Publications by authors named "Asma Iqbal"

24 Publications

  • Page 1 of 1

Selective Electrosynthesis of 2,5-diformylfuran (DFF) in a Continuous Flow System.

ChemSusChem 2021 Dec 20. Epub 2021 Dec 20.

Shanghai Jiaotong University: Shanghai Jiao Tong University, School of Chemistry and Chemical Engineering, CHINA.

The gram-scale selective oxidation of biomass-based chemicals, in particular 5-hydroxymethylfurfural (HMF), into value-added 2,5-diformylfuran (DFF) has a high application potential but suffers from high cost, low selectivity and needs harsh reaction conditions. Besides, electrooxidation strategy requires the usage of expensive electrodes and struggles with low selectivity and efficiency, which restricts its further scale-up application. In this regard, we developed a continuous flow system through redox mediator I-/I2 for the efficient synthesis of DFF, which can accelerate the mass transfer of I- (I2) to aqueous (organic) phase and avoid over-oxidations to achieve high selectivity. After the solvent system, iodine concentration and reaction time were optimized, highly efficient DFF synthesis (selectivity: >99%) could be achieved in the electrochemical flow system using inexpensive graphite felt (GF) as electrodes. Moreover, selective HMF oxidation was paired with hydrogen evolution reaction (HER) with increased efficiency after using in-situ loaded GF-CoS2/CoS and GF-Pt electrodes. As a result, the required energy to achieve the gram-scale synthesis of DFF is significantly reduced, demonstrating the outstanding potential for large-scale production of the target product.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/cssc.202102596DOI Listing
December 2021

Morphology genetic 3D hierarchical SnOmicrostructures constructed by Sub 5 nm nanocrystals for highly sensitive ethanol-sensor.

Nanotechnology 2021 Sep 7;32(48). Epub 2021 Sep 7.

Shanghai Electrochemical Energy Devices Research Center, School of Chemistry and Chemical Engineering and State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai, People's Republic of China.

SnOis widely used for ethanol-sensing applications due to its excellent physicochemical properties, low toxicity and high sensitivity. However it is a challenge to construct 3D-hierarchical structures with sub 5 nm primary grain particle, which is the optimized size for ethanol sensor. Herein, genetic tri-level hierarchical SnOmicrostructures are synthesised by the genetic conversion of 3D hierarchical SnSflowers assembled by ultrathin nanosheets. The SnSnanosheets are morphology genetic converted to porous nanosheets with sub 5 nm SnOnanoparticles during the calcination process. When used for the detection of ethanol, the sensor exhibits a high sensitivity of 0.5 ppm (/ = 6.8) and excellent gas-sensing response (/= 183 to 100 ppm) with short response/recovery time (12 s/11 s). The excellent gas sensing performance is much better than that of the previous reported SnO-based sensors. The highly sensitivity is attributed to the large surface area derived from the recrystallization and volume changes, which offers more active sites during the morphology genetic conversion from SnSto SnO. Furthermore, the flower-like 3D structure enhances the stability of the materials and is beneficial for the mass diffusion dynamics of ethanol.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1088/1361-6528/ac2019DOI Listing
September 2021

Chemical Coupled PEDOT:PSS/Si Electrode: Suppressed Electrolyte Consumption Enables Long-Term Stability.

Nanomicro Lett 2021 Jan 8;13(1):54. Epub 2021 Jan 8.

School of Chemistry and Chemical Engineering and State Key Laboratory of Metal Matrix Composites, Shanghai Electrochemical Energy Devices Research Center, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China.

Huge volume changes of Si during lithiation/delithiation lead to regeneration of solid-electrolyte interphase (SEI) and consume electrolyte. In this article, γ-glycidoxypropyl trimethoxysilane (GOPS) was incorporated in Si/PEDOT:PSS electrodes to construct a flexible and conductive artificial SEI, effectively suppressing the consumption of electrolyte. The optimized electrode can maintain 1000 mAh g for nearly 800 cycles under limited electrolyte compared with 40 cycles of the electrodes without GOPS. Also, the optimized electrode exhibits excellent rate capability. The use of GOPS greatly improves the interface compatibility between Si and PEDOT:PSS. XPS Ar etching depth analysis proved that the addition of GOPS is conducive to forming a more stable SEI. A full battery assembled with NCM 523 cathode delivers a high energy density of 520 Wh kg, offering good stability.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s40820-020-00564-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8187542PMC
January 2021

Chitosan based controlled release drug delivery of mycophenolate mofetil loaded in nanocarriers system: synthesis and evaluation.

Drug Dev Ind Pharm 2021 Mar 10;47(3):477-483. Epub 2021 Mar 10.

Faculty of Pharmacy, University of Central Punjab, Lahore, Pakistan.

