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The potential dynamic risk of the mined underground space with hard overlying strata is one of the main concerns for coal operators. This paper presents a comprehensive study on treating the hard overlying strata upon the coal seam through the presplit blasting technique. The properties of the overlying strata were firstly investigated and evaluated via the laboratory tests and theoretical analysis. With the consideration of the geological and mining condition of the research area, the critical parameters of the presplit blasting technique (e.g., unsaturation coefficient, borehole spacing, and the slit width) were consequently determined via the numerical simulation with the application of LS-DYNA. Then, the field practice in accordance with the determined parameters was carried out in Yuwu coal mine. The effectiveness of the presplit blasting technique was well verified when the microstructures of the surrounding rock were investigated. The success presented in this paper does not only demonstrate the feasibility of using the presplit blasting technique in treating the hard strata of underground mines but also provide a guideline in determining the critical parameters by the numerical simulation and theoretical analysis from the design aspect.

A slit structure consisted of two bending graphene membranes is built as a nano check valve theoretically. Molecular dynamics simulations are used to investigate the opening and closing of this check valve. The backflow through the valve are also studied. The results show that the check valve can maintain the unidirectional flow of fluid and prevent backflow within the appropriate pressure range. Specifically, the opening and closing pressure of the valve are 148.2 and 24.6 MPa, respectively. The maximum working pressure of the check valve should be lower than 197.6 MPa. Moreover, the water passing rate is larger at a higher pressure due to the larger slit width and water flux. This check valve is expected to have many potential applications in the nanofluidic field.

The development of epithelial lumens in ducts is essential to the functioning of various organs and in organogenesis. Ductal elongation requires the collective migration of cell cohorts in three-dimensional (3D) confined spaces, while maintaining their epithelial integrity. Epithelial lumens generally adopt circular morphologies, however abnormalities in complex physiological environments can lead to the narrowing of glandular spaces that adopt elongated and slit-like morphologies. Here, we describe a simple method to form epithelial tissues in microchannels of various widths (100-300 µm) with a constant height of 25 µm that mimic elongated geometries of glandular spaces. The significance of this biomimetic platform has been evidenced by studying the migration of epithelial cell sheets inside these narrow slits of varying dimensions. We show that the growth of epithelial tissues in 3D-confined slits leads to a gradient of cell density along the slit axis and that the migration cell velocity depends on the extent of the spatial confinement. Our findings indicate that nuclear orientation is higher for leader cells and depends on the slit width, whereas YAP protein was predominantly localized in the nucleus of leader cells. This method will pave the way to studies aiming at understanding how 3D-confined spaces, which are reminiscent of in vivo pathological conditions, can affect the growth and the homeostasis of epithelial tissues.

A classic undergraduate introductory experiment is to measure the diffraction and interference pattern from single and double slits to determine slit width and separation. Studies show that Course-based Undergraduate Research Experiences (CUREs) can make science more inclusive when offered at the undergraduate level. Additionally, CUREs help students to understand the scientific research process. We have redesigned our diffraction and interference lab to incorporate these best-teaching practices to enhance the students’ learning experience.

The influence of the conditions of mask-based photopolymerization of thick layers of a composition (with thickness h from 0.5 to 4.0 mm) based on dimethacrylate OCM-2 and o-quinone photoinitiator on the geometry of the resulting polymer sample has been studied. Upon photopolymerization of layers through a slit aperture of width l, the polymer formed has a cross section of trapezoid, the large base of which faces to the side of illumination. With increasing exposure, the difference in the sizes of the bases of the trapezoid decreases, which reduces roughness of an object composed of such layers. For stereolithographic synthesis of a 3D model from layers with h = 0.5 and 1.0 mm and roughness of 10 μm, the minimum slit width is achieved at l ≈ 2h.

