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Cu nanoparticles supported on ZrO2 (CuNPs@ZrO2) were synthesized using a one‐step co-precipitation process, and their application in C–C coupling reactions was investigated. The catalyst was characterized using XRD, XPS, SEM, TEM, and TGA techniques. The prepared catalyst was used for the Sonogashira cross-coupling reactions of aryl bromides with phenyl-acetylene in the presence of K2CO3 in DMF at 110 °C, which resulted in substituted alkynes with good to excellent yields. The protocol was also extended for the Ullmann coupling reactions of aryl iodides under similar reaction conditions, yielding the desired products with good to excellent yields without homo-coupling. Interestingly, unlike other copper catalysts, the present catalyst worked under air and did not require an inert atmosphere to prevent alkyne. This catalytic system is versatile, tolerant, and significantly cheaper than the "traditional" Pd-catalyzed Sonogashira cross-coupling of terminal alkynes with aryl halides. The catalyst could be reused for five catalytic cycles with no significant change in the product yield. All of these characteristics make our prepared CuNPs@ZrO2 catalyst quite suitable for the gram-scale synthesis of biaryls and alkynes, with a simple workup. [ABSTRACT FROM AUTHOR]

Polyfuranic compounds produced after carbon up-gradation of 2-methylfuran by acid catalyzed C–C bond forming reactions when undergo hydro-deoxygenation produce diesel fuel. Herein, we prepared a simple and novel silica supported sulfonic acid functionalized isonicotinic acid SO3H-INA@SiO2 catalyst by treating isonicotinic acid with chlorosulphonic acid followed by heterogenization on silica. This heterogeneous solid acid catalyst was explored for the solvent free conversion of 2-methylfuran to diesel fuel precursors of C15 and C20 units via tandem ring opening followed by condensation sequence. Under optimized reaction conditions, SO3H-INA@SiO2 was able to convert, 2-methylfuran completely into condensation products such as 5,5-bis(5-methylfuran-2-yl)pentan-2-one (1) and 2,4,4-tris(5-methylfuran-2-yl)pentan-1-ol (2) with 19% and 67% yields, respectively. The heterogeneous SO3H-INA@SiO2 catalyst was successfully recycled up to six consecutive runs without loss of its activity. The SO3H-INA@SiO2 catalyst offered superior activity as compared to the commercially available -SO3H functionalized resins. Superior activity of the prepared catalyst could be attributed for its higher acidity, smaller particle size and high surface area. Structure of the prepared catalyst was confirmed by FTIR and solid state NMR. Total acidity of the prepared catalyst was determined by acid–base titration. [ABSTRACT FROM AUTHOR]

Purpose Effectual waste utilization from plant as well as marine biomass has gained tremendous importance with reference to sustainability. The valorization of marine biomass produces value added compounds containing not only C, H, O but also renewable N atom in the skeleton which widens the scope for its exploration which may prove to be economically beneficial to the society. Heterogeneous catalytic transformation of marine biomass i.e. N-acetyl glucosamine (NAG) to N-substituted aromatic heterocyclic furan derivatives is reported for the very first time. Cost effective and stable metal oxide catalysts were deployed for the transformation. Catalyst screening study showed that La2O3 was found to be an excellent catalyst for N-acetyl glucosamine (NAG) dehydration which mainly produced 3-acetamidofuran (3AF). Methods The physicochemical properties of the metal oxide catalyst were investigated by various techniques such as XRD, FTIR, MeOH-FTIR, TPD, SEM, N2 sorption studies and HR-TEM analysis for structure activity relationship. Results The effect of various reaction parameters such as catalyst concentration, reaction temperature, reaction time and solvent effect on dehydration of N-acetyl glucosamine has been studied in detail for higher yields. The results revealed that the presence of weak basic sites which are Brønsted in nature and nano pores present on the surface were responsible for improved dehydration of the chitin biomass to selectively yield 3-acetamidofuran (3AF). La2O3 catalyst showed optimum 50% 3AF yield from N-acetyl glucosamine at 180 °C in 3 h. Conclusion Efficacious exploitation of marine biomass to value added chemicals using heterogeneous catalysts can be extensively exploited. Separation of N-substituted heterocyclic aromatics is the most innovative aspect of the current study. Thus, utilization of heterogeneous catalyst and renewable biomass as a raw material indicates a transition towards more sustainable and greener approach. With reference to valorization of biomass waste towards sustainability. We report for the first time heterogeneous catalytic transformation of marine biomass i.e. N-acetyl glucosamine (NAG) over La2O3 catalyst to yield 50% 3-acetamido furan (3AF) and 20% 3-acetamido-5-acetylfuran with 100% NAG conversion. The superior performance of La2O3 catalyst was attributed to the presence of brønsted basicity and nanopores present at catalysts surface. [ABSTRACT FROM AUTHOR]

We investigated the effect of femtosecond (fs) laser ablation of enamel and dentin for different pulse wavelengths: infrared (1030 nm), green (515 nm), and ultra-violet (343 nm) and for different pulse separations to determine the optimal irradiation conditions for the precise removal of dental hard tissues with the absence of structural and compositional damage. The ablation rates and efficiencies were established for all three laser wavelengths for both enamel and dentin at room temperature without using any irrigation or cooling system, and the surfaces were assessed with optical and scanning electron microscopy, optical profilometry, and Raman spectroscopy. We demonstrated that 515 nm fs irradiation provides the highest rate and efficiency for ablation, followed by infrared. Finally, we explored the temperature variations inside the dental pulp during the laser procedures for all three wavelengths and showed that the maximum increase at the optimum conditions for both infrared and green irradiations was 5.5 °C, within the acceptable limit of temperature increase during conventional dental treatments. Ultra-violet irradiation significantly increased the internal temperature of the teeth, well above the acceptable limit, and caused severe damage to tooth structures. Thus, ultra-violet is not a compatible laser wavelength for femtosecond teeth ablation. [ABSTRACT FROM AUTHOR]

