Small Rods Research Articles

Vortex shedding characteristics and hydrodynamic forces of stationary and elastically mounted side-by-side cylinders fitted with small diameter control rods

Vortex shedding behind bluff bodies can induce noise and vibration problems when it engages in a feedback cycle of oscillations with an acoustic or structural mode. Therefore, several passive and active flow control techniques have been developed to suppress vortex shedding behind a single bluff body. However, less attention was given to the case of multiple bluff bodies in cross-flow. Therefore, in this paper, a numerical investigation is performed to study the effect of adding small diameter control rods in the vicinity of two side-by-side cylinders on the vortex shedding characteristics, the hydrodynamic fluid forces, as well as the suppression of vortex-induced vibration. The simulations are conducted at a Reynolds number of Re = 200 and the side-by-side cylinders have a spacing ratio of T∗=2.5. The number of control rods and their angular positions around the main cylinders are varied. Fitting the side-by-side cylinders with control rods has resulted in three different flow regimes compared to the base case with no control rods. These flow regimes depend on the angular positions of the control rods and they are classified as; bistable flow, stable biased flow, and merged wake flow regimes. The stable biased flow regime has resulted in the maximum reduction of the fluctuating lift coefficient of the side-by-side cylinders, especially when the control rods are placed at θ=135° from the flow stagnation point. Increasing the number of control rods around the cylinders has further reduced the fluctuating lift coefficient and produced a more symmetric wake at the rod angles which produce the stable biased flow, and the merged wake flow regimes. The vortex-induced vibration of the side-by-side cylinders is investigated when the control rods are placed at the angular position that results in a stable biased flow regime. It is revealed that fitting the cylinders with control rods at an angular position of θ=135° has resulted in reducing the vibration amplitude over the whole range of the simulated reduced flow velocities, which makes this technique a viable one to control the vortex shedding and the vortex-induced vibration of side-by-side cylinders.

Design of Nanosecond-Level Transient Electric Field Sensor and Its Application in HVDC Converter Station

In this paper, a nanosecond-level transient electric field (E-field) sensor based on a monopole electrically small rod antenna is proposed. The working principle and design process of the sensor are analyzed in detail while a finite element simulation is carried out to verify the response characteristics of the sensor both in time and frequency domain, whose upper cut-off frequency can reach 680 MHz. For the purpose of assessing the actual detection capability of the sensor in HVDC converter stations, the sensor designed in this paper was used to detect the transient radiation E-field in the valve hall during the artificial short-circuit test in the Zhoushan 1200 kV five-terminal flexible DC transmission project. The measurement results of the transient E-field indicates that the sensor is able to respond instantaneously to the radiated E-field generated by the operation of the key power electronic equipment in the valve hall. It demonstrates that the designed sensor can be effectively applied in the scenario of the measurement of transient electromagnetic environment and non-invasive situational awareness technology for high-voltage devices in HVDC systems.

Influence of Immersed Conductive Objects on Quasi-Steady Burning Behavior of Fuel Slick in Turbulent Waters

ABSTRACT In situ burning (ISB) is an effective technique for burning oil spills that occur in oceans. The need for enhancing the burning characteristics and advancing the technique of burning fuels on the water sublayer has been identified. Following this, the study analyzes the steady burning behavior of a fuel layer floating on a turbulent water surface. The turbulent water surface is generated using an experimental platform comprising an axisymmetric upward-pointing submerged jet, an approach used in studies of free-surface turbulence. The turbulence is isotropic in the horizontal plane and bulk-flow free, with a turbulence intensity equal to 1.7 cm/s comparable to water turbulence in a calm ocean. The turbulent boundary condition causes an increase in heat extraction from the bottom of the fuel layer, thereby reducing the mass burning rate by 45% compared to a case with no turbulence. To improve the burning under turbulent water sublayer condition, a 10 mm conductive object is immersed at different depths in the fuel. The copper rod collects the flame’s heat and transmits it into the fuel layer via conduction, thereby increasing the burning rate by more than 1.4 times. A heat transfer model shows that the case with a small rod immersion depth (~10 mm) in a 40 mm fuel layer is best at improving burning because the heat losses from the object to the water sublayer are the lowest. The model also shows that the heat from the flame transmitted by the rod is primarily distributed in a region close to the surface of the fuel, where nucleate boiling is observed around the rod surface. As more of the rod is immersed in the fuel layer, the heat dissipation to the turbulent water increases nearly five times, thereby reducing the bubbling around the rod surface and the burning rate. The implications of burning fuel slicks for fast, slick cleanup during in-situ burning in turbulent water conditions are espoused.

