Assessment of Efficacy of Various Bracket Base Retention Qualities on Shear Bond Strength.

Introduction: Numerous manufacturers have improved bracket retention systems as a result of the frequent bond failure that occurs during orthodontic treatment. One of the elements affecting the adhesive's bond strength is the bracket retention mechanism. Objectives: This study's objective was to assess how various bracket base retention characters affected shear bond strength. Materials and Methods: Four distinct base features for brackets were evaluated. The basic design was examined using a scanning electron microscope. On the Universal testing equipment, brackets were glued to human teeth and then released. Results: The findings indicate that the polymer-coated base's overall mean SBS, which had a mean value of 21.64 ± 4.14 MPa, was considerably greater than that of the other brackets (P 0.05). The foil meshpad, photochemically etched base, and laser-structured base had mean SBS values of 15.12 ± 5.75 MPa, 16.86 ± 3.76 MPa, and 19.32 ± 4.23MPa, respectively. Conclusions: Following laser-structured base and photochemically etched base brackets in terms of shear bond strength were polymer-coated base brackets. The shear bond strength was the lowest in the plain foil mesh pads.

Split application of polymer-coated urea combined with common urea improved nitrogen efficiency without sacrificing wheat yield and benefits while saving 20% nitrogen input.

Controlled-release nitrogen fertilizer (CRNF) has been expected to save labor input, reduce environmental pollution, and increase yield in crop production. However, the economic feasibility is still controversial due to its high cost. To clarify the suitable application strategy of CRNF in promoting the yield, nitrogen use efficiency and income on wheat grown in paddy soil, four equal N patterns were designed in 2017-2021 with polymer-coated urea (PCU) and common urea as material, including PCU applied once pre-sowing (M1), PCU applied 60% at pre-sowing and 40% at re-greening (M2), 30% PCU and 30% urea applied at pre-sowing, 20% PCU and 20% urea applied at re-greening (M3), and urea applied at four stage (CK, Basal:tillering:jointing:booting=50%:10%:20%:20%). In addition, M4-M6, which reduced N by 10%, 20% and 30% respectively based on M3, were designed in 2019-2021 to explore their potential for N-saving and efficiency-improving. The results showed that, compared with CK, M1 did not significantly reduce yield, but decreased the average N recovery efficiency (NRE) and benefits by 1.63% and 357.71 CNY ha-1 in the four years, respectively. M2 and M3 promoted tiller-earing, delayed the decrease of leaf area index (LAI) at milk-ripening stage, and increased dry matter accumulation post-anthesis, thereby jointly increasing spike number and grain weight of wheat, which significantly increased yield and NRE compared with CK in 2017-2021. Due to the savings in N fertilizer costs, M3 achieved the highest economic benefits. With the 20% N reduction, M5 increased NRE by 16.95% on average while decreasing yield and net benefit by only 6.39% and 7.40% respectively, compared with M3. Although NRE could continue to increase, but the yield and benefits rapidly decreased after N reduction exceeds 20%. These results demonstrate that twice-split application of PCU combined with urea is conducive to achieving a joint increase in yield, NRE, and benefits. More importantly, it can also significantly improve the NRE without losing yield and benefits while saving 20% N input.

Global impact of enhanced-efficiency fertilizers on vegetable productivity and reactive nitrogen losses.