Organ transplantation is an important and critical procedure, which requires the suppression of immunity, and to suppress the immunity, a constant plasma concentration of immunosuppressant is required. The said objective can be achieved by formulating a controlled release drug delivery system of the drug. Chitosan (CHT) nanoparticles (NPs) have been revolutionizing the conventional drug delivery system, for the past two decades. The aim of the current research work was to develop and evaluate CHT-based mycophenolate mofetil (MMF) loaded nanoparticles (CHT/MMF-NPs) using different drug to polymer ratios. The challenge was to entrap a lipophilic drug within NPs by the ionic gelation method of the positively charged CHT, using tripolyphosphate (TPP) as the crosslinking agent. The prepared CHT/MMF-NPs were evaluated for physical and chemical characterizations, including particle size, surface charge, entrapment efficiency (EE), surface morphology by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) for chemical compatibilities, X-ray diffractometry (XRD) and dissolution studies. Outcomes of the studies revealed that particles were 260 ± 17 nm in diameter, with the smooth and regular surface. Satisfactory values of EE (99%) have indicated the suitability of selected ingredients and employed methodology. Moreover, FTIR has confirmed the chemical compatibilities of the formulations. dissolution studies have indicated diffusion type of controlled and sustained drug release during 24 h, with zero-order, as best fit kinetic model. Conclusively, the successful achievement of objectives has indicated the suitability of excipients and methodology to prepare CHT/MMF-NPs for better therapeutic outcomes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1080/03639045.2021.1892739DOI Listing
March 2021

A review of Cryptosporidium spp. and their detection in water.

Water Sci Technol 2021 Jan;83(1):1-25

C.R.E.M. Co Labs, Units 1-2, 3403 American Drive, Mississauga, ON, Canada, L4V 1T4.

Cryptosporidium spp. are one of the most important waterborne pathogens worldwide and a leading cause of mortality from waterborne gastrointestinal diseases. Detection of Cryptosporidium spp. in water can be very challenging due to their low numbers and the complexity of the water matrix. This review describes the biology of Cryptosporidium spp. and current methods used in their detection with a focus on C. parvum and C. hominis. Among the methods discussed and compared are microscopy, immunology-based methods using monoclonal antibodies, molecular methods including PCR (polymerase chain reaction)-based assays, and emerging aptamer-based methods. These methods have different capabilities and limitations, but one common challenge is the need for better sensitivity and specificity, particularly in the presence of contaminants. The application of DNA aptamers in the detection of Cryptosporidium spp. oocysts shows promise in overcoming these challenges, and there will likely be significant developments in aptamer-based sensors in the near future.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2166/wst.2020.515DOI Listing
January 2021

Self-Supported NaTi(PO) Nanorod Arrays: Balancing Na and Electron Kinetics via Optimized Carbon Coating for High-Power Sodium-Ion Capacitor.

ACS Appl Mater Interfaces 2020 Nov 27;12(45):50388-50396. Epub 2020 Oct 27.

Shanghai Electrochemical Energy Devices Research Center, School of Chemistry and Chemical Engineering and State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, P. R. China.

The NaTi(PO) (NTP) anode materials exhibit high Na diffusion dynamics; carbon-based materials can effectively improve its limited electronic conductivity. However, the low Na diffusion of NTP/C composite materials from inhomogeneous carbon mixing or uncontrollable carbon coating cannot keep up with fast electron transfer, leading to undesirable electrochemical performances. Herein, a uniform and controllable carbon layer is designed on the self-supported-coated NTP nanorod arrays with binder-free ([email protected] NR) to improve Na and electron kinetics simultaneously. As a result, the [email protected] NR electrodes possess initial coulombic efficiency (ICE = 97%), good rate capabilities (89.1 mA h g at 100 C), and stability with ≈78.4% of capacity retention rate at even 30 C over 1200 cycles. The sodium-ion capacitors with [email protected] NR as an anode and commercially activated carbon as a cathode exhibit ∼9180.0 W kg of power density at 10 A g and super high retention of ≈94.5% at 1 A g over 7000 cycles. This work will help balance transport kinetics between the ion and electron for materials applied in storage devices.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsami.0c13766DOI Listing
November 2020

Solid Lipid Nanoparticles of Mycophenolate Mofetil: An Attempt to Control the Release of an Immunosuppressant.

Int J Nanomedicine 2020 5;15:5603-5612. Epub 2020 Aug 5.

Faculty of Pharmaceutical Sciences, Government College University Faisalabad, Faisalabad, Pakistan.

Introduction: Organ transplantation is a critically important procedure, which requires immune modulation by using immunosuppressants. Development of nanoparticles is an emerging and beneficial engineering process to increase the dissolution rate of poorly soluble immunosuppressants as well as to provide controlled release for better therapeutic outcomes.

Method: Currently, the nanoprecipitation method was employed to fabricate β-cyclodextrin (βCD) facilitated mycophenolate mofetil (MMF)-loaded solid lipid nanoparticles (SLNPs). The prime objectives of the study included, improvement of the dissolution profile of poorly aqueous soluble drug and controlled release from the SLNs to provide steady state drug concentration. Drug release from the prepared SLNs was assessed in two different media, ie, acidic buffer at pH 1.2 and phosphate buffer at pH 7.2 using USP dissolution apparatus for 12 h, followed by the evaluation of drug release mechanism and pattern by applying kinetic models.

