Beryllium

  BERYLLIUM

Symbol --- Be

Abundance --- 0.00019% in earth's crust.

Physical state --- solid

Elemental Category --- Alkaline earth metal

Colour --- white-gray

Discovery --- Louis Nicolas Vauquelin (1798)

Atomic no --- 4

Atomic weight --- 9.012

Period --- 2

Group --- 2

Block --- s-block

Known Isotopes--- ₄Be⁷ ₄Be⁹ ₄Be¹⁰

Stable Isotopes --- ₄Be⁹ 

Isotopic abundance --- ₄Be⁹ (100%)

Melting Point --- 1560 K (1287⁰C)

Boiling Point --- 2742 K (2469⁰C)

Density --- 1.84 g/cc

Electron Configuration --- [He] 2s²

Oxidation State --- +2

Valence --- 2

Electronegativity --- 1.57

Ionisation Energy --- 900 KJ/mol (1st), 1757 KJ/mol (2nd), 14840 KJ/mol (3rd)

Covalent Radius --- 96 pm

Van der Waals radius --- 153 pm

Crystal Structure --- hcp (hexagonal close packed) 

Heat of fusion --- 12.1 KJ/mol

Heat of vaporisation --- 293 KJ/mol

Molar heat capacity --- 16.45 J/mol-K

Specific heat --- 1820 J/(Kg-K)

Thermal conductivity --- 195 W/(m k) 

Molar volume --- 0.00000487

Speed of sound --- 12895 m/s

Magnetic type --- diamagnetic

Mass magnetic susceptibility ---   -1.26x10^-8 m³/kg

Molar magnetic susceptibility --- - 1.136 x 10^-10 m³/mol 

Lattice angles --- π/2, π/2, π/3

Lattice constants --- 228 pm,228 pm,358 pm

Quantum numbers --- ¹S₀

Neutron cross section --- 0.009

Electrical conductivity --- 2.5 x 10⁷ S/m

Electrical resistivity --- 36 nΩ m

Mohs hardness --- 5.5

Brinell hardness --- 595 MPa

Young's modulus --- 287 GPa

Bulk modulus --- 130 GPa

Shear modulus --- 132 GPa

Poisson ratio --- 0.032

Vickers hardness --- 1670 MPa

Beryllium is of very rare abundance in the universe, it is produced as a product of the spallation reaction. When a larger atomic nucleus collided with cosmic ray’s spallation reaction occur, as a result of this reaction beryllium is produced. Beryllium is of very low abundance in the earth’s crust. The major ores of beryllium are beryl Be₃Al₂(SiO₃)₆ and phenacite Be₂SiO₄. Beryllium is extracted from these ore. Beryllium is the second lightest metal after lithium and quite hard and brittle in nature. Beryllium is used for windows material in X-ray tubes and it is largely used to improve the properties of Cu and Ni alloys. In the nuclear reactor beryllium is used as moderator and also used in electronic industries.

ABOUT BERYLLIUM

NANOBOTS or NANOROBOTS

For the applications of nanotechnology, a very fast growing and promising field is in the practice of medicine. Application of nanotechnology in the medicinal field is often referred to as nanomedicine. In the medicinal field nanotechnology is applied by the creation of nanoscale devices for improved therapy and diagnostics. This nanoscale devices are often referred to as nanorobots or more simply nanobots. For delivery of therapeutic agents, detectors or guardians against early disease these nanobots have the capability to serve as delivery vehicles also they have the capability to repair of metabolic or genetic defects. These nanobots would be programmed to perform specific function like to the conventional or macroscopic robots, and also these nanobots controlled by remote. The size of these nanobots is in nanoscale, so they can travel and performed desired functions inside the human body.

In the human body when nanobots are applied to medicine, these nanobots are capable to find the target within the body such as an invading virus or cancer cell, therefore these nanobots perform some function to fix the target. Since nanobots is controlled by remote, they have the capacity to releasing a drug in the appropriate target or in a localized area, so they minimized the potential side effects of generalized drug therapy. Nanobots may bind to a target and prevent the target from further activity, thus for example, preventing a virus from infecting a cell. Since nanotechnology is developing, it is possible in near future, gene replacement, tissue regeneration or nano surgery by nanobots.

Since nanobots is used as a delivery vehicle or carrier, so they carry payload. Three types of nano material used for this purpose to carry payload such as carbonnanotubes or buckyballs, various dendrimers, various nanoparticle or nanocrystals.

Nanobots find the target in the human body and repair the target. This mechanism is based on antigen or antibody interactions or binding of target molecules to membrane-bound receptors.

Through the natural mechanisms of metabolism and excretion most of the nanobots or nanodevices could be eliminated from the human body after performing their work. Nanobots made by biodegradable or naturally occurring substances, such as calcium phosphate would be a favorable approach, because they are eliminated from the human body naturally after performing the desire function.

The negative impact of using nanobots is that if they cause pollution and clog of system in human body. Another problem is that if nanobots may become out of control due to lost of some function in nanobots or nanobots malfunction.     

 MERCURIAL DIURETICS

In the sixteenth century Paracelsus used calomel as a diuretic. In the year 1919 antisyphilitic agent, merbaphen, was tested for its diuretic action. In the mercurial diuretics Hg²⁺ is essentially present in the organic molecule. The general structure of most mercurial diuretics contains a chain of at least three carbon atoms and one mercury atom. The general structure of mercurial diuretics is as follows---

Y―CH₂―CH(OCH₃) ―CH₂―Hg―X

Where,

X = Halide, OH, heterocyclic compound

Y = substituted side chain, substituted aromatic compound.

The Y group that is substituted side chain or substituted aromatic compound is hydrophilic in nature, which determines the distribution and rate of excretion of the compound. Whereas the X group that is halide or OH or heterocyclic compound affects the toxicity of the mercurial diuretics compound, irritation at the site of injection, and rate of absorption. The mercuric ion (Hg²⁺) of the mercurial diuretics dissociates and binds to the sulfhydryl enzymes and inactivating them in an acidic environment. Due to this reabsorption of sodium ion (Na⁺) is diminished and increased the excretion of sodium ion (Na⁺) and chloride ion (Cl^-). More Cl^- ion is lost than Na⁺ ion. As a result, cations such as hydrogen ion (H⁺) and lesser degree of potassium ion (K⁺) are also lost to maintain the electrical neutrality. Due to excess excretion of chloride ion (Cl^-), bicarbonate (HCO₃^2-) remains to maintain balanced anions, and the resulting picture is a hypochloremic alkalosis. Mercurial diuretics usually inhibit active chloride transport in the ascending limb of the loop of Henle.

The mercurial diuretics are now of limited use due to their pronounced and marked side effects such as renal tubular damage, mercurialism, hypersensitivity and excessive diuresis which may led to electrolyte depletion and vascular complications. Most of the mercurial diuretics are administered by intramuscular route. Some examples of mercurial diuretics are chlormerodrin, mercaptomerin sodium, meralluride, merethoxylline procaine, mercumatilin sodium etc.

Synthesis of Chlormerodrin

It is prepared by the reaction of N-allyl urea with mercuric acetate in presence of methanol, as a result 2-methoxy-N-propyl urea is formed. When 2-methoxy-N-propyl urea react with NaCl chlormerodrin is produced.

Synthesis of Mercaptomerin Sodium

Camphoric acid on reaction with ammonia in the presence of allyl isocyanate formed an intermediate, which on treatment with mercuric acetate in presence of methanol gives mercury derivative as acetate, which on reaction with sodium thioglycolate in presence of sodium chloride and aqueous sodium hydroxide produced mercaptomerin sodium.