Organic solvent free PbI₂ recycling from perovskite solar cells using hot water

Perovskite solar cells represent an emerging and highly promising renewable energy technology. However, the most efficient perovskite solar cells critically depend on the use of lead. This represents a possible environmental concern potentially limiting the technologiesâEurotm commercialization. Here, we demonstrate a facile recycling process for PbI2, the most common lead-based precursor in perovskite absorber material. The process uses only hot water to effectively extract lead from synthetic precursor mixes, plastic- and glass-based perovskites (92.6 âEuro" 10

Development of Biodegradable Food Packaging Materials from Agricultural Biomass

This study utilised maize husk fibres and pulp to prepare a biocomposite fabric for foodpackaging. The optimum conditions for extracting maize husk fibres were determinedexperimentally to be 5 g/l of sodium hydroxide concentration at 100 °C for 60 minutes and liquor ratio of 1:20. The fabric was manufactured by solution casting of maize husk pulp on a web prepared by aligning maize husk and sisal fibres using a deckle and frame. The sisal fibre content was varied from 5 to 50% at ratios ranging from 95:5 to 50:50 (maize: sisal fibres). The biodegradable fabric was characterised using three mechanical properties: tear strength, tensile strength, and abrasion resistance. The tear strength ranged from 0.79 MPa to 3.93 MPa whereas the tensile strength ranged from 13.35 MPa to 56.46 MPa, which conforms to the data available from literature. Abrasion tests verified that there was no mass loss at 5,000, 10,000 and 15,000 cycles. Overall, the study findings show that maize husk fibres can replace up to 80% of sisalfibres in materials for food packaging applications without compromising their quality. Keywords: Maize husk fibre, biocomposite, sisal fibres, food packaging

Optimizing a sustainable ultrasound assisted extraction method for the recovery of polyphenols from lemon by-products:comparison with hot water and organic solvent extractions

Response surface methodology (RSM) based on a three-factor and three-level Box–Behnken design was employed for optimizing the aqueous ultrasound-assisted extraction (AUAE) conditions, including extraction time (35–45 min), extraction temperature (45–55 °C) and ultrasonic power (150–250 W), for the recovery of total phenolic content (TPC) and rutin from lemon by-products. The independent variables and their values were selected on the basis of preliminary experiments, where the effects of five extraction parameters (particle size, extraction time and temperature, ultrasonic power and sample-to-solvent ratio) on TPC and rutin extraction yields were investigated. The yields of TPC and rutin were studied using a second-order polynomial equation. The optimum AUAE conditions for TPC were extraction time of 45 min, extraction temperature of 50 °C and ultrasonic power of 250 W with a predicted value of 18.10 ± 0.24 mg GAE/g dw, while the optimum AUAE conditions for rutin were extraction time of 35 min, extraction temperature of 48 °C and ultrasonic power of 150W with a predicted value of 3.20 ± 0.12 mg/g dw. The extracts obtained at the optimum AUAE conditions were compared with those obtained by a hot water and an organic solvent conventional extraction in terms of TPC, total flavonoid content (TF) and antioxidant capacity. The extracts obtained by AUAE had the same TPC, TF and ferric reducing antioxidant power as those achieved by organic solvent conventional extraction. However, hot water extraction led to extracts with the highest flavonoid content and antioxidant capacity. Scanning electron microscopy analysis showed that all the extraction methods led to cell damage to varying extents