Tractidigestivibacter montrealensis sp. nov., a new member of human gut microbiota isolated from a healthy volunteer.

Strain KD21T, isolated from the fecal sample of a healthy female volunteer, is a strictly anaerobic, non-motile, Gram-staining-positive, saccharolytic small rod that does not produce spores. Strain KD21T was able to grow in the range of temperature 28°C-37°C (optimum, 37 °C), pH 6.0-8.0 (optimum, pH 7.0), and with 0-5.0 g/l NaCl (optimum, 0g/l NaCl). Bacteria cells reduced nitrates to nitrites. Its major fatty acids were C18:1ω9c, C16:0, C18:0, and summed in feature 8 (C18:1ω7c and/or C18:1ω6c). 16S rRNA gene phylogenetic analysis revealed that KD21T is a member of the genus Tractidigestivibacter and is distinct from any species with validly published names. The sequence showed 98.48% similarity with T. scatoligenes SK9K4T. The DNA G+C content of strain KD21T was 62.6 mol%. The DNA-DNA hybridization and OrthoANI values between strain KD21T and T. scatoligenes SK9K4T were 40.2% and 90.2%, respectively. Differences in phenotypic, phylogenetic, chemotaxonomic, and genomic characteristics indicated that strain KD21T represents a novel species within the genus Tractidigestivibacter. The name T. montrealensis sp. nov. is proposed and the type strain is KD21T (= CSUR Q8103T = DSM 115111T).

Distribution, Size-Morphological Structure and Production of Heterotrophic Bacterioplankton in Gorky Reservoir

The abundance, biomass, size-morphological structure, growth rate and production of bacterioplankton, the intensity of primary phytoplankton production and dark fixation of CO2, as well as the abundance and biomass of heterotrophic nanoflagellates were determined in a large plain eutrophic reservoir (Gorky Reservoir, Middle Volga). The abundance, biomass, and production of bacterioplankton were relatively high and averaged 7.6 × 106 cells/mL, 117.9 mg C/m3, and 59.2 mg C/(m3 × day), respectively. Heterotrophic nanoflagellates reached a high level of quantitative development – 6.9 × 103 cells/mL, 47.9 mg C/m3. Their biomass averaged 41.6 ± 18.4% of the bacterioplankton biomass, which indicates that, in addition to bacteria, nanoflagellates used other food sources. Small rods and cocci dominated among the size-morphological bacterioplankton groups and accounted for 36.3 and 33.3% of its total abundance, respectively. Small rods averaged more than a half (56.2%) of the total biomass and were the most stable component of the community. The growth rate and production of bacterioplankton increased in those parts of the reservoir where the medium-sized cocci and coccobacilli accounted for from 18.2 to 29.3% of the total abundance. The highest bacterial activity was recorded in the area affected by the warm waste waters of the Volgorechensk State District Power Plant. Based on the data obtained, the reservoir divided on the upper river section and the lower lake section.

