Microalgae dewatering is a major obstruction to industrial-scale processing of microalgae for biofuel prodn. The dil. nature of harvested microalgal cultures creates a huge operational cost during dewatering, thereby, rendering algae-based fuels less economically attractive. Currently there is no superior method of dewatering microalgae. A technique that may result in a greater algal biomass may have drawbacks such as a high capital cost or high energy consumption. The choice of which harvesting technique to apply will depend on the species of microalgae and the final product desired. Algal properties such as a large cell size and the capability of the microalgae to autoflocculate can simplify the dewatering process. This article reviews and addresses the various technologies currently used for dewatering microalgal cultures along with a comparative study of the performances of the different technologies.

Dewatering of microalgal cultures : a major bottleneck to algae-based fuels

Chemical vapour deposition (CVD) is a powerful technology for producing high-quality solid thin films and coatings Although widely used in modern industries, it is continuously being developed as it is adapted to new materials Today, CVD synthesis is being pushed to new heights with the precise manufacturing of both inorganic thin films of 2D materials and high-purity polymeric thin films that can be conformally deposited on various substrates In this Primer, an overview of the CVD technique, including instrument construction, process control, material characterization and reproducibility issues, is provided By taking graphene, 2D transition metal dichalcogenides (TMDs) and polymeric thin films as typical examples, the best practices for experimentation involving substrate pretreatment, high-temperature growth and post-growth processes are presented Recent advances and scaling-up challenges are also highlighted By analysing current limitations and optimizations, we also provide insight into possible future directions for the method, including reactor design for high-throughput and low-temperature growth of thin films This Primer on chemical vapour deposition summarizes current and emerging experimental set-ups as well as common characterization approaches used to determine thin film formation and quality as applied to graphene and other novel 2D materials

Chemical vapour deposition

Recent advances in hybrid organic-inorganic materials with spatial architecture for state-of-the-art applications

In the present work, magnesium (Mg) AZ31 alloy was coated with a multifunctional membrane layer composed of ZnO nanoparticles (NPs) embedded in a poly(lactic acid) (PLA) matrix. We aimed to produce a stable coating that would be used to control the degradation rate of the Mg alloy and promote a local antibacterial activity. ZnO NPs were dispersed at 5 and 10 wt % in a PLA solution and dip-coated onto the AZ31 substrate. Surface topography, chemical composition, thickness, electrochemical corrosion performance, mass variation, antibacterial activity, adhesion performance, and cytotoxicity of an uncoated control and coated alloys were investigated. The results indicated that the incorporation of ZnO NPs at various concentrations affords a dramatic control over surface topography and degradation rates under in vitro and in vivo environmental conditions when compared to the uncoated Mg alloy control. In addition, the results confirmed that the coated layer exerts antibacterial properties and supports cell gro...

A Multifunctional Zinc Oxide/Poly(Lactic Acid) Nanocomposite Layer Coated on Magnesium Alloys for Controlled Degradation and Antibacterial Function.

Chemical vapour deposition (CVD) enables nanoscale control for the synthesis of high-purity polymer thin films. Ultrathin (<20 nm) and ultrasmooth (<1 nm r.m.s. roughness) layers of CVD polymers can conform to the geometry of the growth surface. This Review focuses on CVD polymerization methods adapted from solution chemistry for selectively forming different classes of macromolecules. The mechanistically based CVD approaches provide full retention of the monomer’s organic functional groups and thus provide a rational basis for designing and optimizing film characteristics for a diverse array of applications. These include conjugated polymers for energy storage, thin dielectrics for low-power, flexible devices and responsive hydrogels for controlled drug release. Systematic variation in the CVD process parameters provides remarkable control of π–π stacking in conducting polymers, mesh sizes in hydrogels, crystallographic texture, surface energy, permeation rates of molecules and ions, optoelectronic properties and switchable smart behaviour. The initial research focus on process fundamentals, including adsorption, reaction kinetics, mass transport and conformality, formed a strong basis for the recent rapid expansion of materials, applications and scale-up activities in multiple laboratories. The materials and approaches used in CVD polymerization are also extending into hybrid inorganic/organic materials and devices. Chemical vapour deposition (CVD) enables the synthesis of high-purity, pinhole-free and conformal polymer thin films. This Review discusses the recent breakthroughs in mechanistically based CVD polymerization processes and designing CVD polymers for a diverse array of applications.

