Publications by authors named "Anis Rahman"

12 Publications

  • Page 1 of 1

Hypervalent Iodine (III) Catalyzed Regio- and Diastereoselective Aminochlorination of Tailored Electron Deficient Olefins via GAP Chemistry.

Front Chem 2020 7;8:523. Epub 2020 Jul 7.

Department of Chemistry, Faculty of Chemical and Life Sciences, Abdul Wali Khan University, Mardan, Pakistan.

Herein, we report a protocol for highly efficient hypervalent iodine (III) mediated, group-assisted purification (GAP) method for the regioselectivities and stereoselective aminochlorination of electron-deficient olefins. A series of vicinal chloramines with multifunctionalities were acquired in moderate to excellent yields (45-94%), by merely mixing the GAP auxiliary-anchored substrates with dichloramine T and tosylamide as chlorine/nitrogen sources and iodobenzene diacetate as a catalyst. The vicinal chloramines were obtained without any column chromatographic purification and recrystallization simply by washing the reaction mixture with a minimum amount of common inexpensive solvents and thus avoiding wastage of silica, solvents, time, and labor. The GAP auxiliary is recyclable and reusable. This strategy is easy to handle, cost-effective, greener, sustainable, environmentally benign, and mostly suitable for the syntheses of vicinal haloamines from various electron-deficient alkenes.
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http://dx.doi.org/10.3389/fchem.2020.00523DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7358771PMC
July 2020

Rh(III)-Catalyzed [3 + 3] Annulation Reaction of Cyclopropenones and Sulfoxonium Ylides toward Trisubstituted 2-Pyrones.

J Org Chem 2020 01 6;85(2):360-366. Epub 2019 Nov 6.

School of Chemistry & Materials Science , Jiangsu Normal University , Xuzhou 221116 , P. R. China.

A new Rh(III)-catalyzed [3 + 3] annulation reaction between cyclopropenones and β-ketosulfoxonium ylides has been reported, enabling metal carbene insertion to access a wide range of trisubstituted 2-pyrones with moderate to excellent yields via C-C single-bond cleavage, in which sulfoxonium ylides serve as potential safe precursors of metal carbenes. This reaction occurred under redox-neutral conditions with a broad substrate scope.
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http://dx.doi.org/10.1021/acs.joc.9b02253DOI Listing
January 2020

Terahertz Reflectometry Imaging of Carbon Nanomaterials for Biological Application.

J Nanomed Nanotechnol 2019 26;10(4). Epub 2019 Aug 26.

Department of Natural Sciences, Center for Nanotechnology, Coppin State University, 2500 W. North Ave, Baltimore, MD, USA.

The multiwalled carbon nanotubes has a myriad of applications due to its unique electrical and mechanical properties. The biomedical application of multiwalled carbon nanotubes that have been reported include drug delivery, medical imaging, gene delivery, tissue regeneration, and diagnostics. Proper characterization is required to enhance the potential application of the multiwalled carbon nanotubes. Terahertz technology is a relatively unfamiliar spectrometric technique that show promise in efficiently characterizing multiwalled carbon nanotubes. In this paper, terahertz imaging was used to characterize multiwalled carbon nanotube in comparison with other characterization techniques, including transmission electron microscopy and field emission scanning electron microscopy. The average diameter of the carbon nanotubes from the reconstructed terahertz images was 48.54 nm, while the average length of a fiber was found to be approximately 1.2 μm. The multiwalled carbon nanotubes were additionally characterized by FTIR, Raman spectroscopy, and Energy-dispersive X-ray spectroscopy.
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http://dx.doi.org/10.35248/2157-7439.19.10.535DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6738974PMC
August 2019

Engineering dendrimers to produce dendrimer dipole excitation based terahertz radiation sources suitable for spectrometry, molecular and biomedical imaging.

Nanoscale Horiz 2017 May 20;2(3):127-134. Epub 2017 Mar 20.

Applied Research and Photonics, Harrisburg, PA 17111, USA.

Two critical nanoscale design parameters (CNDPs); namely, surface chemistry and interior compositions of poly(amidoamine) (PAMAM) dendrimers were systematically engineered to produce unique hyperpolarizable, electro-optical substrates. These electro-optically active dendritic films were demonstrated to produce high quality, continuous wave terahertz radiation when exposed to a suitable pump laser that could be used for spectrometry and molecular imaging. These dendrimer based dipole excitation (DDE) terahertz sources were used to construct a working spectrometer suitable for many practical applications including THz imaging and analysis of encapsulated hydrogen species in fullerenes.
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http://dx.doi.org/10.1039/c7nh00010cDOI Listing
May 2017

Interaction of Sensitizing Dyes with Nanostructured TiO2 Film in Dye-Sensitized Solar Cells Using Terahertz Spectroscopy.

