Activation of store-operated calcium entry in airway smooth muscle cells: insight from a mathematical model

Intracellular dynamics of airway smooth muscle cells (ASMC) mediate ASMC contraction and proliferation, and thus play a key role in airway hyper-responsiveness (AHR) and remodelling in asthma. We evaluate the importance of store-operated entry (SOCE) in these dynamics by constructing a mathematical model of ASMC signaling based on experimental data from lung slices. The model confirms that SOCE is elicited upon sufficient depletion of the sarcoplasmic reticulum (SR), while receptor-operated entry (ROCE) is inhibited in such conditions. It also shows that SOCE can sustain agonist-induced oscillations in the absence of other influx. SOCE up-regulation may thus contribute to AHR by increasing the oscillation frequency that in turn regulates ASMC contraction. The model also provides an explanation for the failure of the SERCA pump blocker CPA to clamp the cytosolic of ASMC in lung slices, by showing that CPA is unable to maintain the SR empty of . This prediction is confirmed by experimental data from mouse lung slices, and strongly suggests that CPA only partially inhibits SERCA in ASMC

Hypoxia Enhances Activity and Malignant Behaviors of Colorectal Cancer Cells through the STAT3/MicroRNA-19a/PTEN/PI3K/AKT Axis

Hypoxia is a typical microenvironment feature in almost all solid tumors and is frequently associated with growth of cancers including colorectal cancer (CRC). This study focuses on the influence of hypoxic microenvironment on the activity of CRC cells and the molecules involved. CRC cells were cultured under hypoxic conditions for 48 h, after which the proliferation, migration, invasion, and epithelial-mesenchymal transition activities of cells were increased. MicroRNA- (miR-) 19a was significantly upregulated in cells after hypoxia exposure according to a microarray analysis. STAT3 was confirmed as an upstream regulator of miR-19a which bound to the promoter region of miR-19a at the 96 bp/78 bp sites, and miR-19a bound to the PTEN mRNA to activate the PI3K/AKT signaling pathway. Hypoxia exposure induced STAT3 phosphorylation and PTEN knockdown in CRC cells. Silencing of STAT3 reduced the hypoxia-induced activity of CRC cells, whereas the malignant behaviors of cells were restored after miR-19a upregulation but blocked after PTEN overexpression. Similar results were reproduced in vivo where downregulation of STAT3 or overexpression of PTEN suppressed tumor growth and metastasis in nude mice. This study demonstrated that hypoxia augments activity and malignant behaviors of colorectal cancer cells through the STAT3/miR-19a/PTEN/PI3K/AKT axis

Morphology and Optical Property of ZnO Nanostructures Grown by Solvothermal Method: Effect of the Solution Pretreatment

Zinc oxide (ZnO) nanostructures with different morphologies such as nanopyramids, nanosheets, and nanoparticles have been grown by a simple solvothermal method. The influence of solution pretreatmentt on the morphology and optical properties of ZnO nanostructures has been studied. The experimental results revealed the morphology of ZnO transformed from nanopyramids or nanosheets to nanoparticles after solution pretreatment. Raman and photoluminescence spectra are recorded to examine the crystallinity and optical property of the samples

Gate-voltage control of angular and spatial shifts for a dielectric slab containing graphene

By theoretically considering a dielectric slab containing graphene, we investigate the effect of the graphene layer on the angular Goos-Hänchen (AGH) shifts and the transverse angular and spatial shifts from the spin-Hall effect of light (SHEL) for the reflection of a light beam. Through manipulating the voltage applied to graphene via an exterior gate, it was found that near the transmission resonance of the slab containing graphene, the giant and tunable AGH shifts and transverse shifts (TS) for both s-polarized and p-polarized waves are present. We also find that near the normal incident angle, the giant and tunable TS from SHEL for both s-polarized and p-polarized waves can occur on the interface containing graphene. It is expected that these phenomena can result in significant interesting and novel applications of graphene in all kinds of optical devices, and more

Dispersion-managed soliton molecules in a near zero-dispersion fiber laser

Physics phenomena of multipulse compounds have enriched the life of ultrashort pulses beyond traditional pulse singlets in passively mode-locked fiber lasers. By developing a near zero-dispersion fiber laser, we report on the generation of dispersion-managed soliton (DMS) molecules. During propagation in the laser cavity, the broadband DMSs experience a breathing process (i.e., periodic compression and stretch of the pulse width), which facilitates various molecule evolutions from pulse singlets. In particular, tightly bound DMS pairs, loosely bound DMS pairs and three-pulse to eleven-pulse molecules are respectively observed. Apart from the aforementioned DMS molecules with equal pulse separations, unequally spaced DMS molecules with different multipulse structures are also obtained, typically including the (2 + 1)-type molecule and the (2 + 3 + 1)-type molecule. The investigation of DMS molecules characterized by versatile multipulse structures is of both fundamental scientific interests in soliton dynamics and potential applications of ultrahigh-capacity optics communications based on advanced modulation formats.Published versio

