Archive for September 30, 2014

Types of Oral Appliances in Dentistry

Oral appliances are the devices applied to the patients oral cavity for a certain period of time to treat various disorders associated with the oral cavity. Oral appliances are commonly used to treat sleeping apnea and temporomandibular joint disorders.

Types of oral appliances
There are several types of oral appliances available depending on the type of disorder in oral cavity. These include:

    • Mandibular repositioning devices

Mandibular repositioning devices are made of heat sensitive acrylic material. These are custom fitted to each patient’s mouth. These are used to treat sleeping apnea. Patients with sleeping apnea have narrowed air ways during sleeping. It is fitted to the lower jaw to reposition the mandible to the normal position. This will push the tongue and soft tissue to open the air ways and restore normal breathing during sleeping.

    • Tongue retaining devices

It is used in patients with elongated tongue. It is a device used to keep the tongue in normal position during sleeping. It is used to treat obstructive sleeping apnea syndrome. It is a custom made device made up of soft pliable material. It should be worn while sleeping. It has a compartment in which tongue is positioned by means of negative pressure. Tongue retaining devices require adaptation to the patient holding tongue in the compartment. Therefore tongue exercise and adaption program is given prior to the insertion of tongue retaining device.

    • Orthodontic appliances

Orthodontic appliances are the devices applied to the teeth to position them in normal position. Orthodontic appliances include orthodontic retainers and space maintainers.

    • Orthodontic retainers are custom made orthodontic appliances used to position the teeth in its place after removal of braces. Orthodontic retainers are either fixed or removable retainers.
    • Space maintainers are used to keep the space for the permanent teeth to erupt and come out of the gums. If these are not used the gap created by the missing tooth replaced by the shifting of the adjacent teeth then surgery is necessary to correct the abnormality. These are custom made by the orthodontist and made up of plastic or metallic material. Space retainers are either fixed or removable.

Advantages and Limitations of an Electric Car

Conventional cars emit harmful gases that adversely affect human, animal and plant life. In an endeavor to reduce the harmful effects of pollutants and to conserve the fossil fuels, electric cars came into picture. Electric cars completely depend on electric charge stored in batteries for their power and use electric motors for propulsion. Hence, they are eco-friendly and save fossil fuels. Having so many advantages, electric cars could not become popular in the market mainly because of the limitations imposed by the batteries and few other factors.

Advantages of electric vehiclesWater pump repair

  • Electric vehicles are eco-friendly. This is the biggest advantage of electric vehicles. They do not emit harmful pollutants and do not create noise.
  • They do not rely on fossil fuels for their operation. Hence, you will save a lot of money over fuels as electrical power is relatively cheaper.
  • They require a little maintenance and they can be charged anywhere by docking the vehicle into a power socket.
  • Though the initial investment is little high, they prove to be economical in the long run.
  • Many states and countries offer tax benefits and incentives on purchase of electric vehicles.

Limitations of electric vehicles

  • Electrical vehicles are powered by batteries. The cumulative weight of the batteries is considerable. This in turn affects the performance of the vehicle as the weight has to be bore by the batteries only.
  • Frequent recharging and discharging of the batteries reduces the life of the batteries and they have to be changed over short intervals of time.
  • Their operation time is very less. They are designed to travel a maximum distance of somewhere near 100 km. So, long trips cannot be pursued on these vehicles.
  • Though charging ports are available, these vehicles take 5-6 hours to recharge the battery. Additionally, frequent recharging can reflect on your power bills in a heft way.
  • Service centers are not easily available.
  • The noiseless operation of the vehicles can be a disadvantage since people may not see them coming at blind points and it can pose risk of accidents.

Extensive research is being carried by the manufacturers to reduce the limitations in electric vehicles.
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Treatment Process for Drinking Water

Water is one of the most essential element to life on earth. Without water no living organism can survive. Treatment of drinking water is the process of removal of contaminants from water and make it acceptable for use. The treatment process for drinking water depends on the location, type of water to be processed and the technology of the plant. Here is a standard treatment process for drinking water.

Coagulation
It is the process of removing dirt or other particles from the water. In this process, alum or polymers are added to the water to be treated. This on reaction with water forms a tiny sticky floc. This floc attracts dirt particles in the water and sticks to it and forms a large floc. This process is also called flocculation.

Sedimentation
It is the process where flocs settle down to the bottom. As the water and the flocs pass through the sedimentation basin, water moves slowly to settle down the flocs to the bottom. Flocs which collects to the bottom of the basin is called sludge.

Filtration
It is the process of removing contaminated particles from water. In this step, the water is passed through the filter to remove suspended floc from water. Filters are made up of a layer of sand and gravel or charcoal. Filters used for the removal of particles are slow sand filters, rapid sand filters and membrane filters. This removes even tiny particles present in the water.

Disinfection
It is the process of killing microbes in the water. In this step, disinfectant such as chlorine is added to the water before passing into the distribution system. It is added to kill if any microbes are present in the water. Residual amounts of disinfectants can be maintained to prevent the biological contamination of water in the distribution system.

Sludge drying
It is the process of removal of solids that are collected from the water by sedimentation process to drying lagoons.

Fluoridation
In this process, hexafluorosilicic acid is added to the water which decompose to yield fluoride ions. This fluoride level is adjusted to the optimum level to minimize the dental caries. Excess fluoridation leads to osteoporosis.

PH correction
PH of the drinking water should be 7. Lime is added to the fluoridated water to adjust the PH of the water. It stabilizes the natural soft water to prevent corrosion in distribution system.