Sci Rep 2016 07 22;6:30140. Epub 2016 Jul 22.

Center for Nanotechnology for Department of Natural Sciences, Coppin State University, 2500 W. North Avenue, Baltimore, MD 21216, USA.

The objective of this investigation was to shed light on the nature of interaction of different organic dyes and an inorganic dye, Ruthenium (II) polypyridine complex, with TiO2 nanoparticles. TiO2 is commonly deployed as an efficient energy transfer electrode in dye sensitized solar cells. The efficiency of dye sensitized solar cells is a function of the interaction of a dye with the electrode material such as TiO2. To the best of our knowledge the present study is the first effort in the determination of terahertz absorbance signals, investigation of real-time dye permeation kinetics, and the surface profiling and 3D imaging of dye sensitized TiO2 films. Herein, we report that the terahertz spectra of the natural dye sensitized TiO2 films were distinctively different from that of the inorganic dye with prominent absorption of natural dyes occurring at approximately the same wavelength. It was observed that the permeation of the natural dyes were more uniform through the layers of the mesoporous TiO2 compared to the inorganic dye. Finally, defects and flaws on TiO2 film were easily recognized via surface profiling and 3D imaging of the films. The findings thus offer a new approach in characterization of dye sensitized solar cells.
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http://dx.doi.org/10.1038/srep30140DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4957082PMC
July 2016

Early detection of skin cancer via terahertz spectral profiling and 3D imaging.

Biosens Bioelectron 2016 Aug 22;82:64-70. Epub 2016 Mar 22.

Rutgers University, 1 Worlds Fair Drive, Suite 2400, Somerset, NJ 08873, United States.

Terahertz scanning reflectometry, terahertz 3D imaging and terahertz time-domain spectroscopy have been used to identify features in human skin biopsy samples diagnosed for basal cell carcinoma (BCC) and compared with healthy skin samples. It was found from the 3D images that the healthy skin samples exhibit regular cellular pattern while the BCC skin samples indicate lack of regular cell pattern. The skin is a highly layered structure organ; this is evident from the thickness profile via a scan through the thickness of the healthy skin samples, where, the reflected intensity of the terahertz beam exhibits fluctuations originating from different skin layers. Compared to the healthy skin samples, the BCC samples' profiles exhibit significantly diminished layer definition; thus indicating a lack of cellular order. In addition, terahertz time-domain spectroscopy reveals significant and quantifiable differences between the healthy and BCC skin samples. Thus, a combination of three different terahertz techniques constitutes a conclusive route for detecting the BCC condition on a cellular level compared to the healthy skin.
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http://dx.doi.org/10.1016/j.bios.2016.03.051DOI Listing
August 2016

The subgingival microbiome of clinically healthy current and never smokers.

ISME J 2015 Jan 11;9(1):268-72. Epub 2014 Jul 11.

Division of Periodontology, College of Dentistry, The Ohio State University, Columbus, OH, USA.

Dysbiotic oral bacterial communities have a critical role in the etiology and progression of periodontal diseases. The goal of this study was to investigate the extent to which smoking increases risk for disease by influencing the composition of the subgingival microbiome in states of clinical health. Subgingival plaque samples were collected from 200 systemically and periodontally healthy smokers and nonsmokers. 16S pyrotag sequencing was preformed generating 1,623,713 classifiable sequences, which were compared with a curated version of the Greengenes database using the quantitative insights into microbial ecology pipeline. The subgingival microbial profiles of smokers and never-smokers were different at all taxonomic levels, and principal coordinate analysis revealed distinct clustering of the microbial communities based on smoking status. Smokers demonstrated a highly diverse, pathogen-rich, commensal-poor, anaerobic microbiome that is more closely aligned with a disease-associated community in clinically healthy individuals, suggesting that it creates an at-risk-for-harm environment that is primed for a future ecological catastrophe.
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http://dx.doi.org/10.1038/ismej.2014.114DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4274424PMC
January 2015

Sorption characteristics of atrazine and imazethapyr in soils of new zealand: importance of independently determined sorption data.

J Agric Food Chem 2009 Nov;57(22):10866-75

AgResearch, Ruakura Research Centre, East Street, Private Bag 3123, Hamilton, New Zealand.