Results: Justifiably, in acidic medium, the release was found to be 12% more (68%) in comparison to that in basic medium (56%). However, in both dissolution media, drug release was independent of initial concentration (R>0.95) with non-Fickian type of diffusion mechanism. The outcomes of the study have exhibited that prepared formulations were in nanosized range (80-170 nm) with a net charge of ±23 charge on their surface. They possessed fairly uniform surface with acceptable polydispersity index (0.23±0.09). Scanning electron microscopy (SEM) analysis illustrated that the nanoparticles had uniform particle size and shape.

Discussion: The findings show potential applications of the nanoparticles and the method for the development of SLNPs in controlled release of MMF for better therapeutic outcomes. Conclusively, the prepared SLNPs were well designed in nanosized ranges and justifying the once daily controlled release formulation dose of MMF to enhance patient compliance.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2147/IJN.S255636DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7428318PMC
November 2020

Ion-Cross-Linking-Promoted High-Performance Si/PEDOT:PSS Electrodes: The Importance of Cations' Ionic Potential and Softness Parameters.

ACS Appl Mater Interfaces 2020 Apr 15;12(17):19431-19438. Epub 2020 Apr 15.

Shanghai Electrochemical Energy Devices Research Center, School of Chemistry and Chemical Engineering and State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, P. R. China.

Pedot: PSS has been studied as a silicon-based binder due to its inherent superior electricity and electrochemical stability. However, it cannot effectively alleviate the huge volume changes of silicon during lithiation/delithiation due to its linear structure, resulting in poor cycling stability. Ion-cross-linking is a usual method to cross-link linear polymers into 3D structures. In this paper, multivalent cations of the 5th period and Group 2 cross-linked PEDOT:PSS were applied as silicon anode binders and studied systematically. It was found that the variation trend of viscosity and conductivity of PEDOT:PSS after cross-linking was consistent with that of ionic potential and softness parameters of multivalent cations. The mesostructure of a binder after cross-linking is influenced by the solubility product constant of sulfites or hydroxides of cations and the growth characteristics of crystals. An Sn-cross-linked binder displayed increased viscosity and electrical conductivity and higher reduced modulus and hardness due to its positive softness parameter and higher ion potential. The Si electrode with the Sn-cross-linked binder showed improved cycling stability (1876.4 mAh g compared with 1068.4 mAh g of the electrode with the pure PEDOT:PSS binder after 100 cycles) and superior rate capability (∼800 mAh g at an ultrahigh current density of 8.0 A g).
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acsami.0c00755DOI Listing
April 2020

Glycerol-crosslinked PEDOT:PSS as bifunctional binder for Si anodes: Improved interfacial compatibility and conductivity.

J Colloid Interface Sci 2020 Apr 13;565:270-277. Epub 2020 Jan 13.

Shanghai Electrochemical Energy Devices Research Center, School of Chemistry and Chemical Engineering and State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, China. Electronic address:

Developing conductive polymer binders is a new way to enhance the electric connectivity and mechanical contact of Si based anode material. While the linear structure of commercial PEDOT:PSS cannot effectively alleviate the volume expansion of Si. Herein, glycerol was introduced as a cross-linker to PEDOT:PSS binder for Si anodes, which can further improve the interfacial compatibility between silicon and PEDOT:PSS. After crosslinking, the peel force increased 2 times. As a result, the Si nanoparticles anode with the glycerol-crosslinked binder exhibited a high reversible capacity of 1951.5 mAh g after 200 cycles at 0.5 A g and superior rate capability (804 mAh g at a high current of 8.0 A g) for the inherent superior conductivity of PEDOT:PSS.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jcis.2020.01.028DOI Listing
April 2020

Early Neurodevelopmental Exposure to Low Lead Levels Induces Fronto-executive Dysfunctions That Are Recovered by Taurine Co-treatment in the Rat Attention Set-Shift Test: Implications for Taurine as a Psychopharmacotherapy Against Neurotoxicants.

Adv Exp Med Biol 2019 ;1155:821-846

SUNY Neuroscience Research Institute, SUNY Old Westbury, Old Westbury, NY, USA.

