Category Science

Growing annuals, perennials and bulbs

  •  Film protection for seeds

If you’ve just sown flower seeds in a seedbed and are pleased with the spacing and soil coverage, you can go one extra step towards warming the soil and speeding germination, and keeping the earth moist and thwarting birds foraging for seeds. All it takes is spreading a layer of clear plastic wrap over the seeded area. Anchor the plastic with rocks and remove it as soon as the seeds have sprouted.

  •  A salt that flowers crave

Epsom salts consist of magnesium sulphate, which, as a supplement to your plants’ regular feedings, will deepen the colour of blooms and help to fight disease. Every three or four weeks, scratch 1 teaspoon Epsom salts into the soil around an annual or perennial’s stem and water well. Alternately, dissolve 1 tablespoon Epsom salts in 3.5 litres water. Every two weeks or so, pour some of the solution into a spray bottle and spray the leaves of your flowers.

  •  Prop up tall perennials

Peonies, delphiniums and gladiolus are among a number of tall perennials that generally need support. A wooden stake is the usual answer, but a less obtrusive option is a tall, old lampshade frame. Place the metal frame, narrow side down, amid seedlings when they’re about 15cm tall, working the frame into the soil to a depth of about a centimetre. As the seedlings grow, tie them loosely to the top of the frame with twist ties. The leaves will obscure the frame as the blooms above stand tall.

  •  Bromeliads like fruit

To encourage a potted bromeliad’s rosette of leaves to sprout its pretty flower, place the plant in a plastic dry-cleaning bag with a ripening banana or three or four ripe apples. The ethylene emitted from the fruit will stimulate flower production.

  • Splints for bent stems

If any of your flower stems are bent, pick one of these common items to use as a splint: for thin stems, a toothpick or cotton bud; for thicker stems, a drinking straw, pencil, ballpoint pen or paddle-pop stick. Fix the splints to stems with clear tape, but not too tightly.

  •  Ties for stakes

‘Ropes’ made from old pantihose have long been used to tie snapdragons, hollyhocks, tomatoes and other tall flowers and climbing vegetables to stakes (they’re soft and pliable), but pantihose aren’t the only household item that will serve the purpose. Try these ties:

  1. Gift-wrapping ribbon left over from birthday parties
  2.  Broken cassette tapes
  3.  Plastic garbage bag ties
  4.  Dental floss (the thicker kind)
  5.  Velcro strips
  6.  Fabric strips cut from old sheets
  7.  Strips of hessian or sacking material
  •  Make a flower dome

 Get creative and use an old umbrella — stripped of both its handle and fabric — as a frame for a flowering climber or vine. In the spot of your choice, drive a 1.5-m metal pipe wide enough to accommodate the handle into the ground about 30cm deep, then slide the umbrella stern inside. Plant seedlings of morning glory or any other thin-stemmed flowering vine next to the pipe. Over the next few weeks a unique garden focal point will take shape.

  •  Make hand cleaning easier

 If your garden gloves have gone missing but you need to work in the soil of your flowerbeds, just scrape your fingernails over a bar of soap before you start doing the messy work. The dirt will come out from under your nails more easily when you scrub your hands.

  •  Bag bulbs to prevent rot

Brown paper bags filled with sawdust or coconut fibre peat are the easy answer to the winter storage of tender crocus, tulip, daffodil, iris and other bulbs and rhizomes. Put a 5-cm layer of sawdust or peat in the bottom of the bag and then arrange bulbs of the same type on top, making sure that they don’t touch. Continue layering the bulbs and organic material until the bag is about three-quarters full. Clip the bag closed with clothes pegs or bulldog clips and use a marker to label each bag with the name of the bulbs contained inside.

  •  Plastic bulb protectors

To keep underground pests from burrowing and nibbling on newly transplanted bulbs, seal the bulbs off in wide-topped plastic containers. Before planting, punch drainage holes into the bottom and sides of a large plastic bottle or carton, bury it in the soil up to the open top and fill it with soil and humus. Plant two or three small bulbs in the container or one or two larger bulbs. This won’t stop rats or mice from attacking your bulbs, but it will protect them against burrowing pests.

Old plastic storage boxes are more space-efficient — and you may find other kinds of potential bulb protectors if you go rummaging through your garage or shed.

