Magnetic and Dielectric Switchings Actuated by the Rotation of the Picoline Ligand in an Iron-Based Dinuclear Phase-Transition Complex.

Multifunctional materials with switchable magnetic and dielectric properties are crucial for the development of memory and sensor devices. Herein, we report a methoxy-bridged dinuclear iron-pyridyl complex [Fe2(4-picoline)4(NCS)4(µ-OCH3)2] (1), which shows simultaneous thermal-induced magnetic and dielectric switchings. Within the phase-transition temperature range, both magnetic switching and the dielectric anomaly were detected, in which the thermal hysteresis loops were 23 and 21 K, respectively. Detailed structural analyses revealed that these simultaneous switchings were rooted in the flexible rotatable ligands, which were actuated by readjusting the π-π intermolecular interactions between the pyridine ligands in the trans positions of the metal centers. These results were comprehensively investigated both experimentally and theoretically. This study presents a new guideline to control both the magnetic and dielectric properties of molecular complexes by external stimuli.

Discovery of Kinetic Effect in a Valence Tautomeric Cobalt-Dioxolene Complex.

Two isostructural valence tautomeric (VT) complexes with different critical temperatures were prepared and fully investigated through a series of magnetic, structural, spectral, and differential scanning calorimetry evidence. The kinetic effect in the VT complex was observed for the first time through scan-rate-dependent studies and further validated by annealing tests.

Regulating Spin-State Switching by Integrating Polyoxometalate Anion into Spin Crossover System.

Polyoxometalate (POM) anions were successfully integrated into Fe(II) spin crossover (SCO) system, which demonstrates an effective role in regulating spin-state switching properties. Specifically, three drastically different magnetic behaviors of Fe(II) ion in the identical cation [Fe(bpp)2]2+ were achieved by leveraging [Mo6O19]2-, [Mo8O26]4-, and [Na(Mo8O26)]3-, respectively.

Giant Single-Crystal Shape Transformation with Wide Thermal Hysteresis Actuated by Synergistic Motions of Molecular Cations and Anions.

Manipulating the collective molecular movements to implement macroscopic mechanical response of bulk material is attractive and challenging. Here, an organic-inorganic hybrid single crystal is synthesized, which exhibits a giant macroscopic shape transformation with a remarkable thermal hysteretic feature. The colossal anisotropic shape change, which manifests as an abrupt elongation of ca. 9 % along the crystallographic c-axis and a concomitant contraction of ca. 9 % in a perpendicular direction, is induced by a significant reorientation of imidazolium, accompanied with a substantial configurational variation in CuBr4 2- complex anions. The synergistic motions of both the molecular cations and anions engender a remarkable large thermal hysteresis (>30 K) in the shape transformation of the single crystal, implying that this material may play a role in alternating memory media. Furthermore, due to the stable crystal lattice, a single crystal that demonstrates naked-eye detectable large shape transformation was used as a thermal actuator to spontaneously control an electric circuit by temperature variation.

[Baseline correction of spectrum for the inversion of chlorophyll-a concentration in the turbidity water].

Suspended particle material is the main factor affecting remote sensing inversion of chlorophyll-a concentration (Chla) in turbidity water. According to the optical property of suspended material in water, the present paper proposed a linear baseline correction method to weaken the suspended particle contribution in the spectrum above turbidity water surface. The linear baseline was defined as the connecting line of reflectance from 450 to 750 nm, and baseline correction is that spectrum reflectance subtracts the baseline. Analysis result of field data in situ of Meiliangwan, Taihu Lake in April, 2011 and March, 2010 shows that spectrum linear baseline correction can improve the inversion precision of Chl a and produce the better model diagnoses. As the data in March, 2010, RMSE of band ratio model built by original spectrum is 4.11 mg x m(-3), and that built by spectrum baseline correction is 3.58 mg x m(-3). Meanwhile, residual distribution and homoscedasticity in the model built by baseline correction spectrum is improved obviously. The model RMSE of April, 2011 shows the similar result. The authors suggest that using linear baseline correction as the spectrum processing method to improve Chla inversion accuracy in turbidity water without algae bloom.

