Garuda - Garba Rujukan Digital

p-Index From 2019 - 2024

2.286

P-Index

This Author published in this journals

All Journal Jurnal Rekayasa Proses Jurnal MEKANIKAL Reaktor International Journal of Science and Engineering (IJSE) TEKNIK Jurnal Kesehatan Lingkungan indonesia JURNAL TEKNOLOGI KIMIA DAN INDUSTRI Prosiding Seminar Nasional Sains Dan Teknologi Fakultas Teknik Bulletin of Chemical Reaction Engineering & Catalysis Majalah Ilmiah MOMENTUM Emerging Science Journal Indonesian Journal of Chemistry JURNAL PANGAN Jurnal Pasopati : Pengabdian Masyarakat dan Inovasi Pengembangan Teknologi Bulletin of Chemical Reaction Engineering & Catalysis

Ratnawati Ratnawati

Department Of Chemical Engineering Faculty Of Engineering Diponegoro University

Author-ID : 2956117

Aerospace Engineering Agriculture, Biological Sciences & Forestry Automotive Engineering Chemical Engineering, Chemistry & Bioengineering Chemistry Civil Engineering, Building, Construction & Architecture Computer Science & IT Control & Systems Engineering Earth & Planetary Sciences Education Electrical & Electronics Engineering Energy Engineering Environmental Science Industrial & Manufacturing Engineering Materials Science & Nanotechnology Mechanical Engineering Public Health Social Sciences

Published : 40 Documents Claim Missing Document

Claim Missing Document

Articles

1 2 3 4

Perubahan Kualitas Beras Selama Penyimpanan (Change of Rice Quality During Storage) Ratnawati, Ratnawati; Djaeni, Mohamad; Hartono, Damin
JURNAL PANGAN Vol 22, No 3 (2013): PANGAN
Publisher : Perum BULOG

Penyimpanan merupakan tahap yang menentukan dalam menjamin ketersediaan beras berkualitas. Selama penyimpanan, beras mengalami penyusutan kualitas dan kuantitas yang disebabkan oleh perubahan fisik, kimia, dan biologi. Penelitian ini bertujuan untuk mengamati perubahan kualitas beras selama penyimpanan. Aspek yang diamati adalah kadar air, butir kepala, menir, patah, dan kuning, serta water uptake dan pertumbuhan kutu beras (Sitophilus oryzae). Dalam penelitian ini digunakan tiga jenis beras, yaitu yang mendekati SNI Mutu III (jenis A) dan IV (jenis B), serta yang tidak memenuhi standar SNI (jenis C). Beras ditempatkan dalam karung plastik berisi 15 kg dan disimpan pada keadaan ambient (temperatur 29–32°C dan kelembaban 65–95 persen). Kualitas beras diamati setiap 15 hari, sedangkan pertumbuhan kutu diamati setiap minggu. Hasil menunjukkan bahwa kadar air beras jenis A dan B, dengan nilai awal < 13,5 persen, mengalami kenaikan 0,03 persen/hari sampai mendekati 14,5 persen, sementara jenis C, dengan kadar air awal 15,5 persen, relatif konstan. Beras berkadar air > 14 persen mengalami degradasi akibat reaksi Maillard dan penjamuran yang mengakibatkan warna kuning, penurunan water uptake, serta meningkatnya butir patah dan menir. Selain itu, populasi kutu meningkat dengan kecepatan 3 ekor/100g beras/minggu. Kesimpulan dari penelitian ini adalah kadar air beras yang disimpan harus < 14 persen, dan kelembaban udara di unit penyimpan harus dijaga serendah mungkin (< 65 persen).Storage is a crucial stage in ensuring the availability of quality rice. During storage, rice quality and quantity decrease as a cause of changes in physical, chemical, and biological processes. This study is aimed to observe the changesb of rice quality during storage. The quality components measured are moisture content, whole kernel, broken kernel, chips, yellow kernel, water uptake, and the growth of rice weevil (Sitophilus oryzae). Three types of rice are used, namely that meet SNI Quality III (type A) and IV (type B), and that does not meet SNI standard (type C). The rice is placed in plastic bags with 15 kg of rice in each bag and stored at ambient conditions (29–32°C and relative humidity of 65–95 percent). Quality of the rice is observed every 15 days, while the growth of weevil is observed every week. The results show that moisture content of rice types A and B, with initial value < 13.5 percent, increases with a rate of 0.03 percent/day, while type C, with initial moisture content of 15.5 percent, is relatively constant. The increase of moisture content causes the rice to be degraded due to the Maillard reaction and mould that yield yellowing, decrease of water uptake, and increase of broken kernel as well as chips. It is also observed that the number of weevil increases during storage with the growth rate of 3 weevils/100g of rice/week. The conclusion of this research is that the initial moisture content of rice to be stored should be < 14 percent, and the humidity of the air in storage room must be kept as low as possible (< 65 percent).