  •  Flavour food with scented geraniums

Scented geraniums have edible leaves that release a fragrance when rubbed. Among the varieties to grow in pots (or, in warmer climate areas, flowerbeds) are those with the aroma of rose, lemon, apple, apricot, lime, coconut, cinnamon, ginger, mint or nutmeg. Foods that benefit from the addition of finely chopped scented geranium leaves include fruit compotes, biscuits, cakes and poached pears.

Credit: Reader’s Digest

Picture Credit: Google

Caring for trees and shrubs

  •  Newspaper protection for young trees

If you have planted out tree saplings that look a bit spindly, wrap the trunks in newspaper to protect them from the elements. Secure this newspaper sleeve with garden twine. Or make a foil sleeve, to prevent rabbit damage. Remove the newspaper or foil within a month to prevent insects from collecting inside the sleeve.

  •  Lichens: love them or hate them?

Lichens are the ruffled, fungus-like organisms that grow on stones, brick walls and tree trunks. Many gardeners love the natural look that lichens lend to trees and paths — but if you’re not among them, this is a simple way to make lichens disappear: scrub them with a stiff brush dipped in a solution of 2 tablespoons household bleach and 1 litre water. Be very careful that none of the run-off comes into contact with other garden plants.

  •  Warm sleeve for standard stem roses

Standard roses are ordinary rosebushes grafted onto long rootstock trunks. To protect the graft in cold winter areas, cut the sleeve off an old jumper or sweatshirt. Prune back the bush’s top growth in late autumn, then slit the sleeve and wrap it around the graft scar, tying it at top and bottom. Stuff the sleeve with coconut fibre peat or clean straw for insulation, then tie a split plastic bag around the stuffed sleeve for protection against severe frost. When you remove the sleeve in spring, your rose should grow more vigorously.

  •  Speed rose-blooming with foil

 In mid-spring, place sheets of aluminium foil on the ground beneath your rosebushes and anchor the foil with stones. Sunlight reflecting off the foil will speed up blooming.

  •  Feed bananas to roses

Most gardeners know that banana skins make a good fertilizer for tomatoes, peppers and their solanaceous cousins, but roses love them, too. Chop banana skins (up to three) into small pieces and dig them into the soil beneath a rosebush. The banana skins provide both phosphorus and potassium — important plant nutrients that spur the growth of sturdier stems and prettier blooms.

  •  A grassy boost for azaleas

After mowing the lawn, lay some of the grass clippings out to dry. Then spread a thin layer of clippings around the base of azalea plants. As the grass decays it leaches nitrogen into the soil, supplementing regular feeds. Many gardeners find this ‘something extra’ speeds the growth of azaleas and darkens the leaves. Be careful, though: piling the grass clippings too thickly may make them slimy and, in turn, expose the plant’s stems to disease.

  •  Cola and tea for gardenias and azaleas

Occasionally watering a gardenia or azalea bush with a can of cola will increase the acidity of the soil, while the sugar will feed micro-organisms and help organic matter to break down. And tea? Place tea bags around the base of a gardenia or azalea plant and then cover with mulch. Whenever you water the plants, the ascorbic acid, manganese and potassium present in the tea leaves will trickle down to the shrubs’ hungry roots.

  •  Cleaning sap off pruning tools

Taking a saw or shears to tree branches usually leaves sticky sap on the tool. Use a clean cloth to rub any of the following substances onto the blade(s), and say ‘goodbye’ to sap:

  1.  Nail polish remover
  2.  Baby oil
  3.   Olive oil cooking spray
  4.  Suntan oil
  5.  Margarine
  •  Lubricate pruning shears

Rubbing petroleum jelly or spraying WD-40 onto the pivot joint of a pair of shears will have you snipping away at shrubs so smoothly that you will feel like a professional pruner.

Credit: Reader’s Digest

Picture Credit: Google

Who built the first flying helicopter and when?

Although the helicopter in its present form is scarcely 50 years old, the principle of the rotary wing has been known for centuries. The Chinese used it some 2500 years ago for their flying top — a stick with propeller-like blades on top which was spun into the air. And Leonardo da Vinci actually sketched a helicopter in 1483. The English flight pioneer Sir George Cayley was among several people to design a model helicopter in the late 1700s, but the first man-carrying helicopter, which rose a few feet in the air, was not built until 1907 — by a Frenchman, Paul Cornu, at Lisieux. Problems with stability and other design aspects led to helicopters being abandoned for nearly 30 years in favour of fixed-wing aircraft. Many of the design problems were, however, solved by the Spanish inventor of the autogiro, Don Juan de la Cierva, in 1919. This aircraft had a large rotor that was not driven by the engine but turned freely in the airflow. It could not take off vertically — it had to taxi to get the rotor turning enough to lift it.

