Paramethoxymethamphetamine (PMMA), is a stimulant drug related to PMA.
PMMA reputedly produces similar effects to PMA, but is apparently slightly more similar to MDMA in effects [1][2] and has slightly less tendency to produce severe hyperthermia, at least at low doses. At higher doses however the side effects and danger of death are just as severe as those of PMA itself,[3] and PMMA should be considered a dangerous drug similar to its parent compound.
PMMA is a lesser-known psychedelic drug. It is the 4-methoxy analog of methamphetamine. PMMA was probably first synthesized by Alexander Shulgin. In his book PiHKAL (Phenethylamines i Have Known And Loved), the minimum dosage is listed as 100mg, and the duration unknown. Shulgin reported that Methyl-MA produces an increase in blood pressure and in heart rate, but causes no psychoactive effects, however user reports following the subsequent appearance of this drug on the illicit market as an analogue of "Ecstasy" (MDMA) suggest that PMMA does produce some empathogenic effects. Very little data exists about the pharmacological properties, metabolism, and toxicity of PMMA, and given the known toxicity of the related compound PMA it is likely to have considerable potential to cause harmful side effects or overdose which can be fatal.[4]
Constituent atoms or molecules of paramagnetic materials have permanent magnetic moments (dipoles), even in the absence of an applied field. This generally occurs due to the spin of unpaired electrons in the atomic/molecular electron orbitals (see Magnetic moment). In pure paramagnetism, the dipoles do not interact with one another and are randomly oriented in the absence of an external field due to thermal agitation, resulting in zero net magnetic moment. When a magnetic field is applied, the dipoles will tend to align with the applied field, resulting in a net magnetic moment in the direction of the applied field. In the classical description, this alignment can be understood to occur due to a torque being provided on the magnetic moments by an applied field, which tries to align the dipoles parallel to the applied field. However, the truer origins of the alignment can only be understood via the quantum-mechanical properties of spin and angular momentum.
If there is sufficient energy exchange between neighbouring dipoles they will interact, and may spontaneously align or anti-align and form magnetic domains, resulting in ferromagnetism (permanent magnets) or antiferromagnetism, respectively. Paramagnetic behavior can also be observed in ferromagnetic materials that are above their Curie temperature, and in antiferromagnets above their Néel temperature. At these temperatures the available thermal energy simply overcomes the interaction energy between the spins.
In general paramagnetic effects are quite small: the magnetic susceptibility is of the order of 10−3 to 10−5 for most paramagnets, but may be as high as 10-1 for synthetic paramagnets such as ferrofluids.
| Material | χm=Km-1 x 10-5 |
|---|---|
| Tungsten | 6.8 |
| Cesium | 5.1 |
| Aluminium | 2.2 |
| Lithium | 1.4 |
| Magnesium | 1.2 |
| Sodium | 0.72 |
In many metallic materials the electrons are itinerant, i.e. they travel through the solid more or less as an electron gas. This is the result of very strong interactions (overlap) between the wave functions of neighboring atoms in the extended lattice structure. The wave functions of the valence electrons thus form a band with equal numbers of spins up and down. When exposed to an external field only those electrons close to the Fermi level will respond and a small surplus of one type of spins will result. This effect is a weak form of paramagnetism known as Pauli-paramagnetism. The effect always competes with a diamagnetic response of opposite sign due to all the core electrons of the atoms. Stronger forms of magnetism usually require localized rather than itinerant electrons. However in some cases a bandstructure can result in which there are two delocalized subbands with states of opposite spins that have different energies. If one subband is preferentially filled over the other, one can have itinerant ferromagnetic order. This usually only happens in relatively narrow (d-)bands, which are poorly delocalized.
In general one can say that strong delocalization in a solid due to large overlap with neighboring wave functions tends to lead to pairing of spins (quenching) and thus weak magnetism. This is why s- and p-type metals are typically either Pauli-paramagnetic or as in the case of gold even diamagnetic. In the latter case the diamagnetic contribution from the closed shell inner electrons simply wins from the weak paramagnetic term of the almost free electrons.