APPLICATION OF EPOXY RESIN COMPOSITE WITH FIBER IMPERATA CYLINDRICA FOR MULTI PURPOSE VAN CAR BUMPER Leonard, Johannes; Ratnawati, Ratnawati
Jurnal MEKANIKAL Vol 6, No 2 (2015): JM Vol. 6 No. 2 Juli 2015
Publisher : Jurnal MEKANIKAL

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (469.415 KB)

Penelitian ini bertujuan menganalisis degan menggunakan metode statistik SPSS dengan aplikasi regresi dan Varian Anova, dimana spesimen dibuat dari serat alang-alang (Imperata cylindrica) Â dan resin epoksi dengan perbandingan komposi 60:40%,65:35%, dan 70:30%, dan ditambah pengeras hardener 4% . Dapat disimpulkan bahwa variasi komposisi serat alang-alang (Imperata cylindrica) berpengaruh terhadap uji statistik analisis Regresi dan varian Anova bumper depan kendaraan Multi Purpose van. Yaitu komposisi 60:40%Â koefisienya sebesar -1,035 berarti dapat digunakan sebagai bumper kendaraan Van serbaguna.

Modifikasi Pati Sukun (Artocarpus Altilis) dengan Teknik Oksidasi Menggunakan Hidrogen Peroksida Tanpa Katalis Budiyati, Catarina Sri; Kumoro, Andri Cahyo; Ratnawati, Ratnawati; Retnowati, Diah Susetyo
TEKNIK Vol 37, No 1 (2016): (Juli 2016)
Publisher : Diponegoro University

Salah satu sumber bahan pangan lokal yang belum banyak dimanfaatkan adalah buah sukun (Artocarpus Artilis) yang cukup banyak terdapat di Indonesia. Akan tetapi, pemanfaatan buah sukun terkendala pada kurangnya daya simpan buah segar. Oleh karena itu, perlu dilakukan upaya untuk meningkatkan pemanfaatan buah sukun dengan mengolahnya menjadi produk yang lebih luwes dengan daya simpan yang lebih baik, yaitu menjadi pati sukun. Sifat-sifat pati sukun perlu diperbaiki agar dapat digunakan sebagai pengganti tepung terigu. Tujuan dari penelitian ini adalah untuk memodifikasi pati sukun dengan cara oksidasi menggunakan larutan hidrogen peroksida. Dalam penelitian ini dikaji pengaruh konsistensi luluhan, konsentrasi hidrogen peroksida, waktu, dan suhu terhadap karakteristik fisikokimia pati sukun teroksidasi yang dihasilkan dan ditentukan kondisi optimalnya. Hasil penelitian menunjukkan bahwa semua variable yang dikaji tersebut mempengaruhi reaksi oksidasi pati sukun. Oksidasi pada konsistensi luluhan 20%, konsentrasi hidrogen peroksida 2% dan suhu 50Â°C mampu menghasilkan nilai swelling power dan water solubility yang terbaik. Reaksi oksidasi tidak mengubah struktur dan morfologi pati sukun termodifikasi secara signifikan. Â [Title: Modification of Breadfruit (Artocarpus altilis) starch through non-catalytic hydrogen peroxide oxidation] One of local source of food that has not been intensively explored is breadfruit (Artocarpus Artilis). However, the utilization of breadfruit is limited by the poor storage properties of the fresh fruit. Therefore, efforts should be made to improve the utilization of breadfruit to process it into more flexible products with better storability, suach as breadfruit starch. Breadfruit starch properties need to be improved so that it can be used to substitute wheat flour. The aim of this study was to modify the breadfruit starch by oxidation using hydrogen peroxide solution. This work studied examined the influence of consistency of starch slurry, hydrogen peroxide concentration, time, and temperature on the physicochemical properties of the oxidized breadfruit starch. The optimal conditions were also determined. The results showed that all of these variables affected the oxidation of starch breadfruit. The oxidation on starch slurry with consistency 20%, the concentration of hydrogen peroxide of 2%, and temperature of 50Â°C produced modified starch with best swelling power and water solubility. The oxidation did not significantly change the structure and morphology of the modified starch.

