Tabletop Scanning Electron Microscope Research Articles

Effect of Wet-Dry Cycling on the Microstructure of Various Weathering Grade Sandstone

This study investigated the effect of rock-water interaction on microstructural properties of various weathering grade sandstone. Sandstone samples were acquired from the Sor-Range coal mine area, Pakistan, and were investigated using a tabletop scanning electron microscope (SEM). The characteristics of microstructures from micrographs were obtained using ImageJ software. According to the findings an increase in wet and dry cycles significantly affects the microstructures (pore spaces and microcracks). The porosity and microcracks density of sandstone increases with the number of wet and dry cycles. Furthermore, the length of microcracks increases as the weathering grade increases. As variation in rock macroscopic mechanical characteristics is directly associated with the deterioration of microstructures. Therefore, analyzing the effect of water-rock interaction in various weathering grades of rock can offer a more accurate reference index for assessing the stability of geotechnical structures.

Chemical Structure Comparison via Scanning Electron Microscopy of Spent Commercial Nickel-Metal Hydride Batteries.

Back-scattered electron imaging and X-ray elemental mapping were combined in a tabletop scanning electron microscope (SEM) to investigate cross-sections of three AA-type (mignon) nickel-metal hydride (NiMH) batteries from different manufacturers. All batteries underwent 500-800 charge/discharge cycles and reached their end of lifetime after several years as they could no longer hold any significant electric charge (less than 20% of nominal charge capacity), but none showed any short-circuiting. The types of degradation observed in this field study included electrode swelling, metallic nickel formation and carbon incorporation into pores in the positive electrodes and, in the negative electrodes, metal alloy segregation of different elements such as nickel, lanthanum and, in one case, sodium, as well as grain break-up and pore formation. All these phenomena could readily be observed at rather small magnifications. This will be important for the improvement of NiMH batteries, for which new generations with nominally slightly increased charge capacities are being marketed all the time.

Rapid Detection of Imipenem Resistance in Gram-Negative Bacteria Using Tabletop Scanning Electron Microscopy: A Preliminary Evaluation.

Background: Enabling faster Antimicrobial Susceptibility Testing (AST) is critical, especially to detect antibiotic resistance, to provide rapid and appropriate therapy and to improve clinical outcomes. Although several standard and automated culture-based methods are available and widely used, these techniques take between 18 and 24 h to provide robust results. Faster techniques are needed to reduce the delay between test and results.Methods: Here we present a high throughput AST method using a new generation of tabletop scanning electron microscope, to evaluate bacterial ultra-structural modifications associated with susceptibilities to imipenem as a proof of concept. A total of 71 reference and clinical strains of Gram-negative bacteria were used to evaluate susceptibility toward imipenem after 30, 60, and 90 min of incubation. The length, width and electron density of bacteria were measured and compared between imipenem susceptible and resistant strains.Results: We correlated the presence of these morphological changes to the bacterial susceptibility and their absence to the bacterial resistance (e.g., Pseudomonas aeruginosa length without [2.24 ± 0.61 μm] and with [2.50 ± 0.68 μm] imipenem after 30 min [p = 3.032E-15]; Escherichia coli width without [0.92 ± 0.07 μm] and with [1.28 ± 0.19 μm] imipenem after 60 min [p = 1.242E-103]). We validated our method by a blind test on a series of 58 clinical isolates where all strains were correctly classified as susceptible or resistant toward imipenem.Conclusion: This method could be a potential tool for rapidly identifying carbapenem-resistance in Enterobacterales in clinical microbiology laboratories in <2 h, allowing the empirical treatment of patients to be rapidly adjusted.

Scanning Electron Microscope: A New Potential Tool to Replace Gram Staining for Microbe Identification in Blood Cultures.

Blood culture is currently the most commonly used method for diagnosing sepsis and bloodstream infections. However, the long turn-around-time to achieve microbe identification remains a major concern for clinical microbiology laboratories. Gram staining for preliminary identification remains the gold standard. We developed a new rapid strategy using a tabletop scanning electron microscope (SEM) and compared its performance with Gram staining for the detection of micro-organisms and preliminary identification directly from blood cultures. We first optimised the sample preparation for twelve samples simultaneously, saving time on imaging. In this work, SEM proved its ability to identify bacteria and yeasts in morphotypes up to the genus level in some cases. We blindly tested 1075 blood cultures and compared our results to the Gram staining preliminary identification, with MALDI-TOF/MS as a reference. This method presents major advantages such as a fast microbe identification, within an hour of the blood culture being detected positive, low preparation costs, and data traceability. This SEM identification strategy can be developed into an automated assay from the sample preparation, micrograph acquisition, and identification process. This strategy could revolutionise urgent microbiological diagnosis of infectious diseases.

STEM takes flight

STEM is about the integration of science, technology, engineering and mathematics. To teach STEM effectively, students need practical examples of subject integration. A good example is the use of an electron microscope in teaching physics and biology. An electron microscope is an instrument in which the operation depends on electromagnetism and quantum mechanics, in particular wave-particle duality. In teaching physics, an electron microscope can be used to measure the separation of repeated structures that give rise to interference phenomena. This paper describes the use a tabletop scanning electron microscope to teach physics and biology together through imaging butterfly wings. Students are able to identify structures with a spacing comparable to visible light on butterflies exhibiting structural colour and much larger spacing on wings without structural colour.

