Higher Reaction Time Research Articles

Potential of enzymatic process as an innovative technology to remove anticancer drugs in wastewater.

Anticancer drugs are a class of pharmaceutical compounds that have been found in hospital, domestic, and industrial wastewaters and also in surface waters. They have been showing recalcitrance to conventional wastewater treatment technologies and present a potential risk to environment and human health, since they exhibit cytotoxic, teratogenic, and carcinogenic among other effects in higher organisms, even at low concentrations. The presence of these compounds in the environment is a recent challenge for wastewater treatment and some alternative strategies to remove them were already studied, such as white-rot fungi (WRF) technologies. Despite promising results, processes involving fungi are complex, have high reaction times, and require nutrient addition for fungus growth and maintenance. Due to this potential, strategies to make the technology feasible were studied, such as the possibility for direct application of enzymes secreted by WRF. Enzymatic processes were studied in the removal of other pharmaceuticals such as antibiotics, anti-inflammatory, and steroid hormones; however, to the best of our knowledge, there is a gap on literature about their direct action on anticancer drugs.

Preparation and characterization of Cu (II) Schiff base complex functionalized boehmite nanoparticles and its application as an effective catalyst for oxidation of sulfides and thiols

The synthesis, characterization, and evaluation of a Schiff base Cu (II) complex functionalized boehmite nanoparticles (Cu‐complex‐boehmite) as a new catalyst for oxidation of sulfides and thiols in the presence of hydrogen peroxide with complete selectivity and high conversion under solvent‐free and mild reaction conditions were reported. Characterization of the catalyst was performed with various physicochemical methods. This effective catalyst was evaluated in terms of activity and reusability. It indicated high catalytic activity, good recoverability and reusability, and supplied the corresponding products in high yields and short reaction times. In addition, it shows notable advantages such as simplicity of operation, heterogeneous nature, easy work up, and it could be used at least eight times with no significant loss of its activity.

Utilization of oil palm fronds for bio-oil and bio-char production using hydrothermal liquefaction technology

Hydrothermal liquefaction technology carried out on local Malaysian oil palm fronds (OPF) in a batch autoclave reactor to produce solid bio-char as well as liquid bio-oil is reported in this study. The parameters taken in consideration for study encapsulated variable reaction temperature (160–260 °C) and reaction times (20–100 min). Observations showed that the bio-oil yield percentage increased from 27.3% at 160 °C to 41.9% at 260 °C, whereas bio-char yield percentage decreased from 65.2% at 160 °C to 43.2% at 260 °C. Similarly, higher reaction time also produces higher yield bio-oil percentage and lower bio-char yield percentage. The characterization results showed that the combustion properties of bio-char and bio-oil were improved after hydrothermal liquefaction due to decrease in percentage of oxygen of bio-oil and bio-char and an increase in percentage of carbon content. The carbon percentage increased from 42.73% for OPF to 59.42% and 60.47% for bio-char and bio-oil, respectively. Whereas, the percentage of oxygen decreased from 52.51 for OPF to 36.30% and 35.61 for bio-char and bio-oil. The main chemical compounds identified in bio-oil by GC-MS were phenolic compounds and their derivatives, alcohols, ketones, and esters.

Posttraumatic Stress Disorder is associated with altered reward mechanisms during the anticipation and the outcome of monetary incentive cues.