Not until 1936 did the German Professor Heinrich Focke, of the Focke-Wulf Company, design a practical helicopter with twin rotors. Three years later a Russian-born engineer, Igor Sikorsky, produced a successful single-rotor helicopter, the VS-300, in the USA. This was the true ancestor of the modern rotorcraft — the most versatile of aircraft.

The development of jet engines in the 1950s led to the adoption of turboshaft engines that have considerably increased the range and speeds possible. Today the helicopter is invaluable not only as a military transport, hedge-hopping patrol plane and sky crane — for lifting steeples onto churches, for example — but also for rescuing people from remote mountainsides, sinking ships and burning buildings.

 

Picture Credit : Google

How does a submarine’s crew navigate underwater?

Submarines often travel in the ocean depths for weeks on end. They do not need to surface to check their position by the Sun, Moon or stars, because the latest navigation systems allow them to know where they are to within less than 320ft (100m) of their actual position while still submerged.

 These systems are known as inertial navigation systems and are computer-controlled. There are usually at least two on a submarine, operating independently. They are a modern version of ‘dead reckoning’ — calculating where you are by measuring exactly how far you have come from your starting point, and in what direction.

The inertial navigation system is held absolutely horizontal and pointing in a fixed direction by gyroscopes, whatever the attitude of the submarine.

 At the start of the voyage, the instruments are fed with the submarine’s exact position. An accelerometer then measures movement in every direction, and the computer works out the overall distance and direction travelled, thus establishing the present position.

Sonar is used to determine the water depth below the vessel to prevent it running aground. Inertial systems are on the whole accurate, but the small errors they do make gradually accumulate. They have to be realigned regularly. This is done by picking up radio signals from satellites in space, which form part of the American NAV-STAR Global Positioning System (GPS). The submarine has to partly surface.

 The satellites transmit a radio message which contains precise details about their orbit, and a time signal controlled by an atomic clock. In effect, the signal says ‘It is now time X’. The submarine uses its own clock to calculate how long it takes the signal to arrive. As radio waves travel at 186,000 miles (300,000km) per second, the navigators can calculate the sub-marine’s distance from the satellite by the time the signal takes. By calculating the distance from three GPS satellites, the ship’s position can be pinpointed on a chart.

During the 1990s, the last 04 18 satellites in the GPS system will be placed in orbit at a height of 12,500 miles ,20.000km), orbiting the Earth at 12-hourly intervals. They will ensure that at any time at least four satellites will be available for navigators to calculate their position to within 550yds (500m;

The GPS system has virtually replaced older forms of submarine navigation such as the OMEGA system, but submarines still carry it as a back-up. This system detects radio signals broadcast from eight stations dotted around the Earth’s surface — in Japan. Hawaii, Australia, Argentina, North Dakota. Norway. Liberia and Reunion Island. These stations broadcast at very long wavelengths, so their signals carry all around the world. The signals are synchronised, and by measuring the time differences in their reception, a sub-marine’s position can be estimated to within about miles (3.2km)

 Inertial navigation also mounted in long-range intercontinental launched from submarines .

 

Picture Credit : Google

How do hidden defences detect burglars?

Medieval castles had all sorts of traps pitfalls to keep out intruders. Homes of today can have an equal number of defences, without having to resort boiling pitch. Modern defence devices include floodlights or alarms that are triggered when an intruder upsets a circuit monitored by hidden magnets or micro. chips, or by invisible beams.

The outer defences

The modern burglar might first have to face  a strategically placed invisible infrared detector that is affected by temperature changes caused by body heat. When anyone approaches the house, a sensor in When the detector switches on floodlights. If the caller is legitimate, the lights show the Way but anyone planning burglary will feel very exposed and less likely to continue.

The sensor is pyroelectric — that is, made from a ceramic material such as tourmaline, which, when heated, generates a voltage across it. The system is designed so that the sensor will respond to a temperature change caused by human body heat, but is less likely to be set off by changes in the weather.

