Uniform Morphological Features Research Articles

Semiconducting and gas sensing performance of Magnetite nanoparticle systems of different morphologies

Magnetite nanoparticle systems with uniform morphological features were synthesized through co-precipitation and forced hydrolysis without using any surfactants or additives. The selected batches of the synthesized particle systems were calcined at 1200 °C for phase transformation. The as-synthesized and calcined samples were characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectrometry (FTIR), and X-ray Diffraction (XRD). In addition, the as-prepared and commercial magnetite particles were then employed as gas sensors to detect ammonia. Furthermore, the semiconducting properties of the synthesized (magnetite-I magnetite-II & magnetite-III) and commercial magnetite-based sensors were studied in the temperature range from 30 °C to 270 °C which indicated the n-type semiconducting nature of the magnetite particles. While commercial magnetite did not show any response in the employed temperature range. Furthermore, the synthesized magnetite nanoparticle-based sensors showed good and highly reproducible performance toward 10 ppm ammonia with a gas response of 58.44%, 64.39%, and 59.02%, respectively. For instance, magnetite-II and III were more sensitive toward the detection of ammonia with quick response/recovery times of 2s/5.8s and 2.4s/6.2s than 40s/17s for magnetite-I-based sensors. In contrast, the commercial magnetite-based sensor showed a response of 13.59% and significantly longer response/recovery time at room temperature and did not respond to ammonia concentration even at high temperatures. It was attributed to the remarkable uniformity in morphology, porosity, and good crystallinity of the as-prepared nanoparticles compared to the commercial-based sensor. This study unfolds that morphological features of the gas sensor’s material could be the key factors for controlling their sensing properties.

Surfactant-Free Facile Synthesis of Nickel Oxalate Monodispersed Particles in Novel Morphologies

The surfactant or shape modifier used in the synthesis of monodispersed uniform fine particles affected the performance of the prepared powder in its applications. The present investigation is related to synthesizing colloidal uniform fine particles of nickel oxalate in novel morphologies under an optimized set of reaction conditions without using any surfactant or shape modifier. SEM results revealed that the reactant concentration significantly affected the characteristics of the precipitated solids, which ranged from gel to dispersion of discrete particles. Particles of uniform morphological features were obtained under an optimized set of experimental conditions, i.e., reactant concentration, temperature, aging time, etc. The molar ratio of the precursors affected the particle’s growth mechanism as the spherical morphology of the particles changed to a cubic shape by increasing nickel ion concentration in the recipe at 25 oC. The cubic morphology transformed into toffee shape bigger particles of a 0.5 axial ratio by increasing the reaction mediumand#39;s thermal energy. The synthesized particles were characterized by various physical techniques, which confirmed the product as the monodispersed pure NiC2O4.2H2O particles.

First report of charcoal rot caused by Macrophomina phaseolina on potato tubers in Mauritius.