Lead (Pb) is a developmental neurotoxicant that causes lifelong cognitive dysfunctions. In particular, Pb-induced frontoexecutive dysfunctions emerge later in life when the cortex is fully myelinated, thereby permitting the ability to assess the extent to which Pb has developmentally impacted higher order cognitive and behavioral systems. The present study evaluated the effects of developmental Pb-exposure (150 ppm lead acetate in the drinking water) in Long Evans Hooded rats through the Attention Set-Shift Test (ASST) between postnatal days (PND) 60-90. Treatment groups were comprised of Control (0 ppm), Perinatal (150 ppm), and Perinatal+Taurine (150 ppm + 0.05% Taurine in the drinking water) rats (N = 36; n = 6 per treatment group for each sex). Frontoexecutive functions were evaluated based on trials-to-criterion (TTC) and errors-to-criterion (ETC) measures for simple and complex discriminations (SD & CD), intradimensional and extradimensional shifts (ID & ED), as well as reversals (Rev) of the CD, I-, and ED stages, respectively. Post-testing, the prelimbic (PrL), infralimbic (IL), orbital ventral frontal (OV), orbital ventro-lateral (OVL), and hippocampal (HP) brain regions were extracted and processed through Liquid Chromatography/Mass Spectrophotometry (LC/MS) for determining the GABA and Taurine ratios relative to Glutamate, Dopamine, Norepinephrine, Epinephrine, and Serotonin. The ASST data revealed that Perinatal rats are negatively impacted by developmental Pb-exposures evidenced by increased TTC and ETC to learn the SD, ID, and ID-Rev with unique sex-based differences in frontoexecutive dysfunctions. Moreover, Perinatal+Taurine co-treated rats exhibited a recovery of the frontoexecutive dysfunctions observed in Perinatal rats to levels equivalent to Control rats across both sexes. The LC/MS data revealed altered brain sub-region specific patterns across the PrL, IL, OV, OVL, and HP in response to developmental Pb-exposure that produced an altered neurochemical signaling profile in a sex-dependent manner, which may underlie the observed frontoexecutive dysfunctions, cognitive inflexibility, and associated motivation deficits. When taurine co-treatment was administered concurrently for the duration of developmental Pb-exposure, the observed frontoexecutive dysfunctions were significantly reduced in both ASST task performance and neurochemical ratios that were comparable to Control levels for both sexes. Altogether, the data suggest that taurine co-treatment may facilitate neuroprotection, mitigate neurotransmitter excitability balancing, and perhaps ameliorate against neurotoxicant exposures in early development as a potential psychopharmacotherapy.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/978-981-13-8023-5_70DOI Listing
September 2019

Assessing the Anxiolytic Properties of Taurine-Derived Compounds in Rats Following Developmental Lead Exposure: A Neurodevelopmental and Behavioral Pharmacological Pilot Study.

Adv Exp Med Biol 2019 ;1155:801-819

SUNY Neuroscience Research Institute, SUNY Old Westbury, Old Westbury, NY, USA.

Lead (Pb) is a developmental neurotoxicant that causes alterations in the brain's excitation-to-inhibition (E/I) balance. By increasing chloride concentration through GABA-ARs, taurine serves as an effective inhibitory compound for maintaining appropriate levels of brain excitability. Considering this pharmacological mechanism of taurine facilitated inhibition through the GABA-AR, the present pilot study sought to explore the anxiolytic potential of taurine derivatives. Treatment groups consisted of the following developmental Pb-exposures: Control (0 ppm) and Perinatal (150 ppm or 1000 ppm lead acetate in the drinking water). Rats were scheduled for behavioral tests between postnatal days (PND) 36-45 with random assignments to either solutions of Saline, Taurine, or Taurine Derived compounds (i.e., TD-101, TD-102, or TD-103) to assess the rats' responsiveness to each drug in mitigating the developmental Pb-exposure through the GABAergic system. Long Evans Hooded rats were assessed using an Open Field (OF) test for preliminary locomotor assessment. Approximately 24-h after the OF, the same rats were exposed to the Elevated Plus Maze (EPM) and were given an i.p. injection of 43 mg/Kg of the Saline, Taurine, or TD drugs 15-min prior to testing. Each rat was tested using the random assignment method for each pharmacological condition, which was conducted using a triple-blind procedure. The OF data revealed that locomotor activity was unaffected by Pb-exposure with no gender differences observed. However, Pb-exposure induced an anxiogenic response in the EPM, which interestingly, was ameliorated in a gender-specific manner in response to taurine and TD drugs. Female rats exhibited more anxiogenic behavior than the male rats; and as such, exhibited a greater degree of anxiety that were recovered in response to Taurine and its derivatives as a drug therapy. The results from the present psychopharmacological pilot study suggests that Taurine and its derivatives could provide useful data for further exploring the pharmacological mechanisms and actions of Taurine and the associated GABAergic receptor properties by which these compounds alleviate anxiety as a potential behavioral pharmacotherapy for treating anxiety and other associated mood disorders.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/978-981-13-8023-5_69DOI Listing
September 2019

Development and application of DNA-aptamer-coupled magnetic beads and aptasensors for the detection of oocysts in drinking and recreational water resources.

Can J Microbiol 2019 Nov 12;65(11):851-857. Epub 2019 Aug 12.

CREM Co Labs, Units 1-2, 3403 American Drive, Mississauga, ON L4V 1T4, Canada.

Environmentally stable and disinfectant-resistant oocysts of spp. shed in the feces of infected humans and animals frequently contaminate water resources and are subsequently spread via potable and recreational waters. The current monoclonal-antibody-based methods for detecting them in water are slow, labor-intensive, and demand skills to interpret the results. We have developed DNA-aptamer-based aptasensors, coupled with magnetic beads, to detect and identify the oocysts of for monitoring recreational and drinking water sources. A sensitive and specific electrochemical aptasensor (3'-biotinylated R4-6 aptamer) was used as a secondary ligand to bind the streptavidin-coated magnetic beads. This was incorporated into a probe using gold nanoparticle modified screen-printed carbon electrodes. Square wave voltammetry allowed for specific recognition of oocysts. The aptamer-coated probes had an oocyst detection limit of 50. It did not bind to the cysts of , another common waterborne pathogen, thus indicating its high specificity for the target pathogen. The system could successfully detect oocysts in spiked samples of the raw lake and river waters. Therefore, the combined use of the aptasensor and magnetic beads has the potential to monitor water quality for oocysts in field samples without relying on monoclonal antibodies and skill-demanding microscopy.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1139/cjm-2019-0153DOI Listing
November 2019

Prevalence and molecular characterization of DNA in retail fresh meats in Canada.

