Some insects, such as dragonflies, have evolved nanoprotrusions on their wings that rupture bacteria on contact. This has inspired the design of antibacterial implant surfaces with insect-wing ...mimetic nanopillars made of synthetic materials. Here, we characterise the physiological and morphological effects of mimetic titanium nanopillars on bacteria. The nanopillars induce deformation and penetration of the Gram-positive and Gram-negative bacterial cell envelope, but do not rupture or lyse bacteria. They can also inhibit bacterial cell division, and trigger production of reactive oxygen species and increased abundance of oxidative stress proteins. Our results indicate that nanopillars' antibacterial activities may be mediated by oxidative stress, and do not necessarily require bacterial lysis.
Epithelial-mesenchymal transition (EMT) is regarded as a crucial contributing factor to cancer progression. Diverse factors have been identified as potent EMT inducers in ovarian cancer. However, ...molecular mechanism sustaining EMT of ovarian cancer cells remains elusive. Here we show that the presence of SOS1/EPS8/ABI1 complex is critical for sustained EMT traits of ovarian cancer cells. Consistent with the role of SOS1/EPS8/ABI1 complex as a Rac1-specific guanine nucleotide exchange factor, depleting Rac1 results in the loss of most of mesenchymal traits in mesenchymal-like ovarian cancer cells, whereas expressing constitutively active Rac1 leads to EMT in epithelial-like ovarian cancer cells. With the aid of clinically tested inhibitors targeting various EMT-associated signaling pathways, we show that only combined treatment of mitogen-activated extracellular signal-regulated kinase 1/2 (MEK1/2) and Src inhibitors can abolish constitutively active Rac1-led EMT and mesenchymal traits displayed by mesenchymal-like ovarian cancer cells. Further experiments also reveal that EMT can be induced in epithelial-like ovarian cancer cells by co-expressing constitutively active MEK1 and Src rather than either alone. As the activities of Erk and Src are higher in ovarian cancer cells with constitutively active Rac1, we conclude that Rac1 sustains ovarian cancer cell EMT through simultaneous activation of MEK1/2 and Src signaling pathways. Importantly, we demonstrate that combined use of MEK1/2 and Src inhibitors effectively suppresses development of intraperitoneal xenografts and prolongs the survival of ovarian cancer-bearing mice. This study suggests that cocktail of MEK1/2 and Src inhibitors represents an effective therapeutic strategy against ovarian cancer progression.
Light harvesting enhancement by slow photons in photonic crystal catalysts or dye-sensitized solar cells is a promising approach for increasing the efficiency of photoreactions. This structural ...effect is exploited in inverse opal TiO2 photocatalysts by tuning the red edge of the photonic band gap to the TiO2 electronic excitation band edge. In spite of many experimental demonstrations, the slow photon effect is not fully understood yet. In particular, observed enhancement by tuning the blue edge has remained unexplained. Based on rigorous couple wave analysis simulations, we quantify light harvesting enhancement in terms of absorption increase at a specific wavelength (monochromatic UV illumination) or photocurrent increase (solar light illumination), with respect to homogeneous flat slab of equivalent material thickness. We show that the commonly accepted explanation relying on light intensity confinement in high (low) dielectric constant regions at the red (blue) edge is challenged in the case of TiO2 inverse opals because of the sub-wavelength size of the material skeleton. The reason why slow photons at the blue edge are also able to enhance light harvesting is the loose confinement of the field, which leads to significant resonantly enhanced field intensity overlap with the skeleton in both red and blue edge tuning cases, yet with different intensity patterns.
Current methods of chemical vapour deposition (CVD) of graphene on copper are complicated by multiple processing steps and by high temperatures required in both preparing the copper and inducing ...subsequent film growth. Here we demonstrate a plasma-enhanced CVD chemistry that enables the entire process to take place in a single step, at reduced temperatures (<420 °C), and in a matter of minutes. Growth on copper foils is found to nucleate from arrays of well-aligned domains, and the ensuing films possess sub-nanometre smoothness, excellent crystalline quality, low strain, few defects and room-temperature electrical mobility up to (6.0±1.0) × 10(4) cm(2) V(-1) s(-1), better than that of large, single-crystalline graphene derived from thermal CVD growth. These results indicate that elevated temperatures and crystalline substrates are not necessary for synthesizing high-quality graphene.
Enzymatic biofuel cells (EBFCs) are known as sustainable energy sources due to the utilization of renewable enzyme biocatalysts and fuels, together with mild working conditions. Remarkably, their ...novel and interesting applications in the fields of implantable energy supply devices and self‐powered biosensor are born and attract extensive attention worldwide. But the transition from fundamental research to practical application is problematic due to low efficiency, poor durability, tricky miniaturization, and so on. So, in addition to a detailed review, whether the full potential of these novel EBFCs‐based applications can be implemented will be clearly stated herein as well. More importantly, the emergences of EBFCs‐based self‐powered therapy systems and EBFCs‐based artificial organ open up more possibilities for the future EBFCs. Such remarkable directions and opportunities of EBFCs will also be prospected in detail.
