Judul: Toxicity Nitrite on Physiological Responses of Day of Culture 30 Vannamei Shrimps Litopenaeus vannamei
Abstrak: Nitrit-N merupakan bentuk nitrogen yang relatif bersifat tidak stabil dan dapat teroksidasi serta terbentuk dari proses nitrifikasi. Nitrifikasi merupakan proses oksidasi amonia (NH3-N) menjadi nitrit-N (NO2-N) dan nitrat-N (NO3-N). Konsentrasi nitrit-N yang tinggi dalam suatu perairan bersifat toksik bagi udang vaname dan menyebabkan stres hingga kematian. Penelitian ini bertujuan untuk mengukur toksisitas nitrit-N dalam lingkungan perairan terhadap produktivitas dan respons fisiologis udang vaname Litopenaeus vannamei DOC 30. Penelitian ini terbagi menjadi tiga tahap, yaitu uji pendahuluan, uji letal, dan uji subletal dengan menggunakan metode rancangan acak lengkap (RAL). Pengamatan mortalitas hewan uji dilakukan pada jam ke-24, 48, 72, dan 96. LC50 pemaparan nitrit-N selama 96 jam pada udang vaname ukuran DOC 30 adalah 88,88±28,35 mg L-1NO2-N. Konsentrasi nitrit-N pada penelitian ini menunjukkan penurunan seiring dengan lama waktu pemaparan nitrit-N. Pemaparan nitrit-N dengan konsentrasi 45 mg L-1 pada udang vaname DOC 30 dapat menekan survival rate mencapai 55,33±4,04%, penurunan pertumbuhan panjang mutlak sebesar 79,80 %, dan penurunan pertumbuhan bobot mutlak sebesar 85,70%, serta peningkatan respons fisiologis (Total hemocyte count, glukosa darah, dan kolesterol), Nitrite-N is a form of nitrogen that is relatively unstable and easily oxidized which is made up of the nitrification process. Nitrification is the process of ammonia (NH3-N) oxidation that turns into nitrite-N (NO2˗N) and nitrate-N (NO3- N). The high concentration of nitrite-N in particular water is toxic for the vannamei shrimps, and it causes stress to death. This research aims to measure the nitrite-N concentration in the water environments toward product as well as the physiological response of DOC 30 vannamei shrimp Litopenaeus vannamei. This research is divided into three steps, which are preliminary, lethal, and sub-lethal tests by using a completely randomized design method. The observation of the mortality of tested animals was conducted at the 24th, 48th, 72nd, and 96th hours. LC50 of the nitrite-N exposure for 96 hours at DOC 30 vannamei shrimps is 88,88±28,35 mg L-1 NO2-N. Nitrite-N concentration in this research showed the decline along with the duration of nitrite-N exposure. Nitrite-N exposure with the concentration of 45 mg L-1 in the DOC 30 vannamei shrimp can press of survival rate values until 55,33±4,04%, decline absolute length growth by 79,80 %, decline absolute weight growth by 85,70%, and increased physiological response (Total hemocyte count, glucose, cholesterol). Keywords: LC50, Litopenaeus vannamei, nitrite-N
Keyword: LC50, Litopenaeus vannamei, nitrite-N, stress, toxic

Judul: Toxicity of Total Ammonia Nitrogen (TAN) Exposure to Productivity and Physiological Responses of Day of Culture 30 Litopenaeus vannamei
Abstrak: Total Ammonia Nitrogen (TAN) berasal dari sisa metabolisme organisme (feses), bahan organik, sisa pakan, dan bangkai organisme maupun mikroorganisme dalam perairan. TAN merupakan suatu senyawa anorganik yang terdiri dari amonia terionisasi (NH4+) dan amonia tidak terionisasi (NH3). Senyawa amonia yang toksik bagi organisme perairan yaitu NH3. Tujuan dari penelitian yaitu untuk menentukan konsentrasi akut amonia yang diekspresikan oleh nilai LC50 dan menganalisis pengaruh toksisitas amonia terhadap produktivitas serta respons fisiologis udang vaname pada salinitas 15 g L-1. Penelitian dilakukan dengan menggunakan tiga uji diantaranya uji pendahuluan, uji letal dan uji subletal. Kadar TAN sebesar 103,05 mengandung NH3 sebesar 4,37 mg L-1 dalam perairan bersalinitas 15 g L-1 dapat membunuh 50% dari populasi udang vaname dalam jangka waktu 96 jam serta adanya amonia sebesar 10 sampai 52 mg L-1 dapat menurunkan tingkat produktivitas (SR, Pertumbuhan Bobot Mutlak dan Pertumbuhan Panjang Mutlak) dan meningkatkan respons fisiologis (THC, Glukosa dan Kolesterol) dari udang vaname DOC 30, Total Ammonia Nitrogen (TAN) is formed by the metabolic waste of organism (feces), organic matter, feed waste, and cardaver of organism or microorganism in the media of aquaculture. TAN is an inorganic compounds consists of ionized ammonia (NH4+) and unionized ammonia (NH3). TAN compounds that are toxic to aquatic organisms are NH3. The aim of this research was to specify the acute concentration of ammonia expressed by the value of LC50 and observe the impact of TAN toxicity in productivity and physiological responses of vannamei shrimp Litopenaeus vannamei in salinity 15 g L-1. This research was done with compeletely randomized design with 3 test which were preliminary, lethal, and sub lethal test. TAN levels of 103,05 containing NH3 of 4,37 mg L-1 in water with a salinity of 15 g L-1 killed 50% of the vaname shrimp population within 96 hours and the presence of ammonia of 10 to 52 mg L-1 reduced the productivity levels (SR, Growth of Absolute Weight and Growth of Absolute Length) and increased the physiological responses (THC, glucose and cholesterol) of DOC 30 vaname shrimp
Keyword: ammonia, LC50, stress, toxicity, vanname shrimp

Judul: : Persamaan Tunggal sebagai Representasi Kurva Komposit
Abstrak: A mathematical method is introduced to represent a composite curve based on an extension of analytic geometry. The representation is given either with a single equation or with two equations, in the case of parametric representation. This method permits the representation of composite curves in similar manner to the conventional representation of non-composite curves. Some mathematical tools, including Heaviside unit step function and periodizer function, are used in the establishment of a single equation. In this paper, regular equations of regular and irregular polygon, as well as composite curves of two dimensions, are implemented using a computer algebraic system, Mathematica.
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