State of Cyanobacteria <i>Arthrospira platensis</i> and of Associated Microflora during Long-Term Storage in the State of Anhydrobiosis

Abstract—The biochemical composition of Arthrospira (Spirulina) platensis (Nordstedt) Gomont after long-term storage in the state of anhydrobiosis (4 years, 17 years) was determined by the standard methods. It was shown that protein content (55.3–61.2%) and total carbohydrates content (13.0–15.6%) in cyanobacterial cells were in agreement with the data known from the literature and with our results obtained at the onset of storage. The biomass had low content of free nucleotides (1.8–2.6%), lipids (1.3–11.0%), and especially pigments (0.5–1.3, 0.03–0.12, 1.4–2.0, 0.03–0.05% for chlorophyll a, carotenoids, C-phycocyanin, and allophycocyanin, respectively). The content of nucleic acids content was 3.1–24.0 and 0.11–0.16% for RNA and DNA, respectively. Microscopic examination of A. platensis (17 years of storage) showed high numbers of irreversibly damaged and dead cells (34.2 and 65.8%, respectively). To determine the quantitative and morphological parameters of associated microflora, a complex physicochemical treatment (methanol, ultrasound, and centrifugation) of the reactivated cyanobacterial suspension proved the most efficient. Three main groups were distinguished in the morphological structure of the microbiome (rod-shaped, rounded, and convoluted forms). The community was dominated by rod-shaped forms: large and small rods accounted for 60.5 and 14.4%, respectively. Mycelial forms (thin filaments), cocci, and convoluted forms were less common. On average, the volume of a bacterial cell was 0.27 ± 0.04 µm3. The contribution of bacteria to the biomass of A. platensis varied from 3.3 to 11.3% (8.3 ± 4.4% on average) of the dry weight of A. platensis. It has been suggested that the biochemical parameters and viability of cyanobacteria were affected by the accompanying microflora.

The first cultivated representatives of the actinobacterial lineage OPB41 isolated from subsurface environments constitute a novel order Anaerosomatales.

The continental subsurface harbors microbial populations highly enriched in uncultured taxa. OPB41 is an uncultured order-level phylogenetic lineage within the actinobacterial class Coriobacteriia. OPB41 bacteria have a wide geographical distribution, but the physiology and metabolic traits of this cosmopolitan group remain elusive. From two contrasting subsurface environments, a terrestrial mud volcano and a deep subsurface aquifer, located in the central part of Eurasia, within the Caucasus petroleum region, we have isolated two pure cultures of anaerobic actinobacteria belonging to OPB41. The cells of both strains are small non-motile rods forming numerous pili-like appendages. Strain M08DHBT is mesophilic, while strain Es71-Z0120T is a true thermophile having a broad temperature range for growth (25-77°C). Strain M08DHBT anaerobically reduces sulfur compounds and utilizes an aromatic compound 3,4-dihydroxybenzoic acid. Strain Es71-Z0120T is an obligate dissimilatory Fe(III) reducer that is unable to utilize aromatic compounds. Both isolates grow lithotrophically and consume molecular hydrogen or formate using either thiosulfate, elemental sulfur, or Fe(III) as an electron acceptor. Genomes of the strains encode the putative reductive glycine pathway for autotrophic CO2 fixation, Ni-Fe hydrogenases, putative thiosulfate/polysulfide reductases, and multiheme c-type cytochromes presumably involved in dissimilatory Fe(III) reduction. We propose to assign the isolated strains to the novel taxa of the species-order levels and describe strain M08DHBT as Anaerosoma tenue gen. nov., sp. nov., and strain Es71-Z0120T as Parvivirga hydrogeniphila gen. nov., sp. nov., being members of Anaerosomatales ord. nov. This work expands the knowledge of the diversity, metabolic functions, and ecological role of the phylum Actinomycetota.

Leidenfrost instability in a circular container and its suppression using a rod

Leidenfrost drops have demonstrated promising applications in, for example, drag reduction. However, large Leidenfrost drops may be unstable when their diameters exceed a critical value, leading to less control of such drops in their applications. In this work, through theoretical and experimental investigations, the authors explore the instability of a Leidenfrost drop in a circular configuration, as well as the suppression of this instability using a small rod. There are four findings. First, the diameter of the largest inscribed cylinder inside a rod–container configuration is the critical dimension for determining Leidenfrost instability. Second, in the cases of water and isopropyl alcohol, the threshold value of this diameter is 8.3λ ± 0.3λ, where λ is the capillary length of the liquid. Third, due to the specific interface profile between the liquid drop and the surrounding vapor layer, the threshold diameter of a circular container for instability to occur is slightly larger than its counterpart in the corresponding Rayleigh–Taylor instability problem. Fourth and finally, placing a rod inside a circular container reduces the size of the largest inscribed cylinder in the container. If the diameter of this inscribed cylinder is below the threshold value, the instability inside the container is suppressed.

