Gold is a chemical element with the symbol Au and atomic number 79, making it one of the higher atomic number elements that occur naturally. In its purest form, it is a bright reddish yellow, soft and ductile metal. Chemically, gold is a group 11 element, it is solid under standard conditions. Gold occurs in free elemental form, as nuggets or grains, in rocks, in veins, in alluvial deposits, it occurs in a solid solution series with the native element silver and naturally alloyed with copper and palladium. Less it occurs in minerals as gold compounds with tellurium. Gold is resistant to most acids, though it does dissolve in aqua regia, a mixture of nitric acid and hydrochloric acid, which forms a soluble tetrachloroaurate anion. Gold is insoluble in nitric acid, which dissolves silver and base metals, a property that has long been used to refine gold and to confirm the presence of gold in metallic objects, giving rise to the term acid test. Gold dissolves in alkaline solutions of cyanide, which are used in mining and electroplating.

Gold dissolves in mercury, forming amalgam alloys. A rare element, gold is a precious metal, used for coinage and other arts throughout recorded history. In the past, a gold standard was implemented as a monetary policy, but gold coins ceased to be minted as a circulating currency in the 1930s, the world gold standard was abandoned for a fiat currency system after 1971. A total of 186,700 tonnes of gold exists above ground, as of 2015; the world consumption of new gold produced is about 50% in jewelry, 40% in investments, 10% in industry. Gold's high malleability, resistance to corrosion and most other chemical reactions, conductivity of electricity have led to its continued use in corrosion resistant electrical connectors in all types of computerized devices. Gold is used in infrared shielding, colored-glass production, gold leafing, tooth restoration. Certain gold salts are still used as anti-inflammatories in medicine; as of 2017, the world's largest gold producer by far was China with 440 tonnes per year.

Gold is the most malleable of all metals. It can be drawn into a monoatomic wire, stretched about twice before it breaks; such nanowires distort via formation and migration of dislocations and crystal twins without noticeable hardening. A single gram of gold can be beaten into a sheet of 1 square meter, an avoirdupois ounce into 300 square feet. Gold leaf can be beaten thin enough to become semi-transparent; the transmitted light appears greenish blue, because gold reflects yellow and red. Such semi-transparent sheets strongly reflect infrared light, making them useful as infrared shields in visors of heat-resistant suits, in sun-visors for spacesuits. Gold is a good conductor of electricity. Gold has a density of 19.3 g/cm3 identical to that of tungsten at 19.25 g/cm3. By comparison, the density of lead is 11.34 g/cm3, that of the densest element, osmium, is 22.588±0.015 g/cm3. Whereas most metals are gray or silvery white, gold is reddish-yellow; this color is determined by the frequency of plasma oscillations among the metal's valence electrons, in the ultraviolet range for most metals but in the visible range for gold due to relativistic effects affecting the orbitals around gold atoms.

Similar effects impart a golden hue to metallic caesium. Common colored gold alloys include the distinctive eighteen-karat rose gold created by the addition of copper. Alloys containing palladium or nickel are important in commercial jewelry as these produce white gold alloys. Fourteen-karat gold-copper alloy is nearly identical in color to certain bronze alloys, both may be used to produce police and other badges. Fourteen- and eighteen-karat gold alloys with silver alone appear greenish-yellow and are referred to as green gold. Blue gold can be made by alloying with iron, purple gold can be made by alloying with aluminium. Less addition of manganese and other elements can produce more unusual colors of gold for various applications. Colloidal gold, used by electron-microscopists, is red. Gold has only one stable isotope, 197Au, its only occurring isotope, so gold is both a mononuclidic and monoisotopic element. Thirty-six radioisotopes have been synthesized, ranging in atomic mass from 169 to 205.

The most stable of these is 195Au with a half-life of 186.1 days. The least stable is 171Au. Most of gold's radioisotopes with atomic masses below 197 decay by some combination of proton emission, α decay, β+ decay; the exceptions are 195Au, which decays by electron capture, 196Au, which decays most by electron capture with a minor β− decay path. All of gold's radioisotopes with atomic masses above 197 decay by β− decay. At least 32 nuclear isomers have been characterized, ranging in atomic mass from 170 to 200. Within that range, only 178Au, 180Au, 181Au, 182Au, 188Au do not have isomers. Gold's most stable isomer is 198m2Au with a half-life of 2.27 days. Gold's least stable isomer is 177m2Au with a half-life of only 7 ns. 184m1Au has three decay paths: β+ decay, isomeric transition, alpha decay. No other isomer or isotope of g

Adenosarcoma is a rare malignant tumor that occurs in women of all age groups, but most post-menopause. Adenosarcoma arises from mesenchymal tissue and has a mixture of the tumoral components of an adenoma, a tumor of epithelial origin, a sarcoma, a tumor originating from connective tissue; the adenoma, or epithelial component of the tumor, is benign, while the sarcomatous stroma is malignant. The most common site of adenosarcoma formation is the uterus, but it can occur in the cervix and ovaries, it more arises in the vagina and fallopian tubes as well as primary pelvic or peritoneal sites, such as the omentum in those with a history of endometriosis. The rare cases of adenosarcoma outside the female genital tract occur in the liver, kidney, as well as the intestine and are associated with endometriosis. Mullerian adenosarcoma with sarcomatous overgrowth is a aggressive form of adenosarcoma, characterized by post-operative recurrence and metastases when diagnosed at an early stage. Sarcomatous overgrowth is diagnosed when the sarcomatous portion of the adenosarcoma makes up more than 25% of the tumor.

