scholarly journals Ag nanoparticles immobilized on new magnetic alginate halloysite as a recoverable catalyst for reduction of nitroaromatics in aqueous media

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Pourya Mohammadi ◽  
Majid Heravi ◽  
Mansoureh Daraie
Keyword(s):  
Ag Nanoparticles ◽  
Aqueous Media ◽  
Catalytic Efficiency ◽  
Catalytic Performance ◽  
Pharmaceutical Products ◽  
Biologically Active ◽  
Detection Methods ◽  
Active Materials ◽  
Recoverable Catalyst ◽  
Selection Of

AbstractAmines can be applied in the synthesis of various important compounds such as dyes, drugs, polymers, pharmaceutical products, and biologically active materials. The significant subject in the preparation of amines is the selection of the most effective heterogeneous catalyst to get the best catalytic efficiency, stability, recoverability, and reusability. For this target, we prepared new alginate magnetically recoverable nanocatalyst by stabilization of Ag nanoparticles on the surface of the halloysite (HS) [HS-Alginate-Ag/Fe3O4]. Several detection methods confirmed the production of HS-Alginate-Ag/Fe3O4 nanocatalyst and the results obtained were well explained in the context. HS-Alginate-Ag/Fe3O4 presented good catalytic performance for the hydrogenation of nitro compounds using NaBH4 as the reducing agent and hydrogen donor. The good activity and durability of this catalyst can be attributed to the good dispersion and nano-sized particle of silver nanoparticles.

scholarly journals Ag2O–MnO2/Graphene Oxide Nanocomposite

2020 ◽  
Author(s):  
Farooq Syed ◽  
Mujeeb Khan ◽  
Mohammed Rafi Shaik ◽  
Mufsir Kuniyil ◽  
M Rafiq Siddiqui ◽  
...  
Keyword(s):  
Catalytic Properties ◽  
Specific Activity ◽  
Catalytic Efficiency ◽  
Cost Effective ◽  
Catalytic Performance ◽  
Industrial Applications ◽  
Recoverable Catalyst ◽  
Aerial Oxidation ◽  
Milling Method ◽  
State Mixing

In this study, we reported the eco-friendly fabrication of Ag2O–MnO2/GRO nanocomposites by the solid-state mixing of separately prepared GRO and Ag2O–MnO2 NPs using ball milling method, a mechanochemical approach. The prepared material was studied for the catalytic effect of GRO in the system for the aerial oxidation of a variety of alcohols. It was found that the (1%)Ag2O–MnO2/(5 wt.%)GRO nanocatalyst demonstrated a high conversion ability (~100%) and excellent selectivity in the presence of O2 as a clean oxidant. The higher catalytic properties of the nanocomposite were attributed to the presence of GRO, which exhibited extraordinary catalytic properties like improved surface area, excellent chemical compatibility, and stability, as well as the introduction of several defects in the obtained nanocomposite that enhance the catalytic performance. The specific activity of 13.3 mmol·g−1·h−1 is obtained for the catalyst i.e. (1%)Ag2O–MnO2/(5 wt.%)GRO, which is reportedly superior to the various other catalysts previously reported in the literature for the same conversion reaction. Our catalytic strategy was highly selective, producing only desired products with no over-oxygenation to carboxylic acids. The merits of our catalytic methodology were: (a) facile process, (b) inexpensive and clean oxidant, (c) no surfactants or nitrogenous bases were required, (d) mild catalytic conditions, (e) cost-effective recoverable catalyst, (f) complete convertibility, (g) full selectivity, (h) rapid process, and (i) applicable to virtually all types of alcohols. So, these highlights made this catalytic strategy to be highly applicable in the industrial applications for manufacturing of carbonyls. To the best of our knowledge, this was the first study of utilizing Ag2O–MnO2/GRO composite as a catalyst for the oxidation of alcohols, highlighting the catalytic efficiency of GRO.

scholarly journals Fe3O4@SiO2-L-Cu(II): An efficient and easily recoverable catalyst for reducing/degrading environmental pollutants in aqueous medium

2021 ◽  
Author(s):  
Jaber Dadashi ◽  
Mohammad Khaleghian ◽  
Babak Mir Tamizdoust
Keyword(s):  
High Efficiency ◽  
Fourier Transforms ◽  
Organic Dyes ◽  
Aqueous Media ◽  
Environmental Pollutants ◽  
Catalytic Efficiency ◽  
Significant Loss ◽  
Homogeneous Catalyst ◽  
X Ray ◽  
Recoverable Catalyst

