Fast Step Research Articles

Fast and efficient single step synthesis of modified magnetic nanocatalyst for catalytic reduction of 4-nitrophenol

In this work, asparagine chitosan magnetic nanoparticles (ACMNPs) have been synthesized in single step using reduction-precipitation method. The synthesized nanoparticles were characterized using FTIR, SEM, HR-TEM, EDX, TGA, VSM, XRD and UV–Vis techniques. The shape of nanoparticles found was spherical as well as semi-spherical and the size obtained through HRTEM was 6.0–7.5 nm. EDX analysis showed the presence of elements such as carbon, nitrogen, oxygen, iron which confirmed the modification. The magnetic nanoparticles were found to be sufficiently magnetic as saturated magnetization value obtained with the help of VSM was 19.4 emu/g. The synthesized nanoparticles were applied for catalytic reduction of a toxic organic pollutant 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) which has industrial and medical application. 4-Nitrophenol converted to 4-nitrophenolate ion in presence of NaBH4 as reducing agent. On addition of ACMNPs nanocatalyst the 4-nitophenolate quickly converted to 4-aminophenol as confirmed by the color change from yellow to colorless in few minutes. The effect of parameters like amount of catalyst (10–25 mg) and temperature (25–55 °C) on time of catalysis were also evaluated. The results obtained showed that increasing both the amount of catalyst and temperature enhanced the catalysis rate. Increasing the amount of catalyst from 10 to 25 mg reduces the time of catalysis from 18 min to 6 min, while increasing the temperature from 25 °C −55 °C, reduces the catalytic time from 9 min to 4 min with 20 mg of nanocatalyst. The rate constant K1 and activation energy obtained were 0.4681 min−1 and 24.03 kJ mol−1 respectively. Furthermore, the reusability of nanocatalyst was also studied and it was found that easy separation of magnetic nanocatalyst with the help of external magnet enhanced its reusability and the catalyst showed good reusability of up to 3 cycles.

Developing Disaster Mitigation Education with Local Wisdom: Exemplified in Indonesia Schools

In vulnerable disaster-geographical condition in ring of fire, schools in Indonesia have conducted innovation of disaster mitigation education recent years. A disaster mitigation model in Indonesia is the use of local wisdom. Local wisdom-based disaster education aims as grand design during learning process and it supports the formation of student resilience. Therefore, to revive the value of local wisdom, it needs reinterpretation through adaptation of local knowledge and revitalization of contemporary conditions as innovations in disaster risk reduction. Through the integration of local wisdom based on disaster mitigation curriculum in the learning process, it is expected to be able to take fast, precise and accurate steps in dealing with disasters that occur in every region in Indonesia.

Hydrothermal carbonization of household wet waste – characterization of hydrochar and process wastewater stream

In the present study, household wet waste (HWW) pretreatment was explored using hydrothermal carbonization (HTC) to enhance resource recovery opportunities. The pretreatment was performed at 200 °C for 1–8 h duration in a 2 L high pressure reactor. After HTC, the recovered solid hydrochar (HC) showed high calorific value of ∼ 27 MJ/kg compared to 18 MJ/kg of HWW. Moreover, it contained significant amount of oxygen containing acidic functional groups, hence the waste derived HC may also be utilized as adsorbent in wastewater treatment and soil conditioner. The process wastewater (PW) contained several value-added organics including proteins and furfurals. The HTC reaction kinetics showed the conversion of HWW to primary HC as the fastest step (rate constant = 0.0126 min−1). Moreover, the biochemical methane potential test on PW revealed generation of significant amounts of biogas with 55–75% methane. The total energy production from HC and PW was estimated as ∼ 3.3 MJ/kg of HWW.

Stochastic estimation of total radiated power from PCB signal/PDN layout using EMI radiation resistance

In this article, a stochastic model is proposed for estimation of electromagnetic radiated emission from printed circuit board (PCB) layout. Considering the arbitrary nature of the PCB layout by radiation resistance, the radiated power density is estimated analytically. The model employs stochastic passing signals as layout trace excitation. The approach is conducted on a designed and fabricated test board. The total radiated power from the PCB layout can be as high 11.5 nW in 2.4GHz–2.5 GHz and 2.8uW in 1 MHz to 3 GHz. An important achievement of the model is its fast estimation of total radiated power for a given PCB layout, rather time/cost consuming experimental measurements and software simulations. For the designed test board, the full-wave simulation time lasts 5 h, while the proposed mathematic model gives the result within 30s on a device with Intel Core i5 processor and 8 GB RAM. The approach can be considered as a fast and preliminary verification step in estimation of radiated emission from PCB layout.