RECOVERY GARAM LITHIUM DARI AIR ASIN (BRINE) DENGAN METODA PRESIPITASI Sumarno, Sumarno; Ratnawati, Ratnawati; A. Nugroho, A. Nugroho
TEKNIK Volume 33, Nomor 2, Tahun 2012
Publisher : Diponegoro University

Lithium demand increases as it is widely used as raw material for rechargeable battery, alloy for airplane, andfuel for fusion nuclear reactor. Lithium is an extremely reactive element, that it is never found as free element innature. Lithium compounds are found in earth crust, with very small concentration (20 â€“ 70 ppm) and totalcontent of more than 20 million tons. The biggest lithium reserve is in seawater (0,14 â€“ 0,25 ppm) andgeothermal water (7 ppm) with total amount of 230 billion tons. There is no industry applies the technology torecover lithium from seawater. Having a vast sea area and abundant geothermal sources, Indonesia needs todevelop a technology to recover lithium from both sources. This research is aimed to recover lithium fromgeothermal water. The experiment was conducted using synthetic and geothermal water with lithiumconcentration range of 220 â€“ 400 ppm, temperature range of 20 â€“ 40Â°C, and mixing time range of 1 â€“ 4 hours.The experiment was designed with 2 level factorial design. The results show that the most influencing variable ismixing time, while significant interaction amongst variables is not observed. Further experiment usinggeothermal water from Bledug Kuwu with initial lithium concentration of 400 ppm and temperature 30Â°Cresulted in optimum mixing time, i.e. 3 hours with 92,5% of the lithium could be recovered

KONVERSI ELEKTROKIMIA AMONIA MENJADI HIDROGEN Ratnawati, Ratnawati; Sumarno, Sumarno; Nugroho, Amin
TEKNIK Volume 31, Nomor 2, Tahun 2010
Publisher : Diponegoro University

One of the most dangerous pollutants in wastewater is ammonia. The concentration of ammonia inwastewater discharged from nitrogen fertilizer industry is up to 1500 ppm. Ammonia can be removed byseveral methods such as biological denitrification, air-stripping, and ion exchange. The methods cannotreduce the concentration of ammonia to a low level as required for standard quality of wastewater. Theelectrochemical method has recently attracted attention for the treatment of wastewater containing ammonia.This research is aimed to evaluate the effect of ammonia concentration, current density, and time on theelectrolysis process. Synthetic wastewater containing 500-1500 ppm of ammonia was used in this research.The solution was electrolyzed in a electrolytic cell with Pt/SS electrodes. The experiment was conducted byvarying current density in the range of 5 â€“ 10 mA/cm2 and time from 0 to 105 minutes. The experiment resultsshow that as current density rises, the electrolytic reaction occurs more rapidly. On the other hand, initialconcentration of ammonia has negative effect on the final conversion of ammonia.

Hubungan Pengetahuan, Perilaku dan Lingkungan Rumah dengan Kejadian Transmisi Tuberkulosis Paru di Wilayah Kerja Puskesmas Bandarharjo Semarang Zulaikhah, Siti Thomas; Ratnawati, Ratnawati; Sulastri, Neng; Nurkhikmah, Eli; Lestari, Novi Dian
Jurnal Kesehatan Lingkungan Indonesia Vol 18, No 2 (2019): Oktober 2019
Publisher : Master Program of Environmental Health, Faculty of Public Health, Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/jkli.18.2.81-88

