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The FurnaSEM microfurnace was installed in the chamber of a scanning electron microscope to carry out in situ experiments at high temperatures and test its limits. The microfurnace was used in combination with different types of detectors (Everhart–Thornley for the collection of secondary electrons in a high vacuum, gas secondary electron detector for the specific collection of secondary electrons in the presence of gas, and Karmen© detector for the collection of backscattered electrons at high temperature). Experiments carried out on various samples (metal alloys and ceramics) show that the microfurnace operates in both high-vacuum and low-vacuum modes. Temperature ramp rates during temperature cycles applied to the sample range from 1 to 120 °C/min (temperature rise) and 1 to 480 °C/min (controlled and natural cooling). The maximum temperature at which images were recorded up to 25 k × magnification was 1340 °C, with a residual air atmosphere of 120 Pa. The choice of a flat furnace with the sample placed directly above it has enabled innovative experiments to be carried out, such as low-voltage imaging (using a shorter working distance—up to 10 mm—than is possible with conventional furnaces), 3D imaging (by tilting the stage by up to 10°), and high-temperature backscattered electron imaging (using a dedicated detector). [ABSTRACT FROM AUTHOR]

This paper describes the methodology of combining experimental measurements with mathematical–physics analyses in the investigation of flow in the aperture and nozzle. The aperture and nozzle separate the differentially pumped chamber from the specimen chamber in an environmental scanning electron microscope (ESEM). Experimental measurements are provided by temperature and pressure sensors that meet the demanding conditions of cryogenic temperature zones and low pressures. This aperture maintains the required pressure difference between the chambers. Since it separates the large pressure gradient, critical flow occurs on it and supersonic gas flow with the characteristic properties of critical flow in the state variables occurs behind it. As a primary electron beam passes through the differential pumped chamber and the given aperture, the aperture is equipped with a nozzle. The shape of the nozzle strongly influences the character of the supersonic flow. The course of state variables is also strongly influenced by this shape; thus, it affects the number of collisions the primary beam's electrons have with gas molecules, and so the resulting image. This paper describes experimental measurements made using sensors under laboratory conditions in a specially created experimental chamber. Then, validation using mathematical–physical analysis in the Ansys Fluent system is described. [ABSTRACT FROM AUTHOR]

The specific features of application of a low-energy atomic-force microscope (AFM) for studying the dynamic process of face growth in terms of the fluctuation model of crystal growth are discussed. It is shown that the probe interaction with an area of growing crystal surface on the time scale characteristic of a sequence of free energy fluctuations is a limiting factor for constructing an image of growing face surface. Agreement between the phenomenological and quantum (according to the uncertainty relation) descriptions of the effect of limiting magnification for a growing crystal face in an AFM is demonstrated. Specific features of detecting a growth stage on a crystal face using a transmission/scanning high-resolution electron microscope in a gas medium are also discussed. The effect of ultimate magnification when observing crystal growth in an АFМ is a basis for discussing the concept of the transient state of matter in the topochemical reaction of crystal growth and the phenomenon of building particle. [ABSTRACT FROM AUTHOR]

To cool a high mobility two-dimensional electron gas (2DEG) at a GaAs–AlGaAs heterojunction to milliKelvin temperatures, we have fabricated low resistance Ohmic contacts based on alloys of Au, Ni, and Ge. The Ohmic contacts have a typical contact resistance of R C ≈ 0.8 Ω at 4.2 K, which drops to 0.2 Ω below 0.9 K. Scanning electron microscope images establish that the contacts have the same inhomogeneous microstructure that has been observed in previous studies. Measurements of the contact resistance R C , the four-terminal resistance along the top of a single contact, and the vertical resistance RV all show that there is a superconductor in the Ohmic contact, which can be turned completely normal with a magnetic field of 0.15 T. We briefly discuss how this superconductivity may be affecting the electrical transport measurements of 2DEGs, especially how it may hinder the cooling of electrons in a 2DEG below 0.1 K. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents computed dependencies of signal amplification of detected electrons on the water vapor pressure in a variable pressure SEM using the EOD software equipped with a Monte Carlo plug-in. We analyze the amplification at selected energies of signal electrons going through a high-pressure water vapor and total signal amplification by including a realistic simulation of the secondary emission from sample. The results are compared with experimental measurements and the dependencies of published analytical models. [Copyright &y& Elsevier]