Charcoal rot, caused by Macrophomina phaseolina, is an important disease in tropical and subtropical regions which affects a broad range of host plants, including potato (Solanum tuberosum L.). In this crop, charcoal rot can reduce the marketable quality of tubers (Arora 2012) and cause yield losses up to 88% (Somani 2007). During a survey of a potato field of 'Spunta' cultivar in Goodlands, Mauritius (20°02'28.2"S 57°39'30.4"E) approximately 10% of tubers with grey pigmentation around the lenticels and small water-soaked spots with white dots were observed. These symptoms later advanced to dark brown to black patches on the skin surface, all conforming to typical symptoms of charcoal rot (Arora and Khurana 2004). Fragments of infected and adjacent healthy tissue were cut, thoroughly washed with tap water, surface sterilized for 30 s with 1% sodium hypochlorite (25% bleach), placed on chloramphenicol-amended Potato Dextrose Agar (PDA), and incubated for 5 days in the dark at 25±2oC. From all the inoculated plates, only fast-growing, dark brown, grey to black Macrophomina-like colonies grew and several mono-sclerotial isolates were obtained with uniform morphological features. Following staining with cotton lactophenol dye using the clean slide technique, the isolate 449G-19/M exhibiting typical characteristics of M. phaseolina (Arora and Dhurwe 2019) and forming flattened, globose, black sclerotia with an average diameter of 180 µm (n= 50), was selected and used for further characterization. Identification was confirmed by sequencing of the ITS region of rDNA. Total DNA was extracted directly from the mycelium using a DNeasy Plant Mini Kit (Qiagen, Hilden, Germany), following the manufacturer's instructions, while PCR amplification and sequencing were performed with primers ITS1-F (Gardes and Bruns 1993) and ITS-4 (White et al. 1990). The nucleotide sequence of the isolate 449G-19/M (Accession No. MW301138) shared 98.28 to 99.80% similarity with over 70 M. phaseolina isolates in GenBank (99.18% with isolate from Zea mays, Accession No. KF531825 (Phillips et al. 2013)). Pathogenicity was tested on 20 healthy tubers which were initially disinfected with 2% sodium hypochlorite for 1 min and individually placed in pots (20 cm ø) containing sterile substrate. Ten tubers were inoculated by placing colony fragments of 7-day-old cultures of the isolate 449G-19/M near each tuber. Similarly, 10 tubers inoculated with sterile PDA served as a negative control. The plants were maintained in greenhouse conditions, watered daily, and assessed for the presence of symptoms 8 weeks post emergence. All inoculated tubers exhibited charcoal rot on progeny tubers while control plants remained symptomless. Koch's postulates were fulfilled successfully and the fungus recovered from the inoculated plants. Although M. phaseolina was previously observed in Mauritius on groundnut resulting in pre-emergence rot and collar rot (Anonymous 1962), to our knowledge, this is the first report demonstrating charcoal rot on potato tubers caused by M. phaseolina in Mauritius. As the sclerotia can remain in the soil for long periods of time (Arora and Khurana 2004) and with prevailing conditions of global warming, charcoal rot may be a threat for potatoes and other local crops (Somani et al. 2013). This study will sensitize agricultural extension officers on this new disease and calls for routine surveillance to safeguard this crop.

Mechanical characterization of FDM filaments with PVDF matrix reinforced with Graphene and Barium Titanate

In past one decade number of studies has been reported on optimization of process parameters of fused deposition modelling (FDM) for in-house developed thermoplastic composite based feed stock filaments. This paper investigates smart polymer-based composites prepared with hybrid feed stock filament (comprising of polyvinylidene fluoride (PVDF) reinforced with graphene (Gr) and barium titanate (BTO) powder). This work started with the Functional prototypes were 3D printed for tensile and flexural characterization using inhouse developed filament (PVDF (78%)+Gr (2%) with BTO (20%)) at optimized settings of FDM. The printed specimens were subjected to destructive testing for mechanical properties (to analyze the process capability indices, Cp and Cpk). For morphological properties, scanning electron microscopy (SEM) images and 3D rendered images of the fractured surfaces of tensile and flexural specimen were used. It has been revealed from the SEM and 3D rendered images that the optimized settings of 3D printing process parameters resulted into uniform morphological features (based upon surface roughness (Ra) and amplitude distribution function (ADF), peak count (PC) and bearing ratio (BR) curve).

3D printed tensile and flexural prototypes of thermoplastic matrix reinforced with multi-materials: A statistical analysis

Fused deposition modelling (FDM) is one of the established low cost 3D printing techniques for preparation of functional/ non functional prototypes from thermoplastic composite matrix (prepared as multi/ hybrid blended material). But hitherto little has been reported on multi material reinforced thermoplastic matrix in successive 3D printed layers from repeatability view point. Since the adaptability of any processing technique is dependent upon repeatability/ reproducibility (for which the process output must be statistically controlled), this work reports the statistical analysis of 3D printed tensile and flexural samples printed on FDM as functional prototypes of poly lactic acid (PLA) matrix reinforced with multi materials (poly vinyl chloride (PVC), wood dust and magnetite (Fe 3 O 4 ) powder) as functionally graded thermoplastic matrix. Further in this work functional prototypes of tensile and flexural sample were 3D printed and tested for their mechanical properties to analyze the process capability index (Cp and Cpk) along with morphological characteristics using optical images of the fractured surfaces. The result of the study suggests that the process was observed to be in statistical control as Cp and Cpk was found to be more than 1 for tensile and flexural properties. Based upon optical photo micrographs it has been ascertained that the optimized 3D printing parameters resulted into uniform morphological features (based upon surface roughness (Ra) and amplitude distribution function (ADF), peak count (PC) and bearing ratio (BR) curve).