Commercial biodiesel production is becoming popular due to its sustainability and reduced greenhouse gas emissions in comparison to fossil fuels. Biodiesel production involves the co-generation of crude glycerol that is not directly viable. Valorization of glycerol is essential from techno-economic perspective to achieve goals of circular economy. In this study, the glycerol etherification was carried out using tert-butyl alcohol in presence of dodecatungstophosphoric/silica (DTP/SiO2) catalyst for production of tert-butyl glycerol ethers that can be used as fuel additives. A series of DTP/SiO2 catalysts were prepared with various compositions by impregnating heteropoly acids (HPA, H3PW12O40). The product analysis was performed to monitor mono-, di-, and tri-tert-butyl glycerol ethers. The kinetic studies were conducted based on Langmuir–Hinshelwood model. The rate constants were determined from experimental data by regression analysis. The catalysts were characterized by X-ray diffraction, SEM/EDX, and thermogravimetric analysis. Varying DTP loadings resulted in different catalytic activities. Activation energy (38.23 kJ/mol), activation enthalpy (25.94 kJ/mol), activation entropy (− 163.8 J/mol/K), and Gibbs free energy of activation (88.67 kJ/mol) were attained for DTP/SiO2 (20%) catalyst that exhibited the best selectivity for di-tert-butyl glycerol ethers. [ABSTRACT FROM AUTHOR]

The infrared transmission and reflection spectra of a series of samples of bismuth films of different thicknesses on identical single-crystal silicon substrates were measured. Transmission and reflection oscillations caused by interference on the film thickness are investigated. Properties of Si-plates are estimated. Refractive index and absorption index of bismuth are calculated. [ABSTRACT FROM AUTHOR]

In the present work, we invented a Pd nanoparticle immobilized on an amine-functionalized LDH catalyst (PdNP@NH2-LDH-Al-MCM-41) for cross-coupling reactions. The palladium was grafted onto the support by treating the Pd(OAc)2 with NH2-LDH-Al-MCM-41 in acetone at room temperature. The prepared catalyst was characterized by FT-IR, SEM, TGA, TEM, and XPS techniques. The TEM characterization of the catalyst showed the uniform distribution of PdNPs with sizes ranging from 3 to 6 nm located inside the mesoporous. The Suzuki–Miyaura cross-coupling reaction was used to demonstrate the catalytic efficiency of the prepared PdNPs@NH2-LDH-Al-MCM-41 catalyst. The prepared and analyzed catalyst showed good to excellent activity in the Suzuki–Miyaura cross-coupling reaction of various aryl bromides with different aryl boronic acids in ethanol at 80 °C. The catalyst showed TON up to ~ 47 and TOF ~ 47 h−1. The catalytic results exhibited that the catalyst is completely recoverable with simple filtration. The catalytic efficiency shows a slight decrease in activity for the Suzuki–Miyaura cross-coupling reactions even after five repeated recycles. TEM images of the freshly prepared and reused catalysts (after five catalytic cycles) showed palladium nanoparticles remain unchanged at the end of the reactions. [ABSTRACT FROM AUTHOR]

There has been a lot of interest in utilizing remote sensing images to anticipate landslides. We propose a novel framework for automatic landslide detection and landslide region localization from the input remote sensing image. The framework consists of pre-processing, dynamic segmentation, automatic feature extraction, classification, and localization. The pre-processing is the integrated step that performs atmospheric corrections, geometric corrections, and unnecessary region removal with denoising using 2D median filtering. The pre-processed image is then segmented using the dynamic segmentation approach to extract the Region of Interest (ROI). We propose lightweight Convolutional Neural Network (CNN) layers for automatic feature extraction and scaling using the ResNet50 model. The CNN layers are designed systematically for automatic feature extraction to improve accuracy and reduce computational requirements. The Long-Term Short Memory (LSTM), Artificial Neural Network (ANN), and Support Vector Machine (SVM) classifiers are designed to perform the landslide prediction. If landslides are forecast, the post-processing stages are intended to identify potential landslide locations. The experimental results show that the proposed CNN-LSTM model outperformed the existing solutions in terms of accuracy, F1 score, precision, and recall rates. The experimental outcomes reveal that the proposed model improves the overall prediction accuracy by 2% and reduces the computational complexity by 35% compared to state-of-the-art methods. [ABSTRACT FROM AUTHOR]