Stronger magnetic effects are typically only observed when d- or f-electrons are involved. Particularly the latter are usually strongly localized. Moreover the size of the magnetic moment on a lanthanide atom can be quite large as it can carry up to 7 unpaired electrons. This is one reason why superstrong magnets are typically based on lanthanide elements like neodymium or samarium.
Of course the above picture is a generalization as it pertains to materials with an extended lattice rather than a molecular structure. Molecular structure can also lead to localization of electrons. Although there are usually energetic reasons why a molecular structure results such that it does not exhibit partly filled orbitals (i.e. unpaired spins), some non-closed shell moieties do occur in nature. Molecular oxygen is a good example. Even in the frozen solid it contains di-radical molecules resulting in paramagnetic behavior. The unpaired spins reside in orbitals derived from oxygen p wave functions, but the overlap is limited to the one neighbor in the O2 molecules. The distances to other oxygen atoms in the lattice remain too large to lead to delocalization and the magnetic moments remain unpaired.
For low levels of magnetization, the magnetisation of paramagnets follows Curie's law to good approximation:
where
This law indicates that the susceptibility χ of paramagnetic materials is inversely proportional to their temperature. Curie's law is valid under the commonly encountered conditions of low magnetisation (μBH ≲ kBT), but does not apply in the high-field/low-temperature regime where saturation of magnetisation occurs (μBH ≳ kBT) and magnetic dipoles are all aligned with the applied field. When the dipoles are aligned, increasing the external field will not increase the total magnetisation since there can be no further alignment.
For a paramagnetic ion with noninteracting magnetic moments with angular momentum J, the Curie constant is related the individual ions' magnetic moments,
C=\frac{N_{A}}{3k_{B}}\mu _{\mathrm{eff}}^{2}\text{ where }\mu _{\mathrm{eff}}=g_{J}\sqrt{J(J+1)}\mu _{B}.
The parameter μeff is interpreted as the effective magnetic moment per paramagnetic ion. If one uses a classical treatment with molecular magnetic moments represented as discrete magnetic dipoles, μ, a Curie Law expression of the same form will emerge with μ appearing in place of μeff.
!Click "show" to see a derivation of this law: |- |Curie's Law can be derived by considering a substance with noninteracting magnetic moments with angular momentum J. If orbital contributions to the magnetic moment are negligible (a common case), then in what follows J = S. If we apply a magnetic field along what we choose to call the z-axis, the energy levels of each paramagnetic center will experience Zeeman splitting of its energy levels, each with a z-component labeled by MJ (or just MS for the spin-only magnetic case). Applying semiclassical Boltzmann statistics, the molar magnetization of such a substance is
N_{A}\bar{m}=\frac{N_{A}\sum\limits_{M_{J}=-J}^{J}{\mu _{M_{J}}e^{{-E_{M_{J}}}/{k_{B}T}\;}}}{\sum\limits_{M_{J}=-J}^{J}{e^{{-E_{M_{J}}}/{k_{B}T}\;}}}=\frac{N_{A}\sum\limits_{M_{J}=-J}^{J}{M_{J}g_{J}\mu _{B}e^{{M_{J}g_{J}\mu _{B}H}/{k_{B}T}\;}}}{\sum\limits_{M_{J}=-J}^{J}{e^{{M_{J}g_{J}\mu _{B}H}/{k_{B}T}\;}}}.
