Chemical Yields Research Articles

Steam explosion of lignocellulosic residues for co-production of value-added chemicals and high-quality pellets

The demand of pellets as energy carrier and the competitiveness of wood biomass are the drivers for finding alternative raw materials for production of pellets. The aim of this study was to investigate the steam explosion of lignocellulosic residues such as, straw, sawdust birch, sawdust spruce, GROT (mixture of 30 % bark and 70 % industrial chips), and their mix to co-production of value-added chemicals and high-quality pellets. The raw materials were first impregnated with water/acetic acid prior to steam explosion process, while leaching and washing of steam exploded biomass was used to reduce the ash content. The value-added chemicals were extracted with MIBK, and a gas chromatography was used to determine which value-added chemicals are present in the MIBK filtrates after extraction of the steam exploded biomass. Thermogravimetric analysis and Fourier transform infrared spectroscopy, elemental analysis, calorific values, compression strength and density were used to assess and compare the quality of steam exploded biomass and pellets quality. The results from the extraction experiments shows that furfural, HMF, vanillin, syringaldehyde and coniferaldehyde are the most value-added chemicals extracted from lignocellulosic residues where higher yield of the valuable chemicals was obtained when the biomass was presoaked in acetic acid. The ash content was reduced by 83 % for straw material by washing and leaching of steam exploded straw material when the biomass was presoaked in acetic acid. High quality pellets with high calorific value (20 MJ/kg), high compression strength (228 kN/m), high density (1300 kg/m3) and low ash content (0,06 %) were produced from sawdust spruce and GROT:Spruce mix used in our study. Based on our results, we can therefore suggest that steam explosion process of lignocellulosic residues improves the quality of the biomass to pellets production and at the same time open for the possibility to produce value-added chemicals.

Factors influencing yield, chemical composition and efficacy of essential oils

Essential oils are secondary metabolites that are produced by plants for the purpose of protection from pests, predators, attraction of pollinators and seed dispersal. The oil is produced in different parts of the plants and contains various chemical compounds that give plants a characteristic odour and flavor. These compounds vary between different plant species and also within plants of the same species. The yield and the efficacy of essential oils also vary between and within species. The variations in the essential oil compounds, the yield and the efficacy is influenced by both exogenous and endogenous factors. Endogenous factors such as plant age, plant density, plant genotype, part of the plant where the oil is extracted brings about variability in yield, chemical composition and the efficacy of essential oils. Similarly, exogenous factors such as light intensity and temperature, water availability, altitude and latitude, soil type and composition, preparation of the plant material before the essential oil extraction, method of extraction of the essential oil and the storage conditions after extraction also have a great influence on the chemical composition, yield and efficacy of essential oils. The factors then need to be moderated in order to ensure that the essential oil produced is of the quality required. Once extraction is done, proper storage conditions to avoid oxidation is necessary as the essential oils await to be used. They should be stored in dark cool conditions in tightly closed dark glass containers to ensure long term quality. Knowledge on the growth requirements of the individual plants that produce oils is necessary so as to produce quality oil.

EFFECTS OF ORGANIC AND INORGANIC FERTILIZERS ON SOIL CHEMICAL PROPERTIES AND THE YIELD OF Amaranthus species IN A CONTINUOUSLY CROPPED ULTISOL

Field and laboratory experiments were conducted to evaluate the effects of poultry manure and NPK (20:10:10) fertilizer on soil chemical properties and yield of Amaranthus species. The treatments were: T1-Control (no fertilizer), T2-NPK 20:10:10 (200kg/ha), T3-Poultry manure (5 tons/ha), T4-NPK 20:10:10 (100kg/ha) + Poultry manure (2.5 tons/ha), T5-NPK 20:10:10 (100kg/ha)+ Poultry manure (5 tons/ha), T6-NPK 20:10:10 (200kg/ha)+ Poultry manure (5 tons/ha. The experiments were laid out in a randomized complete block design (RCBD). The soil was strongly acidic, having a pH of 5.1 and low in % total Nitrogen (0.10), % organic carbon (1.13) and the exchangeable bases. From the study, the poultry manure 5t/ha + NPK (20:10:10) 100kg/ha gave the best yield of Amaranthus species, followed by poultry manure 5t/ha + NPK (20:10:10) 200kg/ha which gave an increase in soil chemical properties. It is recommended that the combination of poultry manure 5t/ha + NPK (20:10:10) 100kg/ha fertilizer could be used for profitable Amaranthus production in the study area.