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Nanoscale control by chemically vapour-deposited polymers

Initiated Chemical Vapor Deposition: A Versatile Tool for Various Device Applications

To achieve adhesion between two arbitrary substrates, a sub-minute curable dry nanoadhesive was devised in a one-step manner. The dry adhesive is composed of a copolymer film containing poly(glycidyl methacrylate) (pGMA) and poly(2-(dimethylamino)ethyl methacrylate) (pDMAEMA) segments, where the tertiary amine moiety in pDMAEMA acts as an initiator that triggers the ring-opening reaction of the epoxy ring in pGMA, leading to a self-cross-linking of the epoxide groups in pGMA. Optimization of curing condition resulted in dramatic enhancement of the adhesion strength to values exceeding 250 N/cm2 of shear strength and 32.5 N/25 mm of peel strength. Also, strong bonds are observed in various types of substrate materials including glass, latex rubber, Si wafer, and many polymeric films to each other. Moreover, it maintained excellent adhesion against harsh mechanical, thermal, and chemical stresses. The copolymer-based nanoadhesive developed in this study will be highly advantageous for emerging flexible and ...

A Sub-minute Curable Nanoadhesive with High Transparency, Strong Adhesion, and Excellent Flexibility

A new fabrication method for an ultrathin (500 nm thick) pressure-sensitive adhesive (PSA) was demonstrated by utilizing a series of in situ cross-linked viscoelastic copolymer films. Viscoelastic films composed of poly(2-hydroxyethyl acrylate-co-2-ethylhexyl acrylate) were synthesized successfully in a one-step manner by an initiated chemical vapor deposition (iCVD) process, where free-radical polymerization is triggered in the vapor phase either by heat or UV, or a combination of both. In particular, the photoinitiated chemical vapor deposition method generated a highly cross-linked polymer film, whereas cross-linking of the copolymer film was suppressed greatly in the conventional thermal iCVD method. A combination of thermal and photoinitiated chemical vapor deposition could regulate the cross-linking density of the copolymer films. We controlled the cross-linking density of the copolymer films to exhibit a viscoelastic property so that they would readily adhere to various kinds of substrates with onl...

Solvent-Free Deposition of Ultrathin Copolymer Films with Tunable Viscoelasticity for Application to Pressure-Sensitive Adhesives

A cross-linked hydrogel-coated membrane was fabricated to achieve simple but highly efficient separation of bio-lipids directly from an aqueous microalgal culture medium. The membrane is composed of a stainless steel membrane coated conformally with a cross-linked hydrogel, poly(2-hydroxyethyl methacrylate) (pHEMA), synthesized by a photo-initiated chemical vapor deposition (piCVD) process. The pHEMA-coated membrane has hydrophilicity and underwater-oleophobicity for efficient separation of a bio-lipid-in-hexane/water mixture by gravity. The conformal pHEMA film-coated membrane enables extremely high oil rejection performance with intrusion pressure of 6.1 kPa and water permeation flux of 6.5×103 L m-2 h-1, with excellent separation efficiency greater than 98.0%.

A hydrogel-coated membrane for highly efficient separation of microalgal bio-lipid

Demand of adhesives that are strong but ultrathin with high flexibility, optical transparency, and long-term stability has been rapidly growing recently. Here, we suggest a thermally curable, “sticky” nanoadhesive with outstanding adhesion strength accomplished by single-side deposition of the nanoadhesive on arbitrary substrates. The sticky nanoadhesive is composed of an ionic copolymer film generated from two acrylate monomers with tertiary amine and alkyl halide functionalities, formed by a solvent-free method, initiated chemical vapor deposition (iCVD). Because of the low glass transition temperature (Tg) of the copolymer (−9 °C), the ionic copolymer shows a viscoelastic behavior that makes the adhesive attachable to various substrates, regardless of the substrate materials. Moreover, the copolymer film is thermally curable via a cross-linking reaction between the alkyl halide and tertiary amine functionalities, which substantially increased the adhesion strength of the 500 nm thick nanoadhesive great...

Heeyeon Moon

Papers

Initiated Chemical Vapor Deposition: A Versatile Tool for Various Device Applications

A Sub-minute Curable Nanoadhesive with High Transparency, Strong Adhesion, and Excellent Flexibility

Solvent-Free Deposition of Ultrathin Copolymer Films with Tunable Viscoelasticity for Application to Pressure-Sensitive Adhesives

A hydrogel-coated membrane for highly efficient separation of microalgal bio-lipid

Thermally Fast-Curable, "Sticky" Nanoadhesive for Strong Adhesion on Arbitrary Substrates.