Storage
Finally the treated water is stored in closed tanks or reservoirs from where it flows through pipes to homes.
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All about Braking System and Its Components

Brakes are important components in automobiles to control the speed of vehicles. In this article, we will discuss the braking system and their components. Brakes are essential for safety.

About brakes and braking system

  • A brake is a mechanical device that controls motion of an automobile/vehicle by slowing or stopping the moving parts.
  • Braking of a vehicle depends on static function of brakes between tires and road
  • surface.
  • In braking system “The kinetic energy is dissipated in the form of heat energy”.
  • Most brakes use friction between moving parts (wheel or wheel drum) and stationary parts of vehicle (brake shoes).
  • The heat energy generated due to application of brakes is dissipated into air.

Components of braking system in a vehicle
Brake pedal

  • The brake pedal acts as a lever.
  • It’s used to increase the force applied by the driver on the brake pedal pad.
  • It uses a lever to transfer the force from the driver’s foot to the master cylinder.

Brake pads

  • These are the steel plates that are bound with a frictional material facing the rotor. These are mostly used in disc brakes.

Brake lines

  • Brake lines carry the braking fluid from the master cylinder to the brakes.
  • The brake lines transmit a considerable amount of hydraulic pressure to stop the vehicle.
  • These are mostly made of steel and they are attached to the vehicle body with clips to prevent damage from vibration.

Brake shoes

  • These are a pair of steel pieces welded together.
  • A compression spring is placed attached to this shoes so that whenever the brake is applied, the compression spring compresses causing the brake shoes to expand to the brake drum to stop the wheel.

Brake drum

  • It’s a rotating drum-shaped component mounted on the wheel.
  • It is mostly used in drum brakes.
  • The friction between the brake drum and the brake shoes causes the wheel to reduce the speed or stop.

Rotor/brake disc

  • It’s a cast iron material disc which is connected to wheel or axle.
  • With the friction between the brake pads and the brake wheel the motion of the wheel is reduced or stopped.
  • These are also made of reinforced carbon-carbon, and ceramics composite.

Piston

  • It’s a moving component which is connected to the master cylinder.
  • It is used to pressurize the braking fluid.

Caliper

  • The main purpose of the caliper is to slow the vehicles speed by creating friction on the brake disc.
  • The brake caliper fits over the rotor like a clamp.
  • Inside the caliper are a pair of metal plates bonded with friction material called as brake pads.

These caliper are of two types they are as follows

  • Floating caliper
    • It moves relative to the brake disc.
    • It consists of a piston on one side of disc to push inner brake pad into braking surface before pulling caliper body to apply pressure on opposite side of disc.
    • These are also known as a sliding calipers.
  • Fixed caliper
    • It does not move relative to rotor.
    • It uses one or more single pairs of opposing pistons to clamp from each side of the brake disc.

Master cylinder

  • Master cylinder is device which converts the non-hydraulic pressure from your foot into hydraulic pressure.
  • It also controls “slave cylinders” which is at the opposite end of the hydraulic system.
  • It is the most important device pressurizing the braking fluid.

Vacuum servo/brake booster

  • It’s used to enhance the master cylinder and to increases the pressure by driver’s foot by using vacuum in the engine intake.
  • These are effective only when the vehicle’s engine is running.

These are some of the components of the braking system in a vehicle. Proper maintenance of the braking components can prevent brake failure. If you ignore the maintenance of the braking components, it may lead to dangerous accidents.
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Coolant and Its Importance in Vehicles

The coolant plays an important role to protect the engine of your automobile. Without the radiator coolant, your vehicle/car would overheat quickly leading to breakdown and even engine failure. The coolant and water get mixed up in the radiator. This prevents freezing and boiling of the water. In this article, we’ll discuss the coolant and its importance in vehicles.

What does the coolant do?
The coolant is a fluid. It absorbs heat from the engine and then blows it through the radiator. The coolant is also called antifreeze, and is a mixture of ethylene (or propylene glycol) and water, in a 50/50 ratio.

The coolant is a mixture of water and antifreeze. It gets stored in the radiator. Generally, more amount of antifreeze is mixed with water to increase the boiling point and decrease the freezing point. During combustion of fuel, close to 33% of the energy produced will be wasted in the form of surplus heat or exhaust. The excess heat that remains in the engine overheats the engine components which results in its breakdown.

When the coolant mixture moves through the engine by means of a water pump, it circulates through the engine and absorbs the excess heat and takes it to the radiator. Due to the heat exchange process in the radiator, the heat in the coolant is dispelled through the cooling fins, and the coolant is cooled and circulated through the system again. The radiator is placed such that it receives an adequate amount of inflow of outside air consistently to cool the coolant.

Importance of coolant in vehicles
In the absence of the coolant, the heat produced during the internal combustion remains in the engine. Due to the high temperature inside, the motor boils it and destroys the engine very quickly. Due to continuous absorbing heat by the coolant, the water present in the system is likely to evaporate entirely. The water may freeze in cold weather, if the engine is idle. Because of this, the cooling system doesn’t work effectively. Therefore, use of antifreeze is useful to ensure better functionality of the coolant.

You should get the coolant inspected when needed to protect the system’s components against corrosion and overheating.

It is recommended that the coolant should be changed for every 30,000 miles. Even the radiator, should be working well. If rust builds up in the radiator, the heat exchanger may fail leading to problems while you’re driving.

Many mechanical failures are because of overheating of the engine. Ensure that all the cooling system components – the radiator, the water pump, the thermostat and the heater core are in good condition and by keeping the coolant in the system at correct level, you can avoid break down of vehicle.

Making sure to check regularly the coolant in your car reduces the maintenance cost of your car and increases the life of the your engine components.
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