Reduction of Cracks in Marble Appeared at Hydro-Abrasive Jet Cutting Using Taguchi Method

The appearance of cracks in brittle materials in general and in marble, in particular, is a problem in the hydro-abrasive jet cutting process. In this paper is presented a method to reduce the appearance of cracks when cutting with a hydro-abrasive jet of marble by using statistical analysis. The Taguchi method was used, establishing the main parameters that influence the process. Research design was based on performing experiments by modifying the parameters that influence the process. In this way, it has been shown that the stochastic effects resulting from the marble structure can be reduced. A careful study was made of the behavior of marble under the action of the hydro-abrasive jet, and of the behavior of the whole process in the processing of brittle materials. Results of experiments confirmed the hypothesis that statistical analysis is a procedure that can lead to a decrease in the number of cracks in processing. The measurement was performed with precise instruments and analyzed with recognized software and according to the results obtained, the reduction of the number of cracks is achieved through use of low pressure, a minimum stand-off distance and a small tube diameter. In this way, the paper presents a new and effective tool for optimizing the cutting with a hydro-abrasive jet of marble.

Research on Influencing Factors of Heavy Oil Emulsification

In tight heavy oil reservoirs, the formation of W/O emulsion will significantly increase the viscosity of the whole fluid-system. Meanwhile, the emulsion droplets tend to block the core pores, which will reduce the flow oil and water. In this paper, the terms of oil-water ratio, pH and other factors on heavy oil emulsification of tight sandstone in a block of Xinjiang were studied. Furthermore, in order to study the emulsification behavior in large and small pores, a large tube and a small tube are used to investigate how the hole apertures affect heavy oil emulsification. Finally, the demulsification time and dehydration rate were recorded, and the interfacial tension and viscosity were tested. The results show that heavy oil is easy to self-emulsify with water to form W/O emulsion, and it’s extremely stable. When the oil-water ratio is 3:7, the viscosity of the emulsions reaches 307 mPa·s, which is 38 times higher than that of crude oil. Acidic and alkaline conditions are benefit of demulsification and the stability of the emulsions is reduced. In small tube with higher interfacial tension, the demulsification time is shortened, and the stability of the emulsions is reduced.

Influence of Macroscopic Wall Structures on the Fluid Flow and Heat Transfer in Fixed Bed Reactors with Small Tube to Particle Diameter Ratio

Fixed bed reactors are widely used in the chemical, nuclear and process industry. Due to the solid particle arrangement and its resulting non-homogeneous radial void fraction distribution, the heat transfer of this reactor type is inhibited, especially for fixed bed reactors with a small tube to particle diameter ratio. This work shows that, based on three-dimensional particle-resolved discrete element method (DEM) computational fluid dynamics (CFD) simulations, it is possible to reduce the maldistribution of mono-dispersed spherical particles near the reactor wall by the use of macroscopic wall structures. As a result, the lateral convection is significantly increased leading to a better radial heat transfer. This is investigated for different macroscopic wall structures, different air flow rates (Reynolds number Re = 16 ...16,000) and a variation of tube to particle diameter ratios (2.8, 4.8, 6.8, 8.8). An increase of the radial velocity of up to 40%, a reduction of the thermal entry length of 66% and an overall heat transfer increase of up to 120% are found.

Cell layer-specific expression of the B-class MADS-box gene PhDEF drives petal tube or limb development in petunia flowers

