Passive Control of Silane Diffusion for Gradient Application of Surface Properties

Liquid lithography represents a robust technique for fabricating three-dimensional (3D) microstructures on a two-dimensional template. Silanization of a surface is often a key step in the liquid lithography process and is used to alter the surface energy of the substrate and, consequently, the shape of the 3D microfeatures produced. In this work, we present a passive technique that allows for the generation of silane gradients along the length of a substrate. The technique relies on a secondary diffusion chamber with a single opening, leading to a directional introduction of silane to the substrate via passive diffusion. The secondary chamber geometry influences the deposited gradient, which is shown to be well captured by Monte Carlo simulations that incorporate the passive diffusion and grafting processes. The technique ultimately allows the user to generate a range of substrate wettabilities on a single chip, enhancing throughput for organ-on-a-chip applications by mimicking the spatial variability of tissue topographies present in vivo.

Carbon dioxide levels and ventilation in Acromyrmex nests: significance and evolution of architectural innovations in leaf-cutting ants

Leaf-cutting ant colonies largely differ in size, yet all consume O 2 and produce CO 2 in large amounts because of their underground fungus gardens. We have shown that in the Acromyrmex genus, three basic nest morphologies occur, and investigated the effects of architectural innovations on nest ventilation. We recognized (i) serial nests, similar to the ancestral type of the sister genus Trachymyrmex , with chambers excavated along a vertical tunnel connecting to the outside via a single opening, (ii) shallow nests, with one/few chambers extending shallowly with multiple connections to the outside, and (iii) thatched nests, with an above-ground fungus garden covered with plant material. Ventilation in shallow and thatched nests, but not in serial nests, occurred via wind-induced flows and thermal convection. CO 2 concentrations were below the values known to affect the respiration of the symbiotic fungus, indicating that shallow and thatched nests are not constrained by harmful CO 2 levels. Serial nests may be constrained depending on the soil CO 2 levels. We suggest that in Acromyrmex , selective pressures acting on temperature and humidity control led to nesting habits closer to or above the soil surface and to the evolution of architectural innovations that improved gas exchanges.

Experimental Study on the Spread Characteristics of Initial Fires According to Corridor Types

During an accidental fire in buildings, the corridor becomes the path for flame and smoke to spread, exposing the occupants to danger. Therefore, this study conducted real-scale fire experiments using corridors of size 2.4(L) × 10(W) × 2.4(H) m an “L-type” corridor for one-way evacuation and a “T-type” corridor for two-way evacuation to analyze the characteristics of fire according to the shape of corridors. The real-scale fire experiments were conducted in a fire room (2.4(L) × 3.6(W) × 2.4(H) m) with a single opening (2.0(W) × 1.8(H) m). The combustibles used inside the fire room were wood cribs, with a heat release rate of 651.4 kW, in the L-type corridor and chairs, with a heat release rate of 95.7 kW, in the T-type corridor. The temperature inside the corridor was measured during the real-scale fire experiments, and the average maximum measured temperature was 432.1 °C in the L-type corridor and 103.5 °C in the T-type corridor. The experimental results and the ventilation characteristics according to the corridor types were applied to BFD curves to show the process of designing fire growth models according to corridor types.

Optimization of Caving Technology in an Extrathick Seam with Longwall Top Coal Caving Mining

The optimization of top coal caving technology is an efficient method to improve the recovery ratio in longwall top coal caving (LTCC). In extrathick coal seams, the conventional single-opening sequential caving technology (SOSCT) shows the following problems: low recovery ratio, high rock mixed ratio, and poor drawing balance. For these problems, this research verifies the applicability of multiopening caving technology (MOCT) in extrathick coal seams theoretically. However, different drawing sequences have a great effect on the drawing mechanism. Based on the progressive drawing sequence of cluster-group-support, this paper firstly proposes a systematic naming method for the top coal caving technology. Furthermore, an independent cluster-group caving technology (ICGCT) is given, meaning that all supports are divided into several clusters, a cluster is divided into several groups, and clusters extract top coal in positive order while groups are in reverse order in the drawing process. By establishing an experimental model by the discrete element method PFC2D, the drawing mechanism is investigated under different caving technologies. The results show that ICGCT significantly improves the recovery ratio of the panel and mainly increases the drawing volume of top coal in the middle and upper end of the panel. The shape of the top coal boundary reflects the drawing efficiency. Due to the effect of drawing sequence in ICGCT, the generation and disappearance processes of coal ridge greatly decrease the residual top coal in the middle of the panel. The drawing body shape has a direct influence on the recovery ratio. Multiple complete drawing bodies exist in ICGCT, and the dispersion coefficient of drawing volume changes periodically in the range of 0.5–1.7, which is conducive to the management of drawing processes. In addition, discussing ICGCT and the dependent cluster-group caving technology (DCGCT), it is found that the recovery ratio of DCGCT has a slight increase, which enlarges the maximum drawing range of top coal at both panel ends, shortening the total drawing time of the panel. In summary, ICGCT provides a new approach for improving the recovery ratio and drawing balance in LTCC with an extrathick coal seam.