EFFECTS OF DIFFERENT MICROENVIRONMENTAL CONDITIONS ON THE GROWTH AND DIFFERENTIATION OF DENTAL PULP STEM CELLS

Human teeth are very complex structures that are susceptible to many different pathologies due to poor dental health. Currently, there are many restorative methods to reestablish some of the function that teeth have, but the materials used in these methods all have drawbacks and cannot fully mimic the native teeth. Tissue engineering research groups have begun to explore regenerating bone or dental tissue using mesenchymal stem cells derived from the bone marrow. However, our group focuses on regenerating dental tissues using multipotent stem cells from dental pulp. Dental pulp stem cells (DPSCs) have shown similarities to bone marrow stem cells in in that they can differentiate into many cell types. Also, stem cells in general have shown that differentiation can be induced with microenvironmental factors such as growth factors and substrate properties. If enough is known about the cues that cells receive that induces differentiation, tissues could be engineered using the constructs and growth conditions necessary. To determine the effect of substrate stiffness on human DPSCs, cells were placed on polyacrylamide gels of varying stiffness and in varying growth factor conditions. The cells were then observed with light and confocal microscopy, and the amount of alkaline phosphatase (ALP) activity was measured. These tests gave an indication of growth and differentiation. It was seen that the growth patterns were different on the gels than they were on a glass control, but there was little difference between the two gels. Also, the growth factors did not appear to have a significant contribution to differentiation. Much work has been done to determine the effects of mechanical compression muscleoskeletal tissues, such as cartilage and bone. Dental tissues are also subject to loading throughout the day. Therefore, it was hypothesized that if dental pulp stem cells are compressed with pressure similar to that seen physiologically, it will induce differentiation to a bone or tooth-like lineage. To determine the effects of static compression on dental pulp stem cells, a custom compressive device was fabricated. The device was tested for usability and it was deemed acceptable for use. ALP assays were performed similar to the previous studies. Preliminary results showed that that after only 1 day of culture time, the compression did not have much of an effect on dental pulp stem cells, while it did have an effect on osteoblasts. More work is to be done to determine the effects of compressive forces on dental pulp stem cells

A Biodegradable Alternative to the Single-Use Cup

One hundred billion single-use cups are sent to landfills annually in the United States. Their production, usage, and disposal cause deforestation, pollution, and human health problems. Attempts have been made to produce more environmentally friendly tableware, however, these options are frequently not economically or logistically viable. This project strived to develop a single-use cup that meets the market need while remaining biodegradable and sustainably sourced. A financial and market analysis demonstrates the cup’s ability to enter the industry

Optimization of xylanase production by Streptomyces sp. P12-137 using response surface methodology and central composite design

Response surface methodology and central composite design were used to optimize a biosynthesis medium for the production of xylanases by Streptomyces sp. P12-137 in submerged fermentation culture at pH 5.0, with wheat bran as substrate. The three variables involved in this research were the wheat bran, potassium nitrate and xylose concentrations. Statistical analysis of the results showed that, in the range studied, xylose and potassium nitrate concentrations had a significant effect on xylanase production. The optimized biosynthesis medium contained (in %, w/v): wheat bran 1.0, KNO3 1.0, xylose 0.5. This medium resulted in a 3-fold increased level of the xylanase (27.77 UA/ml) production compared to the initial level (8.30 UA/ml) after 120 h of fermentation, whereas the value predicted by the quadratic model was 26.45 UA/ml

Human powered production tool for the renewable material, bamboo

Sustainable design in a simple manner usually involves the impact of the things we design - their manufacturing process, time of use, and final disposal - on the earth\u27s environment. In India, I was exposed to a different definition and concept of sustainable design, some similar to the West, and some rather different. When a particular object is related to its context, it becomes a part of the living system, making it human-centered and deeply rooted in the culture. It has to do more by defining a relationship between the object and the user environment. In order to attain sustainability in design, renewable materials and product systems play major roles in the entire process. In India, bamboo is available in abundance. As bamboo has many ecological and economic benefits, it is considered as one of the most versatile and sustainable materials. Many of the hand-made products from bamboo involve different weaving patterns that define structural strength and at the same time look aesthetically pleasant. People prefer hand tools to manufacture handmade products, as the tools require less maintenance, not need of power and are inexpensive to maintain. My objective in this research process was to improve the manufacturing systems by designing a hand tool, which can hold and split the bamboo efficiently. My design development process involved; to study impact of renewable materials on the environment, data collection of existing manufacturing systems for bamboo, to interview the locals regarding their needs of simple affordable manufacturing tool to split bamboo, to study and implement simple interface to use the tool. The tool, which I designed; is portable, has no power requirement, and is cost effective with less maintenance - very important features of the tool that could be used by the locals in rural areas. The tool has very few parts to assembly avoiding the difficulty for the users to go through the instructions, as most of the users are not literate and cannot read the instructions. This thesis paper encourages designers and more over the manufacturing industry to consider renewable resources, design for the environment, improved manufacturing systems and at the same time involves socio-cultural tradition, economic factors, which are equally significant for material and product development