Research on Explosion Characteristics of Sulfur Dust and Risk Control of the Explosion

AbstractAs dust explosion is a major risk factor threating the safety of sulfur production, evaluating and controlling the hazards of sulfur dust produced in the wet process are very important. Several characteristic parameters including minimum ignition temperature, minimum ignition energy, lower explosive limit, maximum explosion pressure, explosion index, limit oxygen concentration of sulfur dust were determined and investigated by the experimental device such as hot plate, Godbert-Greenwald furnace, Hartmann tube, 20L spherical container of explosive testing. The experimental results indicated the influence rules of particle size, water content and concentration on the explosion characteristics of sulfur dust. The results showed that sulfur dust could be lighted easily and had high explosibility. The explosion risk and strength of sulfur dust decreased with the increase of the particle size. The minimum ignition energy and the minimum ignition temperature increased as the water content increased. The maximum explosion pressure and the explosion index rose at first and went down latter as the dust concentration increases. Prevention and control measures of sulfur dust explosion, from two aspects of building control and process control, were proposed for production, storage and transportation process of sulfur produced in the wet process

Three-dimensional carbon foam nanocomposites for thermal energy storage

Nanocomposites consisting of paraffin/graphene nanoplatelets mix embedded in carbon foams via vacuum infiltration were fabricated with the aim of developing new phase change material (PCM) formulation with excellent shape stabilization, improved thermal conductivity and outstanding thermal reliability and structural stability. Physicochemical and thermal properties of the nanocomposites were evaluated using a suite of techniques such as scanning and transmission electron microscopy, X-ray diffraction, attenuated total reflection - Fourier transform infrared spectroscopy, nitrogen adsorption analyzer, differential scanning calorimetry, mechanical tester, Raman spectroscopy, thermal conductivity analyzer and thermogravimetric analyzer. The carbon foams exhibited good cyclic compressive behavior at a strain of up to 95% and kept part of their elastic properties after cyclic testing. Due to the robust mechanical integrity and layered meso-/macroporous morphology of these carbon foams, the nanocomposites are well equipped to cope with volume changes without leaking during thermal cycling. A 141% thermal conductivity enhancement observed for the carbon foam nanocomposite demonstrates the contributing role of the carbon foam in creating effective heat transfer through its conductive 3D network. The results have shown that proper chemical modification and subsequent carbonization of the low cost porous foams can lead to ultralight multifunctional materials with high mechanical and physical properties suitable for thermal energy storage applications

In situ fabrication of dendritic tin-based carbon nanostructures for hydrogen evolution reaction

In this work, dendritic tin-based carbon (Sn/C) nanostructures with four different morphologies were synthesized by a facile two-step carbonization and chemical vapor deposition method and were then evaluated for their performance in hydrogen evolution reaction. The Sn/C dendrites are approximately 0.5 – 4.5 µm in length, each having secondary branches in different directions. The four morphologies of the Sn/C dendrites namely nanoflowers (Sn_NCF1), nanospheres (Sn_NCF2), nanocubes (Sn_NCF3) and nanocuboids (Sn_NCF4), behave differently in their electrochemical performance, with Sn_NCF2 and Sn_NCF1 performing better. Sn_NCF2 demonstrates optimal HER performance compared to other Sn based samples with onset potential and overpotential of 100 and 260 mV, respectively. The higher electrochemical surface area observed in Sn_NCF2 was originated from the presence of more catalytic sites which contributed to the enhanced HER activity and better current density, against other Sn-based samples. In addition to the improved HER performance, Sn_NCF2 demonstrates excellent stability with less than 6% degradation of its initial current after operating for over 8 h in acidic media

Carbon nanotube reinforced nanocomposites for energy conversion and storage

CNT-reinforced foams comprised of three-dimensional (3D) interconnected macropores with uniform mesoporous walls were developed as multifunctional nanocomposites and tested for electrochemical energy conversion and storage. Multi-walled CNTs grown on the wall surface of the interconnected scaffold structure of carbon foams were found to improve the surface area and electrochemical properties of the nanocomposites. The lightweight CNT-reinforced nanocomposites not only exhibit high structural flexibility, but also possess enhanced electrocatalytic performance for HER at current density of 10 mA cm−2 with overpotentials of 240 mV. In addition, these nanocomposites can be used as flexible, electric double layer capacitor electrodes, and have achieved a specific capacitance of 776 F g−1, with excellent durability and stability after 1000 cycles