Background It has always been a great challenge for clinical doctors to reconstruct total and near-total lower lip defects. Compared with elderly patients, the repair operation in young patients is more difficult where free flaps are usually used for transfer. In order to obtain better postoperative results, the authors combined two kinds of local skin flaps for operation purpose, and evaluated their postoperative clinical effects. Methods From April 2011 to May 2019, a total of 5 young patients with lower lip tumor or trauma were included in this study, with an average age of 30.4 years old. The lesion was all resected and resulted in a defect of 87% to total area of the lower lip, accompanied by a partial defect of the chin each. To repair the defect of the lower lip, the authors firstly used the modified Bernard flap. Then the authors designed the double Abbe flap to perform the operation according to the recovery of the patient 3 months later than the first operation. Finally, the outcomes of either operation were compared upon slit width, mouth opening height, aesthetics, and function of the patients, and statistically analyzed the results. Results All patients underwent the repair of modified Bernard flaps and double Abbe flaps of with no hemodynamic disorder of the flaps and well-recovery. At 3 months after the operation, the average gap width of lip was 4.34 ± 0.24 cm, the average opening height was 3.18 ± 0.28 cm, the average aesthetic score was 7.98 ± 0.51 (full score of 10), and the average functional score was 11.4 ± 0.55 (full score of 12). The 5 patients showed no obvious scar but a good shape on the lower lip. The function of eating, pronunciation, expression of feelings and smiling change were close to normal. Three patients had mild numbness in the lower lip, while the other two had normal sensory function. Conclusion Combined modified Bernard flap and double Abbe flaps can bring out promising reparative outcomes of near-total or total lower lip defects in lower lip in young patients with good aesthetic and functional recovery, which is recommended while considering surgical alternatives.

PURPOSE After many years in clinical practice, the authors found that the long-term aesthetics of the upper lip and nose following repair of a unilateral cleft lip deformity using the Huaxi method remained unsatisfactory. The immediate postoperative effect was often good, while the long-term postoperative effect was poor. Therefore, this study aimed to evaluate the characteristics and influencing factors of a modified Huaxi method for repairing unilateral cleft lip over time, and to explore the relationship between immediate and long-term outcomes after cleft lip surgery. METHODS Patients with unilateral cleft lip who visited the Department of Maxillofacial Surgery of the Stomatological Hospital of Zunyi Medical University from June 2014 to March 2016 were selected. The study group consisted of 51 consecutive patients (30 boys and 21 girls), aged between 3 months and 2 years. Of these, 24 presented with complete unilateral cleft lip (12 wore a nasoalveolar mold as required, 12 did not) and 27 with incomplete unilateral cleft lip (13 wore a nasoalveolar mold as required, 14 did not). Photographs were taken of 51 patients before surgery and immediately, 7 days, and 6 months postoperatively. Various indexes of nasolabial contour of each patient were measured using iWitness photogrammetry, and the slit width; lip height ratio, lip width ratio, nostril width ratio, and nostril height ratio of the healthy side; and degree of deviation of the nasal columella were calculated. RESULTS Long-term symmetry of lip height and width remained stable postoperatively (P > 0.05), whereas nostril height symmetry was significantly reduced (P > 0.05). Nasal width symmetry and midpoint deviation of the nasal columella were stable in patients with nasoalveolar molding (P > 0.05), but significantly decreased in patients without nasoalveolar molding (P

Two specimens of nonductile reinforced concrete (RC) frame (ND-1) and nonductile RC frame retrofitted by corrugated steel plate shear walls slotted with columns (ND-2) are established by finite element. These specimens have same dimensions and steel skeletons. Finite element models had been verified by the existing experimental results. The hysteresis curves, skeleton curves, ductility, and stiffness curves of Specimen ND-1 and Specimen ND-2 are compared. The results show that the reinforcement effect is significant. Twenty-four models are built to study the seismic behavior on different influence parameters. The parameters are slit width, thickness of corrugated steel plate shear walls, concrete strength of nonductile RC frame, and boundary conditions of corrugated steel plate shear walls at slotted parts. The results indicate that the strength is declined with the increase of slit width. With the increase of thickness and concrete strength, the strength and stiffness are enhanced. The strength is larger with the boundary than without. Slit width and thickness have an important impact on the stiffness. Concrete strength and boundary conditions have little impact on stiffness. The strengthened nonductile RC frames have enough ductility.

