Multi-microjoule GaSe-based mid-infrared optical parametric amplifier with an ultra-broad idler spectrum covering 4.2-16 {\mu}m

We report a multi-microjoule, ultra-broadband mid-infrared optical parametric amplifier based on a GaSe nonlinear crystal pumped at ~2 {\mu}m. The generated idler pulse has a flat spectrum spanning from 4.5 to 13.3 {\mu}m at -3 dB and 4.2 to 16 {\mu}m in the full spectral range, with a central wavelength of 8.8 {\mu}m. The proposed scheme supports a sub-cycle Fourier-transform-limited pulse width. A (2+1)-dimensional numerical simulation is employed to reproduce the obtained idler spectrum. To our best knowledge, this is the broadest -3 dB spectrum ever obtained by optical parametric amplifiers in this spectral region. The idler pulse energy is ~3.4 {\mu}J with a conversion efficiency of ~2% from the ~2 {\mu}m pump to the idler pulse.Comment: 5 pages, 5 figure

MicroRNA Let-7 in B lymphocyte activation

Over the past twenty years, mounting evidence showed that microRNA (miR) plays indispensable roles in various biological processes including aging process, immune cell responses and metabolic reprogramming through posttranscriptional gene targeting [1]. MiR-encoding genes are distributed in different chromosomes as individual genes or in clusters in human and murine genome [1]. Each miR cluster encodes at least two miRs that sometimes belong to the same family, making it critical to dissect the physiological and pathological roles of each clustered miR vs. the entire gene cluster in a given cellular context, such as B cells. Let-7 was one of the two ancient miRs initially found in C. elegans as a regulator of developmental timing [2]. The Let-7 family has twelve members which are distributed on seven different chromosomes in murine genome. Interestingly, all twelve members share the same “seed sequence”, which is key to the complementation between miR and its target genes [3]. An intriguing question is why evolutionarily there are so many members in the let-7 family sharing the exactly same seed sequence. Do they play individual or redundant roles in various cellular context? Our recent work using transgenic mouse models of different let-7 family members revealed that some let-7 miRs express widely in differentiated immune cells including activated splenic B cells (4). We found that let-7a, let-7d, and let-7f were induced by LPS in splenic B cells, and that the let-7adf cluster inhibited B cell activation, whereas let-7e and let-7g were significantly decreased by LPS [4]. Based on these findings, we speculate that let-7e and let-7g might have unique functions compared to the let-7adf cluster in activated splenic B cells. Future experiments with overexpression or deletion of singular let-7e or let-7g by using engineered mouse models are essential to determine their physiological roles in B cells

What drives renewable energy in the group of seven economies? Evidence from non-parametric panel methods

In the last few decades, the environmental degradation, global warming, and climate change remained the life-threatening issues across the globe. Specifically, the use of non-renewable fossil fuels is regarded as the most significant reason of such inclined issues. However, the policy-makers and scholars are now more concerned about the recovery of environmental quality, where renewable energy is considered as the primary solution to the existing issue. The developed economies and environment related international organizations rapidly enhances the use and promotion of renewable energy after the taking pledge in the Kyoto Protocol Agreement (1997). Nonetheless, the scholars are participating in analyzing the key drivers of renewable energy. Still, the proper drivers of renewable energy are not properly addressed in the existing literature. To fill this gap, current study analyzed the group of seven (G7) economies over the period 1990-2020. Using various panel data techniques such as slope heterogeneity, crosssection dependence, unit root, and cointegration test, the results indicates that the slopes are heterogeneous, and the cross-section dependence, as well as cointegration exists among the panel economies. Besides, the irregular distribution of data leads to the adoption of novel Method of Moments Quantile Regression accommodating four quantiles, i.e., (Q0:25, Q0:50, Q0:75, and Q0:90). The examined results asserted that economic growth and energy efficiency negatively and significantly affects renewable energy consumption (REC). Whereas, developed environmental related technologies, environmental taxes, and composite risk index are positively affecting REC in the study panel. Besides, improved energy efficiency (energy efficiency squared) also contributed to the promotion of renewable energy consumption. The Granger causality test estimates reveals bidirectional and unidirectional causal association between the variables. Based on the empirical results, policies are provided that could help developed economies in the promotion of renewable energy consumption, improve economic growth, and enhances environmental sustainability