TEM Study of the Microstructure of an Alumina/Al Composite Prepared by Gas-Pressure Infiltration.

Ceramic injection moulding and gas-pressure infiltration were employed for the manufacturing of alumina/AlSi10Mg composites. Porous ceramic preforms were prepared by mixing alumina powder with a multi-binder system and injection moulding the powder polymer slurry. Then, the organic part was removed through a combination of solvent and thermal debinding, and, finally, the materials were sintered at different temperatures. Degrading the binder enabled open canals to form. The sintering process created a porous ceramic material consisting of alumina without any residual carbon content. During infiltration, the liquid metal filled the empty spaces (pores) effectively and formed a three-dimensional network of metal in the ceramic. The microstructure and properties of the manufactured materials were examined using high-resolution transmission electron microscopy, porosimetry, and bending strength testing. Microscopy observations showed that the fabricated composite materials are characterised by a percolation type of microstructure and a lack of unfilled pores. The research confirmed the diversified nature of the connection at the particle–matrix interface. It was observed that the interphase boundary was characterised by the lack of a transition zone between the components or a continuous transition zone, with the thickness not exceeding 30 nm. Thanks to their increased mechanical properties and low density, the obtained composites could be used in the automotive industry as a material for small piston rings and rods, connecting rods, or even gears.

Modelling and gas–solid mixing characterization in the jiggled bed reactor (JBR)

AbstractThe jiggled bed reactor (JBR) is a new multiphase laboratory‐scale microreactor consisting of a sealed container attached to a piston that is rapidly moved up and down by a pneumatically powered actuator. Particles and fluids in the container are mixed by this up and down motion instead of mechanical agitators or a fluidizing gas. This alternating motion provides intense mixing of all phases (gas, liquid, or solid) and intense contact between phases. Small rods inside the solids bed are heated by induction, allowing for excellent control of bed temperature and heating rate. The JBR is inexpensive and easy to operate, and it has been applied to catalytic gasification of bio‐oil, biomass pyrolysis, activated carbon production, high‐pressure oil hydrogenation, and hydrocarbons adsorption. Experiments demonstrated that solids mixing depends on the reactor platform maximum accelerations during both up and down strokes. A minimum acceleration, 55 m2/s for the tested JBR, was required to achieve good solids mixing. A physical model was developed to predict the reactor platform motion and its maximum acceleration. It requires a few preliminary experiments (around 10) to obtain its four empirical parameters. The model can then determine how to adjust the actuator compressed air pressure or modify the equipment to eliminate performance bottlenecks.

ORAL TUBERCULOSIS: A CASE REPORT

Oral tuberculosis (TB) manifestations are uncommon and usually secondary to pulmonary changes. A 41-year-old male patient presented with the chief complaint of a painful ulcer on tip of his tongue. He reported that the ulcer developed without any remarkable event such as mechanical trauma, vesicle formation, or systemic illness. There was history of cough, fever, and chest pain. Chest x-ray and samples of acid-fast bacilli were positive. A biopsy was performed, and histological finding showed typical findings of oral TB including intense granulomatous inflammatory features with small red rods of mycobacterial organisms as well as epithelioid cells and Langerhans giant cells. After suitable antituberculosis treatments, the oral TB ulcer was almost completely healed after 1 year. We present a case of oral TB affecting the tip of the tongue in a patient with pulmonary TB and emphasize the understanding of intraoral manifestations for early diagnosis and prompt treatment of TB. Oral tuberculosis (TB) manifestations are uncommon and usually secondary to pulmonary changes. A 41-year-old male patient presented with the chief complaint of a painful ulcer on tip of his tongue. He reported that the ulcer developed without any remarkable event such as mechanical trauma, vesicle formation, or systemic illness. There was history of cough, fever, and chest pain. Chest x-ray and samples of acid-fast bacilli were positive. A biopsy was performed, and histological finding showed typical findings of oral TB including intense granulomatous inflammatory features with small red rods of mycobacterial organisms as well as epithelioid cells and Langerhans giant cells. After suitable antituberculosis treatments, the oral TB ulcer was almost completely healed after 1 year. We present a case of oral TB affecting the tip of the tongue in a patient with pulmonary TB and emphasize the understanding of intraoral manifestations for early diagnosis and prompt treatment of TB.