Morphology controlled synthesis of ZnO nanoparticles for in-vitro evaluation of antibacterial activity

Abstract Novel hierarchical flower- and nanorod-shaped ZnO nanoparticles with uniform morphological features were successfully synthesized through controlled precipitation method in aqueous media without using any surfactant or template. To elucidate the growth mechanism of the synthesized nanoparticles, the effects of pH, reaction time and temperature were studied systematically. Selected ZnO samples were then subjected to SEM, FT-IR and XRD analysis. XRD patterns confirmed well crystalline nature of the as-synthesized powders. Furthermore, synthesized nanoparticles (hierarchical flowers as ZnO-1 and nanorods as ZnO-2), as well as commercial ZnO (ZnO-Com), were then investigated for in-vitro evaluation of antibacterial activity against various bacterial strains of clinical importance. Results showed that ZnO-2 exhibited higher antibacterial activity to all tested strains than ZnO-1, while ZnO-Com showed no antibacterial response in the applied experimental conditions. In addition, ZnO concentration-dependent antibacterial study unfolded that size of inhibition zones increased significantly from ~30 to 33 mm against Streptococcus mutans and from ~28 to 30 mm against Escherichia coli with increasing ZnO-2 concentration from 0.25 to 0.75 µg/µL. The present study, therefore, suggests that the application of synthesized ZnO nanoparticles as the antibacterial agent may be effective for inhibiting certain pathogenic bacteria in biomedical sides.

Influence of NaCl-salinity on Pb-uptake behavior and growth of River Red gum tree (Eucalyptus camaldulensis Dehnh.)

Lead (Pb) is one of the most toxic and persistent elements, with no known biological role. High concentrations of lead enter saline soils through anthropogenic activities and industrial waste. The decontamination of Pb polluted sites through phytoremediation, especially by using woody plants, is an attractive approach. Eucalyptus camaldulensis is a good accumulator of Pb and a recommended tree species for reclamation of saline soils. However, there is very limited knowledge about the Pb-uptake behavior of Eucalyptus camaldulensis under saline conditions. The objective of this study was to examine the simultaneous impact of NaCl salinity and Pb stress on the phytoremedial potential and growth behavior of E. Camaldulensis. Six-week-old Eucalyptus camaldulensis plants with uniform morphological features were transferred into hydroponic conditions, and they were exposed to the NaCl salinity stress at 200 mM and Pb stress at 10 mg L-1 and 20 mg L-1 (Pb1 and Pb2, respectively). The plants showed a 100% survival rate in all treatments. All the morphological parameters (plant height, plant diameter, and shoot dry weight) for E. Camaldulensis were significantly affected when exposed to Pb or Pb + NaCl-salinity, with the exception of root length which was 36% higher in Pb2 as compared to the control. The Pb uptake (mg Pb plant-1) was much higher (49.3) under Pb2 + NaCl-salinity, as compared to the control (1.2) and other treatments, which shows that saline conditions increased the Pb-uptake in E. Camaldulensis. The order of deposition of Pb (mg Pb kg-1 of dry weight) in plant parts was root (103.4) >> shoot (17.5) > leaves (13.6). Similarly, the bioconcentration factor (BCF) of the roots was 4 to 6 times higher than shoot BCF.