A comparative study of reduced graphene oxide modified TiO2, ZnO and Ta2O5 in visible light photocatalytic/photochemical oxidation of methylene blue

Reduced graphene oxide (rGO) was applied to prepare various composites of rGO/photocatalyst of G/TiO2, G/ZnO and G/Ta2O5, using titanium (IV) isopropoxide, Zn powder and commercial Ta2O5 powder as photocatalyst precursors, respectively. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric-differential thermal analysis (TG-DTA) and UV–vis diffuse reflectance (UV–vis DRS) were employed to investigate the crystal structure, morphology, surface groups, rGO loading, and optical properties of the produced composites. The photocatalytic activities of the composites under UV–vis and visible light were studied in degradation of methylene blue (MB). G/Ta2O5 showed an enhanced efficiency under UV–vis irradiation. G/TiO2 demonstrated an effective degradation of MB under visible light. The effects of various oxidants, peroxymonosulfate (PMS), peroxydisulfate (PDS) and hydrogen peroxide (H2O2) on MB degradation were thoroughly investigated. H2O2 was a promising oxidant for promoting MB degradation under visible light. The mechanism of the enhanced efficiency in the system of G/TiO2+ vis + H2O2 was discussed

A mathematical model quantifies proliferation and motility effects of TGF--β\beta on cancer cells

Transforming growth factor (TGF) $\beta$ is known to have properties of both a tumor suppressor and a tumor promoter. While it inhibits cell proliferation, it also increases cell motility and decreases cell--cell adhesion. Coupling mathematical modeling and experiments, we investigate the growth and motility of oncogene--expressing human mammary epithelial cells under exposure to TGF--$\beta$. We use a version of the well--known Fisher--Kolmogorov equation, and prescribe a procedure for its parametrization. We quantify the simultaneous effects of TGF--$\beta$ to increase the tendency of individual cells and cell clusters to move randomly and to decrease overall population growth. We demonstrate that in experiments with TGF--$\beta$ treated cells \textit{in vitro}, TGF--$\beta$ increases cell motility by a factor of 2 and decreases cell proliferation by a factor of 1/2 in comparison with untreated cells.Comment: 15 pages, 4 figures; to appear in Computational and Mathematical Methods in Medicin

Dual mechanisms of posttranscriptional regulation of Tet2 by Let-7 microRNA in macrophages

Tet methylcytosine dioxygenase 2 (Tet2) is an epigenetic regulator that removes methyl groups from deoxycytosine residues in DNA. Tet2-deficient murine macrophages show increased lipopolysaccharide (LPS)-induced and spontaneous inflammation at least partially because Tet2 acts to restrain interleukin (IL)-1β and IL-6 expression in induced cells. MicroRNAs have emerged as critical regulatory noncoding RNAs that tune immune cell responses to physiological perturbations and play roles in pathological conditions in macrophages. To determine if a microRNA played any role in Tet2 activity, we examined the interrelationship of Tet2 action and the let-7 microRNA family, utilizing several let-7 microRNA engineered murine models. We first showed that Tet2, but not Tet3, is a direct target of the let-7a-1/let-7d/let-7f-1 (let-7adf) microRNAs in macrophages. We found that overexpression or deletion of the let-7adf gene cluster causes altered IL-6 induction both in tissue culture cells induced by LPS treatment in vitro as well as in a Salmonella infection mouse model in vivo. Mechanistically, let-7adf promotes IL-6 by directly repressing Tet2 levels and indirectly by enhancing a Tet2 suppressor, the key TCA cycle metabolite, succinate. We found that Let-7adf promotes succinate accumulation by regulating the Lin28a/Sdha axis. We thereby identify two pathways of let-7 control of Tet2 and, in turn, of the key inflammatory cytokine, IL-6, thus characterizing a regulatory pathway in which a microRNA acts as a feedback inhibitor of inflammatory processes