Comparative Characterization and Identification of Poly-3-Hydroxybutyrate Producing Bacteria with Subsequent Optimization of Polymer Yield

In this work, the strains Bacillus megaterium BM 1, Azotobacter chrocococcumAz 3, Bacillus araybhattay RA 5 were used as an effective producer of poly-3-hydroxybutyrate P(3HB). The purpose of the study was to isolate and obtain an effective producer of P(3HB) isolated from regional chestnut soils of northern Kazakhstan. This study demonstrates the possibility of combining the protective system of cells to physical stress as a way to optimize the synthesis of PHA by strains. Molecular identification of strains and amplification of the phbC gene, transmission electron microscope (TEM), extracted and dried PHB were subjected to Fourier infrared transmission spectroscopy (FTIR). The melting point of the isolated P(3HB) was determined. The optimal concentration of bean broth for the synthesis of P(3HB) for the modified type of Bacillus megaterium RAZ 3 was 20 g/L, at which the dry weight of cells was 25.7 g/L−1 and P(3HB) yield of 13.83 g/L−1, while the percentage yield of P(3HB) was 53.75%. The FTIR spectra of the extracted polymer showed noticeable peaks at long wavelengths. Based on a proof of concept, this study demonstrates encouraging results.

Characteristics of Particles and Debris Released after Implantoplasty: A Comparative Study

Titanium particles embedded on peri-implant tissues are associated with a variety of detrimental effects. Given that the characteristics of these detached fragments (size, concentration, etc.) dictate the potential cytotoxicity and biological repercussions exerted, it is of paramount importance to investigate the properties of these debris. This study compares the characteristics of particles released among different implant systems (Group A: Straumann, Group B: BioHorizons and Group C: Zimmer) during implantoplasty. A novel experimental system was utilized for measuring and collecting particles generated from implantoplasty. A scanning mobility particle sizer, aerodynamic particle sizer, nano micro-orifice uniform deposit impactor, and scanning electron microscope were used to collect and analyze the particles by size. The chemical composition of the particles was analyzed by highly sensitive microanalysis, microstructures by scanning electron microscope and the mechanical properties by nanoindentation equipment. Particles released by implantoplasty showed bimodal size distributions, with the majority of particles in the ultrafine size range (<100 nm) for all groups. Statistical analysis indicated a significant difference among all implant systems in terms of the particle number size distribution (p < 0.0001), with the highest concentration in Group B and lowest in Group C, in both fine and ultrafine modes. Significant differences among all groups (p < 0.0001) were also observed for the other two metrics, with the highest concentration of particle mass and surface area in Group B and lowest in Group C, in both fine and ultrafine modes. For coarse particles (>1 µm), no significant difference was detected among groups in terms of particle number or mass, but a significantly smaller surface area was found in Group A as compared to Group B (p = 0.02) and Group C (p = 0.005). The 1 first minute of procedures had a higher number concentration compared to the second and third minutes. SEM-EDS analysis showed different morphologies for various implant systems. These results can be explained by the differences in the chemical composition and microstructures of the different dental implants. Group B is softer than Groups A and C due to the laser treatment in the neck producing an increase of the grain size. The hardest implants were those of Group C due to the cold-strained titanium alloy, and consequently they displayed lower release than Groups A and B. Implantoplasty was associated with debris particle release, with the majority of particles at nanometric dimensions. BioHorizons implants released more particles compared to Straumann and Zimmer. Due to the widespread use of implantoplasty, it is of key importance to understand the characteristics of the generated debris. This is the first study to detect, quantify and analyze the debris/particles released from dental implants during implantoplasty including the full range of particle sizes, including both micro- and nano-scales.