We proposed a promising method for fabricating elliptical microlens and microlens array with controlling morphology by slit-based spatially shaped femtosecond laser-assisted chemical etching on fused silica (SiO2). The major axis length and the ratio of major and minor axis were controlled by changing the slit width. The minor axis length was controlled by changing the energy. This method had good flexibility and high efficiency. The convex elliptical microlens and microlens array were also realized by mold replication.

In this paper, investigation on fiber laser cutting of CFRP was carried out through establishing a multi-physical finite element model and cutting experiment. A multi-physical field model of laser cutting of CFRP was established. Experiments on 1 kW fiber laser cutting of 1 mm CFRP was performed. The relationship between cutting quality (slit width, notch taper, and HAZ width) and laser process parameters such as laser power and cutting speed was investigated. The results show that the transfer of laser energy in CFRP is mainly along the direction of fiber laying, and the heat transfer speed in carbon fiber is much faster than that in resin. The width of the slit, HAZ and the notch taper all increase with the increasing of laser power. However, the width of slit and HAZ decrease as the cutting speed increase and the notch taper increased first and then decreased. When the laser power is 150 W and the cutting speed is 1 m/min, the cutting quality is better.

Relative Response Factors (RRFs) can be used for quantitation of one compound against another and it is widely used for Impurity analysis of pharmaceutical products; however, the application in potency assay is limited. Through an extensive study shown in this paper, it can be concluded that using the “RRF methodology” for potency assay is much more challenging compared to impurity analysis, due to the much tighter criteria required for potency analysis. The effects of instrument settings, which are rarely discussed or recognized in current HPLC analytical method development and quality release testing, are discussed. These factors impact the RRF just as much as other commonly recognized HPLC parameters. The effects of UV detector settings, i.e. Slit Width, Step Width, Band Width, and Data Collection Module, have been explored. This phenomenon has been demonstrated using three compounds to observe the impact of their quantitation due to the significant RRF variations. Finally, principles to reduce RRF variations have been discussed, and practical considerations of RRF application to method development and method transfer are provided.

The luminosity of lightning channel is closely related to the lightning current. In the present paper, a lightning channel luminosity detection system (LCLDS), comprising of an avalanche photodiode module, a neutral density filter, an extension tube and an adjustable horizontal slit, is assembled. By using the impulse current generator, lightning impulse currents with different amplitudes and also different waveforms were produced in a 15-mm open-air gap between two graphite-rod electrodes. The luminosity and the current of discharge channel were measured synchronously. The experiments looking into the influencing factors of luminosity measurement, including the alignment of the silt and the slit width, were carried out. Obtained results show that the slit opening center of LCLDS should be aligned to the center of the discharge gap. Otherwise, in the case of improper alignment, the measured luminosity waveforms associated with the same injected current might be quite different in the amplitudes as well as in the waveforms. Moreover, the peak luminosity increases linearly with increasing slit width, whereas the luminosity waveforms are practically unaffected, implying that, in the practical application, the slit width can be adjusted to alter the luminosity signal output according to the actual need. Obtained results here can establish the foundation to develop the correlation between the current and the corresponding luminosity in the future.

We demonstrate that the interference pattern of the plasmonic and photonic modes can be controlled by changing the slit width of a square slit structure. Based on the analyses of the plasmonic and photonic modes of slits with different widths, we theoretically derived the expressions of wavefield generated by a square slit. A far-field scattered imaging system is utilized to collect the intensity distribution experimentally. Various interference patterns, including stripes, square-like lattice array, and diamond-like lattice array, have been observed by adjusting the slit widths. In addition, the results were validated by performing finite-difference time-domain simulations, which are consistent with the theoretical and experimental results.

Research on the factors affecting the characteristics of film slit irrigation has not received sufficient attention, although this is a wide-adopted irrigation technology. Infiltration modelling based on fewer factors deserves priority in the field studies. A laboratory theoretical study was conducted to investigate the simulated effects of SWMS-2D (simulating water movement through soil in two-dimensional) on soil moisture and cumulative infiltration of film slit irrigation. Error analyses indicated that SWMS-2D was suitable for infiltration simulation. Besides, SWMS-2D was applied to investigate the cumulative infiltration affected by soil texture, initial soil moisture, irrigation water depth, soil structure, opening ratio (ρ), and film slit width (d) and spacing. Results showed that for a certain soil, initial soil moisture and irrigation water depth had the poorest effects, whereas ρ and d had the strongest effects on cumulative infiltration among the 6 influencing factors. Furthermore, a sim...