Abstract In the present study, a magnetically recoverable catalyst is synthesized through immobilizing copper (II) over the Fe3O4@SiO2 nanoparticles (NPs) surface [Fe3O4@SiO2-L-Cu (II)] (L = pyridine-4-carbaldehyde thiosemicarbazide). Accordingly, synthesized catalysts were determined and characterized by energy dispersive X-ray spectrometry (EDS), Fourier transforms infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), vibrating sample magnetometer (VSM), and thermogravimetric-differential thermal analysis (TG-DTA) procedures. Using [Fe3O4@SiO2-L-Cu (II)], 4-Nitrophenol (4-NP), Cr(VI), and organic dyes, e.g., Methylene blue (MB) and Congo Red (CR) were reduced in aqueous media. As shown by results of Catalytic performance investigations, [Fe3O4@SiO2-L-Cu (II)] performance was outstanding concerning reduction reactions in mild conditions. Remarkable attributes of this method are high efficiency, removal of a homogeneous catalyst, easy recovery from the reaction mix, and uncomplicated route. The amount of activity in this catalytic system was almost constant after several stages of recovery and reuse. The results show that the catalyst was efficient and easily recoverable in the successive run without a significant loss of catalytic efficiency.

scholarly journals Ag nanoparticles immobilized on new mesoporous triazine-based carbon (MTC) as green and recoverable catalyst for reduction of nitroaromatic in aqueous media

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Narges Vahedi-Notash ◽  
Majid M. Heravi ◽  
Ali Alhampour ◽  
Pourya Mohammadi
Keyword(s):  
Electron Microscopy ◽  
Inductively Coupled Plasma ◽  
Aqueous Media ◽  
Catalytic Efficiency ◽  
Active Species ◽  
X Ray Diffraction ◽  
X Ray ◽  
Inductively Coupled ◽  
Transmission Electron ◽  
Recoverable Catalyst

Abstract In this research, we reported an effective method for the synthesis of a new mesoporous triazine-based carbon (MTC) substrate and its application as the green and recoverable catalyst in the synthesis of organic compounds. The porous carbon acted as a substrate for silver active species after its surface modification by chloroacetonitrile (Ag@MTC). The Ag@MTC nanocatalyst was characterized by several techniques namely, Fourier-transform infrared spectroscopy, field emission scanning electron microscopy with energy dispersive spectroscopy, X-ray diffraction, transmission electron microscopy, Brunauer–Emmett–Teller surface area analysis, and inductively coupled plasma. The Ag@MTC catalyst was applied for the reduction of nitroaromatic compounds in aqueous media by using NaBH4 (reducing agent) at room temperature. This nanocatalyst can be readily recovered and recycled for at least nine runs without a notable decrease in its efficiency. Catalytic efficiency studies exhibited that Ag@MTC nanocatalyst had good activity towards reduction reactions.

Catalytic Performance of Imidazolide Basic Ionic Liquid in Knoevenagel Reactions in Aqueous Media

2011 ◽  
Vol 32 (4) ◽  
pp. 693-698
Author(s):  
Xuewei CHEN ◽  
Hongbing SONG ◽  
Xuehui LI ◽  
Furong WANG ◽  
Yu QIAN
Keyword(s):  
Ionic Liquid ◽  
Aqueous Media ◽  
Catalytic Performance ◽  
Basic Ionic Liquid

scholarly journals Clinical Pharmacology of Antibody-Drug Conjugates

Antibodies ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 20
Author(s):  
Iftekhar Mahmood
Keyword(s):  
Clinical Pharmacology ◽  
Patient Population ◽  
Inflammatory Diseases ◽  
Biologically Active ◽  
Myelogenous Leukemia ◽  
Optimum Dose ◽  
Antibody Drug Conjugates ◽  
Drug Conjugates ◽  
Selection Of ◽  
Antibody Drug

Antibody-drug conjugates (ADCs) are biopharmaceutical products where a monoclonal antibody is linked to a biologically active drug (a small molecule) forming a conjugate. Since the approval of first ADC (Gemtuzumab ozogamicin (trade name: Mylotarg)) for the treatment of CD33-positive acute myelogenous leukemia, several ADCs have been developed for the treatment of cancer. The goal of an ADC as a cancer agent is to release the cytotoxic drug to kill the tumor cells without harming the normal or healthy cells. With time, it is being realized that ADCS can also be used to manage or cure other diseases such as inflammatory diseases, atherosclerosis, and bacteremia and some research in this direction is ongoing. The focus of this review is on the clinical pharmacology aspects of ADC development. From the selection of an appropriate antibody to the finished product, the entire process of the development of an ADC is a difficult and challenging task. Clinical pharmacology is one of the most important tools of drug development since this tool helps in finding the optimum dose of a product, thus preserving the safety and efficacy of the product in a patient population. Unlike other small or large molecules where only one moiety and/or metabolite(s) is generally measured for the pharmacokinetic profiling, there are several moieties that need to be measured for characterizing the PK profiles of an ADC. Therefore, knowledge and understanding of clinical pharmacology of ADCs is vital for the selection of a safe and efficacious dose in a patient population.

scholarly journals Improved Antioxidant Capacity of Black Tea Waste Utilizing PlantCrystals

