Mechanical Activation of Smectite-Based Nanocomposites for Creation of Smart Fertilizers

This research presents the mechanical creation of smart fertilizers from a mixture of smectite and urea in a 3:2 ratio by using the planetary milling technique. The smectite–urea composites show intercalation between urea and mineral, which increases steadily with increasing activation time. A shift of X-Ray Diffraction basal reflections, intensities of Fourier transform infrared spectroscopy (FTIR) peaks, and weight losses in thermogravimetric analysis (TG) document the systematic crystallo-chemical changes of the composites related to nitrogen interaction with activation. Observations of the nanocomposites by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) corroborate the inference. Nitrogen intercalates with smectite in the interlayer space and remains absorbed either within micro-aggregates or on the surface of activated smectites. Soil leaching tests reveal a slower rate of nitrogen than that of traditional urea fertilizers. Different forms of nitrogen within the composites cause their differential release rates to the soil. The formulated nanocomposite fertilizer enhances the quality and quantity of oat yield.

Neuromuscular Impairment of Knee Stabilizer Muscles in a COVID-19 Cluster of Female Volleyball Players: Which Role for Rehabilitation in the Post-COVID-19 Return-to-Play?

COVID-19 athletes reported persistent and residual symptoms many weeks after initial infection, including cough, fatigue, and neuromuscular disorders. Poor neuromuscular control may cause inefficient movement strategies increasing anterior cruciate ligament load. This is particularly relevant in female athletes, who show a 3-time higher risk than male counterparts. Aim is to evaluate the impairment in thigh muscles activation, body composition, and physical performance after COVID-19 in volleyball athletes. We recruited a cohort of female professional players from the same team. We assessed the pre-activation time of Rectus Femoris (RF), Vastus Medialis (VM), Medial Hamstring (MH), and Lateral Hamstring (LH) before (T0) and after (T1) COVID-19 infection, bioelectrical impedance analysis (BIA), and jump tests. We included 12 athletes with COVID-19 infection diagnosis in January 2021. At T1 we found a significant (p < 0.05) delay (ms) of the activation time of RF (426 ± 188 vs. 152 ± 106); VM (363 ± 192 vs. 140 ± 96); BF (229 ± 60 vs. 150 ± 63); MH (231 ± 88 vs. 203 ± 89), and a significant reduction of body composition at BIA. The neuromotor imbalance of the knee stabilizer muscle in female athletes after COVID-19 infection determines a deficit of knee stabilization. Physicians should consider neuromuscular and metabolic sequelae to identify athletes at higher risk of injury and set up specific neuromuscular rehabilitation protocols.

Influence of freezing temperature on semen quality of rainbow trout (Oncorhynchus mykiss)

Trout production in Peru has export potential. However, there are no fry available to maintain production throughout the year and there is also a lack of egg production at certain times of the year. Therefore, the alternative is to cryopreserve semen for the non-reproductive season. The objective of the study was to determine the influence of freezing temperature on the quality of rainbow trout semen. The semen of 12 reproductive males was collected in the facilities of the Chucuito Research and Production Center of the National University of the Altiplano of Puno, which underwent a macroscopic, microscopic pre and post thaw seminal evaluation and the fertility rate was measured. Due to the effect of three freezing temperatures (-80 °C, -100 °C, -120 °C), cryopreservation had a decline curve of -20 °C / min. The fresh seminal parameters were similar to those reported by other researchers. While freezing had unfavorable effects on semen quality, the best results for activation time (51.33 sec) and vitality (35.33%) were obtained with -100 °C, but the higher motility was obtained with -120 °C (36.33%). Regarding fertility, the higher rate was obtained with -100 °C (70.97%), followed by -80 °C and -120 °C in which 68.86% and 64.34% were obtained, respectively. In conclusion, the results suggest that the tolerable freezing temperature of rainbow trout semen is around -100 °C, which is shown as a favorable alternative for the reproductive management of rainbow trout under natural hypobaric conditions of the Peruvian highlands