Solvolysis of benzyl phenyl ether (BPE), which is a model compound of lignin ether linkage, was studied in an aqueous ethanol solution, which can be obtained from bioethanol, under high-pressure carbon dioxide conditions. A batch study revealed that BPE solvolysis to monoaromatics (benzyl ethyl ether (BEE), benzyl alcohol (BA), and phenol (Ph)) proceeded in aqueous ethanol solution over 523 K and the addition of high-pressure carbon dioxide enhanced the initial solvolysis rate and suppressed the side reaction (hydrogenolysis to toluene (TL)). The ethanol molar fraction (ethanol–water volume ratio) is the key factor for the solvolysis reaction, and the highest monoaromatic yield of 72.9% (BEE 10.7%, BA 19.3%, Ph 37.9%, and TL 5.1%) was obtained in aqueous ethanol solution (2 cm3 : 1 cm3 = water:ethanol) at 598 K for 3 h under a pressure of 18 MPa of carbon dioxide. The solvolysis reaction proceeded continuously to produce monoaromatics with a flow system. A monoaromatic yield of 76.7% (BEE 8.6%, BA 19.7%, Ph 39.6%, and TL 8.9%) was obtained, and the formation rates were 2.7 × 10−4 mmol min−1 for BEE, 6.2 × 10−4 mmol min−1 for BA, and 12.4 × 10−4 mmol min−1 for Ph at 598 K under flowing water (26 mmol min−1), ethanol solution (4.1 mmol min−1), carbon dioxide (1.2 mmol min−1), and BPE (15.6 × 10−4 mmol min−1) under a total pressure of 40 MPa. [ABSTRACT FROM AUTHOR]

We explore femtosecond laser cleaning of materials used in the construction of historic monuments, such as stone and steel covered in typical contaminants caused by harsh environments that may be found in urban areas. We address the cleaning of these materials from a conservation perspective, taking as examples the preservation and cleaning of iconic structures such as the steel and the granite of the Sydney Harbour Bridge, Hawkesbury sandstone, a popular building material of a variety of monuments in Sydney (Australia), Makrana marble taken from the Soami Bagh Samadh temple of Agra in India, and also graffiti removal. We demonstrate that femtosecond laser pulses can clean a range of different contaminants such as biofilm, environmental soiling, rust, and spray paints, while preserving the integrity of the underlying substrates. Femtosecond laser cleaning is a fast and effective method and a safer alternative to lasers with longer pulse durations for the preservation of historic monuments. [ABSTRACT FROM AUTHOR]

An efficient and convenient method for synthesis of 7,10,11,12-tetrahydrobenzo[c]acridin-8(9H)-one derivatives using Cu/MCM-41 (20 mg) as heterogeneous catalyst. The advantages have an excellent product yield within a short time and easy work-up procedure, and the products have directly recrystallized from hot methanol with cost-effective catalyst. One-pot three-component reaction from aromatic aldehydes, cyclic 1,3-dicarbonyl compounds, and 1-naphthyl amine has been carried under ethanol as a solvent with reflux condition. Moreover, the catalyst can be recovered conveniently and reused efficiently, and recyclable. [ABSTRACT FROM AUTHOR]

Efficient carbonylation of glycerol using urea with Zn‐Co mixed metal oxide (MMO) catalyst has been achieved. Various methods of catalyst preparation were explored for glycerol carbonate (GC) synthesis. The optimized method of catalyst preparation was found to be co‐precipitation (CP) with a Zn:Co ratio of 70:30, achieving 81% glycerol conversion with 97% GC selectivity. X‐ray diffraction (XRD) studies revealed the formation of ZnO, Co3 O4, and spinel ZnCo2O4 phases. Thermal treatment given to the catalyst allows insertion of Zn cations into Co3O4 lattice forming ZnCo2O4 phase which was also evidenced in X‐ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Herein, for the first time, reaction kinetics was studied to propose the rate equation, based on which a plausible reaction pathway is proposed involving two‐site adsorption of glycerol (basic site) and urea (acidic site), which undergo carbonylation followed by cyclization into GC. A recycle study and hot filtration test have proven the reusability of the catalyst. [ABSTRACT FROM AUTHOR]

The agricultural sector is the backbone of the Indian economy, where precision agriculture is playing a vital role in boosting productivity. The soil chemical parameters play an important role in precision agriculture. Analysis and prediction of micronutrient of the soil chemical parameters are highly insisted upon by farmers and agriculture researchers. The soil nutrients parameters can be analyzed from multispectral data through ISO cluster unsupervised classification. Understanding the nutrient level of soil is highly recommended for farming; early understanding may help to improve soil fertility and fully meet productivity requirements. This paper addresses the soil nutrients analysis by the regression method and its spectral indexed based on the prediction model by Iterative Self-Organizing (ISO) cluster unsupervised classification algorithm. Therefore, for this study, the Baggi, Ibrahimpur, Wai, Mogra, and Bori (for validation) villages were selected. These villages are located in the Amravati district and fall under Maharashtra provenance of India. From the study area, three soil nutrients parameters such as P, Fe, pH indices-based data were acquired from the spectral calculation of Sentinel-2 and Landsat-8 bands. The P, Fe and pH indices were calculated from the yellowness index (YI), ferrous oxide index, and carbonate level. The ISO cluster unsupervised mechanism has been used for prediction of soil chemical parameter indices out of 100 samples. The study regions recognition rate is 97% for P, 94.05% for Fe, and 69% for pH. During the validation process, four villages' results were used for the identification of soil nutrient parameters for Bori village. The results of the study area can be helpful for the development of the planning of soil fertility in the agriculture fields and effectively increase the crop yield production in the semi-arid region. [ABSTRACT FROM AUTHOR]

Hierarchical TS-1 materials were synthesized using hydrothermal synthesis and a post modification technique through desilication. They were evaluated for hydroxylation of anisole to produce industrially important chemicals, o-methoxyphenol (OMP) and p-methoxyphenol (PMP). The detailed characterization of the prepared catalysts, such as morphology, structure, nature of Ti and surface area were obtained by SEM, HR-TEM, XRD, UV-VIS spectroscopy and the BET technique. The effects of various operational parameters such as substrate/H2O2 molar ratio, reaction temperature, catalyst concentration and solvent effect on the hydroxylation of anisole have been studied in detail. The microporous TS-1 catalyst showed 32% anisole conversion with 34% selectivity to PMP, while the micro/mesoporous DTS-1 catalyst showed enhanced activity for anisole hydroxylation, i.e. 54% conversion with 55% selectivity towards PMP. The increased framework Ti and improved accessibility of the active sites located in the channels of DTS-1, which permit the mass transfer of reactants, transition states and products from the mesopores of DTS-1, were responsible for the enhanced catalytic activity and selectivity towards p-methoxyphenol. [ABSTRACT FROM AUTHOR]