Estimating cardiac mechanical efficiency in a porcine ex situ working heart model

We introduce a method for assessing cardiac mechanical efficiency via a porcine ex situ biventricular working heart model, designed to closely replicate physiological conditions and improve the evaluation of donor heart viability for transplantation. The method aims to provide decision support for the safe utilization of hearts that might otherwise be discarded. Quantifying the heart's pumping work against its chemical energy yield, our model advances traditional assessments by incorporating dynamic flow impedances to simulate real-world cardiac loads. We calculate mechanical efficiency by measuring aortic pressure, cardiac output, coronary flow, and blood-gas parameters in six porcine hearts beating in isolation, outside of the body, against computer-controlled dynamic flow impedances. The observed mean mechanical efficiency was 8.0±0.8% (standard error of the mean), below the physiological norm of 25%. This discrepancy underscores the influence of ex situ conditions on heart performance, as well as the limitations of standard estimation methods. Impacts of the ex situ setup as well as estimation improvements are discussed. Future research will explore integrating imaging technologies (MRI) to refine mechanical efficiency assessment.

Stereoselective synthesis of 6/7/6-fused heterocycles with multiple stereocenters via an internal redox reaction/inverse electron-demand hetero-Diels-Alder reaction sequence.

A highly stereoselective synthesis of fused heterocycles with multiple stereocenters via an internal redox reaction/inverse electron-demand hetero-Diels-Alder (IEDHDA) reaction sequence is described. The present reaction sequence has three interesting features: (1) complete control of two potentially competitive processes, i.e., hetero-Diels-Alder reaction and [1,5]-hydride shift; (2) one-shot construction of the complicated 6/7/6-fused heterocyclic structure having multiple stereocenters; and (3) high control of its stereoselectivity. When alkenylidene barbiturates with an allyl benzyl ether moiety were treated with a catalytic amount of Sc(OTf)3 and 2,2'-bipyridine, the internal redox reaction/IEDHDA reaction proceeded successively to afford 6/7/6-fused heterocycles in good chemical yields with good to excellent diastereoselectivities.

Divergent synthesis of multi-substituted phenanthrenes via an internal redox reaction/ring expansion sequence.

We report an effective synthetic route to multi-substituted phenanthrenes via an internal redox reaction/ring expansion sequence. The interesting feature of the present system is that it allows for the divergent synthesis of the target skeleton depending on the selected Lewis acid catalyst. When benzylidene malonates with a cyclic structure at the ortho-position were treated with BF3·OEt2, three sequential processes (internal redox reaction/elimination of the alkoxy group/ring expansion) proceeded to give phenanthrene derivatives in which the alkoxycarbonyl (CO2R) group and the alkyl (R) group were in close proximity to each other, in good chemical yields. In sharp contrast, treatment with Bi(OTf)3 exclusively led to the formation of another type of phenanthrene, whose R group was positioned distal to the CO2R group.

Organocatalytic enantioselective decarboxylative protonation of α-alkyl-α-aryl malonate monoesters.

In contrast to the well-established enzymatic enantioselective decarboxylative protonation (EDP), the corresponding chemocatalytic reactions of acyclic malonic acid derivatives remain challenging. Herein, we developed a biomimetic EDP of α-alkyl-α-aryl malonate monoesters using a chiral 1,2-trans-diaminocyclohexane-based N-sulfonamide as an organocatalyst. The method demonstrates excellent chemical yields, good enantioselectivity, mild reaction conditions, and the generation of only CO2 as waste.

A Comprehensive Biogeochemical Assessment of Climate‐Threatened Glacial River Headwaters on the Eastern Slopes of the Canadian Rocky Mountains

AbstractClimate change is driving the loss of alpine glaciers globally, yet investigations about the water quality of rivers stemming from them are few. Here we provide an overview assessment of a biogeochemical data set containing 200+ parameters that we collected between 2019 and 2021 from the headwaters of three such rivers (Sunwapta‐Athabasca, North Saskatchewan, and Bow) which originate from the glacierized eastern slopes of the Canadian Rocky Mountains. We used regional hydrometric data sets to accurately model discharge at our 14 sampling sites. We created a Local Meteoric Water Line (LMWL) using riverine water isotope signatures and compared it to collected regional rain, snow, and glacial ice signatures. Principal component analyses of river physicochemical measures revealed distance from glacier explained more data variability than other spatiotemporal factors (i.e., season, year, or river). Discharge, chemical concentrations, and watershed areas were then used to model site‐specific open water season yields for 25 parameters. Chemical yields followed what would generally be expected along river continuums from glacierized to montane altitudinal life zones, with landscape characteristics driving chemical sources and sinks. For instance, particulate chemical yields were generally highest near source glaciers with proglacial lakes acting as settling ponds, whereas most dissolved yields varied by parameter and site. As these headwaters continue to evolve with glacier mass loss, the data set and analyses presented here can be used as a contemporary baseline to mark future change against. Further, following this initial assessment of our data set, we encourage others to mine it for additional biogeochemical studies.

