The Spectroscopic and Antimicrobial Yield of Sol-Gel Derived Zinc Copper Silicate/E102 Nanoclusters

The structural and optical properties of 30 ZnO: 50 SiO2: (20-x) CuO (ZSC) loaded with E102 (tartrazine dye) (where x=0.02, 0.05, 0.07 wt.%) nanoclusters have been explored. These nanoclusters were synthesized by a sol-gel route followed by a very controlled crystallization process at 500oC. The phase formation, structural modification, and particle distribution behavior of these nanoclusters have been studied using XRD and TEM analysis to monitor the domestic environment for ZCS-E102. The optical transmission and reflection properties of nanoclusters in the UV-Vis-NIR range were studied for the present nanoclusters from which the optical absorption was calculated. Tauc method is employed to estimate the type and value of energy needed to gap transition from absorption data. The direct and indirect gap shows decreased energy need for its transition by E102 concentration increase. The antimicrobial potentials of four synthesized nanoclusters were performed against some pathogenic microbes. The toxicity performance of all studied nanoclusters is measured. Results revealed that ZSC-0.07E102 is showed an effective antimicrobial action against four tested pathogenic microbes in terms of excellent inhibitory effect and biocompatibility show noticeable potential in the antimicrobial application. Therefore, this proficient nanomaterial is a promising choice for biomedical purposes.

Rietveld Refinement and X-ray Absorption Study on the Bonding States of Lanthanum-Based Perovskite-Type Oxides La1-xCexCoO3

Metal-oxygen bonding of the Ce-doped LaCoO3 system remains largely unexplored despite extensive studies on its magnetic properties. Here, we investigate the structure and local structure of nanoscale La1-xCexCoO3, with x = 0, 0.2, and 0.4, using the Rietveld refinement and synchrotron X-ray absorption techniques, complemented by topological analysis of experimental electron density and electron energy distribution. The Rietveld refinement results show that LaCoO3 subject to Ce addition is best interpretable by a model of cubic symmetry in contrast to the pristine LaCoO3, conventionally described by either a monoclinic model or a rhombohedral model. Ce4+/Co2+ are more evidently compatible dopants than Ce3+ for insertion into the main lattice. X-ray absorption data evidence the partially filled La 5d-band of the pristine LaCoO3 in accordance with the presence of La–O bonds with the shared-type atomic interaction. With increasing x, the increased Ce spectroscopic valence and enhanced La–O ionic bonding are noticeable. Characterization of the local structures around Co species also provides evidence to support the findings of the Rietveld refinement analysis.

Retrieval of Phytoplankton Pigment Composition from Their In Vivo Absorption Spectra

Algal pigment composition is an indicator of phytoplankton community structure that can be estimated from optical observations. Assessing the potential capability to retrieve different types of pigments from phytoplankton absorption is critical for further applications. This study investigated the performance of three models and the utility of hyperspectral in vivo phytoplankton absorption spectra for retrieving pigment composition using a large database (n = 1392). Models based on chlorophyll-a (Chl-a model), Gaussian decomposition (Gaussian model), and partial least squares (PLS) regression (PLS model) were compared. Both the Gaussian model and the PLS model were applied to hyperspectral phytoplankton absorption data. Statistical analysis revealed the advantages and limitations of each model. The Chl-a model performed well for chlorophyll-c (Chl-c), diadinoxanthin, fucoxanthin, photosynthetic carotenoids (PSC), and photoprotective carotenoids (PPC), with a median absolute percent difference for cross-validation (MAPDCV) < 58%. The Gaussian model yielded good results for predicting Chl-a, Chl-c, PSC, and PPC (MAPDCV < 43%). The performance of the PLS model was comparable to that of the Chl-a model, and it exhibited improved retrievals of chlorophyll-b, alloxanthin, peridinin, and zeaxanthin. Additional work undertaken with the PLS model revealed the prospects of hyperspectral-resolution data and spectral derivative analyses for retrieving marker pigment concentrations. This study demonstrated the applicability of in situ hyperspectral phytoplankton absorption data for retrieving pigment composition and provided useful insights regarding the development of bio-optical algorithms from hyperspectral and satellite-based ocean-colour observations.

