Magnetic Resonance Lithography with Nanometer Resolution

We propose an approach for super-resolution optical lithography which is based on the inverse of magnetic resonance imaging (MRI). The technique uses atomic coherence in an ensemble of spin systems whose final state population can be optically detected. In principle, our method is capable of producing arbitrary one and two dimensional high-resolution patterns with high contrast

Evaluation of Glibenclamide Quality and Stakeholders’ Perception of Medicine Quality in the Clinical Settings of the Ministry of Interior in Saudi Arabia

Aim: To explore medicine quality and perception among the stakeholders in the Ministry of Interior Medical Services (MOI-MSD) clinical settings in Saudi Arabia using glibenclamide as an indicator. Method: A mixed method approach was used in two phases. Phase one involved chemical analysis for identity and quantity of the active pharmaceutical ingredient (API), visual analysis and authentication of source of a popular diabetes medicine (glibenclamide) collected from MOI-MSD general warehouse in Riyadh, Saudi Arabia. Phase two contained a focus group discussion, self-completed survey questionnaires and semi-structured interviews to explore the perceptions of various stakeholders including commissioners, physicians, pharmacists and patients in the MOI-MSD settings in Saudi Arabia about medicine quality and related problems. Data analysis: Phase one collected quantitative data of API quantity from the chemical analysis of glibenclamide samples using a high performance liquid chromatography apparatus (HPLC) based on United States Pharmacopoeia (USP 36) method. The visual inspection of glibenclamide samples was performed using tool kit developed by The World Health Professions Alliance (WHPA) and The International Pharmaceutical Federation (FIP). The authentication of glibenclamide source was performed by on-site comparison of available samples in the general MOI-MSD warehouse with the available official reception documents. Phase two collected quantitative and qualitative data regarding perceptions about medicine quality and related problems and subsequently analysed them using SPSS for descriptive statistics and NVivo version 10 for thematic analysis following data coding and the development of themes and sub-themes. Subsequently, stakeholders’ data were triangulated to establish common and specific themes and sub-themes among MOI-MSD stakeholders. Findings: Phase one of the study found that all glibenclamide samples were within acceptable USP limits in terms of identity and quantity between 90-110%. It was also found that all available glibenclamide batch numbers were present in the official reception documents and the visual analysis of samples revealed no visible errors on the medicine samples or its packaging. Phase two of the study found that most stakeholders, particularly commissioners and physicians, believed that medicine quality was good or excellent in Saudi Arabia. However, the commissioners, physicians and pharmacists believed that the quality of medicines in the MOI-MSD was less than what is available in Saudi Arabia but patients mostly disagreed with these views. Most patients believed that the quality of medicines was high in both the Saudi Arabian market and in the MOI-MSD settings. Limited knowledge about good quality medicines and counterfeit medicines was found among most stakeholders where the quality of medicines was commonly associated with the effect rather than technical attributes of medicines including content, appearance and source. The stakeholders in this study reported a wide range of behaviour when in doubt about medicine quality such as reporting these doubts to authorities, finding alternative medicines, stopping the medicine use and taking no further action regarding these doubts. Furthermore, all stakeholders have identified medicine procurement focusing on price rather than quality, difficulty in reporting medicine quality problems and medicine storage conditions as challenges to medicine quality in the MOI-MSD. Patients, particularly chronic patients from Jeddah city, have complained about medicine non-availability in their local MOI-MSD primary clinic and expensive medicine prices. Conclusions: Glibenclamide quality in the MOI-MSD settings was found to be acceptable in terms of API identity and quantity, source and visual appearance. The perception about medicine quality in these settings seems to be low particularly from commissioners and pharmacists but not the patients. There is an urgent need to implement quality assurance steps to increase the commissioners and pharmacists trust in the quality of their medicines at the medicine selection, procurement, storage and transportation stages in addition to improving the accessibility to report medicine quality problems to all stakeholders. Subsequently, future research is needed to measure and evaluate the impact of these quality assurance steps on the confidence of commissioners and pharmacists trust in the quality of the MOI-MSD medicines. Furthermore, patients’ issues about medicine non-availability need to be addressed rapidly as it could result in patients’ acquiring medicines from unknown sources and/or cause additional financial burdens

Engineering of Diamond Based Sensor for Nano-Scale Magnetic Field Sources

Diamond-based magnetometry utilizes the negatively charged nitrogen-vacancy color center NV. For sensing nano-scale magnetic field sources, the small size of the NV is a great advantage over other magnetometers. However, conventional implantation and growth techniques fail to produce very shallow NVs which can be brought to close proximity of small magnetic field sources. Here, we investigate innovative implantation and growth techniques to address this problem. For bulk diamond, we were able to create a concentrated layer of NVs approximately 2nm for the diamond surface. Direct measurement of magnetic sensitivity for this layer yields a sensitivity of 125nT µm³/²∕√ Hz. For currents running in nano-scale wires on the diamond surface this translates to sensitivities below fA/√ Hz. To produce superior nanodiamond magnetic sensor, we attempt growth of fluorescent nanodiamonds using two methods, High-Pressure-High-Temperature (HPHT), and plasma enhanced chemical vapor deposition CVD. We show results for fluorescent nanodiamond grown around 1-adamantylamine seed molecule. We show that the nitrogen in the seed molecule was successfully transformed to NV through electron irradiation at high temperature. Also, we show results of fluorescent nanodiamonds grown using a home built plasma CVD system. Nitrogen was introduced to the diamond by adding trimethylamine to the reactor chamber. Once again, the diamond was not fluorescent until after electron irradiation at high temperature

