Controlled dehydration of a biological sample using an alternative form of environmental SEM

2010 ◽  
Vol 237 (1) ◽  
pp. 7-11 ◽  
Author(s):  
V. NEDÄšLA
2001 ◽  
Vol 7 (S2) ◽  
pp. 46-47
Author(s):  
Manjun Shao ◽  
Lei Jiang

For industrial-scale culture of anchorage-dependent mammalian cell, such as vero cell, growth on the microcarriers offers certain advantages. As previous research reported, growth process can be illustrated by a growth curve - cell density versus time, which shows the change of cell density through whole growth process including: first adhesion stage; spreading and division stage; and last confluent stage. The growth curves are controlled by the culture condition (culture medium, temperature, pH value, inoculation concentration, etc.) and space condition (kind of microcarrier, microcarrier size, and surface property, etc.). Therefore, the cell growth curve is not only the important basis for studying growth kinetics, but also for designing biological reactors.Traditionally, total cell concentration for the microcarrier cultures were determined using the crystal violet method, and the cell nuclei were counted with a hemacytometer. in this method, the cells attached on each microcarrier were trypsinized and dyed by crystal violet dye, so that the number of nuclei counted was statistically representative. in this work, the cells and microcarriers were examined by using an environmental SEM - KYKY1500. As a result, the moist cells and microcarriers in SEM images show their natural characteristics, because this environmental SEM permits biological sample to be observed directly in an environmental specimen chamber without normal preparation for biological sample. As for the normal preparation, it needs a long duration, e.g. 2 days normally, to do fixing, desiccating and gold-coating. in contrast, the operation for observation of the biological samples in this SEM is much simpler. in view of this, a statistical counting method based on the SEM images for determining cell concentration during microcarrier culture was developed.


Author(s):  
Rebecca W. Keller ◽  
Carlos Bustamante ◽  
David Bear

Under ideal conditions, the Scanning Tunneling Microscope (STM) can create atomic resolution images of different kinds of samples. The STM can also be operated in a variety of non-vacuum environments. Because of its potentially high resolution and flexibility of operation, it is now being applied to image biological systems. Several groups have communicated the imaging of double and single stranded DNA.However, reproducibility is still the main problem with most STM results on biological samples. One source of irreproducibility is unreliable sample preparation techniques. Traditional deposition methods used in electron microscopy, such as glow discharge and spreading techniques, do not appear to work with STM. It seems that these techniques do not fix the biological sample strongly enough to the substrate surface. There is now evidence that there are strong forces between the STM tip and the sample and, unless the sample is strongly bound to the surface, it can be swept aside by the tip.


Author(s):  
G.D. Danilatos

The advent of the environmental SEM (ESEM) has made possible the examination of uncoated and untreated specimen surfaces in the presence of a gaseous or liquid environment. However, the question arises as to what degree the examined surface remains unaffected by the action of the electron beam. It is reasonable to assume that the beam invariably affects all specimens but the type and degree of effect may be totally unimportant for one class of applications and totally unacceptable for another; yet, for a third class, it is imperative to know how our observations are modified by the presence of the beam. The aim of this report is to create an awareness of the need to initiate research work in various fields in order to determine the guiding rules of the limitations (or even advantages) due to irradiation.


Author(s):  
G.D. Danilatos

The possibility of placing the specimen in a gaseous medium in the environmental SEM (ESEM) has created novel ways for detection of signals from the beam-specimen interactions. It was originally reported by Oanilatos that the ionization produced by certain signals inside the conditioning medium can be used to produce images. The aim of this report is to demonstrate some of the improvements on the system that have occurred thereafter.Two straight thin wires are aligned horizontally along a direction normal to the direction of the two scintillator backscattered electron (BSE) detectors reported elsewhere. The free end tips of the wires are about 5 mm apart halfway between the specimen and the pressure limiting aperture (specimen distance = 1.5 mm). The other end of each wire makes contact with the input of a separate preamplifier, two of which are built inside a shielding aluminum stub. With such a design, interference noise from the input cables is avoided.


Author(s):  
Klaus-Ruediger Peters

Environmental SEM operate at specimen chamber pressures of ∼20 torr (2.7 kPa) allowing stabilization of liquid water at room temperature, working on rugged insulators, and generation of an environmental secondary electron (ESE) signal. All signals available in conventional high vacuum instruments are also utilized in the environmental SEM, including BSE, SE, absorbed current, CL, and X-ray. In addition, the ESEM allows utilization of the flux of charge carriers as information, providing exciting new signal modes not available to BSE imaging or to conventional high vacuum SEM.In the ESEM, at low vacuum, SE electrons are collected with a “gaseous detector”. This detector collects low energy electrons (and ions) with biased wires or plates similar to those used in early high vacuum SEM for SE detection. The detector electrode can be integrated into the first PLA or positioned at any other place resulting in a versatile system that provides a variety of surface information.


