Membranes for olefin-paraffin separation: An industrial perspective.

In the next decade, separation science will be an important research topic in addressing complex challenges like reducing carbon footprint, lowering energy cost, and making industrial processes simpler. In industrial chemical processes, particularly in petrochemical operations, separation and product refining steps are responsible for up to 30% of energy use and 30% of the capital cost. Membranes and adsorption technologies are being actively studied as alternative and partial replacement opportunities for the state-of-the-art cryogenic distillation systems. This paper provides an industrial perspective on the application of membranes in industrial petrochemical cracker operations. A gas separation performance figure of merit for propylene/propane separation for different classes of materials ranging from inorganic, carbon, polymeric, and facilitated transport membranes is also reported. An in-house-developed model provided insights into the importance of operational parameters on the overall membrane design.

Directing Traffic: Halogen-Bond-Mediated Membrane Transport.

The plasma membrane regulates the transport of molecules into the cell. Small hydrophobic molecules can diffuse directly across the lipid bilayer. However, larger molecules require specific transporters for their entry into the cell. Regulating the cellular entry of small molecules and proteins is a challenging task. The introduction of halogen, particularly iodine, to small molecules and proteins is emerging to be a promising strategy to improve the cellular uptake. Recent studies reveal that a simple substitution of hydrogen atom with iodine not only increases the cellular uptake, but also regulates the membrane transport. The strong halogen-bond-forming ability of iodine atoms plays a crucial role in the transport and the introduction of iodine may provide an efficient strategy for studying membrane activity and cellular functions and improving the delivery of therapeutic agents. This Concept article does not provide a comprehensive picture of membrane transport but highlights halogen-substitution as a novel strategy for understanding and regulating the cell-membrane traffic.

A Single Atom Change Facilitates the Membrane Transport of Green Fluorescent Proteins in Mammalian Cells.

Direct delivery of proteins into mammalian cells is a challenging problem in biological and biomedical applications. The most common strategies for the delivery of proteins into the cells include the use of cell-penetrating peptides or supercharged proteins. Herein, we show for the first time that a single atom change, hydrogen to halogen, at one of the tyrosine residues can increase the cellular entry of ∼28 kDa green fluorescent protein (GFP) in mammalian cells. The protein uptake is facilitated by a receptor-mediated endocytosis and the cargo can be released effectively into cytosol by co-treatment with the endosomolytic peptide ppTG21.

Rightsizing Nanochannels in Reduced Graphene Oxide Membranes by Solvating for Dye Desalination.

Membranes with high water permeance, near-zero rejection to inorganic salts (such as NaCl and Na2SO4), and almost 100% rejection to organic dyes are of great interest for the dye desalination (the separation of dyes and salts) of textile wastewater. Herein, we prepared reduced graphene oxide membranes in a solvation state (S-rGO) with nanochannel sizes rightly between the salt ions and dye molecules. The S-rGO membrane rejects >99.0% of Direct Red 80 (DR 80) and has almost zero rejection for Na2SO4. By contrast, conventional GO or rGO membranes often have channel sizes smaller than divalent ions (such as SO42-) and thus high rejection for Na2SO4. More interestingly, high salinity in typical dye solutions decreases the channel size in the S-rGO membranes and thus increases the dye rejection, while the Na2SO4 rejection decreases because of the negatively charged surface on GO and the salt screening effect. The membranes also show pure water permeance as high as 80 L m-2 h-1 bar-1, which is about 8 times that of commercial NF 90 membrane and 2 times that of a commercial ultrafiltration membrane (with a molecular weight cutoff of 2000 Da), rendering their promise for practical dye desalination.

Blunt Trauma Neck with Complete Tracheal Transection - A Diagnostic and Therapeutic Challenge to the Trauma Team.

Survival following trachea-esophageal transection is uncommon. Establishing a secure airway has the highest priority in trauma management. Airway management is a unique and a defining element to the specialty of emergency medicine. There is no doubt regarding the significance of establishing a patent airway in the critically ill patient in the emergency department. Cannot intubate and cannot ventilate situation is a nightmare to all emergency physicians. The most important take-home message from this case report is that every Emergency physician should have the ability to predict "difficult airway" and recognize "failed airway" very early and be skilled in performing rescue techniques when routine oral-tracheal intubation fails. Any delay at any step in the "failed airway" management algorithm may not save the critically ill dying patient. Here, we report a case of blunt trauma following high-velocity road traffic accident, presenting in the peri-arrest state, in whom we noticed "failed airway" which turned out to be due to complete tracheal transection. In our patient, although we had secured the airway immediately, he had already sustained hypoxic brain damage. This scenario emphasizes the importance of prehospital care in developing countries.