Recent studies suggest that Posttraumatic Stress Disorder (PTSD) might be associated with dysfunctional reward circuitry. However, further research is needed to understand the key role of the reward system in PTSD symptomatology. Twenty participants with PTSD and 21 Trauma-Exposed matched Controls (TECs) completed the Monetary Incentive Delay (MID) task during an MRI session. Reaction times (RTs) and hit rates were recorded. Brain activity was investigated during the anticipation and the outcome of monetary gains and losses. During the anticipation of monetary loss, PTSD participants had higher RTs than TECs. However, the groups did not differ at the neurofunctional level. During successful avoidance of monetary loss, PTSD patients showed higher activation than TECs in the left caudate nucleus. During the anticipation of monetary gains, no differences in RTs were found between groups. PTSD patients had specific activations in the right amygdala, nucleus accumbens, putamen, and middle frontal gyrus (p<0.05 family-wise error (FWE)-corrected), while TECs had specific activation in the anterior cingulate cortex. When obtaining monetary gains, PTSD patients had specific activation in the caudate nucleus, while TECs had specific activations in the right hypothalamus, subthalamic nucleus, and left inferior frontal gyrus. For the first time, functional brain activation during both the anticipation and the outcome of monetary rewards is reported altered in PTSD patients. These alterations might be associated with the complex symptomatology of PTSD.

Volt / VAR Regulation in Energy Transmission Systems Using SVC and STATCOM Devices

To ensure energy continuity in the interconnected power systems, production and consumption amounts should be in balance, and that can be possible by providing constant voltage and frequency. Otherwise, undesirable large dynamic oscillations, voltage collapse may occur, and the quality of the electrical energy deteriorates. In this study, the power system of the Denizli Region in the Western Mediterranean Region is modeled using realistic national data. The simulation study is carried out to obtain the voltages, active and reactive powers of buses in the case of no-fault and fault occurrence. Using FACTS (Flexible Alternating Current Transmission Systems) technology such as SVC and STATCOM, the power systems can be controlled, and the carrying capacities can be improved within specified limits. Facts devices are capable of producing and consuming reactive power depending on immediate needs, safe and operating flexibility, and having a high reaction time in the simulation studies. The maximum load limits are increased, and the control of the power system is facilitated. STATCOM provides 31.09 % more achievement with respect to SVC device at energy production and consumption rates for the modeled pilot region. The reliability of the power system has been increased against a voltage collapse, thanks to the SVC and STATCOM controllers. Furthermore, the voltage stability of the generator is also raised, and correspondingly the capacity of the power system enhances. The results are compared to the existing system, and the obtained improvements may be assessed for the enhancement of the interconnected network grid of Turkey.

Copper complex of polyglycerol anchored to graphene oxide as a recyclable nanocatalyst for sonochemical green synthesis of naphthoquinones

In the present study, Cu(II) immobilized on hyperbranched polyglycerol functionalized graphene oxide catalyst was prepared as a novel, green, highly efficient, and reusable heterogeneous catalyst. Then, the synthesis of naphthoquinone derivatives was performed using Go-HPG-IA-Cu(II) as a catalyst under ultrasound irradiation to afford the desired products in high yields and short reaction times. This catalyst was easily recovered and reused several times without significant loss of catalytic activity.

Pd Nanoparticle Fabricated Tetrahydroharman‐3‐carboxylic Acid Analog Immobilized CoFe2O4 Catalyzed Fast and Expedient C–C Cross and C–S Coupling

AbstractA novel Pd nanoparticles anchored tryptophan analog ligand immobilized magnetic CoFe2O4 nanocomposite material has been synthesized by post‐functionalization approach. The material has been thoroughly characterized using several advanced analytical techniques. Thereafter, the catalytic application was carried out in the C−C bond formation reactions via Suzuki and Stille cross coupling. Biphenyl derivatives were prepared in both the reactions with high efficiency and short reaction time. The exploration was further continued in the synthesis of aromatic thioethers by C−S coupling using molecular sulfur and haloarenes. The clean ligand‐free protocol, devoid of hazardous chemicals, excellent yields in short reaction time and the reusability of catalyst for several times are the key factors in the methodology.

Neural Interactions in a Spatially-Distributed Cortical Network During Perceptual Decision-Making.

