Chromium Picolinate Regulates Bone Metabolism and Prevents Bone Loss in Diabetic Rats.

Diabetic osteoporosis (DOP) is an abnormal metabolic disease caused by long-term hyperglycemia. In this study, a model rat of streptozotocin (STZ)-induced diabetes was established, and chromium picolinate (5 mg·kg-1) was given; the changes in blood glucose and body weight were detected before and after administration; and bone mineral density (BMD), bone morphology, bone turnover markers, inflammatory cytokines, and oxidative stress indicators were observed in each group. We found that after chromium picolinate (CP) intervention for 8 weeks, the blood glucose level was decreased; the BMD, the bone histomorphology parameters, and the pathological structure were improved; the expression of bone resorption-related proteins was downregulated; and the expression of bone formation-related proteins was upregulated. Meanwhile, serum antioxidant activity was increased, and inflammatory cytokine levels were decreased. In conclusion, CP could alleviate DOP by anti-oxidation, inhibition of bone turnover, anti-inflammation, and regulation of the OPG/RANKL/RANK signaling pathway. Therefore, CP has important application values for further development as a functional food or active medicine in DOP treatment.

Protective Effect of Black Rice Cyanidin-3-Glucoside on Testicular Damage in STZ-Induced Type 1 Diabetic Rats.

Diabetic testicular damage is quite a common and significant complication in diabetic men, which could result in infertility. The natural fertility rate of type 1 diabetes men is only 50% because of testicular damage. This research first aimed to explore the intervention effect of C3G on testicular tissue damage induced by diabetes. Here, a streptozotocin-induced type 1 diabetic rat model was established, and then C3G was administered. After 8 weeks of C3G supplementation, the symptoms of diabetes (e.g., high blood glucose, lower body weight, polydipsia, polyphagia) were relieved, and at the same time that sperm motility and viability increased, sperm abnormality decreased in C3G-treated diabetic rats. Furthermore, the pathological structure of testis was restored; the fibrosis of the testicular interstitial tissue was inhibited; and the LH, FSH, and testosterone levels were all increased in the C3G-treated groups. Testicular oxidative stress was relieved; serum and testicular inflammatory cytokines levels were significantly decreased in C3G-treated groups; levels of Bax, Caspase-3, TGF-ß1 and Smad2/3 protein in testis decreased; and the level of Bcl-2 was up-regulated in the C3G-treated groups. A possible mechanism might be that C3G improved antioxidant capacity, relieved oxidative stress, increased anti-inflammatory cytokine expression, and inhibited the apoptosis of spermatogenic cells and testicular fibrosis, thus promoting the production of testosterone and repair of testicular function. In conclusion, this study is the first to reveal that testicular damage could be mitigated by C3G in type 1 diabetic rats. Our results provide a theoretical basis for the application of C3G in male reproductive injury caused by diabetes.

Chromium Picolinate Protects against Testicular Damage in STZ-Induced Diabetic Rats via Anti-Inflammation, Anti-Oxidation, Inhibiting Apoptosis, and Regulating the TGF-ß1/Smad Pathway.

Chromium picolinate (CP) is an organic compound that has long been used to treat diabetes. Our previous studies found CP could relieve diabetic nephropathy. Thus, we speculate that it might have a positive effect on diabetic testicular injury. In this study, a diabetic rat model was established, and then the rats were treated with CP for 8 weeks. We found that the levels of blood glucose, food, and water intake were reduced, and body weight was enhanced in diabetic rats after CP supplementation. Meanwhile, in CP treatment groups, the levels of male hormone and sperm parameters were improved, the pathological structure of the testicular tissue was repaired, and testicular fibrosis was inhibited. In addition, CP reduced the levels of serum inflammatory cytokines, and decreased oxidative stress and apoptosis in the testicular tissue. In conclusion, CP could ameliorate testicular damage in diabetic rats, as well as being a potential testicle-protective nutrient in the future to prevent the testicular damage caused by diabetes.

Investigation of Parallel and Orthogonal MIMO Antennas with Two-Notched Structures for Ultra-Wideband Application.

