Archive for June, 2014


June 25th, 2014

refractometer measures the extent to which light is bent (i.e. refracted) when it moves from air into a sample and is typically used to determine the index of refraction (aka refractive index or n) of a liquid sample.

The refractive index is commonly determined as part of the characterization of liquid samples, in much the same way that melting points are routinely obtained to characterize solid compounds. It is also commonly used to:

  • Help identify or confirm the identity of a sample by comparing its refractive index to known values.
  • Assess the purity of a sample by comparing its refractive index to the value for the pure substance.
  • Determine the concentration of a solute in a solution by comparing the solution’s refractive index to a standard curve.
  • he speed of light in a vacuum is always the same, but when light moves through any other medium it travels more slowly since it is constantly being absorbed and reemitted by the atoms in the material. The ratio of the speed of light in a vacuum to the speed of light in another substance is defined as the index of refraction (aka refractive index or n) for the substance.


Projection Microscope

June 24th, 2014

A compound light microscope with an added feature of projecting the microscopic image to a wall or projecting screen is called Projection Microscope. Projection microscope is based on the radial propagation of an electron beam from a point source. Projection microscope is interfaced with computer to project the object on wide computer screen for easy analysis. This is the best option for Textile fiber analysis. Any type of measurement like length, area, count of any fine textile fiber can be done. The Projection Microscope is very useful for classroom applications as it projects the image to a wall or computer screen.

Projection microscope forms an extremely enlarged real image of some small objects on a distant screen which can be computer screen. It is different from the viewing microscope in which the viewer observes a virtual image, located in the same plane as the object at a distance of 25 cm from the eye the closest distance of distinct vision.

In both projection and viewing microscopes,

  • The objective lens focuses light from the Object to create a magnified real intermediate image.
  • This image, obtained from the objective lens, serves as an object, or source of light, for the second lens.
  • This second lens can be eyepiece in the viewing microscope or a projecting lens in the projecting microscope.

A viewing microscope can be converted to a projecting microscope by increasing the separation of the two lenses named objective lens and eyepiece, as the first principal focus of the eyepiece lens lies to the right of image obtained from objective piece in the projector, whereas second principal focus is to the left of image obtained from objective lens in the viewing microscope.

In general in the projection microscope, the first lens of the microscope, the objective lens, creates a magnified real image of our object. This intermediate image serves as the object or basis for the second lens of the microscope, the projector lens through which the image projects on computer screen.

Plant Growth Chambers

June 23rd, 2014

Plant Growth Chambers an approach to study the factors affecting the Plant growth

 is the process by which a plant increases in the number and size of leaves and stems. The growth of both plants and animals requires energy. Animals get their energy by digesting the plants they eat. Plants get their energy from the sun through photosynthesis.

Photosynthesis is the process where the green pigment in the plant’s leaf (chlorophyll) absorbs energy from sunlight and, using this energy, water, and carbon dioxide, produces oxygen and simple sugars. The plant then uses these sugars to make more complex sugars and starches for storage as energy reserves, to make cellulose and hemicellulose for cell walls or with nitrogen, to make proteins. How the plant uses its energy depends on the developmental stage of the plant and on environmental conditions.

Growth is determined by environmental factors, such as temperature, available water, available light, and available nutrients in the soil. Any change in the availability of these external conditions will be reflected in the plants growth. Biotic factors (living organisms) also affect plant growth.

Plant growth and geographic distribution are greatly affected by the environment. If any environmental factor is less than ideal, it limits a plant’s growth and/or distribution. For example, only plants adapted to limited amounts of water can live in deserts.

Either directly or indirectly, most plant problems are caused by environmental stress. In some cases, poor environmental conditions (e.g., too little water) damage a plant directly. In other cases, environmental stress weakens a plant and makes it more susceptible to disease or insect attack.

Environmental factors that affect plant growth include

  • Temperature; is a measure of the intensity of heat. Plant growth occurs in a fairly narrow range – 60 – 100 degrees F. Temperature directly affects the processes of photosynthesis, respiration transpiration  and absorption of water and nutrients.
  • Moisture supply; Plant growth is restricted by low and high levels of soil moisture as good soil moisture improves nutrient uptake. If moisture is a limiting factor fertilizer is not used efficiently.
  • Radiant energy; quality, intensity and duration (photoperiodism) of light are important for the plant growth. Photoperiodism is defined as the behavior of plant in relation to length of the day. On the basis of day period the plants can be:

a)      long day plants – flowering occur only if days are longer than same critical period – 12 hours e.g. Grains and clovers

b)      Short day plants – flowering occur only if days are shorter than critical period e.g. soybeans.

c)       Indeterminate – flowering occur over a wide range of day lengths. E.g. Tomato, cotton, buckwheat

  • Composition of the atmosphere; plant growth majorly depends on the amounts of gases present in the atmosphere such as carbon dioxide, nitrogen etc.
  • Soil aeration and soil structure; Compact soils of high bulk density and poor structure are aerated poorly. Pore space is occupied by air and water so the amount of air and water are inversely proportional to the amount of oxygen in the soil. On well drained soils, oxygen content is not likely to be limiting to plant growth.

There are many more environmental factors affecting plant growth some of them are:

  • Soil reaction
  • Biotic factors
  • Supply of mineral nutrients
  • Absence of growth-restricting substances

It is important to understand how these factors affect plant growth and development.

With a basic understanding of these factors, one (researcher/student) may be able to manipulate plants to meet required needs, whether for increased leaf, flower, or fruit production. By recognizing the roles of these factors, personnel also will be better able to diagnose plant problems caused by environmental stress.

Environmental chambers called Plant growth chambers are designed to study the effect of described different environmental factors such as humidity, temperature and light in various application tests. These plant growth chambers can be Rich in chambers or walk in chambers.

These plant growth chambers have their applications in the following areas;

  • Production of biotherapeutic proteins
  • Germplasm containments
  • Biotechnology
  • Agriculture
  • Tissue Culture Applications
  • Enzyme reaction applications
  • Fermentation analysis