Characteristics of ultrafine-ground potassium-bearing shale and the effects of roasting pre-cracking

Potassium-bearing shale is being developed as a potential alternative to potash for use in fertilisers. The first step in this process is to reduce its particle size by crushing. This paper explores whether roasting pre-cracked potassium-bearing shale can improve the quality of the resulting ultrafine product. Analysis of the particle size distribution of the ultrafine product and its fractal dimension found contradictory results: the minimum particle size distribution was obtained by roasting for 2.5 h, while the minimum fractal dimension was obtained by roasting for 1 h. Fuzzy comprehensive evaluation was conducted with three indicators—(1) the weight of the − 10 μm product, (2) the fractal dimension of the particle size distribution, and (3) d97—to obtain a unique combination of indicators that reflects the quality and quantity of the products. The weights of the three indicators were calculated by an analytic hierarchical process to be 0.69, 0.149 and 0.161, respectively. Roasting pre-cracked shale for 2–2.5 h was found to improve the mean values of the fuzzy comprehensive evaluation indicators by about 0.07. However, the cost increased from 2.82 RMB to ≥ 10.08 RMB, which is not feasible for widespread industrial implementation.

Pengembangan Aplikasi Ayo Kenal Pahlawanku Edisi Sulawesi Selatan

Hasil penelitian menunjukkan bahwa berdasarkan hasil validasi ahli, media Ayo Kenal Pahlawanku memenuhi kriteria sangat valid dengan rata-rata kevalidan produk sebesar 81,85%. Tingkat kepraktisan dan kemenarikan produk berdasarkan uji coba pengguna berturut-turut adalah 96,38% dan 94,39%, hal ini menunjukkan bahwa aplikasi media pembelajaran Ayo Kenal Pahlawanku memenuhi kriteria sangat praktis dan sangat menarik sehingga dapat digunakan tanpa revisi. Keefektifan diukur berdasarkan aktivitas peserta didik. Aktivitas peserta didik selama pembelajaran menggunakan media Ayo Kenal Pahlawanku pada saat uji coba lapangan memperoleh tingkat pencapaian 89,00%. Jika dikonversikan pada kriteria keaktifan hasil ini memenuhi kriteria sangat aktif sehingga produk dapat digunakan tanpa revisi. Berdasarkan seluruh hasil analisis produk meliputi kevalidan, kepraktisan, kemenarikan, dan keefektifan dapat disimpulkan bahwa aplikasi pembelajaran Ayo Kenal Pahlawanku ini sangat layak untuk digunakan sebagai suplemen pembelajaran materi Mengenal Pahlawan yang Ada di Indonesia. The results showed that based on the results of expert validation, Ayo Kenal Pahlawanku (Come to Know My Heros) media has met the very valid criteria with an average product validity of 81.85%. The level of practicality and attractiveness of the product based on user trials are 96.38% and 94.39%, respectively. This shows that Ayo Kenal Pahlawanku learning media application meets the criteria of being very practical and very interesting so that it can be used without revision. The effectiveness is measured based on the activities of students. Participants' activities during the training using Ayo Kenal Pahlawanku media during field trials learned from 89.00%. If the results on this activity criteria meet the very active criteria, the product can be used without revision. Based on the results of the product analysis which includes validity, practicality, attractiveness, and effectiveness, it can be said that Ayo Kenal Pahlawanku learning application is very feasible to be used as a learning supplement material for Knowing the Heroes in Indonesia.

The Effectiveness of Smart Learning Based on Expert Systems in Cryptography Courses

The development of science and technology requires universities not only to matter but also to have abilities in their respective fields including Security System. The unavailability of network design laboratory and its minimum, network design, cryptography design and flexibility of face-to-face time in the discussion of material compiled not in accordance with the competencies in this course. To overcome these deficiencies in learning activities, development of a project-based blended learning model is carried out. The development carried out in this study uses the Puslitjaknov development model which reduces the Borg and Gall stages to five stages namely product analysis, initial product design, expert validation and revision, field trials and implementation. Data were collected by interview, observation, questionnaire and test. Data were analyzed using quantitative and qualitative methods to produce research products in the form of books, modules, learning plans and manuals for the use of learning applications. Product validation by experts, practicality tests carried out by users and effectiveness tests with student learning outcomes. Based on the results of data analysis, the results of this study are: 1) Research has successfully developed a project-based blended learning model in Cryptography courses. 2) The developed learning model syntax consists of 9 stages / syntax. 3) In supporting learning activities, modules, RPS and manuals are used for learning applications. All products and models developed have been developed and are categorized as valid, practical and effective.

Aspects Regarding the Redesign of a Component of the Vertical Lifting Module Used in Sustainable Production Management

To remain competitive on the market with a developed product, it’s very important to analyze the manufacturing costs and times, from the concept stage of the product. Design for manufacturing and assembly (DFMA) is one of the engineering methods that can be applied to reduce manufacturing costs and times, right from the design stage, without compromising product performance and reliability. The 3D modeling of the tray was made in Solidworks, and for the analysis of it’s manufacture and assembly, the Boothroyd and Dewhurst principle and recommendations from the DFMA software were followed. This paper presents a case study for a subassembly called a tray, used in automatic vertical storage systems. For the redesigned model, substantial improvements were obtained, through cost reductions of 12% and an increase in design efficiency from 4.86 to 12.03. Product analysis using DFMA has proven to be a key point in the development of a product that meets engineers.