2012 ◽  
Vol 21 (2) ◽  
pp. 60-71 ◽  
Author(s):  
Ashley Alliano ◽  
Kimberly Herriger ◽  
Anthony D. Koutsoftas ◽  
Theresa E. Bartolotta

Abstract Using the iPad tablet for Augmentative and Alternative Communication (AAC) purposes can facilitate many communicative needs, is cost-effective, and is socially acceptable. Many individuals with communication difficulties can use iPad applications (apps) to augment communication, provide an alternative form of communication, or target receptive and expressive language goals. In this paper, we will review a collection of iPad apps that can be used to address a variety of receptive and expressive communication needs. Based on recommendations from Gosnell, Costello, and Shane (2011), we describe the features of 21 apps that can serve as a reference guide for speech-language pathologists. We systematically identified 21 apps that use symbols only, symbols and text-to-speech, and text-to-speech only. We provide descriptions of the purpose of each app, along with the following feature descriptions: speech settings, representation, display, feedback features, rate enhancement, access, motor competencies, and cost. In this review, we describe these apps and how individuals with complex communication needs can use them for a variety of communication purposes and to target a variety of treatment goals. We present information in a user-friendly table format that clinicians can use as a reference guide.


CounterText ◽  
2015 ◽  
Vol 1 (1) ◽  
pp. 38-58 ◽  
Author(s):  
Caroline Rooney

The initial part of Caroline Rooney's essay offers an incisive account of the author's experience of Cairo in the years leading up to the 2011 uprisings that led to the end of Hosni Mubarak's rule. Rooney's narrative evinces an active Downtown cosmopolitan spirit characterised by a burgeoning sense of ‘audacity’ in forms of arts activism, and its attendant collective spirit of perseverance that increasingly rendered ineffective the repressive manoeuvres of Egypt's disciplinary State. Criticising the impulse to construe the Egyptian revolution in terms of a mimetic desire for a secular democracy on Western lines, Rooney insists that the Arab uprisings consisted, in many respects, of a revolution against Western-style free market neoliberalism. Countering the perpetual cynicism attendant to the latter, Rooney argues, requires a form of politicisation that maintains ‘the ongoing presence of the real as a matter of collective spirit’ – one that can outlast the colonial interlude by resisting the absolutist self-assertion of market fundamentalism and its collusions with ‘diplo-economic cosmopolitanism’ as a mode of class-discriminatory privilege, as well as the compromising nature of right-wing Islam. Rooney moves on to locate a counter-movement based on an alternative form of consciousness that manifests itself ‘as solidarity, as resoluteness, as genuine comradeship, as collective consciousness, as revolutionary faith and [as] festiveness.’ In the last part of her essay, Rooney raises the intriguing case of Sufism, and specifically its mulid rituals and its important role in the Egyptian revolutionary effort, as a relational cultural mode that can survive the will-to-dominance as a persistent and liberatory collective gesture.


Author(s):  
Joydeep Mazumder ◽  
Devender Pathak ◽  
Rachna Kumria

A lot of herbal plants are used across the globe to remedy various diseases. Herbal treatment is an alternative form for medicine where natural herbs and their extracts are used to cure a situation. Some drugs are proved to contain pharmaceutical ingredients suitable for treatment of stomach acidity or ulcers. The present work deals with the claim that a polyherbal formulation can be formulated which can be used as an alternative to already existing antacid formulations in the market. Therefore, some selected herbs with the tendency to neutralize acid in the stomach are selected and a formulation is formed. Microemulsion of oil showed higher stability with droplet size in the range of 110-410nm. The product then screened for in vitro antacid properties which showed significant positive response


Author(s):  
Сергей Александрович Грязнов

Технологии меняют образ жизни и деятельность человека. Глобальная сеть Интернет облегчает быстрый доступ к полезной информации. Социальная, культурная и образовательная конкурентоспособность находятся под влиянием образовательных технологий, которые положительно влияют на стиль, продолжительность и метод обучения в высших учебных заведениях. Дистанционное образование возможно применять и как полноценную самодостаточную форму, и как дополнение к классическому обучению в аудиториях. Автор рассматривает в статье дистанционную форму обучения как альтернативу традиционной форме преподавания в вузах на время периодов самоизоляции (пандемии, сезонные карантины), а также как дополнение к традиционным формам обучения. Анализируются проблемные и положительные аспекты применения данной формы. Указаны возможные форматы обучения в условиях дистанционного образования. Выделены сильные и слабые стороны использования некоторых технологий. Technologies alter the way of living and work of a person. The Internet world network makes it easier to quickly access useful information. Social, cultural and educational competitiveness are influenced by educational technologies that positively influence the style, duration and method of education in higher education institutions. Distance education can be used as a full-fledged self-sufficient form, or as a Supplement to classical training in classrooms. The author considers distance learning as an alternative to the traditional form of teaching in higher education institutions during periods of self-isolation (pandemics, seasonal quarantines), as well as as an addition to traditional forms of education. The problem and positive aspects of using this form are analyzed. Possible formats of training in the conditions of distance education are specified. The strengths and weaknesses of the use of certain technologies are highlighted.


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