ABSTRACT
Paper-based test film material is widely used in a variety of test instruments for different applications. The enzyme activity test paper sheet is one of the most popularly used test papers. Here we present a novel fabrication of paper-based enzyme activity test paper without cationic resin added in. The chemical pulping fibers were first beaten to different degrees (from 14.6 to 41.5°SR) with a PFI beater. After that, the fibers were modified with a cationic agent (3-chloro-2-hydroxypropyl trimethyl ammonium chloride) under the system of alkali and water solution. Finally, the test papers were made with the modified fiber by a regular paper former in lab. The results showed that beating is beneficial for the improvement of the cationization reaction which is indicated by the Zeta potential, FTIR and EDS. The main mechanisms involved are the destruction of crystalline zone, increase of free hydroxyl group and defibrillation. This hypothesis was supported by the SEM, XRD and fiber analyzer. Beating under the optimized condition, the wet strength and liquid absorbability of test paper can meet the application requirement, and the test results of enzyme activity are quite close to those of commercial test papers.
Subject(s)
Anions , Paper , Adsorption , Anions/chemistry , Wood/chemistry , Cations/chemistryABSTRACT
Dark hollow beams (DHBs) possess great potential for material processing, holography, and vortex beams, and thus designing a high-Q DHB cavity is significant for these applications. In this Letter, a method of designing and optimizing a high-Q DHB cavity based on a one-dimensional topological photonic crystal (TPhC) is proposed. Furthermore, how the structural parameters control the performance of the cavity is analyzed with the help of finite-element-method (FEM) simulation. According to the simulation results, the Q factor of the designed cavity can reach the order of 105 with only 19 periods of layers. It is critical to mention that, although increasing the layers can improve the average Q of the cavity, it will cause serious fluctuation of both the Q factor and the divergence angle of the output beam. The design method proposed in this Letter may not only help designers of future DHB lasers but also promote the applications of DHBs in various fields.
ABSTRACT
A method of designing negative curvature anti-resonant hollow-core fibers (NC-AR-HCFs) with bending resistance is proposed, by which the fundamental mode (FM) and higher-order mode (HOM) can be adjusted. An asymmetric double-ring negative curvature hollow-core fiber (ADR-NC-HCF) is proposed to verify the method. The ADR-NC-HCF achieves the FM loss of 0.8 dB/km at 1550 nm under the bending radius of 20 mm. The coupling relation between the modes in ADR-NC-HCFs is analyzed revealing the physical principle of the design method. Based on the principle, the fiber can be directionally optimized to achieve a lower loss of the FM or higher-order mode extinction ratio.
ABSTRACT
To solve the serious loss problem for central energy of the Cassegrain antenna, this paper designs a beam-shaping system, named E-A system, to convert the elliptical divergent beam with astigmatism from a laser diode into an annular collimation beam. This E-A system, comprised only of lenses with quadratic surfaces, can simultaneously realize four functions, i.e., aberration correction, beam circularization, beam collimation, and dark hollow beam generation. By adjusting the parameters, the E-A system can be used to shape elliptical astigmatic beams with different parameters. Further, the E-A system can maintain good performance at wavelengths from 500 to 1647 nm. After considering various practical factors, the transmission efficiency of the entire transmitting system can be increased to 93.91% at a wavelength of 1550 nm.
ABSTRACT
Analyzing optical antenna systems through geometrical optics is quite popular for its convenience, which, however, may cause remarkable errors. This paper uses both geometrical optics and diffraction theory to analyze the performance of a traditional optical antenna system, and the results calculated through the two methods are carefully compared. Based on the comparison, it shows the situations in which geometric optics will cause significant errors. In addition, a parameter γ is defined to quickly determine whether geometrical optics is suitable for analyzing optical antenna systems under some situations. This paper can help engineers quickly choose the proper method for designing and analyzing optical antenna systems.
ABSTRACT
The ray transfer matrix method is widely used for analyzing beam-transmission properties and designing multi-pass systems. In this paper, a modified ray transfer matrix method is proposed for tracing an accurate non-sequential ray in three-dimensional space based on a vector reflection theory. The modified ray transfer matrix method can be utilized to analyze a ray transmitting between arbitrary surfaces, which is not confined to rotational symmetrical structures. There is no need to project rays onto two perpendicular planes, nor to introduce a paraxial approximation in our calculation. Since the length and angle of every ray can be calculated accurately, almost no deviation is accumulated in multi-pass system. The modified ray transfer matrix method can be applied in optical design, especially in the design of multi-pass cavities and multi-pass cells.