Anticancer activity of rice callus suspension culture.

A multitude of natural products from plant extracts have been tested for their ability to inhibit the progression of several diseases including cancer. A novel approach of evaluating plant (rice) callus suspension cultures for anticancer activity is reported. The ability of different dilutions of rice callus suspension cultures to inhibit growth of two human cancer cell lines was tested employing varying cell numbers and different incubation times. A crystal violet assay was performed to assess cell viability of the cancer cell lines. Furthermore, microscopic analysis was carried out to determine the effect of the rice callus culture on the morphology of the cancer cells. Rice callus suspension cultures significantly inhibited the growth of human cancer and renal cell lines at densities of 5000 and 10000 cells/mL when incubated for 72 and 96 h. Rice callus suspension culture was more efficient than paclitaxel (Taxol®) and etoposide in selectively killing human colon and renal cancer cell lines compared with a control cell line (human lung fibroblasts). The use of plant callus suspension cultures is a novel approach for inhibiting the growth of cancer cells, which will lead to the development of new agents for selectively killing cancer cells.

Amino-functionalized SAPO-34 membranes for CO2/CH4 and CO2/N2 separation.

SAPO-34 seeds and membranes were functionalized with several organic amino cations, such as ethylenediamine, hexylamine, and octylamine. The successful incorporation of the amino groups in the SAPO-34 framework was confirmed by Fourier transform infrared (FTIR) and X-ray photoemission (XPS) spectroscopies. The resultant SAPO-34 membranes were evaluated for the separation of CO2/CH4 and CO2/N2 gas mixtures. CO2/CH4 selectivities as high as 245, with CO2 permeances of ∼5 × 10(-7) mol m(-2) s(-1) Pa(-1) at 295K and 138 kPa, were observed for an optimum ethylenediamine-functionalized membrane, which corresponded to a ∼40% increase in the separation index, as compared to the nonfunctionalized SAPO-34 membrane. Similarly, the CO2/N2 separation performance was highly improved with the incorporation of ethylenediamine. CO2/N2 selectivities as high as 39, with CO2 permeances of ∼2.1 × 10(-7) mol m(-2) s(-1) Pa(-1) at 295K and 138 kPa, were observed for an optimum ethylenediamine-functionalized membrane, which corresponded to a ∼167% increase in the separation index, as compared to the nonfunctionalized SAPO-34 membrane.

Mechanistic investigations on the efficient catalytic decomposition of peroxynitrite by ebselen analogues.

In this study, ebselen and its analogues are shown to be catalysts for the decomposition of peroxynitrite (PN). This study suggests that the PN-scavenging ability of selenenyl amides can be enhanced by a suitable substitution at the phenyl ring in ebselen. Detailed mechanistic studies on the reactivity of ebselen and its analogues towards PN reveal that these compounds react directly with PN to generate highly unstable selenoxides that undergo a rapid hydrolysis to produce the corresponding seleninic acids. The selenoxides interact with nitrite more effectively than the corresponding seleninic acids to produce nitrate with the regeneration of the selenenyl amides. Therefore, the amount of nitrate formed in the reactions mainly depends on the stability of the selenoxides. Interestingly, substitution of an oxazoline moiety on the phenyl ring stabilizes the selenoxide, and therefore, enhances the isomerization of PN to nitrate.

Scalable Polymeric Few-Nanometer Organosilica Membranes with Hydrothermal Stability for Selective Hydrogen Separation.

Nanoporous silica membranes exhibit excellent H2/CO2 separation properties for sustainable H2 production and CO2 capture but are prepared via complicated thermal processes above 400 °C, which prevent their scalable production at a low cost. Here, we demonstrate the rapid fabrication (within 2 min) of ultrathin silica-like membranes (∼3 nm) via an oxygen plasma treatment of polydimethylsiloxane-based thin-film composite membranes at 20 °C. The resulting organosilica membranes unexpectedly exhibit H2 permeance of 280-930 GPU (1 GPU = 3.347 × 10-10 mol m-2 s-1 Pa-1) and H2/CO2 selectivity of 93-32 at 200 °C, far surpassing state-of-the-art membranes and Robeson's upper bound for H2/CO2 separation. When challenged with a 3 d simulated syngas test containing water vapor at 200 °C and a 340 d stability test, the membrane shows durable separation performance and excellent hydrothermal stability. The robust H2/CO2 separation properties coupled with excellent scalability demonstrate the great potential of these organosilica membranes for economic H2 production with minimal carbon emissions.