Full Kinetics and Mechanism Investigation for Generating 4-Substituted 1, 4- Dihydropyridine Derivatives in the Presence of Green Catalyst and Aqueous Medium: Experimental Procedure.

The main objective of the kinetic investigation of the reaction between ethyl acetoacetate 1, ammoniumacetat 2, dimedone 3, and diverse substitutions of benzaldehyde 4-X, (X= H, NO2, CN, CF3, Cl, CH (CH3)2, CH3, OCH3, OCH3, and OH) for generating 4-substituted 1, 4-dihydropyridine derivatives (product 5) was to recognize the most realistic reaction mechanism. The layout of the reaction mechanism was studied kinetically via a UV-visible spectrophotometry approach. Among the various mechanisms, only mechanism1 (path1) involving 12 steps was recognized as a dominant mechanism (path1). Herein, the reactions between 1 and 2 (kobs= 814.04 M-1.min-1) and also between 3 and 4-H (kobs= 151.18 M-1.min-1) can be accepted as the first and second steps (step1 and step2) of the reaction mechanism, respectively. Amongst all steps, only step9 of the dominant mechanism (path1) comprised substituent groups (X) near the reaction center. Para electron-withdrawing or donating groups on the compound 4-X increased the rate of the reaction 4 times more or decreased 8.7 times less than the benzaldehyde alone. So, this step is sensitive for monitoring any small or huge changes in the reaction rate. Accordingly, step9 is the rate-determining step of the reaction mechanism (path1). The recent result is in agreement with the Hammett description of an excellent dual substituent factor (r = 0.990) and positive value of reaction constant (ρ= +0.9502), which confirms that both the resonance and inductive effects "altogether" contribute to the reaction center of step9 in the dominant mechanism (path1).

A Huygens' surface approach to rapid characterization of peripheral nerve stimulation.

Purpose:Peripheral nerve stimulation (PNS) modeling has a potential role in designing and operating MRI gradient coils but requires computationally demanding simulations of electromagnetic fields and neural responses. We demonstrate compression of an electromagnetic and neurodynamic model into a single versatile PNS matrix (P-matrix) defined on an intermediary Huygens’ surface to allow fast PNS characterization of arbitrary coil geometries and body positions.Methods:The Huygens’ surface approach divides PNS prediction into an extensive precomputation phase of the electromagnetic and neurodynamic responses, which is independent of coil geometry and patient position, and a fast coil-specific linear projection step connecting this information to a specific coil geometry. We validate the Huygens’ approach by performing PNS characterizations for 21 body and head gradients and comparing them with full electromagnetic-neurodynamic modeling. We demonstrate the value of Huygens’ surface-based PNS modeling by characterizing PNS-optimized coil windings for a wide range of patient positions and poses in two body models.Results:The PNS prediction using the Huygens’ P-matrix takes less than a minute (instead of hours to days) without compromising numerical accuracy (error ≤ 0.1%) compared to the full simulation. Using this tool, we demonstrate that coils optimized for PNS at the brain landmark using a male model can also improve PNS for other imaging applications (cardiac, abdominal, pelvic, and knee imaging) in both male and female models.Conclusion:Representing PNS information on a Huygens’ surface extended the approach’s ability to assess PNS across body positions and models and test the robustness of PNS optimization in gradient design.