Investigations on Structural and Optical Properties of Various Modifier Oxides (MO = ZnO, CdO, BaO, and PbO) Containing Bismuth Borate Lithium Glasses

Bismuth based quaternary glasses with compositions BiBLM: 50Bi2O3–20B2O3–15Li2O–15MO (where MO = ZnO, CdO, BaO, and PbO) were processed by conventional melt quenching. The effectiveness of various modifier oxides on the optical and structural properties of the developed glasses was studied systematically by XRD, DSC, FTIR, Raman, and optical absorption (OA) measurements. The synthesized glass specimens were characterized by XRD and the patterns demonstrated an amorphous nature. The physical characteristics such as molar mass, density, and OPD values were found to increase with an increase in the molar mass of the modifier oxides, while there was a decrement in oxygen molar volume, thus resulting in decrement of complete molar volume of the prepared glasses. From DSC analysis, incorrigible reduction and enhancement of Tg and thermal stability among various modifier oxides in the glass network was noticed. Optical absorption data for glass specimens have confirmed the decrease in both direct and indirect optical band gap values among various modifier oxides incorporation. These investigations support the obtained Urbach energy (UE) and metallization criteria of synthesized glasses. The ionic characteristic for the glass specimens were confirmed by the values of electronic polarizability and electronegativity. The Raman and FT-IR spectra of the glass specimens displayed the existence of BiO3, BiO6, ZnO4, CdO4, BaO4, BO3, PbO4, and BO4 structural units within the glass matrix. These structural results can support the applications of as-developed glasses in the area of photonics.

PENINGKATKAN HASIL BELAJAR EKONOMI DENGAN METODE DISKUSI TERBIMBING PADA SISWA KELAS XII IPS SMA NEGERI 1 BONE

This research is a classroom action research conducted at SMA Negeri 1 Bone and aims to determine the improvement of students' economic learning outcomes and learning activities using the guided discussion method. The research subjects were students of class XII Social Sciences at SMA Negeri 1 Bone in the 2019/2020 school year, totaling 30 people with varying levels of ability and student absorption. Data retrieval is done by using a test of learning outcomes in the form of an essay. The data collected were analyzed using quantitative and qualitative analysis. In addition, to determine the activeness of students in the learning process with the guided discussion method used observation sheets during teaching and learning activities take place. The results showed that: (a) after being given the action with the guided discussion method there was an increase in the average score of the economic learning outcomes of Class XII Social Sciences students at SMA Negeri 1 Bone which at the end of Cycle I was 72.40 to 78.43 at the end of Cycle II. ; (b) an increase in student learning activity in the learning process from Cycle I to Cycle II; and (c) based on the standard category, the score of economic learning outcomes is categorized as high. From the results above, it can be concluded that the guided discussion method can improve economic learning outcomes for Class XII Social Studies students at SMA Negeri 1 Bone ABSTRAKPenelitian ini adalah penelitian tindakan kelas yang dilaksanakan di SMA Negeri 1 Bone dan bertujuan untuk mengetahui peningkatan hasil belajar ekonomi siswa dan aktivitas belajar dengan menggunakan metode diskusi terbimbing. Penelitian ini menggunakan dua siklus dengan langkah-langkah untuk setiap siklus terdiri dari: perencanaan tindakan, pelaksanaan tindakan, observasi dan evaluasi, serta refleksi. Hal ini dimaksudkan agar manakala peneliti menemukan permasalahan yang perlu perbaikannya, dapat dilaksanakan pada siklus berikutnya. Subjek penelitian adalah siswa kelas XII IPS SMA Negeri 1 Bone pada tahun pelajaran 2019/2020 yang berjumlah 30 orang dengan tingkat kemampuan dan daya serap siswa yang sangat bervariasi. Pengambilan data dilakukan dengan menggunakan tes hasil belajar dalam bentuk essay. Data yang terkumpul dianalisis dengan menggunakan analisis kuantitatif dan kualitatif. Di samping itu, untuk mengetahui keaktifan siswa dalam proses pembelajaran dengan metode diskusi terbimbing digunakan lembar observasi selama kegiatan belajar mengajar berlangsung. Hasil penelitian menunjukkan bahwa: (a) setelah diberikan tindakan dengan metode diskusi terbimbing terjadi peningkatan skor rata-rata hasil hasil belajar ekonomi siswa Kelas XII IPS SMA Negeri 1 Bone yang pada akhir Siklus I sebesar 72,40 menjadi 78,43 pada akhir Siklus II; (b) terjadi peningkatan keaktifan belajar siswa dalam proses pembelajaran dari Siklus I ke Siklus II; dan (c) berdasarkan kategori standar, perolehan skor hasil belajar ekonomi dikategorikan tinggi. Dari hasil di atas dapat disimpulkan bahwa metode diskusi terbimbing dapat meningkatkan hasil belajar ekonomi siswa Kelas XII IPS SMA Negeri 1 Bone

