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•AM processes are classified based on ISO/ASTM standard and typical commercial materials are listed.•Fundamentals of AM process categories in terms of speed, resolution and specific ...energy are discussed.•Recent applications of new additive manufacturing (AM) materials such as smart materials, ceramics, electronics, biomaterials and composites are reviewed.•3D printing is no longer a standalone process but an integral part of a multi-process system or an integrated process of multiple systems.
3D printing is emerging as an enabling technology for a wide range of new applications. From fundamentals point of view, the available materials, fabrication speed, and resolution of 3D printing processes must be considered for each specific application. This review provides a basic understanding of fundamentals of 3D printing processes and the recent development of novel 3D printing materials such as smart materials, ceramic materials, electronic materials, biomaterials and composites. It should be noted that the versatility of 3D printing materials comes from the variety of 3D printing systems, and all the new printers or processes for novel materials have not gone beyond the seven categories defined in ISO/ASTM standard. However, 3D printing should never be seen as a standalone process, it is becoming an integral part of a multi-process system or an integrated process of multiple systems to match the development of novel materials and new requirements of products.
The current state-of-the-art metal additive manufacturing (AM) process still cannot meet the high industry requirements in terms of surface roughness. In addition, there are limited ISO/ASTM ...standards on the post-processing of metal AM components. Considerable efforts have been made to close these current gaps and challenges for standardization. In this review, First, all the existing ISO/ASTM standards under the jurisdiction of ASTM Committee F42 on additive manufacturing technologies are briefly discussed. Second, two of the most promising additive manufacturing processes: powder bed fusion (PBF) and directed energy deposition (DED), as well as their common defects of AM components, are thoroughly reviewed. The build quality, surface finish characteristics, and dimensional integrity of the as-built AM components are still not satisfactory (i.e., Ra > 5 µm and Rz > 100 µm). Third, the review is focused on identifying potential solutions to surface-finish complex additive manufactured geometries and reduce the surface roughness to meet the industry requirements (i.e., Ra < 1 µm and Rz < 20 µm). Current state-of-the-art surface finishing techniques, their material removal mechanisms, process parameters, advantages, and limitations to post-process PBF components are discussed. The technical gaps and future perspectives in enhancing the surface quality of AM components are outlined.
Catalysts in a relay: A synthetic method for delivering highly substituted isoquinolines has been developed (see scheme; Cp*=C5Me5, DMF=N,N‐dimethylformamide, ...TEMPO=2,2,6,6‐tetramethylpiperidine‐1‐oxyl). A preliminary mechanistic study showed that the rhodium and copper cooperate synergistically in the multistep sequence.
Internal concentration polarization (ICP) in substrate layer is one of the most critical bottlenecks of the forward osmosis (FO) process. In this study, we explored the use of metal–organic ...frameworks (MOFs) as a removable filler to prepare MOF-based porous matrix membranes (PMMs) for improving the mass transfer in the FO substrates and hence controlling the ICP. MOF-based porous matrix substrates (PMSs) with three different types of MOFs were prepared via phase inversion by adding MOF particles into the polyacrylonitrile (PAN) dope solution. A thin selective layer was prepared using a layer-by-layer (LbL) deposition method on top of the porous matrix FO substrate. The bond dissociation energy (BDE) between metal ions and organic linker of MOF particles played an important role for the selection of fillers of PMMs. For MOF particles with lower BDE (<~200kJ/mol), the corresponding MOF-based porous matrix FO membranes had higher membrane bulk porosity. This study shows the effect of different types of MOF particles in MOF-based porous matrix FO substrate for controlling the ICP in FO application for the first time, which provides an additional dimension for ICP control in osmotically-driven membrane processes.
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•MOF-based porous matrix membranes (PMMs) were used as FO substrates.•The PMM had improved membrane bulk porosity and substrate water permeability.•The bond dissociation energy of MOF particles played an important role.•All PMMs showed reduced S value compared to the control membrane.
Polaritons-hybrid light-matter excitations-enable nanoscale control of light. Particularly large polariton field confinement and long lifetimes can be found in graphene and materials consisting of ...two-dimensional layers bound by weak van der Waals forces
(vdW materials). These polaritons can be tuned by electric fields
or by material thickness
, leading to applications including nanolasers
, tunable infrared and terahertz detectors
, and molecular sensors
. Polaritons with anisotropic propagation along the surface of vdW materials have been predicted, caused by in-plane anisotropic structural and electronic properties
. In such materials, elliptic and hyperbolic in-plane polariton dispersion can be expected (for example, plasmon polaritons in black phosphorus
), the latter leading to an enhanced density of optical states and ray-like directional propagation along the surface. However, observation of anisotropic polariton propagation in natural materials has so far remained elusive. Here we report anisotropic polariton propagation along the surface of α-MoO
, a natural vdW material. By infrared nano-imaging and nano-spectroscopy of semiconducting α-MoO
flakes and disks, we visualize and verify phonon polaritons with elliptic and hyperbolic in-plane dispersion, and with wavelengths (up to 60 times smaller than the corresponding photon wavelengths) comparable to those of graphene plasmon polaritons and boron nitride phonon polaritons
. From signal oscillations in real-space images we measure polariton amplitude lifetimes of 8 picoseconds, which is more than ten times larger than that of graphene plasmon polaritons at room temperature
. They are also a factor of about four larger than the best values so far reported for phonon polaritons in isotopically engineered boron nitride
and for graphene plasmon polaritons at low temperatures
. In-plane anisotropic and ultra-low-loss polaritons in vdW materials could enable directional and strong light-matter interactions, nanoscale directional energy transfer and integrated flat optics in applications ranging from bio-sensing to quantum nanophotonics.