Ultra-wideband (UWB) technology is widely used in many communication scenarios. However, narrowband systems can easily interfere with the UWB system, which generates multipath fading. In order to solve these interferences and meet the design requirements of high isolation of multiple-input multiple-output (MIMO) antennas, two MIMO antennas with double-notch structures are designed. Firstly, two U-shaped slots are etched on the radiating patch and feeder to achieve notch characteristics in WiMAX and ITU bands. Using this antenna element, a two-element antenna is put symmetrically in parallel, and two rectangular branches are loaded to improve the isolation. The size is 0.57λ × 0.32λ × 0.013λ (at 2.5 GHz). Then, a four-element antenna is designed to meet the requirements for another application; here, each element is placed orthogonally to each other, and the isolation is improved through loading a cross-shaped branch in the middle of these elements. The size is 0.57λ × 0.57λ × 0.013λ. Both antenna samples are tested to verify the design. Measurement results show that the working bandwidth is 2.45-14.88 GHz and 2.14-14.95 GHz, the isolation is greater than 17 and 20 dB, and the peak gain is 5.7 and 5.9 dBi for the two- and four-element MIMO antenna, respectively. Compared to the references, the designed antennas have a wider bandwidth and a higher gain and radiation efficiency. They are well-suited for diverse wireless applications.

Spatial patterns of climate change and associated climate hazards in Northwest China.

Northwest China (NWC) is experiencing noticeable climate change accompanied with increasing impacts of climate hazards induced by changes in climate extremes. Towards developing climate adaptation strategies to mitigate the negative climatic impacts on both the ecosystem and socioeconomic system of the region, this study investigates systematically the spatial patterns of climate change and the associated climate hazards across NWC based on high resolution reanalysis climate dataset for the period 1979 to 2018. We find that NWC overall is under a warming and wetting transition in climate with change rate of temperature and precipitation around 0.49 °C/10a and 22.8 mm/10a respectively. Characteristics of climate change over the NWC however vary considerably in space. According to significance of long-term trends in both temperature and aridity index for each 0.1° × 0.1° grids, five types of climate change are identified across NWC, including warm-wetting, warm-drying, warm without wetting, wetting without warming and unchanging. The warm-wetting zone accounts for the largest proportion of the region (41%) and mainly locates in the arid or semi-arid northwestern NWC. Our findings show most region of NWC is under impacts of intensifying heatwave and rainstorm due to significant increases in high temperature extremes and precipitation extremes. The warming but without wetting zone is found under a more severe impact of heatwave, particularly for areas near northern Mount. Qinling and northern Loess Plateau. Areas with stronger wetting trend is suffering more from rainstorm.

Tandem addition of nucleophilic and electrophilic reagents to vinyl phosphinates: the stereoselective formation of organophosphorus compounds with congested tertiary carbons.

Carbon anions formed via the addition of Grignard reagents to SP-vinyl phosphinates were modified with electrophilic reagents to afford organophosphorus compounds with diverse carbon skeletons. The electrophiles included acids, aldehydes, epoxy groups, chalcogens and alkyl halides. When alkyl halides were used, bis-alkylated products were afforded. Substitution reactions or polymerization occurred when the reaction was applied to vinyl phosphine oxides.

Broadband Flexible Microstrip Antenna Array with Conformal Load-Bearing Structure.

To enhance the load-bearing mechanical properties and broadband electromagnetic characteristics of the conformal antenna, a broadband microstrip antenna array with a conformal load-bearing structure is proposed in this paper, which consists of three flexible substrate layers and two honeycomb core layers stacked on each other. By combining the antenna and honeycomb core layer in a structural perspective, the antenna array is implemented in the composition function of surface conformability and load-bearing. Additionally, the sidelobe level of the antenna is suppressed based on the reflection surface loaded. Meanwhile, an equivalent model of a honeycomb core layer has been established and applied in the design of a conformal antenna with a load-bearing structure. The presented model increases the accuracy of simulated results and reduces the memory consumption and time of the simulation. The overall size of the proposed antenna array is 32.84 × 36.65 × 4.9 mm (1.36 λ0 × 1.52 λ0 × 0.2 λ0, λ0 is the wavelength at 12.5 GHz). The proposed antenna element and array have been fabricated and measured in the flat state and under other various bending states. Experiment results show the operating relative bandwidth of the antenna array is 20.68% (11.67-13.76 GHz and 14.33-14,83 GHz) in the flat state. Under different bending conditions, the proposed antenna array covers 24.16% (11.08-14.1 GHz), 23.82% (10.63-13.5 GHz), and 23.12% with 30°, 60°, and 90° in the xoz plane (11.55-14.33 GHz). In terms of mechanical load bearing, the structure has better performance than the traditional single-layer honeycomb core load-bearing structure antenna.

