Sejarah AK-47 (History of AK-47)

Mikhail Kalashnikov (Pembuat AK-47) lahir 10 November 1919 di desa Kurya, Uni Soviet dari keluarga petani miskin. Di usia 19 tahun, Kalashnikov ikut wajib militer dan bergabung dengan Resimen Tank ke-24, Divisi Tank ke-12 dimana ia menamatkan sekolah mekanik tank dan menjadi montir-pengemudi tank dan mencapai pangkat sersan senior (komandan tank). Pada Oktober 1941, dalam peperangan sengit di Bryansk, Kalashnikov terluka parah dan harus dirawat di rumah sakit.

Ketika di rumah sakit inilah ia memiliki ide untuk merancang sebuah senapan submesin.  Kemampuan Kalashnikov sebagai perancang mengundang perhatian. Ia sempat bekerja di Moscow Aviation Institute. Mulai tahun 1942, Kalashnikov bekerja di Central Research Small Arms Range of the Main Ordnance Directorate of the Red Army.

Idiopathic Cardiomyopathy

Cardiomyopathy is a term used to refer to a group of heart disease disorders that are related to the heart muscle. There are 4 specific types of cardiomyopathy including restrictive, dilated, hypertrophic and alcoholic cardiomyopathy. Each type can have various causes such as alcohol and drug abuse, eating disorders, hereditary or genetic disorders or even pregnancy. In cases where the cardiomyopathy cause is not clearly known, the patient may be diagnosed with idiopathic cardiomyopathy. Idiopathic refers unknown etiology or unknown cause. 

BUDIDAYA RUMPUT LAUT

Lahan rumput laut

Lahan sebagai habitat untuk masing-masing jenis rumput laut mempunyai sifat yang berbeda-beda.  Untuk pertumnuhan Eucheuma beberapa beberapa persyaratan lingkungan diperlukan, yakni :

• Subsatrat stabil, dasar perairan terdiri atas campuran karang mati dan karang kasar, terlindung dari ombak yang terlalu kuat, dan umumnya di daerah terumbu karang.
• Tempat dan lingkungan perairan tidak mengalami pencemaran.
• Kedalaman air pada waktu surut terendah 10 sampai 30 cm.
• Perairan dilalui arus tetap dari laut lepas sepanjang tahun.
• Kecepatan arus antara 20-40 m per menit.
• Jauh dari mulut sungai.
• Perairan tidak mengandung lumpur dan airnya jernih.
• Suhu air laut sekitar 27-30⁰C, dan kadar garam air sekitar 30-37⁰/₀₀.

CHLOROPHENOL (Identity, Physical and Chemical Properties, Analytical Methods)

Chlorophenols (CPs) are organic chemicals formed from phenol (1-hydroxybenzene) by substitution in the phenol ring with one or more atoms of chlorine.  Nineteen congeners are posible, ranging from monochlorophenols to the fully chlorinated pentachlorophenol (PCB).  Chlorophenols, particularly trichlorophenols (T₃CP), tetrachlorophenols (T₄CP), and PCP, are also available as sodium or potassium salts.

Chlorophenols are solids at room temperature, except for 2-MCP, which is a liquid.  The aqueous solubility of chlorophenols are up to four orders of magnitude more soluble in water than the parent compounds.  The acidity of chlorophenols increases as the number of chlorine substitutions increases.  The n-octanol/water partition coefficients of chlorophenols increases with chlorination, indicating a propensity for the higher chlorophenols to bioaccumulate.  Taste and odour thresholds are quite low.

BIOCHEMISTRY OF TERATOGENESIS

Teratology is the science of birth defects caused by radiation, viruses, and chemicals, including drug.  Xenobiotic chemical species that cause birth defects are called teratogens.  Teratogens affect developing embryos adversely, often with remarkable specificity in regard to effect and stage of embryo development when exposed.  A teratogen may cause a specific effect when exposure occurs on a definite number of days after conception; if exposure occurs only a few days sooner or later, no effect, or an entirely different one, may be observed.  Although mutations in germ cells (egg or sperm cells) may cause birth deffects (e.g. Down’s syndrome), teratology usually deals with defects arising from damage to embryonic or fetal cells.

ALGAE MERAH (RED ALGAE)

 Rumput laut (algae laut bentik) yang bernilai ekonomis penting di Indonesia diantaranya adalah jenis Rhodophyta (algae merah).  Algae merah ditandai oleh sifat-sifat sebagai berikut :

• Dalam reproduksinya tidak mempunyai stadia gamet berbulu cambuk.
• Reproduksi seksual dengan karpogonia dan spermatia.
• Pertumbuhan bersifat uniaksial (satu sel di ujung thallus) dan multiaksial (banyak sel di ujung thallus).
• Alat pelekat (holdfast) terdiri dari perakaran sel tunggal atau sel banyak.
• Mempunyai pigmen fikobilin yang terdiri dari fikoeretrin (berwarna merah) dan fikosianin (berwarna biru).
• Bersifat adaptasi kromatik, yaitu mempunyai penyesuaian antara proporsi pigmen dengan berbagai kualitas pencahayaan dan dapat menimbulkan berbagai warna “thalli” seperti : pirang, violet, merah tua, merah muda, coklat, kuning, dan hijau.
• Mempunyai persediaan makanan berupa kanji (floridean starch).
• Dalam dinding selnya terdapat selulosa, agar, karagenan, porpiran, dan furselaran.