Conversion of Organic Dyes into Pigments: Extraction of Flavonoids from Blackberries (Rubus ulmifolius) and Stabilization

The blackberry’s color is composed mainly of natural dyes called anthocyanins. Their color is red–purple, and they can be used as a natural colorant. Anthocyanins are flavonoids, which are products of plants, and their colors range from orange and red to various shades of blue, purple and green, according to pH. In this study, the chemical composition of an extract obtained from blackberries was defined by LC-ESI/LTQOrbitrap/MS in positive and negative ionization mode. Furthermore, we investigated the adsorption process of blackberry extract using several inorganic fillers, such as metakaolin, silica, Lipari pumice, white pozzolan and alumina. The pigments exhibit different colors as a function of their interactions with the fillers. The analysis of the absorption data allowed the estimation of the maximum adsorbing capacity of each individual filler tested. Through thermogravimetric measurements (TGA), the thermal stability and the real adsorption of the organic extract were determined.

Strong emission at 1000 nm from Pr3+/Yb3+-codoped multicomponent tellurite glass

We have investigated the spectroscopic properties of Pr3+-doped and Pr3+/Yb3+-codoped tellurite glass with the molar composition 78TeO2–10Nb2O5–5PbO–1PbF2–5Li2O–1La2O3. Analysis of the absorption data has allowed us to calculate the radiative lifetimes of 3P0 excited state of Pr3+ ions and 2F5/2 excited state of Yb3+ ions as being equal to 9.43 and 440 µs, respectively. These values appear to be much higher than those obtained from the lifetime measurements indicating the presence of various energy transfer mechanisms. This conclusion is supported by analysis of the emission spectra obtained for doped glasses under the 445 nm excitation; the visible spectra consist of only Pr3+ transitions, while the near infrared spectrum of Pr3+/Yb3+-codoped glass demonstrates a strong emission from the 2F5/2 excited state of Yb3+ ion around 1000 nm. This emission is a result of the Pr3+–Yb3+ down-conversion energy transfer and its efficiency for our Pr3+/Yb3+-codoped glass is estimated as 29%. For potential applications, it is important to increase this efficiency and further studies are desirable, in particular, an optimal choice of Pr3+ and Yb3+ concentrations to minimize non-radiative energy transfers among the ions through cross-relaxation and energy migration processes.

Excited States of Bromopyrimidines Probed by VUV Photoabsorption Spectroscopy and Theoretical Calculations

We report absolute photoabsorption cross sections for gas-phase 2- and 5-bromopyrimidine in the 3.7–10.8 eV energy range, in a joint theoretical and experimental study. The measurements were carried out using high-resolution vacuum ultraviolet synchrotron radiation, with quantum chemical calculations performed through the nuclear ensemble approach in combination with time-dependent density functional theory, along with additional Franck–Condon Herzberg–Teller calculations for the first absorption band (3.7–4.6 eV). The cross sections of both bromopyrimidines are very similar below 7.3 eV, deviating more substantially from each other at higher energies. In the 7.3–9.0 eV range where the maximum cross-section is found, a single and broad band is observed for 5-bromopyrimidine, while more discernible features appear in the case of 2-bromopyrimidine. Several π* ← π transitions account for the most intense bands, while weaker ones are assigned to transitions involving the nitrogen and bromine lone pairs, the antibonding σ*Br orbital, and the lower-lying Rydberg states. A detailed comparison with the available photo-absorption data of bromobenzene is also reported. We have found significant differences regarding the main absorption band, which is more peaked in bromobenzene, becoming broader and shifting to higher energies in both bromopyrimidines. In addition, there is a significant suppression of vibrational structures and of Rydberg states in the pair of isomers, most noticeably for 2-bromopyrimidine.