Mechanical alloying is a solid-state powder processing technique that involves repeated cold welding, fracturing, and rewelding of powder particles in a high-energy ball mill. Originally developed about 50 years ago to produce oxide-dispersion-strengthened Ni- and Fe-based superalloys for aerospace and high temperature applications, it is now recognized as an important technique to synthesize metastable and advanced materials with a high potential for widespread applications. The metastable materials produced include supersaturated solid solutions, intermediate phases, quasicrystalline phases, amorphous alloys, and high-entropy alloys. Additionally, nanocrystalline phases have been produced in virtually every alloy system. Because of the fineness of the powders, their consolidation to full density without any porosity being present is a challenging problem. Several novel methods have been developed to overcome this issue. Powder contamination during milling and subsequent consolidation constitutes another issue; this can be resolved, though expensive. A number of applications have been developed for these novel materials. This review article presents an overview of the process of mechanical alloying, mechanism of grain refinement to nanometer levels, and preparation of materials such as nanocomposites and metallic glasses. The application of mechanical alloying to synthesize some advanced materials such as pure metals and alloys, hydrogen storage materials, and energy materials is described. The article concludes with an outlook on future prospects of this technique.

The apparently near-term effects of the monoclonal antibody BAN2401 in slowing the progression of prodromal Alzheimer’s disease (AD) has created cautious optimism about the therapeutic use of antibodies that neutralize cytotoxic soluble amyloid-β aggregates, rather than removing plaque. Plaque being protective, as it immobilizes cytotoxic amyloid-β, rather than AD’s causative agent. The presence of natural antibodies against cytotoxic amyloid-β implies the existence of a protective anti-AD immunity. Hence, for vaccines to induce a similar immunoresponse that prevents and/or delays the onset of AD, they must have adjuvants that stimulate a sole anti-inflammatory Th2 immunity, plus immunogens that induce a protective immunoresponse against diverse cytotoxic amyloid-β conformers. Indeed, amyloid-β pleomorphism may explain the lack of long-term protection by monoclonal antibodies that neutralize single conformers, like aducanumab. A situation that would allow new cytotoxic conformers to escape neutralization by previously effective monoclonal antibodies. Stimulation of a vaccine’s effective immunoresponse would require the concurrent delivery of immunogen to dendritic cells and their priming, to induce a polarized Th2 immunity. An immunoresponse that would produce besides neutralizing antibodies against neurotoxic amyloid-β oligomers, anti-inflammatory cytokines; preventing inflammation that aggravates AD. Because of age-linked immune decline, vaccines would be significantly more effective in preventing, rather than treating AD. Considering the amyloid-β’s role in tau’s pathological hyperphosphorylation and their synergism in AD, the development of preventive vaccines against both amyloid-β and tau should be considered. Due to convenience and cost, vaccines may be the only option available to many countries to forestall the impending AD epidemic.

We calculated the kinetics of chemical activation reactions of toluene with hydroxyl radical in the temperature range from 213 K to 2500 K and the pressure range from 10 Torr to the high-pressure limit by using multistructural variational transition state theory with the small-curvature tunneling approximation (MS-CVT/SCT) and using the system-specific quantum Rice-Ramsperger-Kassel method. The reactions of OH with toluene are important elementary steps in both combustion and atmospheric chemistry, and thus it is valuable to understand the rate constants both in the high-pressure, high-temperature regime and in the low-pressure, low-temperature regime. Under the experimental pressure conditions, the theoretically calculated total reaction rate constants agree well with the limited experimental data, including the negative temperature dependence at low temperature. We find that the effect of multistructural anharmonicity on the partition functions usually increases with temperature, and it can change the calculated reaction rates by factors as small as 0.2 and as large as 4.2. We also find a large effect of anharmonicity on the zero-point energies of the transition states for the abstraction reactions. We report that abstraction of H from methyl should not be neglected in atmospheric chemistry, even though the low-temperature results are dominated by addition. We calculated the product distribution, which is usually not accessible to experiments, as a function of temperature and pressure.

The removal of soluble cyclic ether contaminants, such as dioxane and THF, produced in industrial chemical processes from water is of great importance for environmental protection and human health. Here we report that nonporous adaptive crystals of perethylated pillar[5]arene (EtP5) and pillar[6]arene (EtP6) work as adsorbents for cyclic ether contaminant removal via host-guest complexation at the solid-solution interface. Nonporous EtP6 crystals have the ability to adsorb dioxane from water with the formation of 1:2 host-guest complex crystals, while EtP5 crystals cannot. However, both guest-free EtP5 and EtP6 crystals remove THF from water with EtP5 having a better capacity. This is because EtP5 forms a 1:2 host-guest complex with THF via host-guest complexation at the solid-solution interface while EtP6 forms a 1:1 host-guest complex with THF. EtP6 also shows the ability to selectively remove dioxane from water even in the presence of THF. Moreover, the reversible transitions between nonporous guest-free EtP5 and EtP6 structures and guest-loaded structures make them highly recyclable.