Dynamic security assessment for the power system in the presence of wind turbines

Dynamic security is an essential requirement for operating a modern power system. Due to the global increase in load demand, modern power systems witness several dramatic changes in terms of size and implementation of new renewable sources. At the same time, the deregulation process in power operation policy is being pushed to operate closer to its security boundary limits. Based on the combined Decision Tree (DT) algorithm, namely Random Forest (RF) and advance attribute selection technique, this paper presents an approach to address these challenges related to dynamic security assessment (DSA) in the modern power system. The performance of study approach is demonstrated on a modified version of IEEE 9 and 14-bus test system models with presence of two wind turbines (WTs) type WTG 3. Results show the superiority of RF compared to other DT algorithms that are used in this study. In addition, the attribute selection technique could significantly affect the number of attributes required for DSA. This makes DT classifier more effectiveness in the online application. Thus, this approach can provide control center with vital information with high accuracy results and less attributes about security state direction that will help operator to take the right and fast steps to remedy problems and prevent a blackout from occurring.

The ‘Surprise question’ in heart failure: a prospective cohort study

ObjectiveThe Surprise Question (SQ) is a prognostic screening tool used to identify patients with limited life expectancy. We assessed the SQ’s performance predicting 1-year mortality among patients in ambulatory heart...

A bionic soft tongue driven by shape memory alloy and pneumatics

Soft grippers have exhibited considerable advantages owing to their flexible deformation, compliant operation, and safe interaction with objects. The ability to grip solid and liquid objects can greatly expand the application range of the soft grippers. Dogs stick out their tongues and then curl them backward to form a ladle shape for eating food and drinking water. The large extension ratio and the ladling motion of the tongues endow dogs with flexible operations for both solids and liquids. In this work, inspired by both the extending and ladling motions of dog tongues, a bionic soft tongue with the capability of handling solid and liquid objects was designed. The bionic soft tongue was composed of a tongue base and a tongue tip, which were driven by pneumatics and shape memory alloy wires, respectively. The tongue base was capable of linearly elongating and contracting with a considerable scale, while the tongue tip could be curled into a ladle shape to grasp objects. The dynamic model of the tongue base was developed and then extended to build the model-based feedback controller for the motion control. A phase dynamic model of the tongue tip was simulated for structural optimization. With the model-based feedback controller, the bionic soft tongue could achieve a fast step response and precise position control. Experimental results showed that the bionic soft tongue could grasp different kinds of objects, including of water, rice, and gel balls. This work is expected to expand the application scope of soft grippers.

Fast and efficient single step liquid chromatography separation of parent homopolymers from block copolymers

The modified layout of the barrier method called liquid chromatography under limiting conditions of enthalpic interactions is presented. It enables automated quantitative separation of blends of synthetic polymers, for example the single step discrimination of both parent homopolymers from the block copolymers. Moreover, this method enables the estimation of molar mass and molar mass distribution of the block copolymer precursor. Adjacent large sequences of mobile phase of different composition are applied as barriers. They are created by a computer controlled pair of pumping systems in the form of longitudinal profiles along the column. The home synthesized block copolymers polystyrene-block-poly(2-vinylpyridine) served as model examples of the method application. The adsorption retention mechanism was exploited using mesoporous bare silica gel column packing. Series of block copolymers of similar composition can be quickly handled with the method to optimize their synthesis.

Environmental Hazards of Boron and Vanadium Nanoparticles in the Terrestrial Ecosystem-A Case Study with Enchytraeus crypticus.

From the start of the 21st century, nanoecotoxicological research has been growing in fast steps due to the need to evaluate the safety of the increasing use of engineered nanomaterials. Boron (B) and vanadium (V) nanoparticles (NPs) generated by anthropogenic activities are subsequently released in the environment; therefore, organisms can be continuously exposed to these NPs for short or long periods. However, the short and long-term effects of BNPs and VNPs on soil organisms are unknown. This work aimed to recognize and describe their potential toxicological effects on the model species Enchytraeus crypticus, assessing survival and reproduction, through a longer-term exposure (56 days (d)—OECD test extension of 28 d), and avoidance behavior, through a short-term exposure (48 hours (h)). After 28 d, BNPs did not induce a significant effect on E. crypticus survival, whereas they decreased the organisms’ reproduction at 500 mg/kg. From 10 to 500 mg/kg, VNPs decreased the E. crypticus survival and/or reproduction. After 56 d, 100 to 500 mg/kg BNPs and 50 to 500 mg/kg VNPs, decreased the reproduction output of E. crypticus. The estimated Effect Concentrations (ECx) based on reproduction, for BNPs, were lower at 56 d compared with 28 d; for VNPs, an opposite pattern was found: ECx 28 d < ECx 56 d. BNPs did not induce an avoidance behavior, but organisms avoided the soil contaminated with 10 mg VNPs/kg. The tested NPs showed different E. crypticus apical effects at 28 d from the ones detected at 56 d, dependent on the type of NPs (B vs. V). In general, VNPs showed to be more toxic than BNPs. However, the effects of VNPs were alleviated during the time of exposure, contrarily to BNPs (which became more toxic with extended duration). The present study adds important information about NPs toxicity with ecological significance (at the population level). Including long-term effects, the obtained results contributes to the improvement of NPs risk assessment.