Adenosarcomas do not have distant metastases, but they have a propensity for local recurrence. Uterine adenosarcoma are a subtype of uterine sarcomas. Uterine sarcomas account for 3 to 9 % of uterine cancers, 5.5 to 9 % of uterine sarcomas are adenosarcomas. The most common presenting symptom is abnormal vaginal bleeding. Other symptoms include abdominal mass, or vaginal discharge. Uterine adenosarcoma arise from the endometrium. Uterine adenosarcomas have the highest incidence in perimenopasual and postmenopausal women with a mean age of 50 years, but some incidence among children. Survival is better compared to other types of uterine sarcomas; the prognosis of uterine adenosarcoma depends on the stage. No definitive causes of adenosarcoma have been identified. Potential risk factors include a medical history of endometriosis and use of estrogen modulating agents such as tamoxifen. Other potential risk factors include previous pelvic irradiation and prolonged estrogen exposure The standard care of treatment is total abdominal hysterectomy with bilateral salpingo-oophorectomy.

Lymphadenectomy is not performed as the incidence of lymph node metastasis is rare. There is hormone therapy, or radiation therapy; because of the rarity of adenosarcoma, there is limited data to guide treatment decisions in regard to recurrent or metastatic tumors. Chemotherapy may be considered in patients with recurrence or tumors unable to be removed through surgery, it has been suggested that uterine adenosarcomas can respond to doxorubicin/ifosfamide and gemcitabine/docetaxel chemotherapy. The use of hormone therapy in recurrent or metastatic disease is limited to case reports. Survival is influenced by the presence of myometrial invasion, sarcomatous overgrowth, lymphovascular invasion and the presence of heterologous elements, which are features in the tumor not native to the tissue of origin such as rhabdomyoblastic differentiation Post-operative recurrence is common in uterine adenosarcomas. Recurrence occurs in the vagina and abdomen, is seen in up to 30% of cases resulting in a poor prognosis.

The presence and depth of the sarcoma’s myometrial invasion determines early staging diagnosis. The FIGO staging is IA: no myometrial invasion, IB: inner myometrial half, IC: outer myometrial half. If confined to the endometrium with no myometrial invasion, the prognosis is good with 7-13% recurrence for noninvasive tumors. FIGO stage II or greater is considered advanced with overall survival of 60% with myometrial invasion, but less than 50% if metastases are present. High grade adenosarcomas tend to have rapid recurrence. Adenosarcoma with myometrial invasion recurred in 36-46% of cases. Patients with sarcomatous overgrowth showed increased risk of recurrence, around 70-77 %, a risk of metastases around 40%, a decreased 5-year overall survival, 50 to 60 %; this is comparable to other high grade uterine sarcomas. Ovarian adenosarcoma is a rare tumor effecting the ovaries. 97.5 % of ovarian adenosarcomas are unilateral. It affects women of reproductive age 30-84, with a mean age of 54. Symptoms of ovarian adenosarcoma include abdominal swelling.

Tumor may present as adnexal mass. Most of the cases reported have associated endometriosis or an adenosarcoma arising from an endometriotic area, but the direct relation between this tumor and endometriosis has not been made clear in the literature. Ovarian adenosarcomas are surgically removed via salphingopherectomy or panhysterectomy. 67 % of patients had tumor rupture before excision. There is hormone therapy, or radiation therapy due to limited data. Ovarian adenosarcomas have a worse prognosis than uterine adenosarcomas because of the greater ease of peritoneal spread. Many of these ovarian tumors have caused problems in differential diagnosis. Advanced stage ovarian adenosarcoma is characterized by extraovarian spreading, sarcomatous overgrowth, tumor rupture; the presence of sarcomtous overgrowth is associated with increased risk of recurrence or extraovarian spreading. Recurrence poses more of a threat than metastases. 5 year survival is 64%, 10 year survival is 46%. Cervical adenosarcoma is an rare tumor that occurs most in women of reproductive age.

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André Soares Jardine is a Brazilian football manager in charge of the Brazil national under-20 team. Jardine was born in Porto Alegre, Rio Grande do Sul. After representing Grêmio's youth categories, he started studying Engineering but graduated in Physical Education at the Federal University of Rio Grande do Sul. Jardine joined Internacional in 2003, he took over all the club's youth categories during his ten-year stay, with his last team being the under-20s. On 24 September 2013, he returned to Grêmio after being named under-17 manager. On 27 July 2014, after Enderson Moreira's dismissal, Jardine was named interim manager, being in charge for one match before the appointment of Luiz Felipe Scolari. Subsequently, he was named assistant, but ended the year as the coordinator of the under-15s after having altercations with Scolari. In February 2015, Jardine was appointed at the helm of the under-20s, he was interim manager for two occasions before being named assistant in March 2018. On 11 November 2018, he was named interim until the end of the campaign, replacing sacked Diego Aguirre.

On 25 November 2018, Jardine was appointed manager of Tricolor for the 2019 season. The following 14 February, however, he was removed from his manager role, but was still kept at the club. On 3 April 2019, Jardine took over the Brazil national under-20 team. Official website André Jardine coach profile at Soccerway