Expression of stathmin in oral squamous cell carcinoma and its correlation with tumour proliferation.

Background: Stathmin is a member of microtubule-associated protein. Inhibition of Stathmin expression can interfere with tumour progression and also alter the sensitivity of tumour cells to microtubule-targeting agents. Thus, it could be a potential therapeutic target for planning new treatment strategies. Objective: To study expression of Stathmin in different histological grades of oral squamous cell carcinoma (OSCC) and its correlation with Ki67 index. Materials and Methods: This study was an observational retrospective and prospective study conducted during a period of two and half years from January 2015 to June 2017 at ESI-PGIMSR Maniktala, Kolkata where 52 cases of OSCC were studied. Haematoxylin and eosin sections were reviewed and representative paraffin blocks were selected. Immunostains were performed using antibody clones for Stathmin and Ki67. For Stathmin scoring, Segersten scoring system was applied. Statistical analysis was done by Graph Pad Prism using Krusher Wallis Test and one-way ANOVA test. Spearman's coefficient was used to establish corelation between Ki 67 and Stathmin overexpression. Results: In this study, it is found that strong Stathmin expression score (4-9) was detected mostly (82.35%) in moderately differentiated (MD) OSCC and poorly differentiated (PD) OSCC (100%), whereas in contrast, 60% of well-differentiated OSCC showed negative-to-weak Stathmin score (1-3). Mean Ki67-labelling index for well-differentiated carcinoma was 32.37%, for moderately differentiated carcinoma was 60.89, and poorly differentiated carcinoma was 86.15%, which demonstrated increased tumour cell proliferation with progression of histological grades of OSCC. Conclusion: Stathmin expression was higher in MD OSCC to PD OSCC compared to well-differentiated carcinoma and its overexpression was significantly correlated with Ki67 index. Thus, Stathmin is overexpressed in higher grades and is correlated with high proliferation of tumour with a potential role as therapeutic target.

Swollen mixed Pluronic surfactant micelles as templates for mesoporous nanotubes with diverse bridged-organosilica frameworks.

Bridged-organosilica nanotubes with a variety of bridging groups (methylene, ethylene, ethenylene, phenylene and p-xylylene) were synthesized using swollen mixtures of Pluronic triblock copolymer surfactants as micellar templates. The mixtures consisted of Pluronic F127 surfactant (EO106PO70EO106) with long poly(ethylene oxide), PEO, blocks, which help prevent the formation of consolidated structures, and another Pluronic with shorter PEO blocks and higher poly(propylene oxide) content, which promote swelling and the cylindrical micelle morphology. In the presence of toluene as a swelling agent, the use of Pluronic P123 (EO20PO70EO20) in the mixture allowed us to readily generate organosilica nanotubes, but the products were often contaminated, sometimes substantially, with large nanospheres and other impurities. On the other hand, the use of Pluronic P104 (EO27PO61EO27) instead of Pluronic P123 typically afforded nanotube products of significant purity. The nanotube morphology was well preserved upon the surfactant removal via extraction or calcination, even though the resulting nanotubes were often more clustered. The nanotubes exhibited high surface areas and uniform inner diameters in the range from ∼12 to 21 nm, depending on the composition and synthesis conditions. Our results indicate that the swollen mixed Pluronic surfactant templates provide an unprecedented access to mesoporous bridged-organosilica nanotubes.

Insights into the Hydrothermal Metastability of Stishovite and Coesite.

Hydrothermal experiments aiming at the crystal growth of stishovite near ambient pressure and temperature were performed in conventional autoclave systems using 1 M (molar) NaOH, 0.8 M Na2CO3, and pure water as a mineralizing agent. It was found that the hydrothermal metastability of stishovite and coesite is very different from the thermal metastability in all mineralizing agents and that because of this fact crystals could not be grown. While stishovite and coesite are thermally metastable up to 500 and >1000 °C, respectively, their hydrothermal metastability is below 150 and 200 °C, respectively. The thermally induced conversion of stishovite and coesite leads to amorphous products, whereas the hydrothermally induced conversion leads to crystalline quartz. Both stishovite and coesite are minerals occurring in nature where they can be exposed to hydrothermal conditions. The low hydrothermal stability of these phases may be an important factor to explain the rarity of these minerals in nature.

Experimental and theoretical investigation of a mesoporous K(x)WO3 material having superior mechanical strength.

Mesoporous materials with tailored properties hold great promise for energy harvesting and industrial applications. We have synthesized a novel tungsten bronze mesoporous material (K(x)WO3; x ∼ 0.07) having inverse FDU-12 type pore symmetry and a crystalline framework. In situ small angle X-ray scattering (SAXS) measurements of the mesoporous K(0.07)WO3 show persistence of a highly ordered meso-scale pore structure to high pressure conditions (∼18.5 GPa) and a material with remarkable mechanical strength despite having ∼35% porosity. Pressure dependent in situ SAXS measurements reveal a bulk modulus κ = 44 ± 4 GPa for the mesoporous K(x)WO3 which is comparable to the corresponding value for the bulk monoclinic WO3 (γ-WO3). Evidence from middle angle (MAXS) and wide angle X-ray scattering (WAXS), high-resolution transmission electron microscopy (HR-TEM) and Raman spectroscopy shows that the presence of potassium leads to the formation of a K-bearing orthorhombic tungsten bronze (OTB) phase within a monoclinic WO3 host structure. Our ab initio molecular dynamics calculations show that the formation of the OTB phase provides superior strength to the mesoporous K(0.07)WO3.

