Experimental Study on the Short-Term Uniaxial Creep Characteristics of Sandstone-Coal Composite Samples

In this investigation, the uniaxial short-term creep tests with multi-step loading were conducted on the sandstone-coal composite samples, and the characteristics of creep strength, creep deformation, acoustic emission (AE), and creep failure of composite samples were studied, respectively. The creep strength of the composite sample decreased with the stress-level duration, which was mainly determined by the coal and influenced by the interactions with the sandstone. The creep deformation and damage of sandstone weakened the deformation and damage accumulation within the coal, resulting in the larger strength for the composite sample compared with the pure coal sample. The axial creep strain of composite sample generally increased with the stress-level or the stress-level duration under same conditions. The AE characteristics of composite sample were related to the creep strain rate, the stress level, the stress level duration, and the local failure or fracture during creep loading. The micro or macro failure and fracture within the composite sample caused the rise in the axial creep strains and the frequency and intensity of AE signals, especially the macro failure and fracture. The creep failures of composite samples mainly occurred within the coal with the splitting ejection failure accompanied by the local shear failure, and no obvious failures were found within the sandstone. The coal in the composite sample became more broken with the stress-level duration.

Automated control of the production process of antifriction polymer materials

This paper presents a technique of controlling the process of oil filling of polymer and composite materials, which allows automated determination of volumetric heating of a polymer or composite sample for the purpose of drying. The differentiation of the obtained results, presented in graphical form, made it possible to quickly analyze the dynamics of temperature changes in the thickness of the material, the change of which determines the rates and time of impregnation to a certain depth of the body of the polymer or composite sample in figure 1. According to the developed methodology, studies of the impregnation of the oil filler of a mixture of M8-B motor oil and hexane were carried out. For each experiment, time dependences of the impregnation rate were obtained. Based on the work carried out, the optimal proportion of a mixture of hexane and engine oil and the most favourable temperature conditions were determined. At the end of the research, the assumption about the possibility of using this technique for the purpose of its industrial use in the technology of oil filling of antifriction products made of polymer and composite materials was confirmed.

Estimation of Microwave Absorption Properties of RGO-SiC-LLDPE Composites

The present work investigate the microwave absorption properties of reduced graphene oxide (RGO)-Silicon carbide (SiC)-Linear low-density polyethylene (LLDPE) composites prepared in different concentration of fillers(10, 20, 30, 40 wt. %) with LLDPE matrix. Synthesis of RGO is confirmed from XRD analysis and SiC is used as received from supplier. Complex permittivity of the composites is measured using Nicolson Ross method showing an increasing trend with increasing filler concentrations with maximum and for 40 wt. % composite sample. Based on transmission line theory and using measured value of complex permittivity, conductor backed single and double layer absorber is designed by thickness optimization. The calculated reflection loss (RLc) value of ~-71 dB at 11.23 GHz is observed for 40 wt. % composite sample of 7 mm thickness with -10 dB absorption bandwidth of 1.48 GHz and -20 dB bandwidth of 0.64 GHz.

SiO2 Nanoparticles Derived from Arundo Donax L. Ash Composite with TiO2 Semiconductor for Efficient Photocatalytic Dye Reduction

In this report, the biomass derived silicon dioxide (SiO2) nanoparticles composite with titanium dioxide (TiO2) semiconductors used as efficient photocatalyst for degradation of Rhodamine B (RhB) dye molecules under UV-visible light irradiation is proclaimed. At first SiO2 derived from Arundo donax L. ash and TiO2 synthesized using titanium (IV) isopropoxide by co-precipitation method and then their different compositions prepared by wet impregnation method were exampled to various optical and atomic level fundamental studies. The amorphous and crystalline nature of SiO2 and TiO2 ratify from XRD and here it is found that the crystalline nature decreased in their compositions as compared to TiO2. 293 nm UV photons harvesting SiO2 observed which could be due to more impurity states presence on surface is further accomplished red shift after composition with TiO2 lead to moving photons harvesting nature towards visible region. The band gap increases in SiO2/TiO2 composites as for TiO2 composition is rapport well with the aforementioned redshift value. Out of all samples the low recombination rate is procured in 50 wt% SiO2/50 wt% TiO2 composite sample. The separated ~ 100–200 nm sized TiO2 nanoparticle and aggregated tiny SiO2 nanoparticles availability in composite sample is authentically substantiated from electron microscopic studies. The presence of Si, O and Ti elements in composite samples probed by XPS. Following the fundamental studies, the photocatalytic degradation ability of the as-prepared samples has been scrutinized against the degradation of Rh B dye in which the pronounced photocatalytic degradation efficiency 93.7% is successfully achieved on 50 wt% SiO2/50 wt% TiO2 nanocomposite photocatalyst.

