Preparation and Thickness Optimization of Graphenic-Based Carbon Material as a Microwave Absorber

The purpose of this study is to optimize the thickness of a layered graphenic-based carbon compound, which is a non-magnetic material derived from biomass (old coconut shell). After the sample was exfoliated using HCl solution, the morphological structure showed that the material used in this study is a reduced graphene oxide (rGO), similar to carbon but with a thickness of less than 10 nm and lateral size in submicron (100 nm). The sample with a 2 mm thickness was then characterized using a vector network analyzer (VNA) to measure its reflection loss (RL). The measurement result is evaluated by converting the S-parameter values (S11 and S21) from the VNA using the Nicolsson Ross Weir (NRW) method to obtain input variables such as relative complex permeability and relative complex permittivity. Following this, the single-layer thickness of the sample was optimized using a genetic algorithm (GA), which can predict the appropriate thickness so that the optimum RL can be obtained. The optimum thickness of the sample was found to be 3.48 mm, which resulted in a much higher RL. The RL was re-measured for verification using a sample with the corresponding optimized thickness, revealing that this optimization is feasibly operational for a radar absorbing material (RAM) design. HIGHLIGHTS Carbon compounds containing graphenic phase derived from coconut shell are functional materials having various unique properties such as superior electrical conductivity, large surface area, and excellent structural flexibility, and microwave absorbtion The single-layer microwave absorber employing carbon compounds has been prepared The layer thickness optimized using a genetic algorithm (GA) can estimate the appropriate design with the maximum reflection loss (RL)

Lotus tenuis and Schedonorus arundinaceus co-culture exposed to defoliation and water stress

The present study aimed to investigate the effect of defoliation frequency (low and high) and water stress (excess or deficit) on biomass production, P and N nutrition, and symbiosis with native soil microorganisms on a Lotus tenuis and Schedonorus arundinaceus co-culture in a pot experiment. Combined effects of defoliation frequency and water stress affected plant accumulated shoot biomass. L. tenuis root biomass decreased in response to defoliation and water stress, while S. arundinaceus root biomass was similar between non-defoliated and defoliated plants, at all water levels. Low and high frequencies of defoliation in a waterlogged soil can be considered the most stressful scenario for L. tenuis and S. arundinaceus co-culture. Colonization of arbuscular mycorrhizal fungi in L. tenuis roots and dark septate endophytes colonization in S. arundinaceus roots were affected by both factors, whereas arbuscular mycorrhizal colonization in S. arundinaceus was affected only by water stress. Both plants tolerated defoliation and water stress due to the interaction between the translocation of nutrients and carbon compounds from roots to shoots, and P and N absorption (plus N2 fixation in L. tenuis). Highlights: Both plants tolerated defoliation and water stress due to the interaction between the translocation of nutrients and carbon compounds from roots to shoots, and P and N absorption (plus N2 fixation in tenuis). Low and high frequencies of defoliation in a waterlogged soil can be considered the most stressful scenario for tenuis and S. arundinaceus co-culture. Defoliation frequency increased AM colonization in plant roots under well watered and water deficit conditions. arundinaceus roots were co-colonized by AM fungi and DSE. Promoting the presence of tenuis through low defoliation frequency would improve forage yield and quality with the maintenance of AM symbiosis in legume–grass communities.

Sorbents of Phenols As a Components of the Nutritional Medium in Microclonal Reproduction of Plants

In the process of microclonal reproduction, plants secrete various substances into the nutrient medium, for example, phenolic compounds, which act as inhibitors of growth processes and, accordingly, prevent the normal development of explants in vitro. Plant tissues are treated with stabilizing substances, and various sorbents are also used as components of the nutrient medium to neutralize the negative effects of phenols. This paper presents an overview of the approved methods for solving the problem of sorption of phenolic compounds during microclonal propagation of plants. Various studies are considering the addition of certain components to the nutrient medium that prevent the release of harmful growth-inhibiting substances. Most often, various carbon compounds, such as activated carbon, are used as an adsorbent. The authors, based on the analysis of domestic and foreign literature on this topic, conclude that the most effective and frequently used are carbon compounds and the polymer polyvinyl pyrrolidone, less common is the use of the following inhibitory substances: ascorbic and citric acids, silver nitrate and mercury chloride. According to the results of the conducted analytical studies, the prospects of using such substances as thermally expanded graphite (TEG) and colloidal silicon dioxide as sorbents in the composition of the drug “Polysorb” were revealed. Due to the inhomogeneous porous structure, including both micropores and meso- or macropores, TEG is able to adsorb pollutants both from the solution and from the water surface, which makes it a potential sorbent for phenolic compounds. The effect of silicon dioxide, in amorphous form, on plants in vitro has already been successfully tested by some researchers, which indicates the prospects of its study.

Analisis sumbangan materi hidrokarbon terhadap keterampilan berpikir kritis siswa kelas XI MIA Tahun Ajaran 2018/2019 di SMAN 1 Lawang