Molecules ◽  
2021 ◽  
Vol 26 (3) ◽  
pp. 592 ◽  
Author(s):  
Abraham M. Abraham ◽  
Reem M. Alnemari ◽  
Jana Brüßler ◽  
Cornelia M. Keck
Keyword(s):  
Antioxidant Capacity ◽  
Aqueous Media ◽  
Natural Antioxidants ◽  
Black Tea ◽  
Pharmaceutical Products ◽  
Small Scale ◽  
Alternative Source ◽  
Significant Difference ◽  
Plant Waste

Antioxidants are recommended to prevent and treat oxidative stress diseases. Plants are a balanced source of natural antioxidants, but the poor solubility of plant active molecules in aqueous media can be a problem for the formulation of pharmaceutical products. The potential of PlantCrystal technology is known to improve the extraction efficacy and antioxidant capacity (AOC) of different plants. However, it is not yet proved for plant waste. Black tea (BT) infusion is consumed worldwide and thus a huge amount of waste occurs as a result. Therefore, BT waste was recycled into PlantCrystals using small-scale bead milling. Their characteristics were compared with the bulk-materials and tea infusion, including particle size and antioxidant capacity (AOC) in-vitro. Waste PlantCrystals possessed a size of about 280 nm. Their AOC increased with decreasing size according to the DPPH (1,1-diphenyl-2-picrylhydrazyl) and ORAC (oxygen radical absorbance capacity) assays. The AOC of the waste increased about nine-fold upon nanonization, leading to a significantly higher AOC than the bulk-waste and showed no significant difference to the infusion and the used standard according to DPPH assay. Based on the results, it is confirmed that the PlantCrystal technology represents a natural, cost-effective plant-waste recycling method and presents an alternative source of antioxidant phenolic compounds.

scholarly journals A Students’ Preferences-Based Approach to Select Methods for Detecting and Handling Free-Riding

2021 ◽  
pp. 027347532199210
Author(s):  
Else-Marie van den Herik ◽  
Tim M. Benning
Keyword(s):  
International Students ◽  
Evaluation System ◽  
Online Survey ◽  
Free Riding ◽  
Detection Methods ◽  
Chi Squared ◽  
Ranking Task ◽  
Handling Methods ◽  
Selection Of ◽  
Marketing Educators

Free-riding is a serious challenge in group projects. While there are various methods to reduce free-riding, marketing educators still face a difficult task when selecting an appropriate method for their course. In this study, we propose a students’ preferences-based approach that supports marketing educators with the selection of methods to detect and handle free-riding. To measure these preferences, students completed an online survey based on a choice task about two methods to detect free-riding and a ranking task about four methods to handle free-riding ( n = 254). Their answers were analyzed using chi-squared tests, Borda scores, and rank-ordered logit models. The results show that (a) neither Dutch nor international students have a clear preference for one of the two detection methods (the reporting system vs. the process evaluation system), (b) grade discussion (a possible reduction of the free-rider’s grade based on a conversation with the course coordinator about each student’s contribution) is the most preferred method to handle free-riding, and (c) international students have a stronger preference for stricter handling methods. Marketing educators can apply the proposed approach, or use our specific findings, for designing methods to reduce free-riding in their courses.

Localization of Chromogranins, Non-neuron-specific Enolase, and Different Forms of Somatostatins in the Submandibular Salivary Glands of Mice

1990 ◽  
Vol 69 (8) ◽  
pp. 1494-1499 ◽  
Author(s):  
A. Letić-Gavrilović ◽  
K. Abe
Keyword(s):  
Growth Factor ◽  
Salivary Glands ◽  
Chromogranin A ◽  
Neuron Specific Enolase ◽  
Biologically Active ◽  
Detection Methods ◽  
Duct System ◽  
Male Mice ◽  
Chromogranin B ◽  
Submandibular Salivary Glands

The localizations of chromogranins A, B, and C, neuron-specific enolase (NSE, γγ-type) and non-NSE (αα-type), and different forms of somatostatins were immunocytochemically identified. The localizations were compared with those of epidermal growth factor (EGF) and nerve growth factor (NGF) in the submandibular salivary glands (SMG) of male mice at five to six weeks of age, with use of a variety of antibodies and the peroxidase-antiperoxidase (PAP) and avidin-biotin complex (ABC) detection methods. In the SMG of male mice, the major chromogranin present was chromogranin A, whereas chromogranins B and C were not detected at these ages by either method. Chromogranin Alike immunoreactivity was located in the granular convoluted tubule (GCT) cells of the SMG, whereas non-NSE immunoreactivity was observed throughout the duct system and in some acinar-associated cells. NSE was not detected in any part of the SMG. The distribution of chromogranin A and somatostatins in the GCT cells was similar to that of EGF and NGF. Our results strongly suggest that chromogranin A and somatostatins, but not chromogranin B or C, may be useful as a means of differentiation of the cells in the duct system of the SMG responsible for the production of biologically-active factors.

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