Latar belakang: Tuberkulosis paru adalah penyakit menular yang disebabkan oleh bakteri mycobacterium tuberculosis masih menjadi masalah kesehatan. Tingginya angka kejadian TB paru dapat dikarenakan adanya faktor tingkat pengetahuan yang rendah, perilaku kesehatan yang buruk dan lingkungan rumah seperti ventilasi, pencahayaan, kelembaban, kepadatan hunianyang tidakmemenuhi syarat. Tujuan penelitian ini untuk mengetahui variabel paling dominan berhubungan dengan transmisi kejadian TB paru di Wilayah Kerja Puskesmas Bandarharjo Kota Semarang.Metode: Desain penelitian observasional dengan pendekatan case control. Subjek penelitian terdiri dari 40 kasus dan 40 kontrol. Kasus merupakan penderita TB paru di Puskesmas Bandarharjo yang didiagnosis secara klinis dan laboratorik BTA positif dan tercatat dalam medical record dari bulan Agustus 2016 sampai Agustus 2017,kontrol merupakan tetangga kasus yang tidak terdiagnosis TB paru BTA positif dan anggota keluarga tidak menderita TB paru BTA positif. Teknik sampling menggunakan proporsional random sampling. Data yang terkumpul dianalisis dengan uji univariat menggunakan distribusi frekuensi, uji bivariat menggunakan Chi Square, uji Multivariat menggunakan Regresi logistik ganda. Hasil : Hasil uji bivariat variabel lingkungan yang terdiri dari luas ventilasi (p=0,000); kepadatan hunian (p=0,000); kelembaban (p=0,001); pencahayaan (p=0,001); suhu (p=0,001), sedang hasil variabel pengetahuan (p=0,002) dan perilaku (p=0,005). Hasil analisis multivariat variabel pengetahuan (OR=3,776); kepadatan hunian (OR=4,476); kelembaban (OR=4,030); pencahayaan (OR=3,635); suhu (OR=3,064); pengetahuan (OR=6,374); perilaku (OR=3,525).Simpulan: Lingkungan rumah, pengetahuan dan perilaku berhubungan dengan kejadian TB paru di wilayah kerja puskesmas Bandarharjo Semarang dan faktor yang paling dominan berhubungan adalah pengetahuan.Â ABSTRACTTitle: Relationship Knowledge, Behavior and Household Environmentwith the Transmission Insidence Pulmonary Tuberculosis in the Work Area of Bandarharjo Health Center SemarangBackground: Pulmonary tuberculosis, an infectious disease caused by the bacterium Mycobacterium tuberculosis remains a health problem. A higher incidence of pulmonary TB has been associated with low level of knowledge, poor health behavior and household environment such as ventilation, lighting, humidity, residential density. The purpose of this study was to identify the most dominant factor associated with the transmission pulmonary TB in the Bandarharjo Health Center in Semarang.Methods: The research was an observational one with a case control study. The case and the control of this research were both using 40 respondents. The case was patients clinically diagnosed with pulmonary TB and has a laboratory BTA+ and documented in the medical record from August 2016 to August 2017. The control was a neighbor of cases with no BTA+ (acid resistant bacilli) pulmonary TB and history of family no BTA+ of pulmonary TB. The proportional random sampling was applied. The collected data were analyzed using univariate test of frequency distribution, bivariateof Chi Square, multivariate oflogistic regression.Results: Bivariate test of environmental variables consisting of ventilation area (p = 0.000); occupancy density (p = 0.000); humidity (p = 0.001); lighting (p = 0.001); temperature (p = 0.001), while the results of the knowledge variable (p = 0.002) and behavior (p = 0.005). The multivariate analysis showed variable of knowledge (OR = 3.776); residential density (OR = 4.476); humidity (OR = 4.030); lighting (OR= 3.635); temperature (OR = 3.064); knowledge (OR = 6.374); behavior (OR = 3.525).Conclusion: The household environment, knowledge and behavior were related to the transmission incidence of pulmonary tuberculosis in the working area of Bandarharjo health center and the most dominant factor was knowledge.