Formation of actin–cofilin rods by depletion forces

Various stress conditions induce the formation of actin–cofilin rods in either the nucleus or the cytoplasm, although the mechanism of rod formation is unclear. In this study, we constituted actin–cofilin rods using purified actin, cofilin and actin interacting protein 1 (AIP1) in the presence of a physiological buffer containing a crowding agent, 0.8% methylcellulose (MC), which led to bundled actin filaments formed by depletion forces. Most of the F-actin bundles formed with methylcellulose were linear, whereas cofilin-bound F-actin bundles often had bent, looped, and often ring-like shapes. Increasing the amount of AIP1 shortened actin–cofilin bundles into rod-like bundles with tapering at both ends. As much shorter actin–cofilin filaments were formed in the presence of AIP1 before MC was added to the mixture, the rod-like bundle might be a mass of those short filaments. Furthermore, the small rods fused with each other to become larger rods, indicating that these rods were anisotropic liquid droplets. Several minutes after the addition of MC to the F-actin–cofilin–AIP1 mixture, we observed some long bundles in which the thick and thin parts appear alternately, reminiscent of a Plateau–Rayleigh instability observed in fluid columns. Simultaneously, we found images in which thin parts were interrupted, but the thick parts were arranged in a row in the longitudinal direction. These structures were also observed in cytoplasmic actin–cofilin rods in cells overexpressing cofilin–GFP, suggesting that cytoplasmic actin–cofilin rods have the same structure formation process as the rods reconstituted in vitro.

Failure Transition and Validity of Brazilian Disc Test under Different Loading Configurations: A Numerical Study

The Brazilian disc test is a popular tensile strength test method for engineering materials. The fracture behavior of specimens in the Brazilian disc test is closely related to the validity of the test results. In this paper, the fracture process of granite discs under different loading configurations is simulated by using a coupled finite–discrete element method. The results show that the maximum tensile stress value is located within 18 mm (0.7 times the disc radius) of the vertical range of the disc center under different loading configurations. In small diameter rods loading, the invalid tensile strength is obtained because the crack initiation and plastic strain is at the end of the disc. The crack initiation points of flat platen loading and curved jaws loading are all within the center of the disc, and the valid tensile strength can be obtained. The tensile strength test results under different loading configurations show that the error of small diameter rods loading is 13%, while the errors of flat platen loading and curved jaws loading are both 1%. The curved jaws loading is the most suitable for measuring the tensile strength of brittle materials such as rock, followed by flat platen loading. The small diameter rods loading is not recommended for the Brazilian test.

Optimization of hexagonal boron-doped silicate photonic crystal fiber to obtain near zero flattened dispersion for nonlinear waves by finite difference method

The B2O3-doped silicate photonic crystal fiber (PCF) containing small core and dielectric rods built of lead silicate SF57 has been most intensively explored for diverse pump signals centered at a 0.65 µm, communication band. This type of doping has been carried out to diminish the upgraded refractive index of silica by a significant amount. This enhances special capabilities that lead to an outstanding potential to PCF for the profoundly intense field in the optical Kerr effect. In this study, the mode analysis has been done by solving a nonlinear wave equation for a Gaussian input beam using the finite difference method under analytical boundary conditions. Numerical results show that due to ultra-low changes in nonlinear behaviour, extremely small doping of B2O3 is needed to enable sustained confinement of a beam with flattened dispersion.

