Publications

Introduction Ischemia/reperfusion injury (IRI) is a major source of morbidity in liver transplantation and other surgical scenarios. In liver transplantation, IRI contributes to poor outcomes and early graft loss. A better understanding of the mechanisms of hepatic IRI may facilitate the development of new strategies for prevention and treatment. Histone deacetylases (HDACs) regulate diverse cellular processes. In the kidney, class I HDAC inhibition provides protection after ischemia. We sought to delineate the role of HDAC inhibition in mitigating liver ischemia reperfusion injury and other forms of liver injury. Methods Male wild type C57BL/6 (WT) mice were treated with pan-HDAC inhibitor trichostain A (TSA), class I HDAC inhibitor MS-275, HDAC6 inhibitor Tubastatin-A (TubA), Hsp90 inhibitor (17AAG), or control vehicle (DMSO) at 16 and 1 hour pre-IRI. Whole-body tamoxifen-inducible HDAC-1, -2, -6, and -8 deficient and tamoxifen-treated WT male mice were also assessed. Mice were subjected to 70% liver ischemia for 60 minutes under strict temperature control. Histopathologic analysis was conducted at 24 hours post injury, and scored with the Suzuki Score for liver injury. In the acetaminophen (APAP) toxicity experiments, WT mice were treated with vehicle (Tween80, Peg500, and ddH20) or TubA at 16 hours and again just prior to administration of a sublethal dose of APAP (500mg/kg). In both experiments, AST and ALT levels were assessed 24 hours after injury. Results TSA- and TubA-treated mice developed significantly less hepatocellular injury after liver IRI than controls (Fig 1A). H1-/- mice developed significantly less injury after IRI compared to controls, but HDAC6 gene deletion did not mitigate IRI (Fig 1B). HDAC6 inhibition demonstrated decreased histologic liver injury (Figure 1C). TubA also mitigated APAP-induced hepatocellular injury (Fig 1D). Conclusion Pan-HDAC inhibition mitigates liver injury after IRI. Selective inhibition of HDAC1 via inducible gene deletion and pharmacologic inhibition of HDAC6 both replicate this protection. These findings are distinct from the pattern of HDAC involvement in renal IRI and suggest tissue-specific roles for HDACs in IRI response. Pharmacologic inhibition of HDAC6 also mitigated APAP-induced hepatocellular injury suggesting that the protective effects of TubA are not injury-type specific. Further experiments, including mechanistic studies, are required. NIH/NIDDK 1K08DK092282-01.

Fe nanocrystal catalysts were synthesized by electrochemistry. Shape transformations of Fe nanocrystals from rhombic dodecahedra and tetragonal bipyramids, both bounded by {110} facets, to 18-facet polyhedra enclosed by different combinations of {110} and {100} facets and finally to cubes exclusively covered by {100} facets have been achieved. A study of the surface-structure functionality of the Fe nanocrystals toward electroreduction of nitrite revealed that the electrocatalytic activity of the Fe nanocrystals increases as the fraction of {100} facets on the surface of the Fe NCs increases.

Abstract Contact electrification between two different materials is one of the oldest fields of study in solid-state physics. Here, we introduced an innovative system based on optical electric-field-induced second harmonic generation (EFI-SHG) technique that can directly monitor the dynamic performance of the contact electrification on the surface of polyimide film. After the contact, the EFI-SHG system visualized briefly three relaxations of the tribo-induced charges on the surface of a polyimide film, a fast relaxation within 3 min followed by two much slower relaxations, which were possibly related to different charge diffusion routes. The contact electrification under several special experimental conditions (wind, water and steam) was studied to demonstrate the high flexibility and material selectivity of the EFI-SHG. The EFI-SHG studies confirmed the motion of the water can remove the surface charge, while the appearance and the evaporation of a thin water layer cannot enhance the charge diffusion. We anticipate that this experimental technique will find a variety of applications in the field of contact electrification and the development of the recently invented triboelectric nano generator.