The Use of Froth Flotation for Selective Separation of Plastic Wastes from Soil

The Use of Froth Flotation for Selective Separation of Plastic Wastes from Soil Kofi Moro and Dorothy A. Dechie Abstract — In recycling of plastics, unless the goal is to form composites or materials having special properties, it is not advisable to mix plastics of different kinds because of the differences in their molecular weights and chain lengths. Hence, there is the need to separate these plastics when they are mixed before recycle can be done. This project investigated the selective separation of Polypropylene (PP), Polystyrene (PS) and Polyethylene terephthalate (PET) plastics out of soils using froth flotation. Pulverized samples were prepared from post-consumer plastic sources (PP, PS and PET) and soil and mixed uniformly to form a composite sample. The composite sample was subjected to froth flotation. Two tests were performed. A first test, where there was no addition of a depressant (tannic acid), and a second test, where there was addition of tannic acid to depress some of the plastics in order to selectively separate them. Recoveries from each test work indicated that, plastics are naturally hydrophobic and can be floated out of soils without modifying their surface properties. However, selective separations of the plastics were achieved when tannic acid was used to modify the surface properties of the plastic types.

First report of squash vein yellowing virus naturally infecting butternut squash (Cucurbita moschata) in Texas

Virus diseases are major constraints to the production of cucurbits in the Texas Lower Rio Grande Valley. In September 2020, a ~8.1 ha butternut squash (Cucurbita moschata) field in Hidalgo County, Texas, was observed with virus-like symptoms of vein yellowing, leaf curl, mosaic, and foliar chlorosis. The proportion of plants with virus-like symptoms in this field was estimated at 30% and seven samples (symptomatic = 5; non-symptomatic = 2) were collected randomly for virus diagnosis. Initially, equimolar mixtures of total nucleic acid extracts (Dellaporta et. al. 1983) from two symptomatic samples from this field and extracts from 12 additional symptomatic samples from six other fields across south and central Texas was used to generate one composite sample for diagnosis by high throughput sequencing (HTS). The TruSeq Stranded Total RNA with Ribo-Zero Plant Kit (Illumina) was used to construct cDNA library from the composite sample, which was then sequenced on the Illumina NextSeq 500 platform. More than 26 million single-end HTS reads (75 nt each) were obtained and their bioinformatic analyses (Al Rwahnih et al. 2018) revealed several virus-like contigs belonging to different species (data not shown). Among them, 6 contigs that ranged in length from 429 to 3,834 nt shared 96 to 100% identities with isolates of squash vein yellowing virus (SqVYV), genus Ipomovirus, family Potyviridae. To confirm the HTS results, total nucleic acid extracts from the cucurbit samples from all seven fields (n = 46) were used for cDNA synthesis with random hexamers and the PrimeScript 1st strand cDNA Synthesis Kit (Takara Bio). A 1-μL aliquot of cDNA was used in 12.5-μL PCR reaction volumes with PrimeSTAR GXL DNA Polymerase (Takara Bio) and two pairs of SqVYV-specific primers designed based on the HTS derived contigs. The primer pairs SqYVV-v4762: 5′-CTGGATTCTGCTGGAAGATCA & SqYVV-c5512: 5′-CCACCATTAAGGCCATCAAAC and SqYVV-v8478: 5′-TTTCTGGGCAAACAAACATGG & SqYVV-c9715: 5′-TTCAGCGACGTCAAGTGAG targeted ~0.75 kb and ~1.2 kb fragments of the cylindrical inclusion (CI) and the complete coat protein (CP) gene sequences of SqVYV, respectively. The expected DNA band sizes were obtained only from the five symptomatic butternut squash samples from the Hidalgo Co. field. Two amplicons per primer pair from two samples were cloned into pJET1.2/Blunt vector (Life Technologies) and bidirectionally Sanger sequenced, generating 753 nt partial CI specific sequences (MW584341-342) and 1,238 nt that encompassed the complete CP (MW584343-344) of SqVYV. In pairwise comparisons, the partial CI sequences shared 100% nt/aa identity with each other and 98-99% nt/aa identity with corresponding sequences of SqVYV isolate IL (KT721735). The CP cistron of TX isolates shared 100% nt/aa identity with each other and 90-98% nt (97-100% aa) identities with corresponding sequences of several SqVYV isolates in GenBank, with isolates IL (KT721735) and Florida (EU259611) being at the high and low spectrum of nt/aa identity values, respectively. This is the first report of SqVYV in Texas, naturally occurring in butternut squash. SqVYV was first discovered in Florida (Adkins et al. 2007) and subsequently reported from few other states in the U.S. (Adkins et al. 2013; Egel and Adkins 2007; Batuman et al. 2015), Puerto Rico (Acevedo et al. 2013), and locations around the world. The finding shows an expansion of the geographical range of SqVYV and adds to the repertoire of cucurbit-infecting viruses in Texas. Further studies are needed to determine the prevalence of SqVYV in Texas cucurbit fields and an assessment of their genetic diversity.