Vegetables are the most consumed non-staple food globally, and their production is crucial for dietary diversity and public health. Use of enhanced-efficiency fertilizers (EEFs) in vegetable production could improve vegetable yield and quality while reducing reactive nitrogen (Nr) losses. However, different management and environmental factors has significantly distinctive impacts on the effectiveness of EEFs. In this study, a worldwide meta-analysis based on the data collected from 144 studies was performed to assess the impacts of EEF (nitrification inhibitor [NI] and polymer-coated urea [PCU]) application on vegetable yield, nitrogen (N) uptake, nitrogen use efficiency (NUE), vegetable quality and Nr losses (nitrous oxide [N2O] emissions, ammonia [NH3] volatilization, and nitrate [NO3-] leaching). The effects of the applied EEFs on vegetable yields and N2O emissions were assessed with different management practices (cultivation system, vegetable type and N application rate) and environmental conditions (climatic conditions and soil properties). Compared to conventional fertilizers, EEFs significantly improved vegetable yield (7.5-8.1 %) and quality (vitamin C increased by 10.7-13.6 %, soluble sugar increased by 9.3-10.9 %, and nitrate content reduced by 17.2-25.1 %). Meanwhile, the application of EEFs demonstrated a great potential for Nr loss reduction (N2O emissions reduced by 40.5 %, NO3- leaching reduced by 45.8 %) without compromising vegetable yield. The NI was most effective in reducing N2O emissions (40.5 %), but it significantly increased NH3 volatilization (32.4 %). While PCU not only significantly reduced N2O emissions (24.4 %) and NO3- leaching (28.7 %), but also significantly reduced NH3 volatilization (74.5 %). And N application rate, soil pH, and soil organic carbon (SOC) were the main factors affecting the yield and environmental effects of EEFs. Moreover, the yield-enhancing effect of NI and PCU were better at low soil N availability and SOC, respectively. Thus, it is important to adopt the appropriate EEF application strategy targeting specific environmental conditions and implement it at the optimal N application rate.

The Excellent Mechanical Performance of Polymer-Coated Ceramsite Particles for Efficient Fracturing: An Explanation from a Surface, Tribological Perspective.

Hydraulic fracturing using micro-particles is an effective technology in the petroleum industry since the particles facilitate crack propagation of the shale layer, creating pathways for oil and gas. A new kind of polymer-coated ceramsite particles (PCP) was generated. The friction and wear properties of the particles under different loads and speeds were also studied. The tribological relationship between the newly fabricated polymer-coated ceramsite particles and the fracturing fluid was studied through tribological experiments under the condition of fracturing fluid lubrication. The results show that, in contrast, the wear of the new-generation particles is relatively stable, indicating that it has good adjustable friction properties. In addition, under the lubrication condition of fracturing fluid, the new-generation particles have better hydrophobicity, high-pressure resistance, and low reflux rate, which have an important value as a practical engineering application for improving shale gas production efficiency and production.

Trace polymer coated clarithromycin spherulites: Formation mechanism, improvement in pharmaceutical properties and development of high-drug-loading direct compression tablets.

Clarithromycin (CLA) is a high dose antibiotic drug exhibiting poor flowability and tabletability, making the tablet development challenging. This study aims to develop spherulitic CLA by introducing trace amount of polymer in crystallization solution. Its formation mechanism, physicochemical properties and potential for the direct compression (DC) tablets development were also investigated. Morphological analyses and the in situ observation on crystallization process revealed that the CLA spherulites are formed by fractal branching growth from both sides of the threadlike precursor fibers. 1H NMR analysis and nucleation time monitoring indicated that the existence of hydroxypropyl cellulose in solution slowed down the crystal nucleation and growth rate by forming hydrogen bonding interactions with CLA molecules, making the system maintain high supersaturation, providing high driving forces for CLA spherulitic growth. In comparison to commercial CLA, the CLA spherulites exhibit profoundly improved flowability, tabletability and dissolution behaviors. XPS, contact angle and Raman mapping analysis confirmed the presence of a thin HPC layer on the surfaces and interior of CLA spherulitic particles, resulting in increasing powder plasticity, interparticulate bonding strength and powder wettability, thus better tabletability and dissolution performances. The improved flowability and tabletability of CLA spherulites also enabled the successful development of DC tablet formulation with a high CLA loading (82.8 wt%) and similar dissolution profiles to reference listed drug. This study provides a novel solid form of CLA with superior manufacturability for further development.

Soil solution and plant nitrogen on irrigated rice under controlled release nitrogen fertilizers / Nitrogênio na solução do solo e em plantas de arroz irrigado sob adubação com fertilizantes nitrogenados de liberação controlada

ABSTRACT: A study was conducted to evaluate the solubilization and nitrogen (N) use efficiency (NUE) of controlled release nitrogen fertilizers in irrigated rice, compared to urea. It was developed under semi-controlled conditions, including five treatments: Control, Splitted Urea (pre-sowing and topdressing), Pre-sowing urea, and Polymer Coated Urea (PCU) with 60-day and 90-day release. PCUs did not maintain high NH4 + and NO3 - levels in solution over a longer period than urea. NUE of PCUs was similar to uncoated urea, not increasing nutrient release in irrigated rice field.