Self-Standing Metal Foam Catalysts for Cathodic Electro-Organic Synthesis.

Although electro-organic synthesis is currently receiving renewed interest because of its potential to enable sustainability in chemical processes to value-added products, challenges in process development persist: For reductive transformations performed in protic media, an inherent issue is the limited choice of metallic cathode materials that can effectively suppress the parasitic hydrogen evolution reaction (HER) while maintaining a high activity toward the targeted electro-organic reaction. Current development trends are aimed at avoiding the previously used HER-suppressing elements (Cd, Hg, and Pb) because of their toxicity. Here, this work reports the rational design of highly porous foam-type binary and ternary electrocatalysts with reduced Pb content. Optimized cathodes are tested in electro-organic reductions using an oxime to nitrile transformation as a model reaction relevant for the synthesis of fine chemicals. Their electrocatalytic performance is compared with that of the model CuSn7Pb15 bronze alloy that has recently been endorsed as the best cathode replacement for bare Pb electrodes. All developed metal foam catalysts outperform both bare Pb and the CuSn7Pb15 benchmark in terms of chemical yield and energetic efficiency. Moreover, post-electrolysis analysis of the crude electrolyte mixture and the cathode's surfaces through inductively coupled plasma mass spectrometry (ICP-MS) and scanning electron microscopy (SEM), respectively, reveal the foam catalysts' elevated resistance to cathodic corrosion.

Degradation of micropollutants by gamma irradiation: Insight of transformation product formation explored by suspect and non-target screening using LC-HRMS

Conventional wastewater treatment systems have limitations in removing diverse micropollutants present with the complex matrix. As an alternative, advanced oxidation processes such as gamma-irradiation have been proposed. The aim of the study was to get insight into the decomposition of persistent pharmaceuticals (carbamazepine, cetirizine, tramadol) by gamma irradiation in pure water and effluent, and the formation and pathway of transformation products (TPs) identified via suspect/non-target screening using LC-HRMS. For TPs, the environmental risk assessment was also conducted with Quantitative Structure Activity Relationship (QSAR) based estimations. The decomposition effect was estimated with the removal rate and radiation chemical yield (G-value). The results indicated that the removal rate increased as the absorbed dose increased, up to 5 kGy, completely eliminating the target pharmaceuticals (initial nominal concentration: 10 mg/L) in pure water. However, the degradation in effluent was negatively affected by the organic matrix. By employing suspect/non-target screening techniques, a tentative identification of 30 transformation products (TPs) was achieved, providing insights into the degradation pathway. They were mainly formed through hydroxylation reaction by OH⸱. As a result of the QSAR estimation for the hazard of TPs, most of the TPs showed a lower risk than the parent compound. It indicates that the gamma-irradiation can be used as an alternative process to eliminate hardly degradable micropollutants in conventional wastewater treatment plant in a way to mitigate the environmental risk.

Red-Emissive Center Formation within Carbon Dots Based on Citric Acid and Formamide.

The formation of red-emissive optical centers in carbon dots based on citric acid and formamide was investigated by varying the synthesis parameters with focus on finding optimal─necessary and sufficient─amount of precursors to decrease byproduct amount and to increase the chemical yield of red-emissive carbon dots. The emission is observed at 640 nm excited at 590 nm and quantum yield reaches up 19%. A high chemical yield of carbon dots of 26% was achieved at an optimal molar ratio of citric acid to formamide of 1:4.

Synthesis, characterization, optical properties, and solvatochromism of highly fluorescent benzotriazolyl vinyl aniline based D-π-A fluorophores

Two solvatochromic benzotriazolyl vinyl aniline derivatives have been synthesized via the Krapcho decarboxylation with chemical yields of 43% and 47%. Single crystal X-ray diffraction confirmed that the (E)-isomer was preferentially obtained. Experimental and theoretical studies were performed for both compounds. Photophysical properties were evaluated: in solution fourteen solvents were used and quantum yields of 15.8–34.0% were reached, and in thin films, a bathochromic phenomenon was observed. DFT calculations were also performed to analyze the electronic properties and cyclic voltammetry helped to evaluate the behavior of both compounds in thin films. Furthermore, the compounds were employed in a concept test to study their application in OLED devices.