Response Surface Methodology for Formulating PVA/Starch/Lignin Biodegradable Plastic Ratnawati Ratnawati; Retno Wulandari; Andri Cahyo Kumoro; Hadiyanto Hadiyanto
Emerging Science Journal Vol 6, No 2 (2022): April
Publisher : Ital Publication

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.28991/ESJ-2022-06-02-03

The use of petroleum-based plastics has raised environmental issues as more plastic waste enters and accumulates in the environment. It has led to the development of biodegradable plastics. Starch is one of the potential materials to make biodegradable plastic, but starch-based plastic has poor mechanical strength. Blending starch with poly(vinyl alcohol) (PVA) and lignin is expected to improve the mechanical properties of the plastic. Biodegradable plastic films from PVA/starch/lignin blends with glycerol as a plasticizer were prepared using an internal mixer for compounding and a hot press molding machine for film making. The percentage of lignin (2-10%), glycerol (25-65%), and mixing temperature (190-230 oC) were varied according to the three levels of the Box-Behnken design. The ANOVA evaluation revealed that glycerol had the most significant effect on the mechanical properties of the film. Then, three models for the estimation of tensile strength, elongation at break, and tear resistance were developed. As expected, the models satisfactorily predict the effect of all input variables on the response variables. The optimum conditions for preparing the film were acquired from the equations, namely 197.6 oC for the temperature, 10% for lignin, and 45.1% for glycerol. The biodegradable plastic prepared using the optimum conditions possessed a tensile strength of 8.46 ± 1.08 MPa, an elongation at break of 139.00 ± 8.59%, and a tear resistance of 69.50 ± 2.50 N/mm. These values are in good agreement with the predicted values. Doi: 10.28991/ESJ-2022-06-02-03 Full Text: PDF

Pembuatan dan Karakterisasi Sabun Susu dengan Proses Dingin Diah S. Retnowati; Andri C. Kumoro; Ratnawati; Catarina S. Budiyati
Jurnal Rekayasa Proses Vol 7, No 2 (2013)
Publisher : Departemen Teknik Kimia Fakultas Teknik Universitas Gadjah Mada

Pada penelitian ini, sabun susu dibuat dari larutan susu-NaOH dengan campuran minyak yang terdiri dari minyak sawit, minyak kelapa, minyak jarak dan minyak canola. Tujuan penelitian adalah mempelajari pengaruh perbandingan massa minyak kelapa terhadap minyak canola dan konsentrasi asam sitrat terhadap pH sabun, kekerasan sabun, kemampuan pembentukan busa dan derajat kebersihan. Percobaan dilakukan dengan menuangkan larutan susu-NaOH dan asam sitrat ke dalam campuran minyak dengan perbandingan berat tertentu dan diaduk dengan kecepatan 400 rpm. Setelah terjadi trace (jejak putaran pada larutan) larutan tersebut dicetak dan didiamkan selama 24 jam. Produk sabun dianalisis kekerasan, pH, kemampuan pembentukan busa dan derajat pembersihan setelah dilakukan proses pemeraman selama 4 minggu. Hasil penelitian menunjukkan bahwa 2% massa asam sitrat dapat menurunkan pH sabun dari 10,2 menjadi 9,8, tetapi juga menurunkan tingkat kekerasan, kemampuan pembentukan busa dan kemampuan membersihkan. Perubahan rasio massa minyak kelapa terhadap minyak canola dari 0,5-2, hanya berpengaruh terhadap kekerasan sabun. Kata Kunci: sabun susu, proses dingin, pH, kekerasan, tingkat kebersihan, pembentukan busa In this research, cold process was chosen to make soap from lye (NaOH solution) and mixture of palm, coconut, castor, and canola oils with certain ratio. This conducted research is to study the effect of palm to canola oil mass ratio and citric acid concentration on pH, hardness, foaming capacity and the cleansing power of the soap. The soap formation was first conducted by dissolving NaOH in the milk with certain concentration sufficient for the oil mixture saponification. The solution and citric acid solution were then added to the oil mixture and was stirred at 400 rpm. After trace occurred, the mixture was transferred to a mold and then was put in an open space for 24 hours. The soap was taken out from the mold and was cured for 4 weeks. The hardness, pH, the foaming capacity, and the cleansing power of the resulted soap were analyzed. The result show that the addition of 2% of citric acid reduces the pH of the soap from 10.2 to 9.8, the hardness, the foaming capacity, and the cleansing ability of the soap. The variation of the ratio of the mass of coconut to canola oil from 0.5 to 2 affects only the hardness of the soap. Keywords: milk-soap, cold process, pH, hardness, cleansing power, lathering

