DARI PEMBERANTAS BAKTERI SAMPAI MENINGKATKAN DAYA INGAT

Bakal Mati Bosan Berkat Pegagan
Oleh Kompas Cyber Media
Sumber : http://www.depkes.go.id/index.php?option=articles&task=viewarticle&artid=305#
Penulis : Dra. Lucie Widowati, M.Si.Apt; peneliti pada Puslitbang Farmasi dan Obat Tradisional, Jakarta.

Seorang teman bercerita, betapa frustrasinya ia menumpas tuberkulosis (TB) paru-paru. Digempur pakai obat-obatan medis, si penyakit tetap saja eksis. Ia juga panik, karena katanya, bakteri TB bisa kebal terhadap gempuran obat yang diracik apotik. Untunglah, saat nyaris frustrasi, ia “menemukan” pegagan dan kawan-kawan.

Menjalani “takdir” sebagai penderita TB paru-paru memang tak gampang. Jika tidak ulet, alih-alih sembuh, pasien bisa mati bosan. Maklum, proses penyembuhan TB, selain cukup sulit, juga makan waktu lama, berkisar 3 - 6 bulan. Itu pun dengan catatan, pasien berdisiplin minum obat dan rajin memeriksakan diri ke dokter.

Lamanya pengobatan itulah - apalagi jika disertai kendala biaya - yang kerap menyebabkan pasien frustrasi. Ya frustrasi minum obat, ya bosan menanggung derita. Padahal, disiplin minum obat menjadi faktor penentu dalam proses penyembuhan. Pengobatan yang tidak tuntas dapat menyebabkan bakteri TB resisten terhadap beragam obat konvensional, termasuk obat kombinasi.

Dengan kata lain, pasien TB sebenarnya dilarang keras menoleransi kata bosan, apalagi sampai putus asa. Itu sebabnya, buat teman tadi, perjumpaan dengan pegagan dan kawan sejawatnya menjadi sangat berarti. Paling tidak, ia merasa tak “sendiri” lagi menghadapi tuberkulosis. Ketika banyak sanak saudara dan handai taulan menjauh lantaran takut tertular, pegagan dan kawan-kawan menjadi teman paling setia.

Yang paling penting, harga mereka murah dan tak membuat kantung cekak jika dikonsumsi dalam kurun waktu lama.

Mematikan dan bikin bosan

Tuberkulosis pertama kali diketahui keberadaannya tahun 1882 oleh ahli bakteri Jerman, Robert Koch. TB tergolong penyakit menahun nan mematikan.

Menurut Survei Kesehatan Rumah Tangga (KRT, 1995), sebagai penyebab kematian secara umum, TB menduduki peringkat ketiga setelah penyakit kardiovaskuler dan infeksi saluran napas. Namun, khusus di kelas penyakit infeksi, ia ada di posisi nomor satu.

TB umumnya dipicu oleh perumahan yang kurang sehat, terutama di tempat yang memiliki tingkat hunian sangat padat. Bisa juga lantaran makanan yang disantap kurang bergizi, serta kurangnya kesadaran dalam menjaga kebersihan lingkungan. TB ditandai oleh hadirnya bakteri tahan asam bernama mikobakteria tuberkulosis yang memiliki sifat rada beda dari kuman lain pada paru-paru.

Sifat-sifat berbeda itu di antaranya cepat mati bila terkena sinar Matahari, cepat mati jika berada dalam air mendidih, dan akan mati setelah 24 jam terkena cairan karbol 5%. Namun sebaliknya, basil tuberkulosis dapat hidup berminggu-minggu dalam ludah, di tempat yang sejuk, dan berbulan-bulan di tempat yang gelap. Ia juga dapat dengan mudah menular lewat hidung atau mulut.

Penderita TB paru-paru, seperti yang terjadi pada teman tadi, merasa badannya lemah dan nafsu makan berkurang. Timbul batuk yang kadang disertai darah (awalnya cuma sedikit), muka pucat dan berat badan terus berkurang, serta suhu badan naik terutama pada petang dan malam hari. Selain itu, pada malam hari penderita sering mengeluarkan keringat, kadang suaranya berubah menjadi parau atau serak.

