Efforts to fulfill food security to anticipate population growth in Indonesia need to be supported by universities through research and community service. The application of the Natural Animal Audio Organic Growth System (NA-AOGS) with a STEM (Science, Technology, Engineering, and Mathematics) approach is an effort to help the community increase crop yields and accelerate the growth of soybeans (Glycine max (L.) Merill). The research method used is R&D (Research & Development) which is modified from Cennamo and Kalk (2018). This model is in the form of a spiral cycle using 5 (five) main activities as follows: (1) defining the product conceptual; (2) designing research products; (3) demonstrating the product in a limited trial; (4) developing the product through the process of evaluating the test results, and (5) presenting the product to the public. The direct impact of learning is the improvement of science process skills and critical thinking of students participating in the Biophysics course at the Natural Sciences Study Program, Universitas Negeri Yogyakarta. This is due to the effective application of STEM to link science learning with contextual technology and engineering (NA-AOGS), environmentally friendly technology (only using natural animal sound frequency variables), mathematical elements in data analysis, and analysis of soybeans plant growth charts. The economic impact of this research is the scientific contribution in the form of adaptation of agricultural technology so that it can increase soybean yields (an increase of 130.38% on an area of 2750 m2). The novelty and contribution of this research is the integration of science learning with agricultural techniques and technology with a STEM approach so that it can improve the welfare of farmers in educational institutions as a new model in science learning.
The objective of this study is to design a temperature measurement system based on a non-contact method using a sensor camera from a webcam. The material being measured is nickel wire given an electrical current of 4.5 A–6.5 A with an interval of 0.5 A. The temperature measurement is based upon the measurement of the average pixel value distribution of infrared (IR) electromagnetic waves emitted by the measured material, i.e.: the nickel wire. The IR waves are passed through a diffraction grating and then captured by the sensor camera consisting of red, green, and blue layers. Calculation of the temperature is conducted by way of Planckian distribution as a model for the average pixel value distribution in the IR regions producing Wien’s displacement law. Results show that the IR wavelength at maximum average pixel value shifts to a shorter wavelength as the nickel wire is heated in accordance with Wien’s displacement law. Moreover, the Wien’s constant is recovered for the temperature calculation of the red and green layers, which shows the best model for the non-contact measurement system. However, the temperature measurement still contains a systematic error that shifts the calculated temperature in contrast to the true temperature. This systematic error may be reduced by adjusting the measurement system set-up.
Carbon nanodots (Cdots) have many unique properties such as luminescence that can be utilized in various fields. The purposes of this study are to synthesize Cdots from kangkung (Ipomoea aquatica) through frying and roasting techniques and compare the optical properties of the Cdots using UV-Vis, PL, and FTIR. Three stages of synthesizing process of Cdots, i.e.: preparing the kangkung powder (root, stem, leaf) and synthesizing the Cdots through frying and roasting techniques. Each part (root, stem, and leaf) was heated in an oven at 250 oC for 2 hours and mashed into powder. The frying method was done by frying 15 g of the powder in 120 ml oil for 5 minutes at 88 oC, filtered, and dissolved in n-hexane. In addition, the roasting method was done by frying the powder without oil as much as 15 g for 5 minutes, dissolved in 120 ml of distilled water, and then filtered. The UV-Vis characterization showed one absorbance peak for Cdots via frying and roasting techniques at 293 nm to 296 nm and 262 nm to 282 nm, respectively. The Cdots through frying and roasting techniques produce red and green luminescence, respectively. The FTIR characterization showed the presence of C=C and C=O functional groups, which are the core and surface state of the Cdots by frying technique, while the samples via roasting technique showed only the core. It can be concluded that the Cdots samples obtained from frying and roasting methods have different optical properties. The frying method produces Cdots with longer wavelength at the absorbance peak in the UV-Vis test compared to the roasting method. Moreover, the frying and roasting methods produce different color luminescence.
Penelitian ini bertujuan untuk mensintesis, mengkarakterisasi, dan mengetahui peran nanomaterial carbon-dots (Cdots) sebagai antibakteri terhadap bakteri S. mutans dan E. coli. Cdots dibuat dengan bahan dasar daun sirih (Piper Betle L.) menggunakan metode pemanasan oven. Terdapat tiga buah sampel Cdots yang dihasilkan yaitu 0,5 g serbuk daun sirih+aquades (Cdots A), 0,5 g serbuk daun sirih+ekstrak daun sirih (Cdots B), dan 1 g serbuk daun sirih+ekstrak daun sirih (Cdots C). Ketiga sampel memiliki karakteristik yang hampir sama, yaitu adanya puncak absorbansi pada rentang panjang gelombang 257nm – 320 nm. Daya serap yang tinggi pada rentang ultraviolet (UV) merupakan salah satu sifat yang dimiliki Cdots. Selain itu, ketiga sampel Cdots memiliki pendaran biru-kehijauan (cyan) ketika dikenai laser UV.Hal ini merupakan sifat luminesensCdots yang dapat berpendar pada panjang gelombang cahaya tampak. Cdots tersusun dari core dan surface state yang masing-masing ditunjukkan dengan adanya gugus fungsi C=C dan gugus O-H serta C-O yang terdeteksi oleh uji FTIR dari ketiga sampel Cdots. Pengujian antibakteri menggunakan metode Kirby-Bauer menunjukkan sampel Cdots C memiliki aktivitas antibakteri tertinggi karena memiliki konsentrasi Cdots yang lebih banyak dan bekerja sama dengan ekstrak sirih yang memiliki sifat antibakteri sehingga berpotensi sebagai agen antibakteri dibandingkanekstrak daun sirih murni.
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