The critical temperatures of bulk and confined atomic fluids are investigated using values of the vapour−liquid interfacial free energy of coexistence obtained from grand-canonical transition-matrix Monte Carlo simulations using a histogram reweighting technique. The temperature corresponding to zero interfacial free energy of coexistence is the estimated critical temperature for the system under investigation. Slit width of confined atomic fluid for this investigation is varied from 40 to 1 fluid particle diameter. The obtained critical temperatures have shown nonlinear monotonic trend with inverse of slit width. Moreover, five different linear regimes of critical temperature are observed in the studied range of slit width. Interestingly, in the slit width range of less than two fluid particle diameters, the critical temperature approaches two-dimensional value and remains approximately indifferent with a decrease in slit width up to one fluid particle diameter. This investigation also reveals th...

Time-gated Raman system has been assembled using a pulsed laser and high-resolution echelle spectrograph. Echelle spectrograph provides broad spectral band-pass of 0–8500 cm�1 in a single scan with a resolution of 1.75 cm�1 for 532 nm at an extremely small slit width of 10 μm. Advantages of gated mode detection over continuous-wave mode detection are improved signal-to-noise ratio, reduced background signal, and unwanted fluorescent emission. Feasibility of echelle spectrograph for Raman measurements has been tested for both conventional and standoff distance of 5 m with all the external illumination sources on. The echelle system provides high-quality Raman signals with an extremely low inherent bandwidth in solid and liquid samples, (~8 cm�1 ) for 478 cm�1 fundamental band of sulfur. Intensity ratio of e2 fundamental to a1 fundamental of conventional and remote Raman measurements indicates that the spectral features remain the same in both measurements. The advantages of ‘time-gated’ Raman compared with continuous-wave mode detection, like low background even under extraneous illumination and lowered fluorescence, are also illustrated with spectrum of sulfur taken in the two modes.

The visual control of pecking by pigeons (Columba livia) has latterly been thought to be restricted to the fixation stops interrupting their downward head movements because these stops prevent interference by motion blur. Pigeons were also assumed to close their eyes during the final head thrust of the peck. Here we re-examine their pecking motions using high-speed video recordings and supplementary provisions that permitted a three-dimensional spatial analysis of the movement, including measurements of their pupil diameters and eyelid slit width. The results confirm that pigeons do not close their eyes completely during the presumed optically ballistic phase of pecking. Instead their eyelids are narrowed to a slit. The width of this slit is sensitive to both the ambient illumination levels and the visual backgrounds against which seed targets have to be detected and grasped. There is also evidence of some interaction between pupil diameter and eyelid slit width. We surmise that besides being an eye-protecting reflex, the partial covering of the pupil with the eyelids may increase the depth of focus, enabling pigeons to obtain sharp retinal images of peck target items at very close range and during the beak-gape ‘handling’ of food items and occasional grit particles.

The present work deals with the broadening of rotational lines of the carbon monoxide 2–0 band by both argon and hydrogen chloride. A high resolution grating spectrometer with a spectral slit width of 0.07 cm(−1) was used, necessitating only a small correction in observed half-width values. Sufficiently small contributions of CO self-broadening were obtained by using long pathlength cells of 12 meters for CO-argon mixture and 1 meter for CO-HCl mixture. Half-width results, which are considered accurate to within ±5 percent, are presented in the form of a table and by a graph.

We study, in this paper, the physical properties of water confined between two parallel graphene plates with different slit widths to understand the effects of confinement on the water structure and how bulk properties are reached as the water layer thickens. It was found that the microscopic structures of the interfacial liquid layer close to graphene vary with the slit width. Water tends to locate at the center of the six-membered ring of graphene planes to form triangular patterns, as found by others. The narrower the slit width is, the more pronounced this pattern is, except for the slit width of 9.5 A, for which a well-defined two-layer structure of water forms. On the other hand, squared structures can be clearly seen in single snapshots at small (6.5 A and 7.5 A) but not large slit widths. Even at small slit widths, the square-like geometry is observed only when an average is taken for a short trajectory, and averaging over a long time yields a triangular pattern dictated by the graphene geometry. We estimate the length of time needed to observe two patterns, respectively. We also used the two-phase thermodynamic model to study the variation of entropy of confined water and found that at 8.5 A, the entropy of confined water is larger than that of bulk water. The rotational entropy of confined water is higher than that of bulk water for all slit widths due to the reduction of the hydrogen bond in the confined space.