ABSTRACT
In this paper, the propagation properties of the Laguerre-Gaussian (LG) beam passing through Cassegrain antenna system in a turbulent atmosphere have been researched. The accurate analytical function for the diffraction field of LG beam passing through Cassegrain antenna, the average intensity, and the cross-talk among different orbital angular momentum (OAM) modes of LG beam passing through Cassegrain antenna in Kolmogorov turbulent have been derived. The simulation results show that LG beam with ring-like distribution is selected to enhance the emission efficiency of Cassegrain antenna. The cross-talk among different OAM modes can remarkably reduce through using Cassegrain antenna. The analysis process can also apply to accurately analyzing the propagation properties of other kinds of beams through different optical systems in turbulent atmosphere.
ABSTRACT
With the improvement of the transmission efficiency, the Cassegrain antenna can be widely used in space optical communication. In this paper, the Bessel-Gaussian (BG) beam is used to avoid the central energy loss of a Cassegrain antenna system. The intensity distribution and the phase distribution of the BG beam passing through a Cassegrain antenna are theoretically derived and simulated. At a wavelength of 1550 nm, this method can theoretically improve the transmission efficiency to approach 100% under the situation in which the obscuration ratio is nonzero, and the transmission efficiency can reach more than 80% when obscuration ratio is in the range of from 0 to 0.1252 with $l=4$l=4. The effects of on-axial defocusing on the light field and the transmission efficiency are studied. The method proposed in this paper can remarkably improve the transmission efficiency of a Cassegrain antenna in a practical and uncomplicated approach.
ABSTRACT
The aim of this work was to study the sedimentary substances formed on the surface of auto-hydrolyzed wood chips. And its potential effect on the subsequent chemical pulping was then investigated by the analysis of surface morphology, benzene-alcohol extractive, absorbability and kraft pulping of wood chips hydrolyzed. The results showed that sediments on the surface of auto-hydrolyzed wood chips were microspheric and the amount of them increased with intensifying the severity of treatment. The benzene-alcohol extractives and lignin content in the extractives increased from 1.36% and 16.42% in the control sample to 9.42% and 47.68% in the hydrolyzed wood chips at the P-factor of 808. The absorbability of hydrolyzed wood chips firstly improved in the early stage (P-factorâ¯<â¯306) and after then decreased. Negative effect of the sediments on the surface of hydrolyzed wood chips was found on the subsequent kraft chemical pulping and the properties of final pulp.
Subject(s)
Acacia , Wood , Benzene , Hydrolysis , LigninABSTRACT
Central energy loss is a critical factor decreasing the transmission efficiency of a Cassegrain antenna. In this paper, a pair of conic lenses are designed and set in front of a Cassegrain antenna to improve the transmission efficiency of the antenna instead of designing a complicated antenna structure. On the basis of the analysis, the optimized conic lens pair can theoretically improve the transmission efficiency up to 100% at a wavelength of 1550 nm under ideal conditions. After several practical factors are considered, such as the dispersion of the material, the transmissivity and chamfering of the conic lens, and the reflectivity of the mirrors composing the Cassegrain antenna, the conic lens pair can still increase the transmission efficiency of the Cassegrain antenna up to 92.37% at a wavelength of 1550 nm. Compared with designing a complicated antenna, the method proposed here provides a more practical approach to improve the transmission efficiency of a Cassegrain antenna.
ABSTRACT
When using a combination of pre-extraction and chemical pulping, a high yield of sugar recovery and minimal negative effect on the subsequent pulping step are expected. In this work, the P factor was utilized to investigate the effect of auto-hydrolysis severity on sugar recovery, removal of the main component, and impact on the kraft pulping of acacia wood chips. Using a P factor of 235, 84.34% of the polysaccharides in 14.05 g L-1 of dissolved sugars could be obtained. In addition, the soluble sugars were easily separated with a recovery yield of 3.54 g ·L-1 and Mw of 4,690 g mol-1 by direct precipitation using organic solvents. However, a maximum of 22.14 g L-1 of dissolved sugars was obtained with approximately 72.53% polysaccharides and Mw of 2,198 g mol-1 for a P factor of 601. Moreover, nearly 50% of the degraded carbohydrates remained in the auto-hydrolyzed wood chips. The decrease in the mass of pentosan, holocellulose, and klason lignin was 62, 30, and 8.76%, respectively. With intensifying severity, the screened yield and viscosity of pulps decreased markedly, whileas the Kappa number increased. No significant differences were observed in the morphology of the resultant fibers. Moreover, there was a decrease in the physical strength of the pulps due to the loss of the intrinsic strength of the pulp fibers, which in turn resulted from the cellulose damage. The combustion performance of the resultant pulping black liquor is improved due to the higher lignin content.