Ice phenology dataset reconstructed from remote sensing and modelling for lakes over the Tibetan Plateau.

The Tibetan Plateau (TP) is a region sensitive to global climate change and has been experiencing substantial environmental changes in the past decades. Lake ice phenology (LIP) is a perceptible indicator reflecting changes of lake thermodynamics in response to global warming. Lake ice phenology over the Tibetan Plateau is however rarely observed and recorded. This research presents a dataset containing 39-year (1978-2016) lake ice phenology data of 132 lakes (each with area >40 km2) over the Tibetan Plateau by combining the strengths of both remote sensing (MOD11A2, MOD10A1) and numerical modelling (air2water). Data validation shows that the ice phenology data derived by our method is highly consistent with that based on existing approaches (with R2 > 0.75 for all phenology index and RMSE < 5d). The dataset is valuable to investigate the lake-atmosphere interactions and long-term hydrothermal change of lakes across the Tibetan Plateau.

The stereoselective conversion of epimerized alkoxyl phosphine-borane to P,C, axial-stereogenic tertiary phosphine via cleavage of P-O bond.

The P-O bond of epimerized alkoxyl phosphine-borane was cleaved by naphthalene-lithium, to form two diastereomers of P-anions in a ratio of 86 : 14, which was then converted to secondary phosphine-borane via acidification, and to tertiary phosphines with alkyl halides with enhanced 96 : 4 dr. The isolated tertiary phosphine containing hydroxyl (in >99 : 1 dr) was converted to multi-stereogenic tertiary phosphines via O-alkylation with alkylene dihalides.

Recent Advances in Copper-Catalyzed C-N Bond Formation Involving N-Centered Radicals.

C-N bonds are pervasive throughout organic-based materials, natural products, pharmaceutical compounds, and agricultural chemicals. Considering the widespread importance of C-N bonds, the development of greener and more convenient ways to form C-N bonds, especially in late-stage synthesis, has become one of the hottest research goals in synthetic chemistry. Copper-catalyzed radical reactions involving N-centered radicals have emerged as a sustainable and promising approach to build C-N bonds. As a chemically popular and diverse radical species, N-centered radicals have been used for all kinds of reactions for C-N bond formation by taking advantage of their inherently incredible reactive flexibility. Copper is also the most abundant and economic catalyst with the most relevant activity for facilitating the synthesis of valuable compounds. Therefore, the aim of the present Review was to illustrate recent and significant advances in C-N bond formation methods and to understand the unique advantages of copper catalysis in the generation of N-centered radicals since 2016. To provide an ease of understanding for the readers, this Review was organized based on the types of nitrogen sources (amines, amides, sulfonamides, oximes, hydrazones, azides, and tert-butyl nitrite).

Recent progress in the radical α-C(sp3)-H functionalization of ketones.

The direct use structurally simple ketones as α-ketone radical sources for α-C(sp3)-H functionalization is a sustainable and powerful approach for constructing complex and multifunctional chemical scaffolds with diverse applications. The reactions of α-ketone radicals with alkenes, alkynes, enynes, imides, and imidazo[1,2-a]pyridines have broadened the structural diversity and complexity of ketones. Through chosen illustrative examples, we outline the recent progress in the development of methods that enable the radical α-C(sp3)-H functionalization of ketones, with an emphasis on radical initiation systems and possible mechanisms of the transformations. The application of these strategies is illustrated by the synthesis of several biologically active molecules and drug molecules. Further subdivision is based on substrate type and reaction type.

Selective divergent radical cyclization of 1,6-dienes with alkyl nitriles.