Iron phthalocyanine-catalyzed radical phosphinoylazidation of alkenes: A facile synthesis of β-azido-phosphine oxide with a fast azido transfer step

Phosphinoylazidation of alkenes is a direct method to build nitrogen- and phosphorus-containing compounds from feed-stock chemicals. Notwithstanding the advances in other phosphinyl radical related difunctionalization of alkenes, catalytic phosphinoylazidation of alkenes has not yet been reported. Here, we describe the first iron-catalyzed intermolecular phosphinoylazidation of styrenes and unactivated alkenes. The method is practically useful and requires a relatively low loading of catalyst. Mechanistic studies confirmed the radical nature of the reaction and disclosed the unusually low activation energy 4.8 kcal/mol of radical azido group transfer from the azidyl iron(III) phthalocyanine species (PcFeIIIN3) to a benzylic radical. This work may help to clarify the mechanism of iron-catalyzed azidation, inspire other mechanism studies and spur further synthetic applications.

Kinetics of thermal decomposition of the polyester nanocomposites

In this study, characterization processes have been done by synthesizing the nano-aerosil-reinforced polyester composite. Chemical bonds formed in polyester composites were examined with FTIR spectrum and thermal stability with proportional integral derivative (PID) system. With the PID system, the drying kinetics of nano-polyester composites were examined from room temperature to 378 K, and thermal decomposition kinetics up to 918 K. The effect of temperature separates volatile components and physical impurities from the structure in the first region. Chemical decomposition starts in the second region, and degradation is the fastest step. Thermal degradation slows in the third region, and the remaining cross-linked components shift away from the structure. According to the new special solution method, the most suitable function in the thermal decomposition kinetics of polyester nanocomposites was found in the second-order model (f (δ) = (1–δ)2, E: 53.492 kJ/mol, R 2: 0.99686, for experiment 3). Also, with three-dimensional diffusion and Jander functions have been found better results using Coats-Redfern method (R 2: 0.99882, E: 50.55141 kJ/mol for experiment 3). The most consistent results in drying kinetics of polyester nanocomposites were found in the Midilli and Kucuk model (R 2: 0.99575, RMSE: 0.03099 for experiment 1).

Micro-Kinetic Modelling of the Electro-Oxidation of Methanol on Platinum

Methanol electro-oxidation reaction is a widely studied system due to its applicability in electrochemical devices for energy conversion, such as direct methanol fuel cells. Nevertheless, the effect of some kinetic parameters on the overall reaction rate is still unclear and the reaction mechanism is controversial. Herein we investigate the electro-oxidation of methanol on platinum by means of a micro-kinetic approach using the mean-field approximation. The resulting model, c.f. Figure 1, is based on data, namely spectroscopic and electrochemical, available in the literature, and translated into a set of ordinary differential equations. Simulations are carried out in comparison with experimental results, including cyclic voltammetry, chronamperometry and potential oscillations under galvanostatic control. The numerical simulations agree satisfactorily with the experimental results with a set of realistic reaction rates in the elemental reaction steps for the electrooxidation of methanol in platinum. The values of the rate coefficients show the adsorption of methanol and the first steps after the formation of formic acid as the fastest, while the desorption of bridge adsorbed formic acid and the chemical adsorption and desorption of methylformate as the fastest steps. Figure 1

In situ growth of copper-based metal-organic framework on a helical shape copper wire as a sorbent in stir-bar sorptive extraction of fenthion followed by corona discharge ion mobility spectrometry