We investigated sorption characteristics of two commonly used herbicides, atrazine and imazethapyr, in 101 soils with allophanic and non-allophanic clays of New Zealand using the batch equilibration technique. Soil properties, such as organic carbon (OC) content, texture, pH, amount and type of clay, and cation-exchange capacity (CEC), were tested against the sorption coefficients (Kd) of these herbicides. There was a wide variation in the sorption affinities of the soils, as the Kd values of atrazine and imazethapyr ranged from 0.7 to 52.1 and from 0.1 to 11.3 L kg(-1), respectively. For atrazine, the sorption affinities for the allophanic set of soils (mean Kd of 8.5 L kg(-1)) were greater than for the non-allophanic set of soils (mean Kd of 7.5 L kg(-1)). However, no effect of allophanic status was found for imazethapyr sorption (mean Kd of 0.82 and 0.76 L kg(-1) for allophanic and non-allophanic, respectively). None of the measured soil properties could alone explain adequately the sorption behavior of the herbicides. The variation of OC soil sorption coefficients, Koc, was also larger for atrazine (mean Koc of 126.9 L kg(-1)) than for imazethapyr (mean Koc of 13.2 L kg(-1)). The prediction equations for atrazine and imazethapyr developed overseas failed to provide the acceptable values of sorption coefficients for the soils of New Zealand. The study highlights the danger of using sorption coefficient data from the literature for practical assessments of the herbicide leaching in New Zealand soils.
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http://dx.doi.org/10.1021/jf901365jDOI Listing
November 2009

Field dissipation of acetochlor in two New Zealand soils at two application rates.

J Environ Qual 2004 May-Jun;33(3):930-8

AgResearch, Hamilton, New Zealand.

The persistence of pesticides in soils has both economic and environmental significance and is often used as a key parameter in pesticide risk assessment. Persistence of acetochlor [2'-ethyl-6'-methyl-N-(ethoxymethyl)-2-chloroacetylanilide] in two New Zealand field soils was measured over two years and the data were used to identify models that adequately describe acetochlor persistence in the field. Acetochlor was sprayed onto six fallow plots (3 x 9 m each) at each site at the recommended rate (2.5 kg a.i. ha(-1)) and at twice that rate. Acetochlor concentrations were measured in soil cores. Simple first-order kinetics (Model 1) adequately described acetochlor persistence in Hamilton clay loam soil (Humic Hapludull, Illuvial Spadic) at the high application rate, but overestimated it at the low application rate. A quadratic model (Model 2), a first-order double-exponential model (Model 3), a first-order biphasic model (Model 4), or a two-compartment model (Model 5) better described acetochlor persistence at the low application rate. The time for 50% (DT50) and 90% (DT90) of initial acetochlor loss was approximately 9 and 56 d, and 18 and 63 d at low and high application rates, respectively. The more complex Models 2 through 5 also better described the biphasic dissipation of acetochlor in Horotiu sandy loam soil (Typic Orthic Allophanic) than Model 1, with Model 1 significantly underestimating acetochlor concentrations on the day of application at both application rates. The DT50 and DT90 values were 5 and 29 d and 7 and 31 d at low and high application rates, respectively. Overall, application rate significantly affected the DT50 and DT90 values in the Hamilton soil, but not in the Horotiu soil. Faster acetochlor loss in the Horotiu soil possibly resulted from the higher soil organic carbon content that retained more acetochlor near the soil surface where higher temperature and photolysis accelerated the loss.
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http://dx.doi.org/10.2134/jeq2004.0930DOI Listing
September 2004

Prediction of field atrazine persistence in an allophanic soil with Opus2.

Pest Manag Sci 2004 May;60(5):447-58

AgResearch Limited, Ruakura Research Centre, Private Bag 3123, Hamilton, New Zealand.

A modified version of the model Opus was applied to measurements of soil water dynamics and atrazine (6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine) persistence in a Bruntwood silt loam soil (Haplic Andosol, FAO system) in Hamilton, New Zealand. The modified model, Opus2, is briefly described and parameter estimation for the simulations is discussed. Soil water dynamics were more accurately described by applying measured soil hydraulic properties than by estimating them using pedotransfer functions. A parameter sensitivity analysis revealed that degradation was the most relevant process in simulating pesticide behaviour by Opus2. The Arrhenius equation incorporated in Opus2 did not correctly describe the effect of temperature on degradation rates obtained at 10, 20 and 30 degrees C. However, as the Arrhenius coefficient is a very sensitive parameter and soil temperature variation was relatively narrow in the field, the Arrhenius coefficient was approximated from the laboratory study. The simulation results obtained were superior to modelling at constant temperature. Field measured persistence of atrazine in the topsoil was underpredicted using the half-life determined in the laboratory at 10 degrees C. Modelling with a lag phase followed by accelerated degradation by use of a sigmoidal degradation equation in Opus2 significantly improved the modelling results. Nevertheless, degradation processes in the laboratory under controlled conditions did not accurately represent field dissipation, however well the laboratory degradation data could be described by simple kinetic equations. The study indicates the importance of improving field techniques for measuring degradation, and developing laboratory protocols that yield degradation data that are more representative of pesticide dynamics in field soils.
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http://dx.doi.org/10.1002/ps.832DOI Listing
May 2004

Dissipation of the herbicide clopyralid in an allophanic soil: laboratory and field studies.

