Hexamethyldisilazane-Mediated Amidination of Sulfonamides and Amines with Formamides.

Hexamethyldisilazane was reacted with formamides to generate N,N-disubstituent formimidamide, after which a reaction with sulfonamides was induced to form sulfonylformamidines. This protocol can be applied for arylformamidine formation in which anilines are used as substrates under optimized conditions. The advantages of this method are high efficiency, structural diversity in products with good yields, and applicability in large-scale operations.

Rainfall variations in central Indo-Pacific over the past 2,700 y.

Tropical rainfall variability is closely linked to meridional shifts of the Intertropical Convergence Zone (ITCZ) and zonal movements of the Walker circulation. The characteristics and mechanisms of tropical rainfall variations on centennial to decadal scales are, however, still unclear. Here, we reconstruct a replicated stalagmite-based 2,700-y-long, continuous record of rainfall for the deeply convective northern central Indo-Pacific (NCIP) region. Our record reveals decreasing rainfall in the NCIP over the past 2,700 y, similar to other records from the northern tropics. Notable centennial- to decadal-scale dry climate episodes occurred in both the NCIP and the southern central Indo-Pacific (SCIP) during the 20th century [Current Warm Period (CWP)] and the Medieval Warm Period (MWP), resembling enhanced El Niño-like conditions. Further, we developed a 2,000-y-long ITCZ shift index record that supports an overall southward ITCZ shift in the central Indo-Pacific and indicates southward mean ITCZ positions during the early MWP and the CWP. As a result, the drying trend since the 20th century in the northern tropics is similar to that observed during the past warm period, suggesting that a possible anthropogenic forcing of rainfall remains indistinguishable from natural variability.

Dual-functional gold-iron oxide core-satellite hybrid nanoparticles for sensitivity enhancement in biosensors via nanoplasmonic and preconcentration effects.

A common strategy to improve the sensitivity of a biosensor for the detection of a low abundance analyte is to preconcentrate the analyte molecules before detection. A dual-functional gold-iron oxide core-satellite hybrid nanoparticle structure is proposed in this work to overcome the drawbacks of traditional sample pretreatment methods and the methods using non-magnetic nanomaterials for sample pretreatment. The new dual-functional hybrid nanoparticle structure can simultaneously serve as a signal reporter of a biorecognition event and a preconcentrator of a target at an extremely low concentration in a nanoplasmonic biosensor. By utilizing a fiber optic nanogold-linked sorbent assay in the fiber optic particle plasmon resonance (FOPPR) biosensor and an arbitrary DNA sequence as a target, we have demonstrated that the use of the new hybrid nanoparticle structure with magnetic preconcentration improves the limit of detection (LOD) for the DNA by 18 times as compared to the same method without magnetic preconcentration, so that the LOD for detecting the DNA can be as low as 2.6 fM. The new hybrid nanoparticle structure is easy to prepare and its use in the high-sensitivity and low-cost FOPPR biosensor provides vast opportunities in point-of-care applications.

Multidecadally resolved polarity oscillations during a geomagnetic excursion.

Polarity reversals of the geomagnetic field have occurred through billions of years of Earth history and were first revealed in the early 20th century. Almost a century later, details of transitional field behavior during geomagnetic reversals and excursions remain poorly known. Here, we present a multidecadally resolved geomagnetic excursion record from a radioisotopically dated Chinese stalagmite at 107-91 thousand years before present with age precision of several decades. The duration of geomagnetic directional oscillations ranged from several centuries at 106-103 thousand years before present to millennia at 98-92 thousand years before present, with one abrupt reversal transition occurring in one to two centuries when the field was weakest. These features indicate prolonged geodynamo instability. Repeated asymmetrical interhemispheric polarity drifts associated with weak dipole fields likely originated in Earth's deep interior. If such rapid polarity changes occurred in future, they could severely affect satellites and human society.

Controlled hydrothermal synthesis of BiOxCly/BiOmBrn/g-C3N4 composites exhibiting visible-light photocatalytic activity.