In this paper, a helical copper wire, coated with copper-benzene-1,4-dicarboxylic acid metal-organic framework (Cu-BDC) was used as a sorbent for stir-bar sorptive extraction of fenthion from water and fruit samples. The homogenous coating was fabricated through two simple and fast steps. The chemical conversion of copper substrate to copper hydroxide nanotubes (Cu(OH)2 NTs) was performed in an alkaline solution and then Cu-BDC was formed through a neutralization reaction. Corona discharge ion mobility spectrometry in positive mode was applied for the detection of fenthion. To improve the sensitivity of the method, some synthesis and extraction parameters affecting the extraction efficiency such as benzene-1,4-dicarboxylic acid concentration, ionic strength, sample pH, stirring rate, extraction temperature, and extraction time were investigated. The linear dynamic range between 0.5 and 80 μg L−1 and detection limit of 0.1 μg L−1 were obtained under optimal conditions. The intra- and inter-day relative standard deviations were less than 6.4 and 8.6%, respectively. The applicability of the method was examined for the analysis of different samples (i.e., well water, agricultural wastewater, and orange). The recovery for the determination of fenthion in spiked samples varied from 88 to 111%.

Bimolecular quenching of tryptophan fluorescence in a membrane protein: Evolution of local solvation and environment during folding into a bilayer

Fluorescence spectroscopy, including Stern-Volmer quenching, is a valuable tool for the study of protein dynamics. Changes in protein solvation during the folding reaction of a membrane protein, Outer membrane protein A (OmpA), into lipid bilayers was probed with bimolecular fluorescence quenching with acrylamide quencher. Six single-tryptophan OmpA mutants (W7, W15, W57, W102, W129, and W143) allowed for site-specific investigations at varying locations within the transmembrane β-barrel domain. A sphere-of-action quenching model that combines both static and dynamic components gave rise to Stern-Volmer quenching constants, KD, for OmpA denatured in 8.0 M urea, aggregated in 0.5 M urea, adsorbed onto small unilamellar vesicles (SUVs), and folded in SUVs (t = 6 hrs). The average KD values were KDdenatured(6.4M-1)>KDaggregated5.9M-1>KDadsorbed(1.9M-1)>KDfolded(0.6M-1). With knowledge of the fluorescence lifetimes in the absence of quencher, the bimolecular quenching constants, kq, were derived; the evolution of kq (and therefore KD)during the folding reaction into SUVs (t = 0 hr to t = 6 hrs) revealed desolvation timescales, τdesolv of 41–46 min (W7, W15, W57, W102), 27 min (W129), and 15 min (W143). The evolution of λmax during folding revealed fast and slow components, τenvironmentfast and τenvironmentslow of 7–13 min and 25–84 min, respectively, for all mutants. For the five lipid- facing mutants (W7, W15, W57, W129, and W143), the general trend was τenvironmentfast7-13min<τdesolv15-46min≤τenvironmentslow(25-84min). These results suggest that there is an initial fast step in which there is a large change in polarity to a hydrophobic environment, followed by a slower desolvation process during evolution within the hydrophobic environment. These results complement previous mechanisms of concerted folding and provide insights into site-specific changes in solvation during formation of native β-barrel structure.

Do Large Vessels Affect Hemodynamic Monitoring by Near Infrared Spectroscopy?