Food Waterborne Parasitol 2018 Dec 8;13:e00031. Epub 2018 Nov 8.

Bureau of Microbial Hazards, Food Directorate, Health Canada, 251 Sir Frederick Banting Driveway, Ottawa, ON K1A 0K9, Canada.

is a protozoan parasite which infects a wide variety of mammals and birds worldwide, including humans. Human toxoplasmosis is primarily transmitted through the ingestion of tissue cysts in raw or poorly cooked meat and organs of infected animals, or through the ingestion of oocysts in food, water or soil contaminated with cat faeces. There is a distinct paucity of information on the prevalence and molecular characteristics of in retail meats in Canada. This study reports the presence of DNA in 4.3% (12 of 281) of packages of fresh ground beef, chicken breasts and ground pork purchased at retail in three Canadian provinces. prevalence was very similar among all three meat types tested, and among the provinces sampled. Genotyping of positive samples by means of PCR-RFLP and DNA sequencing demonstrated the presence of both type II (66.7%) and type III (33.3%). These findings provide baseline data on the prevalence of DNA in fresh meats purchased at retail in Canada and will allow for more accurate and meaningful health risk assessments for the purposes of developing food safety guidelines and policies.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.fawpar.2018.e00031DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7034011PMC
December 2018

Toxoplasma gondii infection in stranded St. Lawrence Estuary beluga Delphinapterus leucas in Quebec, Canada.

Dis Aquat Organ 2018 09;130(3):165-175

Bureau of Microbial Hazards, Food Directorate, Health Canada, Ottawa, ON K1A 0K9, Canada.

The St. Lawrence Estuary (SLE) beluga Delphinapterus leucas in Quebec, Canada, is endangered due to intensive hunting in the 19th and 20th centuries and subsequent anthropogenic contamination and human activities in the region. Infectious disease is a primary cause of death in this population. The protozoan parasite Toxoplasma gondii is reported in numerous marine mammal species, including beluga. In the present study, 55 tissue samples (heart and brain) collected from 34 stranded SLE beluga were analysed by PCR followed by DNA sequencing and restriction fragment length polymorphism analysis (RFLP) to determine the PCR prevalence and genotypes of T. gondii in these beluga. Of 34 beluga tested, 44% were positive for T. gondii by PCR, with males having a higher prevalence of infection than females and with more infected neonates and juveniles than adults. Molecular analyses indicated that all T. gondii infecting stranded SLE beluga grouped into genotype II, which predominates in humans. While our results indicate that a high prevalence of stranded beluga are PCR-positive for T. gondii infection, very few deaths are attributed to toxoplasmosis based on published necropsy results. Toxoplasma gondii can cause a range of diseases, including neurological deficits, and more data are needed to investigate this parasite's effect on population recovery.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3354/dao03262DOI Listing
September 2018

4-quinolin-8-yloxy Linked Triphenylamine Based Polyimides: Blue Light Emissive and Potential Hole-Transport Materials.

J Fluoresc 2018 Jan 7;28(1):311-321. Epub 2017 Nov 7.

Department of Chemical and Biomolecular Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, South Korea.

A series of fluorescent donor- acceptor (D-A) alternating copolyimides (P1, P2, P3 and P4) with 4-quinolin-8-yloxy linked triphenylamine main polymer chain have been synthesized by conventional polycondensation. All the synthesized co-polyimides were characterized by elemental, gel permeation chromatography and FTIR spectral analysis. These newly prepared PIs possess HOMO energy levels in range of - 4.74 to - 4.78 eV and have medium optical band gaps. The photoluminescence spectral analysis revealed blue to violet emission with appreciable efficiency with lower onset oxidation potentials suitable for the facile hole injection materials. All the photophysical and electrochemical properties were also explored in context of effect of the pendant 4- quinolin-8-yloxy, indicating suitable combination of donor (TPA) on one hand and imide and pendant as acceptor on both ends.Graphical Abstract.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s10895-017-2193-0DOI Listing
January 2018

Synthesis and Photophysical Study of New Green Fluorescent TPA Based Poly(azomethine)s.

J Fluoresc 2017 Nov 15;27(6):2177-2186. Epub 2017 Aug 15.

Department of Chemical and Biomolecular Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, South Korea.

