Ultrathin graphene-based membrane with precise molecular sieving and ultrafast solvent permeation

Graphene oxide (GO) membranes continue to attract intense interest due to their unique molecular sieving properties combined with fast permeation. However, their use is limited to aqueous solutions because GO membranes appear impermeable to organic solvents, a phenomenon not yet fully understood. Here, we report efficient and fast filtration of organic solutions through GO laminates containing smooth two-dimensional (2D) capillaries made from large (10-20 μm) flakes. Without modification of sieving characteristics, these membranes can be made exceptionally thin, down to â 1/410 nm, which translates into fast water and organic solvent permeation. We attribute organic solvent permeation and sieving properties to randomly distributed pinholes interconnected by short graphene channels with a width of 1 nm. With increasing membrane thickness, organic solvent permeation rates decay exponentially but water continues to permeate quickly, in agreement with previous reports. The potential of ultrathin GO laminates for organic solvent nanofiltration is demonstrated by showing >99.9% rejection of small molecular weight organic dyes dissolved in methanol. Our work significantly expands possibilities for the use of GO membranes in purification and filtration technologies

Micropropagation and conservation of selected endangered anticancer medicinal plants from the Western Ghats of India

Globally, cancer is a constant battle which severely affects the human population. The major limitations of the anticancer drugs are the deleterious side effects on the quality of life. Plants play a vital role in curing many diseases with minimal or no side effects. Phytocompounds derived from various medicinal plants serve as the best source of drugs to treat cancer. The global demand for phytomedicines is mostly reached by the medicinal herbs from the tropical nations of the world even though many plant species are threatened with extinction. India is one of the mega diverse countries of the world due to its ecological habitats, latitudinal variation, and diverse climatic range. Western Ghats of India is one of the most important depositories of endemic herbs. It is found along the stretch of south western part of India and constitutes rain forest with more than 4000 diverse medicinal plant species. In recent times, many of these therapeutically valued herbs have become endangered and are being included under the red-listed plant category in this region. Due to a sharp rise in the demand for plant-based products, this rich collection is diminishing at an alarming rate that eventually triggered dangerous to biodiversity. Thus, conservation of the endangered medicinal plants has become a matter of importance. The conservation by using only in situ approaches may not be sufficient enough to safeguard such a huge bio-resource of endangered medicinal plants. Hence, the use of biotechnological methods would be vital to complement the ex vitro protection programs and help to reestablish endangered plant species. In this backdrop, the key tools of biotechnology that could assist plant conservation were developed in terms of in vitro regeneration, seed banking, DNA storage, pollen storage, germplasm storage, gene bank (field gene banking), tissue bank, and cryopreservation. In this chapter, an attempt has been made to critically review major endangered medicinal plants that possess anticancer compounds and their conservation aspects by integrating various biotechnological tool

Decreased Surface Tension of Upper Airway Mucosal Lining Liquid Increases Upper Airway Patency in Anaesthetised Rabbits

The obstructive sleep apnoea syndrome (OSA) is a disorder characterised by repetitive closure and re-opening of the upper airway during sleep. Upper airway luminal patency is influenced by a number of factors including: intraluminal air pressure, upper airway dilator muscle activity, surrounding extraluminal tissue pressure, and also surface forces which can potentially act within the liquid layer lining the upper airway. The aim of the present study was to examine the role of upper airway mucosal lining liquid (UAL) surface tension (γ) in the control of upper airway patency. Upper airway opening (PO) and closing pressures (PC) were measured in 25 adult male, supine, tracheostomised, mechanically ventilated, anaesthetised (sodium pentabarbitone), New Zealand White rabbits before (control) and after instillation of 0.5 ml of either 0.9 % saline (n= 9) or an exogenous surfactant (n= 16; Exosurf Neonatal) into the pharyngeal airway. The γ of UAL (0.2 μl) was quantified using the ‘pull-off’ force technique in which γ is measured as the force required to separate two curved silica discs bridged by the liquid sample. The γ of UAL decreased after instillation of surfactant from 54.1 ± 1.7 mN m−1 (control; mean ±s.e.m.) to 49.2 ± 2.1 mN m−1 (surfactant; P < 0.04). Compared with control, PO increased significantly (P < 0.04; paired t test, n= 9) from 6.2 ± 0.9 to 9.6 ± 1.2 cmH2O with saline, and decreased significantly (P < 0.05, n= 16) from 6.6 ± 0.4 to 5.5 ± 0.6 cmH2O with surfactant instillation. Findings tended to be similar for PC. Change in both PO and PC showed a strong positive correlation with the change in γ of UAL (both r > 0.70, P < 0.001). In conclusion, the patency of the upper airway in rabbits is partially influenced by the γ of UAL. These findings suggest a role for UAL surface properties in the pathophysiology of OSA

Molecular modeling of layered double hydroxide intercalated with benzoate, modeling and experiment

The structure of Zn4Al2 Layered Double Hydroxide intercalated with benzencarboxylate (C6H5COO−) was solved using molecular modeling combined with experiment (X-ray powder diffraction, IR spectroscopy, TG measurements). Molecular modeling revealed the arrangement of guest molecules, layer stacking, water content and water location in the interlayer space of the host structure. Molecular modeling using empirical force field was carried out in Cerius(2) modeling environment. Results of modeling were confronted with experiment that means comparing the calculated and measured diffraction pattern and comparing the calculated water content with the thermogravimetric value. Good agreement has been achieved between calculated and measured basal spacing: d(calc) = 15.3 Å and d(exp) = 15.5 Å. The number of water molecules per formula unit (6H2O per Zn4Al2(OH)12) obtained by modeling (i.e., corresponding to the energy minimum) agrees with the water content estimated by thermogravimetry. The long axis of guest molecules are almost perpendicular to the LDH layers, anchored to the host layers via COO− groups. Mutual orientation of benzoate ring planes in the interlayer space keeps the parquet arrangement. Water molecules are roughly arranged in planes adjacent to host layers together with COO− groups