A multiparametric extraction method for Vn96-isolated plasma extracellular vesicles and cell-free DNA that enables multi-omic profiling.

Extracellular vesicles (EVs) have been recognized as a rich material for the analysis of DNA, RNA, and protein biomarkers. A remaining challenge for the deployment of EV-based diagnostic and prognostic assays in liquid biopsy testing is the development of an EV isolation method that is amenable to a clinical diagnostic lab setting and is compatible with multiple types of biomarker analyses. We have previously designed a synthetic peptide, known as Vn96 (ME kit), which efficiently isolates EVs from multiple biofluids in a short timeframe without the use of specialized lab equipment. Moreover, it has recently been shown that Vn96 also facilitates the co-isolation of cell-free DNA (cfDNA) along with EVs. Herein we describe an optimized method for Vn96 affinity-based EV and cfDNA isolation from plasma samples and have developed a multiparametric extraction protocol for the sequential isolation of DNA, RNA, and protein from the same plasma EV and cfDNA sample. We are able to isolate sufficient material by the multiparametric extraction protocol for use in downstream analyses, including ddPCR (DNA) and 'omic profiling by both small RNA sequencing (RNA) and mass spectrometry (protein), from a minimum volume (4 mL) of plasma. This multiparametric extraction protocol should improve the ability to analyse multiple biomarker materials (DNA, RNA and protein) from the same limited starting material, which may improve the sensitivity and specificity of liquid biopsy tests that exploit EV-based and cfDNA biomarkers for disease detection and monitoring.

Highly permeable zeolite imidazolate framework-8 membranes for CO2/CH4 separation.

ZIF-8 membranes, a type of zeolite imidazolate framework, were synthesized by secondary seeded growth on tubular alpha-Al(2)O(3) porous supports. The presence of small, highly crystalline, microporous crystals with narrow particle size distribution led to continuous thin membranes. The synthesized novel ZIF-8 membranes displayed unprecedented high CO(2) permeances and relatively high separation indexes for equimolar mixtures of CO(2) and CH(4).

Structural evolution of zeolitic imidazolate framework-8.

We report the structural evolution of zeolitic imidazolate framework-8 (ZIF-8) as a function of time at room temperature. We have identified the different stages of ZIF-8 formation (nucleation, crystallization, growth, and stationary periods) and elucidated its kinetics of transformation. We hypothesize that the observed semicrystalline-to-crystalline transformation may take place via solution- and solid-mediated mechanisms, as suggested by the observed phase transformation evolution and Avrami's kinetics, respectively. A fundamental understanding of ZIF-8 structural evolution as demonstrated in this study should facilitate the preparation of functional metal-organic framework phases with controlled crystal size and extent of crystallinity.

Synthesis of SAPO-34 crystals in the presence of crystal growth inhibitors.

Microporous SAPO-34 molecular sieves were synthesized employing polyethylene glycol, polyoxyethylene lauryl ether, and methylene blue as crystal growth inhibitors. The synthesized SAPO-34 crystals displayed BET surface areas up to 700 m2/g, high CO2/CH4 adsorption ratios, and small crystal size in the approximately 0.6-0.9 microm range with narrow particle size distribution. The enhanced CO2/CH4 adsorption capacities were related to the high N/H ratios observed in the phases prepared in the presence of crystal growth inhibitors. The synthesized SAPO-34 crystals may find potential applications to prepare membranes for CO2 purification.

Wild tuber poisoning: Arum maculatum - A rare case report.

Arum maculatum, commonly known as wild Arum, is a woodland plant species of the Araceae family. All parts of this plant are considered toxic. We report a case of a young man who allegedly consumed poisonous wild tuber with suicidal intention. He presented to our emergency department 3 h later with features of angioedema. He was managed successfully with adrenaline and hydrocortisone. He was discharged after 4 days of observation. Later, the wild tuber plant was identified to be A. maculatum. We recommend that all patients who present with unknown substance poisoning should be managed according to the principles of intensive care, irrespective of the diagnosis.

Simple Fabrication Method for Mixed Matrix Membranes with in Situ MOF Growth for Gas Separation.