Chemical Transformation of α-Pinene derived Organosulfate via Heterogeneous OH Oxidation: Implications for Sources and Environmental Fates of Atmospheric Organosulfates

Organosulfur compounds are found to be ubiquitous in atmospheric aerosols — a majority of which are expected to be organosulfates (OSs). Given the atmospheric abundance of OSs, and their potential to form a variety of reaction products upon ageing, it is imperative to study the transformation kinetics and chemistry of OSs to better elucidate their atmospheric fates and impacts. In this work, we investigated the chemical transformation of an α-pinene derived organosulfate (C10H17O5SNa, αpOS-249) through heterogeneous OH oxidation at a relative humidity of 50 % in an oxidation flow reactor (OFR). The aerosol-phase reaction products were characterized using the high-performance liquid chromatography-electrospray ionization-high resolution mass spectrometry and the ion chromatography. By monitoring the decay rates of αpOS-249, the effective heterogeneous OH reaction rate was measured to be (6.72 ± 0.55) × 10−13 cm3 molecule−1 s−1. This infers an atmospheric lifetime of about two weeks at an average OH concentration of 1.5 × 106 molecules cm–3. Product analysis shows that OH oxidation of αpOS-249 can yield more oxygenated OSs having a nominal mass-to-charge ratio (m/z) at 247 (C10H15O5S−), 263 (C10H15O6S−), 265 (C10H17O6S−), 277 (C10H13O7S−), 279 (C10H15O7S−), and 281 (C10H17O7S−). The formation of fragmentation products, including both small OSs (C < 10) and inorganic sulfates, is found to be insignificant. These observations suggest that functionalization reactions are likely the dominant processes and that multigenerational oxidation possibly leads to formation of products with one or two hydroxyl and carbonyl functional groups adding to αpOS-249. Furthermore, all product ions except m/z = 277 have been detected in laboratory generated α-pinene derived secondary organic aerosols as well as in atmospheric aerosols. Our results reveal that OSs freshly formed from the photochemical oxidation of α-pinene could react further to form OSs commonly detected in atmospheric aerosols through heterogeneous OH oxidation. Overall, this study provides more insights into the sources, transformation, and fate of atmospheric OSs.

Consumer demand for novel fruit and vegetable products with extended shelf-lives in East Africa – a multinational multi-product analysis

Objective: To evaluate the potential of products made out of underutilized fruits and vegetables for closing seasonal nutritional gaps among rural and urban consumers in East Africa. Design: The multinational analysis combines sensory testing and experimental auctions to assess consumers’ perceptions and willingness to pay for six different fruit and vegetable products. Setting: Open markets in rural and urban areas in Kenya, Tanzania, and Uganda. Participants: There were 939 male and female adults who were at least 18 years old. Results: Tobit models for each product show that besides sensory perception, similar sociodemographic characteristics influence consumers’ willingness to pay for these products in all three countries. The products are especially liked among younger, male, and urban consumers. Conclusion: We conclude that there is demand and a market for processed fruit and vegetable products based on indigenous raw material in East Africa. The products, thus, have promising potential to improve nutrition, especially during off-season conditions when access to fresh produce is limited.

Enhanced removal of ibuprofen by heterogeneous photo-Fenton like process over sludge based Fe3O4-MnO2 catalysts

Heterogeneous photo-Fenton like catalysts with low cost, little hazardous, high effective and facile separation from aqueous solution were highly desirable. In this study, sludge-based catalysts combining nano Fe3O4-MnO2 and sludge activated carbon were successfully synthesized by high-temperature calcination method and then characterized. These synthetic materials were applied to remove ibuprofen in the heterogeneous photo-Fenton process. The preparation conditions of sludge-based catalysts optimized by orthogonal experiments were 2.0 M of ZnCl2, a temperature of 500 °C, a pyrolysis time of 60 min, and a sludge ratio: Fe3O4-MnO2 of 25:2. In batch experiments, the optimal experimental conditions were determined as catalyst dosage of 0.4 g·L−1, hydrogen peroxide concentration of 3.0 g·L−1, pH value of 3.3, and contact time of 2.5 h. The degradation rate Sludge/Fe3O4-MnO2 catalyst to ibuprofen is up to 95%. The removal process of ibuprofen fitted the pseudo-second-order kinetic model, and the photocatalytic degradation process was the main factor controlling the reaction rate. The catalytic mechanism was proposed according to the FTIR analysis and mass spectrometry product analysis, it was mainly attributed to the interaction between hydroxyl groups and benzene rings.

Study of SCC of X70 Steel Immersed in Simulated Soil Solution at Different pH by EIS

An electrochemical study of stress corrosion cracking (SCC) of API X70 steel in a simulated soil solution at different pH values (3, 8 and 10) was carried out. The stress conditions were implemented by slow strain rate stress test (SSRT) and the SCC process was simultaneously monitored by electrochemical impedance spectroscopy (EIS). Fracture surface analysis and corrosion product analysis were performed by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The results show that the susceptibility to SCC was higher as the pH decreases. In the acid solution, hydrogen evolution can occur by H+ and H2CO3 reduction, and more atomic hydrogen can diffuse into the steel, producing embrittlement. EIS results indicated that the anodic dissolution contributed to SCC process by reducing the charge transfer resistances during the SSRT test. While SEM micrographs shown a general corrosion morphology on the longitudinal surface of samples. At higher pH (pH 8 and pH 10), the SCC susceptibility was lower, which it is attributed to the presence of corrosion products film, which could have limited the process. Using the angle phase (φ) value it was determined that the cracking process started at a point close to the yield strength (YS).