Enzymatic biofuel cells (EBFCs) exhibit attractive promising in the fields of implantable energy source, artificial organ, self‐powered biosensors, and controllable disease therapy. Herein, the development of EBFCs‐based applications is reviewed in detail, which clearly states the challenges that hamper their final implementation, as well as gives an outlook on the future directions and opportunities of EBFCs.
We measured annual C storage, or net ecosystem production (NEP), from 1999 to 2003 in an aspen-dominated, mixed-deciduous forest in Michigan, USA. Measurements of the annual production of above- and ...below-ground live and dead mass, foliar herbivory, and soil respiration were used to develop biometric estimates of NEP (NEP
B). Eddy-covariance measurements made above the canopy were used to construct meteorological estimates of NEP (NEP
M). Over the 5-year study period, C stored annually in live mass (above- and below-ground wood) averaged 2.13
Mg
C
ha
−1
year
−1, while annual detritus production (fine roots, leaf litter, woody debris) averaged 4.35
Mg
C
ha
−1
year
−1. Fine root inputs were the largest component (41%) of annual net primary production.
The forest was a consistent C sink, with annual NEP ranging from 0.80 to 1.98
Mg
C
ha
−1
year
−1, comparable in magnitude to other eastern North American forests. When annual NEP
B and NEP
M were compared in a given year, they differed from each other by 13–148%. However, when compared over 5 years, these independent estimates of C storage converged to within 1% of each other. Differences between same-year biometric and meteorological NEP estimates were explained in part by a lag between late-season net canopy photosynthesis and C allocated to tree growth the following spring. Weekly assessments of bole radial growth in 2001 and 2002 indicated that woody mass growth began prior to positive net canopy photosynthesis in the spring and that >25% of annual photosynthetic C assimilation occurred after growth had stopped in the autumn. Thus, while the temporal separation between photosynthesis and growth reduced agreement between annual NEP
B and NEP
M estimates, these metrics converged over several years. These results suggest that the allocation of recent photosynthate to storage carbohydrates, rather than to immediate growth, may obscure the relationship between shorter term, annual biometric and meteorological C storage estimates. Moreover, the 5-year convergence of biometric and meteorological NEP estimates serves as an important cross-validation, demonstrating that both approaches can yield accurate forest C storage assessments.
Our previous studies demonstrated that Jab1/Csn5 overexpression is correlated with low survival rates in cancer patients, including nasopharyngeal carcinoma (NPC), breast cancer and hepatocellular ...carcinoma, and contributes to NPC's resistance to radiotherapy and cisplatin by regulating DNA damage and repair pathways. However, the molecular mechanism by which Jab1/Csn5 expression is upregulated in NPCs has yet to be determined. In the present study, we identified the upstream regulator of Jab1/Csn5 expression and demonstrated its role in intrinsic resistance of NPC cells to treatment with cisplatin. Signal transducer and activator of transcription-3 (Stat3) expression correlates with and contributes to Jab1/Csn5 transcription. Consistently, silencing of Stat3 in tumors reduced Jab1/Csn5 expression, thereby sensitizing NPC cells to cisplatin-induced apoptosis both in vitro and in vivo. Mechanistically, Stat3 transcriptionally regulated Jab1/Csn5. Furthermore, high mRNA expression levels of Stat3 or Jab1 in colon cancer, breast cancer and glioblastoma are associated with significantly shorter survival times from the R2 online database. These findings identify a novel Stat3-Jab1/Csn5 signaling axis in cancer pathogenesis with therapeutic and prognostic relevance.
Leaf angle distribution is a key parameter to characterize canopy structure and plays a crucial role in controlling energy and mass balance in soil-vegetation-atmosphere-transfer system. Several leaf ...angle distribution functions found in literature have been proposed to account for the non-random distribution of leaf inclination angle with one or two parameters. In this paper, these leaf angle distribution functions (Beta distribution function, ellipsoidal function, rotated-ellipsoidal function, Verhoef's algorithm and de Wit's functions) were compared with field data collected in the First ISLSCP Field Experiment (FIFE) project and two sites within Ku-ring-gai Chase National Park, Sydney, Australia. All functions performed reasonably well. However, the comparison showed that the two-parameter functions including the Beta distribution function and Verhoef's algorithm commonly were more consistent predictors than one-parameter functions.
G-statistics and
χ
2 test applying to the estimates of leaf angle distribution demonstrated that Beta function presented more robustness over other functions, even the ellipsoidal leaf distribution function which has been widely used. Furthermore, the predictions of leaf angle distribution by these functions were used to calculate extinction coefficient and to separate foliage into sunlit and shaded parts. The results suggested that, ellipsoidal function may be suitable to be retrieved with remotely-sensed data and to compute extinction coefficient and fraction of sunlit foliage because this function requires only a single parameter, namely the ratio of the horizontal semi-axis length to the vertical semi-axis length of an ellipsoid. Finally, the comparison of three approaches (Nilson's, Fuchs’ and Ross–Goudriaan's algorithms) for computing extinction coefficient indicated that, there was no significant difference between the three approaches.
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