Differential roles of TGIF family genes in mammalian reproduction

<p>Abstract</p> <p>Background</p> <p>TG-interacting factors (TGIFs) belong to a family of TALE-homeodomain proteins including TGIF1, TGIF2 and TGIFLX/Y in human. Both TGIF1 and TGIF2 act as transcription factors repressing TGF-β signalling. Human <it>TGIFLX </it>and its orthologue, <it>Tex1 </it>in the mouse, are X-linked genes that are only expressed in the adult testis. <it>TGIF2 </it>arose from <it>TGIF1 </it>by duplication, whereas <it>TGIFLX </it>arose by retrotransposition to the X-chromosome. These genes have not been characterised in any non-eutherian mammals. We therefore studied the TGIF family in the tammar wallaby (a marsupial mammal) to investigate their roles in reproduction and how and when these genes may have evolved their functions and chromosomal locations.</p> <p>Results</p> <p>Both <it>TGIF1 </it>and <it>TGIF2 </it>were present in the tammar genome on autosomes but <it>TGIFLX </it>was absent. Tammar <it>TGIF1 </it>shared a similar expression pattern during embryogenesis, sexual differentiation and in adult tissues to that of <it>TGIF1 </it>in eutherian mammals, suggesting it has been functionally conserved. Tammar <it>TGIF2 </it>was ubiquitously expressed throughout early development as in the human and mouse, but in the adult, it was expressed only in the gonads and spleen, more like the expression pattern of human <it>TGIFLX </it>and mouse <it>Tex1</it>. Tammar <it>TGIF2 </it>mRNA was specifically detected in round and elongated spermatids. There was no mRNA detected in mature spermatozoa. TGIF2 protein was specifically located in the cytoplasm of spermatids, and in the residual body and the mid-piece of the mature sperm tail. These data suggest that tammar <it>TGIF2 </it>may participate in spermiogenesis, like <it>TGIFLX </it>does in eutherians. <it>TGIF2 </it>was detected for the first time in the ovary with mRNA produced in the granulosa and theca cells, suggesting it may also play a role in folliculogenesis.</p> <p>Conclusions</p> <p>The restricted and very similar expression of tammar <it>TGIF2 </it>to X-linked paralogues in eutherians suggests that the evolution of <it>TGIF1</it>, <it>TGIF2 </it>and <it>TGIFLX </it>in eutherians was accompanied by a change from ubiquitous to tissue-specific expression. The distribution and localization of TGIF2 in tammar adult gonads suggest that there has been an ultra-conserved function for the TGIF family in fertility and that <it>TGIF2 </it>already functioned in spermatogenesis and potentially folliculogenesis long before its retrotransposition to the X-chromosome of eutherian mammals. These results also provide further evidence that the eutherian X-chromosome has actively recruited sex and reproductive-related genes during mammalian evolution.</p

Ultralight three-dimensional, carbon-based nanocomposites for thermal energy storage

Polymer based nanocomposites consisting of elastic three-dimensional (3D) carbon foam (CF), paraffin wax and graphene nanoplatelets (GNPs) have been created and evaluated for thermal energy storage. The ultralight, highly porous (∼98.6% porosity), and flexible CFs with densities of 2.84–5.26 mg/cm3 have been used as the backbone skeleton to accommodate phase change wax and nanoscale thermal conductive enhancer, GNP. Low level of defects and the ordered sp2 configuration allow the resulting CFs to exhibit excellent cyclic compressive behavior at strains up to 95%, while retaining part of their elastic properties even after 100 cycles of testing. By dispersing the highly conductive GNP nanofillers in paraffin wax and infiltrating them into the flexible CFs, the resultant nanocomposites were observed to possess enhanced overall thermal conductivity up to 0.76 W/(m K), representing an impressive improvement of 226%, which is highly desirable for thermal engineering