Catalytic synergism was observed for a bimetallic Pd−Ir catalyst supported on activated carbon for chemoselective hydrogenation of 5‐hydroxymetahyl furfural (5‐HMF) to 2, 5‐(bishydroxymethyl) furan (BHMF) with complete conversion and 97 % selectivity under very mild reaction conditions. The structural characterization like XRD, N2 sorption, FE‐SEM and TEM suggested formation of fine nanoparticles (1.95–3.08 nm) having very higher surface area, uniform distribution and mesoporous nature of the material. XPS spectra and Pyridine‐IR spectroscopy revealed formation of Pd‐PdO and Ir/IrO2/IrO3 interface on the catalytic surface along with strong Brönsted acidic sites which were responsible for high efficiency of catalyst at 80 °C, 100 psig H2 pressure at 5‐HMF/Catalyst=20 and within 2.5 h of reaction time. A plausible reaction mechanism is also elucidated based on structure activity correlation. [ABSTRACT FROM AUTHOR]

Heterogeneous catalysis has been utilized in number of efficient reactions with higher selectivity of the product, more stable, reusable and easy for separation as compared to homogeneous catalysts. Generally, heterogeneous catalysts are prepared by using mesoporous materials, microporous materials, metal oxides and metal organic framework. The mesoporous materials have small particle size and high surface area as compared to the microporous materials. The adsorbent mesoporous materials have highly efficient for the therapeutic applications in chemistry hence it has best as compared to other heterogeneous materials. Herein, we have reported synthesis of 1,4-dihydropyridines and polyhydroquinolines at solvent free and environmental benign condition in the presence of Zn/MCM-41 catalyst. The present protocol gives excellent yield (89–96%) of the product within short reaction time by easy work up procedure and no need of further purification of product. The catalyst was characterized by XRD diffractometer, SEM, EDAX, TGA-DTA, BET surface area analysis and FT-IR Spectroscopy. The synthesized organic compounds were characterized by FT-IR, 1H NMR, 13C NMR, LC–MS spectrometry. [ABSTRACT FROM AUTHOR]

Synthesis of levulinate esters which are known to be excellent sustainable fuel additives, was achieved by alcoholysis of furfuryl alcohol over strong solid acid catalyst, prepared by copolymerization of p‐toluenesulfonic acid with paraformaldehyde. Our catalyst possessed Brønsted acidity (3 mmol/g) with an excellent stability up to 220 °C. XPS, FT‐IR and Pyridine‐IR along with microanalysis studies confirmed the presence of terminal −SO3H functional groups responsible for Brønsted acidity in the catalyst. The catalyst was found to efficiently catalyze the alcoholysis of furfuryl alcohol to give alkyl levulinates under mild reaction conditions. The complete conversion of furfuryl alcohol with 96 % and 97 % selectivities to ethyl and butyl levulinates could be achieved using ethanol and butanol, respectively. Detailed study on effect of various reaction parameters like catalyst loading, reaction time and reaction temperature on conversion and product distribution was also carried out for the ethanolysis of furfuryl alcohol to ethyl levulinate. The catalyst could be easily recovered and recycled for five times successfully, with no loss in its original activity. [ABSTRACT FROM AUTHOR]

Esterification of glycerol with acetic acid has been studied with different solid acid catalysts, prepared by impregnating phospotungustic, silicotungstic, and phosphomolybdic acids on polymeric material polyvinylpyrrolidone. These results were compared with commercially available montmorillonite KSFO catalyst showed that PVP-DTP gave higher selectivity to di- and triacetins. This study was mainly focused on increasing the selectivity toward triacetin which is an excellent alternative to fossil fuel based fuel additives. The detail characterization was done for the PVP-DTP catalyst which gave complete conversion of glycerol and maximum selectivity of 34% toward triacetin. Complete conversion of glycerol was achieved at 110 °C within 6 h of reaction time. The characterization of the catalyst was performed by SEM/EDX, X-ray diffraction, thermogravimetic techniques, and FT-IR analysis.TPD-NH3 characterization showed that DTP supported on PVP increases the catalyst acidity of PVP. The highest acidity of PVP-DTP is also confirmed using NH3-TPD analysis. [ABSTRACT FROM AUTHOR]

Efficient and highly selective isomerization of glucose to fructose was achieved by using the inexpensive Ba−Zr mixed metal oxide catalyst. Catalyst was prepared by varying Ba−Zr ratios using co‐precipitation method. Various phases formed, planes exposed, morphology, elemental composition and particle size, basic site density and strength, oxidation state of elements were well studied by using various characterization techniques. The XRD analysis clearly indicates the presence of Ba+2 and Zr+4 in the form of BaO, ZrO2 and BaZrO3 phases. The SEM and HR‐TEM images indicate that, Ba−Zr (2 : 1) catalyst prepared showed uniform morphology with spherical and rod‐shaped particles ranging from 300 to 600 nm. Under the optimized reaction conditions Ba−Zr (2 : 1) catalyst exhibited excellent results in terms of 57 % of glucose conversion with 89 % selective formation of glucose. The presence of both acidic as well as basic sites play vital roles in activating the substrate molecules to selectively yield fructose. Ba−Zr (2 : 1) catalyst showed excellent recyclability performance up to four recycles. [ABSTRACT FROM AUTHOR]