Dengan suara parau, teman tadi terus bercerita, termasuk pertemuannya dengan seorang kawan lain yang membawa pencerahan. Kata teman sang teman, mengandalkan obat-obat medis memang tidak salah, tapi melengkapinya dengan meminum air rebusan tumbuhan berkhasiat layak dicoba. “Kalau Tuhan mengizinkan, bisa sembuh lebih cepat,” jelasnya.

Sejak itu, asa teman tadi tumbuh kembali. Ia mencoba mencari tahu, beragam tanaman obat yang telah diteliti oleh berbagai institusi penelitian maupun perguruan tinggi di Indonesia. Ia mendapati, ternyata cukup banyak tanaman obat yang secara empiris telah dikenal masyarakat. Beberapa tumbuhan yang sempat tercatat, antara lain pegagan, singawalang, bunga tembelekan, dan bumbu tali.

Menghambat & menghancurkan

Pegagan atau nama kerennya Centella asiatica itu tumbuhan liar yang ada di dataran rendah, sampai sekitar 2.500 m di atas permukaan air laut.

Secara empiris, biasa digunakan sebagai tonik, antiinfeksi, antirematik, penenang, mempercepat penyembuhan luka, dan diuretik. Berbagai penelitian telah dilakukan guna mendukung manfaat empirisnya.

Misalnya, penelitian yang merujuk pegagan sebagai antiinflamasi, antioksidan, antitumor, atau untuk meningkatkan daya ingat (susunan saraf pusat), eksem (luka terbuka), dan hepatitis. Hal itu berkaitan dengan kandungan senyawa yang dimiliki pegagan, yaitu asiaticiside, thankuniside, medecassoside, brahmoside, brahminoside, madastic acid, vitamin B1, B2, dan B6.

Penduduk asli India dan Malaysia konon suka menanam dan menyimpan pegagan dalam bentuk ready stock, agar siap digunakan sewaktu-waktu. Oleh warga dua bangsa itu pegagan lazim disimpan dalam bentuk kering untuk mengobati beragam penyakit. Terkadang mereka juga membuat jus daun segar, yang diminum untuk menghilangkan pusing ringan.

Dari berbagai penelitian in vitro terhadap pegagan menemukan kemampuannya menghancurkan berbagai bakteri penyebab infeksi, seperti Staphylococcus aureus, Escherechia coli, Pseudomonas aeruginosa, Salmonella typhi, dan sejenisnya. Sementara dalam bentuk infus atau ekstrak etanol, tumbuhan ini dipercaya dapat menghambat pertumbuhan bakteri.

Laorpuksa A. dan kawan-kawan dalam penelitian pada 1988 membuktikan, estrak air pegagan dapat melawan bakteri yang menyebabkan infeksi pada saluran napas. Sementara Herbert D. dan kawan-kawan dari Tuberculosis Research Center di India mencoba efek pegagan pada bakteri tuberkulosis H37Rv secara in vitro. Hasilnya, pegagan tidak langsung berefek pada bakteri tuberkulosis. Namun, Herbert menyarankan penelitian lebih lanjut terhadap senyawa aktif asiaticoside.

Feeling Herbert terbukti benar. Berdasarkan penelitian lanjutan, senyawa aktif pegagan itu ternyata dapat melawan Mycobakterium tuberculosis dan Bacillus leprae (Oliver-Bever, 1986). Penelitian berikutnya yang dilakukan Walter H. Lewis juga menyatakan, pegagan termasuk kelompok tanaman yang menghasilkan zat seperti antibiotika dan asiaticoside.

Keampuhan pegagan juga telah diuji coba oleh Boeteau P. dan kawan-kawan, yang menginokulasi binatang percobaan marmut dengan bakteri basilus tuberkulosis selama 15 hari. Injeksi 0,5 ml 4% asiaticoside yang diberikan pada marmut, terbukti dapat mengurangi jumlah lesi tuberkular di paru-paru, hati, dan limpa. Senyawa asiaticoside membuat pegagan tak hanya dapat menghambat pertumbuhan bakteri tuberkulosis, tapi juga berpotensi sebagai imunomodulator - peningkat daya tahan tubuh.

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Leonardo da Vinci (1452-1519)

Florentine artist, one of the great masters of the High Renaissance, celebrated as a painter, sculptor, architect, engineer, and scientist. His profound love of knowledge and research was the keynote of both his artistic and scientific endeavors. His innovations in the field of painting influenced the course of Italian art for more than a century after his death, and his scientific studies—particularly in the fields of anatomy, optics, and hydraulics—anticipated many of the developments of modern science.


