skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Attention:

The NSF Public Access Repository (PAR) system and access will be unavailable from 10:00 PM ET on Friday, February 6 until 10:00 AM ET on Saturday, February 7 due to maintenance. We apologize for the inconvenience.


Search for: All records

Creators/Authors contains: "Sarwar, Muhammad"

Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher. Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?

Some links on this page may take you to non-federal websites. Their policies may differ from this site.

  1. Abstract Copper ions in wastewater present substantial environmental hazards, toxic to aquatic species and prone to bioaccumulation. Addressing this, we present a novel cross‐linked polythiourethane (C‐PTU) as a promising chelating adsorbent for the effective removal of copper ions from wastewater. A new monomer, 5‐(2,2,2‐trifluoroacetamide) benzene‐1,3‐bis(carbonyl) isothiocyanate (TFA‐ITC), was synthesized and further condensed with a 1,4‐butane diol to produce a trifluoroacetamide functionalized polythiourethane (TFA‐PTU) and subsequently generating amine functionalized polythiourethane (A‐PTU). The cross‐linking reaction was carried out through amino groups present on the polymer backbone with terephthaloyl chloride, resulting in the formation of C‐PTU. The monomer and polymers underwent characterization using Fourier transform infrared,1H, and13C nuclear magnetic resonance spectroscopy, with X‐ray diffraction analyzing the resin's chain alignment. Thermogravimetric and differential scanning calorimetry assessed C‐PTU's thermal properties. The adsorption process for Cu(II) ions was studied using atomic absorption spectroscopy, optimizing conditions for maximal uptake. Results revealed that C‐PTU exhibited a significant adsorption capacity for Cu(II) ions, reaching 67% after a 2 h contact time, with optimal adsorption occurring at pH 6. The Langmuir adsorption isotherm described the sorption mechanism, indicating favorable monolayer cation adsorption via coordination with donor sites on C‐PTU. This research presents a viable solution for copper ion contamination in wastewater, illustrating C‐PTU as an efficient, environmentally friendly adsorbent, marking progress toward cleaner water resources. 
    more » « less
  2. Benoit Lavraud (Ed.)
    The amateur radio community is a global, highly engaged, and technical community with an intense interest in space weather, its underlying physics, and how it impacts radio communications. The large-scale observational capabilities of distributed instrumentation fielded by amateur radio operators and radio science enthusiasts offers a tremendous opportunity to advance the fields of heliophysics, radio science, and space weather. Well-established amateur radio networks like the RBN, WSPRNet, and PSKReporter already provide rich, ever-growing, long-term data of bottomside ionospheric observations. Up-and-coming purpose-built citizen science networks, and their associated novel instruments, offer opportunities for citizen scientists, professional researchers, and industry to field networks for specific science questions and operational needs. Here, we discuss the scientific and technical capabilities of the global amateur radio community, review methods of collaboration between the amateur radio and professional scientific community, and review recent peer-reviewed studies that have made use of amateur radio data and methods. Finally, we present recommendations submitted to the U.S. National Academy of Science Decadal Survey for Solar and Space Physics (Heliophysics) 2024–2033 for using amateur radio to further advance heliophysics and for fostering deeper collaborations between the professional science and amateur radio communities. Technical recommendations include increasing support for distributed instrumentation fielded by amateur radio operators and citizen scientists, developing novel transmissions of RF signals that can be used in citizen science experiments, developing new amateur radio modes that simultaneously allow for communications and ionospheric sounding, and formally incorporating the amateur radio community and its observational assets into the Space Weather R2O2R framework. Collaborative recommendations include allocating resources for amateur radio citizen science research projects and activities, developing amateur radio research and educational activities in collaboration with leading organizations within the amateur radio community, facilitating communication and collegiality between professional researchers and amateurs, ensuring that proposed projects are of a mutual benefit to both the professional research and amateur radio communities, and working towards diverse, equitable, and inclusive communities. 
    more » « less