Where \mu _{M_{J}} is the z-component of the magnetic moment for each Zeeman level, so \mu _{M_{J}}=M_{J}g_{J}\mu _{B} – μB is called the Bohr Magneton and gJ is the Landé g-factor which reduces to the free-electron g-factor, gS when J = S. (in this treatment, we assume that the x- and y-components of the magnetization, averaged over all molecules, cancel out because the field applied along the z-axis leave them randomly oreinted.) The energy of each Zeeman level is E_{M_{J}}=-M_{J}g_{J}\mu _{B}H. For temperatures over a few K, {M_{J}g_{J}\mu _{B}H}/{k_{B}T}\;\ll 1, and we can apply the approximation e^{{M_{J}g_{J}\mu _{B}H}/{k_{B}T}\;}\simeq 1+{M_{J}g_{J}\mu _{B}H}/{k_{B}T}\; :
\bar{m}=\frac{\sum\limits_{M_{J}=-J}^{J}{M_{J}g_{J}\mu _{B}e^{{M_{J}g_{J}\mu _{B}H}/{k_{B}T}\;}}}{\sum\limits_{M_{J}=-J}^{J}{e^{{M_{J}g_{J}\mu _{B}H}/{k_{B}T}\;}}}\simeq g_{J}\mu _{B}\frac{\sum\limits_{M_{J}=-J}^{J}{M_{J}\left( 1+{M_{J}g_{J}\mu _{B}H}/{k_{B}T}\; \right)}}{\sum\limits_{M_{J}=-J}^{J}{\left( 1+{M_{J}g_{J}\mu _{B}H}/{k_{B}T}\; \right)}}=\frac{g_{J}^{2}\mu _{B}^{2}H}{k_{B}T}\frac{\sum\limits_{-J}^{J}{M_{J}^{2}}}{\sum\limits_{M_{J}=-J}^{J}{\left( 1 \right)}}.
Which yields,
\bar{m}=\frac{g_{J}^{2}\mu _{B}^{2}H}{3k_{B}T}J(J+1). The molar bulk magnetization is then M=N_{\text{A}}\bar{m}=\frac{N_{\text{A }}}{3k_{B}T}\left[ g_{J}^{2}J(J+1)\mu _{B}^{2}\right]H,
and the molar susceptibility is given by
\chi _{m}=\frac{\partial M}{\partial H}=\frac{N_{\text{A }}}{3k_{B}T}\mu _{\mathrm{eff}}^{2}\text{ ; and }\mu _{\mathrm{eff}}=g_{J}\sqrt{J(J+1)}\mu _{B}.
|}
When orbital angular momentum contributions to the magnetic moment are small, as occurs for most organic radicals or for octahedral transition metal complexes with d3 or high-spin d5 configurations, the effective magnetic moment takes the form (ge = 2.0023... ≈ 2),
\mu _{\mathrm{eff}}\simeq 2\sqrt{S(S+1)}\mu _{B}=\sqrt{n(n+2)}\mu _{B}, where n is the number of unpaired electrons. In other transition metal complexes this yields a useful, if somewhat cruder, estimate.
Materials that are called 'paramagnets', are most often those which exhibit, at least over an appreciable temperature range, magnetic susceptibilities that adhere to the Curie or Curie-Weiss laws. In principle any system that contains atoms, ions or molecules with unpaired spins can be called a paramagnet, but the interactions between them need to be carefully considered.
The narrowest definition would be: a system with unpaired spins that do not interact with each other. In this narrowest sense, the only pure paramagnet is a dilute gas of monatomic hydrogen atoms. Each atom has one non-interacting unpaired electron. Of course, the latter could be said about a gas of lithium atoms but these already possess two paired core electrons that produce a diamagnetic response of opposite sign. Strictly speaking Li is a mixed system therefore, although admittedly the diamagnetic component is weak and often neglected. In the case of heavier elements the diamagnetic contribution becomes more important and in the case of metallic gold it dominates the properties. Of course, the element hydrogen is virtually never called 'paramagnetic' because the monatomic gas is stable only at extremely high temperature; H atoms combine to form molecular H2 and in in so doing, the magnetic moments are lost (quenched), because the spins pair. Hydrogen is therefore diamagnetic and the same holds true for most elements. Although the electronic configuration of the individual atoms (and ions) of most elements contain unpaired spins, it is not correct to call these elements 'paramagnets' because at ambient temperature quenching is very much the rule rather than the exception. However, the quenching tendency is weakest for f-electrons because f (especially 4f) orbitals are radially contracted and they overlap only weakly with orbitals on adjascent atoms. Consequently, the lanthanide elements with incompletely filled 4f-orbitals are paramagnetic or magnetically ordered.[2]
| Material | μeff/μB |
|---|---|
| [Cr(NH3)6]Br3 | 3.77 |
| K3[Cr(CN)6] | 3.87 |
| K3[MoCl6] | 3.79 |
| K4[V(CN)6] | 3.78 |
| [Mn(NH3)6]Cl2 | 5.92 |
| (NH4)2[Mn(SO4)2]•6H20 | 5.92 |
| NH4[Fe(SO4)2]•12H20 | 5.89 |