A simple and efficient protocol for the ligand-free Mizoroki–Heck coupling reaction of various aryl bromides with different olefins has been reported by using in situ generated PdNPs of size 5–10 nm in aqueous solution of bio-surfactant. The bio-surfactant used in this study is a saponin extract of the seeds of pericarps (pods) of the Acacia concinna plant. The in situ generated PdNPs have been characterized by various techniques such as HRTEM, EDS and XPS. The influence of various parameters such as the nature and amount of bases, the nature of Pd precatalysts as well as the effect of temperature has been investigated on Mizoroki–Heck coupling reaction. The generated PdNPs significantly coupled the various aryl bromides with different olefins in aqueous extract of the seeds of pericarps (pods) of the Acacia concinna plant at 100 °C. [ABSTRACT FROM AUTHOR]

2‐Methyltetrahydrofuran is a valuable commercial product that can be obtained by direct hydrogenation of furfural. In the present study, among several carbon supported bimetallic Ir−Ni catalysts with different loadings screened, 4% Ir‐4% Ni/C catalyst showed excellent activity in terms of direct conversion (99%) to 2‐MeTHF with a maximum selectivity of ∼74% at 220 °C and 750 psig, suppressing the formation of side chain as well as ring opening products. The catalytic activity was found to be mainly affected by catalyst preparation methods, metal loadings, surface composition, temperature, pressure and catalyst loading. HR‐TEM and STEM revealed well dispersed Ir−Ni NPs having the particle sizes in the range of 2 to 5 nm. Different phases of Ir i. e. Ir° and IrO2 as well as oxygen vacancies were found to be responsible for hydrogenation of furfural to 2‐methyl furan while, Ni° and NiO were responsible for further hydrogenation to 2‐MeTHF. The synergic effect between Ir and Ni was established through XPS, H2‐TPR analysis. With the help of some control experiments, the plausible reaction pathway was also proposed. The catalyst prepared by co‐impregnation method found more effective than prepared by sequential addition method. At lower Ni loadings of 1% and 2%, low temperature of 160 °C as well as at low H2 pressure of 250 psig, mixture of furfuryl alcohol and 2‐methyl furan were formed selectively. Catalyst could be successfully reused up to 3 times without leaching of metals. [ABSTRACT FROM AUTHOR]

In this report, we documented novel strategy for the synthesis of bioactive polysubstituted 2-amino-4H-chromine derivatives under a heterogeneous Al-MCM-41-LDH@APTES (ALAM) catalysis. A synthetic procedure is developed to prepare Al-MCM-41-LDH@APTES (ALAM) heterogeneous basic catalysts. Mesoporous Al-MCM-41 is functionalized by known grafting chemistry via layered double hydroxide (LDH) nanosheets and (3-aminopropyl)triethoxysilane (APTES) moiety as a basic organocatalyst. The resulting catalysts contain amino group functionality on the external surface as well as inside the layers and the basicity can be tuned by the loading of APTES. The samples were fully characterized by 29Si and 13C CP/MAS NMR, infrared absorption spectroscopy, TEM, XPS, EDX, TGA, XRD, CO2-TPD, N2 adsorption isotherms measurements, and they were successfully examined for the cascade type Knoevenagel–Michael addition reactions. The product yields associated with these substrates were optimized, and key reaction parameters affecting the yields were identified. The present catalytic method is simple and robust for diversity oriented synthesis which proceeds good to excellent yields without generating any hazards waste. The broad substrate scope, excellent functional group compatibility makes this protocol highly useful towards synthesis of polysubstituted α-cyanoacrylates, α-cyanoacrylonitriles and 2-amino-4H-chromenes with an electron-donating or electron-withdrawing group. We have also successfully established a flow reaction system, gram-scale synthesis as well as catalyst recyclability up to six catalytic cycles without appreciable loss of its activity. [ABSTRACT FROM AUTHOR]

A non-noble bimetallic catalyst Cu–Fe (1 : 2) was magnetically recoverable, highly selective and efficient for 5-(hydroxymethyl) furfural (5-HMF) hydrogenation to 2,5-dimethyl furan (DMF). The structure–activity correlation was established by characterising the prepared catalyst by XRD, XPS, TEM, ESEM, BET surface area, N2-adsorption, NH3-TPD, pyridine-IR and H2-TPR measurements. The high catalytic efficiency was attributed to the oxophilic nature and Lewis acidity of Fe, whereas the selectivity towards DMF was attributed to the Brønsted acidity of CuO and its affinity towards the C–O bond which was further confirmed by NH3-TPD and Py-IR analyses. XPS and XRD revealed the presence of Cu/CuFe2O4 species which catalyzed the hydrogenolysis pathway. TEM and SEM images evidenced the presence of a Cu–Fe nanomorph in which Cu/CuFe2O4 was present. The size of the Cu–Fe nanomorph was found to be between 15.4–17.6 nm. Under the optimised reaction conditions, the highest conversion of 97% and selectivity of 93% were achieved. [ABSTRACT FROM AUTHOR]