A series of poly(azomethine)s (PAMs) were synthesized from N-(4-aminophenyl)-N-(4-phenoxyphenyl)benzene-1,4-diamine (DA) and various dialdehydes to investigate the influence of structure of polymer chain and triphenylamine-based phenoxy pendant group on the optoelectronic properties. The structural characterization of the resulting poly(azomethine)s was carried out by solubility test, gel permeation chromatography, viscosity measurement, fourier transform infrared (FTIR) spectral and CHN elemental analysis. The photophysical and electrochemical properties of the materials were scrutinized by UV-vis, photoluminescence, time correlation photon counting spectral analysis (TCSP) and cyclic voltammetry. The thermal stability of the poly(azomethine)s was assessed by differential scanning calorimetry and thermogravimetric analysis found to be stable upto 300 °C. These polymers exhibit moderate inherent viscosity range from 0.99 to 1.15 g dL and appreciable organosolubility. The presence of triphenylamine and azomethine (CH = N) linkage in our synthesized materials rendered them fluorescent, emitting green light upon excitation at 375 nm with quantum efficiencies of 3.9-8.5%. The pendant phenoxy group at para-position in new poly(azomethine)s has also lowered the onset oxidation potentials and elevated the HOMO levels. Additionally, the presence of conjugation increases the fluorescence time of the excited state in conjugated polymers which was found in the range 9.22-11.17 ns, sufficient to be use in future optoelectronic applications.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s10895-017-2157-4DOI Listing
November 2017

Multi-scale occupancy approach to estimate Toxoplasma gondii prevalence and detection probability in tissues: an application and guide for field sampling.

Int J Parasitol 2016 08 4;46(9):563-70. Epub 2016 May 4.

Department of Veterinary Microbiology, University of Saskatchewan, 52 Campus Drive, Saskatoon, Saskatchewan S7N 5B4, Canada.

Increasingly, birds are recognised as important hosts for the ubiquitous parasite Toxoplasma gondii, although little experimental evidence exists to determine which tissues should be tested to maximise the detection probability of T. gondii. Also, Arctic-nesting geese are suspected to be important sources of T. gondii in terrestrial Arctic ecosystems, but the parasite has not previously been reported in the tissues of these geese. Using a domestic goose model, we applied a multi-scale occupancy framework to demonstrate that the probability of detection of T. gondii was highest in the brain (0.689, 95% confidence interval=0.486, 0.839) and the heart (0.809, 95% confidence interval=0.693, 0.888). Inoculated geese had an estimated T. gondii infection probability of 0.849, (95% confidence interval=0.643, 0.946), highlighting uncertainty in the system, even under experimental conditions. Guided by these results, we tested the brains and hearts of wild Ross's Geese (Chen rossii, n=50) and Lesser Snow Geese (Chen caerulescens, n=50) from Karrak Lake, Nunavut, Canada. We detected 51 suspected positive tissue samples from 33 wild geese using real-time PCR with melt-curve analysis. The wild goose prevalence estimates generated by our multi-scale occupancy analysis were higher than the naïve estimates of prevalence, indicating that multiple PCR repetitions on the same organs and testing more than one organ could improve T. gondii detection. Genetic characterisation revealed Type III T. gondii alleles in six wild geese and Sarcocystis spp. in 25 samples. Our study demonstrates that Arctic nesting geese are capable of harbouring T. gondii in their tissues and could transport the parasite from their southern overwintering grounds into the Arctic region. We demonstrate how a multi-scale occupancy framework can be used in a domestic animal model to guide resource-limited sample collection and tissue analysis in wildlife. Secondly, we confirm the value of traditional occupancy in optimising T. gondii detection probability in tissue samples.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ijpara.2016.04.003DOI Listing
August 2016

Cryptosporidium hominis Is a Newly Recognized Pathogen in the Arctic Region of Nunavik, Canada: Molecular Characterization of an Outbreak.

PLoS Negl Trop Dis 2016 Apr 8;10(4):e0004534. Epub 2016 Apr 8.

J.D. MacLean Centre for Tropical Diseases, McGill University Health Centre, Montreal, Canada.

Background: Cryptosporidium is a leading cause of childhood diarrhea in low-resource settings, and has been repeatedly associated with impaired physical and cognitive development. In May 2013, an outbreak of diarrhea caused by Cryptosporidium hominis was identified in the Arctic region of Nunavik, Quebec. Human cryptosporidiosis transmission was previously unknown in this region, and very few previous studies have reported it elsewhere in the Arctic. We report clinical, molecular, and epidemiologic details of a multi-village Cryptosporidium outbreak in the Canadian Arctic.

Methodology/principal Findings: We investigated the occurrence of cryptosporidiosis using a descriptive study of cases with onset between April 2013 and April 2014. Cases were defined as Nunavik inhabitants of any age presenting with diarrhea of any duration, in whom Cryptosporidium oocysts were detected by stool microscopy in a specialised reference laboratory. Cryptosporidium was identified in stool from 51 of 283 individuals. The overall annual incidence rate (IR) was 420 / 100,000 inhabitants. The IR was highest among children aged less than 5 years (1290 /100,000 persons). Genetic subtyping for stool specimens from 14/51 cases was determined by DNA sequence analysis of the 60 kDa glycoprotein (gp60) gene. Sequences aligned with C. hominis subtype Id in all cases. No common food or water source of infection was identified.