Ultrasound-Assisted Ultra-Mild-Acid Hydrolisis of -Carrageenan Ratnawati Ratnawati; Nita Indriyani
Reaktor Volume 17 No. 4 Desember 2017
Publisher : Dept. of Chemical Engineering, Diponegoro University

The low molecular weight fraction of κ-carrageenan is useful in biomedical applications. An ultrasound-assisted acid hydrolysis of κ-carrageenan has been studied. κ-carrageenan with an initial number-average molecular weight of 629 kDa was dispersed in distilled water to form a 5 g/l solution. The pH (3 and 6) of the solution was adjusted by adding HCl solution. The depolymerization reaction was carried out in an ultrasonic device at various temperatures (30, 40, 50, and 60°C) and times (8, 16, 24, and 32 min). The experimental results showed that ultrasound positively contributed to acid hydrolysis process. The number-average molecular weight of the treated k-carrageenan was lower or the percentage of reduction was higher at lower pH, longer reaction time, and higher temperature. The lowest number-average molecular weight (14 kDa) or the highest percent of molecular weight reduction reduction (97.7%) was achieved after ultrasonic irradiation at 60°C and pH 3 for 32 min. Keywords: depolymerization; midpoint scission; ultrasonication

NANOTECHNOLOGY AN EMERGING NEW TECHNOLOGY FOR INDONESIA PART I. NANOTECHNOLOGY IN GENERAL Ratnawati Ratnawati; anggoro D.D. Anggoro; G.A. Mansoori G.A. Mansoori
Reaktor Volume 10 No. 1 Juni 2006
Publisher : Dept. of Chemical Engineering, Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/reaktor.10.1.46-53

Nanotechnology is shortly defined as the ability to build micro and macro material and product with atomic precistion. Feynman is considered to be the scientist who put a strong foundation for the development of nanotechnology with his phenomenal speech in 1959 entitled "There's Plenty of Room at the Bottom - An invitation to enter a new field of physics." The invention of scanning tunneling microscope, followed by atomic force microscope, has enabled the world to see atoms and nolecules and opened more possibility for the scientists to develop nanotechnology. Other breakthough in nanotechnology is the discoveries of fullerene, carbon nanotube and diamondoids. Nanotechnology has found various fields of application, such as in biomedical , materials, aerospace, surface science and energy, to name a few, lead by the united States, Europe, and Japan, The technology brings benefits as well as risks to human life. Some of the risks are potentially global in scope. It is why a single, trustworthy, international administration holding controls on the technologyis is urgently needed.

Co-Authors . Widayat A. Nugroho A. Nugroho Aat Zaki Mubarok Affian Widjanarko Affian Widjanarko Aji Prasetyaningrum Amin Nugroho Andri C. Kumoro Andri Cahyo Kumoro anggoro D.D. Anggoro Anita Pinalia Aprilina Purbasari Bakti Jos Bayu Prianto Catarina S. Budiyati Catarina Sri Budiyati Cindi Yasintasia Dewi Ayuningtyas Diah S. Retnowati Diah Susetyo Retnowati Djoko Mulyono Dyah Arum Kusumaningtyas Dyah Hesti Wardhani Fadlillah Fani Fitri Lafifa G.A. Mansoori G.A. Mansoori Gian Restu Prinanda H Hadiyanto Hargono Hargono Hartono, Damin Henny Setyaningsih Jefri Chandra Runanda Johannes Leonard Jumali Jumali L. Buchori Lestari, Novi Dian Luqman Buchori M. Djaeni Maharani Ratridewi Maria Augustine Graciafernandy Nafiah Amalia Nita Indriyani Nita Indriyani Noer Abyor Handayani Noor Hidayati Nur Rokhati Nurfiningsih Nurfiningsih Nurkhikmah, Eli Nurul Asiah Nurul Asiah Prawita Dhewi Purbo Suseno R Ridwan R. Ridwan Retno Wulandari Rizky Adi N Sadam Arrois Siti Thomas Zulaikhah Suherman Suherman Sulastri, Neng Sumarno . Teguh Riyanto Utami Diah P. Wiratno Wiratno Yudhy Dharmawan Yustina Linasari

Title Search

Found 40 Documents Search

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Title

Found 40 Documents
Search