Amylase inhibitors, also known as starch blockers, contain substances that prevent dietary starches from being absorbed by the body via inhibiting breakdown of complex sugars to simpler ones. In this sense, these materials are projected as having potential applications in diabetes control. In this context, we report on zinc oxide nanoparticles as possible alpha-amylase inhibitors. Zinc oxide nanoparticles have been synthesized using soft-chemistry approach and 1-thioglycerol was used as a surfactant to yield polycrystalline nanoparticles of size ∼18 nm, stabilized in wurtzite structure. Conjugation study and structural characterization have been done using x-ray diffraction technique, Fourier transform infrared spectroscopy, UV-visible spectroscopy, and transmission electron microscopy. Cytotoxicity studies on human fibrosarcoma (HT-1080) and skin carcinoma (A-431) cell lines as well as mouse primary fibroblast cells demonstrate that up to a dose of 20 μg/ml, ZnO nanoparticles are nontoxic to the cells. We report for the first time the alpha-amylase inhibitory activity of ZnO nanoparticles wherein an optimum dose of 20 μg/ml was sufficient to exhibit 49% glucose inhibition at neutral pH and 35 °C temperature. This inhibitory activity was similar to that obtained with acarbose (a standard alpha-amylase inhibitor), thereby projecting ZnO nanoparticles as novel alpha-amylase inhibitors. [ABSTRACT FROM AUTHOR]

We have measured and analyzed x-ray photoelectron spectra of a series of GexAsySe1-x-y glasses. The valence band spectra show that a number of Se-rich structures exist in the samples. After decomposing Ge, As, and Se 3d spectra into several doublets and assigning them to the different local bond structures, it was found that, while GeSe4/2 tetrahedral, AsSe3/2 pyramidal, and Se trimers decrease in their integrated areas, most defect bonds increase with increasing mean coordination number. Moreover, while the appearance of Se trimers is reasonable in Se-rich samples, they never vanish, even in Se-poor samples. A possible mechanism to form Se trimers in Se-poor samples is discussed. [ABSTRACT FROM AUTHOR]

We have measured and analyzed x-ray photoelectron spectra (XPS) of as-grown and annealed Ge33As12Se55 films compared with bulk material. We found that the as-grown film contains a large number of separated Se clusters which can coalesce with As and Ge after annealing at high temperatures. In addition, both the Ge and As 3d spectra show the presence of oxides. While the Ge oxidation increases with an increasing annealing temperature, As oxidation is almost unaffected by annealing. The difference could be due to their different electro-negativities. Our results suggest that, while thermal annealing is effective to move the film toward the bond structure of bulk glass, the simultaneous surface oxidation must be suppressed in order to achieve high quality films. [ABSTRACT FROM AUTHOR]

Amorphous arsenic sulphide (As2S3) films prepared by ultrafast pulsed laser deposition have been vacuum annealed at a range of different temperatures. Measurements of the glass transition temperature indicate that a crystallization process initiates at annealing temperatures around 170 °C. In combination with Raman scattering analysis, we conclude that phase separation is intrinsic for our as-deposited films. During annealing two sorts of phase transformation are identified: one between different amorphous polymorphs, and another from the amorphous to a crystalline state. We point out a correlation between these two types of transformation and two characteristic time scales identified from measurements of the relaxation of the refractive index, and explain the Arrhenius and non-Arrhenius behaviors leading to the observed temporal characteristics. [ABSTRACT FROM AUTHOR]

Laser ablation of dental enamel with subpicosecond laser pulses has been studied over the intensity range of (0.1-1.4) × 10[sup 14] W/cm² using 95 and 150 fs pulses at a pulse repetition rate of 1 kHz. The experimentally determined ablation threshold of 2.2+0.1 J/cm² was in good agreement with theoretical predictions based on an electrostatic ablation model. The ablation rate increased linearly with the laser fluence for up to 15 times the ablation threshold. The absence of collateral damage was observed using optical and scanning electron microscopy. Pulpal temperature measurements showed an increase of about 10°C during the 200 s course of ablation. However, air cooling at a rate of 5 1/min resulted in the intrapulpal temperature being maintained below the pulpal damage threshhold of 5.5°C. The material removal rates for subpicosecond precision laser ablation of dental enamel are compared with other techniques. [ABSTRACT FROM AUTHOR]

Efficacious waste utilization is vital in context of sustainability. The past decade has witnessed attempts of usage of land biomass and wastes for various applications, contributing towards a sustainable society. Exploitation of the marine biomass, which does not compete with habitation and food production like land biomass has been largely unnoticed and therefore not being utilized judiciously. Researchers have mainly exploited these resources as functional materials having significant potential applications. However, a catalytic perspective for the valorisation of these polymers arising from oceanic waste widens their scope and ameliorates its use. The objective of the present review is to demonstrate the effectiveness of chitin/chitosan as a catalyst and as a feedstock for deriving important fuels and chemicals. It displays all the reactions heterogeneously catalyzed by them along with the strategic methodology. Their important catalytic organic transformations attempted so far, have also been discussed. The future perspectives are also presented which if inculcated would improve the value addition of the waste, paving a way for greener and imperishable world. [ABSTRACT FROM AUTHOR]

The combination of supported rhodium metal catalysts and supercritical carbon dioxide solvent was effective for the stereoselective ring hydrogenations of aromatic compounds at low temperature. Higher solubility of hydrogen in supercritical carbon dioxide provides higher concentration of hydrogen on the rhodium surface, but lower that of the intermediate on rhodium surface, which suppresses the flipping of surface intermediate, leading to higher catalyst activities and cis selectivities to the corresponding ring‐hydrogenated products as compared with those in organic solvents. [ABSTRACT FROM AUTHOR]