Pollen Morphology of Acinos Miller Species Growing in Turkey

Abstract The pollen morphology of six taxa of the genus Acinos Miller has been examined under scanning electron microscopy (SEM) and a description of each taxon has been given. Acinos pollen is stephanocolpate (hexacolpate). Two main exine sculpturing types, foveolate‐reticulate (only in subspecies of A. troodi) and reticulate, have been defined. The dimension for the polar length ranges between 25.8–47.4 μm, equatorial width 24.5–34.4 μm, colpus length 20.0–40.5 μm and colpus width 1.2–2.5 μm. The shape is mostly subprolate to prolate, seldomly prolate‐spheroidal. The results reveal rather uniform morphological features, however fine details are characteristic to differentiate the pollen taxa. Acinos pollen also share some common morphological features with the other Lamiaceae pollen.

Rigid telescopy and contact endoscopy in the diagnosis and surgery of Reinke’s oedema: Clinical and histological assessment

We focussed our attention on the use of both rigid telescopy and contact endoscopy in order to assess their effectiveness in the diagnosis and surgery of Reinke's oedema. Changes were observed in a sample of 40 patients, suffering from different stages of Reinke's oedema, who had undergone microlaryngoscopies. For the first time during our laryngological praxis, we discussed a number of parameters that appeared to be significant in the monitoring and detailed evaluation of this vocal fold disease. With contact endoscopy, during the early stages of the disease, the cells and nuclei of normal squamous layered epithelium continued to display uniform morphological features. The appearance of epithelial changes helps to distinguish between different stages of Reinke's oedema, which can be associated with severe inflammation or keratinisation. With latter-stage oedemas, the following was observed: various changes in the blood vessels of the glottis, which when viewed through the endoscope have an unusual "loop-like" or "branching" appearance, as well as elongated and varicose blood vessels, and the build-up of erythrocytes inside atypical capillaries. Both endoscope techniques are non-invasive and very appropriate for precisely diagnosing Reinke's oedema within a relatively short period of time. Rigid telescopy has the advantage of enabling the systematic observation of many details in the large area of both vocal fold mucosae, particularly when access to the larynx is difficult. This enables dynamic monitoring and immediate pathology consultations inside the operating theatre. The special contribution of contact endoscopy is that, both in vivo and in situ, it allows a detailed scanning and mapping to be performed of all cell changes and ofvascularisation throughout the entire mucosa surface. Video-assisted telescopy does not permit a completely first-rate surgical resection of Reinke's oedema, because of unsatisfactory control or insufficient stability of the instrument during the operation using the one-handed method.

Echocardiographic characteristics and outcome of straddling mitral valve

OBJECTIVESThis study sought to characterize the echocardiographic features of straddling mitral valve (SMV) and to determine its surgical implications and midterm outcome in a large clinical cohort.BACKGROUNDDespite a relatively large body of literature on the postmortem anatomy of SMV, there is a paucity of information regarding its echocardiographic features, surgical implications and preoperative predictors of outcome.METHODSA retrospective review identified 46 patients with SMV between 1982 and 1999 who underwent echocardiography and surgery and had follow-up data. A detailed review of the echocardiograms, surgical reports and all pertinent records was undertaken.RESULTSReview of the echocardiograms revealed a widely varying anatomy among the study patients. However, four distinct groups with relatively uniform morphologic features could be distinguished on the basis of segmental analysis. Cardiac malposition associated with right ventricular hypoplasia, superior-inferior ventricles and criss-cross atrioventricular relations were common among patients with {S,D,L} (S = visceroatrial situs solitus, D = D-ventricular loop, L = L-malposition of the great arteries) (n = 6) and {S,L,D} (n = 5) segmental combinations but were rare among patients with {S,D,D} (n = 26) and {S,L,L} (n = 9) combinations. Surgical management consisted of a functional single-ventricle palliation in 38 patients (83%) and biventricular repair in 8 patients (17%). Overall mortality was 22%, but none of the seven patients who were operated on during the cohort’s last five years (1994 to 1999) has died. By multivariate analysis, noncommitted ventricular septal defect was the strongest independent predictor of death (relative risk = 10.2), followed by multiple ventricular septal defects (relative risk = 4.7).CONCLUSIONSThis study demonstrates that echocardiography provides detailed noninvasive imaging of the complex anatomic features of SMV and its associated anomalies. Anatomic classification based on segmental analysis allows the distinction of four groups with more uniform morphologic features. Although a biventricular approach is feasible in selected patients, a functional univentricular palliation is indicated in those with major straddling and markedly hypoplastic ventricles.