Features of the morphology and texture of silica and carbon adsorbents

The morphological and textural characteristics of various silicas (93 fumed silicas and 56 porous silicas), different carbons (230), and porous polymers (53) are analyzed using probe (nitrogen, argon, benzene, n-decane, water) adsorption, small angle X-ray scattering (SAXS), and transition (TEM), scanning (SEM) electron and atom force (AFM) microscopies. There are certain correlations between pore volume (Vp) and specific surface area (SSA, SBET) for these materials. Synthesis and treatment temperatures affect this relationship since a linear Vp - SBET approximation scatter decreases with decreasing these temperatures. Silicas are composed of nonporous nanoparticles (NPNP), but activated carbons (AC) are composed of porous nanoparticles (PNP). For different materials, NP are weakly or strongly packed in secondary structures. However, there are general features of pore size distributions (PSD) for NP-based materials, e.g., minimal contribution of narrow mesopores of 3-5 nm in radius due NP-packing effects. For AC produced using the same chars and activation agents but with varied activation time, the textural characteristics demonstrate smooth changes with increasing burn-off degree: nanopores partially transform into narrow mesopores with opposite PSD shifts of broad mesopores and macropores. Comparison of adsorption (open pores accessible for probes) and SAXS (both open and closed pores) data for carbons shows that the difference decreases with increasing burn-off degree due to decreasing contribution of closed pores. Most clear pictures on the particulate morphology and texture could be obtained in parallel analysis using adsorption, SAXS, and microscopic methods with appropriate data treatments.

A Divergence-Based Approach for the Identification of Atrial Fibrillation Focal Drivers From Multipolar Mapping: A Computational Study

The expanding role of catheter ablation of atrial fibrillation (AF) has stimulated the development of novel mapping strategies to guide the procedure. We introduce a novel approach to characterize wave propagation and identify AF focal drivers from multipolar mapping data. The method reconstructs continuous activation patterns in the mapping area by a radial basis function (RBF) interpolation of multisite activation time series. Velocity vector fields are analytically determined, and the vector field divergence is used as a marker of focal drivers. The method was validated in a tissue patch cellular automaton model and in an anatomically realistic left atrial (LA) model with Courtemanche–Ramirez–Nattel ionic dynamics. Divergence analysis was effective in identifying focal drivers in a complex simulated AF pattern. Localization was reliable even with consistent reduction (47%) in the number of mapping points and in the presence of activation time misdetections (noise &lt;10% of the cycle length). Proof-of-concept application of the method to human AF mapping data showed that divergence analysis consistently detected focal activation in the pulmonary veins and LA appendage area. These results suggest the potential of divergence analysis in combination with multipolar mapping to identify AF critical sites. Further studies on large clinical datasets may help to assess the clinical feasibility and benefit of divergence analysis for the optimization of ablation treatment.

Sorption and Textural Properties of Activated Carbon Derived from Charred Beech Wood

The aim of this study was to prepare activated carbon materials with different porous structures. For this purpose, the biomass precursor, beech wood, was carbonized in an inert atmosphere, and the obtained charcoal was physically activated using carbon dioxide at 1273 K. Different porous structures were obtained by controlling the time of the activation process. Prepared materials were characterized in terms of textural (N2 sorption at 77 K), structural (XRD), and sorption properties (CO2, C2H4, C4H10). The shortest activation time resulted in a mostly microporous structure, which provided a high sorption of CO2. Increasing the activation time led to an increasing of the pores’ diameters. Therefore, the highest ethene uptake was obtained for the material with an intermediate activation time, while the highest butane uptake was obtained for the material with the highest activation time.

Pembuatan Karbon Aktif dari Limbah Plastik PET (Polyethylene terephthalate) Menggunakan Aktivator KOH