 A burglar who dodges a floodlight – barrier may then face a door connected to a noisy alarm. A magnetic switch IL inserted between the door and its frame. When the door is shut, two contacts keep switch circuit closed. This switch is monitored electronically by an alarm circuit. If the door is opened arid switch circuit is broken, the alarm circuit triggers the alarm.

But a resolute burglar, out of sight of passers-by, might attack the door with a chisel or drill. This type of attack can be foiled by a vibration detector fitted to the door. This is a device in which a ball is disturbed by vibrations. The ball rests on sharp metal points wired to a microchip that is programmed to accept certain vibrations — such as those caused by wind or passing traffic — as normal. If the ball bouncing on the points sets up vibrations not in the program, it sets off the alarm.

The inner defences

If the burglar succeeds in getting through a door or window, he may face a battery of inner defences. These include pressure Dads concealed under the carpet and inked to an alarm circuit. They have two metal plates or foil sheets separated by a layer of spongy plastic. The two plates are pressed together if anyone treads on them, and this sets off the alarm.

Anyone who prowls around inside the house may be caught by a ‘magic eye’. This is a photoelectric cell with an invisible infrared beam shining onto it. If the beam is interrupted, the photocell triggers an alarm.

Other types of indoor detector use either ultrasonic waves (too high pitched for humans to hear) or microwaves (high-frequency radio waves) transmitted by

devices called transducers. They transmit the waves at a certain frequency (a given number per second), and the waves are reflected back to the unit from objects in the room. If anyone moves through the room, the reflected waves get bunched up or pulled apart, so their frequency is altered. The sensor detects the frequency change and feeds signals to a microchip which assesses the speed and bulk of the intruder. Anything assessed as typically man-sized makes it set off the alarm.

A commoner type of indoor detector uses an infrared system similar to the outdoor floodlight type. in the detector. a many-faced mirror or special lens creates a number of sensitive zones. If anything moving in and out of these zones is at a different temperature to the room surroundings, it generates a voltage. The detector electronically monitors the voltage, and is designed to set off the alarm if the temperature increase is likely to be caused by human body heat.

 

Picture Credit : Google

How can metals be made to remember shapes?

When lightning struck the roof of York Minster, one of Britain’s finest medieval cathedrals, in 1984, it started a fire that was if trapped between the ceiling and the wooden roof. Firefighters could not get into the area, and the enormous heat that built up destroyed most of the roof.

If lightning should strike York Minster twice, space-age science has ensured that the same type of damage will not happen again. The new roof is fitted with trap doors to let the heat out and the firefighters in, and the doors have latches operated by springs made from memory metals, which will open automatically if they get hot.

Memory metals have two different shapes they can ‘remember’, and will switch from one to the other under certain conditions. The York Minster trap-door springs are made to remember a certain temperature, at which they will expand and withdraw the bolt, releasing the door.

One of the first uses of memory metals has been for hydraulic pipe couplings in aircraft, which came into use in 1971. The couplings are made too small to fit at a certain temperature, and are then cooled to well below room temperature and stretched to fit. When they warm up to their normal operating temperature, they shrink to the first shape, forming a tight joint. The same idea is used in surgery, with metal couplings to bind together broken bones. Body heat keeps them constantly tight.

Metals that change their shape under heat now have all kinds of uses, such as operating switches and valves in automatic coffee machines, and opening greenhouse windows when it is hot and closing them when it is cold. Most metals are made up of crystals (arrangements of atoms). When two or more metals are combined into an alloy, the alloy can form different crystal structures under different conditions.

Some alloys, if they are cooled rapidly, will undergo an abrupt change to a different alignment of crystals at a certain temperature. This transition temperature varies with the make-up of the alloy. The changed structure it brings about is called martensite, after the German metallurgist Adolph Martens who first identified it.

If such an alloy is shaped by heat treatment so that it becomes martensite at, for example, 122°F (50°C), it will change its shape at that martensitic temperature, but revert again at a different temperature.

Shaped for shaping

A Japanese company has found an unusual use for memory metals — as a super-elastic wire frame in brassieres. The alloys used will stretch up to ten times more than ordinary metals. When stretched in use, the bra wire gradually returns to its original bust-supporting shape.

Another use for super-elastic wire is in straightening teeth. Conventional stain-less-steel wires have to be regularly tightened, often by turning a tiny key. Super-elastic alloy wires exert a continuous gentle pressure ideal for coaxing teeth in the right direction.

 

Picture Credit : Google