Properties and Filtration Performance of Porous Clay Membrane Produced Using Sawdust as Pore Forming Agent

This study investigated the effect of sawdust at 0, 10, 20, 30 and 40 wt% towards physical properties and filtration efficiency of porous clay membrane. Sawdust in various quantities was added into water containing clay, polyethylene glycol and sodium silicate and then stirred to form homogenized slurry. The slurry then was casted into Plaster of Paris (PoP) mould. The green body was cut into required sizes, dried and sintered in furnace at 1000 °C. The porosity and density of porous clay was determined by Archimedes principle, while morphology was observed by Hitachi Tabletop Scanning Electron Microscope (TTSEM). The filtration test was examined on a dead-end filtration setup in batch mode operation using nitrogen as carrier gas. Distilled water was filtered and used to determine membrane permeability, while aquaculture wastewater filtration was used to determine the turbidity removal. Turbidity of aquaculture wastewater and effluent (after filtration) were measured using turbidity meter. The results indicated that porosity increased from 38 % to 64 %, while density decreased from 1.5 g/cm3 to 0.8 g/cm3 with increasing amount of sawdust from 0 to 40 wt%. This data was supported by TTSEM which is indicate that the amount of pores increased with increasing amount of sawdust. Permeation of membrane increased from 45289 to 143999 L.h-1.m-2.bar-1 and efficiency of turbidity removal increased from 87 % to 89 % with increasing amount of sawdust from 0 to 40 wt%. As conclusion, 30 wt% was an optimum amount of sawdust which is produced ceramic membrane with good structure integrity, porosity, high permeability and high turbidity removal.

High-throughput isolation of giant viruses using high-content screening

The race to discover and isolate giant viruses began 15 years ago. Metagenomics is counterbalancing coculture, with the detection of giant virus genomes becoming faster as sequencing technologies develop. Since the discovery of giant viruses, many efforts have been made to improve methods for coculturing amebas and giant viruses, which remains the key engine of isolation of these microorganisms. However, these techniques still lack the proper tools for high-speed detection. In this paper, we present advances in the isolation of giant viruses. A new strategy was developed using a high-throughput microscope for real-time monitoring of cocultures using optimized algorithms targeting infected amebas. After validating the strategy, we adapted a new tabletop scanning electron microscope for high-speed identification of giant viruses directly from culture. The speed and isolation rate of this strategy has raised the coculture to almost the same level as sequencing techniques in terms of detection speed and sensitivity.

Using a Tabletop Scanning Electron Microscope as an Outreach Tool to Engage the Public With Cutting-edge Research

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Wide-range tunable magnetic lens for tabletop electron microscope

A tabletop scanning electron microscope (SEM) utilizes permanent magnets as condenser lenses to minimize its size, but this sacrifices the tunability of condenser lenses such that a tabletop system can only be operated with a fixed accelerating voltage. In contrast, the traditional condenser lens utilizes an electromagnetic coil to adjust the optical properties, but the size of the electromagnetic lens is inevitably larger. Here, we propose a tunable condenser lens for a tabletop SEM that uses a combination of permanent magnets and electromagnetic coils. The overall dimensions of the newly designed lens are the same as the original permanent magnet lens, but the new lens allows the tabletop SEM to be operated at different accelerating voltages between 1kV and 15kV.

Heavy Metals in Mollusc Shells: A Quick Method for their Detection

It is known for a long time that calcified tissues secreted by aquatic or terrestrial invertebrates – such as mollusc shells – have the ability to concentrate large amounts of pollutants, in particular heavy metals. In the present paper, we have found an extremely rapid and easy procedure to qualitatively detect the putative presence of heavy metals in shells, without having to use sophisticated techniques such as Wavelength Dispersive Spectroscopy, atomic adsorption spectroscopy or ICP-MS. Our method rests on the capacity of the silver enhancement chemicals that are traditionally used in immunogold localization experiments to increase the size of heavy metal nanoparticles, whatever the chemical element. It goes as follows: freshly broken pieces of shells that are suspected to contain traces of heavy metals are simply incubated 15 minutes in few drops of a silver enhancement solution (British Biocell International), and, after short rinsing and drying, the shell fragments are directly observed with a tabletop Scanning Electron Microscope, under back scattered electron (BSE) mode without any further preparation. Heavy metals nanoparticles are detected as bright spots. Our method is extremely fast (about half an hour in total), and may be used as a quick check for pre-selecting series of calcified samples prior to the quantitative analysis of their heavy metal content.

