The conformation of molecules, peptides, and proteins, self-assembled into structured monolayers on the surface of metal nanoparticles (NPs), can strongly affect their properties and use in chemical ...or nanobiomedical applications. Elucidating molecular conformations on the NP surface is highly challenging, and the microscopic details mostly remain elusive. Using polarization-selective third-order two-dimensional ultrafast infrared spectroscopy, we revealed the highly ordered intermolecular structure of γ-tripeptide glutathione on the surface of silver NPs in aqueous solution. Glutathione is an antioxidant thiol abundant in living cells; it is extensively used in NP chemistry and related research. We identified conditions where the interaction of glutathione with the NP surface facilitates formation of a β-sheet-like structure enclosing the NPs. A spectroscopic signature associated with the assembly of β-sheets into an amyloid fibril-like structure was also observed. Remarkably, the interaction with the metal surface promotes formation of a fibril-like structure by a small peptide involving only two amino acids.
The flexibility of 2D materials combined with properties highly sensitive to strain makes strain engineering a promising avenue for manipulation of both structure and function. Here we investigate ...the influence of strain, associated with microstructural defects, on a photo-induced structural phase transition in Td-WTe
2
. Above threshold photoexcitation of uniform, non-strained, samples result in an orthorhombic Td to a metastable orthorhombic 1T* phase transition facilitated by shear displacements of the WTe
2
layers along the
b
axis of the material. In samples prepared with wrinkle defects WTe
2
continue its trajectory through a secondary transition that shears the unit cell along the
c
axis towards a metastable monoclinic 1T′ phase. The time scales and microstructural evolution associated with the transition and its subsequent recovery to the 1T* phase is followed in detail by a combination of ultrafast electron diffraction and microscopy. Our findings show how local strain fields can be employed for tailoring phase change dynamics in ultrafast optically driven processes with potential applications in phase change devices.
The flexibility of 2D materials combined with properties highly sensitive to strain makes strain engineering a promising avenue for manipulation of both structure and function.
Elevating Akt activation is an obvious clinical strategy to prevent progressive neuronal death in neurological diseases. However, this endeavor has been hindered because of the lack of specific Akt ...activators. Here, from a cell-based high-throughput chemical genetic screening, we identified a small molecule SC79 that inhibits Akt membrane translocation, but paradoxically activates Akt in the cytosol. SC79 specifically binds to the PH domain of Akt. SC79-bound Akt adopts a conformation favorable for phosphorylation by upstream protein kinases. In a hippocampal neuronal culture system and a mouse model for ischemic stroke, the cytosolic activation of Akt by SC79 is sufficient to recapitulate the primary cellular function of Akt signaling, resulting in augmented neuronal survival. Thus, SC79 is a unique specific Akt activator that may be used to enhance Akt activity in various physiological and pathological conditions.
Science and Technology Studies (STS) by the very act of showing the multiplicity, contingency, and context-dependence of scientific knowledge and practice, provincialized modern science. Postcolonial ...interventions within STS have pursued this goal even further. Nevertheless, Euro/West-centrism continues to inflect not only scientific practices and lay imaginaries, but also sociological and historical analyses of sciences. In this article, drawing on my own training within STS – first under J.P.S. Uberoi, who was concerned with structuralist analysis of modernity and science, and thereafter under Andy Pickering, when we focused on material agency and temporal emergence and extensively engaged with Actor Network Theory - I emphasize the continuing role of Euro/West-centric discourses in defining the “self” and the “other” and in impacting epistemological and ontological interventions. More broadly, building on a concept of Michael Lynch’s, I call for excavation and analysis of discursive contextures of sciences. In the second section of the article, through a brief analysis of embryonic stem cell therapy in a clinic in Delhi, I show how with shifting transnational landscape of technoscience certain discursive contextures are being “deterritorialized” and left “stuttering.”
TiO
2
colloidal nanoparticles and nanocrystals are prepared by hydrolysis of titanium isopropoxide employing a surfactant-free synthetic hydrothermal method. The synthesized samples are characterized ...by X-ray diffraction (XRD), HRTEM and FTIR. The XRD study confirms that the size of the colloidal nanoparticle is around 4 nm which the HRTEM analysis indicates the sizes of the colloidal nanoparticles are in the range of 2.5 nm. The fluorescence property of the TiO
2
colloidal nanoparticles studied by the emission spectrum confirms the presence of defect levels caused by the oxygen vacancies. We have observed new emission bands at 387 nm,421 nm, 485 nm, 530 nm and 574 nm wavelengths, first one (387 nm) being emission due to annihilation of excitons while remaining four could be arising from surface states. The emission spectrum of annealed nanocrystallites is also having these four band emissions. It is observed that the surface state emission basically consists of two categories of emission.