LKB1 inhibits proliferation, metastasis and angiogenesis of thyroid cancer by upregulating SIK1.

Purpose: Liver kinase B1 (LKB1), also known as serine/threonine kinase 11, was considered as a tumor suppressor, which exhibited anti-cancer activity in a variety of cancers. However, the effect of LKB1 in thyroid cancer remains unclear. Methods: In the study, MTT assay, colony formation assay, flow cytometry, western blot analysis, wound healing assay, transwell assays, quantitative real-time PCR, HUVEC migration assay, ELISA assay, tube formation assay and nude mice xenograft were used to investigate the anti-cancer capacity of LKB1 in thyroid cancer in vitro and in vivo. Results: In the present study, we found that the expression of LKB1 was lower in thyroid cancer tissues and cell lines, compared with the adjacent normal tissue and thyroid epithelial cell. After construction of stable clone cells with ectopic LKB1 overexpression, the findings revealed that LKB1 overexpression exerted anti-proliferative and pro-apoptotic property in thyroid cancer TPC-1 and BCPAP cells. In addition, LKB1 overexpression could inhibit migration and invasion, downregulate MMP2 and MMP9 expressions, and reverse EMT in thyroid cancer cells. Furthermore, overexpression of LKB1 attenuated HUVEC recruitment, decreased the expression of VEGFA and inhibited the formation of new vessels in thyroid cancer cells. To validate the underlying mechanism of LKB1 in thyroid cancer, the results showed that LKB1 could positively regulate SIK1 in thyroid cancer TPC-1 and BCPAP cells. Additionally, the SIK1 inhibitor HG-9-91-01 could partially abrogate the anti-proliferative and anti-metastatic effect of LKB1, and reverse MET (mesenchymal-to-epithelial transition) mediated by LKB1 overexpression. Ultimately, the results in vivo revealed that LKB1 overexpression exhibited a strong inhibitory effect of tumorigenicity and presented anti-angiogenic characteristic in nude mice xenograft model. Conclusion: the results demonstrated that LKB1 could inhibit proliferation, metastasis phenotype and angiogenesis, and reverse EMT in thyroid cancer in vitro and vivo via the upregulation of SIK1, suggesting that LKB1 could be considered as a potential therapeutic target for the treatment of thyroid cancer.

A homochiral 3D framework of mechanically interlocked 1D loops with solvent-dependent spin-state switching behaviors.

An atypical homochiral spin-crossover (SCO) framework (1) constructed from mechanically interlocked 1D molecular loops was prepared. Due to the flexibility of the interlocked structure, the guest solvent molecules can be reversibly exchanged. Consequently, its SCO behavior was capable of modulating between one- and two-stepped transitions in response to acetonitrile and methanol.

Selective brain hypothermia-induced neuroprotection against focal cerebral ischemia/reperfusion injury is associated with Fis1 inhibition.

Selective brain hypothermia is considered an effective treatment for neuronal injury after stroke, and avoids the complications of general hypothermia. However, the mechanisms by which selective brain hypothermia affects mitochondrial fission remain unknown. In this study, we investigated the effect of selective brain hypothermia on the expression of fission 1 (Fis1) protein, a key factor in the mitochondrial fission system, during focal cerebral ischemia/reperfusion injury. Sprague-Dawley rats were divided into four groups. In the sham group, the carotid arteries were exposed only. In the other three groups, middle cerebral artery occlusion was performed using the intraluminal filament technique. After 2 hours of occlusion, the filament was slowly removed to allow blood reperfusion in the ischemia/reperfusion group. Saline, at 4°C and 37°C, were perfused through the carotid artery in the hypothermia and normothermia groups, respectively, followed by restoration of blood flow. Neurological function was assessed with the Zea Longa 5-point scoring method. Cerebral infarct volume was assessed by 2,3,5-triphenyltetrazolium chloride staining, and apoptosis was assessed by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling staining. Fis1 and cytosolic cytochrome c levels were assessed by western blot assay. Fis1 mRNA expression was assessed by quantitative reverse transcription-polymerase chain reaction. Mitochondrial ultrastructure was evaluated by transmission electron microscopy. Compared with the sham group, apoptosis, Fis1 protein and mRNA expression and cytosolic cytochrome c levels in the cortical ischemic penumbra and cerebral infarct volume were increased after reperfusion in the other three groups. These changes caused by cerebral ischemia/reperfusion were inhibited in the hypothermia group compared with the normothermia group. These findings show that selective brain hypothermia inhibits Fis1 expression and reduces apoptosis, thereby ameliorating focal cerebral ischemia/reperfusion injury in rats. Experiments were authorized by the Ethics Committee of Qingdao Municipal Hospital of China (approval No. 2019008).