Metal organic framework (MOF)/polymer composite membranes are of interest for gas separations, as they often have performance that exceeds the neat polymer. However, traditional composite membranes, known as mixed matrix membranes (MMMs), can have complex and time-consuming preparation procedures. The MOF and polymer are traditionally prepared separately and require priming and mixing to ensure uniform distribution of particles and compatibility of the polymer-particle interface. In this study, we reduce the number of steps using an in situ MOF growth strategy. Herein, MMMs are prepared by growing MOF (UiO-66) in situ within a Matrimid polymer matrix while simultaneously curing the matrix. The gas separation performance for MMMs, prepared using this approach, was evaluated for the CO2/N2 separation and compared with MMMs made using the traditional postsynthesis mixing. It was found that MMMs prepared using both the in situ MOF growth strategy and by traditional postsynthesis mixing are equivalent in performance. However, using the in situ MOF growth allows for a simpler, faster, and potentially more economical fabrication alternative for MMMs.

siRNA Delivery Using a Cationic-Lipid-Based Highly Selective Human DNA Ligase I Inhibitor.

The present article illustrates the serendipitous discovery of a cationic-lipid-based human DNA ligase (hLig) I inhibitor and the development of siRNA delivering, a hLigI-targeted cationic-lipid-based nonviral vector. We have tested a small in-house library of structurally similar cationic lipo-anisamides for antiligase activity, and amongst tested, N-dodecyl-N-(2-(4-methoxybenzamido)ethyl)-N-methyldodecan-1-ammonium iodide (C12M) selectively and efficiently inhibited the enzyme activity of hLigI, compared to other human ligases (hLigIIIß and hLigIV/XRCC4) and bacterial T4 DNA ligase. Furthermore, upon hydration with equimolar cholesterol, C12M produced antiligase cationic liposomes, which transfected survivin siRNA and showed significant inhibition of tumor growth.

Continuous Flow Processing of ZIF-8 Membranes on Polymeric Porous Hollow Fiber Supports for CO2 Capture.

We have utilized an environmentally friendly synthesis approach for the accelerated growth of a selective inorganic membrane on a polymeric hollow fiber support for postcombustion carbon capture. Specifically, continuous defect-free ZIF-8 thin films were grown and anchored using continuous flow synthesis on the outer surface of porous supports using water as solvent. These membranes demonstrated CO2 permeance of 22 GPU and the highest reported CO2/N2 selectivity of 52 for a continuous flow synthesized ZIF-8 membrane.

Separation of carbon dioxide from flue gas by mixed matrix membranes using dual phase microporous polymeric constituents.

This study presents the fabrication of a new mixed matrix membrane using two microporous polymers: a polymer of intrinsic microporosity PIM-1 and a benzimidazole linked polymer, BILP-101, and their CO2 separation properties from post-combustion flue gas. 17, 30 and 40 wt% loadings of BILP-101 into PIM-1 were tested, resulting in mechanically stable films showing very good interfacial interaction due to the inherent H-bonding capability of the constituent materials. Gas transport studies showed that BILP-101/PIM-1 membranes exhibit high CO2 permeability (7200 Barrer) and selectivity over N2 (15). The selected hybrid membrane was further tested for CO2 separation using actual flue gas from a coal-fired power plant.

Targeted nanoparticles deliver siRNA to melanoma.

Melanoma is a severe skin cancer that often leads to death. To examine the potential of small interfering RNA (siRNA) therapy for melanoma, we have developed anisamide-targeted nanoparticles that can systemically deliver siRNA into the cytoplasm of B16F10 murine melanoma cells, which express the sigma receptor. A c-Myc siRNA delivered by the targeted nanoparticles effectively suppressed c-Myc expression in the tumor and partially inhibited tumor growth. More significant tumor growth inhibition was observed with nanoparticles composed of N,N-distearyl-N-methyl-N-2-(N'-arginyl) aminoethyl ammonium chloride (DSAA), a guanidinium-containing cationic lipid, than with a commonly used cationic lipid, 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP). Three daily injections of c-Myc siRNA formulated in the targeted nanoparticles containing DSAA could impair tumor growth, and the ED(50) of c-Myc siRNA was about 0.55 mg kg(-1). The targeted DSAA nanoparticles containing c-Myc siRNA sensitized B16F10 cells to paclitaxel (Taxol), resulting in a complete inhibition of tumor growth for 1 week. Treatments of c-Myc siRNA in the targeted nanoparticles containing DSAA also showed significant inhibition on the growth of MDA-MB-435 tumor. The enhanced anti-melanoma activity is probably related to the fact that DSAA, but not DOTAP, induced reactive oxygen species, triggered apoptosis, and downregulated antiapoptotic protein Bcl-2 in B16F10 melanoma cells. Thus, the targeted nanoparticles containing c-Myc siRNA may serve as an effective therapeutic agent for melanoma.