EARLY LIFE IN FLORENCE
Leonardo was born in the small town of Vinci, in Tuscany (Toscana), near Florence. He was the son of a wealthy Florentine notary and a peasant woman. In the mid-1460s the family settled in Florence, where Leonardo was given the best education that Florence, a major intellectual and artistic center of Italy, could offer. He rapidly advanced socially and intellectually. He was handsome, persuasive in conversation, and a fine musician and improviser.

About 1466 he was apprenticed as a garzone (studio boy) to Andrea del Verrocchio, the leading Florentine painter and sculptor of his day. In Verrocchio's workshop Leonardo was introduced to many activities, from the painting of altarpieces and panel pictures to the creation of large sculptural projects in marble and bronze. In 1472 he was entered in the painter's guild of Florence, and in 1476 he was still considered Verrocchio's assistant. In Verrocchio's Baptism of Christ (1470?, Uffizi, Florence), the kneeling angel at the left of the painting is by Leonardo.

In 1478 Leonardo became an independent master. His first commission, to paint an altarpiece for the chapel of the Palazzo Vecchio, the Florentine town hall, was never executed. His first large painting, The Adoration of the Magi (begun 1481, Uffizi), left unfinished, was ordered in 1481 for the Monastery of San Donato a Scopeto, Florence. Other works ascribed to his youth are the so-called Benois Madonna (1478?, Hermitage, Saint Petersburg), the portrait Ginevra de' Benci (1474?, National Gallery, Washington, D.C.), and the unfinished Saint Jerome (1481?, Pinacoteca, Vatican).

YEARS IN MILAN

About 1482 Leonardo entered the service of the duke of Milan, Ludovico Sforza, having written the duke an astonishing letter in which he stated that he could build portable bridges; that he knew the techniques of constructing bombardments and of making cannons; that he could build ships as well as armored vehicles, catapults, and other war machines; and that he could execute sculpture in marble, bronze, and clay. He served as principal engineer in the duke's numerous military enterprises and was active also as an architect. In addition, he assisted the Italian mathematician Luca Pacioli in the celebrated work Divina Proportione (1509).



Evidence indicates that Leonardo had apprentices and pupils in Milan, for whom he probably wrote the various texts later compiled as Treatise on Painting (1651; translated 1956). The most important of his own paintings during the early Milan period was The Virgin of the Rocks, two versions of which exist (1483-1485, Louvre, Paris; 1490s to 1506-1508, National Gallery, London); he worked on the compositions for a long time, as was his custom, seemingly unwilling to finish what he had begun. From 1495 to 1497 Leonardo labored on his masterpiece, The Last Supper, a mural in the refectory of the Monastery of Santa Maria delle Grazie, Milan.

Unfortunately, his experimental use of oil on dry plaster (on what was the thin outer wall of a space designed for serving food) was technically unsound, and by 1500 its deterioration had begun. Since 1726 attempts have been made, unsuccessfully, to restore it; a concerted restoration and conservation program, making use of the latest technology, was begun in 1977 and is reversing some of the damage. Although much of the original surface is gone, the majesty of the composition and the penetrating characterization of the figures give a fleeting vision of its vanished splendor.

During his long stay in Milan, Leonardo also produced other paintings and drawings (most of which have been lost), theater designs, architectural drawings, and models for the dome of Milan Cathedral. His largest commission was for a colossal bronze monument to Francesco Sforza, father of Ludovico, in the courtyard of Castello Sforzesco. In December 1499, however, the Sforza family was driven from Milan by French forces; Leonardo left the statue unfinished (it was destroyed by French archers, who used the terra cotta model as a target) and he returned to Florence in 1500.


RETURN TO FLORENCE
In 1502 Leonardo entered the service of Cesare Borgia, duke of Romagna and son and chief general of Pope Alexander VI. In his capacity as the duke's chief architect and engineer, Leonardo supervised work on the fortresses of the papal territories in central Italy. In 1503 he was a member of a commission of artists who were to decide on the proper location for the David (1501-1504, Accademia, Florence), the famous colossal marble statue by the Italian sculptor Michelangelo, and he also served as an engineer in the war against Pisa. Toward the end of the year Leonardo began to design a decoration for the great hall of the Palazzo Vecchio. The subject was the Battle of Anghiari, a Florentine victory in its war with Pisa. He made many drawings for the decoration and completed a full-size cartoon, or sketch, in 1505, but he never finished the wall painting. The cartoon itself was destroyed in the 17th century, and the composition survives only in copies, of which the most famous is the one by the Flemish painter Peter Paul Rubens (1615?, Louvre).