Fluorescent nanodiamonds: past, present, and future

Multi-color fluorescent nanodiamonds (FNDs) containing a variety of color centers are promising fluorescent markers for biomedical applications. Compared to colloidal quantum dots and organic dyes, FNDs have the advantage of lower toxicity, exceptional chemical stability, and better photostability. They can be surface functionalized by techniques similar to those used for other nanoparticles. They exhibit a variety of emission wavelengths from visible to near infrared, with narrow or broad bandwidths depending on their color centers. In addition, some color centers can detect changes in magnetic fields, electric fields, and temperature. In this article review, we will discuss the current trends in FND’s development, including comparison to the early development of quantum dots. We will also highlight some of the latest advances in fabrication, as well as demonstrations of their use in bioimaging and biosensing

Lanthanide ions doped in vanadium oxide for sensitive optical glucose detection

Blood glucose monitoring is essential to avoid the unwanted consequences of glucose level fluctuations. Optical monitors are of special interest because they can be non-invasive. Among optical glucose sensors, fluorescent upconversion nanoparticles (UCNPs) have the advantage of good photostability, low toxicity, and exceptional autofluorescence suppression. However, to sense glucose, UCNPs normally need surface functionalization, and this can be easily affected by other factors in biological systems, and may also affect their ability for real-time sensing of both increasing and decreasing glucose levels. Here, we report YVO4 : Yb3+, Er3+@Nd3+core/shell UCNPs with Nd and Yb shell and GdVO4 : Yb3+, Er3+@Nd3+ core/shell UCNPs with Nd and Yb shell that show sensitive, reversible, and selective optical glucose detection without the need for any surface functionalization or modifications

Engineering of Diamond Based Sensor for Nano-Scale Magnetic Field Sources

Diamond-based magnetometry utilizes the negatively charged nitrogen-vacancy color center NV. For sensing nano-scale magnetic field sources, the small size of the NV is a great advantage over other magnetometers. However, conventional implantation and growth techniques fail to produce very shallow NVs which can be brought to close proximity of small magnetic field sources. Here, we investigate innovative implantation and growth techniques to address this problem. For bulk diamond, we were able to create a concentrated layer of NVs approximately 2nm for the diamond surface. Direct measurement of magnetic sensitivity for this layer yields a sensitivity of 125nT µm³/²∕√ Hz. For currents running in nano-scale wires on the diamond surface this translates to sensitivities below fA/√ Hz. To produce superior nanodiamond magnetic sensor, we attempt growth of fluorescent nanodiamonds using two methods, High-Pressure-High-Temperature (HPHT), and plasma enhanced chemical vapor deposition CVD. We show results for fluorescent nanodiamond grown around 1-adamantylamine seed molecule. We show that the nitrogen in the seed molecule was successfully transformed to NV through electron irradiation at high temperature. Also, we show results of fluorescent nanodiamonds grown using a home built plasma CVD system. Nitrogen was introduced to the diamond by adding trimethylamine to the reactor chamber. Once again, the diamond was not fluorescent until after electron irradiation at high temperature

Fluorescent nanodiamonds: past, present, and future

Multi-color fluorescent nanodiamonds (FNDs) containing a variety of color centers are promising fluorescent markers for biomedical applications. Compared to colloidal quantum dots and organic dyes, FNDs have the advantage of lower toxicity, exceptional chemical stability, and better photostability. They can be surface functionalized by techniques similar to those used for other nanoparticles. They exhibit a variety of emission wavelengths from visible to near infrared, with narrow or broad bandwidths depending on their color centers. In addition, some color centers can detect changes in magnetic fields, electric fields, and temperature. In this article review, we will discuss the current trends in FND’s development, including comparison to the early development of quantum dots. We will also highlight some of the latest advances in fabrication, as well as demonstrations of their use in bioimaging and biosensing.This article is published as Alkahtani, Masfer H., Fahad Alghannam, Linkun Jiang, Abdulrahman Almethen, Arfaan A. Rampersaud, Robert Brick, Carmen L. Gomes, Marlan O. Scully, and Philip R. Hemmer. "Fluorescent nanodiamonds: past, present, and future." Nanophotonics 7, no. 8 (2018): 1423-1453. DOI: 10.1515/nanoph-2018-0025. Posted with permission.</p

Lanthanide ions doped in vanadium oxide for sensitive optical glucose detection

Blood glucose monitoring is essential to avoid the unwanted consequences of glucose level fluctuations. Optical monitors are of special interest because they can be non-invasive. Among optical glucose sensors, fluorescent upconversion nanoparticles (UCNPs) have the advantage of good photostability, low toxicity, and exceptional autofluorescence suppression. However, to sense glucose, UCNPs normally need surface functionalization, and this can be easily affected by other factors in biological systems, and may also affect their ability for real-time sensing of both increasing and decreasing glucose levels. Here, we report YVO4 : Yb3+, Er3+@Nd3+core/shell UCNPs with Nd and Yb shell and GdVO4 : Yb3+, Er3+@Nd3+ core/shell UCNPs with Nd and Yb shell that show sensitive, reversible, and selective optical glucose detection without the need for any surface functionalization or modifications.This article is published as Talib, Ansam J., Masfer Alkahtani, Linkun Jiang, Fahad Alghannam, Robert Brick, Carmen L. Gomes, Marlan O. Scully, Alexei V. Sokolov, and Philip R. Hemmer. "Lanthanide ions doped in vanadium oxide for sensitive optical glucose detection." Optical Materials Express 8, no. 11 (2018): 3277-3287. DOI: 10.1364/OME.8.003277. Posted with permission.</p