Kraft Lignin Electro-Oxidation under Ambient Temperature and Pressure

Lignin is the largest natural source of aromatic chemicals. Due to its complex polymeric structure, Kraft lignin is under-utilized and usually combusted for heat generation, thus resulting in CO2 emissions in the Kraft process. To valorize lignin with renewable electricity and to convert it into value-added aromatic chemicals, efficient electrochemical methods need to be discovered, based not only on its apparent yield of building block chemicals but also on its energy efficiency. In this study, the electro-oxidative performance of six different metals was systematically evaluated. The results showed that the synthesized Ni-based catalyst can increase the vanillin and vanillic acid apparent yield by 50–60% compared to when Ni-based catalyst is absent. We also found that the oxygen evolution reaction (OER) is more than a competing reaction since the presence of oxygen synergistically aids oxidation of the lignin to increase aromatic chemical production by 63% compared to the sum of vanillin generation from both voltage-only and oxygen-only scenarios. With the novel proposed notion of charge efficiency, we showed that utilizing a thinner layer of Ni catalyst balances the OER and the oxidative reaction of lignin, thus improving the charge efficiency for vanillin by 22%

Copper(I)-Photocatalyzed Diastereoselective Aziridination of N-Sulfonyl Imines with Vinyl Azides: Application to Benzo[f][1,2,3]oxathiazepines Dioxides and Fused Isoxazolines.

An in situ generated photoactive copper(I)-complex-catalyzed aziridination reaction of cyclic N-sulfonyl imines with α-aryl-substituted vinyl azides irradiated by blue-LEDs light is reported for the first time. This novel SET process represents a mild, sustainable, and pragmatic method for accessing synthetically resourceful sulfamidate-fused aziridines in acceptable chemical yields with excellent diastereoselectivities. Delightedly, pharmacologically attractive benzo[f][1,2,3]oxathiazepine dioxides and fused isoxazoline frameworks were achieved through our newly developed metal-free based ring-expansion techniques, highlighting the synthetic value of accessed aziridines. Finally, the possible mechanism for [2+1] aza-cyclization was presented based on the conduction of a series of control experiments.

Synthesis and structural characterization of benzene-1,3-disulfonamide-containing 11- to 13-membered heterocycles via double Mitsunobu annulation

Abstract The synthesis and 3D-conformation of several novel benzene-1,3-disulfonamides-containing 11- to 13-membered heterocycles have been achieved. Double Mitsunobu annulation was effective for the construction of medium to large ring systems in moderate chemical yields. In addition, the flexibility of sulfonamide moieties in these rings was determined by X-ray crystal structural analysis.

Donepezil‐indolyl hybrids as multipotent cholinesterase/monoamine oxidase inhibitors for the potential treatment of Alzheimer’s disease

AbstractBackgroundNumerous laboratory and clinical studies have evidenced that MAO‐B inhibitors are a potential therapeutic approach for the treatment of AD. Thus, drugs used to inhibit activated MAO, including rasagiline, ladostigil and selegiline, may provide neuroprotection against AD by improving cognitive impairment, modulating the proteolytic cleavage of APP and decreasing levels of Aβ protein fragments that accumulate in the brain. Future clinical studies on MAO inhibitors for the treatment of AD may provide further insights into the mechanism of action of antioxidants as therapeutic agents for AD.MethodSeries of donepezil‐indolyl hybrids were prepared and characterized via highresolution mass spectrometry, 1H nuclear magnetic resonance and 13C nuclear magnetic resonance techniques. In vitro fluorometric assay (by Amplex® UltraRed reagent to detect hydrogen peroxide or peroxidase activity in biological samples or enzymes.) was used to investigate the activity of the synthesized compounds on both MAO‐A and MAO‐B isozymes as well as acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) by Ellman method with modifications.ResultThe biological evaluation of molecules 1‐30 showed that most of these compounds are potent, in the nanomolar range, and selective AChEI, with moderate and equipotent selectivity for MAO‐A and MAO‐B inhibition. In overall, compound 11, as a potent and selective dual AChEI, showing a moderate MAO inhibitory profile, can be considered as an attractive multipotent drug for further development on two key pharmacological targets playing key roles in the therapy of Alzheimer’s disease.ConclusionThe pharmacological profile of compound 11, as well as the fact that it is a readily available compound in a short synthetic sequence, in good chemical yields, prompts us to select it as a lead‐compound for further optimization in our current research programme targeted to the preparation of new molecules for the potential treatment of AD.