J Environ Sci Health B 2003 Nov;38(6):683-95

AgResearch, Ruakura Research Centre, Hamilton, New Zealand.

Soil dissipation of the herbicide clopyralid (3,6-dichloropicolinic acid) was measured in laboratory incubations and in field plots under different management regimes. In laboratory studies, soil was spiked with commercial grade liquid formulation of clopyralid (Versatill, 300 g a.i. L(-1) soluble concentrate) @ 0.8 microg a.i. g(-1) dry soil and the soil water content was maintained at 60% of water holding capacity of the soil. Treatments included incubation at 10 degrees C, 20 degrees C, 30 degrees C, day/night cycles (25/15 degrees C) and sterilized soil (20 degrees C). Furthermore, a field study was conducted at the Waikato Research Orchard near Hamilton, New Zealand starting in November 2000 to measure dissipation rates of clopyralid under differing agricultural situations. The management regimes were: permanent pasture, permanent pasture shielded from direct sunlight, bare ground, and bare ground shielded from direct sunlight. Clopyralid was sprayed in dilute solution @ 600 g a.i. ha(-1) on to field plots. Herbicide residue concentrations in soil samples taken at regular intervals after application were determined by gas chromatograph with electron capture detector. The laboratory experiments showed that dissipation rate of clopyralid was markedly faster in non-sterilized soil (20 degrees C), with a half-life (t1/2) of 7.3 d, than in sterilized soil (20 degrees C) with t1/2 of 57.8 d, demonstrating the importance of micro-organisms in the breakdown process. Higher temperatures led to more rapid dissipation of clopyralid (t1/2, 4.1 d at 30 degrees C vs 46.2 d at 10 degrees C). Dissipation was also faster in the day/night (25/15 degrees C) treatment (t1/2, 5.4 d), which could be partly due to activation of soil microbes by temperature fluctuations. In the field experiment, decomposition of clopyralid was much slower in the shaded plots under pasture (t1/2, 71.5 d) and bare ground (t1/2, 23.9 d) than in the unshaded pasture (t1/2, 5.0 d) and bare ground plots (t1/2, 12.9 d). These studies suggest that environmental factors such as temperature, soil water content, shading, and different management practices would have considerable influence on rate of clopyralid dissipation.
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http://dx.doi.org/10.1081/PFC-120025553DOI Listing
November 2003

Spatial variability of atrazine dissipation in an allophanic soil.

Pest Manag Sci 2003 Aug;59(8):893-903

AgResearch Limited, Ruakura Research Centre, Private Bag 3123, Hamilton, New Zealand.

The small-scale variability (0.5 m) of atrazine (6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine) concentrations and soil water contents in a volcanic silt loam soil (Haplic Andosol, FAO system) was studied in an area of 0.1 ha. Descriptive and spatial statistics were used to analyse the data. On average we recovered 102% of the applied atrazine 2 h after the herbicide application (CV = 35%). An increase in the CV of the concentrations with depth could be ascribed to a combination of extrinsic and intrinsic factors. Both variables, atrazine concentrations and soil water content, showed a high horizontal variability. The semivariograms of the atrazine concentrations exhibited the pure nugget effect, no pattern could be determined along the 15.5-m long transects on any of the seven sampling days over a 55-day period. Soil water content had a weak spatial autocorrelation with a range of 6-10 m. The dissipation of atrazine analysed using a high vertical sampling resolution of 0.02 m to 0.2 m showed that 70% of the applied atrazine persisted in the upper 0.02-m layer of the soil for 12 days. After 55 days and 410 mm of rainfall the centre of the pesticide mass was still at a soil depth of 0.021 m. The special characteristics of the soil (high organic carbon content, allophanic clay) had a strong influence on atrazine sorption and mobility. The mass recovery after 55 days was low. The laboratory degradation rate for atrazine, determined in a complementary incubation study and corrected for the actual field temperature using the Arrhenius equation, only accounted for about 35% of the losses that occurred in the field. Results suggest field degradation rates to be more changeable in time and much faster than under controlled conditions. Preferential flow is discussed as a component of the field transport process.
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http://dx.doi.org/10.1002/ps.693DOI Listing
August 2003