Observations on the cytomorphology and ultrastructure of the peripheral blood cells of native cattle (Zobawng) of Mizoram, India.

This study aims to characterize the cytomorphology and ultrastructure of blood cells of native cattle of Mizoram. Twelve numbers of blood samples (10ml) were collected from the Zobawng cattle, irrespective of sex. Blood smears were prepared and stained with different stains for cytomorphological study. The standard protocol has been followed for preparing blood samples for electron microscopy. Under a light microscope, erythrocytes of cattle were non-nucleated and round. The neutrophils were round, and the cytoplasm contained cytoplasmic granules. The eosinophils were rounded in outline with distinct cytoplasmic granules. The presence of basophils was infrequent with distinct blue color cytoplasmic granules. Small, medium, and large types of lymphocytes were recorded. The monocytes were round to oval in outline. Platelets were irregular to round. The reticulocytes were recorded occasionally, like small blue thin rods or granules. The cytoplasm and nucleus of granulocytes fluoresced greenish-yellow and red, respectively, with supravital stain. Under scanning electron microscopy (SEM), the erythrocytes appeared as biconcave discs. Different leukocytes were observed with their finger-like, plate-like, and narrow cell processes on their surface. Platelets were irregular structures. In transmission electron microscopy (TEM), the erythrocytes appeared anucleated biconcave elongated, neutrophils were roughly rounded with small cytoplasmic processes, and eosinophils were roughly circular with small cytoplasmic processes, the basophils were roughly circular with oval to elongated cytoplasmic granules, lymphocytes were roughly circular with centrally placed well-marked oval indented nucleus and some cytoplasmic processes, monocytes appeared spherical with long thick cytoplasmic processes and the non-nucleated platelets appeared roughly round to elongated. RESEARCH HIGHLIGHTS: Blood tests are a very good tool for determining animal health and diagnosing hematological illnesses. This study showed the cytomorphological and ultrastructural features of the blood cells of native cattle (Zobawng) of Mizoram state of India. The cytomorphological studies revealed that the morphological features of the blood cells of Zobawng cattle resembled to other domestic and wild animals, however, there were some differences in the cellular components. Nuclear DNA appeared orthochromatically greenish-yellow, but cytoplasmic RNA was observed to be metachromatically red under the fluorescence microscope. scanning electron microscopic (SEM) and transmission electron microscopic (TEM) results revealed that the ultrastructural features of the blood cells of Zobawng cattle contain certain cellular morphological differences as compared to the other domestic and wild animals.

Review on Listeriosis in small ruminants and public health significance in Ethiopia

Listeria monocytogenes is a bacterium mostly transmitted to man through food and it can cause mild gastroenteritis or severe infections of the bloodstream and/or the central nervous system, or abortion, depending on host susceptibility. Listeriosis is a serious illness caused by eating food contaminated with the bacterium Listeria, which is a Gram-positive psychotropic, facultatively anaerobic, none sporulating, motile, small rod. It displays characteristic tumbling motility that is facilitated by the presence of peritrichous flagella. Motility is temperature-dependent, showing high motility at 20-30°C when the flagellar expression is maximum. L. monocytogenes is ubiquitous in the environment and can be found in soil, water, feces, silage, effluent foods, and sewage. It has the ability to form biofilms which can contribute to its ability to colonize food processing facilities. The primary mode of transmission for Listeria is through soil contamination and ingestion of contaminated feed. Calves that develop the septicemic disease may acquire infection from contamination of the cow teat from the ingestion of milk containing the organism or from a cow with subclinical bacteremia, through the navel from the environment and also as congenital infection. Infection with Listeria. monocytogenes usually follow ingestion of contaminated feed and may result in septicemia, encephalitis, and abortion. There are few clinical features that are unique to listeriosis. Therefore, clinicians must consider a variety of potential causes of infection, including viral infections (influenza) and other bacterial infections that may cause sepsis or meningitis. Cook thoroughly raw food from animal sources, such as beef, pork, or poultry. Wash raw vegetables thoroughly before eating. Keep uncooked meats separate from vegetables and from cooked foods and ready-to-eat foods. Avoid raw (unpasteurized) milk or foods made from raw milk. Wash hands, knives, and cutting board and can contact with before and after handling cooked foods.