BIOCHEMISTRY OF CARCINOGENESIS

Cancer is a condition characterized by the uncontrolled replication and growth of the body’s own cells (somatic cells).  It is now generally believed that many – and perhaps most – cancers are started by the action of synthetic and naturrally occuring chemicals (in some cases viruses cause cancer).  The role xenobiotic chemicals in causing cancer is called chemical carcinogenesis.  It is often regarded as the single most important facet of toxicology and clearly the one that receives the most publicity.

Despite large expenditures of time and money on the subject, the biochemical bases of chemical carcinogenesis are not well understood.  The overall processes for the induction of cancer may be quite complex, involving numerous steps.  It is generally recognized that there are two major steps : an initiation stage followed by a promotional stage.  Chemical carcinogens are often mutagens and it is believed that in many cases cancerous cells result from mutations of normal cells exposed to carcinogens.  This implies that that chemical carcinogens alter DNA in a manner such that an “outlaw cell” is formed that continues to replicate itself and form cancerous tissue.

BIOCHEMISTRY OF MUTAGENESIS

Mutagenesis is the phenomenon in which inheritable traits result from alterations of DNA.  Although mutation is a normally occurring process that gives rise to diversity in species, most mutations are harmful.  The toxicants that cause mutations are known as mutagens.  These toxicants, often the same as those that cause cancer or birth defects, are a major toxicological concern.

To understand the biochemistry of mutagenesis, it is important to know that DNA contains the nitrogenous bases adenine, guanine, cytosine, and thymine.  The order in which these bases occur in DNA determines the nature and structure of newly-produced RNA, a substance produced as a step in the synthesis of new proteins and enzymes in cells.  Exchange, addition, or deletion of any of the nitrogenous bases in DNA alters the nature of RNA produced and can change vital life processes, such as the synthesis of an important enzyme.  This phenomenon, which can be caused by xenobiotic compounds, is a mutation that can be passed on to progeny, ussually with detrimental results.

TEMBAGA (CUPPER)

Tembaga memiliki nama kimia cupprum dan dilambangkan dengan Cu.  Unsur logam ini berbentuk kristal dengan warna kemerahan.  Dalam sistem periodik unsur kimia, tembaga menempati posisi dengan nomor atom (NA) 29 dan mempunyai berat atom (BA) 63,546.

Tembaga dapat ditemukan dalam bentuk logam bebas di alam akan tetapi lebih banyak ditemukan dalam bentuk senyawa padat (mineral).  Di perairan tembaga dapat ditemukan dalam bentuk senyawa ion seperti CuCO₃^- dan CuOH^-.  Pada batuan mineral tembaga dapat ditemukan dalam bentuk :

• chalcocote (Cu₂S)
• covellite (CuS)
• chalcopyrite (CuFeS₂)
• bornite (Cu₅FeS₄)
• enargite (Cu₃(AsSb)S₄)

TIMBAL (LEAD / PLUMBUM)

Timbal (Lead) dalam keseharian dikenal sebagai timah hitam atau dalam bahasa ilmiahnya adalah plumbum (Pb).  Dalam sistem periodik unsur kimia timbal termasuk logam golongan IV A dengan nomor atom (NA) 82 dan bobot atom (BA) 207,2.  Di alam terdapat 4 macam isotop timbal, yaitu :

1. Timbal 204 (Pb²⁰⁴) diperkirakan berjumlah 1,48% dari seluruh isotop timbal.
2. Timbal 206 (Pb²⁰⁶) diperkirakan berjumlah 23,60% dari seluruh isotop timbal.
3. Timbal 207 (Pb²⁰⁷) diperkirakan berjumlah 22,60% dari seluruh isotop timbal.
4. Timbal 208 (Pb²⁰⁸) diperkirakan berjumlah 52,32% dari seluruh isotop timbal.

MERKURI (AIR RAKSA / HYDRARGYRUM)

Merkuri atau air raksa (Hydrargyrum)merupakan logam yang berbentuk cair pada suhu ruangan dan dilambangkan dengan Hg.  Dalam system periodik unsur menempati urutan ke 80 (nomor atom 80) dengan bobot atom (BA) sebesar 200,59.  Merkuri dihasilkan dari biji sinabar (HgS) dengan kandungan merkuri antara 0,1 – 4%. Reaksinya adalah :

HgS + O₂ ==> Hg + S