Application and evaluation of Tip Enhanced Raman Spectroscopy in pharmaceutical analysis

Pharmaceutical analysis plays a crucial role in drug manufacturing, allowing the identification and exploration of the physio-chemical properties and interactions between active pharmaceutical ingredients (API) and excipients within a formulation. However, conventional microscopy instruments can be constrained in resolving chemical information below the micron-length scales. A newly arising nano-analytical technique is the Tip-Enhanced Raman Spectroscopy (TERS), which can obtain valuable spatio-chemical information from the sample of interest, at the length scales of tens of nanometres or less. TERS application has been reported on numerous carbon-based and biological samples, however to-date there are no records of TERS application on pharmaceutical formulations. This thesis evaluates the application of TERS technique on individual pharmaceutical components or amorphous solid dispersions (ASDs). These include paracetamol, felodipine, nicotinamide, copovidone, polyvinyl alcohol (PVA) either alone or in combination as well as di-phenylalanine tubes. In these studies two microscopy systems were used to examine the samples of interest. One is the custom-built combined Atomic Force Microscopy - Confocal Raman Microscopy (AFM-CRM) system (located at the School of Physics and Astronomy - Chapter 2), equipped with silicon AFM probes and the second is the TERS system which is a combined AFM-CRM instrument of similar specifications (located at the National Physical Laboratory), equipped with Ag-coated TERS probes. Under the TERS equipment di-phenylalanine tubes were tested to evaluate the degree of signal enhancement and spatial resolution which can be obtained, followed by spectral evaluation of the ASDs, namely paracetamol/copovidone 50% w/w and felodipine/copovidone 50% w/w, in Ag-coated probe retracted and engaged positions (Chapter 3). With the intense photoluminescence background noise generated from the spectra in engaged probe position, two further studies were performed to identify the potential causes in individual pharmaceutical components (Chapters 4 and 5). In Chapter 4, each tested component was exposed under prolonged laser irradiation, with the AFM-CRM instrument, finding the threshold of sample photodegradation alongside with the association of photoluminescence occurrence in temperature rise. Moreover in Chapter 5, multiple spectra were acquired under the TERS instrument as a function to apex-to-focal spot distance across the XYZ directions, recording any changes in the spectra, including signal enhancement and sample photodegradation. After identifying paracetamol’s properties to withstand prolounged laser irradiation and provide adequate signal enhancement, AFM, CRM and TERS maps were obtained from both systems (Chapter 6). Specifically, paracetamol/PVA 30% w/w 2D-printed microdot was interrogated under the probe, detecting nano-meter length inhomogeneities at the sample surface. Under the tested bottom-illumination TERS instrument equipped with 532 nm incident light, most pharmaceutical components and formulations showed low TERS signal enhancement. In all studies, felodipine displayed photodegradation, whereas paracetamol demonstrated small enhancement beneath the probe apex. With limited signal enhancement, it was feasible to demonstrate qualitatively ASD inhomogeneity at the surface of the formulation

Power consumption analysis on an IoT network based on wemos: a case study

On Internet of Things network (IoT), connections established among every device that connected to the Internet. An IoT uses different communication method instead to that, the Internet uses. Internet of Things (IoT) applications, use a light weight protocol Message Queue Telemetry Transport (MQTT). In this article an Internet of Things (IoT) system is presented, an advanced solution of monitoring the temperature and luminosity at different locations in a data centre of MQTT Server, measuring power consumption in 2 types of time of capturing data (every 0,5 min and every 1 min) making temperature and luminosity data visible over internet through cloud based dashboard. The quality of service (QoS) in some application is very crucial because the data collection is essential. This research focus on QoS in terms of power consumption as well as the battery life of the system. The results show that the battery life span is proportional to the QoS and the longevity of the battery and respectively the IoT network life depends on it

Harmonic organisation conveys both universal and culture-specific cues for emotional expression in music

Previous research conducted on the cross-cultural perception of music and its emotional content has established that emotions can be communicated across cultures at least on a rudimentary level. Here, we report a cross-cultural study with participants originating from two tribes in northwest Pakistan (Khow and Kalash) and the United Kingdom, with both groups being naïve to the music of the other respective culture. We explored how participants assessed emotional connotations of various Western and non-Western harmonisation styles, and whether cultural familiarity with a harmonic idiom such as major and minor mode would consistently relate to emotion communication. The results indicate that Western concepts of harmony are not relevant for participants unexposed to Western music when other emotional cues (tempo, pitch height, articulation, timbre) are kept relatively constant. At the same time, harmonic style alone has the ability to colour the emotional expression in music if it taps the appropriate cultural connotations. The preference for one harmonisation style over another, including the major-happy/minor-sad distinction, is influenced by culture. Finally, our findings suggest that although differences emerge across different harmonisation styles, acoustic roughness influences the expression of emotion in similar ways across cultures; preference for consonance however seems to be dependent on cultural familiarity

Indications and Techniques of Endoscope Assisted Vitrectomy

The popularization of ophthalmic endoscopy has been promoted by recent technological advancements that increase the number of indications for endoscopy. These advancements have improved the endoscope’s capabilities in its two fundamental surgical advantages: (1) bypassing anterior segment opacities, and (2) visualizing anteriorly positioned structures such as the ciliary bodies and sub-iris space. In this article, the current state of the ophthalmic endoscope is reviewed alongside its growing number of applications in glaucoma, vitreoretinal, and ocular trauma surgery. We describe the role of endoscopy in endocyclophotocoagulation for glaucoma, cyclitic membrane peeling in hypotony, retinal detachment surgery, intraocular foreign body removal, severe endophthalmitis, and pediatric traumatic vitreoretinal surgery. This review examines both the pearls and limitations of the ophthalmic application of endoscopy. In doing so, we hope to provide guidelines for using the endoscope and also to highlight applications of endoscopy that merit further study

Surface plasmon toy-model of a rotating black hole

Recently introduced surface plasmon toy black hole model has been extended in order to emulate a rotating black hole (Kerr metric). Physical realization of this model involves a droplet of an optically active liquid on the metal surface which supports propagation of surface plasmons. Such droplets are shown to exhibit giant optical activity in the frequency range near the surface plasmon resonance of a metal-liquid interface.Comment: 4 pages, 4 figure

A hybrid framework for nonlinear dynamic simulations including full-field optical measurements and image decomposition algorithms

Innovative designs of transport vehicles need to be validated in order to demonstrate reliability and provide confidence. It is normal practice to study the mechanical response of the structural elements by comparing numerical results obtained from finite element simulation models with results obtained from experiment. In this frame, the use of wholefield optical techniques has been proven successful in the validation of deformation, strain, or vibration modes. The strength of full-field optical techniques is that the entire displacement field can be acquired. The objective of this article is to integrate full-field optical measurement methodologies with state-of-the-art computational simulation techniques for nonlinear transient dynamic events. In this frame, composite car bonnet frame structures of dimensions about 1.8 m 30.8 m are considered. They have been tested in low-velocity mass-drop impact loading with impact energies ranging from 20 to 200 J. In parallel, simulation models of the car bonnet frame have been developed using layered shell elements. The Zernike shape descriptor approach was used to decompose numerical and experimental data into moments for comparison purposes. A very good agreement between numerical and experimental results was observed. Therefore, integration of numerical analysis with full-field optical measurements along with sophisticated comparison techniques can increase design reliability