Size tunable synthesis of solution processable diamond nanocrystals.

Diamond nanocrystals were synthesized catalyst-free from nanoporous carbon at high pressure and high temperature (HPHT). The synthesized nanocrystals have tunable diameters between 50 and 200 nm. The nanocrystals are dispersible in organic solvents such as acetone and are isotropic in nature as seen by dynamic light scattering.

Synthetic chemistry with periodic mesostructures at high pressure.

Over the last two decades, researchers have studied extensively the synthesis of mesostructured materials, which could be useful for drug delivery, catalytic cracking of petroleum, or reinforced plastics, among other applications. However, until very recently researchers used only temperature as a thermodynamic variable for synthesis, completely neglecting pressure. In this Account, we show how pressure can affect the synthetic chemistry of periodic mesoporous structures with desirable effects. In its simplest application, pressure can crystallize the pore walls of periodic mesoporous silicas, which are difficult to crystallize otherwise. The motivation for the synthesis of periodic mesoporous silica materials (with pore sizes from 2 to 50 nm) 20 years ago was to replace the microporous zeolites (which have pore sizes of <2 nm) in petroleum cracking applications, because the larger pore size of mesoporous materials allows for faster transport of larger molecules. However, these mesoporous materials could not replace zeolite materials because they showed lower hydrothermal stability and lower catalytic activity. This reduced performance has been attributed to the amorphous nature of the mesoporous materials' channel walls. To address this problem, we developed the concept of "nanocasting at high pressure". Through this approach, we produced hitherto-unavailable, periodic mesostructured silicas with crystalline pore walls. In nanocasting, we compress a periodic mesostructured composite (e.g. a periodic mesoporous silica with carbon-filled pores) and subsequently heat it to induce the selective crystallization of one of the two phases. We attain the necessary high pressure for synthesis using piston-cylinder and multianvil apparatuses. Using periodic mesostructured silica/carbon nanocomposites as starting material, we have produced periodic mesoporous coesite and periodic mesoporous quartz. The quartz material is highly stable under harsh hydrothermal conditions (800°C in pure steam), verifying that crystallinity in the channel walls of periodic mesoporous silicas increases their hydrothermal stability. Even without including the carbon phase in the silica pores, we could obtain mesoporous coesite materials. We found similar behavior for periodic mesoporous carbons, which convert into transparent, mesoporous, nanopolycrystalline diamond at high-pressure. We also show that periodic mesoporous materials can serve as precursors for nanocrystals of high-pressure phases. We obtained nearly monodisperse, discrete stishovite nanocrystals from periodic mesoporous silicas and coesite nanocrystals from periodic mesoporous organosilicas. The stishovite nanocrystals disperse in water and form colloidal solutions of individual stishovite nanocrystals. The stishovite nanocrystals could be useful for machining, drilling, and polishing. Overall, the results show that periodic mesoporous materials are suitable starting materials for the synthesis of nanoporous high-pressure phases and nanocrystals of high pressure phases. The substantially enhanced hydrothermal stability seen in periodic mesoporous silicas synthesized at high pressure demonstrates that high pressure can be a useful tool to produce porous materials with improved properties. We expect that synthesis using mesostructures at high pressure can be extended to many other materials beyond silicas and carbons. Presumably, this chemistry can also be extended from mesoporous to microporous and macroporous materials.

Face-centered-cubic large-pore periodic mesoporous organosilicas with unsaturated and aromatic bridging groups.

Large-pore ethenylene-bridged (-CH═CH-) and phenylene-bridged (-C(6)H(4)-) periodic mesoporous organosilicas (PMOs) with face-centered-cubic structure (Fm3m symmetry) of spherical mesopores were synthesized at 7 °C at low acid concentration (0.1 M HCl) using Pluronic F127 triblock copolymer surfactant in the presence of aromatic swelling agents (1,3,5-trimethylbenzene, xylenes-isomer mixture, and toluene). In particular, this work reports an unprecedented block-copolymer-templated well-ordered ethenylene-bridged PMO with cubic structure of spherical mesopores and an unprecedented block-copolymer-templated face-centered cubic phenylene-bridged PMO, which also has an exceptionally large unit-cell size and pore diameter. The unit-cell parameters of 30 and 25 nm and the mesopore diameters of 14 and 11 nm (nominal BJH-KJS pore diameters of 12-13 and 9 nm) were obtained for ethenylene-bridged and phenylene-bridged PMOs, respectively. Under the considered reaction conditions, the unit-cell parameters and pore diameters were found to be similar when the three different methyl-substituted benzene swelling agents were employed, although the degree of structural ordering appeared to improve for phenylene-bridged PMOs in the sequence of decreased number of methyl groups on the benzene ring.