In the 21st century, students need to have one of life skill that is critical thinking that can be develop and trained through various aspects and one of which is chemistry aspect. One of the materials in the chemistry aspect is a hydrocarbon material. The purpose of this study was to measure the percentage of hydrocarbon contribution towards student's critical thinking skills and to know the level of critical thinking skills in 11th MIA grade students 2018/2019 academic year at SMAN 1 Lawang. The study used a descriptive quantitative research design. The research subjects which amount to 133 students. Instrument for assessing critical thinking skills used in hydrocarbon material developed by Rodliyah (2018) with critical thinking indicators Ennis (2011). The results of the analysis of the level of critical thinking skills of students using the number of students who scored three on reasoned multiple choice questions and score four on the description questions divided by the total number of sample students, then categorized by percentage according to Karim (2015). The results showed that the hydrocarbon material taught by the teacher was able to bring up the students' critical thinking skills with a level of think critically which was still very low with an average of 1) organic and inorganic carbon compounds by 39.10 percent, 2) identification and source of carbon compounds by 13.53 percent, 3) specificity of carbon atoms by 27.82 percent, 4) nomenclature of hydrocarbon compounds by 16.29 percent, 5 ) isomer hydrocarbon compounds by 9.62 percent, 6) physical and chemical properties of hydrocarbons by 29.32 percent for the subject matter of the physical properties of hydrocarbons, the subject matter of the hydrocarbon compound combustion reaction by 5.71 percent, the subject of substitution reactions alkane compounds by 0.94 percent, the subject matter of the reaction of alkene compounds by 11.58 percent, the subject matter of the reaction of alkaline compounds by 3.57 percent, and the sub-topics of identification were saturated and unsaturated hydrocarbons by 0.75 percent, and 7) the use of hydrocarbons by 14.43 percent. Salah satu kecakapan hidup yang harus dimiliki siswa pada abad 21 adalah keterampilan berpikir kritis yang dapat dikembangkan dan dilatih melalui beragam bidang, salah satunya adalah bidang kimia yaitu pada materi hidrokarbon. Tujuan penelitian ini mengukur persentase sumbangan materi hidrokarbon terhadap kemampuan keterampilan berpikir kritis siswa dan mengetahui tingkat kemampuan keterampilan berpikir kritis siswa kelas XI MIA tahun ajaran 2018/2019 di SMAN 1 Lawang. Penelitian menggunakan rancangan penelitian kuantitatif deskriptif dengan subjek penelitian 133 siswa. Instrumen penilaian keterampilan berpikir kritis yang digunakan pada materi hidrokarbon yang dikembangkan oleh Rodliyah (2018) dengan indikator berpikir kritis Ennis (2011). Data berupa skor 3 pada soal pilihan ganda beralasan dan skor 4 pada soal uraian yang telah diperoleh dianalisis sesuai dengan pengelompokkan pokok bahasan pada materi hidrokarbon lalu dikategorikan berdasarkan jumlah persentase menurut Karim (2015). Hasil penelitian menunjukkan bahwa materi hidrokarbon yang diajarkan oleh guru mampu memunculkan kemampuan keterampilan berpikir kritis siswa dengan tingkat kemampuan keterampilan berpikir kritis yang masih tergolong sangat rendah dengan rata-rata antara lain 1) senyawa karbon organik dan anorganik sebesar 39,10 persen, 2) identifikasi dan sumber senyawa karbon sebesar 13,53 persen, 3) kekhasan atom karbon sebesar 27,82 persen, 4) tata nama senyawa hidrokarbon sebesar 16,29 persen, 5) isomer senyawa hidrokarbon sebesar 9,62 persen, 6) sifat fisika dan kimia senyawa hidrokarbon pada sub pokok bahasan sifat fisika senyawa hidrokarbon sebesar 29,32 persen, sub pokok bahasan reaksi pembakaran senyawa hidrokarbon sebesar 5,71 persen, sub pokok bahasan reaksi substitusi senyawa alkana sebesar 0,94 persen, sub pokok bahasan reaksi senyawa alkena sebesar 11,58 persen, sub pokok bahasan reaksi senyawa alkuna sebesar 3,57 persen, dan sub pokok bahasan identifikasi senyawa hidrokarbon jenuh dan tak jenuh sebesar 0,75 persen, dan 7) kegunaan senyawa hidrokarbon sebesar 14,43 persen.

Biochars in Iron Ores Sintering Process: Effect on Sinter Quality and Emission

The article presents results of the research on the use of chars produced during pyrolysis of residual biomass as a substitutional fuel in the iron ore sintering process. Such an approach allows to implement circular economy and industrial symbiosis to the iron and steel branches. The effect of the substitution of conventional coke breeze fuel used in sintering on final sinter quality and emission was examined. With regard to productivity, fuel consumption, and properties of the sinter it was shown that the share of tested biochars in fuel may be kept at 10, and up to 30, wt.%, depending on the biochar type. It was observed that with the use of the biochars, the content of iron oxide in the sinter decreased, which was advantageous. Moreover, the sinter obtained in the presence of biochars was characterized with better strength and abrasion than the sinter obtained with coke breeze-based fuel, improving the final product quality. The presence of biochar influenced the raw exhaust gas composition and resulted in a slight increase of organic and inorganic carbon compounds content, while the amount of sulfur oxides was noticeably decreased. It was concluded that the biochars may be applied in the sintering process at established share in the fuel stream.

Emerging Cellular-Based Therapies in Carbon Monoxide Poisoning

Carbon monoxide (CO) is an odorless and colorless gas has multiple sources that include engine exhaust, faulty furnaces and other sources of incomplete combustion of carbon compounds such as house fires. The most serious complications for survivors of consequential CO exposure is persistent neurological sequelae occurring in up to 50% of patients. CO inhibits mitochondrial respiration by specifically binding to the heme a3 in the active site of CIV like hydrogen sulfide, cyanide and phosphides. While hyperbaric oxygen remains the cornerstone for treatment, it has variable efficacy requiring new approaches to treatment. There are a paucity of cellular-based therapies in the area of CO poisoning, there have been recent advancements that include antioxidants and a mitochondrial substrate prodrug. The succinate prodrugs derived from chemical modification of succinate are endeavored to enhance delivery of succinate to cells, increasing uptake of succinate into the mitochondria, and providing metabolic support for cells. The therapeutic intervention of succinate prodrugs is thus potentially applicable to patients with CO poisoning via metabolic support for fuel oxidation and possibly improving efficacy of HBO therapy.