Wax from Pyrolysis of Waste Plastics as a Potential Source of Phase Change Material for Thermal Energy Storage

Over the past half-century, plastic consumption has grown rapidly due to its versatility, low cost, and unrivaled functional properties. Among the diff erent implemented strategies for recycling waste plastics, pyrolysis is deemed the most economical option. Currently, the wax obtained from the pyrolysis of waste plastics is mainly used as a feedstock to manufacture chemicals and fuels or added to asphalt for pavement construction, with no other applications of wax being reported. Herein, the thermal pyrolysis of three common waste polyolefin plastics: high-density polyethylene(HDPE), low-density polyethylene(LDPE), and polypropylene(PP), was conducted at 450 ℃. The waste plastics-derived waxes were characterized and studied for a potential new application: phase change materials(PCMs) for thermal energy storage(TES). Gas chromatography–mass spectrometry analysis showed that paraffin makes up most of the composition of HDPE and LDPE waxes, whereas PP wax contains a mixture of naphthene, isoparaffin, olefin, and paraffin. Diff erential scanning calorimetry(DSC) analysis indicated that HDPE and LDPE waxes have a peak melting temperature of 33.8 ℃ and 40.3 ℃, with a relatively high latent heat of 103.2 J/g and 88.3 J/g, respectively, whereas the PP wax was found to have almost negligible latent heat. Fourier transform infrared spectroscopy and DSC results revealed good chemical and thermal stability of HDPE and LDPE waxes after 100 cycles of thermal cycling. Performance evaluation of the waxes was also conducted using a thermal storage pad to understand their thermoregulation characteristics for TES applications.

Advances in the design and development of SARS-CoV-2 vaccines

Since the end of 2019,coronavirus disease 2019(COVID-19)caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)has spread worldwide.The RNA genome of SARS-CoV-2,which is highly infectious and prone to rapid mutation,encodes both structural and non-structural proteins.Vaccination is currently the only effective method to prevent COVID-19,and structural proteins are critical targets for vaccine development.Currently,many vaccines are in clinical trials or are already on the market.This review highlights ongoing advances in the design of prophylactic or therapeutic vaccines against COVID-19,including viral vector vaccines,DNA vaccines,RNA vaccines,live-attenuated vaccines,inactivated virus vaccines,recombinant protein vaccines and bionic nanoparticle vaccines.In addition to traditional inactivated virus vaccines,some novel vaccines based on viral vectors,nanoscience and synthetic biology also play important roles in combating COVID-19.However,many challenges persist in ongoing clinical trials.

Polyethylene glycol/polylactic acid block co‐polymers as solid–solid phase change materials

Phase change materials(PCMs)are promising thermal energy storage materials due to their high specific latent heat.Conventional PCMs typically exploit the solid–liquid(s–l)transition.However,leakage and leaching are common issues for solid–liquid PCMs,which have to be addressed before usage in practical applications.In contrast,solid–solid(s–s)PCMs would naturally overcome these issues due to their inherent form stability and homogeneity.In this study,we report a new type of s–s PCM based on chemically linked polyethylene glycol(PEG,the PCM portion)with polylactic acid(PLA,the support portion)in the form of a block co‐polymer.Solid‐solid latent heat of up to 56 J/g could be achieved,with melting points of between 44°C and 55°C.For comparison,PEG was physically mixed into a PLA matrix to form a PEG:PLA composite.However,the composite material saw leakage of up to 9%upon heating,with a corresponding loss in thermal storage capacity.In contrast,the mPEG/PLA block co‐polymers were found to be completely homogeneous and thermally stable even when heated above its phase transition temperature,with no observable leakage,demonstrating the superiority of chemical linking strategies in ensuring form stability.

