Normal ECG standards and percentile charts for infants, children and adolescents.

BACKGROUND: Normal ECG standards in newborns, infants, children and adolescents have been collected and published by many authors. Only those by Davignon et al., Rijinbeek et al. and our two studies covered all ages from birth to adolescence. The standards reflecting the growth and development of the heart in infants, children and adolescents remained to be studied and explored. METHODS: We selected from our ECG database, after discussions and consultation, 15 key ECG parameters and analyzed for their age- and sex-specific mean, standard deviation and 2nd to 98th percentiles and their percentile charts were constructed. RESULTS: The ranges and distributions of the normal ECG standards, means and 2nd to 98th percentiles of 15 key parameters were established. CONCLUSION: A complete set of normal ECG standards of 15 key parameters from birth to adolescents is available for clinicians and researchers.

Precision Low-Cost Compact Micro-Displacement Sensors Based on a New Arrangement of Cascaded Levers with Flexural Joints.

Existing displacement sensors of micrometers to sub-micron precision are expensive and have various limitations. This paper reports the design and development of a new contact type compact micro-displacement sensor of sub-micron precision for a fraction of the cost of commercial devices. The basic concept of the new sensor system applies a mechanical magnifying mechanism to magnify a displacement at sub-micron to micron level and uses a low-cost Hall sensor to measure the magnified displacement. Various conceptual designs for the mechanical magnifying mechanism based on cascaded levers with flexural joints were studied and a final design, featuring side-by-side placement of lever structures in a multi-planar layout with adjacent levers coupled by L-shaped coupling foils, was devised. Prototypes of two different sizes and constructions with mechanical magnification ratios over 100 were made and tested. Measurement repeatability and accuracy to sub-micrometer level and a resolution down to hundredths of a micrometer were demonstrated by a compact Alpha Model prototype. Design modification of parts and a corresponding small lot size production procedure were devised to provide an estimated bill of material cost per unit under US$100.

How Internal Marketing Drives Employees' Internal Relationship Quality of Service Organizations Between Mainland China and Taiwan: The Moderating Roles of Internal Relationship Investment and Leader-Member Exchange.

Recently, issues of human resource management gradually attract a lot of attention from organizational behavior scholars, thus how to effectively improve service employees' job attitude and performance to meet the needs of stakeholders is one of the key issues in internal marketing. Based on the perspective of internal marketing, the study transforms the relevant factors applied to maintaining external customer relations into internal employee-oriented factors, so as to increase the understanding of the relationship between internal service recovery and internal relationship quality (IRQ). This study aims to explore (1) whether internal service recovery enhances IRQ; (2) whether internal relationship investment (IRI) positively moderates relationship between internal service recovery and IRQ; and (3) whether effectiveness of internal service recovery differentiates under different exchange relationship (high/low quality leader-member exchange). In this study, a total of 206 Mainland China and 250 Taiwanese participants were collected. In this study, a variance-based structural equation modeling (PLS-SEM) was performed to test the proposed hypothesizes and conduct comparative analysis. Empirical results in both samples show that internal service recovery has positive and significant effects on IRQ; internal relationship investment and leader-member exchange (LMX) positively and significantly moderate the relationship between internal service recovery and IRQ. Finally, based on the results, this study provides some discussions, suggestions and managerial implications for future studies in organizational management.

Author Correction: Solution-processed hybrid perovskite photodetectors with high detectivity.

This Article contains an error in Equation 2 in that the denominator is inverted. This has not been fixed in the PDF or HTML versions of the Article but can be seen in the associated Correction.

Study on ECG in the Adolescent.

Normal ECG values in newborns, infants, and children have been collected and published. ECG in the adolescent, however, remains, to be collected and studied. The present study was designed and carried out to establish the normal ECG standards in male and female adolescents. A total of 898 school children and adolescents screened and examined as healthy were divided by age and sex into 6-9, 9-13, and 13-18 years age-groups. A 12 lead conventional ECG was recorded in 10 mm/mV and 25 mm/s, utilizing an automated Fukuda Denshi FCP-4301, MS-DOS/IBM-AT ECG machine. Lead V3R was not taken. Analog-to-digital conversion was performed by Fukuda signal acquisition module at a sampling rate of 500 Hz. The data on 69 ECG parameters were analyzed for the mean, standard deviation, 2nd to 98th percentiles, 95% confidence intervals, and sex difference. Normal values on 69 ECG parameters, sex-specific heart rate, P-QRS-T interval, duration, axis, wave amplitude, and calculated R/S amplitude ratio and ventricular activation time by age-group and sex were established. Male and female difference was noted in 49 (71.0%) parameters, of which 3 (6.1%) began in 6-9 years age-group, 30 (61.2%) began in 9-13 years age-group, and 16 (32.7%) in 13-18 years age-group. No sex difference occurred in 20 (29.0%) parameters. Normal male and female ECG standards on 69 ECG parameters in the adolescent were established. ECG sex difference began to appear the earliest at ages 6-9 years, and it occurred mostly at ages 9-13 years and 13-18 years, reflecting the anatomical and physiological consequences of puberty.