During this second Florentine period, Leonardo painted several portraits, but the only one that survives is the famous Mona Lisa (1503-1506, Louvre). One of the most celebrated portraits ever painted, it is also known as La Gioconda, after the presumed name of the woman's husband. Leonardo seems to have had a special affection for the picture, for he took it with him on all of his subsequent travels.

LATER TRAVELS AND DEATH
In 1506 Leonardo again went to Milan, at the summons of its French governor, Charles d'Amboise. The following year he was named court painter to King Louis XII of France, who was then residing in Milan. For the next six years Leonardo divided his time between Milan and Florence, where he often visited his half brothers and half sisters and looked after his inheritance. In Milan he continued his engineering projects and worked on an equestrian figure for a monument to Gian Giacomo Trivulzio, commander of the French forces in the city; although the project was not completed, drawings and studies have been preserved. From 1514 to 1516 Leonardo lived in Rome under the patronage of Pope Leo X. He was housed in the Palazzo Belvedere in the Vatican and seems to have been occupied principally with scientific experimentation. In 1516 he traveled to France to enter the service of King Francis I. He spent his last years at the Château de Cloux, near Amboise, where he died.

PAINTINGS
Although Leonardo produced a relatively small number of paintings, many of which remained unfinished, he was nevertheless an extraordinarily innovative and influential artist. During his early years, his style closely paralleled that of Verrocchio, but he gradually moved away from his teacher's stiff, tight, and somewhat rigid treatment of figures to develop a more evocative and atmospheric handling of composition. The early painting The Adoration of the Magi introduced a new approach to composition, in which the main figures are grouped in the foreground, while the background consists of distant views of imaginary ruins and battle scenes.



Leonardo's stylistic innovations are even more apparent in The Last Supper, in which he represented a traditional theme in an entirely new way. Instead of showing the 12 apostles as individual figures, he grouped them in dynamic compositional units of three, framing the figure of Christ, who is isolated in the center of the picture. Seated before a pale distant landscape seen through a rectangular opening in the wall, Christ—who is about to announce that one of those present will betray him—represents a calm nucleus while the others respond with animated gestures. In the monumentality of the scene and the weightiness of the figures, Leonardo reintroduced a style pioneered more than a generation earlier by Masaccio, the father of Florentine painting.

The Mona Lisa, Leonardo's most famous work, is as well known for its mastery of technical innovations as for the mysteriousness of its legendary smiling subject. This work is a consummate example of two techniques—sfumato and chiaroscuro—of which Leonardo was one of the first great masters. Sfumato is characterized by subtle, almost infinitesimal transitions between color areas, creating a delicately atmospheric haze or smoky effect; it is especially evident in the delicate gauzy robes worn by the sitter and in her enigmatic smile. Chiaroscuro is the technique of modeling and defining forms through contrasts of light and shadow; the sensitive hands of the sitter are portrayed with a luminous modulation of light and shade, while color contrast is used only sparingly.

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Cosa Aranda, Pebisnis Dunia Maya Asal Surabaya, Berkantor di Kamar, Raup 90 juta sebulan

Kalau ada orang menjadi kaya setelah bersusah-payah membangun bisnis bertahun-tahun, itu hal biasa. Tetapi jika mendengar anak muda berkantong tebal dengan cara mudah, jelas menarik untuk ditelusuri.

Cosa Aranda jutawan. Nyaris tak ada yang tahu. Hanya mereka yang rajin keluar masuk situs milik Cosa, panggilannya, yang paham betul. bahkan teman kuliahnya baru bulan lau tahu bahwa orang inilah yang sering dibicarakan di Google AdSense dan Adwords.

Memiliki Penghasilan dari iklan yang masuk di situs milik Google ini awalnya memang mimpi bercampur coba-coba. "Jika ada yang mengatakan berbisnis iklan di Internet mudah menghasilkan uang, itu bohong", Kata lelaki 25 tahun ini saat ditemui di rumahnya di Surabaya, Rabu (1/8) Berbeda dengan banyak orang yang menganggap bisnis seperti ini bisa dilakukan sambil lalu dengan hasil tak terbatas, COsa justru menganggap pekerjaan ini berat. Sangat berat.

