Raman P Subrahmanyam

• Doctor of Engineering
• scientific co-worker at Hamburg University of Technology

In this work, nanostructured and transparent cellulose aerogels are synthesized via a purely salt induced approach from non‐modified microcrystalline cellulose type II. The production process requires in contrast to state of the art methods no pretreatment of cellulose or use of expensive cellulose‐solvents: it consists of hydrogel formation via cr...

In this chapter, we discuss the process of supercritical drying as it relates to the production of aerogels. What was once a heuristic technique typically performed using overly conservative process rules can now be quantitatively designed and efficiently implemented. Herein, thermodynamic and kinetic considerations of supercritical drying are revi...

In this work, organic aerogels from spent ground coffee and apple pomace were prepared and characterized for the first time. Apple aerogel was found to be much lighter than that from coffee (0.19 vs. 0.016 g/cm³, whereas the specific surface areas are comparable (229 vs. 208 m²/g). Being intrinsically hydrophilic, these aerogels were silanized, bot...

Protein aerogel particles prepared by supercritical-CO2-drying (SCD) of ground whey protein (WP) hydrogels (20% w/w, pH 5.7) were converted into oleogels by dispersion in selected edible oils (castor, cod liver, corn, flaxseed, MCT, peanut and sunflower oil). The obtained oleogels were analysed for oil content, microstructure, rheological propertie...

Aerogels are a class of open nonfluid porous solid materials known for their low density, high specific surface area, and accessible pores. This combination of characteristics makes them highly promising for a wide gamut of applications ranging from thermal and acoustic insulation, catalysts and sensors, adsorbents and absorbents, energy storage, c...

Textile engineering can offer a multi-scale toolbox via various fiber or textile fabrication methods to obtain woven or nonwoven aerogels with different structural and mechanical properties to overcome the current limitations of polysaccharide-based aerogels, such as poor mechanical properties and undeveloped shaping techniques. Hereby, a high visc...

Chronic non-healing wounds represent a substantial economic burden to healthcare systems and cause a considerable reduction in quality of life for those affected. Approximately 0.5–2% of the population in developed countries are projected to experience a chronic wound in their lifetime, necessitating further developments in the area of wound care m...

In the last decade, the uses and applications of aerogels have garnered significant scientific curiosity in the aerogel community. Furthermore, renewed focus on the supercritical CO2 drying methodology of aerogels has expanded the material scope to several biopolymer systems that now offer new avenues for material, property and application explorat...

Calcium-alginate aerogels augmented with zinc and silver can provide the next generation superabsorbent medical devices for advanced wound care with high cell and tissue tolerability and controlled compound release rates during wound healing. In this study, we addressed the fabrication and metal detection of alginate-based aerogels with these immun...

The first evidence of solvent spillage under subcritical conditions during aerogel production is presented. The main objective was to understand the underlying phenomena controlling the solvent extraction kinetics during autoclave pressurisation. Alginate, silica and polyurethane as gels and ethanol, methyl ethyl ketone and ethanol/water as solvent...

This work presents a novel route toward porous scaffolds for tissue engineering and regenerative medicine (TERM) applications. Hybrid cryogels with gelatin, gellan gum, carboxymethylcellulose, and lignin were prepared by a two-step process. Textural properties of the cryogels were analyzed by SEM and micro-computed tomography. The results indicated...

The authors wish to make the following correction to their paper [1]. Equations (10) and (11)are empirically derived curve fitting equations from a calibration plot (Figure S1 in [1]) that werecomputed to calculate the concentration (wt %) of a DMSO–water mixture in dependence of its density.However, the given equations contain rounded values for th...

Full video: https://www.youtube.com/watch?v=xVXYXQqUVos Although the first reports on aerogels made by Kistler in the 1930s dealt with aerogels from both inorganic oxides (silica and others) and biopolymers (gelatin, agar, cellulose), only recently have biomasses been recognized as an abundant source of chemically diverse macromolecules for functi...

Aerogels are three-dimensional ultra-light porous structures whose characteristics make them exciting candidates for research, development and commercialization leading to a broad scope of applications ranging from insulation and catalysis to regenerative medicine and pharmaceuticals. Biopolymers have recently entered the aerogel foray. In order to...

The present invention relates to a process for preparing a porous material, at least comprising the steps of providing a mixture (I) comprising a water soluble polysaccharide, at least one compound suitable to react as cross-linker for the polysaccharide or to release a cross-linker for the polysaccharide, and water, and preparing a gel (A) compris...

A novel technique for preparation of alginate aerogels, that utilizes high pressure CO2, is presented. In pressurized carbon dioxide at 5 MPa and 298 K, a suspension of calcium carbonate dispersed in sodium alginate solution undergoes irreversible gelation without additional pH modifiers or crosslinkers. Solvent exchange to ethanol at ambient condi...

A facile deposition method of 3D photonic crystals made of yttrium-stabilized zirconia (YSZ) was developed. YSZ nanoparticles with primary particle size below 10 nm and cubic crystalline phase were synthesized by hydrothermal treatment of solutions of zirconyl nitrate, yttrium nitrate and acetylacetone. Before coassembly with polystyrene (PS) micro...

High-performance carriers of active compounds processed in a sustainable manner are being prospected in the health care industry and the life science sector in general. The preparation of natural product-based nanoporous materials is regarded as an upgraded process that fulfills the above requirements. The drying of covalently crosslinked protein-b...