Spin crossover and photomagnetic behaviors in one-dimensional looped coordination polymers.

Three one-dimensional looped coordination polymers with the formula of [Fe(dpds)2{C(CN)3}2]·dpds (1, dpds = 4,4'-dipyridyl disulfide), [Fe(dpds)2(NCBH3)2] (2) and [Fe(dpds)2(NCSe)2]·3.5H2O (3) have been synthesized and characterized by single-crystal X-ray crystallography, Mössbauer spectroscopy and magnetic measurements. The spin-crossover (SCO) behaviors of these compounds depend significantly on axial ligands: compound 1 exhibited thermal-induced complete one-step SCO behavior with a T1/2 of 170 K, and 2 showed incomplete SCO behavior with T1/2 being 130 K, whereas 3 was paramagnetic. Meanwhile, both compounds 1 and 2 displayed light-induced excited spin-state trapping (LIESST) effects, featuring TLIESST values of 45 K and 61 K for 1 and 2, respectively, which were independent of exciting laser wavelengths. These results suggest that anions such as C(CN)3- and NCBH3- with much stronger ligand fields are needed in order to realize spin-state switching, if a ligand such as dpds is adopted to synthesize SCO compounds.

Mechanical properties of nasal fascia and periosteum.

OBJECTIVE: To determine under which layer the silicone implants should be inserted into, the biomechanical properties of fascia and periosteum were investigated. DESIGN: Biomechanical testing of cadaveric tissues. BACKGROUND: In silicone augmentation rhinoplasty, most complications are closely related to the depth of implant and the mechanical character of the tissue surrounding the implant. METHODS: Biomechanical properties of human nasal periosteum and fascia were studied, including tensile strength, stress-strain relationship and stress relaxation under uniaxial elongation.Result. Although with less failure strain, the periosteum has more tensile strength than fascia. The slope of the linear part of stress-strain curve of the periosteum is bigger than that of fascia, which indicates the periosteum is stiffer than fascia. The stress-relaxation slope of periosteum is smaller than that of fascia. CONCLUSION: In the view of biomechanics, the periosteum is thicker, stronger and stiffer than fascia. Under periosteum the silicone implants are easier to be fixed at desired position, thus periosteum is more suitable for covering silicone implants. RELEVANCE: The periosteum is more suitable than fascia for covering silicone implants in augmentation rhinoplasty.

[Change trend of vegetation cover in Beijing metropolitan region before and after the 2008 Olympics].

The MODIS-NDVI data from 2000 to 2009 were used to analyze the temporal dynamics and spatial distribution of the vegetation cover in the Beijing metropolitan region before and after the 2008 Olympics. During the study period, the proportion of the significantly increased pixels of NDVI occupied 20.7% while that of the significantly decreased pixels only occupied 4.1% of the total, and the decreasing rate of the NDVI was slightly faster than the increasing rate. The significant changes of the NDVI were mainly concentrated in the low altitude and small slope areas with intensive human activities, and two bands were formed in the plain area, i. e., the vegetation increasing band within the 5th Ring Road and the vegetation decreasing band from the 5th Ring Road to the outside areas of the 6th Ring Road. In the areas with significant vegetation change, there was an obvious transition between the high and low NDVI sections but less change in the medium NDVI section, mainly due to the conversion of land cover type. In the Capital function core area and ecological conservation zones, vegetation change represented a positive trend; while in the urban function expansion area and urban development area, vegetation change had the dual characteristics of both positive and negative trends. A series of ecological engineering projects during the preparatory period of the 2008 Olympics was the main cause of the vegetation increase in the study area.