Behavioral experiments evidence that attention is not maintained at a constant level, but fluctuates with time. Recent studies associate such fluctuations with dynamics of attention-related cortical networks, however the exact mechanism remains unclear. To address this issue, we consider functional neuronal interactions during the accomplishment of a reaction time (RT) task which requires sustained attention. The participants are subjected to a binary classification of a large number of presented ambiguous visual stimuli with different degrees of ambiguity. Generally, high ambiguity causes high RT and vice versa. However, we demonstrate that RT fluctuates even when the stimulus ambiguity remains unchanged. The analysis of neuronal activity reveals that the subject's behavioral response is preceded by the formation of a distributed functional network in the β-frequency band. This network is characterized by high connectivity in the frontal cortex and supposed to subserve a decision-making process. We show that neither the network structure nor the duration of its formation depend on RT and stimulus ambiguity. In turn, RT is related to the moment of time when the β-band functional network emerges. We hypothesize that RT is affected by the processes preceding the decision-making stage, e.g., encoding visual sensory information and extracting decision-relevant features from raw sensory information.

Origin of the Difference in Reactivity between Ir Catalysts for the Borylation of C-H Bonds.

A mechanistic study on the origin of the difference in reactivity between Ir catalysts for C-H borylation reactions is reported. Catalytic reactions of B2pin2 with a series of substrates that require high temperatures and long reaction times were conducted. These reactions catalyzed by the combination of [Ir(COD)(OMe)]2 and 3,4,7,8-tetramethylphenanthroline (tmphen) occur in yields that are substantially higher than those of reactions catalyzed by [Ir(COD)(OMe)]2 and 4,4'-di-tert-butylbipyridine (dtbpy). The electronic properties of Ir catalysts ligated by dtbpy or tmphen and their stoichiometric reactivity were investigated. It was found that a longer lifetime rather than higher reactivity of the catalyst leads to higher yields of reactions catalyzed by Ir-tmphen. The catalyst ligated by dtbpy decomposes principally by dissociation of the ligand and rapid borylation at the positions alpha to nitrogen. Thus, the greater stability of the catalyst containing tmphen results from its greater binding constant.

Preparation of highly dispersive solid microspherical α-Al2O3 powder with a hydrophobic surface for stereolithography-based 3D printing technology

The present research demonstrates the feasibility of the preparation of a highly dispersive, solid microspherical α-Al2O3 powder with a hydrophobic surface using a simple, rapid, and low-cost method for stereolithography-based 3D printing technology, including the synthesis of a precursor based on the in situ hydrothermal reaction of aluminum sulfate and urea, heat treatment, and surface modification using sodium oleate. The dependence of the morphologies of the precursors and α-Al2O3 powders on the type of aluminum salt, reaction time, and temperature was studied. The formation conditions of the solid spherical structure were explored. The results indicate that the formation of a solid spherical structure strongly depends on the type of aluminum salt, reaction time, and temperature. A spherical structure is only obtained by mixing aluminum sulfate with urea. Very high reaction times and temperatures facilitate the transformation of the microstructure from a solid sphere to a hollow sphere. The optimum hydrothermal reaction conditions are as follows: aluminum sulfate concentration of 0.05 mol/L, urea concentration of 0.2 mol/L, reaction temperature of 120 °C, and reaction time of 2 h. The optimum surface modification is obtained by using 3 wt% of sodium oleate, which can be used for the preparation of a 50 vol% α-Al2O3 ceramic UV-curable suspension with a viscosity of 1.66 Pa s at 30 s-1. An alumina part with a sintering density of 95.5% was fabricated using stereolithography-based 3D printing technology. The analysis of the formation mechanism of the solid spherical structure indicates that the high decomposition temperature of urea, homogeneous dissolution of urea in aluminium sulfate solution, slow OH- release by urea in the hydrothermal system, and strong coordination ability of SO42− effectively restrain the hydrolysis of Al3+ and facilitate the formation of the solid spherical precursor Al4(OH)10SO4. The solid microspherical α-Al2O3 powder is prepared by heat treatment of the precursor.

High Performance Size Exclusion Chromatography-Inductively Coupled Plasma-Mass Spectrometry to Study the Copper and Cadmium Complexation with Humic Acids.