Improved air stability of perovskite solar cells via solution-processed metal oxide transport layers.

Lead halide perovskite solar cells have recently attracted tremendous attention because of their excellent photovoltaic efficiencies. However, the poor stability of both the perovskite material and the charge transport layers has so far prevented the fabrication of devices that can withstand sustained operation under normal conditions. Here, we report a solution-processed lead halide perovskite solar cell that has p-type NiO(x) and n-type ZnO nanoparticles as hole and electron transport layers, respectively, and shows improved stability against water and oxygen degradation when compared with devices with organic charge transport layers. Our cells have a p-i-n structure (glass/indium tin oxide/NiO(x)/perovskite/ZnO/Al), in which the ZnO layer isolates the perovskite and Al layers, thus preventing degradation. After 60 days storage in air at room temperature, our all-metal-oxide devices retain about 90% of their original efficiency, unlike control devices made with organic transport layers, which undergo a complete degradation after just 5 days. The initial power conversion efficiency of our devices is 14.6 ± 1.5%, with an uncertified maximum value of 16.1%.

Perovskite Solar Cells Employing Dopant-Free Organic Hole Transport Materials with Tunable Energy Levels.

Conjugated small-molecule hole-transport materials (HTMs) with tunable energy levels are designed and synthesized for efficient perovskite solar cells. A champion device with efficiency of 16.2% is demonstrated using a dopant-free DERDTS-TBDT HTM, while the DORDTS-DFBT-HTM-based device shows an inferior performance of 6.2% due to its low hole mobility and unmatched HOMO level with the valence band of perovskite film.

Working Mechanism for Flexible Perovskite Solar Cells with Simplified Architecture.

In this communication, we report an efficient and flexible perovskite solar cell based on formamidinium lead trihalide (FAPbI3) with simplified configuration. The device achieved a champion efficiency of 12.70%, utilizing direct contact between metallic indium tin oxide (ITO) electrode and perovskite absorber. The underlying working mechanism is proposed subsequently, via a systematic investigation focusing on the heterojunction within this device. A significant charge storage has been observed in the perovskite, which is believed to generate photovoltage and serves as the driving force for charge transferring from the absorber to ITO electrode as well. More importantly, this simplified device structure on flexible substrates suggests its compatibility for scale-up fabrication, which paves the way for commercialization of perovskite photovoltaic technology.

Solution-processed hybrid perovskite photodetectors with high detectivity.

Photodetectors capture optical signals with a wide range of incident photon flux density and convert them to electrical signals instantaneously. They have many important applications including imaging, optical communication, remote control, chemical/biological sensing and so on. Currently, GaN, Si and InGaAs photodetectors are used in commercially available products. Here we demonstrate a novel solution-processed photodetector based on an organic-inorganic hybrid perovskite material. Operating at room temperature, the photodetectors exhibit a large detectivity (the ability to detect weak signals) approaching 10(14) Jones, a linear dynamic range over 100 decibels (dB) and a fast photoresponse with 3-dB bandwidth up to 3 MHz. The performance is significantly better than most of the organic, quantum dot and hybrid photodetectors reported so far; and is comparable, or even better than, the traditional inorganic semiconductor-based photodetectors. Our results indicate that with proper device interface design, perovskite materials are promising candidates for low-cost, high-performance photodetectors.

An efficient triple-junction polymer solar cell having a power conversion efficiency exceeding 11%.

Tandem solar cells have the potential to improve photon conversion efficiencies (PCEs) beyond the limits of single-junction devices. In this study, a triple-junction tandem design is demonstrated by employing three distinct organic donor materials having bandgap energies ranging from 1.4 to 1.9 eV. Through optical modeling, balanced photon absorption rates are achieved and, thereby, the photo-currents are matched among the three subcells. Accordingly, an efficient triple-junction tandem organic solar cell can exhibit a record-high PCE of 11.5%.

Elucidating double aggregation mechanisms in the morphology optimization of diketopyrrolopyrrole-based narrow bandgap polymer solar cells.

The power conversion efficiency (PCE) of a DPP-based polymer solar cell is significantly improved by using DIO or DCB as processing additives. The discovery that DCB outperforms DIO with a significantly wider solvent mixture operation window suggests different optimization mechanisms. Although both solvent mixture systems involve double aggregation processes, including a similar solution-to-film aggregation, however, two distinct solution-stage aggregations are observed: relatively amorphous polymer aggregates form in the CF-DIO solution, while more crystalline polymer aggregates form in CF-DCB solution.

