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Fluoride concentrations were determined in saliva from children and young adults by means of a fluoride ion electrode (Orion Research Inc.). Children who consumed drinking water containing 1 ppm fluoride (Group 1) showed a mean fluoride concentration of 0.009 ppm in parotid saliva. Children residing in a community with less than 0.1 ppm fluoride in the drinking water (Group 2) showed a mean concentration of 0.007 ppm. The comparable mean concentration was 0.008 ppm in children from the same community receiving a daily supplement of 1 mg fluoride (Group 3) while adults from a non-fluoridated community who refrained from the use of fluoride dentifrices for one week (Group 4) had a mean concentration of 0.010 ppm in parotid saliva. It was further found that simultaneously collected stimulated parotid and submaxillary saliva had identical concentrations on an individual basis. Fluoride concentrations were higher in whole saliva than in duct saliva from the same individual. The mean fluoride concentration in whole saliva in Group 1 was 0.033 ppm compared to 0.011, 0.015 and 0.017 ppm respectively in Groups 2, 3 and 4. The increased fluoride concentrations in whole saliva were attributed to inclusion of cellular debris and mucus since the concentrations decreased when whole saliva was ‘cleared’ by centrifugation. Also the fluoride concentration tended to decrease in a series of successively collected samples of whole saliva. Dental plaque and material scraped from the tongue contained significant amounts of fluoride.

We review the mechanisms of deleterious nitrogen (N) deposition impacts on temperate forests, with a particular focus on trees and lichens. Elevated anthropogenic N deposition to forests has varied effects on individual organisms depending on characteristics both of the N inputs (form, timing, amount) and of the organisms (ecology, physiology) involved. Improved mechanistic knowledge of these effects can aid in developing robust predictions of how organisms respond to either increases or decreases in N deposition. Rising N levels affect forests in micro‐ and macroscopic ways from physiological responses at the cellular, tissue, and organism levels to influencing individual species and entire communities and ecosystems. A synthesis of these processes forms the basis for the overarching themes of this paper, which focuses on N effects at different levels of biological organization in temperate forests. For lichens, the mechanisms of direct effects of N are relatively well known at cellular, organismal, and community levels, though interactions of N with other stressors merit further research. For trees, effects of N deposition are better understood for N as an acidifying agent than as a nutrient; in both cases, the impacts can reflect direct effects on short time scales and indirect effects mediated through long‐term soil and belowground changes. There are many gaps on fundamental N use and cycling in ecosystems, and we highlight the most critical gaps for understanding potential deleterious effects of N deposition. For lichens, these gaps include both how N affects specific metabolic pathways and how N is metabolized. For trees, these gaps include understanding the direct effects of N deposition onto forest canopies, the sensitivity of different tree species and mycorrhizal symbionts to N, the influence of soil properties, and the reversibility of N and acidification effects on plants and soils. Continued study of how these N response mechanisms interact with one another, and with other dimensions of global change, remains essential for predicting ongoing changes in lichen and tree populations across North American temperate forests.

Introduction Serodiscordant couples are a priority population for delivery of new HIV prevention interventions in Africa. An integrated strategy of delivering time‐limited, oral pre‐exposure prophylaxis (PrEP) to uninfected partners in serodiscordant couples as a bridge to long‐term antiretroviral treatment (ART) for infected partners has been implemented in East Africa, nearly eliminating new infections. We conducted a qualitative evaluation of the integrated strategy in Uganda, to better understand its success. Methods Data collection consisted of 274 in‐depth interviews with 93 participating couples, and 55 observations of clinical encounters between couples and healthcare providers. An inductive content analytic approach aimed at understanding and interpreting couples’ experiences of the integrated strategy was used to examine the data. Analysis sought to characterize: (1) key aspects of services provided; (2) what the services meant to recipients; and (3) how couples managed the integrated strategy. Themes were identified in each domain, and represented as descriptive categories. Categories were grouped inductively into more general propositions based on shared content. Propositions were linked and interpreted to explain “why the integrated strategy worked.” Results Couples found “couples‐focused” services provided through the integrated strategy strengthened partnered relationships threatened by the discovery of serodiscordance. They saw in services hope for “getting help” to stay together, turned joint visits to clinic into opportunities for mutual support, and experienced counselling as bringing them closer together. Couples adopted a “couples orientation” to the integrated strategy, considering the health of partners as they made decisions about initiating ART or accepting PrEP, and devising joint approaches to adherence. A couples orientation to services, grounded in strengthened partnerships, may have translated to greater success in using antiretrovirals to prevent HIV transmission. Conclusions Various strategies for delivering antiretrovirals for HIV prevention are being evaluated. Understanding how and why these strategies work will improve evaluation processes and strengthen implementation platforms. We highlight the role of service organization in shaping couples’ experiences of and responses to ART and PrEP in the context of the integrated strategy. Organizing services to promote positive care experiences will strengthen delivery and contribute to positive outcomes as antiretrovirals for prevention are rolled out.