An efficient, selective, and step economical radical cyclization of 1,6-dienes with alkyl nitriles initiated by α-C(sp3)-H functionalization under the Sc(OTf)3 and Ag2CO3 system is described here. The selective divergent cyclization relies on the substitution effect at the α-position of the acrylamide moiety and nitriles, which is terminated by hydrogen abstraction, direct cyclization with the aryl ring, or further cyclization with the CN bond and hydrolysis, respectively.

The construction of benzimidazo[2,1-a]isoquinolin-6(5H)-ones from N-methacryloyl-2-phenylbenzoimidazoles through radical strategies.

Benzimidazo[2,1-a]isoquinolin-6(5H)-one constitutes a structurally unique class of tetracyclic N-heterocycles that are found throughout a myriad of biologically active natural products, pharmaceutical compounds, and functional materials. Various synthetic routes for the preparation of benzimidazo[2,1-a]isoquinolin-6(5H)-ones have been reported. In particular, the use of N-methacryloyl-2-phenylbenzoimidazoles to construct benzimidazo[2,1-a]isoquinolin-6(5H)-ones through various radical strategies have attracted widespread attention due to the versatility and simple preparation of raw materials, as well as the step-economy and mild reaction conditions. Using representative examples, we highlight significant progress in the synthesis of benzimidazo[2,1-a]isoquinolin-6(5H)-ones, including the selection of the catalytic system, substrate scope, mechanistic understanding, and applications. The contents of this review focus on the development of C-, S-, P-, and Si-centered radical addition-intramolecular cyclization strategies.

ZnO-Co3O4/N-C Cage Derived from the Hollow Zn/Co ZIF for Enhanced Degradation of Bisphenol A with Persulfate.

The zeolitic imidazolate framework (ZIF)-67 microcrystal was employed as a precursor to synthesize the hollow ZIF-8/ZIF-67 composite via the epitaxial growth of ZIF-8 on ZIF-67, in situ self-sacrifice, and excavation of ZIF-67. The hollow ZIF-8/ZIF-67 composite was successfully transformed to the ZnO-Co3O4/N-C cage by thermal treatment, which was further used as the catalyst for the oxidative degradation of bisphenol A (BPA) in the presence of potassium persulfate (PS). In comparison with the Co3O4/N-C and Co3O4 obtained from pure ZIF-67 and cobalt nitrate, the ZnO-Co3O4/N-C cage demonstrated a more than four fold-higher activity and robust reusability. Based on structural analysis, the enhanced catalytic performance could be ascribed to the small, highly dispersed cobalt oxide particles, the hollow structure that facilitated the transportation of the molecules, and the synergistic effect between cobalt oxide and nitrogen-doped carbon in the composite. Besides, the effect of dosage of PS, BPA, and the co-existing components such as chloride ion, methanol, and t-butyl alcohol was carefully investigated to propose the possible mechanism. This study would give new insights into the design of functional composite materials from metal organic frameworks and the development of their application in environmental pollution disposal.

Visible-Light-Catalyzed N-Radical-Enabled Cyclization of Alkenes for the Synthesis of Five-Membered N-Heterocycles.

Five-membered N-heterocycles play an important role in organic synthesis and material chemistry, as they are widespread through pharmaceutical molecules and natural products. Chemists have developed many synthetic strategies for constructing five-membered N-heterocycles from N-centered radicals, but the availability of mild and green methods for these transformations is still limited. The cyclization of visible-light-generated N-centered radicals with alkenes has emerged as a powerful tool to enable these chemical transformations in recent years. Through chosen representative examples, the significant developments in this promising field were outlined, including the selection of catalysts, substrate scope, mechanistic understanding (especially density functional theory calculations), and applications. The contents of this Minireview are categorized by intramolecular cyclization and intermolecular N-centered radical addition/cyclization reactions.

Radical Cyclization of 1,n-Enynes and 1,n-Dienes for the Synthesis of 2-Pyrrolidone.