Demonstration of power distribution estimation using ex-core detectors by reactor experiment at UTR-KINKI

ABSTRACT A novel core power distribution reconstruction method based on ex-core detectors is demonstrated at the Kindai University Reactor UTR-KINKI. Technology to monitor the interior of the core is critical for assuring nuclear safety. Typical core monitoring systems utilize in-core detectors. However, the harsh environment inside the core degrades detector maintainability and reliability. On the other hand, monitoring using ex-core detectors is difficult due to the lack of information of neutrons. A previous study, therefore, proposed a new power distribution reconstruction method using power correlation between fuel regions, PHOEBE. However, PHOEBE has not been verified experimentally. Thus, the present study demonstrates PHOEBE at UTR-KINKI. The experiment measures the neutron counts using four detectors outside the reflector, and the power distribution was found to be well reconstructed. Furthermore, the present study estimates the power distribution using only two detectors for confirming the effect of power correlation. When the control rod had a large impact on detectors, estimated power distribution was emphasized. By contrast, small control rod effect cases suggested the advantage of PHOEBE. However, a more complex experimental geometry, such as a multi-layered fuel region, is required to more clearly evaluate the effect of considering the power correlation between fuel regions.

Bio-waste eggshell membrane assisted synthesis of NiO/ZnO nanocomposite and its characterization: Evaluation of antibacterial and antifungal activity

This paper presents the synthesis of NiO/ZnO nanocomposite using a bio-waste eggshell membrane as a template, which is used to control the particle size. It is a two-step process, soaking followed by the calcination method. The synthesized NiO/ZnO nanocomposite was characterized by the following techniques: Powdered X-ray diffraction analysis (PXRD), Ultra-Violet Visible spectroscopy (UV–Visible), Fourier transformed infra-red spectroscopy (FT-IR), Raman spectroscopy, Dynamic Light Scattering analysis (Zeta potential & particle size), Field Emission Scanning Electron Microscope (FE-SEM) with Energy Dispersive X-ray Analysis (EDX), and Hi-ResolutionTransmission electron microscope (HR-TEM) respectively. The NiO/ZnO nanocomposite exists in both face-centered cubic (NiO) and hexagonal wurtzite (ZnO) structures, according to PXRD results. The crystallite size was equal to 14.12 nm (NiO) and 14.70 nm (ZnO). The UV–Visible spectrum showed the wavelength at 302 nm and 372 nm, which indicates the presence of NiO and ZnO. The peaks at 449 cm−1 and 550 cm−1 are due to the stretching vibration of (Ni-O) NiO2 octohedral in the cubic NiO and the stretching vibration of ZnO. A Raman vibrational mode confirms the formation of the NiO/ZnO nanocomposite. The zeta potential analysis of the NiO/ZnO nanocomposite was equal to −42.7 mV, which indicates good stability, and the particle size distribution was equal to be 205.8 nm with a polydispersity index value of 0.5940. The SEM images of the NiO/ZnO nanocomposite appeared aggregated with small rods. The EDX spectra confirmed the presence of nickel, oxygen, and zinc, respectively. TEM images of the NiO/ZnO nanocomposite showed the particle size is less than 50 nm. The synthesized NiO/ZnO nanocomposite was subjected to antibacterial and antifungal activity by the agar-well diffusion method. The results demonstrated that the zone of inhibition of NiO/ZnO nanocomposite was high in Bacillus subtilis (30 ± 0.88 mm) for bacterial pathogens and Aspergillus terreus (30 ± 0.0 mm) for fungal pathogens, respectively. The minimum inhibition concentration (MIC) of NiO/ZnO nanocomposite was tested for bacterial pathogens. The results showed that the synthesized NiO/ZnO nanocomposite inhibited cell growth even at the lowest concentration (9.37 μg/mL). So it is inferred that the NiO/ZnO nanocomposite could act as an antifungal and antibacterial agent for a wide range of diseases.