3D printing is an emerging technology and has attracted massive attention in recent years. This article focuses on the recent developments on enhancing the membrane module design with 3D printing ...technology. With the recent advancement of 3D printing technology, breakthroughs in fabricating novel membrane module components are expected in the near future. Improvement of 3D printing technologies in terms of resolution, materials and speed should assure the production of various membrane module components with high efficiency.
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•This article discusses the designs of membrane modules via 3D printing technology•Resolution and materials play important roles during the selection of a 3D printer.•Considerations in designing 3D-printed membrane modules are presented.•The opportunities and future directions are outlined with examples.
The development of opioid-induced analgesic tolerance and hyperalgesia is a clinical challenge for managing chronic pain. Adaptive changes in protein translation in the nervous system are thought to ...promote opioid tolerance and hyperalgesia; however, how opioids drive such changes remains elusive. Here, we report that mammalian target of rapamycin (mTOR), which governs most protein translation, was activated in rat spinal dorsal horn neurons after repeated intrathecal morphine injections. Activation was triggered through μ opioid receptor and mediated by intracellular PI3K/Akt. Spinal mTOR inhibition blocked both induction and maintenance of morphine tolerance and hyperalgesia, without affecting basal pain perception or locomotor functions. These effects were attributed to the attenuation of morphine-induced increases in translation initiation activity, nascent protein synthesis, and expression of some known key tolerance-associated proteins, including neuronal NOS (nNOS), in dorsal horn. Moreover, elevating spinal mTOR activity by knocking down the mTOR-negative regulator TSC2 reduced morphine analgesia, produced pain hypersensitivity, and increased spinal nNOS expression. Our findings implicate the μ opioid receptor-triggered PI3K/Akt/mTOR pathway in promoting morphine-induced spinal protein translation changes and associated morphine tolerance and hyperalgesia. These data suggest that mTOR inhibitors could be explored for prevention and/or reduction of opioid tolerance in chronic pain management.
Pressure-driven membranes with high porosity can potentially be fabricated by removing template, such as low water stability metal-organic frameworks (MOFs) or other nanoparticles, in polymeric ...matrix. We report on the use of benign MOFs as green template to enhance porosity and interconnectivity of the water treatment membranes. Significantly enhanced separation performance was observed which might be attributed to the mass transfer coefficient of the substrate layer increased in ultrafiltration (UF) application.
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•Multiphase hydrodynamic finishing reduces the surface roughness of L-PBF fuel nozzles.•Direct metal laser sintered IN625 fuel injection/spray nozzles are surface finished.•Profile ...and areal surface roughness reduced uniformly across all nozzle branches.•The peak height above the core surface Spk in the inlet section reduced by 75 %.•X-CT inspection showed dimensional deviations ≤ 100 μm in the nozzles.
Laser powder bed fused (L-PBF) components have poor surface finish quality that hinders their use in practical applications. Surface finishing the complex passages in the L-PBF components is particularly challenging. We aimed to produce a consistent surface finish on the internal passages of direct metal laser sintered (DMLS) Inconel 625 fuel nozzles—regardless of the as-built non-uniform surface—using a multi-jet hydrodynamic finishing technique. We effectively harnessed the hydrodynamic intensity and surface finished the fuel injection/spray tips comprising multiple branches. We found profile and areal surface roughness reduced up to 90 % across all branches. Also, the peak height above the core surface Spk at the nozzle inlet reduced by 40–75 %. X-ray computed tomography (X-CT) inspection post-finishing showed that roundness and circularity of the injection/spray tips improved, while most critical nozzle dimensions were within the tolerance. The results lend further credence that the proposed technique: Multi-jet hydrodynamic cavitation abrasive finishing (MJ-HCAF) can be used to surface-finish and deploy the L-PBF fuel nozzles in practical applications—ensuring safe implementation.
Abstract
The hypoxic tumor microenvironment has been implicated in immune escape, but the underlying mechanism remains elusive. Using an in vitro culture system modeling human T cell dysfunction and ...exhaustion in triple-negative breast cancer (TNBC), we find that hypoxia suppresses immune effector gene expression, including in T and NK cells, resulting in immune effector cell dysfunction and resistance to immunotherapy. We demonstrate that hypoxia-induced factor 1α (HIF1α) interaction with HDAC1 and concurrent PRC2 dependency causes chromatin remolding resulting in epigenetic suppression of effector genes and subsequent immune dysfunction. Targeting HIF1α and the associated epigenetic machinery can reverse the immune effector dysfunction and overcome resistance to PD-1 blockade, as demonstrated both in vitro and in vivo using syngeneic and humanized mice models. These findings identify a HIF1α-mediated epigenetic mechanism in immune dysfunction and provide a potential strategy to overcome immune resistance in TNBC.
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