Mix‐dimensional heterojunctions (MDHJs) photodetectors (PDs) built from bulk and 2D materials are the research focus to develop hetero‐integrated and multifunctional optoelectronic sensor systems. However, it is still an open issue for achieving multiple effects synergistic characteristics to boost sensitivity and enrich the prospect in artificial bionic systems. Herein, electrically tunable Te/WSe2 MDHJs phototransistors are constructed, and an ultralow dark current below 0.1 pA and a large on/off rectification ratio of 106 is achieved. Photoconductive, photovoltaic, and photo‐thermoelectric conversions are simultaneously demonstrated by tuning the gate and bias. By these synergistic effects, responsivity and detectivity respectively reach 13.9 A W−1 and 1.37 × 1012 Jones with 400 times increment. The Te/WSe2 MDHJs PDs can function as artificial bionic visual systems due to the comparable response time to those of the human visual system and the presence of transient positive and negative response signals. This work offers an available strategy for intelligent optoelectronic devices with hetero‐integration and multifunctions. In this work, electrically tunable multiple‐mechanisms synergistic Te/WSe2 MDHJs phototransistors are constructed. By modulating the gate and bias, the R and D* are significantly improved by the synergism of PC, PV, and photo‐thermoelectric (PTE) conversion. Transient PTE photocurrent signals can well simulate the human visual system, implying that the device can undertake the function of artificial bionic visual systems.

The effect of a drug on the intestinal flora and the intestinal barrier is an important evaluation index for drug safety and efficacy. Chemical synthetic drugs are widely used due to their advantages of fast efficacy and low doses, but they are prone to cause drug resistance and inhibit proton pumps, which may harm intestinal health. Traditional Chinese medicine (TCM) has been applied clinically for thousands of years, and how TCMs regulate intestinal health to achieve their effects of disease treatment has become a hot research topic that needs to be resolved. This paper reviews the recent research on the effects of TCMs on intestinal microorganisms and the intestinal mucosal barrier after entering the intestine, discusses the interaction mechanisms between TCMs and intestinal flora, and details the repair effect of TCMs on the intestinal mucosal barrier to provide a reference for the development, utilization, and modernization of TCM.

At present, there is a consensus that the digital economy provides a new impetus for sustainable economic development. Based on domestic and foreign literature reviews, this paper focuses on representative industry sectors; we present China’s 2011–2018 digital economy development index, for 173 cities, from a three-level perspective—internet development, digital literacy, and industrial efficiency improvement. Various models, such as the instrumental variable method, the double difference method, the intermediary effect model, and the spatial econometric model were used to quantitatively analyze the impact of digital economic development on urban economic growth in China. The study finds that: (1) digital economic development in China has a positive effect on urban economic growth, and a heterogeneity of effects exists between different cities. (2) Urban employment is the “effect mechanism” of digital economic growth on urban economic growth. (3) The direct effect of digital economic development on urban economic growth in China is positive, the spillover effect is positive, the direct effect is greater than the spillover effect, and the total effect is positive. The research results enrich the measurement methods used in urban digital economic development in China, providing new perspectives for studying the influence mechanisms of digital economic development on urban economic growth.

As an important type of soil erosion, freeze-thaw erosion occurs primarily at high latitude and altitude. The overview on the effect of freeze-thaw on soil erosion was provided. Soil erosion was affected by freeze-thaw processes, as thawing and water erosion reinforce each other. Remote sensing provided an unprecedented approach for characterizing the timing, magnitude, and patterns of large-scale freeze-thaw and soil erosion changes. Furthermore, the essence of soil freeze-thaw was the freeze and thaw of soil moisture in the pores of soil. Freeze-thaw action mainly increased soil erodibility and made it more vulnerable to erosion by destroying soil structure, changing soil water content, bulk density, shear strength and aggregate stability, etc. However, the type and magnitude of changes of soil properties have been related to soil texture, water content, experimental conditions and the degree of exposure to freeze-thaw. The use of indoor and field experiments to further reveal the effect of freeze-thaw on soil erosion would facilitate improved forecasting, as well as prevention of soil erosion during thawing in regions with freeze-thaw cycles.

Bee venom (BV), a type of defensive venom, has been confirmed to have favorable activities, such as anti-tumor, neuroprotective, anti-inflammatory, analgesic, anti-infectivity effects, etc. This study reviewed the recent progress on the pharmacological effects and mechanisms of BV and its main components against cancer, neurological disorders, inflammatory diseases, pain, microbial diseases, liver, kidney, lung and muscle injury, and other diseases in literature during the years 2018–2021. The related target proteins of BV and its main components against the diseases include Akt, mTOR, JNK, Wnt-5α, HIF-1α, NF-κB, JAK2, Nrf2, BDNF, Smad2/3, AMPK, and so on, which are referring to PI3K/Akt/mTOR, MAPK, Wnt/β-catenin, HIF-1α, NF-κB, JAK/STAT, Nrf2/HO-1, TrkB/CREB/BDNF, TGF-β/Smad2/3, and AMPK signaling pathways, etc. Further, with the reported targets, the potential effects and mechanisms on diseases were bioinformatically predicted via Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, disease ontology semantic and enrichment (DOSE) and protein-protein interaction (PPI) analyses. This review provides new insights into the therapeutic effects and mechanisms of BV and its main components on diseases.