Bartonella machadoae sp. nov. isolated from wild rodents in the Pantanal wetland

It has been estimated that 75% of emerging infectious diseases comprise zoonoses, whose majority have free-living animals as reservoirs and are mainly transmitted by arthropod vectors. Although rodents represent important Bartonella reservoirs, there are few studies on the genotypic characterization of Bartonella species commonly found in this taxon and from different Brazilian biomes. Therefore, the present study aimed to investigate the occurrence, isolate and molecularly, morphologically and phenotypically characterize a new Bartonella species infecting free-living rodents sampled in the Brazilian Pantanal, the largest wetland in South America. For this purpose, 129 free-living rodents (79 Thrichomys fosteri, 4 Clyomys laticeps, and Oecomys mamorae) were captured. While blood samples were collected from 57 T. fosteri, 4 C. laticeps and 32 O. mamorae; spleen samples were collected from 22 T. fosteri and 14 O. mamorae. Blood and spleen samples were submitted to a qPCR for Bartonella spp. targeting the nuoG gene, using DNA samples extracted directly from blood/spleen, after passage in pre-enrichment liquid culture, and from colonies obtained from solid culture on chocolate agar. Combining all techniques, occurrence of 24.8% for Bartonella sp. was found among the sampled rodents. One Bartonella isolate (strain 56A) obtained from a T. fosteri’s blood sample was closely related to the Bartonella vinsonii complex and selected for Whole Genome Sequencing (WGS) hybrid approach using Illumina NovaSeq and Nanopore sequencing platforms. This strain exhibits a circular 2.7 Mbp genome with an average C+G content of 39% and encoding to 2239 genes. In the phylogenomics based on 291 shared protein-coding genes, this strain was positioned in a unique clade, closely related to Bartonella vinsonii subsp. vinsonii, B. vinsonii subsp. berkhoffii and B. visonii subsp. arupensis. An Average Nucleotide Identity of 85% was found between the obtained isolate and Bartonella species belonging to B. vinsonii complex. These findings supported the separation of this strain, now formally named as Bartonella machadoae sp. nov., from the Bartonella vinsonii complex. In addition, Bartonella machadoae sp. nov. was characterized by capnophilic, microaerophilic and aerobic small rods with absence of pili and flagella. Phylogenetic and distance analyses based on five concatenated molecular markers suggest that Bartonella machadoae may parasite rodents from different Brazilian biomes. In conclusion, we described biochemical, phenotypic and genomic characteristics of Bartonella machadoae nov. sp. isolated from blood samples of T. fosteri rodents from the Brazilian Pantanal.

Morphology Influence on Wettability and Wetting Dynamics of ZnO Nanostructure Arrays

Abstract Changes in nanostructure morphology and size may result in very different surface wettability. In this research, the impact of different morphological parameters on the wetting dynamics of ZnO nanostructured layers is studied. Six different morphologies are chosen to determine the specific wetting processes of ZnO nanostructures: nanoneedles, small diameter rods, large diameter rods, nanotubes, nanoplates, and plain thin films. Wetting dynamics is investigated using conventional sessile drop technique and a novel approach based on electrochemical impedance spectroscopy. The results show that the surface of nanostructured ZnO thin films exhibits both hydrophilic and hydrophobic wetting behaviour, depending on nanostructure form, size, and orientation. ZnO nanostructure arrays are a promising platform for electrochemical and optical sensing in aqueous solutions. The full and effective use of the sensor working surface can be ensured only under the condition of complete wetting of the nanostructured layer. Therefore, it is important to take into account the peculiarities of the wetting process of a specific morphology of nanostructures.