In this paper, a three-dimensional numerical model of H-type finned tube heat exchangers has been built. In order to optimize its structure and improve its performance, Taguchi method is applied to investigate the influence of seven geometric parameters including slit width, row number, fin height, spanwise tube pitch, longitudinal tube pitch, fin thickness and fin pitch. Numerical simulations are performed on eighteen cases with different combinations of seven geometric parameters and the overall thermal–hydraulic performance and its characteristics of heat transfer and flow friction are discussed in detail. The results show that fin pitch and fin height play a significant role on the heat transfer characteristics while the flow friction characteristics are mainly affected by fin height, spanwise tube pitch and fin pitch. The intuitive analysis and analysis of variance show that fin pitch, fin height and fin thickness have much stronger influence on its overall thermal–hydraulic performance than the rest four parameters. Finally, the optimal parametric combination of the H-type finned tube is obtained with an improvement of overall thermal–hydraulic performance by 11.4–16% for Re in range from 9000 to 24,000.

Recently, Panuski and Mungan presented the results of their study of light diffraction from a variable-width single slit by observing and measuring the diffraction pattern on an observation screen placed at a fixed distance. In this way, the authors were able to demonstrate to students the important near-field effects for single-slit diffraction, which most often have been neglected in introductory courses. In this paper, we show that there exists very good agreement between observed data and theoretical calculations by plotting intensity from single slits using a method with Fresnel-Kirchhoff integrals (Fig. 1). In addition to these comparisons, and with the evaluation of the Fresnel numbers, we argue that Panuski and Mungan demonstrated not only the near-field Fresnel, but also the far-field Fraunhofer regimes as well as the transition between the two. Furthermore, with a greater increase in the slit width, the transition to the geometric regime can be demonstrated (Fig. 2).

We present analytical solutions for the principal maxima in multiple slit diffraction. By expanding the angular position of the principal maxima in orders of a / d where d is the distance between two adjacent slits and a is the width of each slit, we obtain the angular position of the principal maxima up to the twelfth order in a / d .

The Beijing Faint Object Spectrograph and Camera (BFOSC) is one of the most important instruments of the 2.16-m telescope of the Xinglong Observatory. Every year there are ~ 20 SCI-papers published based on the observational data of this telescope. In this work, we have systemically measured the total efficiency of the BFOSC of the 2.16-m reflector, based on the observations of two ESO flux standard stars. We have obtained the total efficiencies of the BFOSC instrument of different grisms with various slit widths in almost all ranges, and analysed the factors which effect the efficiency of telescope and spectrograph. For the astronomical observers, the result will be useful for them to select a suitable slit width, depending on their scientific goals and weather conditions during the observation; For the technicians, the result will help them systemically find out the real efficiency of telescope and spectrograph, and further to improve the total efficiency and observing capacity of the telescope technically., 13 pages, 11 figures, 4 tables, accepted for publication in RAA

We study the conformational behavior of spherical polyelectrolyte brushes in the presence of monovalent and trivalent counterions in a confined environment. The confinement is exerted by two parallel walls on the brushes. The enhancement of the confinement induces the extension of grafted chains. For the monovalent case, the increase of the charge fraction leads to extended brush conformation for different slit width (distance between two walls) but collapsed brush in the presence of trivalent counterions is observed. The confinement does not affect electrostatic correlation between trivalent counterions and charged monomers. However, it was found that narrow slit width contributes to stronger electrostatic correlation for the monovalent case. This is because more monovalent counterions are inside the brush at strong confinement, but almost all trivalent counterions are trapped into the brush independently of the slit width. The diffusion of counterions under the confinement is related to the electrostatic correlation. Our simulations also reveal that the brush thickness depends on the slit width nonlinearly.