Ketika pertama kali membuat situs yang berawal dari blog pribadi, dia harus jungkir balik menghabiskan waktu 8-10 jam sehari. Selama itu dia tidak keluar kamar. Dan ini terjadi pada bulan-bulan pertama saat membangun www.cosaaranda.com April 2005.

Percobaan demi percobaan dilakukan dengan telaten. Kesulitan utama yang dialami mahasiswa semester akhir jurusan Sistem Informasi Sekolah Tinggi Manajemen Informatikan dan Teknik Komputer (Stikom) surabaya ini adalah melakukan promosi. Karena niat awalnya belajar dan mencoba, Cosa memilih cara gratis lewat search engine. setelah itu, menunggu "dan berdo'a", kelakarnya.

Penantian itu tak sia-sia. Tiga minggu setelah diluncurkan, ada juga iklan yang datang. semakin banyak pengunjung yang datang ke situsnya, makin besar kemungkinan iklan di klik. Jika pengguna melakukan transaksi, maka publisher, pemilik situs yang sudah bergabung dengan Google Adsense dan surah pula memasang iklan AdSense di situs mereka, mendapat fee. biasanya 20 persen dari harga iklan.

"Bulan pertama saya mendapat 1 dollar AS. wah.. senang sekali. Ternyata laku juga", kata sulung dari dua bersaudara yang terkesan berhati-hati ketika berbincang.

Satu dolar AS inilah yang memacu Cosa memoles situsnya. Tidak dengan tampilan artistik tetapi dengan isi yang paling dibutuhkan orang. Dia meng up date data setiap hari. Dengan demikian setiap hari pula orang berkunjung karena membutuhkan informasi terkini dan penting.

Sekarang situs ini dikunjungi 800-1.000 pengguna setia hari. Ini membuat perolehan Cosa dimungkinkan makin besar. Ledakan penghasilannya baru di dapat tiga bulan setelah menunggu dan berdoa. Jika Oktober 2005 penghasilannya Rp. 1 dolar AS, akhir juli 2007 dia mendapat kiriman cek 5.000 dolar AS atau lebih dari Rp. 45 juta. Ini baru perolehan lewat Google Adsense. Padahal dia juga memiliki jalur lain, Adwords. Jika semua ditotal, Juli Kemarin Cosa mendapat lebih Rp. 90 juta.

Cosa memang kaya, tetapi belajar dari buku Seven Years To Seven Figures karangan Michael Masterson, kaya menurut Cosa adalah kondisi saat segala kebutuhan terpenuhi, baik yang bersifat sekunder maupun darurat atau mendadak. "Saya tabung uangnya. Saya ingin punya rumah sendiri", kata lelaki yang mengaku belum punya kekasih ini.

Putra pasangan Drs. Toto, Soedjianto dan Ir. Yustisia Martani ini ingin menjadi full time blogger. Awalnya keluarga dari Jawa Tengah ini tak sadar jika Cosa punya bisnis di kamarnya. Yang mereka tahu anak mereka 'gila' internet. Baru setelah ada kiriman cek, mereka paham.

Tetapi sambil bergurau Cosa mengaku tak tahu harus mengatakan apa pada calon mertua bila ditanya pekerjaan. "Pokoknya saya jawab kerja di Internet. Mudah-mudahan bisa mengerti", katanya sambil tertawa ngakak. Karena semuanya sudah tertata, sekarang Cosa hanya butuh dua jam untuk up date dan setelah itu waktu luangnya diisi dengan jalan-jalan ke mal dan membaca. Jangan salah, bukan buku komputer atau teknologi yang jadi favoritnya melainkan komik. Tahun ini atas desakan para kerabat di situsnya, akhirnya Cosa membuat workshop di warnet. Tiga kali workshop dilakukan di Surabaya. Pesertanya tak lebih dari 30 orang.

"Saya lebih suka kelas kecil karena semua pertanyaan bisa dijawab dan langsung praktik", tutur pelahap film apa saja ini yang tidak memungut biaya kecuali untuk membayar pemakaian internet di warnet.

