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Alanine hydrochloride was prepared from alanine, then its derivative was synthesized by amidation. The structure of the synthesized product was characterized by infrared and 1H nuclear magnetic resonance. The corrosion inhibition effect of alanine and alanine derivative on carbon steel at 30 ℃ in 0.5 mol/L sulfuric acid medium was studied by weight loss method, electrochemical method and scanning electron microscope. The results showed that alanine derivative had better corrosion inhibition than alanine due to the hydrophobic alkane long chain. The weight loss method and electrochemistry showed that the corrosion inhibition rate reached more than 90% at the alanine derivative dosage of 300 mg/L. The adsorption of corrosion inhibitor on carbon steel surface conformed to Langmuir adsorption model. Alanine derivative at low mass concentrations(50-100 mg/L) could inhibit the oxidation of anode metal,which was anode corrosion inhibitor. At higher mass concentrations(200-500 mg/L), the rate of hydrogen evolution reaction at the cathode and metal oxidation reaction at the anode was reduced at the same time, thus reducing the overall corrosion reaction rate, so alanine derivative was a mixed corrosion inhibitor.

Objective To compare and analyze the recommendations for the timing and frequency of home blood pressure monitoring (HBPM) in clinical practice guidelines to help clinicians select the best recommendations and provide suggestions for the development of recommendations in the future. Methods Clinical practice guidelines related to hypertension published in the last five years were systematically searched and screened, and the recommendations for the timing and frequency of HBPM were extracted for statistical analysis. Results A total of 21 guidelines developed by institutions in 16 countries or regions were included, containing recommendations related to the timing and/or frequency of HBPM. For the HBPM timing, all guidelines recommend that blood pressure measurements be taken twice a day, in the morning and evening. In the morning blood pressure should be measured before taking antihypertensive medication (94.4%, 17/18), before breakfast (72.2%, 13/18) and after urination (55.6%, 10/18), while in the evening it should be taken before dinner (50.0%, 8/16), before bedtime (37.5%, 6/16) or 2 hours after dinner (6.3%, 1/16).For HBPM frequency, 9 (40.9%, 9/22) guidelines recommend at least 3 consecutive days of measurement in the week before the visit, and others suggest that measurements should be taken consecutively for at least 4 d (18.2%, 4/22), 5 d (13.6%, 3/22) or 7 d (27.3%, 6/22) days. Conclusions The guidelines of different countries and regions have great differences in recommendations on the timing and frequency of HBPM. It is recommended that future guideline developers develop the best recommendations after a thorough search, evaluation, and synthesis of the evidence, with full consideration of the balance of pros and cons, feasibility, patient preferences and values, as well as the context in which the guidelines are implemented.

A comprehensive evaluation of clinical practice guidelines (CPGs) is essential to measure their quality. This study introduces the function and meaning of the systematic review of CPGs and combs the development and current status of guideline appraisal tools. On this basis, we expound the content and characteristics of the Scientific, Transparent, and Applicable Rankings Tool (STAR) for Guidelines in depth, with the hope of providing reference for the improvement of the compressive guideline assessment system and the development of high-quality guidelines in the future.

The registration of the guidelines is not only the initial step in the development process, but also an important part of the quality control of the guidelines. Thus, we analyzed the establishment and evolution of registration systems, the current state of guideline registration platforms, and the use of the Practice guideline REgistration for transPAREncy(PREPARE), with the goal of improving the transparency and quality of guideline development.

Objective To investigate the current status of evidence of recommendations contained in Chinese clinical practice guidelines published in journals in 2019, so as to provide reference for the use of evidence for Chinese guidelines in the future. Methods We searched and analyzed information on Chinese guidelines published in 2019 with clear recommendations, grading of evidence quality and corresponding instructions of grading, as well as information on citations supporting the recommendations. Results A total of 31 guidelines (29 Chinese guidelines and 2 English guidelines) containing 568 recommendations and 3126 references were included. Each guideline included an average of 18 recommendations. Of these, 2541 references were presented as evidence in the statements of guideline recommendation(such references are referred to as 'evidence' hereafter). The average number of evidence was 82 in each guideline and every recommendation has 4 pieces of evidence. The top three countries where the evidence was from were China (28.8%), the United States (25.9%), and the United Kingdom (7.0%). Only 39.2% (995/2541) of the evidence was published in the last 5 years. The most common type of evidence for guidelines was randomized controlled trials (26.9%). The citation of systematic reviews was only 12.0%. Conclusions Most of the Chinese guidelines published in 2019 did not have clear and unambiguous recommendations. Those guidelines with clear recommendations had incomplete and untimely evidence citations. Guideline developers should strengthen the rational use of currently available research evidence.

The key challenge in the manufacture of advanced high-temperature piezoceramic energy harvesters (HT-PEHs) with excellent electromechanical conversion capability is the development of piezoceramic materials with a large piezoelectric coefficient (d33) and a high depolarization temperature (Td). Herein, a (1 − x − y)BiScO3–xBiYbO3–yPbTiO3 ((1 − x − y)BS–xBY–yPT) ternary perovskite piezoelectric system with a Curie temperature of more than 425 °C is reported. The x/y = 0.01/0.61 ceramic at the morphotropic phase boundary (MPB) displays a large high-temperature d33 value of 665 pC N−1 and a high Td of 348 °C, which are far better than the corresponding values for many existing typical Pb(Zr, Ti)O3- and BS–PT-based perovskite piezoceramics. These remarkable high-temperature piezoelectric properties can be ascribed to vertical MPB and to the improved tetragonal phase structure with its thermally stable domains. Furthermore, the HT-PEH assembled using the 0.38BS–0.01BY–0.61PT MPB specimen demonstrates an excellent power generation capacity under harsh high-temperature conditions at 200–350 °C, and the converted electrical energy can light up commercial light-emitting diodes. The above results demonstrate that (1 − x − y)BS–xBY–yPT are highly competitive potential stock materials for the preparation of PEHs that are suitable for harsh high-temperature environments. [ABSTRACT FROM AUTHOR]

For mode selection in a quantum cascade laser (QCL), we demonstrate an anti-symmetric sampled grating (ASG). The wavelength of the –1-th mode of this laser has been blue-shifted more than 75 nm (∼ 10 cm−1) compared with that of an ordinary sampled grating laser with an emission wavelength of approximately 8.6 μm, when the periodicities within both the base grating and the sample grating are kept constant. Under this condition, an improvement in the continuous tuning capability of the QCL array is ensured. The ASG structure is fabricated in holographic exposure and optical photolithography, thereby enhancing its flexibility, repeatability, and cost-effectiveness. The wavelength modulation capability of the two channels of the grating is insensitive to the variations in channel size, assuming that the overall waveguide width remains constant. The output wavelength can be tailored freely within a certain range by adjusting the width of the ridge and the material of the cladding layer. [ABSTRACT FROM AUTHOR]