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Phase change thermal management devices including heat pipes and ultra-thin vapor chambers can remove and spread the excess heat from microprocessors more efficiently compared with the conventional heat sinks. However, the capillary and CHF limits of the evaporator section remained a challenge for high heat flux (> 100 Wcm−2) large area (> 5 × 5 mm2) applications. In this study, a hybrid microporous structure consists of copper wire meshes (CWMs) as the liquid delivery routing and copper inverse opals (CIOs) film as the boiling/evaporation platform is proposed. The feasibility of the approach and the design optimization were studied with extensive modeling and CFD simulations. For the experiment setup, the heater and the RTD sensors are fabricated over a Silicon chip using the conventional micro fabrication processes and the micro porous copper film is deposited based on template-assisted electrodeposition, resulting in CIOs structure with average 5 μm pore size, 1 μm neck, and 15 μm thickness. A copper wire mesh structure (500 μm thickness, 0.5 porosity, 71 μm wire diameter) with 4 × 4 tile openings (1 × 1 mm2 area per tile) was fixed over the CIOs film with mechanical constraints. A flow loop and vapor chamber are designed and fabricated to perform capillary boiling experiments in a saturated environment (liquid water and vapor at ∼100°C). The hybrid microporous structure was able to remove over 75 W from the 5 × 5 mm2 heater area (over 300 W cm−2 heat flux) with 9°C super heat resulting in thermal resistance of 0.03 cm2°CW−1 at the CHF. The findings of this study are largely beneficial for the design and fabrication of high performance evaporator wicks and next-generation heat routing technologies.

Two-phase, capillary-fed cooling devices are appealing thermal management technologies due to their potential for high heat transfer performance and ease of system-level integration. While existing evaporative wicking structures such as copper inverse opals (CIOs) and copper wire meshes (CWMs) have shown promise for achieving target heat dissipation rates of 100 Wcm−2 or greater, the reliability of these structures for long-term device operation and optimal capillary-driven boiling performance has not received much attention. To ensure proper functionality of the evaporator wick, the microporous copper structures must retain a hydrophilic contact angle during device operation. Surface oxidation of the copper is a critical degradation mechanism that must be addressed to preserve the integrity of the wick. In this study, we systematically investigate the contact angle change of untreated copper and various copper oxides under different conditions. To avoid the formation of hydrophobic Cu2O, we pre-oxidize the copper micro porous wick to form hydrophilic cupric oxide CuO and study the effect of various thermal and chemical oxidation recipes on the hydrophilicity and morphology of the resulting structures. A chemical oxidation formula is implemented for the creation of a stable superhydrophilic surface at a low temperature (70°C) for copper inverse opals (CIOs) (5 μm pore size) and copper wire meshes (CWMs) (76 μm pore opening). The recipe has been optimized to create nano CuO needles with a length of < 100 nm and keep the necks (∼1 μm diameter) open for better capillary wicking of the working fluid. The findings of this study potentially benefit the development of copper-based capillary-fed cooling devices.

Capillary-fed boiling in microporous copper inverse opals (CIOs) is capable of removing an excess of 1 kW/cm2 at 10–15 °C superheat over small wicking distances ∼ 200 μm. In order to remove heat from large area chips (> 1 cm2), longer capillary wicking distance is desired to reduce the manufacturing complexity of the 3D manifold for liquid delivery and vapor extraction. In this study, we propose graded copper inverse opals (g-CIOs) where smaller pores at the bottom provide high capillary pressure for liquid delivery, while larger pores at the top reduce viscous pressure drop for vapor extraction. This nonhomogeneous wicking material decouples the permeability and capillary pressure in the vertical and lateral directions, resulting in greater CHFs and capillary wicking distances. In this study, we demonstrate the feasibility of fabricating g-CIOs material with up to three different pore diameters (2 μm, 5 μm, and 10 μm) using a multi-step template sintering and copper electrodeposition process. We then leverage and expand upon a well-calibrated experimental model for the prediction of CHF in monoporous CIOs to map the performance metrics for g-CIOs. The model combines a hydraulic resistance network with Darcy’s law and accounts for the nonhomogeneous permeabilities in lateral and vertical directions. Using this model, we study the impact of total wick thickness and graded pore-size combinations on the critical heat fluxes and wicking distances. Our modeling results conclude that a two-layer g-CIOs can potentially reach ∼70% enhancement in the critical heat flux or ∼30% enhancement in the wicking length compared to monoporous CIOs of the same thickness. Our fabrication capability and preliminary modeling results offer the opportunity to design boiling tests with optimized g-CIOs and exploring the potential of dissipating high heat flux for large area cooling applications.