Tactile-feedback stabilized molecular junctions for the measurement of molecular conductance.

Handling the (AFM) tip: The duration of stable molecular junctions was prolonged using a tactile feedback method in which the operator can sense the force of the AFM tip on the sample surface. The movement of the tip is adjusted accordingly, maintaining a more consistent current (i) and voltage (V), instead of having the tip move at a constant preset speed, as in the conventional setup.

Bilateral stress fractures of the ulna in a young adolescent.

We present a case of bilateral ulnar stress fractures in a young male adolescent (15 years old) due to honour guard training and discuss the possible mechanism of this injury. In addition to acquisition of medical history, physical examination and plain radiography, we performed MRI to exclude pathological causes and confirm the plain radiographic findings, indicating stress reactions. Ulnar stress fractures are bone injuries caused by repetitive muscle pull and the reaction of supporting tissues. In honour guard training, the acceleration due to gravity and chronic torsional stress may also contribute to overloading. Thus, such fractures are best managed by avoiding overloading. In addition, we review the literature on stress fractures of the ulnar shaft to map this special kind of fracture.

Gastric volvulus manifesting as infantile wheezing: a puzzling presentation.

Gastric volvulus is a rare disease in the pediatric population. Its clinical presentation is exceedingly variable, and without a high index of suspicion, delayed or missed diagnosis is not uncommon as illustrated by this report of a 13-month-old boy with a puzzling presentation of chronic wheezing and cough for 1 year. There were no gastrointestinal symptoms. The symptoms were attributed to bronchiolitis, pneumonia, laryngomalacia, or reactive airway disease by several practicing physicians. A detailed history revealed that the wheezing got worse after large meals. This information prompted an upper gastrointestinal contrast study, which led to the identification of organoaxial gastric volvulus and coexisting gastroesophageal reflux. The respiratory symptoms resolved dramatically after antireflux medications and lifestyle modification for gastroesophageal reflux. This report highlights chronic gastric volvulus in the differential diagnosis of infantile wheezing, particularly when the wheezing is present very early in life and associated with feeding.

A salt made of 4-N,N-dimethylaminopyridine (DMAP) and saccharin as an efficient recyclable acylation catalyst: a new bridge between heterogeneous and homogeneous catalysis.

Here, we report insights into the new recyclable catalyst 1, (DMAP·saccharin). The DMAP·saccharin-catalysed acylation of alcohols has been successfully carried out more than 8 times. Only 1 mol% of catalyst 1 efficiently promotes acylation with almost equimolar amounts of acid anhydrides, under both base-free and solvent-free conditions.

5,5'-Bis[(2,2,2-trifluoro-eth-oxy)meth-yl]-2,2'-bipyridine.

The complete molecule of the title compound, C(16)H(14)F(6)N(2)O(2), is generated by crystallographic inversion symmetry, which results in two short intramolecular C-H⋯N hydrogen-bond contacts per molecule. In the crystal, aromatic π-π stacking [centroid-centroid distance = 3.457 (2) Å] and weak C-H⋯π inter-actions occur. A short H⋯H [2.32 (3) Å] contact is present.

Thin film morphologies of pi-conjugated rod-coil block copolymers with thermoresponsive property: a combined experimental and molecular simulation study.

A combined experimental and simulational investigation is performed to study the surface morphologies of polymer films formed by poly[2,7-(9,9-dihexylfluorene)]-b-poly[N-isopropylacrylamide] (PF-b-PNIPAAm) rod-coil block copolymers, where PF possesses pi-pi interactions and PNIPAAm is known to exhibit a coil-to-globule phase transition at T=32 degrees C. Two (PF-b-PNIPAAm) rod-coil block copolymers with different block ratios are synthesized and used to prepare thin films on the quartz glass by physisorption. The surface structures of the thermoresponsive polymer films are found to alter significantly in response to thermostimuli. Small, hemispherical domains of the aggregations of rod-blocks are formed at low temperatures. As the temperature increases, the conformations transform to isolated islands, wormlike structures, or even networklike morphologies depending on the grafting density. These morphological transformations due to temperature variation are consistent with simulation findings. The photophysical properties of PF-b-PNIPAAm films are also found to vary with thermostimuli. The PL spectra reveals that the emission originates from the aggregation of PF blocks and the intensity changes as temperature varies. Our study demonstrates that the surface morphologies and the corresponding photophysical properties of the PF-b-PNIPAAm polymer films can be tuned by thermostimuli.