Archive for May, 2014

Lyophilization Its Applications

May 28th, 2014

Lyophilization/freeze drying is a method of extracting the water from Biological samples, foods and other products so that foods or products remain stable and are easier to store and preserved at room temperature. Biological materials should be dried to stabilize them for storage, preservation and shipping. In many cases this drying can cause damage and some loss of cellular or protein activity. Lyophilization significantly reduces damage to biological samples.

Lyophilized/freeze dried products retain their original properties. By adding water or other solvents they can be reconstituted easily and very quickly to a usable solution. For example the Proteins and many other products are presented as a freeze-dried powder in vials for reconstitution by the administering doctor or pharmacy.

Commonly, water is used as solvent, but in some pharmaceutical applications alcohol is used to dissolve or disperse the product.  The freeze dryer itself is a sterile environment, protected by air-sterilizing vent filters.Vent filters also protect the exhaust, and prevent droplets or particles of active ingredients from being carried into the environment.

There is a wide range of substances for which freeze drying/Lyophilization is used as conservation/preservation method without changing their composition. In the aseptic pharmaceutical and biotechnology production, freeze drying/Lyophilization are often applied to the following products:

  • antibiotics,
  • bacteria,
  • vaccines,
  • hormones,
  • vitamins, enzymes, and peptides,
  • liposome and collagen,
  • plants and liver extracts,
  • radio-immuno essays,
  • Blood plasma, plasma fractions, and antibodies.

Process of Lyophilization/freeze drying is recommended for the products whose composition changes on the preservation such as proteins, but in the process of Lyophilization, there is no change in the composition of any substance. Some of applications of this process are;

  • This process provides an efficient technique for preservation of temperature sensitive products, mainly those of biological origin such as proteins, enzymes, blood plasma, vaccines, etc.
  • Lyophilization helps in achieving the chemical balance, such as for biological reagents.
  • Lyophilization is very efficient for the packaging of constituents that cannot be mixed in the liquid state.
  • It helps in improving the storage life and improved marketing of the end product.

It helps in resolving certain filling problems. It may be difficult, for instance, to divide several milligrams of powder into precise vial dosages, due to the difficulty of measuring tiny amounts, homogeneity, granulation, static electricity etc. The distribution of the product from the liquid state eliminates such production problems.


May 23rd, 2014

Lux is a measurement of the overall intensity of light within an environment for any given area or distance from the source or lux is the amount of light in an environments perceived by the human eye. Quality of light in workplace, schools and public buildings affect the quantity and quality of performance in workers and students.

In other words, the lux is a unit of measurement of brightness, or more accurately, illuminance. The illumination is how level of luminous flux is falling on a surface area. The luminous flux is visible component that is defined in radiant flux (light power) divided by relative sensitivity of human eyes over the visible spectrum. This means the Lux is well fit to light level from sense of human eyes. Lux is ultimately derives from the candela, the standard unit of measurement for the power of light.

A candela is a fixed amount, roughly equivalent to the brightness of one candle.While the candela is a unit of energy, it has an equivalent unit known as the lumen, which measures the same light in terms of its perception by the human eye. One lumen is equivalent to the light produced in one direction from a light source rated at one candela. The lux takes into account the surface area over which this light is spread, which affects how bright it appears. One lux equals one lumen of light spread across a surface one square meter.

How to Measure Lighting Levels

Measuring lighting or the illumination of an environment requires the use of an incident Lux meter or foot-candlemeter A lux meter is a device for measuring brightness. It specifically measures the intensity with which the brightness appears to the human eye. This is different than measurements of the actual light energy produced by or reflected from an object or light source.

A lux meter works by using a photo cell to capture light. The meter then converts this light to an electrical current. Measuring this current allows the device to calculate the lux value of the light it captured.

The lux light meter’s calculation of illuminance is done by using the Point Source process.  The measure of the lux light meter varies depending on the light’s intensity and distance.  If a point source has no reflections, a portion of the produced light reaches a surface.