卓上走査電子顕微鏡の開発とそれを用いた科学教育の振興支援活動

卓上走査電子顕微鏡の開発とそれを用いた科学教育の振興支援活動

Influence of Nitrogen Partial Pressure on the Microstructure and Properties of TiN Coatings

TiN coatings were prepared by using multi-arc ion plating technique at different N2 partial pressures. The surface morphology of the coatings was characterized by using a tabletop scanning electron microscope. The cross-sectional microstructure was investigated by using a field emission scanning electron microscope. The phase composition was evaluated by using an X-Ray diffractometer. The hardness and cohesion were measured by using a nanoindentation tester and a scratch instrument, respectively. The results show that the number and size of macro-particles decrease and the compactness of TiN coating increases with the increase of the N2 partial pressure. The hardness and cohesion of the coating increase gradually with increasing N2 partial pressures and reach a peak at 0.6 Pa; then the hardness and cohesion are significantly lower at higher N2 partial pressures.

Analysing the Micro Structure of Sea Sand Concrete

The microstructure of sea sand concrete wes characterized by the Accelerated Surface Area and Porosimetry System (ASAPS) to detect the concrete micro-prorous structure distribution, the Tabletop Scanning Electron Micro-scope (TSEM) to analysis the sea sand concrete internal microstructure, as well as the X-Ray Diffractometer (XRD) and the Thermal gravimetric/Differemtial Thermal Anylyzer (TG/DTA) to observe the composition of concrete in this paper. The influence on hydration processes of concrete caused by sea sand was reseached from four aspects which are the influences of fly ash on concrete, chlorine salts on sea sand concrete, chlorine salt on fly ash added sea sand concrete and desalination sea sand and not desalination sea sand concrete micro structure features to evaluate the effect of sea sand on regular sea sand concrete and fly ash added sea sand concrete micro structure features and chemical composition.

Quantitative analysis of cell distribution in injection molded microcellular foam

The microstructure of cellular materials, in particular microcellular polymers, is commonly characterized by the mean cell size and cell population density. Although the physical properties of foamed polymers are highly dependent on cell distribution, very insignificant work has been carried out to quantify the distribution of cells. This experimental study correlates the influential processing parameters of microcellular injection molding with the cell distribution, mean cell size and population density. For the first time, “Cell Distribution Index (CDI)”, a quantitative parameter for characterization of foams has been defined in this paper. Foamed samples of polystyrene were prepared via microcellular injection molding process. The design of experiment includes five influential processing parameters (factors) at five different levels. Molded samples were fractured cryogenically and micrographs were obtained using a table top scanning electron microscope. With the help of image processing package, mean cell size, cell population density, frequency and newly defined term CDI were calculated for each micrograph. Finally, the effect of processing parameters on cell distribution was analyzed by plotting the CDI against the processing parameters.

Present Distribution Of Pedunculate Barnacle Of Wild Mud Crab Scylla Olivacea From Setiu Wetland, Terengganu Coastal Water, Malaysia

Pedunculate, Goose or Stalked barnacles are commonly found in the hard substrate of marine or brackish area and it also recorded found attached on the living organisms as their host. Thirty seven wild mud crabs (Scylla olivacea) were sampled from Setiu Wetland (5°40’47.93”N, 102°42’45.04”E), Terengganu, Malaysia. The 625 sample of barnacles were collected and the samples were preserved in 70% alcohol and observed by using Table Top Scanning Electron Microscope (Hitachi TM1000). The morphology and characteristic of the barnacle were recorded based on the observation of their peduncle, capitulum, calcareous plates, carina, tergum and branched scutum. To our knowledge, there is no morphological study about the species of pedunculate barnacle that attached on gill of S. olivacea in Malaysia. Thus, this study provides the first report of pedunculate barnacle attached on S. olivacea in the east coast of peninsular Malaysia.

Evaluation of the Microanatomy of the Liver via a Rapid Sample Preparation Protocol and a Table-Top Scanning Electron Microscope

In this paper an alternative preparation and imaging method is presented that allows investigation of the fine structure of hepatic tissue within one hour after the initial fixation step. This approach involves, besides traditional fixation with glutaraldehyde, chemical drying and subsequent investigation of the samples with the new generation of user-friendly desktop scanning electron microscopes. The data presented herein reveal comparative preservation of liver ultrastructure to those that are prepared using classical sample preparation protocols. This low-cost approach permits the swift study of liver tissue subjected to various testing conditions and hence bridges the time gap between experiment and subsequent ultrastructural observation at the nanoscale.

Table Top SEM Utilization in a High School Nanotechnology Course

Abstract A Duke University Talent Identification Program (TIP) nanotechnology course curriculum integrated a Hitachi TM-1000 table top scanning electron microscope (SEM) into the classroom to excite and educate gifted and talented high school students interested in this emerging field of research. Students learned about synthesis, characterization and applications of nanotechnologies to encourage them to begin thinking about why and how properties of matter change at the nanoscale. The syllabus was created to introduce fundamental concepts like introductory quantum mechanics, atomic bonding, allotropes of carbon and applications including nanomedicine, nanoelectronics, nano-textiles, bionanotechnology and nanometals. The classroom environment allowed students to take intellectual risks and the course content was presented through a variety of methods to utilize the Kolb learning model and encompass intellectual, personal, social and practical learning methods. The teaching approaches employed traditional principle based lectures, but also included guest speakers, experiential learning activities and both project or problem based learning laboratories.