Transforming growth factor β (TGF-β) drives epithelial-mesenchymal transition (EMT), playing vital roles in cancer metastasis. The crosstalk between microRNAs (miRNAs) and TGF-β are frequently observed and involved in TGF-β-induced EMT. Here, we determine that miR-577 is significantly upregulated in gastric cancer (GC). miR-577 expression is positively correlated with GC metastasis status and poor patient prognosis. Functional assays demonstrate that miR-577 promotes metastasis and chemoresistance by inducing EMT and stemness-like properties. Moreover, TGF-β promotes the expression of miR-577, and miR-577 participates TGF-β-mediated cancer metastasis. Mechanistically, TGF-β activates miR-577 via NF-κB-mediated transcription, and miR-577 enhances TGF-β signaling by targeting the serum deprivation protein response (SDPR), which directly interacts with ERK to inactivate the ERK-NF-κB pathway, hence forming a feedback loop to drive tumor metastasis. A plausible mechanism of EMT induction by the TGF-β network is elucidated. Our findings suggest that the TGF-β-miR-577-SDPR axis may be a potential prognostic marker and therapeutic target against cancer metastasis in GC., Luo et al. find that mir-577 can be as a prognostic marker and therapeutic target against cancer metastasis in gastric cancer. TGF-β activates miR-577 via NF-κB-mediated transcription, and miR-577 enhances TGF-β signaling by forming a feedback loop with SDPR-ERK-NF-κB pathway.

BackgroundTemporal interference (TI) stimulation is a new technique of noninvasive brain stimulation. Envelope-modulated waveforms with two high-frequency carriers can activate neurons in target brain regions without stimulating the overlying cortex, which has been validated in mouse brains. However, whether TI stimulation can work on the human brain has not been elucidate.ObjectiveTo assess the effectiveness and safety aspect of the envelope-modulated waveform of TI stimulation on human primary motor cortex (M1).MethodsParticipants attended three sessions of 30-min TI stimulation at 2 mA during a random reaction time task (RRTT) or a serial reaction time task (SRTT). Motor cortex excitability was measured before and after TI stimulation.ResultsIn the RRTT experiment, only 70 Hz TI stimulation had a promoting effect on the reaction time (RT) performance and excitability of the motor cortex compared to sham stimulation. Meanwhile, compared with the sham condition, only 20 Hz TI stimulation significantly facilitated motor learning in the SRTT experiment, which was significantly positively correlated with the increase in motor evoked potential.ConclusionThese results indicate that the envelope-modulated waveform of TI stimulation has a significant promoting effect on human motor functions, experimentally suggesting the effectiveness of TI stimulation in humans for the first time and pave the way for further explorations.

We investigated the effect of curcumin on liver anti-oxidative stress in the type 1 diabetic rat model induced by streptozotocin (STZ). Experimental diabetic rats were induced by STZ intraperitoneally. All rats were fed for 21 days including three groups of control (NC), diabetic model (DC) and curcumin-treated (Cur, 1.5 g/kg by gavage). The results showed that curcumin-treatment significantly decreased the blood glucose and plasma malondialdehyde levels, but significantly increased the plasma superoxide dismutase, glutathione peroxidase and reduced glutathione levels. Curcumin treatment decreased the activity of aldose reductase, but increased the plasma glucose-6-phosphate dehydrogenase, glucose synthetase and glucose-polymerizing activities. Curcumin treatment significantly decreased the protein of protein kinase C (PKC) and poly ADP ribose polymerase (PARP) expression in the Cur group compared with the DC group. Moreover, the sorbitol dehydrogenase activity was significantly decreased and deterred glucose enters into the polyol pathway leading to an increased NADPH content in the Cur group compared with the DC group. Our data provides evidence that oxidative stress in diabetic rats may be attenuated by curcumin by inhibiting polyol pathway associated with down-regulated expression of PKC and PARP, as evidenced by both an increase the antioxidant enzymes levels and glycogen biosynthesis enzymes activities.

The aim of the present study was to determine the effects of curcumin on antioxidants using a rat model of type 1 diabetes. Seven‑week‑old male Sprague‑Dawley rats were injected with Streptozotocin (STZ) intraperitoneally to induce this model, and then treated with 1.0% curcumin (weight ratio) mixed in their diet for 21 days. The present study included three groups: Control group (NC), diabetic rat model group (DC) and a curcumin treated group (Diab‑Cur). The results demonstrated that curcumin treatment markedly decreased the blood glucose levels, plasma malondialdehyde concentration and plasma activity of glutathione peroxidase (GSH‑Px) and catalase (CAT); however, it increased the plasma superoxide dismutase (SOD) and insulin levels. Curcumin treatment increased the expression of the CAT, GSH‑Px, HO‑1 and norvegicus NAD(P)H quinone dehydrogenase 1, and decreased the SOD1 expression, which, led to a diminished oxidative stress status. In addition, curcumin treatment significantly increased the protein expression of Keap1 in the Diab‑Cur group when compared with the DC group, decreased cytosolic concentrations of Nrf2 while increasing nuclear accumulation of Nrf2. The results provide evidence that oxidative stress in the STZ‑induced diabetic rat model may be attenuated by curcumin via the activation of the Keap1‑Nrf2‑ARE signaling pathway, as evidenced by a decrease in the blood glucose concentration and an increase in the transcription of several antioxidant genes.