First report of Cucurbit chlorotic yellows virus infecting cantaloupe (Cucumis melo L.) in Texas

Texas is a major producer of cucurbits such as cantaloupe (Cucumis melo L.), but outbreaks of virus-like diseases often adversely affect yields. Little is known about the identity of the causal or associated viruses. During studies conducted in fall 2020 to explore the virome of cucurbit fields in Texas, a commercial cantaloupe field (~4.1 ha) in Cameron County was observed with virus-like symptoms of interveinal chlorotic mottle and foliar chlorosis and disease incidence was estimated at 100%. Virus-like symptoms including mosaic and leaf curl were also observed in six additional fields across five south and central Texas counties of Atascosa, Hidalgo, Fort Bend, Frio, and Wharton. Forty-six plants, which included 32 symptomatic and 14 non-symptomatic, were sampled from these fields for virus diagnosis and each sample was subjected to total nucleic acid extraction according to Dellaporta et. al. (1983). Initially, equal amounts of nucleic acids from 14 symptomatic plants (two/field) were pooled into one composite sample for preliminary diagnosis by high throughput sequencing (HTS). The cDNA library obtained from the composite sample with a TruSeq Stranded Total RNA with Ribo-Zero Plant Kit (Illumina) was sequenced on the Illumina NextSeq 500 platform, generating ~26.3 M single-end HTS reads (75 nucleotides [nt] each). Analyses of the reads according to Al Rwahnih et al. (2018) revealed several virus-like contigs; among them 23 contigs (206 to 741 nt) shared 98 to 100% nt identities to isolates of cucurbit chlorotic yellows virus (CCYV), genus Crinivirus, family Closteroviridae. Three pairs of CCYV-specific primers were designed from the HTS contigs with primers CCYV-v1330: 5′-AGTCCCTTACCCTGAGATGAA/CCYV-c2369: 5′-CGGAGCATTCGACAACTGAATA targeting ~1 kb fragment of the ORF1a (RNA1), primers CCYV-v4881: 5′-ATAAGGCGGCGACCTAATC/CCYV-c5736: 5′-GATCACTTGACCATCTCCTTCT targeting a ~0.9 kb fragment encompassing the coat protein (CP) cistron of CCYV (RNA2), and primers CCYV-v6362: 5′-CACCTCTTCCAGAACCAGTTAAA/CCYV-c7423: 5′-TGGGAACAACTTATTTCTCCTAGC targeting ~1 kb spanning partial minor coat protein (CPm) and p26 sequences (RNA2). Total nucleic acid extracts of each of the 46 samples from the seven fields were tested by two-step reverse transcription polymerase chain reaction using all three CCYV-specific primer pairs and they yielded amplicons of expected sizes from all five symptomatic cantaloupe samples from the Cameron County field and one additional symptomatic butternut squash sample from a field in Hidalgo County. The DNA bands from three randomly chosen cantaloupe samples were cloned and sequenced as previously described (Oke et al. 2020). In pairwise comparisons, the obtained 1,040 nt ORF1a (MW584332-334), 753 nt complete CP (MW584335-337), and 1,062 nt CPm/p26 (MW584338-340) gene specific sequences from the three samples shared 100% nt identity with each other, and 99-100% nt identities with corresponding RNA1 (AB523788) and RNA2 (AB523788) sequences of the exemplar isolate of CCYV. This is the first report of CCYV in Texas, thus expanding the current geographical range of the virus in the U.S. that includes California (Wintermantel et al. 2019) and Georgia (Kavalappara et al. 2021). The abundance of whiteflies of the Bemisia tabaci species complex in south Texas and other major U.S. cucurbit production areas presents additional challenges to virus disease management.