Near Infrared Spectroscopy (NIRS) is a widely used technique to assess local tissue oxygenation and blood volume. However, several confounding factors complicate its interpretation. Among these is the potential influence exerted on NIRS variables by large vessels possibly located within the sample volume. This influence is generally neglected, according to the consideration that infrared light entering a large vessel is completely absorbed and thus not backscattered to the receiving optode. On the other hand, vessel size changes vary the amount of light absorbed and thus should profoundly affect NIRS variables. Aim of this study is to ascertain whether vessel size changes, as produced by venous occlusion, can affect NIRS blood volume indices. NIRS monitoring was performed over the basilic vein (BV) in 12 subjects (9 M – 3 F; age 31±8 yr) simultaneously to ultrasound assessment of BV size at the same location, while a second NIRS probe was positioned on the biceps muscle (BM), over a virtually vessel-free area. The arm was elevated (~60°) to induce vein collapse and subjected to venous occlusion, according to two pressure profiles: slow (from 0 to 60 mmHg in 135 s; plateau, 30 s; deflation to 0 mmHg in 135 s) and fast (step inflation to 40 mmHg maintained for 30 s). The cross-sectional area of the BV was continuously recorded along with a NIRS blood volume indicator, i.e., the total hemoglobin concentration (tHb). The tHb index detected a blood volume increase 1.7 and 2.5 times larger over BV than over BM during both slow (p<0.01) and fast (p<0.01) venous occlusions, respectively. The responses to slow venous occlusion exhibited different time courses: tHbBM exhibited a rather linear rise with time, while tHbBV showed a steeper rise at the beginning of the response, resulting in a higher convexity of the curve (p=0.01), similar to the time course of BV size. Similar patterns could be observed also in response to fast occlusions (p<0.05) and also on THI tracings (p<0.05 for both slow and fast occlusions). On average, tHbBV tracings were better correlated to BV area tracings (r=0.90) than tHbBM (r=0.83, p<0.001, after Z-transform), in response to the slow occlusion. In addition, respiratory oscillations in BV size were observed in tHbBV and not in tHbBM. In conclusion, these results challenge the long standing belief that large vessels are excluded from the NIRS sample volume. Experimental evidence strongly supports the concept that size changes of large vessels may profoundly affect NIRS variables. Neglecting this possibility may potentially introduce relevant artefacts in NIRS variables in all conditions affecting venous blood pressure, such as postural changes, or the extravascular pressure, such as muscle contraction.

New Detection Platform for Screening Bacteria in Liquid Samples.

The development of sensitive methods for the determination of potential bacterial contamination is of upmost importance for environmental monitoring and food safety. In this study, we present a new method combining a fast pre-enrichment step using a microporous cryogel and a detection and identification step using antimicrobial peptides (AMPs) and labelled antibodies, respectively. The experimental method consists of: (i) the capture of large amounts of bacteria from liquid samples by using a highly porous and functionalized cryogel; (ii) the detection and categorisation of Gram-positive and Gram-negative bacteria by determining their affinities toward a small set of AMPs; and (iii) the identification of the bacterial strain by using labelled detection antibodies. As proof of concept, the assessment of the three steps of the analysis was performed by using Escherichia coli and Bacillus sp. as models for Gram-negative and Gram-positive bacteria, respectively. The use of AMPs with broad specificity combined with labelled antibodies enabled the detection and potential categorization of a large spectrum of unknown or unexpected bacteria.

Handling COVID-19 from a Collaborative Governance Perspective in Pekanbaru City

Identical collaborative governance is used in government and must handle COVID-19 to create fast, precise, focused, integrated and synergistic steps between ministries/agencies, local governments, and other stakeholders. This research describes collaborative governance in efforts to deal with COVID-19 in Riau Province, especially Pekanbaru City, considering that the city recorded a relatively high initial increase in cases compared to other areas in Riau Province as well as the implementation of collaborative management. The research method is qualitative, with the type of research used is the exploratory type and literature study. This article analyses several aspects of collaborative governance, namely the initial role of the government, non-state actors, joint decision making, formal organizing, gaining consensus, and the existence of problems to collaborate both on public policies and services.

AutoStepfinder: A fast and automated step detection method for single-molecule analysis

SummarySingle-molecule techniques allow the visualization of the molecular dynamics of nucleic acids and proteins with high spatiotemporal resolution. Valuable kinetic information of biomolecules can be obtained when the discrete states within single-molecule time trajectories are determined. Here, we present a fast, automated, and bias-free step detection method, AutoStepfinder, that determines steps in large datasets without requiring prior knowledge on the noise contributions and location of steps. The analysis is based on a series of partition events that minimize the difference between the data and the fit. A dual-pass strategy determines the optimal fit and allows AutoStepfinder to detect steps of a wide variety of sizes. We demonstrate step detection for a broad variety of experimental traces. The user-friendly interface and the automated detection of AutoStepfinder provides a robust analysis procedure that enables anyone without programming knowledge to generate step fits and informative plots in less than an hour.