The first systematic synthesis of bismuth oxychloride/bismuth oxybromide/graphitic carbon nitride (BiOxCly/BiOmBrn/g-C3N4) nano-composites used a controlled hydrothermal method. The structure, morphology and characteristic of BiOxCly/BiOmBrn/g-C3N4 photocatalyst were measured by XRD, UV-vis-DRS, FT-IR, FE-TEM, FE-SEM-EDS, PL, BET, HR-XPS and EPR. Under visible light irradiation, the photodegradation activity was evaluated for the decolorization of crystal violet (CV) and 2-hydroxybenzoic acid (2-HBA) in aqueous solution. The catalytic performance showed that, when using sample BB2C1-4-250-30 wt% g-C3N4 composite as a photocatalyst, the best reaction-rate-constant (k) was 0.071 h-1. It was 1.5 times higher than the k value of BB2C1-4-250 as a photocatalyst. From the scavenging effect of various scavengers, the results of EPR showed that reactive OH was the main scavenger, while O2-, h+ and 1O2 were the second scavenger in CV degradation. In this study, a possible photodegradation mechanism was proposed and discussed. In this work, our method of BiOxCly/BiOmBrn/g-C3N4 preparation could be used for future mass production and the BiOxCly/BiOmBrn/g-C3N4 composite materials could be applied to the environmental pollution control in future.

Steep Switching of In0.18Al0.82N/AlN/GaN MIS-HEMT (Metal Insulator Semiconductor High Electron Mobility Transistors) on Si for Sensor Applications †.

InAlN/Al/GaN high electron mobility transistors (HEMTs) directly on Si with dynamic threshold voltage for steep subthreshold slope (<60 mV/dec) are demonstrated in this study, and attributed to displacement charge transition effects. The material analysis with High-Resolution X-ray Diffraction (HR-XRD) and the relaxation by reciprocal space mapping (RSM) are performed to confirm indium barrier composition and epitaxy quality. The proposed InAlN barrier HEMTs exhibits high ON/OFF ratio with seven magnitudes and a steep threshold swing (SS) is also obtained with SS = 99 mV/dec for forward sweep and SS = 28 mV/dec for reverse sweep. For GaN-based HEMT directly on Si, this study displays outstanding performance with high ON/OFF ratio and SS < 60 mV/dec behaviors.

Reliance on Visual Input for Balance Skill Transfer in Older Adults: EEG Connectome Analysis Using Minimal Spanning Tree.

Skill transfer from trained balance exercises is critical to reduce the rate of falls in older adults, who rely more on vision to control postural responses due to age-dependent sensory reweighting. With an electroencephalography (EEG) minimum spanning tree (MST) structure, the purpose of this study was to compare the organization of supraspinal neural networks of transfer effect after postural training using full and intermittent visual feedbacks for older adults. Thirty-two older adults were randomly assigned to the stroboscopic vision (SV) (n = 16; age = 64.7 ± 3.0 years) and control (16; 66.3 ± 2.7 years) groups for balance training on a stabilometer (target task) with on-line visual feedback. Center-of-pressure characteristics and an MST-based connectome of the weighted phase-lag index during the bilateral stance on a foam surface (transfer task) were compared before and after stabilometer training. The results showed that both the SV and control groups showed improvements in postural stability in the trained task (p < 0.001). However, unlike the control group (p = 0.030), the SV group who received intermittent visual feedback during the stabilometer training failed to reduce the size of postural sway in the anteroposterior direction of the postural transfer task (unstable stance on the foam surface) in the post-test (p = 0.694). In addition, network integration for the transfer task in the post-test was absent in the SV group (p > 0.05). For the control group in the post-test, it manifested with training-related increases in leaf fraction in beta band (p = 0.015) and maximum betweenness in alpha band (p = 0.018), but a smaller diameter in alpha (p = 0.006)/beta (p = 0.021) bands and average eccentricity in alpha band (p = 0.028). In conclusion, stabilometer training with stroboscopic vision impairs generalization of postural skill to unstable stance for older adults. Adequate visual information is a key mediating factor of supraspinal neural networks to carry over balance skill in older adults.