"Di Jogjakarta banyak publisher yang penghasilannya lebih hebat. Saya belum apa-apa. Tetapi kalau ada yang mau mengikuti cara ini, ayo sama-sama belajar", tuturnya.

Sumber:

Harian Surya 2 Agustus 2007

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Discovery and use

Main article: Timeline of hydrogen technologies

Hydrogen gas, H₂, was first artificially produced and formally described by T. Von Hohenheim (also known as Paracelsus, 1493–1541) via the mixing of metals with strong acids.^[58] He was unaware that the flammable gas produced by this chemical reaction was a new chemical element. In 1671, Robert Boyle rediscovered and described the reaction between iron filings and dilute acids, which results in the production of hydrogen gas.^[59] In 1766, Henry Cavendish was the first to recognize hydrogen gas as a discrete substance, by identifying the gas from a metal-acid reaction as "inflammable air" and further finding in 1781 that the gas produces water when burned. He is usually given credit for its discovery as an element.^[60][61] In 1783, Antoine Lavoisier gave the element the name of hydrogen (from the Greek hydro meaning water and genes meaning creator)^[62] when he and Laplace reproduced Cavendish's finding that water is produced when hydrogen is burned.^[61]

Hydrogen was liquefied for the first time by James Dewar in 1898 by using regenerative cooling and his invention, the vacuum flask.^[61] He produced solid hydrogen the next year.^[61] Deuterium was discovered in December 1931 by Harold Urey, and tritium was prepared in 1934 by Ernest Rutherford, Mark Oliphant, and Paul Harteck.^[60] Heavy water, which consists of deuterium in the place of regular hydrogen, was discovered by Urey's group in 1932.^[61] François Isaac de Rivaz built the first internal combustion engine powered by a mixture of hydrogen and oxygen in 1806. Edward Daniel Clarke invented the hydrogen gas blowpipe in 1819. The Döbereiner's lamp and limelight were invented in 1823.^[61]

The first hydrogen-filled balloon was invented by Jacques Charles in 1783.^[61] Hydrogen provided the lift for the first reliable form of air-travel following the 1852 invention of the first hydrogen-lifted airship by Henri Giffard.^[61] German count Ferdinand von Zeppelin promoted the idea of rigid airships lifted by hydrogen that later were called Zeppelins; the first of which had its maiden flight in 1900.^[61] Regularly-scheduled flights started in 1910 and by the outbreak of World War I in August 1914 they had carried 35,000 passengers without a serious incident. Hydrogen-lifted airships were used as observation platforms and bombers during the war.

The first non-stop transatlantic crossing was made by the British airship R34 in 1919. Regular passenger service resumed in the 1920s and the discovery of helium reserves in the United States promised increased safety, but the U.S. government refused to sell the gas for this purpose. Therefore, H₂ was used in the Hindenburg airship, which was destroyed in a midair fire over New Jersey on May 6, 1937.^[61] The incident was broadcast live on radio and filmed. Ignition of leaking hydrogen as widely assumed to be the cause but later investigations pointed to ignition of the aluminized fabric coating by static electricity. But the damage to hydrogen's reputation as a lifting gas was already done.

Role in quantum theory

Hydrogen emission spectrum lines in the visible range

Because of its relatively simple atomic structure, consisting only of a proton and an electron, the hydrogen atom, together with the spectrum of light produced from it or absorbed by it, has been central to the development of the theory of atomic structure.^[63] Furthermore, the corresponding simplicity of the hydrogen molecule and the corresponding cation H₂⁺ allowed fuller understanding of the nature of the chemical bond, which followed shortly after the quantum mechanical treatment of the hydrogen atom had been developed in the mid-1920s.

One of the first quantum effects to be explicitly noticed (but not understood at the time) was a Maxwell observation involving hydrogen, half a century before full quantum mechanical theory arrived. Maxwell observed that the specific heat capacity of H₂ unaccountably departs from that of a diatomic gas below room temperature and begins to increasingly resemble that of a monatomic gas at cryogenic temperatures. According to quantum theory, this behavior arises from the spacing of the (quantized) rotational energy levels, which are particularly wide-spaced in H₂ because of its low mass. These widely spaced levels inhibit equal partition of heat energy into rotational motion in hydrogen at low temperatures. Diatomic gases composed of heavier atoms do not have such widely spaced levels and do not exhibit the same effect.^[64]

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