Thus, condensed phase paramagnets are only possible if the interactions of the spins that lead either to quenching or to ordering are kept at bay by structural isolation of the magnetic centers. There are two classes of materials for which this holds:
As stated above many materials that contain d- or f-elements do retain unquenched spins. Salts of such elements often show paramagnetic behavior but at low enough temperatures the magnetic moments may order. It is not uncommon to call such materials 'paramagnets', when referring to their paramagnetic behavior above their Curie or Néel-points, particularly if such temperatures are very low or have never been properly measured. Even for iron it is not uncommon to say that iron becomes a paramagnet above its relatively high Curie-point. In that case the Curie-point is seen as a phase transition between a ferromagnet and a 'paramagnet'. The word paramagnet now merely refers to the linear response of the system to an applied field, the temperature dependence of which requires an amended version of Curie's law, known as the Curie-Weiss law:
This amended law includes a term θ that describes the exchange interaction that is present albeit overcome by thermal motion. The sign of θ depends on whether ferro- or antiferromagnetic interactions dominate and it is seldom exactly zero, except in the dilute, isolated cases mentioned above.
Obviously, the paramagnetic Curie-Weiss description above TN or TC is a rather different interpretation of the word 'paramagnet' as it does not imply the absence of interactions, but rather that the magnetic structure is random in the absence of an external field at these sufficiently high temperatures. Even if θ is close to zero this does not mean that there are no interactions, just that the aligning ferro- and the anti-aligning antiferromagnetic ones cancel. An additional complication is that the interactions are often different in different directions of the crystalline lattice (anisotropy), leading to complicated magnetic structures once ordered.
Randomness of the structure also applies to the many metals that show a net paramagnetic response over a broad temperature range. They do not follow a Curie type law as function of temperature however, often they are more or less temperature independent. This type of behavior is of an itinerant nature and better called Pauli-paramagnetism, but it is not unusual to see e.g. the metal aluminium called a 'paramagnet', even though interactions are strong enough to give this element very good electrical conductivity.
There are materials that show induced magnetic behavior that follows a Curie type law but with exceptionally large values for the Curie constants. These materials are known as superparamagnets. They are characterized by a strong ferro- or ferrimagnetic type of coupling into domains of a limited size that behave independently from one another. The bulk properties of such a system resembles that of a paramagnet, but on a microscopic level they are ordered. The materials do show an ordering temperature above which the behavior reverts to ordinary paramagnetism (with interaction). Ferrofluids are a good example, but the phenomenon can also occur inside solids, e.g. when dilute paramagnetic centers are introduced in a strong itinerant medium of ferromagnetic coupling such as when Fe is substituted in TlCu2Se2 or the alloy AuFe. Such systems contain ferromagnetically coupled clusters that freeze out at lower temperatures. They are also called mictomagnets.
id:Paramagnetisme ms:Keparamagnetan
ar:مغطسة bg:Парамагнетизъм ca:Paramagnetisme cs:Paramagnetismus de:Paramagnetismus es:Paramagnetismo fa:پارامغناطیس fr:Paramagnétisme ko:상자성 it:Paramagnetismo he:פאראמגנטיות nl:Paramagnetisme ja:常磁性 pl:Paramagnetyzm pt:Paramagnetismo ru:Парамагнетики sk:Paramagnetizmus sl:Paramagnetizem fi:Paramagnetismi sv:Paramagnetism th:พาราแมกเนติก vi:Thuận từ tr:Paramıknatıslık uk:Парамагнетики zh:順磁性
Swami Paramahamsa Hariharananda Giri (Bengali হরিহরানন্দ গিরী, * May 27, 1907 – † December 3, 2002), was an Indian yogi and guru who taught in India as well as in western countries. He was born as Rabindranath Bhattacharya in the hamlet of Habibpur, on the bank of the river Ganga, in the district of Nadia, West Bengal, 65 km from Kolkata.
