215 research outputs found
All organic memory devices utilizing C60 molecules and insulating polymers
No full textThe convergence of mobile technologies combined with stricter power requirements and increasing demands have strained the current memory technology. Newer technologies such as phase changing, ferroelectric, and magnetic random access memories are unsatisfactory in meeting the new requirements. We propose a new memory technology based on our initial discovery of charge storage in C60 molecules within poly (4-vinyl phenol) (PVP). To understand the memory potential, we created single-layer devices consisting of ~30nm films of PVP+C60 sandwiched between aluminum (Al) electrodes. Current versus voltage (I-V) sweeps showed a significant hysteresis of 75nA, with distinguishable memory states. Room temperature charging of C60 was confirmed indirectly through capacitance versus voltage measurements and directly by monitoring the A1g characteristic peak of C60 during Raman measurements. We demonstrated memory operations by applying read-write-erase (RWE) pulses. The PVP+C60 devices exhibited memory retention for over 1 hour and response times of around 10ns. Characteristic hysteresis was demonstrated at the nanoscale. Conduction models were fitted at room temperature to the I-V curves. It was found that combination of direct and Fowler-Nordheim tunneling were the principle conduction mechanisms.
For a more technologically viable memory device, we developed a multi-layer device structure, consisting of a polystyrene (PS) capping layer. The resulting asymmetrical I-V curve exhibited a hysteresis ratio of 103. RWE cycles were measured with clearly distinguishable states. The memory retentions were measured over 2 hours and the response time around 10ns. The stability of the multi-layer devices was improved. I-V measurements at temperatures varying from 4.2 K to 298 K were performed to construct a theoretical model. The I-V curves were found to be temperature independent and exhibited similar tunneling behaviors as the single-layer devices. A simple model for conduction and memory operation is proposed based on the I-V fits.
These devices exhibit the characteristics needed to satisfy the new demands for memory application and have the potential of becoming the first universal memory technology. They possess the high speed, non-volatility, thermal stability, and potentially high memory densities to make them ideal for use in laptops, iPhones, mp3 players, portable video players, GPS systems, and other mobile devices.Ph.D.Includes bibliographical references
Evaluation of the Immunogenicity of T and B Cell Epitopes from the S And M Proteins of Sars-Cov-2 Wuhan and Omicron Strains in Balb/C Mice
No full textThe coronavirus disease (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in numerous infections and deaths. The emergence of SARS-CoV-2 variants of concern (VOCs) resulted in reductions in the protective efficacies of current mRNA and viral-vectored vaccines targeting the spike (S) protein from the SARS-CoV-2 Wuhan strain. A more promising strategy involves targeting highly conserved and immunogenic sequences from SARS-CoV-2 structural proteins to produce immune responses against the Wuhan strain and circulating VOCs. Recombinant protein vaccines could serve as a valuable vaccine development platform based on their high stability, safety, and immunogenicity in clinical development. This research project aimed to develop a recombinant protein vaccine against SARS-CoV-2. Antigens were identified through literature mining and derived from the SARS-CoV-2 S and membrane (M) in the form of six peptides specifying highly conserved B cell and T cell epitopes. The expressed recombinant protein of interest, GST-6Phis, was purified through ammonium sulphate precipitation, gel filtration, immobilized metal affinity chromatography (IMAC), nickel-nitrilotriacetic acid (Ni-NTA) histidine affinity chromatography, and a protein concentrator. Four groups of 5 BALB/c mice each were intramuscularly or intranasally immunized with 10 µg GST-6Phis or with PBS. Cellular and humoral responses were evaluated at 42 days’ post-immunization. Intramuscular administration of GST-6Phis resulted in IFN-γ secreting CD4+ T cells, while intranasal administration produced IFN-γ secreting CD8+ T cells. Robust IgG antibody responses, as represented by absorbance values and mean reciprocal antibody titters, resulted from the intramuscular and intranasal administration of GST-6Phis. Sera obtained from mice immunized both intramuscularly and intranasally with GST-6Phis contained neutralizing antibodies against the SARS-CoV-2 Wuhan strain, while intramuscular administration produced neutralizing antibodies against Omicron. In conclusion, the recombinant protein vaccine demonstrated the promise of utilizing conserved and immunogenic epitopes to produce immune responses against both the SARS-CoV-2 Wuhan and Omicron strains
LAHORE DURING THE GHANAVID PERIOD A SOCIO POLITICAL AND CULTURAL STUDY
No full textMost of the historical documents and books are quiet about the art and craft produced in the early Muslim period of Lahore except for some sketchy information that we glimpse in different accounts. Before the arrival of Islam, Raja Jai Pal ruled Punjab. Mahmud of Ghazna conquered Lahore in 1021 AD. Hazrat Ali Hujveri, Husain Zanjani and Syed Ismael Muhaddis are worth mentioning scholars who lived in Lahore during Ghaznavid period. The city was full of cultural and artistic activities but the information about them is very scarce. An interesting source of information is the poetry written in that period by the poets of Lahore. These literary accounts give us references of architecture, painting, calligraphy, music and dance of Lahore
Research on Library and Information Science Services by Pakistani Authors from 2011 to 2020