Dissolved organic matter (DOM) plays an important role in the environment by influencing the transport and distribution of organic and inorganic components through different processes: the retention, mobilization, and bio-availability of potentially toxic elements (PTEs). The aim of the present study is to examine the dimensional characterization of humic acids (HA) extracted from soil matrix, as well as to analyze the metal distribution among different ligand classes. The molecular size distribution of the HA extract from soil showed three dimensional classes: 52 KDa, 4.5 KDa, and 900 Da. HPSEC-ICP-MS measurements demonstrated that the dimensional classes, relative to first two fractions, bind the largest part of metals. The complexing capacity of HA was evaluated to assess the pollutants mobility in the environmental system. In particular, cadmium (Cd) and copper (Cu) complexation was investigated due to the great concern regarding their bio-availability and toxicity in natural waters. The complexing capacity of HA solution (20 mg/L) was measured by titration using a high-performance size exclusion chromatography (HP-SEC) coupled to an inductively coupled mass spectrometry (ICP-MS). Results obtained by this technique are compared with those obtained by anodic stripping voltammetry (ASV) to investigate the effects of kinetic lability of complexes on measurements carried by HPSEC-ICP-MS. In this study, results of ligand concentrations and stability constants obtained via the two techniques are assessed considering the detection window associated to the applied analytical methodology. Results obtained using the two analytical techniques showed that Cd is complexed by two classes of ligands. However, the ligand concentration values obtained using the two techniques are different, because the detection window associated to the two methodologies; the complexing capacity, which was obtained as sum of the two classes of ligands, were 33 nmol/L and 9 nmol/L for ASV and HPSEC-ICP-MS, respectively. The copper complexing capacities determined by the two methodologies are comparable: 166 and 139 nmol/L for ASV and HPSEC-ICP-MS, respectively. However, the results of Cu titration differ for the two techniques, highlighting only one class of ligands when ASV was used, and two classes when HPSEC-ICP-MS was employed. Differences on results obtained by the two techniques are explained considering the kinetic lability of complexes; the results show that, differently from previous studies, also Cu complexes can be kinetically labile, if one technique with high reaction time is used, as well some cadmium complexes are sufficient stable to be determined by HPSEC-ICP-MS.

Synthesis and characterization of self-activated Ba2V2O7 nanophosphor: a potential material for W-LED applications

Barium Vanadate (Ba2V2O7) nanophosphors have been synthesized with different reaction time by hydrothermal method. The phase purity, crystal structure, crystallite size and vibrational modes of the phosphors were investigated. The Powder X-Ray Diffraction (PXRD) patterns recorded at different reaction time have exhibited an enhanced crystallinity, absence of impurities and changes in the crystalline size. The irradiation of the phosphor under UV-365 nm exhibited a white color. Photoluminescence emission peak has depicted the broad band emission ranging from 400 nm to 650 nm, which was due to the charge transfer in [VO4]3− group. The optical band gap was gradually decreased as crystalline nature increased for the as-prepared samples. The high growth oriented single phase as-prepared nanophosphor at a high reaction time have much enhanced luminescence intensity. The chromaticity coordinates plot on the Commission International de l′Eclairage (CIE) diagram has showed white color. Ultimately, the above results were suggested that, nanophosphor prepared at high duration is potentially applicable for UV chip excited white LEDs application.

