An Analysis of L2 Stress Patterns of Polysyllabic Academic Vocabulary of Indonesian Students

This research project explores the production of stress placement on polysyllabic academic words of Indonesian students studying at Coventry University, United Kingdom. The research adopts qualitative approach and looks at the accuracy of the stress placement on polysyllabic academic vocabulary produced by the students. The participants of the research are seven Indonesian students studying at Coventry University where they have been studying English for approximately more than ten years. The participants are interviewed and recorded in a silent room in order to obtain a good quality recording. There are three parts of the interview in the research, which consist of free speaking, text-reading and another free speaking about students\u27 opinion. The results are drawn from the recordings by analysing and rating the accuracy of stress placement on the polysyllabic academic words. In addition, it is also rated by a co-rater who is a native speaker and has adequate knowledge on English phonology, to verify the validity and the reliability of the results. The conclusion drawn from the findings is that most participants tend to avoid using academic vocabulary in their presentation based on the first interview and have the tendency of not stressing the words and even misplacing the stress due to ignorance of stress pattern in English. The result indicates that the student\u27s encounter is due to the interference of their mother language as Bahasa is a syllable-timed language meanwhile English is a stress-timed one, which therefore causes significant interference in their stress placement. It is also concluded that the length of exposure of English use in their previous institution can be accountable variable for the accuracy of their stress placement production

Coil-helix transition of polypeptide at water-lipid interface

We present the exact solution of a microscopic statistical mechanical model for the transformation of a long polypeptide between an unstructured coil conformation and an $\alpha$-helix conformation. The polypeptide is assumed to be adsorbed to the interface between a polar and a non-polar environment such as realized by water and the lipid bilayer of a membrane. The interfacial coil-helix transformation is the first stage in the folding process of helical membrane proteins. Depending on the values of model parameters, the conformation changes as a crossover, a discontinuous transition, or a continuous transition with helicity in the role of order parameter. Our model is constructed as a system of statistically interacting quasiparticles that are activated from the helix pseudo-vacuum. The particles represent links between adjacent residues in coil conformation that form a self-avoiding random walk in two dimensions. Explicit results are presented for helicity, entropy, heat capacity, and the average numbers and sizes of both coil and helix segments.Comment: 22 pages, 12 figures, accepted for publication by JSTA

Algorithm for the Analysis of Tryptophan Flourescence Spectra and Their Correlation With Protein Structural Parameters

The fluorescence properties of tryptophan residues are sensitive to the microenvironment of fluorophores in proteins. Therefore, fluorescence characteristics are widely used to study structural transitions in proteins. However, the decoding of the structural information from spectroscopic data is challenging. Here we present a review of approaches developed for the decomposition of multi-component protein tryptophan fluorescence spectra and correlation of these spectral parameters with protein structural properties

Imaging Tumor Acidity: pH-Low Insertion Peptide Probe for Optoacoustic Tomography

Optoacoustic tomography has been used for the detection of pancreatic ductal adenocarcinoma targeted by pH-Low Insertion Peptide (pHLIP) conjugated to near infrared fluorescent dye. It was proved that tumor targeting is a pH-dependent. The approach could have major implication for detection and monitoring of pancreatic and other cancers

Evidence of Inter- and Intra-Molecular Crosslinking of Tyrosine Residues of Calmodulin Induced by Photo-Activation of Ruthenium(II)

Tris(2,2′-bipyridyl)ruthenium(II) upon illumination with light at a wavelength of 450 nm in the presence of an electron acceptor induces dityrosine crosslinking in proteins

The published research paper: is it an important indicator of successful operational research at programme level?

Is a published research paper an important indicator of successful operational research at programme level in low-income countries? In academia, publishing in peer-reviewed scientific journals is highly encouraged and strongly pursued for academic recognition and career progression. In contrast, for those who engage in operational research at programme level, there is often no necessity or reward for publishing the results of research studies; it may even be criticized as being an unnecessary detraction from programme-related work. We present arguments to support publishing operational research from low-income countries; we highlight some of the main reasons for failure of publication at programme level and suggest ways forward

Targeting Diseased Tissues by pHLIP Insertion at Low Cell Surface pH

The discovery of the pH Low Insertion Peptides (pHLIPs®) provides an opportunity to develop imaging and drug delivery agents targeting extracellular acidity. Extracellular acidity is associated with many pathological states, such as those in cancer, ischemic stroke, neurotrauma, infection, lacerations, and others. The metabolism of cells in injured or diseased tissues often results in the acidification of the extracellular environment, so acidosis might be useful as a general marker for the imaging and treatment of diseased states if an effective targeting method can be developed. The molecular mechanism of a pHLIP peptide is based on pH-dependent membrane-associated folding. pHLIPs, being moderately hydrophobic peptides, have high affinities for cellular membranes at normal pH, but fold and insert across membranes at low pH, allowing them to sense pH at the surfaces of cells in diseased tissues, where it is the lowest. Here we discuss the main principles of pHLIP interactions with membrane lipid bilayers at neutral and low pHs, the possibility of tuning the folding and insertion pH by peptide sequence variation, and potential applications of pHLIPs for imaging, therapy and image-guided interventions

pH-sensitive membrane peptides (pHLIPs) as a novel class of delivery agents

Here we review a novel class of delivery vehicles based on pH-sensitive, moderately polar membrane peptides, which we call pH (Low) Insertion Peptides (pHLIPs), that target cells located in the acidic environment found in many diseased tissues, including tumours. Acidity targeting by pHLIPs is achieved as a result of helix formation and transmembrane insertion. In contrast to the earlier technologies based on cell-penetrating peptides, pHLIPs act as monomeric membrane-inserting peptides that translocate one terminus across a membrane into the cytoplasm, while the other terminus remains in the extracellular space, locating the peptide in the membrane lipid bilayer. Therefore pHLIP has a dual delivery capability: it can tether cargo molecules or nanoparticles to the surfaces of cells in diseased tissues and/or it can move a cell-impermeable cargo molecule across the membrane into the cytoplasm. The source of energy for moving polar molecules attached to pHLIP through the hydrophobic layer of a membrane bilayer is the membrane-associated folding of the polypeptide. A drop in pH leads to the protonation of negatively charged residues (Asp or Glu), which enhances peptide hydrophobicity, increasing the affinity of the peptide for the lipid bilayer and triggering peptide folding and subsequent membrane insertion. The process is accompanied by the release of energy that can be utilized to move cell-impermeable cargo across a membrane. That the mechanism is now understood, and that targeting of tumours in mice has been shown, suggest a number of future applications of the pHLIP technology in the diagnosis and treatment of disease