RESUMEN
Jet noise is a common problem in minimum quantity lubrication (MQL) technology. This should be given great attention because of its serious impacts on the physical and mental health of the operators. In this study, a micro-grooved nozzle is proposed based on the noise reduction concept of biological micro-grooves. The flow field and acoustic characteristics of an original nozzle and a micro-grooved nozzle were investigated numerically to help better understand the noise reduction mechanism. The reasons for noise generation and the effects of the length (L), width (W) and depth (δ) of the micro-grooves on noise reduction were analyzed. It was found that jet noise is generated by the large-scale vortex ring structure and the pressure fluctuations caused by its motion. The overall sound pressure level (OASPL) decreased with the increases in W and δ, and increased with the increase in L. Among of them, δ has the greatest effect on noise reduction. The maximum noise reduction achieved was 6.66 dB, as verified by the OASPL test. Finally, the noise reduction mechanism was discussed in terms of the flow field, vorticity and the frequency characteristics. Micro-grooves can enhance the mixing of airflow inside the nozzle and accelerate the process of large-scale vortices breaking into smaller-scale vortices. It also reduces the sound pressure level (SPL) of middle frequencies, as well as the SPL of high frequencies on specific angles.
RESUMEN
Steel slag, desulphurised ash, desulphurised gypsum and ultra-fine iron tailing sand are common industrial solid wastes with low utilisation rates. Herein, industrial solid wastes (steel slag, desulphurised gypsum and desulphurised ash) were used as the main raw materials to prepare a gelling material and ultra-fine tailing was used as an aggregate to prepare a new type of cementing filler for mine filling. The optimal composition of the cementing filler was 75% steel slag, 16.5% desulphurised gypsum, 8.75% desulphurised ash, 1:4 binders and tailing mass ration and 70% concentration. The compressive strength of the 28-day sample reached 1.24 MPa, meeting the mine-filling requirements, while that of the 90-day sample was 3.16 MPa. The microscopic analysis results showed that a small amount of C3A reacted with the sulphate in the desulphurised gypsum to form ettringite at the early stage of hydration after the steel slag was activated by the desulphurisation by-products. In addition, C2S produced hydrated calcium silicate gel in an alkaline environment. As hydration proceeded, the sulphite in the desulphurised ash was converted to provide sulphate for the later sustained reaction. Under the long-term joint action of alkali and sulphate, the reactive silica-oxygen tetrahedra and alumina-oxygen tetrahedra depolymerised and then polymerised, further promoting the hydration reaction to generate hydrated calcium silicate gel and ettringite. The low-carbon and low-cost filler studied in this paper represents a new methodology for the synergistic utilisation of multiple forms of solid waste.
RESUMEN
This work determined and analyzed the complete chloroplast genome sequence of Ceratopteris thalictroides (Linnaeus) Brongniart 1822 (Pteridaceae). The results indicate that the total chloroplast genome size of C. thalictroides is 149,399 bp in length, and the genome contains a large single-copy (LSC) region of 83,580 bp, a small single-copy (SSC) region of 21,241 bp, and a pair of inverted repeat (IR) regions of 22,289 bp. The GC content of C. thalictroides is 36.7%. The genome encodes a total of 131 unique genes, including 82 protein-coding genes, 38 tRNA genes, and 8 rRNA genes. The phylogenetic analysis results strongly suggest that C. thalictroides is closely related to C. cornuta.
RESUMEN
Understanding how natural hybridization and polyploidizations originate in plants requires identifying potential diploid ancestors. However, cryptic plant species are widespread, particularly in Ceratopteris (Pteridaceae). Identifying Ceratopteris cryptic species with different polyploidy levels is a challenge because Ceratopteris spp. exhibit high degrees of phenotypic plasticity. Here, two new cryptic species of Ceratopteris, Ceratopteris chunii and Ceratopteris chingii, are described and illustrated. Phylogenetic analyses reveal that each of the new species form a well-supported clade. C. chunii and C. chingii are similar to Ceratopteris gaudichaudii var. vulgaris and C. pteridoides, respectively, but distinct from their relatives in the stipe, basal pinna of the sterile leaf or subelliptic shape of the fertile leaf, as well as the spore surface. In addition, chromosome studies indicate that C. chunii and C. chingii are both diploid. These findings will help us further understand the origin of Ceratopteris polyploids in Asia.
RESUMEN
Isoetes hypsophila Hand.-Mazz. is an Endangered quillwort living in plateau wetlands in China. In the present study, the complete chloroplast genome of I. hypsophila was assembled. It is a circular form of 146,362 bp in length, comprising a pair of inverted repeat (IR) regions of 13,691 bp, a large single copy (LSC) of 91,741 bp, and a small single copy (SSC) of 27,239 bp. After annotation, a total of 135 genes were predicted, which are 84 encode proteins 37 tRNA and 8 rRNA. The phylogenetic analysis indicated that I. hypsophila clustered with a clade of I. sinensis, I. taiwanensis and I. yunguiensis with strong support value. The chloroplast genome will contribute to further research and conservation of I. hypsophila.
RESUMEN
OBJECTIVE: To investigate the clinical features in children with tuberous sclerosis complex (TSC)-associated cardiac rhabdomyomas (CRM). METHODS: The clinical data of 15 children with TSC complicated by CRM were collected. The clinical features of the patients were analyzed, and TSC gene mutations were detected. RESULTS: Eleven cases (73%) developed multiple CRM. The majority of the tumors were located in the left and right ventricles. Most tumors presented as a round-like hyperechogenic mass with a clear margin on echocardiography. Arrhythmias occurred in 3 patients and 2 patients experienced heart failure. Gene mutation tests were performed in 2 patients, and pathogenic mutations were detected in both patients, which were TSC1 mutation and TSC2 mutation, respectively. Three patients were followed up for 6 to 38 months, and their CRM shrank or regressed spontaneously. CONCLUSIONS: TSC-associated CRM is generally multiple. Heart failure and arrhythmias may occur in some patients. Echocardiography is important for diagnosis of CRM. TSC-associated CRM has an inclination to spontaneous regression. TSC can be diagnosed at a molecular genetic level by TSC gene mutation detection.