Two Karyotypically Independent Leukemic Clones With the t(8;21) and 11q23 Translocation in Acute Myeloblastic Leukemia at Relapse

Leukemic blast cells are thought to arise from clonal expansion of a single transformed hematopoietic cell. This generality is supported by the rarity of convincing reports on acute myeloblastic leukemia (AML) with two karyotypically independent clones. Relying on sequential cytogenetic analyses, we identified such clones in two children with relapsed AML. The first case, classified as M2 leukemia in the French-American-British (FAB) classification system, had a t(8;21) (q22;q22) at diagnosis; 16 months later, at relapse, the leukemic cells had uniform morphologic features similar to those observed at diagnosis, except that two independent clones were present: one with the original t(8;21) and the other with t(11;22)(q23;q13) [corrected]). The second case was initially classified as FAB M1 leukemia with a t(8;21) (q22;q22). At relapse, 16 months later, the blast cells appeared morphologically uniform and similar to the diagnostic specimen; however, in addition to the original t(8;21) clone, there was a t(1;11) (p32;q23) [corrected]. These findings suggest that separate leukemogenic events affecting different progenitor cells can occur in rare cases of AML. The presence of two karyotypically independent clones could also be explained by multistep leukemogenesis; that is, more than one cell from a common pool of preleukemic cells could be affected by the transforming event, resulting in two independent clones. Alternatively, in light of recent reports of therapy-related leukemias with an 11q23 translocation, the new independent clone in these two patients could represent a therapy-related secondary malignancy. Thus, 11q23 translocations may occur preferentially in stem cells that are more susceptible to treatment-induced malignant transformation.

Two karyotypically independent leukemic clones with the t(8;21) and 11q23 translocation in acute myeloblastic leukemia at relapse [published erratum appears in Blood 1989 Aug 15;74(3):1180

Leukemic blast cells are thought to arise from clonal expansion of a single transformed hematopoietic cell. This generality is supported by the rarity of convincing reports on acute myeloblastic leukemia (AML) with two karyotypically independent clones. Relying on sequential cytogenetic analyses, we identified such clones in two children with relapsed AML. The first case, classified as M2 leukemia in the French- American-British (FAB) classification system, had a t(8;21) (q22;q22) at diagnosis; 16 months later, at relapse, the leukemic cells had uniform morphologic features similar to those observed at diagnosis, except that two independent clones were present: one with the original t(8;21) and the other with t(11;22)(q23;q13) [corrected]). The second case was initially classified as FAB M1 leukemia with a t(8;21) (q22;q22). At relapse, 16 months later, the blast cells appeared morphologically uniform and similar to the diagnostic specimen; however, in addition to the original t(8;21) clone, there was a t(1;11) (p32;q23) [corrected]. These findings suggest that separate leukemogenic events affecting different progenitor cells can occur in rare cases of AML. The presence of two karyotypically independent clones could also be explained by multistep leukemogenesis; that is, more than one cell from a common pool of preleukemic cells could be affected by the transforming event, resulting in two independent clones. Alternatively, in light of recent reports of therapy-related leukemias with an 11q23 translocation, the new independent clone in these two patients could represent a therapy-related secondary malignancy. Thus, 11q23 translocations may occur preferentially in stem cells that are more susceptible to treatment-induced malignant transformation.

Fine structure of human endocervical epithelium

The human endocervical epithelium has been studied with the electron microscope. It appeared to be composed of three kinds of cells: mucus columnar cells, ciliated cells, and reserve cells. The mucus columnar cells were seen as highly differentiated elements with most of their cytoplasm occupied by secretion. The secretion was complex in structure and appeared to be composed of a central core of high electron density surrounded by a finely reticular meshwork. The ciliated cells were scarce and presented cilia of the motile type. The reserve cells did not show uniform morphologic features. On the basis of electron micrographs indicating intermediate stages between the reserve and the mucus cells, it was suggested that the latter originate from the reverve cells.