Current Research Trends and Perspectives on Solid-State Nanomaterials in Hydrogen Storage

Hydrogen energy,with environment amicable,renewable,efficiency,and cost-effective advantages,is the future mainstream substitution of fossil-based fuel.However,the extremely low volumetric density gives rise to the main challenge in hydrogen storage,and therefore,exploring effective storage techniques is key hurdles that need to be crossed to accomplish the sustainable hydrogen economy.Hydrogen physically or chemically stored into nanomaterials in the solid-state is a desirable prospect for effective large-scale hydrogen storage,which has exhibited great potentials for applications in both reversible onboard storage and regenerable off-board storage applications.Its attractive points include safe,compact,light,reversibility,and efficiently produce sufficient pure hydrogen fuel under the mild condition.This review comprehensively gathers the state-of-art solid-state hydrogen storage technologies using nanostructured materials,involving nanoporous carbon materials,metal-organic frameworks,covalent organic frameworks,porous aromatic frameworks,nanoporous organic polymers,and nanoscale hydrides.It describes significant advances achieved so far,and main barriers need to be surmounted to approach practical applications,as well as offers a perspective for sustainable energy research.

Effectiveness of an ocular adhesive polyhedral oligomeric silsesquioxane hybrid thermo-responsive FK506 hydrogel in a murine model of dry eye

Dry eye is a common ocular disease that results in discomfort and impaired vision,impacting an individual’s quality of life.A great number of drugs administered in eye drops to treat dry eye are poorly soluble in water and are rapidly eliminated from the ocular surface,which limits their therapeutic effects.Therefore,it is imperative to design a novel drug delivery system that not only improves the water solubility of the drug but also prolongs its retention time on the ocular surface.Herein,we develop a copolymer from mono-functional POSS,PEG,and PPG(MPOSS-PEG-PPG,MPEP)that exhibits temperature-sensitive sol-gel transition behavior.This thermo-responsive hydrogel improves the water solubility of FK506 and simultaneously provides a mucoadhesive,long-acting ocular delivery system.In addition,the FK506-loaded POSS hydrogel possesses good biocompatibility and significantly improves adhesion to the ocular surface.In comparison with other FK506 formulations and the PEG-PPG-FK506(F127-FK506)hydrogel,this novel MPOSS-PEG-PPG-FK506(MPEP-FK506)hydrogel is a more effective treatment of dry eye in the murine dry eye model.Therefore,delivery of FK506 in this POSS hydrogel has the potential to prolong drug retention time on the ocular surface,which will improve its therapeutic efficacy in the management of dry eye.

Face Masks in the New COVID-19 Normal: Materials, Testing,and Perspectives

The increasing prevalence of infectious diseases in recent decades has posed a serious threat to public health.Routes of transmission differ,but the respiratory droplet or airborne route has the greatest potential to disrupt social intercourse,while being amenable to prevention by the humble facemask.Different types of masks give different levels of protection to the user.The ongoing COVID-19 pandemic has even resulted in a global shortage of face masks and the raw materials that go into them,driving individuals to self-produce masks from household items.At the same time,research has been accelerated towards improving the quality and performance of face masks,e.g.,by introducing properties such as antimicrobial activity and superhydrophobicity.This review will cover mask-wearing from the public health perspective,the technical details of commercial and home-made masks,and recent advances in mask engineering,disinfection,and materials and discuss the sustainability of mask-wearing and mask production into the future.

Flexible polymeric patch based nanotherapeutics against non-cancer therapy

Flexible polymeric patches find widespread applications in biomedicine because of their biological and tunable features including excellent patient compliance,superior biocompatibility and biodegradation,as well as high loading capability and permeability of drug.Such polymeric patches are classified into microneedles(MNs),hydrogel,microcapsule,microsphere and fiber depending on the formed morphology.The combination of nanomaterials with polymeric patches allows for improved advantages of increased curative efficacy and lowered systemic toxicity,promoting on-demand and regulated drug administration,thus providing the great potential to their clinic translation.In this review,the category of flexible polymeric patches that are utilized to integrate with nanomaterials is briefly presented and their advantages in bioapplications are further discussed.The applications of nanomaterials embedded polymeric patches in non-cancerous diseases were also systematically reviewed,including diabetes therapy,wound healing,dermatological disease therapy,bone regeneration,cardiac repair,hair repair,obesity therapy and some immune disease therapy.Alternatively,the limitations,latest challenges and future perspectives of such biomedical therapeutic devices are addressed.