RESUMO: Realizou-se um trabalho para avaliar a solubilização e eficiência de uso de nitrogênio (N) de fertilizantes nitrogenados de liberação controlada em arroz irrigado, comparando-os à ureia. O experimento foi realizado sob condições semi-controladas, incluindo os tratamentos: Testemunha, Ureia aplicada de forma parcelada, Ureia aplicada em pré-semeadura e Ureia Recoberta por Polímeros (URP) com tempo de liberação de N de 60 e 90 dias, aplicada em pré-semeadura. As URPs não mantiveram os teores de amônio e nitrato em solução por período superior ao da ureia. A eficiência de uso de N das URPs avaliadas foi semelhante à da ureia não recoberta, não aumentando o tempo de liberação do nutriente em cultivo de arroz irrigado.

Fertilizers with coated urea in upland rice production and nitrogen apparent recovery / Doses de fertilizantes com ureia revestida na produção de arroz de terras altas e recuperação aparente de nitrogênio

Urea is the most used N fertilizer for upland rice, however, a great percentage of N loss can occur with the use of this fertilizer. The use of products that provide reduction of N loss for urea fertilizers can contribute to increase N use efficiency. The objective of this study was to determine the effect of N rates applied in the form of coated urea in the content and accumulation of N in dry biomass, apparent recovery of nitrogen and grain yield of upland rice. The experimental design was a randomized complete blocks arranged in a 4 x 3 + 1 factorial scheme. The treatments consisted of four sources of N fertilizer [1. Common urea; 2. Polymer-coated urea for slow release of N (PCU); 3. urea with the urease inhibitor N-(n-Butyl) thiophosphoric triamide (NBPT); and 4. urea coated with copper sulfate and boric acid as urease inhibitors (UCCB)], with three fertilization rates (30, 60 and 90 kg ha-1 of N). In addition, we included a control treatment without N application. Coated urea did not provide increases in rice grain yield in relation to common urea. The increasing amount of N resulted in significant increases in rice grain yield (from 3217 to 5548 kg ha-1, 2010/11, and from 3392 to 4560 kg ha-1, 2011/12). The apparent nitrogen recovery rate decreased with the increase in N applied doses.

A ureia é o fertilizante nitrogenado mais utilizado para o arroz de terras altas, no entanto, esse fertilizante tem grande percentual de perda de N. O uso de produtos que proporcionam redução da perda de N em fertilizantes com ureia pode contribuir para aumentar a eficiência de uso do nitrogênio. O objetivo deste estudo foi determinar o efeito de doses de N aplicadas na forma de ureia encapsulada no teor e acúmulo de N na biomassa seca, recuperação aparente de nitrogênio e produtividade de grãos de arroz de terras altas. O delineamento experimental foi em blocos ao acaso no esquema fatorial 4 x 3 + 1. Os tratamentos consistiram de quatro fontes de N fertilizante [1. ureia tradicional; 2. Polímero de ureia revestida para liberação lenta de N (PCU); 3. ureia com o inibidor de urease N- (n-butil) triamida tiofosfórico (NBPT); e 4. ureia revestida com sulfato de cobre e ácido bórico como inibidores de urease (UCCB)], com três doses de fertilizante (30, 60 e 90 kg ha-1 de N). Além disso, incluímos uma testemunha sem aplicação de N. Ureia revestida não forneceu aumentos no rendimento de grãos de arroz em relação à ureia comum. O aumento da quantidade de N resultou em aumentos significativos no rendimento de grãos de arroz (de 3217 para 5548 kg ha-1, 2010/11, e de 3392 para 4560 kg ha-1, 2011/12). A taxa de recuperação aparente de nitrogênio diminuiu com o aumento das doses aplicadas de N.