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2D graphene oxide (GO) membranes attract great attention because of their ultrathin thickness and superior molecular sieving ability, but their low flux and instability in aqueous environments are still the major challenges for practical applications. In this study, we designed hybrid nanosheets from chemically grafted GO and covalent organic frameworks (COFs) as building blocks to fabricate mixed nanosheet membranes. The covalent triazine framework (CTF), a triazine-based COF, is exfoliated into nanosheets and then reacted with GO to form the GO–CTF hybrid nanosheets, which are then assembled into GO–CTF mixed nanosheet membranes. The GO–CTF membranes show a layered configuration of ca. 32 nm thickness. The incorporation of CTF nanosheets inappreciably changes the interlayer distance of GO–CTF membranes, ensuring high rejections to organic dyes (>90%); meanwhile, the CTF nanosheets afford extra through-plane channels that significantly shorten the water transport pathway. The GO–CTF membranes exhibit a water flux of 226.3 L m–2 h–1 bar–1, more than 12-fold higher than pure GO membranes. Besides, the strong chemical bonds between GO and COF render the GO–CTF membranes notably enhanced stability. Grafting of porous nanosheets onto nonporous nanosheets to acquire hybrid nanosheets as building blocks opens a new avenue to the fabrication of 2D membranes with promising application potential.

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Background: The abrupt rise of colorectal cancer in developing countries is raising concern in healthcare settings. Studies on assessing relationships with modifiable and non-modifiable risk factors in the Pakistani population have been limited. The present investigation was designed to examine associations of dietary practices, addictive behavior and bowel habits in developing colorectal cancer (CRC) among patients in a low-resource setup. Materials and Methods: An age-gender matched case control study was conducted from October 2011 to July 2015 in Karachi, Pakistan. Cases were from the surgical oncology department of a public sector tertiary care hospital, while their two pair-matched controls were recruited from the general population. A structured questionnaire was used which included questions related to demographic characteristics, family history, dietary patterns, addictive behavior and bowel habits. Results: A family history of cancer was associated with a 2.2 fold higher chance of developing CRC. Weight loss reduced the likelihood 7.6 times. Refraining from a high fat diet and consuming more vegetables showed protective effects for CRC. The risk of CRC was more than twice among smokers and those who consumed Asian specific addictive products as compared to those who avoid using these addictions (ORsmoking: 2.12, 95% CI: 1.08 -4.17, ORpan: 2.92, 95% CI: 1.6 -5.33, ORgutka: 2.13, 95% CI: 1.14 -3.97). Use of NSAID attenuated risk of CRC up to 86% (OR: 0.14, 95% CI: 0.07 -0.31). Conclusions: Most of the findings showed concordance with the literature elucidating protective effects of consuming vegetables and low fat diet while documenting adverse associations with family history, weight loss, constipation and hematochezia. Moreover, this study highlighted Asian specific indigenous addictive products as important factors. Further studies are needed to validate the findings produced by this research.

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Mixed matrix membranes (MMMs) have been increasingly utilized in membrane processes. Covalent organic frameworks (COFs) hold great promise as emergent nanofillers to fabricate high-performance MMMs; however, only few studies about COF materials in MMMs have been reported where COFs are all used as nonreactive fillers. Herein, we propose using −NH2-functionalized COF nanosheets as reactive fillers (rCON) to fabricate MMMs. rCON altered the morphology and chemistry of MMMs by controlling the diffusion rate of piperazine through hydrogen bonding prior to the interfacial polymerization process and inducing the creation of ridges in the MMMs with subsequent increase in surface area (∼24%). rCON was chemically cross-linked to the trimesoyl chloride through amide bonding, subsequently elevating the hydrophilicity (∼35%) and fouling resistance of MMMs. The presence of −NH2 groups elevated the rCON–PA compatibility, ensuring the high rCON loading of 5 wt % in the MMMs without sacrificing salt rejection. Accordingly, the PA–rCON MMMs exhibited a flux of 46.5 L m–2 h–1 bar–1, which is 6.8 times higher than that of the pristine PA membrane, with a high rejection rate of 93.5% for Na2SO4.

The linear and nonlinear properties of ion acoustic excitations propagating in warm dense electron-positron-ion plasma are investigated. Electrons and positrons are assumed relativistic and degenerate, following the Fermi-Dirac statistics, whereas the warm ions are described by a set of classical fluid equations. A linear dispersion relation is derived in the linear approximation. Adopting a reductive perturbation method, the Korteweg-de Vries equation is derived, which admits a localized wave solution in the form of a small-amplitude weakly super-acoustic pulse-shaped soliton. The analysis is extended to account for arbitrary amplitude solitary waves, by deriving a pseudoenergy-balance like equation, involving a Sagdeev-type pseudopotential. It is shown that the two approaches agree exactly in the small-amplitude weakly super-acoustic limit. The range of allowed values of the pulse soliton speed (Mach number), wherein solitary waves may exist, is determined. The effects of the key plasma configuration parameters, namely, the electron relativistic degeneracy parameter, the ion (thermal)-to-the electron (Fermi) temperature ratio, and the positron-to-electron density ratio, on the soliton characteristics and existence domain, are studied in detail. Our results aim at elucidating the characteristics of ion acoustic excitations in relativistic degenerate plasmas, e.g., in dense astrophysical objects, where degenerate electrons and positrons may occur.