Novel indole-based peroxisome proliferator-activated receptor agonists: design, SAR, structural biology, and biological activities.

The synthesis and structure-activity relationship studies of novel indole derivatives as peroxisome proliferator-activated receptor (PPAR) agonists are reported. Indole, a drug-like scaffold, was studied as a core skeleton for the acidic head part of PPAR agonists. The structural features (acidic head, substitution on indole, and linker) were optimized first, by keeping benzisoxazole as the tail part, based on binding and functional activity at PPARgamma protein. The variations in the tail part, by introducing various heteroaromatic ring systems, were then studied. In vitro evaluation led to identification of a novel series of indole compounds with a benzisoxazole tail as potent PPAR agonists with the lead compound 14 (BPR1H036) displaying an excellent pharmacokinetic profile in BALB/c mice and an efficacious glucose lowering activity in KKA(y) mice. Structural biology studies of 14 showed that the indole ring contributes strong hydrophobic interactions with PPARgamma and could be an important moiety for the binding to the protein.

Lead isotope characterization of petroleum fuels in Taipei, Taiwan.

Leaded gasoline in Taiwan was gradually phased out from 1983 to 2000. However, it is unclear whether unleaded gasoline still contributes to atmospheric lead (Pb) exposure in urban areas. In this study, Pb isotopic compositions of unleaded gasolines, with octane numbers of 92, 95, 98, and diesel from two local suppliers in Taipei were determined by multi-collector inductively coupled plasma mass spectrometry with a two-sigma uncertainty of ± 0.02 %. Lead isotopic ratios of vehicle exhaust (²°8Pb/²°7Pb: 2.427, ²°6Pb/²°7Pb: 1.148, as estimated from petroleum fuels) overlap with the reported aerosol data. This agreement indicates that local unleaded petroleum fuels, containing 10-45 ng·Pb·g⁻¹, are merely one contributor among various sources to urban aerosol Pb. Additionally, the distinction between the products of the two companies is statistically significant in their individual ²°8Pb/²°6Pb ratios (p-value < 0.001, t test). Lead isotopic characterization appears to be applicable as a "fingerprinting" tool for tracing the sources of Pb pollution.

Prevalence and effectiveness of laxative use among elderly residents in a regional hospital affiliated nursing home in hsinchu county.

BACKGROUND: Long-term care residents are susceptible to constipation and one-half to three quarter of older nursing home residents receive laxatives regularly. OBJECTIVES: The purpose of this study was to evaluate the factors related to abnormal bowel function and explore the effectiveness of laxative treatment among the elderly residents of a nursing home. PATIENTS AND METHODS: A total of 110 residents older than 65 years old was enrolled in this study. The following variables were gathered: age, gender, body mass index (BMI), length of stay, daily fluid intake, type of food, functional level, cognitive ability, physical therapy status, somatic and psychiatric diseases, number of medications, and medication use. The use and dosage of laxatives were recorded by means of Anatomical Therapeutic Chemical (ATC) classification system. Normal bowel function was defined as defecation frequency from three defecations per day to three defecations per week and stool consistency score of three to five on Bristol Stool Form Scale. A comparison between groups with normal and abnormal bowel function was drawn. RESULTS: Low BMI, increased fluid intake, liquid food intake, poor functional level, poor cognition, and a history of stroke were significantly associated with altered bowel function (P < 0.05). The most frequently used laxatives were glycerol, senna glycoside, and magnesium oxide. There were significant differences in laxative regimens between residents with normal and altered bowel function; those with altered bowel function tended to take more laxatives than those with normal bowel function. CONCLUSIONS: This study suggested that treatment of constipation in the nursing home was unsatisfactory. To improve treatment outcomes in those susceptible to altered bowel function, a coordinated approach with involvement of physicians, nursing staff, and other professionals including dieticians and pharmacists seems necessary.