Scientific, sustainability and regulatory challenges of cultured meat

Producing meat without the drawbacks of conventional animal agriculture would greatly contribute to future food and nutrition security. This Review Article covers biological, technological, regulatory and consumer acceptance challenges in this developing field of biotechnology. Cellular agriculture is an emerging branch of biotechnology that aims to address issues associated with the environmental impact, animal welfare and sustainability challenges of conventional animal farming for meat production. Cultured meat can be produced by applying current cell culture practices and biomanufacturing methods and utilizing mammalian cell lines and cell and gene therapy products to generate tissue or nutritional proteins for human consumption. However, significant improvements and modifications are needed for the process to be cost efficient and robust enough to be brought to production at scale for food supply. Here, we review the scientific and social challenges in transforming cultured meat into a viable commercial option, covering aspects from cell selection and medium optimization to biomaterials, tissue engineering, regulation and consumer acceptance

Microstructure and morphology evolution in chemical solution deposited semiconductor films: 3. PbSe on GaAs vs. Si substrate

The microstructure and morphology evolution in nanocrystalline PbSe films chemically deposited on GaAs(100) and GaAs(111) substrates were compared to PbSe films on Si(100) under the same conditions. On GaAs substrates, dense and continuous PbSe films were obtained. We show that the temperature dependent morphological changes on GaAs substrates occurred as a result of increased sample thickness due to higher reaction rates. Notably, the deposition of PbSe on Si(100) did not lead to continuous films and no preferred orientation was observed. The improved wetting between PbSe and GaAs appears to be a key factor responsible for the differences observed on the two substrates

Microstructure and morphology evolution in chemical solution deposited PbSe films on GaAs(100)

We have studied the microstructure and morphology evolution in PbSe films chemically deposited on GaAs(100) substrates. The films consisted of a single phase of nanocrystalline rocksalt PbSe. The deposition temperature was found to be an important parameter which strongly influences the film morphology. A gradual transition to strong (111) texture was obtained with increasing deposition temperature, accompanied by a significant increase in crystallite size. Transmission electron microscopy (TEM) cross-sections showed two distinct regions. A layer of small, rounded crystals near the GaAs/PbSe interface above which a second region composed of columnar, $\langle$111$\rangle$ oriented crystallites was observed. High resolution TEM and Fourier analysis showed that the first layer of crystallites are in epitaxial registry with the GaAs substrate, in spite of the large (8%) lattice mismatch and the presence of a thin, amorphous interfacial layer

Microstructure and morphology evolution in chemical solution deposited semiconductor films: 2. PbSe on As face of GaAs(111)

Nanocrystalline PbSe films were grown on GaAs(100) and on the As face of GaAs(111) substrates using chemical solution deposition. The microstructure of the films was found to be strongly affected by the deposition temperature over a surprisingly narrow temperature range. In PbSe deposited on GaAs(100), gradual increase in crystallite size and transition to $\langle$111$\rangle$ texture were obtained with increasing temperature. In contrast with PbSe deposited on GaAs(100), the $\langle$111$\rangle$ texture in PbSe on GaAs(111) dominated throughout the deposition temperature range. Since temperature directly affects reaction rate, the temperature-dependent morphological changes observed in this work occur primarily due to increasing sample thickness

Optical properties of size quantized PbSe films chemically deposited on GaAs

PbSe films were chemically deposited with a range of controlled microstructures, from nanocrystalline to monocrystalline films. The crystal size in the nanocrystalline films was controlled in a range 7 to 25 nm with a fairly narrow size distribution, which allowed fine-tuning of the PbSe energy gap. The optical properties of the films were investigated using infrared (IR) transmission and IR photoluminescence measurements. The nanocrystalline PbSe films showed single bandgap values in the technologically important near-IR region. Two bandgap values, corresponding to both bulk and confined nanocrystals, were obtained for films with mixed microstructure. Strong blue shifts in both the absorption and emission peaks of the nanocrystalline layers were obtained. The bandgaps of the PbSe films were found to be in good agreement with theoretical calculations. The results point out the potential of these films for nanoscale optical device applications operating in the near-IR range