Bentonite clay supported cuprous iodide nanoparticles (BENT‐CuI NPs) were prepared and demonstrated for the first time as an efficient heterogeneous catalyst in diversity oriented, green synthesis of 1,2,3‐triazoles by one‐pot, three component reaction between alkyl halides, arylboronic acids, or epoxides with alkynes and sodium azide in aqueous medium. The catalyst was characterized by Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP‐AES), Energy Dispersive X‐ray Spectroscopy(EDS), Scanning Electron Microscopy (SEM), X‐Ray Powder Diffraction (XRD), Transmission Electron Microscopy (TEM) as well as Brunauer‐Emmett‐Teller (BET) techniques and was found to be reusable for five consecutive runs without significant loss of activity. [ABSTRACT FROM AUTHOR]

Etherification of furanic compounds such as furfuryl alcohol (FA) and 5‐(Hydroxymethyl) furfural (5‐HMF) to the corresponding ethers was successfully achieved over Zr‐SBA‐15 catalyst. For this purpose, various Zr‐SBA‐15 catalysts with different Zr/Si molar ratios in self‐generated acidic environment were prepared by one‐pot strategy in self‐generated acidic environment. XRD analysis revealed the increase in the d‐spacing from 9.021 nm for parent SBA‐15 to 11.66 nm for Zr‐SBA‐15, confirming the incorporation of Zr into the framework without disturbing the mesoporous structure of SBA‐15. For the lowest Zr concentration of 0.09 M, hexagonally ordered porous structure was found to be retained as confirmed by TEM while, increase in Zr/Si molar ratio to 0.14, resulted in loss of long range order mesoporosity. The presence of both Lewis and Brønsted acid sites in Zr‐SBA‐15 catalyst as evidenced by py‐IR, were due to the introduction of Zr in the frame work of SBA‐15. The co‐existence of Lewis and Brønsted acid sites in Zr‐SBA‐15 was responsible to catalyze etherification of FA and esterification of levulinic acid producing 2‐(Ethoxymethyl) furan and ethyl levulinate selectively, both of which are bio‐derived fuel additives. Dual‐sites For Fuel (DFF) The adjacent Lewis and Brønsted acid sites introduced due to Zr incorporation into the mesoporous SBA‐15 catalyzed the etherification of furfuryl alcohol with 92% selectivity to 2‐(Ethoxymethyl) furan (2‐EMF). This catalyst was successfully explored for C1‐C4 alcohols for etherification of furfuryl alcohol (FA), 5‐(hydroxymethyl) furfural (5‐HMF) and levulinic acid (LA). [ABSTRACT FROM AUTHOR]

It was demonstrated during the past decade that an ultra-short intense laser pulse tightly-focused deep inside a transparent dielectric generates an energy density in excess of several MJ/cm3. Such an energy concentration with extremely high heating and fast quenching rates leads to unusual solid-plasma-solid transformation paths, overcoming kinetic barriers to the formation of previously unknown high-pressure material phases, which are preserved in the surrounding pristine crystal. These results were obtained with a pulse of a Gaussian shape in space and in time. Recently, it has been shown that the Bessel-shaped pulse could transform a much larger amount of material and allegedly create even higher energy density than what was achieved with the Gaussian beam (GB) pulses. Here, we present a succinct review of previous results and discuss the possible routes for achieving higher energy density employing the Bessel beam (BB) pulses and take advantage of their unique properties. [ABSTRACT FROM AUTHOR]

A uniform size and structure of a composite material are critical assets that determine the properties, such as charge transfer, thermal, photoluminescence, mechanical, etc., and consequently the applications of the material; herein, we report the concept of flame/combustion at a liquid–liquid interface for the first time to synthesize in situ a thin film of a composite consisting of two or more quantum dots. The synthesis of the thin films of a composite containing C and SnO2 QDs having particle sizes below 2 nm was successfully carried out. As compared to single quantum dot systems, the formed composite showed significantly improved specific capacitance due to the synergistic effect arising from the strong interaction between C and SnO2 QDs. This was confirmed by XPS, and UV visible spectroscopy. Moreover, it was confirmed that even after 1000 charge/discharge cycles, the interaction between C and Sn remained unaltered; this indicated significant stability of the capacitance. Some of the advantages of this method include a one-step eco-friendly process and use of ambient conditions. The generality of the method was established by synthesizing C–ZnO and C–TiO2 composite thin films. This new approach can be extended to form many other valuable composite thin films for various applications. [ABSTRACT FROM AUTHOR]

Various iridium supported carbon catalysts were prepared and screened for the direct hydrogenation of furfural (FFR) to 2-methyl furan (2-MF). Amongst these, 5% Ir/C showed excellent results with complete FFR conversion and highest selectivity of 95% to 2-MF at a very low H2 pressure of 100 psig. Metallic (Ir°) and oxide (IrO2) phases of Ir catalyzed the first step hydrogenation involving FFR to FAL and subsequent hydrogenation to 2-MF, respectively. This was confirmed by XPS analysis and some control experiments. At a low temperature of 140 °C, almost equal selectivities of FAL (42%) and 2-MF (43%) were observed, while the higher temperature (220 °C) favored selective hydrodeoxygenation. At optimized temperature, 2-MF was formed selectively while higher pressure and higher catalyst loading favored ring hydrogenation of furfural rather than side chain hydrogenation. With the combination of several control experimental results and detailed catalyst characterization, a plausible reaction pathway has been proposed for the selective formation of 2-MF. The selectivity to various other products in FFR hydrogenation can be manipulated by tailoring the reaction conditions over the same catalyst. [ABSTRACT FROM AUTHOR]