We have developed a nanowire nanogenerator that is driven by an ultrasonic wave to produce continuous direct-current output. The nanogenerator was fabricated with vertically aligned zinc oxide nanowire arrays that were placed beneath a zigzag metal electrode with a small gap. The wave drives the electrode up and down to bend and/or vibrate the nanowires. A piezoelectric-semiconducting coupling process converts mechanical energy into electricity. The zigzag electrode acts as an array of parallel integrated metal tips that simultaneously and continuously create, collect, and output electricity from all of the nanowires. The approach presents an adaptable, mobile, and cost-effective technology for harvesting energy from the environment, and it offers a potential solution for powering nanodevices and nanosystems.

Recently, the piezotronic effect has been observed in two-dimensional single-layer MoS2 materials, which have potential applications in force and pressure triggered or controlled electronic devices, sensors, and human-machine interfaces. However, classical theory faces the difficulty in explaining the mechanism of the piezotronic effect for the top- and enclosed-contacted MoS2 transistors, since the piezoelectric charges are assumed to exist only at the edge of the MoS2 flake that is far from the electronic transport pathway. In the present study, we identify the piezoelectric charges at the MoS2/metal-MoS2 interface by employing both the density functional theory and finite element method simulations. This interface is on the transport pathway of both top- and enclosed-contacted MoS2 transistors, thus it is capable of controlling their transport properties. This study deepens the understanding of piezotronic effect and provides guidance for the design of two-dimensional piezotronic devices.

Next Generation EO/IR focal plane arrays using nanostructure materials are being developed for a variety of Defense Applications including Unattended Ground Sensor Applications. These include ZnO nanowires that have demonstrated large signal to noise ratio as a wide band gap nanostructure material in the UV band. Similarly, the work is under way using Carbon Nanotubes (CNT) for a high speed detector and focal plane array as bolometer for IR bands of interest, which can be implemented for the unattended ground sensor applications. In this paper, we will discuss the sensor design and model predicting performance of an EO/IR focal plane array that can cover the UV to IR bands of interest. The model can provide a robust means for comparing performance of the EO/IR FPA's and Sensors that can operate in the UV, Visible-NIR (0.4-1.8μ), SWIR (2.0-2.5μ), MWIR (3-5μ), and LWIR bands (8-14μ). This model can be used as a tool for predicting performance of nanostructure arrays under development. We will also discuss our results on growth and characterization of ZnO nanowires and CNT's for the next generation sensor applications.

Recently, some scholars suggested that it is important to keep a stablehemodynamic state and prevent the stress responses in geriatric patients undergoing total hip replacement (THR). We conducted this randomized prospective study to observe anesthetic potency of unilateral spinal anesthesia and stress response to it in geriatric patients during THR. We compared the effect of unilateral spinal and bilateral spinal on inhibition of stress response through measuring Norepinephrine (NE), epinephrine (E) and cortisol (CORT). Plasma concentrations of NE, E and CORT were determined in blood samples using ELISA (enzyme-linked immunosorbent assays) at three time points: To (prior to anesthesia) T1 (at the time point of skin closure), T2 (twenty-four hours after the operation). Sixty patients were randomly divided into two groups: group A (unilateral spinal anesthesia) and group B (conventional bilateral spinal anesthesia). 7.5tymg of hypobaric bupivacaine were injected into subarachnoid cavity at group A and 12mg hypobaric bupivacaine were given at group B. The onset time of sensory and motor block, loss of pinprick sensation, degree of motor block, regression of sensory and motor blocks and hemodynamic changes were also recorded. These data were used to evaluate anesthetic potency of spinal anesthesia. The results of this experiment show that unilateral spinal anesthesia can provide restriction of sensory and motor block, minimize the incidence of hypotension and prevent the stress responses undergoing THR. It is optimal anesthesia procedure for geriatric patients by rapid subarachnoid injection of small doses of bupivacaine.