He was the head of the Kriya Yoga Institute, USA.[1] According to an opinion piece published in the Times of India, Hariharananda was a direct disciple of Sri Yukteswar.[2] However, according to his obituary published in Miami Herald, Hariharananda was taught by a disciple of Paramahamsa Yogananda.[1]
Paramahamsa Hariharananda known as "Baba" (father) to his students, was known as a Kriya Yogi in the lineage of Mahavatar Babaji, Lahiri Mahasaya, Sri Yukteswar, and Paramahamsa Yogananda.[2]
Hariharananda's father Haripada Bhattacharya, an affluent community landlord was a Brahmin. Hariharananda's mother, Nabin Kali, was a woman from the village of Birnagar, Nadia and came from a Brahmin family. Nabin Kali and Haripada had eleven children, five sons and six daughters. Rabindranath (Rabi in short) was the youngest son and later came to be known as Paramahamsa Hariharananda.
According to his own disciple, Swami Sarveshawarananda, at the age of twelve Hariharananda took initiation in the path of Jnana Yoga from a certain Shri Bijoy Krishna Chattopadhyay, after visiting him a couple of times in the company of his brother Pareshnath and brother-in-law, both disciples of his. A disciple of Trailinga Swami of Benares, Bijoy Krishna Chattopadhyaya was known as "Howrah Thakur" because he lived in the Howrah suburb of Kolkata.
In 1932, by his own claims, Hariharananda went to meet the Kriya master, Swami Sri Yukteswar Giri who initiated him into Kriya Yoga, in his Serampore ashram, West Bengal. Hariharananda further claimed that the Swami taught him cosmic astrology, and entreated him to come and live in his Karar Ashram in Puri, Orissa.
However, according to Swami Satyeswarananda Giri — lawyer, monk and a disciple of Swami Satyananda Giri (whom Paramahamsa Hariharananda claimed to have received third Kriya initiation from)—Paramahamsa Hariharananda never met Swami Sri Yukteswar and only fabricated the story of his discipleship to justify his takeover of Karar Ashram.[3] Swami Satyananda Giri, as quoted by his personal student Swami Satyeswarananda Giri, also denounced Paramahamsa Hariharananda's claim of receiving his first Kriya initiation from Swami Sri Yukteswar: Rabindra was initiated into Kriya by Bijoya K. Chatterjee of Howrah, the householder disciple of Sriyukteswar, and learned Kriya from me. However, he received permission to initiate others into Kriya through a letter in October 1951 from Yogananda.[4]
In 1935, he claimed to have met Paramahansa Yogananda, and received the second Kriya initiation from him. In 1938, he renounced the material life and entered his guru's Ashram in Puri, Orissa, starting the life of an ascetic monk as Brahmachari Rabinarayan.
He claimed to receive the third Kriya initiation from Swami Satyananda Giri in 1941, then head of the Karar Ashram and childhood friend of Paramahansa Yogananda.
In 1951 he got written permission from Paramahansa Yogananda to initiate and teach Kriya Yoga.
On May 27, 1959 he took formal monastic vows from the Shankaracharya of Puri Srimad Swami Bharati Krishna Tirtha and was named Swami Hariharananda Giri.
From 1960 to 1974, Hariharananda toured all over India to spread the message of Kriya Yoga. The year 1974 marked his first journey to the West, where he would return every year. His travels took him all over Europe, South America, the United States, and Canada where he established centers and ashrams.
He started charitable dispensaries, educational projects, and cared for the sick, the poor, old widows, orphans and poor children.
Paramahamsa Hariharananda died in Miami, Florida, United States in 2002[1] and was buried in Balighai, Orissa, India that same month [5].
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