Question: The Oxus cobra contains what kind of ions for their venom to be active? 

Context paragraphs:
Highly charged ion: Highly charged ions (HCI) are ions in very high charge states due to the loss of many or most of their bound electrons by energetic collisions or high-energy photon absorption.  Examples are 13-fold ionized iron, Fe or Fe (XIV) in spectroscopic notation, found in the Sun's corona, or "naked" uranium, U, bare all bound electrons, which requires very high energy for its production.  HCI are found in stellar coronae, in active galactic nuclei, in supernova remnants, and in accretion disks. Most of the visible matter found in the universe consists of highly charged ions .  High temperature plasmas used for nuclear fusion energy research also contain HCI generated by the plasma-wall interaction (see Tokamak).  In the laboratory, HCI are investigated by means of heavy ion particle accelerators and electron beam ion traps.

Ion chromatography: Ion chromatography (or ion-exchange chromatography) is a chromatography process that separates ions and polar molecules based on their affinity to the ion exchanger.  It works on almost any kind of charged molecule—including large proteins, small nucleotides, and amino acids.  The two types of ion chromatography are anion-exchange and cation-exchange.  It is often used in protein purification, water analysis, and quality control.  The water-soluble and charged molecules such as proteins, amino acids, and peptides bind to moieties which are oppositely charged by forming ionic bonds to the insoluble stationary phase.  The equilibrated stationary phase consists of an ionizable functional group where the targeted molecules of a mixture to be separated and quantified can bind while passing through the column—a cationic stationary phase is used to separate anions and an anionic stationary phase is used to separate cations.  Cation exchange chromatography is used when the desired molecules to separate are cations and anion exchange chromatography is used to separate anions.  The bound molecules then can be eluted and collected using an eluant which contains anions and cations by running higher concentration of ions through the column or changing pH of the column.  One of the primary advantages for the use of ion chromatography is only one interaction involved during the separation as opposed to other separation techniques; therefore, ion chromatography may have higher matrix tolerance.  However, there are also disadvantages involved when performing ion-exchange chromatography, such as constant evolution with the technique which leads to the inconsistency from column to column.

Platypus venom: The platypus is one of the few living mammals to produce venom.  Males have a pair of spurs on their hind limbs that secrete venom that is only seasonally active to breeding season, supporting the theory that the use of venom is for competition of mates only, not protection.  While the spur remains available for defense outside of breeding season, the platypus's venom gland lacks secretion.  While the after effects are described as excruciatingly painful, this venom is not lethal to humans.

Envenomation: Envenomation is the process by which venom is injected into some animal by the bite (or sting) of a venomous animal.  Many kinds of animals, including mammals (e.g., the northern short-tailed shrew, "Blarina brevicauda"), reptiles (e.g., the king cobra), spiders (e.g., black widows), and insects (e.g., wasps, honey bees, ants and caterpillars), employ venom for hunting and for self-defense.  Most venoms are administered by biting the skin of the victim, but some venoms are applied externally, especially to sensitive tissues such as those that surround the eyes.  In some reptiles, such as the Gila monster, venom in the saliva enters prey through bites of grooved teeth, but many animals have specialized organs such as hollow teeth (fangs) and tubular stingers that penetrate the prey's skin after which muscles attached to the attacker's venom reservoir forcibly squirt venom deep within the victim's body tissue.  Death may occur as a result of bites or stings.  The rate of envenoming is described as the likelihood of venom successfully entering a system upon bite or sting.

Ribonuclease V1: Ribonuclease V1 (RNase V1) is a ribonuclease enzyme found in the venom of the Caspian cobra ("Naja oxiana").  It cleaves double-stranded RNA in a non-sequence-specific manner, usually requiring a substrate of at least six stacked nucleotides.  Like many ribonucleases, the enzyme requires the presence of magnesium ions for activity.

G.I. Joe: Valor vs. Venom: G.I. Joe: Valor vs. Venom is a direct-to-video CGI animated movie and sequel to "".  It was released in 2004 by Reel FX Creative Studios and distributed by Paramount Home Entertainment.  Like "Spy Troops", the film was written around the theme of the toys released that year.  In this case, it was Valor vs. Venom which introduced a new villain group, Cobra’s V-Troops.

Calsequestrin: Calsequestrin is a calcium-binding protein of the sarcoplasmic reticulum.  The protein helps hold calcium in the cisterna of the sarcoplasmic reticulum after a muscle contraction, even though the concentration of calcium in the sarcoplasmic reticulum is much higher than in the cytosol.  It also helps the sarcoplasmic reticulum store an extraordinarily high amount of calcium ions.  Each molecule of calsequestrin can bind 18 to 50 Ca ions.  Sequence analysis has suggested that calcium is not bound in distinct pockets via EF-hand motifs, but rather via presentation of a charged protein surface.  Two forms of calsequestrin have been identified.  The cardiac form Calsequestrin-2 (CASQ2) is present in cardiac and slow skeletal muscle and the fast skeletal form Calsequestrin-1(CASQ1) is found in fast skeletal muscle.  The release of calsequestrin-bound calcium (through a calcium release channel) triggers muscle contraction.  The active protein is not highly structured, more than 50% of it adopting a random coil conformation.  When calcium binds there is a structural change whereby the alpha-helical content of the protein increases from 3 to 11%.  Both forms of calsequestrin are phosphorylated by casein kinase 2, but the cardiac form is phosphorylated more rapidly and to a higher degree.  Calsequestrin is also secreted in the gut where it deprives bacteria of calcium ions.  .

Philanthotoxin: Philanthotoxins are components of the venom of the Egyptian solitary wasp "Philanthus triangulum", commonly known as the European beewolf.  Philanthotoxins are polyamine toxins, a group of toxins isolated from the venom of wasps and spiders which immediately but reversibly paralyze their prey.  δ-philanthotoxin, also known as PhTX-433, is the most active philanthotoxin that can be refined from the venom.  PhTX-433 functions by blocking excitatory neurotransmitter ion channels, including nicotinic acetylcholine receptors (NAChRs) and ionotropic glutamate receptors (iGluRs).  While the IC values of philanthotoxins varies between analogues and receptor subunit composition, the IC value of PhTX-433 at the iGluR AMPA receptor naturally expressed in locust leg muscle is 18 μm and the IC value at rat nAChRs is 1 μm.

Black-necked spitting cobra: The black-necked spitting cobra ("Naja nigricollis") is a species of spitting cobra found mostly in sub-Saharan Africa.  They are moderately sized snakes that can grow to a length of 1.2 to in length.  Their coloration and markings can vary considerably.  They prey primarily on small rodents.  They possess medically significant venom, although the mortality rate for untreated bites on humans is relatively low (~5–10%, in endemic regions under 1%).  Like other spitting cobras, they can eject venom from their fangs when threatened (one drop over 7 m and more in perfect accuracy).  The neurotoxic venom irritates the skin, causing blisters and inflammation, and can cause permanent blindness if the venom makes contact with the eyes and is not washed off.

Caspian cobra: The Caspian cobra ("Naja oxiana"), also called the Central Asian cobra, Oxus cobra or Russian cobra, a member of the family Elapidae found in Central Asia.

Supporting paragraphs: Ribonuclease V1 Caspian cobra
Answer: magnesium