Pengunaan plastik setiap hari mengakibatkan terjadinya penumpukan sampah plastik yang dapat mencemari lingkungan dan menjadi salah satu masalah serius yang harus ditangani karena plastik tidak dapat terdegradasi. Plastik merupakan senyawa yang unsur penyusun utamanya adalah karbon dan hidrogen. Sehingga limbah plastik berpotensi sebagai pembuatan karbon aktif dan akan membuat limbah plastik menjadi lebih bermanfaat. Penelitian ini bertujuan untuk mengetahui pengaruh konsentrasi aktivator dan waktu aktivasi terhadap proses aktivasi fisika kimia sehingga menghasilkan produk karbon aktif yang sesuai dengan SNI 06-3730-1995. Plastik PET terlebih dahulu dikarbonasi pada temperatur 480oC selama 2 jam menggunakan furnace hingga membentuk arang. Lalu, direndam dalam aseton selama 24 jam. Setelah itu disaring dan dikeringkan menggunakan oven pada temperatur 110oC selama 3 jam dan dilanjutkan dengan proses aktivasi fisika pada temperatur 750oC selama 2 jam. Karbon yang telah teraktivasi fisika selanjutnya diaktivasi secara kimia dengan menggunakan KOH konsentrasi 1 M, 2 M, 3 M, dan 4M dengan variasi waktu 2 jam dan 4 jam. Diperoleh hasil terbaik yaitu pada karbon aktif dengan konsentrasi KOH 4 M dan waktu aktivasi 2 jam dengan nilai daya serap iod sebesar 980,17 mg/g, kadar abu 0,28%, kadar air 7,55%, dan kadar volatile matter 3,47%. Karbon aktif yang diperoleh telah memenuhi SNI 06-3730-1995.The use of plastic every day results in the accumulation of plastic waste that can pollute the environment and was a serious problem that must be addressed because plastic cannot be degraded. Plastic was a compound whose main constituent elements were carbon and hydrogen. So that plastic waste has the potential to produce activated carbon and will make plastic waste more useful. This study aims to determine the effect of activator concentration and activation time on the physical-chemical activation process so as to produce activated carbon products in accordance with SNI 06-3730-1995. PET plastik was first carbonated at a temperature of 480oC for 2 hours using a furnace to form charcoal. Then, soaked in acetone for 24 hours. After that it was filtered and dried using an oven at a temperature of 110oC for 3 hours and continued with the physical activation process at a temperature of 750oC for 2 hours. The physically activated carbon was then chemically activated using KOH concentrations of 1 M, 2 M, 3 M, and 4 M with time variations of 2 hours and 4 hours. The best results were obtained on activated carbon with a concentration of KOH 4 M and an activation time of 2 hours with an iodine absorption value of 980.17 mg/g, 0.28% ash content, 7.55% water content, and volatile matter levels 3,47%. Activated carbon obtained has complied with SNI 06-3730-1995.

Preparation of fly ash-based flocculant and flocculation performance

Using fly ash from a thermal power plant in Yingkou City as raw material, The inorganic polymer flocculant polyaluminum ferric chloride (PAFC) was prepared by sodium carbonate impregnation, high temperature roasting activation, and acid leaching. The influence of activation temperature and activation time on the leaching of aluminum and iron was investigated through single factor test and orthogonal test. The PAFC preparation conditions were optimized, and the prepared PAFC flocculant product was applied to kaolin turbidity water. The test results showed that the content of aluminum in fly ash was 7.08%, and the content of iron was 4.95%. The mass ratio of the activator sodium carbonate and fly ash was 10:7, the activation temperature was 800°C, and the activation time was 2h. The leaching rates of aluminum and iron were the highest, 88.31% and 53.66% respectively. The optimal conditions for the preparation of the flocculant were as follows: the molar ratio of aluminum to iron was 5.7:1, and the reaction time was 1.5h. The liquid product obtained under these conditions was yellowish brown, and the solid product obtained after being dried was yellow powder.

Perubahan lebar interkaninus rahang atas dengan penggunaan sekrup ekspansi pada jarak waktu aktivasi yang berbedaChanges in the maxillary intercanine width during the use of expansion screws at different activation intervals

ABSTRAKPendahuluan: Penggunaan sekrup ekspansi pada ortodonti lepasan dilakukan untuk melebarkan lengkung gigi. Lebar lengkung gigi dapat diukur salah satunya dengan cara menghitung lebar interkaninus. Tujuan dari penelitian ini adalah untuk mengetahui evaluasi penggunaan sekrup ekspansi terhadap perubahan lebar interkaninus rahang atas berdasarkan kelompok waktu aktivasi. Metode: Metode penelitian yang digunakan adalah analitik. Teknik pengambilan sampel menggunakan purposive sampling. Hasil:. Berdasarkan hasil perhitungan analitik nilai t stat memiliki nilai yang lebih kecil dari nilai t Critical two-tail, maka didapatkan hasil yang menunjukan bahwa terdapat perbedaan yang bermakna dari perubahan lebar interkaninus pada dua kelompok waktu tersebut. Simpulan: Terdapat perubahan lebar interkaninus yang signifikan pada kedua kelompok waktu aktivasi.Kata kunci: sekrup ekspansi, ortodonti lepasan, lebar interkaninus, rahang atasABSTRACTIntroduction: The use of expansion screws in removable orthodontics is used to widen the dental arch. The dental arch width can be measured one of them by calculating the intercanine width. The aim of this study was to evaluation the use of expansion screws for changes in maxillary intercanine width based on activation time groups. Method: This research used analytic method. The sampling technique used purposive sampling. Results: Based on the results of analytical calculations, the value of t stat has a value smaller than t Critical two-tail, the results obtained indicate that there are significant differences in changes in intercanine width in the two time groups. Conclusion: There was a significant change in intercanine width in both groups of activation time. Keywords: expansion screws, removable orthodontics, intercanine width, maxillary