The homogeneous Pd-catalysed Mizoroki–Heck coupling reaction was successfully performed in water in the absence of any additives under aerobic conditions. The various key reaction parameters that affect the yield of the desired cross-coupling product were optimized. The Pd(PPh3)4/Et3N/H2O/98 °C catalyst system was found to be highly active (TOF = 12 to 14 h−1) towards achieving excellent yield of the Mizoroki–Heck coupling products for a wide range of electron-withdrawing as well as electron-donating aryl bromides and chlorides in the shortest reaction time. Pd(PPh3)4 catalyst deactivation during the Mizoroki–Heck coupling reaction was investigated and to evolve a strategy for achieving ten times Pd-metal recyclability without appreciable loss of its activity. Thus, the proposed mechanism provides access to a variety of olefins in aqueous medium, making this protocol eco-friendly. [ABSTRACT FROM AUTHOR]

A new and effective unique two-phase reaction system is investigated for the high yield production of tri(furyl)methane from furfural and furan. This strategy includes the use of an acidic aqueous phase (water + –SO3H functionalized IL) and furan phase, which significantly suppresses polymer formation, thereby increasing the yield of tri(furyl)methane. Furan serves as a reactant as well as an extraction solvent for the recovery of the condensation products. For comparison, different –SO3H functionalized ionic liquids are prepared and their performances evaluated for the condensation of furan and furfural. The ionic liquids with alkyl chain linkers are found to be more effective and acidic than those with imidazolium linked N-sulfonic acids. In addition, an increase in carbon chain length between imidazole/tri-ethylamine/pyridine and –SO3H, increases the catalytic activity of the respective ionic liquids. Among the several prepared ionic liquids, the strongly acidic imidazolium based butylsulfonic acid 6 shows the best activity with a maximum condensation product yield of 84%. This strategy offers a significantly high yield of the condensation products of furan and furfural compared to the traditional mineral acid route. The activity and stability of the –SO3H functionalized 6 is confirmed from seven successful recycles, in which there is no reduction in its activity. Finally, this new strategy is successfully extended for the condensation of furan derivatives (e.g. furan and 2-methylfuran) with several different aldehydes, ketones and alcohols. [ABSTRACT FROM AUTHOR]

Removal of the protecting allyl group from allyl aryl ethers in the presence of other oxygen protecting groups was successfully achieved using a solid acid supported on the high surface area material MCM-41. The catalyst showed excellent activity in the presence of various electron withdrawing, electron donating, and oxidizable functional groups. The methodology is also very useful for the removal of protecting allyl groups of various natural products such as vanillin, isovanillin, and other oxygen functionalized aldehydes and ketones. [ABSTRACT FROM AUTHOR]

In this paper we used digital image processing for germination from X-ray images of cotton seeds. Germination is the process by which a plant grows from a seed. The methods discussed in this paper are internal damages, embryo, and percentage of germination of cotton seeds. The recent development of digital image processing techniques for monitoring cotton seed germination has been done. X-ray analysis can be used to determine the quality of cotton seeds, showing the cause of bad germination. X-ray images provide information on the internal structure and morphology of seeds, mechanical damage, and percentage of empty and filled seeds, micro fractures, possible embryo deformations and insect infestation. This paper various digital image processing techniques which reduces the labour input required to evaluate seedling growth rate and increases the accuracy of these measurements. X-ray photographs were prepared with Faxitron 43805N X-ray Film exposed at 10kev, 2mA (soft X-ray) at a distance of 35cm from the X-ray source for 2min. X-ray photographs were evaluated based on embryo morphology and the presence of endosperm. Embryo morphology was scored as either normal or abnormal. [ABSTRACT FROM AUTHOR]

A new protocol of cascade synthesis for biologically active 2-cyanoacrylamides ( 1) was developed. The reaction proceeds over a novel magnetically retrievable solid-acid composite of iron oxide, poly(vinylpyrrolidone) and phosphotungstic acid (Fe3O4/PVP-PWA) in AcOH-H2O medium under reflux conditions. This transformation is facilitated through single-site Brønsted acid catalyzed cascade reactions involving deacetalization and/or Knoevenagel condensation followed by selective monohydration of nitriles starting from acetals ( 5) and aldehydes ( 2) with malononitrile ( 3). A series of aldehydes, dimethyl and diethyl acetals, along with some heterocyclic aldehydes were successfully transformed to 2-cyanoacrylamides with >95 % yields. TEM images confirmed the coating of the PVP over nanosized Fe3O4. Stereoselective monohydration of 2-benzylidenemalononitriles ( 4) to E isomers was demonstrated by NOESY experiments. The catalyst could be efficiently recycled seven times on employment of both acetals and aldehydes as substrates, as a result of its magnetic nature. [ABSTRACT FROM AUTHOR]

A simple, efficient and ligand-free protocol for the Suzuki–Miyaura reaction and base-free Heck–Matsuda reactions under mild reaction conditions have been developed over palladium supported on activated carbon (Pd/C) in an aqueous hydrotropic solution. The catalyst Pd/C was fully characterized by TG-DTA, SEM, EDS, XRD, XPS, BET and ICP-AES analyses. This green methodology represents a cost-effective and operationally convenient method for the synthesis of a variety of biaryls, prochiral ketones, and acrylates under the conditions that are tolerant for a broad range of functional groups with good to excellent yields. The developed Pd/C–aqueous hydrotrope combined catalytic system is well suited for the 3R approach (reducible, robust, and recyclable) for different cross-coupling reactions without an appreciable loss of its activity. [ABSTRACT FROM AUTHOR]