No full textThe main objective of the current study is to quantify the research productivity in Library and Information Science (LIS) Services produced by Pakistani authors during the period of ten years from 2011 to 2020. The retrospective research method by applying the bibliometric technique has been used. The data of the publications on LIS Services by Pakistani authors has been browsed from various online and print sources. The selected bibliographic parameters of publications were inserted in Microsoft Excel-2016 for data analysis. The findings have been presented in tabular and graphic formats. A total of 1,258 documents were identified, contributed by 3,110 authors including multiple counts with an average of 2.47 authors per document. As a distinct name, a total of 858 authors were recognized and the share of international authors was slightly more than one-fifth (21%). About one-third of the total documents were published in the last two years of the study. Eighty-three percent of the documents were the results of research collaboration and the two-author pattern was found the preferred authorship pattern. The majority of documents (91%) were published as journals articles, followed by conference papers, book chapters and books. The highest number of papers were published in Pakistan Library and Information Science Journal, followed by Library Philosophy and Practice (e-journal). Sixty-four percent of the authors contributed in one paper each while 69 authors contributed ten or more than ten papers each. Dr. Rubina Bhatti, Dr. Kanwal Ameen and Dr. Khalid Mahmood were found the top-three most productive authors with 103, 94 and 77 publications, respectively. The introduction of LIS doctorate programs and the establishment of the National Digital Library of Higher Education Commission put a healthy impact on the growth of publications. There is a need to inspire the practicing librarians that they should come forward to contribute to the research progress to develop LIS services
TRADITIONAL MATERIALS USED BY THE MINIATURE ARTISTS AN INTRODUCTORY STUDY
No full textPrevious generations of the artists evolved special methods of producing materials for their art works meant to last for centuries. Their success can be appreciated by the existence to day of centuries old paintings in private collections hanging in different museums of the world, whose papers are intact and colours are as fresh as new. Unfortunately not much has ever been documented because this was the kind of knowledge that traveled orally from generation to generation. Some meager documents that are available, does give the basic idea but much of that documentation need further research and verification because many of the materials and methods explained are not very authentic. The paper is an effort to investigate and research some materials used by the past artists on scientific basis
The development of DNA vaccines against SARS-CoV-2
No full textBackground
The COVID-19 pandemic exerted significant impacts on public health and global economy. Research efforts to develop vaccines at warp speed against SARS-CoV-2 led to novel mRNA, viral vectored, and inactivated vaccines being administered. The current COVID-19 vaccines incorporate the full S protein of the SARS-CoV-2 Wuhan strain but rapidly emerging variants of concern (VOCs) have led to significant reductions in protective efficacies. There is an urgent need to develop next-generation vaccines which could effectively prevent COVID-19.
Methods
PubMed and Google Scholar were systematically reviewed for peer-reviewed papers up to January 2023.
Results
A promising solution to the problem of emerging variants is a DNA vaccine platform since it can be easily modified. Besides expressing whole protein antigens, DNA vaccines can also be constructed to include specific nucleotide genes encoding highly conserved and immunogenic epitopes from the S protein as well as from other structural/non-structural proteins to develop effective vaccines against VOCs. DNA vaccines are associated with low transfection efficiencies which could be enhanced by chemical, genetic, and molecular adjuvants as well as delivery systems.
Conclusions
The DNA vaccine platform offers a promising solution to the design of effective vaccines. The challenge of limited immunogenicity in humans might be solved through the use of genetic modifications such as the addition of nuclear localization signal (NLS) peptide gene, strong promoters, MARs, introns, TLR agonists, CD40L, and the development of appropriate delivery systems utilizing nanoparticles to increase uptake by APCs in enhancing the induction of potent immune responses
The Promising Potential of Reverse Vaccinology-Based Next-Generation Vaccine Development over Conventional Vaccines against Antibiotic-Resistant Bacteria
No full textThe clinical use of antibiotics has led to the emergence of multidrug-resistant (MDR) bacteria, leading to the current antibiotic resistance crisis. To address this issue, next-generation vaccines are being developed to prevent antimicrobial resistance caused by MDR bacteria. Traditional vaccine platforms, such as inactivated vaccines (IVs) and live attenuated vaccines (LAVs), were effective in preventing bacterial infections. However, they have shown reduced efficacy against emerging antibiotic-resistant bacteria, including MDR M. tuberculosis. Additionally, the large-scale production of LAVs and IVs requires the growth of live pathogenic microorganisms. A more promising approach for the accelerated development of vaccines against antibiotic-resistant bacteria involves the use of in silico immunoinformatics techniques and reverse vaccinology. The bioinformatics approach can identify highly conserved antigenic targets capable of providing broader protection against emerging drug-resistant bacteria. Multi-epitope vaccines, such as recombinant protein-, DNA-, or mRNA-based vaccines, which incorporate several antigenic targets, offer the potential for accelerated development timelines. This review evaluates the potential of next-generation vaccine development based on the reverse vaccinology approach and highlights the development of safe and immunogenic vaccines through relevant examples from successful preclinical and clinical studies
Integrating gender equality and social inclusion for integrated water resources management: a cheat sheet for practitioners
No full textPower walk activity: a tool adapted for the water sector
No full textThe Power Walk is a group role-playing exercise designed to prompt reflection on power dynamics, privilege, and social inequalities, adapted for the water sector context. The activity simulates a society where individuals have an equal starting point but depending on their social identities end up in different positions. The game is meant to convey gender equality and social inclusion (GESI) concepts in the water sector
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