Visual Reaction Time in People with and without Diabetes - A Comparative Study

Peripheral neuropathy is a common complication of type 2 diabetes in patients with poor diabetic control where reaction time increases in comparison to normal individual. Early detection of neural dysfunction denoted by increased reaction time will be helpful for the patient, to control blood sugar in order to avoid diabetic complications. This study was conducted to find out the neural deficit in diabetes by comparing the visual reaction time using ruler drop method between non-diabetics and diabetics and assessing the relationship of reaction time with increase in glycated hemoglobin (HbA1C) titre. It was a case control study among 38 diabetics and 31 healthy volunteers. Among the volunteers of age groups 20-39 years and 40-59 years, all patients with poor diabetic control showed significantly high reaction time in comparison to their non-diabetic counterparts (180.66 ms vs 231.11ms; 197.27ms vs 224.44 ms respectively). In age groups of 60-79 years, reaction time was also more in patients with high HbA1C in comparison to their non-diabetic counterparts (224.00 ms vs 230.90 ms). In comparison to non-diabetics, diabetics with increased HbA1C (7- 9%, 9-11%, 11-13%, &gt;13%) all showed significantly higher reaction time (193.54 ms vs 219.00 ms; 193.54 ms vs 225.83 ms; 193.54 ms vs 236.66 ms and 193.54 ms vs more than 250 ms respectively). A positive Pearson Correlation (r = 0.4) was also noted between HbA1C (%) and reaction time (ms) amongst the patients with poor diabetic control. Damage of vasa nervosum and formation and accumulation of sorbitol and fructose in Schwann cells might disrupt structure and function of peripheral nerves leading to neuropathy and altered visual reaction time in diabetics.

Facile Sol-Gel Synthesis of Co3O4 Nanoparticles — An Efficient and Recyclable Catalyst for the Synthesis of 1,2-Disubstituted Benzimidazoles Under Solvent-Free Conditions

High-surface-area Co3O4 nanoparticles have been prepared as a potential heterogeneous catalyst by the sol-gel method using starch as an inexpensive and a nontoxic starting material. Evidence showing that the cobalt precursor had been completely coverted into a pure crystalline Co3O4 phase with a cubic structure was obtained by X-ray diffraction analysis. The average particle size was estimated at 24 nm. The prepared catalyst was used in the synthesis of benzimidazoles. The developed methodology offers the advanvages of high yields (70–95%) and short reaction times (35–95 min) and avoids the use of toxic organic solvents. All of the reactions were carried out in the presence of Co3O4 nanoparticles (0.01 g) at 80°C under solvent-free conditions. The catalyst could be recovered and reused without any significant loss of activity.

Magnetic BaFe12O19/Al2O3: An Efficient Heterogeneous Lewis Acid Catalyst for the Synthesis of α-Aminophosphonates (Kabachnik–Fields Reaction)

The design and application of environmentally friendly catalysts to reduce the quantity of toxic wastes is critical for improving the chemical synthesis process. Therefore, BaFe12O19/Al2O3, a magnetic mesoporous nanocomposites, were designed synthesized and characterized using different techniques such as energy dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), Brunauer–Emmett–Teller (BET) adsorption method, and vibrating sample magnetometry (VSM). The prepared BaFe12O19/Al2O3 display a high surface area (1773.22 m2/g) with an average pore diameter of 3.946 nm from nitrogen sorption analysis. In addition, the synthesized nanocomposites prove to be an active heterogeneous Lewis acid catalyst for the solvent free synthesis of α-aminophosphonates at ambient temperature, through three-component reaction of aldehydes/ketones, amines and triethyl phosphite. The use of this catalyst results in an effortless magnetic recoverability and recyclability, high yield and short reaction time under solvent-free conditions.

Novel Synthesis Without Separation and Purification Processes of Carbon Dots and Silver/Carbon Hybrid Nanoparticles

This paper presents two bottom-up methods for the green synthesis of spherical carbon dots (Cdots) and silver/Cdots (Ag@Cdots) nanoparticles at alkaline medium. Both syntheses are carried out without separation and purification steps with a microwave exposure time between 30 and 60 s. In both case a natural product as glucose was used as precursor and capping agent. The obtained Cdots and Ag@Cdots hybrid are spherical in shape and monodisperse, with average particle size of lower than 10 nm and 13 nm respectively. In comparison with the methods previously reported, which need high energy consumption and/or long reaction time. The proposed methodologies are simple, low cost, environment-friendly and in accordance with green chemistry research. The morphology, composition and structure of the obtained nanoparticles were characterized by Zeta Potential and hydrodynamic size measurements, transmission electron microscopy (TEM), X-ray diffraction (XRD), ATR-FTIR spectrophotometry and thermogavimetric analysis (TGA). The synthesized nanoparticles were applied to sense tetracycline residues taking into account their fluorescent properties.