COVID–19 has not only resulted in nearly two and a half million deaths globally but it has also spawned a pandemic of misinformation and conspiracies. In this article I examine COVID–19 ...misinformation and conspiracies in the United States (US). These misinformation and conspiracies have been commonly argued to be anti-science. I argue, although it is important to rebut false information and stop their spread, social scientists need to analyse how such anti-science claims are discursively framed and interpreted. Specifically, I show how the framing of the anti-science conspiracies utilise the credibility of science and scientists. I also explore how the COVID–19 misinformation and conspiracies were given different meaning among different social groups. The article is divided into three sections. In the first section I analyse the discursive emplotment of the Plandemic video that had Dr Judy Mikovits presenting several COVID–19 conspiracy theories and went viral before it was taken down from major social media platforms. I show how the video draws on the credibility of science, scientists, and scientific journals to present misinformation and conspiracies claims against vaccination, mask wearing, etc. The second section explores how COVID–19 misinformation and conspiracies were interpreted among the African-American community by drawing on the history of black community’s experiences in the US and as such how their interpretations stand in contrast to the interpretations of the COVID–19 misinformation and conspiracies among the White community. The last section analyses the role of STS in engaging with anti-science and post-truth issues and emphasises the need to excavate genealogies of the present even with regard to misinformation and conspiracies.
Cells regularly synthesize new proteins to replace old or damaged proteins. Deposition of various aberrant proteins in specific brain regions leads to neurodegeneration and aging. The cellular ...protein quality control system develop various defense mechanisms against the accumulation of misfolded and aggregated proteins. The mechanisms underlying the selective recognition of specific crucial protein or misfolded proteins are majorly governed by quality control E3 ubiquitin ligases mediated through ubiquitin-proteasome system. Few known E3 ubiquitin ligases have shown prominent neurodevelopmental functions, but their interactions with different developmental proteins play critical roles in neurodevelopmental disorders. Several questions are yet to be understood properly. How E3 ubiquitin ligases determine the specificity and regulate degradation of a particular substrate involved in neuronal proliferation and differentiation is certainly the one, which needs detailed investigations. Another important question is how neurodevelopmental E3 ubiquitin ligases specifically differentiate between their versatile range of substrates and timing of their functional modulations during different phases of development. The premise of this article is to understand how few E3 ubiquitin ligases sense major molecular events, which are crucial for human brain development from its early embryonic stages to throughout adolescence period. A better understanding of these few E3 ubiquitin ligases and their interactions with other potential proteins will provide invaluable insight into disease mechanisms to approach toward therapeutic interventions.
Major cause of proteopathies is the accumulation of unwanted mutant and aberrant proteins. We know that imperfect ageing is one of chief risk factor for most neurodegenerative diseases. ...Neurodegenerative diseases are characterized by mutant misfolded protein aggregates developing neural stress and debilitating several neuronal processes. Reducing the levels of these abnormal proteins using various natural compounds can be a promising possible therapeutic strategy. But the advancement of natural compound-based therapies in neurodegeneration and imperfect ageing treatment has been impeded by different challenges and unknown molecular patho-mechansim. The complexity in the causative factors generating protein aggregates in neurons and their respective path towards cell death is high, making it a difficult to treat disorder. Several plant based compounds have proven to promote different neuronal homeostasis mechanisms. However, there is a pressing necessity to screen, find and develop cost-effective natural compound-based new therapeutic interventions which can be useful for clinical purposes in treating neurodegenerative ailments. It is critical to discuss and elaborate the applications of few important natural compounds and their connections with following mechanisms: protein disposal machineries, apoptosis, neuroinflammation, neuronal development, synaptogenesis and neural homeostasis. This article summarizes the current knowledge and discusses the unanswered questions linked with the natural compounds and their promising therapeutic avenues primarily focusing on neurodegenerative diseases and defective neurobiological mechanisms.
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