Nonlinear Fourier transform assisted high-order soliton characterization

Nonlinear Fourier transform (NFT), based on the nonlinear Schrödinger equation, is implemented for the description of soliton propagation, and in particular focused on propagation of high-order solitons. In nonlinear frequency domain, a high-order soliton has multiple eigenvalues depending on the soliton amplitude and pulse-width. During the propagation along the standard single mode fiber (SSMF), their eigenvalues remain constant, while the corresponding discrete spectrum rotates along with the SSMF transmission. Consequently, we can distinguish the soliton order based on its eigenvalues. Meanwhile, the discrete spectrum rotation period is consistent with the temporal evolution period of the high-order solitons. The discrete spectrum contains nearly 99.99% energy of a soliton pulse. After inverse-NFT on discrete spectrum, soliton pulse can be reconstructed, illustrating that the eigenvalues can be used to characterize soliton pulse with good accuracy. This work shows that soliton characteristics can be well described in the nonlinear frequency domain. Moreover, as a significant supplement to the existing means of characterizing soliton pulses, NFT is expected to be another fundamental optical processing method besides an oscilloscope (measuring pulse time domain information) and a spectrometer (measuring pulse frequency domain information)

Vectorial nature in nonlinear multimode interference based ultrafast fiber lasers

Recent research on nonlinear multimode interference (NL-MMI) based mode-locking method provides a new approach for ultrafast all-fiber lasers. Here, we report on the polarization dynamics of group velocity locked vector solitons (GVLVSs) and noise-like vector pulses (NLVPs) in a graded-index multimode fiber (GIMF) based all-fiber laser. Due to the non-polarization sensitive characteristic of the NL-MMI, emitted pulses automatically evolve into the vector multi-pulse complexes constituting two orthogonally polarized components. Beyond the traditional polarization resolved measurement, dispersive Fourier transform (DFT) and polarization beam splitting techniques are jointly adopted to enable insights into the transient polarization dynamics of the vector solitons. It is found in real time that the two orthogonally polarized components oppositely shift their central wavelengths to compensate the polarization dispersion. In addition, stationary and pulsating NLVPs are respectively unfolded by the DFT based polarization resolved measurement. Especially, the pulsating NLVPs before and after polarization resolved measurement are accompanied with the identical periodic spectral breathing process. All these findings reveal the vectorial nature in NL-MMI based ultrafast fiber lasers, as well as highlight the transient polarization dynamics and the long-term pulsation in dissipative systems.Ministry of Education (MOE)National Research Foundation (NRF)Published versionThis work was supported in part by the National Natural Science Foundation of China under Grant 61775067, in part by Singapore National Research Foundation Competitive Research Program (NRF-CRP-18-2017-02), and in part by Singapore Ministry of Education Academic Research Fund Tier 1 (MOE2019-T1-001-111)

Stationary and pulsating vector dissipative solitons in nonlinear multimode interference based fiber lasers

Rapid progress in real-time spectroscopy uncovers the spatio-spectral scenarios of ultrashort pulses in dissipative systems. Varieties of transient soliton dynamics on different timescales have been revealed. Here, we report on an experimental observation of stationary and pulsating vector dissipative solitons in a nonlinear multimode interference (NL-MMI) based fiber laser with net normal dispersion. Polarization non-discrimination of the NL-MMI mode-locking facilitates the dissipative soliton trapping process. Two orthogonally polarized components are coupled together through oppositely shifting their central frequencies to form the group-velocity-locked vector dissipative solitons (GVLVDSs). Dispersive Fourier transform (DFT) based polarization resolved measurement enables insights into the transient polarization dynamics and the long-term evolution. Particularly, both stationary and pulsating GVLVDSs are obtained with appropriate parameter settings. It is found that the quasi-stationary pulsating manner is accompanied with recurrent spectral breathing and energy oscillation; the two orthogonally polarized components possess synchronous pulsating manners due to the cross-phase modulation induced trapping mechanism and the similar formation process. Additionally, chaotic pulsation is also captured in sense that the spectra cannot recover to their original profiles despite of the harmonic energy oscillation. All these findings can enhance our understanding towards soliton pulsation with the freedom of vectorial degree.Ministry of Education (MOE)Published versionMinistry of Education - Singapore (MOE2019-T1-001-111); National Natural Science Foundation of China (61775067, 61775072); Science Fund for Creative Research Groups of the Nature Science Foundation of Hubei (2018CFA004); Major Projects of Technical Innovation of Hubei (2018AAA040); Fundamental Research Funds for the Central Universities (HUST2017KFXKJC002); Science and Technology Program of Shenzhen, China (JCYJ20160531194407693)