Impact of silicate fertilizer on soil properties and yield of bread wheat in Nitisols of tropical environment

PurposeSoil acidity and depletion of essential plant nutrients are among the major abiotic stresses that constrained wheat productivity in Ethiopia. Silicates and silicate by-products can be used as alternative source for amendment of soil acidity and improvement of crop yields. Surface application of water-soluble silicate fertilizer alone and the integrated application with full does of recommended N and P from mineral fertilizers can reduce the extent of soil acidity and improve phosphorous availability in the soil, soil pH and exchangeable acidity and can enhance the yield attributes and yield of bread wheat. A field experiment was conducted under rain-fed condition from July to December of 2020 to evaluate the role of soil and foliar application of water-soluble silicate fertilizer without and with reduced or full doses of recommended nitrogen (N) and phosphorus (P) (RNP) from mineral fertilizers on soils chemical attributes, yield components and yield of bread wheat sown under moderately to strongly acidic condition in southeastern Ethiopia. MethodsThe experiment comprised sole silicate (40 kg + 18 L/ha−1), and its integration with full dose of RNP (92–30 kg N–P ha−1), three quarters dose of RNP (69–23 kg N–P ha−1) and half dose of RNP (46–15 kg N–P ha−1) from mineral fertilizers. Full dose of RNP from mineral fertilizers and a negative control with no silicate and mineral fertilizer inputs included as controls, resulting in a total of six treatments. The experiment was laid out in randomized complete block design, replicated three times. ResultsThe combined application of silicate with mineral fertilizers significantly influenced soil properties, yield attributes and yield of bread wheat. Integrated applications of silicate fertilizers and full dose of RNP increased grain yield, biomass yield, and available soil P by 108, 115, and 23 % respectively relative to untreated soil. ConclusionsIntegration of silicate with mineral fertilizers can be considered as a viable and alternative option for acid soils amendment. Generally, the result of the current study revealed that combined application of water soluble granular and liquid silicate at the rate of (40 kg + 18 L)/ha with full dose of recommended nitrogen (92 kg ha−1) and phosphorus (30 kg ha−1) significantly reduced exchangeable acidity, tended to increase soil reaction, increased available soil phosphorus content and boosted yield of bread wheat compared to their sole applications. Thus, application of water-soluble silicate fertilizer with recommended rate of nitrogen and phosphorus is better in enhancing plant nutrition and yield of bread wheat in the highlands of Ethiopia and other similar agro-ecologies.

Promiscuous Yet Specific: A Methionine-Aromatic Interaction Drives the Reaction Scope of the Family 1 Glycosyltransferase GmUGT88E3 from Soybean.

Family 1 glycosyltransferases (GT1s, UGTs) catalyze the regioselective glycosylation of natural products in a single step. We identified GmUGT88E3 as a particularly promising biocatalyst able to produce a variety of pure, single glycosidic products from polyphenols with high chemical yields. We investigated this particularly desirable duality toward specificity, i.e., promiscuous toward acceptors while regiospecific. Using high-field NMR, kinetic characterization, molecular dynamics simulations, and mutagenesis studies, we uncovered that the main molecular determinant of GmUGT88E3 specificity is a methionine-aromatic bridge, an interaction often present in protein structures but never reported for enzyme-substrate interactions. Here, mutating Met127 led to inactive proteins or 100-fold reduced activity.

Study of Correlation between Soil Chemical Properties, Zinc Fractions and Yield of Rice under Long Term Fertilization in Chromustert Soil

Study of Correlation between Soil Chemical Properties, Zinc Fractions and Yield of Rice under Long Term Fertilization in Chromustert Soil

An Investigation into the Effects of Organic Amendments in a Saline Environment on Soil Chemical Characteristics, Growth, and Yield of Rice in the South of Senegal

Context of the Study: The use of organic amendments could help increase the resilience of lowland rice in Lower Casamance to salinity. The aim of this study was to test the effect of different organic amendments (biochar and compost) on the salinity tolerance of lowland rice in Basse Casamance.
 Objective: The aim was to test the effect of different organic amendments on the salinity tolerance of rice in the lowlands of the villages of Selecky and Essyl in Lower Casamance.
 Methodology: A split-plot design was adopted with two factors: the type of organic amendment with 4 treatments (biochar, compost, compost + biochar and the control) and salinity with two treatments (salted and unsalted zones). These treatments were repeated 3 times in two consecutive years, 2020 and 2021, at the Selecky and Essyl sites. Physico-chemical characteristics as well as rice growth and production parameters were studied.
 Results: In the saline zone, soil amendments significantly increased the number of tillers and the height of rice plants compared with controls (p<0.05). Average rice yield and plant biomass were significantly higher in the amended plots at Selecky in both experimental years (p<0.05). At Essyl, on the other hand, height, number of tillers, rice yield and plant biomass were lower in the 2nd year of experimentation. Organic amendments had a significant effect (p<0.05) on rice production and yield parameters in the salt zone.