Floral homeotic MADS-box transcription factors ensure the correct development of floral organs with all their mature features, i.e. organ shape, size, colour and cellular identity. Furthermore, all plant organs develop from clonally-independent cell layers, deriving from the meristematic epidermal (L1) and internal (L2 and L3) layers. How cells from these distinct layers acquire their floral identities and coordinate their growth to ensure reproducible organ development is unclear. Here we study the development of the Petunia x hybrida (petunia) corolla, which consists of five fused petals forming a tube and pigmented limbs. We present petunia flowers expressing the B-class MADS-box gene PhDEF in the epidermis or in the mesophyll of the petal only, that we called wico and star respectively. Strikingly, the wico flowers form a very small tube while their limbs are almost normal, and the star flowers form a normal tube but very reduced and unpigmented limbs. Therefore, the star and wico phenotypes indicate that in the petunia petal, the epidermis mainly drives limb growth and pigmentation while the mesophyll mainly drives tube growth. As a first step towards the identification of candidate genes involved in specification of petal layer identities and tube/limb development, we sequenced the star and wico whole petal transcriptome at three developmental stages. Among downregulated genes in star petals, we found the major regulator of anthocyanin biosynthesis ANTHOCYANIN 1 (AN1), and we showed that, in vitro, PhDEF directly binds to its terminator sequence, suggesting that it might regulate its expression. Altogether this study shows that layer-specific expression of PhDEF drives petunia tube or limb development in a highly modular fashion, which adds an extra layer of complexity to the petal development process.

Optimized Tapered Fiber Decorated by Ag Nanoparticles for Raman Measurement with High Sensitivity

A tapered fiber decorated by Ag nanoparticles is prepared as a surface-enhanced Raman scattering (SERS) substrate. There are two key parameters during the preparation process, the fiber cone angle and the density of decorated AgNPs on the fiber tip surface. Their theoretical analysis on the forming mechanism and the optimization process is studied in detail. The tapered fibers with angles from 0.5 to 30° are successfully prepared, with a chemical method in a small tube using a bending interface. AgNPs with different densities are decorated on the surface of the tapered fibers with an electrostatic adsorption method. The optimized tapered fiber SERS probe with an angle of 12° and AgNPs density of 26.67% provides the detection of Rhodamine 6G (R6G) with 10−10 mol/L.

A case of malignant glaucoma following insertion of Preserflo™ MicroShunt

Purpose: To describe a case of malignant glaucoma following insertion of a Preserflo™ MicroShunt in a patient with primary open angle glaucoma (POAG). Design: Case report. Case: A 46-year-old Caucasian man with medically uncontrolled POAG developed malignant glaucoma 1 day after an uncomplicated insertion of a mitomycin C (MMC) augmented Preserflo MicroShunt (PMS). Results: Initial medical treatment with aqueous suppressants and atropine 1% resulted in temporary resolution of the episode, although partial occlusion of the PMS with iris required a Nd:YAG laser iridotomy to open the inlet of the device. However, the malignant glaucoma recurred 6 days later. Temporary resolution was subsequently achieved with an Nd:YAG laser peripheral irido-zonulo-hyaloidotomy in combination with topical atropine, though a subsequent PMS revision was required due to bleb encapsulation. Unfortunately, the revision procedure was followed 2 days later, by a further recurrence of malignant glaucoma which was eventually resolved by left pars plana vitrectomy (PPV) in combination with clear lens extraction (CLE) and surgical irido-zonulo-hyaloidectomy. Subsequently, the eye remained stable, with a deep anterior chamber (AC), a partially functioning bleb, and an intraocular pressure (IOP) of 14 mmHg on one topical IOP-lowering agent, 8 months after the last procedure. Conclusions: The management of malignant glaucoma after PMS insertion and its subsequent clinical course is described. Apart from the propensity for a small tube such as the PMS to obstruct with iris when the AC is shallow, management is similar to other scenarios in which malignant glaucoma may develop.

An alternative way to measure total lung capacity: a pilot study

Total lung capacity is usually measured by a body plethysmograph or helium dilution methods. In this study an alternative approach to obtain total lung capacity of spontaneous breathing subjects is introduced. The device utilises an optoelectronic plethysmograph and a small tube, which measures mouth pressure and allows total lung capacity to be obtained, which differs less than 0.4 L from the total lung capacity of the body plethysmograph. The method shows potential to be a less burdensome method to estimate total lung capacity determination than the body plethysmograph.