Conclusions/significance: In this first observed outbreak of human cryptosporidiosis in this Arctic region, the high IR seen is cause for concern about the possible long-term effects on growth and development of children in Inuit communities, who face myriad other challenges such as overcrowding and food-insecurity. The temporal and geographic distribution of cases, as well as the identification of C. hominis subtype Id, suggest anthroponotic rather than zoonotic transmission. Barriers to timely diagnosis delayed the recognition of human cryptosporidiosis in this remote setting.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1371/journal.pntd.0004534DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4825996PMC
April 2016

Detection of Cryptosporidium parvum Oocysts on Fresh Produce Using DNA Aptamers.

PLoS One 2015 3;10(9):e0137455. Epub 2015 Sep 3.

Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario, Canada.

There are currently no standard methods for the detection of Cryptosporidium spp., or other protozoan parasites, in foods, and existing methods are often inadequate, with low and variable recovery efficiencies. Food testing is difficult due to the low concentrations of parasites, the difficulty in eluting parasites from some foods, the lack of enrichment methods, and the presence of PCR inhibitors. The main objectives of the present study were to obtain DNA aptamers binding to the oocyst wall of C. parvum, and to use the aptamers to detect the presence of this parasite in foods. DNA aptamers were selected against C. parvum oocysts using SELEX (Systematic Evolution of Ligands by EXponential enrichment). Ten rounds of selection led to the discovery of 14 aptamer clones with high affinities for C. parvum oocysts. For detecting parasite-bound aptamers, a simple electrochemical sensor was employed, which used a gold nanoparticle-modified screen-printed carbon electrode. This aptasensor was fabricated by self-assembling a hybrid of a thiolated ssDNA primer and the anti- C. parvum aptamer. Square wave voltammetry was employed to quantitate C. parvum in the range of 150 to 800 oocysts, with a detection limit of approximately 100 oocysts. The high sensitivity and specificity of the developed aptasensor suggests that this novel method is very promising for the detection and identification of C. parvum oocysts on spiked fresh fruits, as compared to conventional methods such as microscopy and PCR.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0137455PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4559477PMC
May 2016

Prevalence and molecular characterization of Cryptosporidium spp. and Giardia duodenalis in diarrhoeic patients in the Qikiqtani Region, Nunavut, Canada.

Int J Circumpolar Health 2015 19;74:27713. Epub 2015 Jun 19.

Bureau of Microbial Hazards, Food Directorate, Health Canada, Ottawa, ON, Canada;

Background: Although the prevalences of infection with the protozoan parasites Cryptosporidium spp. and Giardia duodenalis in humans appear to be relatively high in the Canadian North, their transmission patterns are poorly understood.

Objective: To determine the detection rate and the molecular characteristics of Cryptosporidium spp. and Giardia duodenalis in diarrhoeic patients in the Qikiqtani (Baffin Island) Region of Nunavut, Canada, in order to better understand the burden of illness and the potential mechanisms of transmission.

Study Design/methods: Diarrhoeal stool specimens (n=108) submitted to the Qikiqtani General Hospital for clinical testing were also tested for the presence of Cryptosporidium spp. and Giardia duodenalis using epifluorescence microscopy and polymerase chain reaction (PCR). DNA sequencing and restriction fragment length polymorphism (RFLP) analyses were performed on PCR-positive specimens to determine the species, genotypes and sub-genotypes of the parasites.

Results: Cryptosporidium was detected in 15.7% of the diarrhoeic patients, while Giardia was detected in 4.6%. DNA sequencing of a fragment of the small subunit rRNA gene indicated that all of the Cryptosporidium amplicons had a 100% homology to C. parvum, and a gp60 assay showed that all aligned with C. parvum sub-genotype IIa. Microsatellite analysis revealed 3 cases of sub-genotype IIaA15G2R1, 2 of IIaA15G1R and 1 case each of sub-genotypes IIaA16G1R1 and IIaA15R1. For Giardia, results based on the amplification of both the 16S rRNA gene and the gdh gene were generally in agreement, and both DNA sequencing and RFLP demonstrated the presence of the G. duodenalis Assemblage B genotype.

Conclusions: Both C. parvum and G. duodenalis Assemblage B were present in human diarrhoeal stool specimens from Nunavut, which was suggestive of zoonotic transmission, although human-to-human transmission cannot be ruled out. To fully understand the public health significance of the different Cryptosporidium and Giardia species and genotypes in diarrhoeic patients, it will be imperative to establish the extent of genetic diversity within these parasites through comprehensive studies of the molecular epidemiology of cryptosporidiosis and giardiasis in the Nunavut region.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4475686PMC
http://dx.doi.org/10.3402/ijch.v74.27713DOI Listing
November 2016

4-Nitro-phenyl 2-chloro-benzoate.

Acta Crystallogr Sect E Struct Rep Online 2013 Jan 15;69(Pt 1):o96. Epub 2012 Dec 15.

Department of Chemistry, Quaid-I-Azam University, Islamabad 45320, Pakistan.

The aromatic rings in the title compound, C13H8ClNO4, enclose a dihedral angle of 39.53 (3)°. The nitro group is almost coplanar with the ring to which it is attached [dihedral angle = 4.31 (1)°]. In the crystal, mol-ecules are connected by C-H⋯O hydrogen bonds into chains running along [001].
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1107/S1600536812050362DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3588303PMC
January 2013

High diversity of Cryptosporidium subgenotypes identified in Malaysian HIV/AIDS individuals targeting gp60 gene.