TiO2–SiO2 nanocomposite as a highly efficient catalyst for the solvent-free cyclocondensation reaction of isatins, cyclohexanones, and urea

Abstract A TiO2–SiO2 nanocomposite catalyzes the one-pot cyclocondensation reaction of 1H-indole-2,3-diones (isatins), 1,3-cyclohexanediones, and urea at T = 70°C under solvent-free conditions with high efficiency. The present method affords the corresponding spiro products in high yields and short reaction time. The unique features of the TiO2–SiO2 nanocomposite are high catalytic activity, ease of preparation, non-toxicity, low loading, and recyclability.

A Rapid and Highly Effectual Protocol for the Synthesis of Bis-coumarins using Triethylaminium-N-sulfonic Acid Tetrachloroaluminate under Solvent-Free Conditions

In this work, a rapid and highly effectual protocol for the synthesis of bis-coumarins has been developed. The one-pot quasi three-component reaction of aromatic aldehydes (1 eq.) with 4-hydroxycoumarin (2 eq.) in the presence of catalytic amount of protic acidic ionic liquid triethylaminium-N-sulfonic acid tetrachloroaluminate (TSAT) under solvent-free conditions afforded the mentioned compounds in high yields and short reaction times.

Role of Co-Solvent in the Super Critical Esterification process of Bio-Diesel Production through Karanja oil

Biofuel is necessity for the today’s era for developing country like India to fulfil its growing energy demand and concern towards the environment pollution. Bio fuel production involve following major steps such as preparation of feed stock, selection of conversion technology and the up-gradation techniques. Conventional method of bio diesel production is of time consuming and sensitive to the feed stock quality. And due to these limitations in conventional esterification processes, Supercritical Esterification has now become one of the most attractive conversion technologies for bio diesel production due to its flexibility towards the feed stock quality, high conversion rate and fast reaction time. Although, it is costlier process as compare to the conventional processes because of its extreme condition of pressure and temperature requirement. So in the present study, the Super Critical Trans-esterification of Karanja (Pongamia Pinnata) oil with Methanol is investigated. And the effect of co-solvent on the reaction condition is studied. It has been observed from the results that use of co-solvent could be a potential means to reduce the critical condition required in the Super Critical Esterification process for the bio diesel production.

Fast sulfurization of nickel foam-supported nickel-cobalt carbonate hydroxide nanowire array at room temperature for hydrogen evolution electrocatalysis

Transition metal sulfide is considered as a kind of promising noble metal-free material for hydrogen evolution reaction (HER). However, most of conventional sulfurization methods require high temperature and/or long reaction time. Herein, a sulfurization strategy at room temperature (25 °C) by using Na2S in aqueous solution is applied to sulfurize nickel foam-supported nickel-cobalt carbonate hydroxide nanowire array, during which amorphous sulfide gradually forms on the surface of nanowire and finally replaces the nanowire completely. It is found that the electrode sulfurized for 5 min in which only a thin sulfide layer is formed presents nearly identical catalytic performance for HER with the electrode that is sufficiently sulfurized for 120 min. The electrode sulfurized at 25 °C for 5 min only needs an overpotential of 100 mV to achieve hydrogen evolution current at 10 mA cm−2 in 1 M KOH, and negligible loss of activity is observed after working at a current density of 20 mA cm−2 for 25 h. The interface between carbonate hydroxide and sulfide is considered to play an important role in the catalysis of HER. The observation in this work can provide new insights into the sulfurization process and the role of sulfide in the process of HER.