Oricymba gongshanensis sp. nov. (Cymbellaceae; Bacillariophyceae), a new species from southwest China

Oricymba gongshanensis sp. nov. is identified as a new cymbelloid species, and described from a rock wall in Gongshan County, Yunnan Province, China. A detailed morphological description of the new species is presented, based on light and scanning electron microscopy. O. gongshanensis sp. nov. has the features that assign it to the genus Oricymba, including a thickened ridge positioned around the margin of the valve, presence of pore fields at the apices, a stigma with a single opening externally and two openings internally together with external distal raphe ends deflected dorsally. There are three features that easily distinguish the new species from all others in the genus. They include: 1) valves that are weakly asymmetrical about the apical axis, 2) presence of mostly biseriate striae and 3) areolae that are round to elliptical in shape. Among the currently described species of Oricymba, the new species is most similar to O. tianmuensis in valve shape, but is easily distinguished by the degree of asymmetry about the apical axis and presence of biseriate striae. These findings increase our understanding the morphology and distribution of the genus Oricymba in China.

Mechanical and physical properties of boards made from recycled paper

Due to the increasing accumulation of wastes around the world, the demand for sustainable products is increasing. Paper is a commonly disposed of material that can pose problems even when it is recycled. The concept of using cardboard (CB) as a material for furniture production has been around for many years, but CB furniture does not last long. This study examined the feasibility of using post-consumer recycled paper to produce paper-based boards for furniture design. Cardboard (CB) and office paper (OP) were the main post-consumer materials that were used. The CB and OP were mixed with polylactic acid (PLA) and limestone. The boards were made at a temperature of 200 °C and pressed at a pressure of 3.5 N/mm2 using a single opening hydraulic press. The physical and mechanical properties were tested according to the European standards for wood-based panels. Tests that are critical for furniture parts, such as the modulus of rupture (MOR), the modulus of elasticity (MOE), the internal bond, the screw withdrawal resistance, the thickness swelling, and the water absorption were examined. The paperboard samples exceeded some of the requirements for the general use of boards for interior fitments (including furniture) for use in dry conditions (Type P2) and for non-load bearing boards for use in humid conditions (Type P3).

Anuran Heart Metamorphosis: Anatomical Support for Pulmonary Blood Separation in the Early Aquatic Phase

Background: In both larval and adult anurans, blood separation and respiratory physiology have remained an enigma. While various blood separation mechanisms have been proposed, the same structure is seen as playing a key role: the conus arteriosus. However, previous findings on its internal structure are contradictory, depending on the specifics of the 2D imaging methods used by different authors. To resolve this problem, we used high-resolution X-ray microtomography of whole Bufo bufo specimens to acquire the first detailed 3D descriptions of this complex structure through metamorphosis. Results: In early tadpoles two small valvular openings develop at the ventricular-conal junction, providing two paths separated by the septum coni and continuing into the aortic arches. Thus, structures to support segregated pulmonary circulation are fully developed well before the lungs appear. The external gills undergo partial resorption and retreat asymmetrically into a gill chamber formed by a hyoidal cover, leaving only a single opening on the left side, the opercular spout. Conclusions: The timing of events in Bufo circulatory development does not track the changing modes of respiration used by the developing tadpole. In particular, a system capable of double circulation carries only oxygen-depleted blood for a significant portion of the tadpole stage.