• Additive effect of thyme and betel leaf oil for C. gloeosporioides inhibition. • PVA nanofibres had oil loading capacity upto 75.88 %. • Developed nanofibres showed inhibition zone upto 24 cm in vitro. • Packing inoculated sapota with nanofibres reduced disease severity to 6.7 %. Control of anthracnose disease caused by Colletotrichum gloeosporioides by use of essential oils encapsulated in nanofibres made of polyvinyl alcohol has been attempted in this study. Essential oils from plants of subtropical origin, thyme oil and betel leaf oil were incorporated in electrospun mats at different levels. The Scanning Electron Microscope analysis revealed size of the nanofibers between 180 and 302 nm. Effective Dose (ED 50) values for the pure oils and their blends (1:3; 1:1; 3:1) ranged from 77 to 148 ppm. The blended essential oils demonstrated additive effect for inhibition of the pathogen with Abbott index >0.5. Oil loading capacity, determined using Gas Chromatography Electron Capture Detector ranged from 40.15–75.88% and was found proportional to feed content. No major effect of incorporation of thyme oil and betel oil on polymeric structure was observed in Fourier-transform infrared spectra. A Band near 876cm−1 and 1250 cm−1 signified the presence of both thyme and betel oil respectively. The composite nanofibers with blended oils at three levels showed inhibition zone from 6.6 mm to 11.6 mm on 3rdday of incubation, which increased further upto 24 mm on the 6th day. Sapota fruits inoculated with Colletotrichum gloeosporioides recorded disease severity of 83.33 %, 8.39 % and 6.72 % when packed in corrugated fiber board boxes with composite nanofibers as compared to control fruits (100 %) on the 6th day of incubation at 28 °C. Burning symptoms on skin were observed on fruits kept in contact with same level of essential oil infused sterile cotton balls highlighting the importance of encapsulated oils for disease control. [ABSTRACT FROM AUTHOR]

The low porosity and pore connectivity of ultrahigh molecular weight polyethylene (UHMWPE) membranes reduced membrane performance and limited its application in water treatment. In this work, the bimodal porous structure including two different grades and independent pore size distributions was constructed in UHMWPE membrane via thermally induced phase separation and sodium chloride (NaCl) leaching (TIPS-NL). Large pores (5–10 μm) were connected by small pores (0.09–0.15 μm), in which both pore sizes can be adjusted independently. When the large pores content is 35 vol% of the small pores, the water permeance of the separation membrane reaches 1177 L/(m2 h bar), which is about 16 times higher than that of the single-distributed small pores 74 L/(m2 h bar), and the particle, whose size is larger than 0.16 μm, can be well intercepted. Because the content of small pores in the bimodal porous structure is enough to separate the large pores, the rejection property of the UHMWPE membrane is also preserved. According to the particle size to be separated, the rejection ratio and permeance can be improved by simply adjusting the size and content of small and large pores. This work provided a new perspective for the fabrication of high-performance UHMWPE membranes by TIPS-NL. Image 1 • Bimodal porous structure with independent pore size distributions was constructed. • The pore size of bimodal porous structure can be adjusted independently. • The permeance can be improved effectively while remaining rejection property. • Scanning electron microscope and gas bubble pressure methods reveal the separation mechanism of bimodal porous structure. [ABSTRACT FROM AUTHOR]

• The effects of the scattered electrons in the gas on the X-ray lateral resolution is characterized using two adjacent materials. The e-beam is scanned across the Al-Cu interface for various experimental conditions of energy and pressure. Under low pressures and high energies, the EDS profiles have the same sigmoid shape as those acquired in high-vacuum. For high pressures and low energies, the sigmoid shape becomes enlarged and flatter. These results show how the scattered electrons by the gas entities can modify the shape of the EDS profile, causing the degradation of the X-ray spatial resolution. In this paper, our previously developed model to account for the secondary X-ray fluorescence and absorption effects near the interface of two adjacent materials in a high-vacuum scanning electron microscope (Zoukel & Khouchaf, 2014) is adapted and extended to experimental conditions of low-vacuum mode (in the presence of a gaseous environment in the SEM analysis chamber). The position shifting effect of the two Gaussian peaks issued from the first derivative equation that can fit the experimental low-vacuum EDS profiles is investigated. The impact of the medium gas on the emission volume of secondary X-rays near the interface is qualitatively discussed. Water vapour and helium are successively used as gas environment, in order to link the resolution of microanalysis profiles with the effects of the X-ray fluorescence and absorption phenomenon. A close agreement between Monte Carlo simulation and experimental results is found. X-ray Al k lateral resolution as the gas is introduced inside the analysis chamber of the VP-SEM using two adjacent materials. Image, graphical abstract [ABSTRACT FROM AUTHOR]