PLoS One 2012 8;7(2):e31139. Epub 2012 Feb 8.

Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia.

Background: Currently, there is a lack of vital information in the genetic makeup of Cryptosporidium especially in developing countries. The present study aimed at determining the genotypes and subgenotypes of Cryptosporidium in hospitalized Malaysian human immunodeficiency virus (HIV) positive patients.

Methodology/principal Findings: In this study, 346 faecal samples collected from Malaysian HIV positive patients were genetically analysed via PCR targeting the 60 kDa glycoprotein (gp60) gene. Eighteen (5.2% of 346) isolates were determined as Cryptosporidium positive with 72.2% (of 18) identified as Cryptosporidium parvum whilst 27.7% as Cryptosporidium hominis. Further gp60 analysis revealed C. parvum belonging to subgenotypes IIaA13G1R1 (2 isolates), IIaA13G2R1 (2 isolates), IIaA14G2R1 (3 isolates), IIaA15G2R1 (5 isolates) and IIdA15G1R1 (1 isolate). C. hominis was represented by subgenotypes IaA14R1 (2 isolates), IaA18R1 (1 isolate) and IbA10G2R2 (2 isolates).

Conclusions/significance: These findings highlighted the presence of high diversity of Cryptosporidium subgenotypes among Malaysian HIV infected individuals. The predominance of the C. parvum subgenotypes signified the possibility of zoonotic as well as anthroponotic transmissions of cryptosporidiosis in HIV infected individuals.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0031139PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3275556PMC
July 2012

First genetic classification of Cryptosporidium and Giardia from HIV/AIDS patients in Malaysia.

Infect Genet Evol 2011 Jul 23;11(5):968-74. Epub 2011 Mar 23.

Department of Veterinary Science, The University of Melbourne, 250 Princes Highway, Werribee, Victoria 3030, Australia.

Given the HIV epidemic in Malaysia, genetic information on opportunistic pathogens, such as Cryptosporidium and Giardia, in HIV/AIDS patients is pivotal to enhance our understanding of epidemiology, patient care, management and disease surveillance. In the present study, 122 faecal samples from HIV/AIDS patients were examined for the presence of Cryptosporidium oocysts and Giardia cysts using a conventional coproscopic approach. Such oocysts and cysts were detected in 22.1% and 5.7% of the 122 faecal samples, respectively. Genomic DNAs from selected samples were tested in a nested-PCR, targeting regions of the small subunit (SSU) of nuclear ribosomal RNA and the 60kDa glycoprotein (gp60) genes (for Cryptosporidium), and the triose-phosphate isomerase (tpi) gene (for Giardia), followed by direct sequencing. The sequencing of amplicons derived from SSU revealed that Cryptosporidium parvum was the most frequently detected species (64% of 25 samples tested), followed by C. hominis (24%), C. meleagridis (8%) and C. felis (4%). Sequencing of a region of gp60 identified C. parvum subgenotype IIdA15G2R1 and C. hominis subgenotypes IaA14R1, IbA10G2R2, IdA15R2, IeA11G2T3R1 and IfA11G1R2. Sequencing of amplicons derived from tpi revealed G. duodenalis assemblage A, which is of zoonotic importance. This is the first report of C. hominis, C. meleagridis and C. felis from Malaysian HIV/AIDS patients. Future work should focus on an extensive analysis of Cryptosporidium and Giardia in such patients as well as in domestic and wild animals, in order to improve the understanding of transmission patterns and dynamics in Malaysia. It would also be particularly interesting to establish the relationship among clinical manifestation, CD4 cell counts and genotypes/subgenotypes of Cryptosporidium and Giardia in HIV/AIDS patients. Such insights would assist in a better management of clinical disease in immuno-deficient patients as well as improved preventive and control strategies.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.meegid.2011.03.007DOI Listing
July 2011

Family functioning in the caregivers of patients with dementia.

Int J Geriatr Psychiatry 2004 Jun;19(6):533-7

Butler Hospital, Brown University School of Medicine, Providence, Rhode Island 02906, USA.

Background: Caregiver burden has been extensively studied in the dementia population. The marital relationship has been suggested as a mediational model through which variables influence the caregiver and contribute to the experience of burden or reward.

Objectives: This study examines family functioning, caregiver burden and reward and quality of life in 38 family members caring for a relative with dementia.

Methods: Caregivers of out-patients with dementia completed self report questionnaires.

Results: 63% of caregivers were female with a mean age of 62 years. Patient mean age was 73 years. The average number of caregiving years was 3.1. Caregivers were more likely to be spouses (61%) than children (29%) or other relatives (11%). Despite the fact that caregivers reported that their relatives were moderately disabled, they perceived more reward than burden. Caregivers who reported poor family functioning had higher ratings of strain and burden. Family functioning in these caregivers was poorest in the dimensions of affective responsiveness, problem solving and communication but it was also impaired in roles and affective involvement.

Conclusions: Assessing a family's functioning may be an important factor in the care of the dementia patient and his/her family.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/gps.1119DOI Listing
June 2004
-->