With the increase of communication frequency, terahertz (THz) communication technology has been an important research field; particularly the terahertz modulator is becoming one of the core devices in THz communication system. The modulation performance of a THz communication system depends on the characterization of THz modulator. THz modulators based on different principles and materials have been studied and developed. However, they are still on the way to practical application due to low modulation speed, narrow bandwidth, and insufficient modulation depth. Therefore, we review the research progress of THz modulator in recent years and evaluate devices critically and comprehensively. We focus on the working principles such as electric, optical, optoelectrical, thermal, magnetic, programmable metamaterials and nonlinear modulation methods for THz wave with semiconductors, metamaterials, and 2D materials (such as graphene, molybdenum disulfide, and tungsten disulfide). Furthermore, we propose a guiding rule to select appropriate materials and modulation methods for specific applications in THz communication.

Intratumoral hypoxia extremely limits the clinic applications of photodynamic therapy (PDT). Endoperoxides allow thermally releasing singlet oxygen (¹O₂) in a defined quantity and offer promising opportunities for oxygen-independent PDT treatment of hypoxic tumors. However, previous composite systems by combining endoperoxides with photothermal reagents may result in unpredicted side effects and potential harmful impacts during therapy in vivo. Herein, we de novo design an all-in-one polymer carrier, which can photothermally release ¹O₂. The strategy has been demonstrated to effectively enhance the production of ¹O₂ and realize the photodamage in vitro, especially in hypoxic environment. Additionally, the polymer carrier accumulates into tumor after intravenous injection via the enhanced permeation and retention effects and accelerates the oxygen-independent generation of ¹O₂ in tumors. The oxidative damage results in good inhibitory effect on tumor growth. Realization of the strategy in vivo paves a new way to construct photothermal-triggered oxygen-independent therapeutic platform for clinical applications.

To date, how the shape of nanomaterials influences their biological properties is poorly understood, due to the insufficient controllability of current preparative methods, especially in the shape and size of nanomaterials. In this paper, we achieved the precise syntheses of nanoscale unimolecular cylindrical polymer brushes (CPBs) and spherical polymer nanoparticles (SPNPs) with the same volume and surface chemistry, which ensured that shape was essentially the only variable when their biological performance was compared. Accurate shape effects were obtained. Impressively, the CPBs had remarkable advantage in tissue penetration over the SPNPs. The CPBs also exhibited higher cellular uptake and rapider body clearance than the SPNPs, whereas the SPNPs had longer blood circulation time, rapider tumor vascular extravasation, and higher tumor accumulation than the CPBs. Additionally, this work also provided a controllable synthesis strategy for nanoscale unimolecular SPNPs by integrating 21 CPBs to a β-cyclodextrin core, whose diameter in dry state could be up to 45 nm.

We review some recent progress in the exploration of pseudospin-1 physics using dielectric photonic crystals (PCs). We show some physical implications of the PCs exhibiting an accidental degeneracy induced conical dispersion at the \mathrm{\Gamma } point, such as the realization of zero refractive index medium and the zero Berry phase of a loop around the nodal point. The photonic states of such PCs near the Dirac-like point can be described by an effective spin-orbit Hamiltonian of pseudospin-1. The wave propagation in the positive, negative, and zero index media can be unified within a framework of pseudospin-1 description. A scale change in PCs results in a rigid band shift of the Dirac-like cone, allowing for the manipulation of waves in pseudospin-1 systems in much the same way as applying a gate voltage in pseudospin-1/2 graphene. The transport of waves in pseudospin-1 systems exhibits many interesting phenomena, including super Klein tunneling, robust supercollimation, and unconventional Anderson localization. The transport properties of pseudospin-1 systems are distinct from their counterparts in pseudospin-1/2 systems, which will also be presented for comparison.

The microwave properties of composites containing Fe-based ferromagnetic microwires and carbon fibres have been investigated as part of a campaign to bring added functionalities into structural composites. A transmission window observed in 1-6 GHz demonstrates double-negative (DNG), i.e., metamaterial characteristics in the composites containing short-cut carbon fibres and a parallel array of microwires; the metamaterial characteristic is due to the ferromagnetic resonance and a plasmonic behaviour, as short carbon fibres are proved to ameliorate DNG properties through enhancing the impedance of the composites. In parallel, magnetically tunable metamaterial features are realised in composites containing continuous carbon fibres and microwires, which can be switched on/off via rotating the electrical excitation direction. Such structural composites integrated with metamaterial features (termed as metacomposites) are potentially useful for active cloaking applications among others.

Niacin metal-organic frameworks (MOFs) encapsulated microcapsules with alginate shells and copper-/zinc-niacin framework cores were in situ synthesized by using a microfluidic electrospray approach for wound healing. As the alginate shells were bacteria-responsively degradable, the niacin MOFs encapsulated microcapsules could intelligently, controllably, and programmably release calcium, copper, and zinc ions, depending on the degree of infections. The released ions could not only kill microbes by destroying their membrane and inducing the outflow of nutrient substance, but also activate copper/zinc superoxide dismutase (Cu/Zn-SOD) to eliminate oxygen free radicals and rescue the cells from oxidative stress injury. Furthermore, the simultaneously released niacin could promote hemangiectasis and absorption of functional metal ions. Thus, the niacin MOFs encapsulated microcapsules were imparted with outstanding antibacterial, antioxidant, and angiogenesis properties. Based on an in vivo study, we have also demonstrated that the chronic wound healing process of an infected full-thickness skin defect model could be significantly enhanced by using the niacin MOFs encapsulated microcapsules as therapeutic agent. Therefore, the microfluidic electrospray niacin MOFs encapsulated microcapsules are potential for clinical applications.