.

A simulated climate warming experiment was conducted to evaluate the combined effects of elevated temperature and CO2 concentration on the bioaccumulation, translocation and subcellular distributions of Cd and Zn in wheat seedlings (Triticum aestivum L. cv. Xihan 1.) at Dingxi, Gansu Province, China. The objective was to find evidence that global climate change is affecting the bioaccumulation of Cd and Zn in T. aestivum L. cv. Xihan 1. The results showed that compared to control A, elevated temperature and CO2 increased Cd bioaccumulation in the shoots by 1.4-2.5 times, and increased that in the roots by 1.2-1.5 times, but decreased Zn levels in wheat shoots by 1.4-2.0 times, while decreased that in the roots by 1.6-1.9 times. Moreover, temperature and CO2 concentration increase also led to increased Cd concentration, and decreased Zn concentration in subcellular compartments of wheat seedlings. The largest Cd concentration increase (174.4%) was observed in the cell wall and debris fractions of shoots after they were subjected to the highest CO2 and temperature treatment (TC3). The largest Zn concentration decrease (53.1%) was observed in the soluble (F3) fractions of shoots after they were subjected to the medium CO2 and temperature treatment (TC2). The temperature and CO2 increase had no significant effect on the proportional distribution of Cd and Zn in the subcellular fractions. The root-to-shoot translocation of Cd increased with the increasing temperature and CO2 concentration. However, the Zn distributions only fluctuated within a small range.

[Effect of humidity on emission of formaldehyde from blockboard].

OBJECTIVE: To study the effect of humidity on emission of formaldehyde from blockboard. METHODS: A 0.25 m3 of simulation chamber was used to explore the emission of formaldehyde from blockboard under different conditions of humidity. The temperatures of simulation chamber were kept at the degrees of 23 +/- 0.1, the velocity of ventilation of 1.0 L/min, the loading factor of (1 +/- 0.03) m2/m3. RESULTS: The chamber concentrations of formaldehyde varied with times at the conditions of different humidities matched the hyperbolic logarithm relation. The chamber concentration of formaldehyde raised remarkably when the humidity were more than 60%. The chamber stabilization concentrations of formaldehyde varied with humidity matched the index exponent relation. Equation of curve was Y = 1.34 + 0.23e(3.30) x (R2 = 0.99). CONCLUSION: The humidity could have an great effect on emission of formaldehyde from blockboard.