First report of tomato fruit blotch virus infecting tomatoes in Brazil

Recently, a new blunervirus was reported in tomatoes showing fruit chlorotic lesions. This virus, named tomato fruit blotch virus (ToFBV), was found associated with the tomato fruit blotch disease in Italy and Australia, even though Koch’s postulates were not fulfilled and no viral particles were seen in leaf dips observed with an electron microscope (Ciuffo et al. 2020). In December 2019, symptoms of circular or irregular chlorotic blotches were observed in tomato fruits in an organic farm in Distrito Federal, Brazil. Five different tomato cultivars (2100 plants of cv. Sweet grape, 1700 of Giacomo, 560 of Grazianni, 160 of Tropical, and 160 of DRC 5640) were being grown in two greenhouses and all of them presented the symptoms in at least one fruit, particularly in older fruits. No virus-like symptoms were observed in young and middle leaves, but older leaves could not be examined because they were removed as a routine activity of the farm; and also due to the moderate infestation of the tomato russet mite Aculops lycopersici, associated with leaf and stem necrosis. No viral particles were observed in an electron microscope analysis of symptomatic fruit tissues, and sap inoculation and grafting of stems did not produce any symptom in indicator plants. Two young and asymptomatic plants with the first fruits still in development were removed from another greenhouse of the farm and transported to our greenhouse, but the typical blotch symptoms neither appeared in the fruits nor the necrosis symptoms in the leaves. Serological tests performed for all collected leaf and fruit samples using antibodies produced in-house against common tomato-infecting tospoviruses and potyviruses were negative, as well as a polymerase chain reaction (PCR) detection test for begomoviruses (Rojas et al. 1993). Total RNA from newly collected samples consisting of one symptomatic fruit sample and five asymptomatic leaf samples from distinct plants were individually extracted using RNeasy Plant Mini Kit (Qiagen, Hilden, Germany) and pooled for next generation sequencing (NGS). The library was constructed using TruSeq Stranded Total RNA with Ribo-Zero Plant (Illumina, San Diego, USA) and sequenced at Macrogen, Inc. (Seoul, South Korea) in an Illumina Novaseq6000 platform. The 4,621,977,958 reads obtained were trimmed using Trimommatic 0.35 (Bolger et al. 2014) and contigs were assembled using Velvet (Zerbino and Birney 2008). Following tblastx analysis on Geneious 9.1.8 (Biomatters Ltd.) and BLAST on the NCBI platform (Altschul et al. 1990), seven contigs matching tomato chlorosis virus (ToCV) and five contigs matching ToFBV were identified. Sequences for each of the four genome components of ToFBV (MK517477-MK517480) already present in databases were used as reference using the Map to Reference function in Geneious. A total of 338,402, 78,039, 555,302 and 461,474 reads mapped to virus genome components 1 to 4, respectively, with >99% coverage for each. Four final consensus sequences were used for BLAST analyses on NCBI and presented 97 to 99.7 % nucleotide identity with those used for mapping. These sequences were deposited in GenBank as isolate MAL under accession numbers MW546267 (RNA 1, 5770 nt), MW546268 (RNA 2, 3612 nt), MW546269 (RNA 3, 2826 nt) and MW546270 (RNA 4, 1950 nt). The primer pair Bluner1F (5’-ATTCCTGTTCCTTCGGATAAACTCGT-3’) and Bluner1R (5’-CACACGTGCAGGAAATGGAAAGA-3’) directed to RNA 1 was used to specifically detect the virus. Three leaf samples and two fruit samples, each from a different plant with typical symptoms, were tested positive for ToFBV and negative using ToCV-specific primers in RT-PCR (Dovas et al. 2002). This confirmed that although some plants pooled in the HTS library were infected with ToCV, the chlorotic blotch symptom was clearly associated with the presence of ToFBV. Furthermore, the ~0.5 kbp amplicon for ToFBV-specific primers from one randomly selected sample was sequenced with both primers and the resulting sequence shared 100% nt identity with the RNA 1 of ToFBV isolate Fondi2018 from Italy (MK517477). Then, the virus was detected in the tissue from the surface of another fruit, but not from its internal part, suggesting a superficial infection. The findings presented here are of high phytosanitary significance, given the strong symptoms associated with tomato fruit blotch disease and the identification of ToFBV in the tomato samples from Brazil.

Advancement in fabrication of carbon nanotube tip for atomic force microscope using multi-axis nanomanipulator in scanning electron microscope

We have constructed a new nanomanipulator (NM) in a field emission scanning electron microscope (FE-SEM) to fabricate carbon nanotube (CNT) tip to precisely adjust the length and attachment angle of CNT onto the mother atomic force microscope (AFM) tip. The new NM is composed of 2 modules, each of which has the degree of freedom of three-dimensional rectilinear motion x, y and z and one-dimensional rotational motion θ. The NM is mounted on the stage of a FE-SEM. With the system of 14 axes in total which includes 5 axes of FE-SEM and 9 axes of nano-actuators, it was possible to see CNT tip from both rear and side view about the mother tip. With the help of new NM, the attachment angle error could be reduced down to 0º as seen from both the side and the rear view, as well as, the length of the CNT could be adjusted with the precision using electron beam induced etching. For the proper attachment of CNT on the mother tip surface, the side of the mother tip was milled with focused ion beam. In addition, electron beam induced deposition was used to strengthen the adhesion between CNT and the mother tip. In order to check the structural integrity of fabricated CNT, transmission electron microscope image was taken which showed the fine cutting of CNT and the clean surface as well. Finally, the performance of the fabricated CNT tip was demonstrated by imaging 1-D grating and DNA samples with atomic force microscope in tapping mode.