How to measure light intensity using lux light meter

  • Compute for the square of the distance and multiply it by Pi and then by four.  The outcome must be a radius identical to the specific space from the source.  This calculation is the area of sphere at a particular distance.
  • Divide the light concentration in lumens by the spherical area. The product is the illuminance in foot-candles or lux, depending on whether feet or meters were used.
  • Application of a correction factor is needed if the light reaches the surface at an angle less than 90 degrees.  This can be done by multiplying the computed illuminance value by the cosine of the off-axis angle.

Applications of Lux meter

i) Photography and Video Filming. By measuring the light in luxes, photographers can adjust their shutter speed and depth of field to get the best picture quality. The device can also be very useful for filming outdoor scenes of television programs or movies as it allows adjustments to make sure scenes filmed in different light levels have a consistent brightness on screen.

ii) Health and Safety regulations : It can be used to check whether the brightness of a room is enough to meet any rules designed to protect workers from suffering damage to their eyesight. Using a lux meter takes into account the size of the room in a way that simply measuring the intensity of the light source in lumens would not.

iii) Photographic Mesurements; It also measures the photography subject’s illuminance.  When using a lux light meter, the photographer can determine the aperture number and the exposure setting.

Types of Lux Light Meters for the photography

  • Reflected Lux Light Meter

i)         This produces a measurement of the light reflecting from the photography subject to the camera

ii)       This kind of meter is positioned near or in the camera itself

iii)      A type of meter that is commonly installed in camcorders and point-and-shoot camera

iv)     Works best for scenes where light is evenly distributed

v)       May not work for scenes with varying brightness

  • Incident Lux Light Meter

i)         This type of lux light meter must be positioned near the photography subject

ii)       Measures the light intensity falling on the photography subject

iii)      Will produce great light reading when used with light receptor facing the camera

iv)     A photographer may produce trial shots before working on the desired camera settings.

Safety Guideline

  • In case of digital Lux meter, it is necessary to replace battery when the meter shows battery low.
  • The meter should ever not be placed in water deep enough to submerge any part of the upper body of the meter. this will ruin the meter.
  • Do not store the instrument where temperature or humidity is excessively high.
  • The measurement points should not be too close to walls or obstructions
  • Daylight should be shielded by blinds or curtains when assessing artificial lighting only


May 22nd, 2014

Leaf area is an important agronomical parameter as it is related to plant growth, photosynthetic capacity and many times it is used to asses the effect of different plant treatments. Leaf Area Meters are scientific instrument that are specially designed to measure the area of leaves. They are also the morphology analyzer, Diseases and insect damage quantifiers. This instrument is based on Photometric Technology.

Leaf area meter provides leaf area measurement through electronic rectangular approximation this instrument can also be used to measure the area of non-transparent flat surface material like cloth/paper/plastic/leather etc. A leaf area meter provides a non-destructive means for environmental scientists and farmers alike to ascertain plant health, quality and local ecological trends as reflected in the leaf’s area, length, average width and maximum width.

In principle the leaf is placed between a light source and a photocell,the reduction in photocell output due to the presence of the leaf then gives a measure of leaf area. The transmission of light through the leaves is a source of error, and an attempt to minimize this is usually made by fitting a magenta filter between the leaf and the photocell to absorb any green light passing through the leaf.

Leaf area measurement of plants are useful for many scientific disciplines. Monitoring the distribution and changes of leaf area is important for assessing growth and vigour of vegetation on the planet. It is fundamentally important as a parameter in land-surface processes and climate models.

This variable represents the amount of leaf material in ecosystems and controls the links between biosphere and atmosphere through various processes such as photosynthesis, respiration, transpiration and rain interception. A measurement that is seemingly so simple and fundamental is really the backbone that provides the framework for further research in areas like ecology, agronomy, entomology, carbon cycle research and plant pathology. These and many other disciplines rely on the measurement of leaf area in much of their work.