2-Pyrrolidones have aroused enormous interest as a useful structural moiety in drug discovery; however, not only does their syntheses suffer from low selectivity and yield, but also it requires high catalyst loadings. The radical cyclization of 1,n-enynes and 1,n-dienes has demonstrated to be an attractive method for the synthesis of 2-pyrrolidones due to its mild reaction conditions, fewer steps, higher atom economy, excellent functional group compatibility, and high regioselectivity. Furthermore, radical receptors with unsaturated bonds (i. e. 1,n-enynes and 1,n-dienes) play a crucial role in realizing radical cyclization because of the ability to selectively introduce one or more radical sources. In this review, we discuss representative examples of methods involving the radical cyclization of 1,n-enynes and 1,n-dienes published in the last five years and discuss each prominent reaction design and mechanism, providing favorable tools for the synthesis of valuable 2-pyrrolidone for a variety of applications.

Sulfonyl radical triggered selective iodosulfonylation and bicyclization of 1,6-dienes.

A novel sulfonyl radical triggered selective iodosulfonylation and bicyclization of 1,6-dienes has been described for the first time. High selectivity and efficiency, mild reaction conditions, excellent functional group compatibility, and broad substrate scope are the attractive features of this synthetic protocol, which provides a unique platform for precise radical cyclization.

Enhanced Photodetection Performance of Photodetectors Based on Indium-Doped Tin Disulfide Few Layers.

Two dimensional (2D) tin disulfide (SnS2) has attracted growing interest as a promising high performance photodetector with superior performance such as fast response time, high responsivity, and good stability. However, SnS2-based photodetectors still face great challenges, and the photodetection performance needs to be improved for practical applications. Herein, indium-doped SnS2 (In-SnS2) few layers were exfoliated from CVT-grown single crystals, which were synthesized by chemical vapor transport. Photodetectors based on In-SnS2 few layers were fabricated and detected. Compared with photodetectors based on pristine SnS2, photodetectors based on In-SnS2 few layers exhibited better photodetection performances, including higher responsivities, higher external quantum efficiencies, and greater normalized detectivities. The responsivity (R), external quantum efficiency (EQE), and normalized detectivity (D*) were increased by up to 2 orders of magnitude after In doping. Considering responsivity and response time, the photodetector based on 1.4 at. % In-SnS2 few layers exhibited an optimal photodetection performance with a high R of 153.8 A/W, a high EQE of 4.72 × 104 %, a great D* of 5.81 × 1012 Jones, and a short response time of 13 ms. Our work provides an efficient path to enhance photodetection performances of photodetectors based on SnS2 for future high-performance optoelectronic applications.

An Integrated Mission Planning Framework for Sensor Allocation and Path Planning of Heterogeneous Multi-UAV Systems.

Mission planning is the guidance for a UAV team to perform missions, which plays the most critical role in military and civil applications. For complex tasks, it requires heterogeneous cooperative multi-UAVs to satisfy several mission requirements. Meanwhile, airborne sensor allocation and path planning are the critical components of heterogeneous multi-UAVs system mission planning problems, which affect the mission profit to a large extent. This paper establishes the mathematical model for the integrated sensor allocation and path planning problem to maximize the total task profit and minimize travel costs, simultaneously. We present an integrated mission planning framework based on a two-level adaptive variable neighborhood search algorithm to address the coupled problem. The first-level is devoted to planning a reasonable airborne sensor allocation plan, and the second-level aims to optimize the path of the heterogeneous multi-UAVs system. To improve the mission planning framework's efficiency, an adaptive mechanism is presented to guide the search direction intelligently during the iterative process. Simulation results show that the effectiveness of the proposed framework. Compared to the conventional methods, the better performance of planning results is achieved.

Recent advances in acyl radical enabled reactions between aldehydes and alkenes.

Radical-mediated functionalization of alkenes has been emerging as an elegant and straightforward protocol to increase molecule complexity. Moreover, the abstraction of a hydrogen atom from aldehydes to afford acyl radicals has evolved as a rising star due to its high atom-economy and the ready availability of aldehydes. Considering the great influence and synthetic potential of acyl radical enabled reactions between aldehydes and alkenes, we provide a summary of the state of the art in this field with a specific emphasis on the working models and corresponding mechanisms. The discussion is divided according to the kind of alkenes and reaction type.