Performance enhancement of Scanning Electron Microscope using a Deep Convolutional Neural Network

We report noise reduction and image enhancement in Scanning Electron Microscope (SEM) imaging while maintaining a Fast-Scan rate during imaging, using a Deep Convolutional Neural Network (D-CNN). SEM images of non-conducting samples without conducting coating always suffer from charging phenomenon, giving rise to SEM images with low contrast or anomalous contrast and permanent damage to the sample. One of the ways to avoid this effect is to use Fast-Scan mode, which suppresses the charging effect fairly well. Unfortunately, this also introduces noise and gives blurred images. The D-CNN has been used to predict relatively noise-free images as obtained from a Slow-Scan from a noisy, Fast-Scan image. The predicted images from D-CNN have the sharpness of images obtained from a Slow-Scan rate while reducing the charging effect due to images obtained from Fast-Scan rates. We show that using the present method, and it is possible to increase the scanning rate by a factor of about seven with an output of image quality comparable to that of the Slow-Scan mode. We present experimental results in support of the proposed method.

Supervised Learning in image enhance from electron microscopy inversion results

In Nondestructive testing there is a variety of applications in Material Science, where the specimen is imaged by an Electron Microscope and then by image inversion, informationis extracted for the material interior. This type of information might contain noise either by the imaging procedure or by the numerical part of the inversion. We present a method that can improve the interior density results of an inversed material from a series of Scanning Electron Microscope (SEM) images. For this method, the material density can contain some discontinuity, such as regions where it is dense and regions where there are voids.The proposed method directly stands on the Bayesian learning framework, adopting Gaussian Stochastic Processes (GSPs). Two test sample cases that contain some discontinuities in the density are tested. We also provide a comparison between two different GSP modelling approaches; one is a typical GSP and the other accounts for discontinuity, by introducing hyperparameters. The GSP method gives reconstructed data in reasonable agreement with the known original density distribution, giving confidence that the method can be applied to experimentally obtained SEM images.

Effect of Microstructure Evolution and Corrosion Behavior on Phase Transformation of Nanocrystalline SUS304 Prepared by Dry Ice Shot Peening

Microstructure and corrosion behavior of nanocrystalline SUS304 by dry ice shot peening has been investigated in detail in term of phase transformation. SUS304 as metastable austenitic stainless has excellent corrosion resistance and induced martensite by shot peening process. However, the SUS304 has quite low strength which is difficult to wear as metallic component. The dry ice shot peening process was carried out on SUS304 surface for one and three hours. The microstructure was observed by transmission electron microscope (TEM) and scanning electron microscope (SEM) equipped with electron back-scattered diffraction (EBSD). The phase transformation was analyzed by X-ray diffraction (XRD). The corrosion testing was carried out in 3.5% NaCl solution. The result indicated that the grain size of SUS304 surface was finer by deformation due to dry ice shot peened process. The hardness was improved properly by the increasing the shot peened time, and the corrosion resistance was increased. The XRD results showed that three hours shot peening process induced martensite phase of SUS304 by 15 m thickness. It can be summarized that the dry ice shot peening can be induced phase transformation due to high deformation on the SUS304 surface

High Temperature Degradation Mechanism of Concrete with Plastering Layer

At present, the research on the high temperature degradation of concrete usually focuses on only the degradation of concrete itself without considering the effect of the plastering layer. It is necessary to take into account the influence of the plastering layer on the high temperature degradation of concrete. With an increase in the water/cement ratio, the explosion of concrete disappeared. Although increasing the water/cement ratio can alleviate the cracking of concrete due to lower pressure, it leads to a decrease in the mechanical properties of concrete after heating. It is proved that besides the water/cement ratio, the apparent phenomena and mechanical properties of concrete at high temperature can be affected by the plastering layer. The plastering layer can relieve the high temperature cracking of concrete, and even inhibit the high temperature explosion of concrete with 0.30 water/cement ratio. By means of an XRD test, scanning electron microscope test and thermogravimetric analysis, it is found that the plastering layer can promote the rehydration of unhydrated cement particles of 0.30 water/cement ratio concrete at high temperature and then promote the mechanical properties of concrete at 400 °C. However, the plastering layer accelerated the thermal decomposition of C-S-H gel of concrete with a water/cement ratio of 0.40 at high temperature, and finally accelerate the decline of mechanical property of concrete. To conclude, the low water/cement ratio and plastering layer can delay the deterioration of concrete at high temperature.