BACKGROUND: Tight-fitting masks and respirators, in manikin studies, improved aerosol source control compared to loose-fitting masks. Whether this translates to humans is not known.
METHODS: We compared efficacy of masks (cloth and surgical) and respirators (KN95 and N95) as source control for SARS-CoV-2 viral load in exhaled breath of volunteers with COVID-19 using a controlled human experimental study. Volunteers (N = 44, 43% female) provided paired unmasked and masked breath samples allowing computation of source-control factors.
RESULTS: All masks and respirators significantly reduced exhaled viral load, without fit tests or training. A duckbill N95 reduced exhaled viral load by 98% (95% CI: 97%-99%), and significantly outperformed a KN95 (p < 0.001) as well as cloth and surgical masks. Cloth masks outperformed a surgical mask (p = 0.027) and the tested KN95 (p = 0.014).
CONCLUSIONS: These results suggest that N95 respirators could be the standard of care in nursing homes and healthcare settings when respiratory viral infections are prevalent in the community and healthcare-associated transmission risk is elevated.
BACKGROUND: Defense Advanced Research Projects Agency, National Institute of Allergy and Infectious Diseases, Centers for Disease Control and Prevention, the Bill & Melinda Gates Foundation, and The Flu Lab.

Over the last four decades, the Chinese government has predominantly employed emission fees as a regulatory strategy to mitigate pollution from firms. However, the effectiveness of escalating emission fee rates on the emission levels of Chinese firms has not been examined. This study utilizes data from more than 80,000 Chinese firms spanning 2004-2013, employing difference-in-differences models to assess the effects of rising emission fee rates on firm emissions. The findings indicate the following: (1) Increased emission fee rates substantially reduce sulfur dioxide and chemical oxygen demand emissions among Chinese firms; (2) These heightened fees encourage firms to implement both end-of-pipe treatment and source control for sulfur dioxide and end-of-pipe treatment for chemical oxygen demand; (3) The emission reduction effects vary according to firm ownership and size. This research offers empirical evidence on the efficacy of emission fee systems and provides valuable insights for developing market incentive-based environmental regulations in the future.

The spatial diffusion mechanism underlying cropland heavy metal contamination in a complex peri-urban environment provides a crucial basis for controlling soil contamination from the source and also for ensuring the quality of black soil croplands. However, previous studies have struggled to locate the contamination sources or trace their diffusion trajectories in space. In this regard, representative peri-urban croplands in the black soil region were selected as a case, and soil As, Pb, Hg, and Cd were deemed as the main research objects. Moreover, an affinity propagation algorithm and spatial autocorrelation regression were adopted to measure the contamination patterns and identify the major determinants, in an attempt to reveal how heavy metals are diffused in the peri-urban cultivated area. The results indicated that ① the average concentrations of soil As and Cd were 39.35 mg·kg-1 and 0.183 mg·kg-1, respectively, which exhibited heavier accumulation in the study area. The Nemerow index indicated that there were 52.38% of croplands indicating slight contamination. ② The affinity propagation algorithm identified three potential sources with a similar impact extent for As, which were situated in the typical cultivated area. Both of the two identified potential sources for Pb were situated in close proximity to Fanjiatun Town. The diffusion patterns for Hg and Cd were complex, particularly for the latter, of which the potential sources were scattered in multiple places. ③ The spatial lag model indicated that the distributions of As and Cd were mainly controlled by the intensive agriculture in peri-urban areas, among which As was related to the application of herbicide and Cd was related to the distribution of protected agriculture. Pb was mainly influenced by urbanization and industrialization, whereas Hg was found to be associated with the migration conditions of the soil. However, the regulating function provided by either croplands or their nearby environment did not play an important role in determining the diffusion patterns of heavy metals. The present study enriches the theory and methods for the spatial analysis of cropland heavy metal contamination and is significant for controlling contamination from the source in peri-urban croplands in the black soil region.

Intra-abdominal infections (IAI) are among the most common global healthcare challenges and they are usually precipitated by disruption to the gastrointestinal (GI) tract. Their successful management typically requires intensive resource utilization, and despite the best therapies, morbidity and mortality remain high. One of the main issues required to appropriately treat IAI that differs from the other etiologies of sepsis is the frequent requirement to provide physical source control. Fortunately, dramatic advances have been made in this aspect of treatment. Historically, source control was left to surgeons only. With new technologies non-surgical less invasive interventional procedures have been introduced. Alternatively, in addition to formal surgery open abdomen techniques have long been proposed as aiding source control in severe intra-abdominal sepsis. It is ironic that while a lack or even delay regarding source control clearly associates with death, it is a concept that remains poorly described. For example, no conclusive definition of source control technique or even adequacy has been universally accepted. Practically, source control involves a complex definition encompassing several factors including the causative event, source of infection bacteria, local bacterial flora, patient condition, and his/her eventual comorbidities. With greater understanding of the systemic pathobiology of sepsis and the profound implications of the human microbiome, adequate source control is no longer only a surgical issue but one that requires a multidisciplinary, multimodality approach. Thus, while any breach in the GI tract must be controlled, source control should also attempt to control the generation and propagation of the systemic biomediators and dysbiotic influences on the microbiome that perpetuate multi-system organ failure and death. Given these increased complexities, the present paper represents the current opinions and recommendations for future research of the World Society of Emergency Surgery, of the Global Alliance for Infections in Surgery of Surgical Infection Society Europe and Surgical Infection Society America regarding the concepts and operational adequacy of source control in intra-abdominal infections.

Tailing sand contains a large number of heavy metals and sulfides that are prone to forming acid mine drainage (AMD), which pollutes the surrounding surface environment and groundwater resources and damages the ecological environment. Microbially induced calcium carbonate precipitation (MICP) technology can biocement heavy metals and sulfides in tailing sand and prevent pollution via source control. In this study, through an unconfined compressive strength test, permeability test, and toxic leaching test (TCLP), the curing effect of MICP was investigated in the laboratory and the effect of grouting rounds on curing was also analyzed. In addition, the curing mechanism of MICP was studied by means of Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction spectroscopy (XRD), and scanning electron microscopy (SEM). The experimental results showed that MICP could induce calcium carbonate precipitation through relatively complex biochemical and physicochemical reactions to achieve the immobilization of heavy metals and sulfides and significantly reduce the impact of tailing sand on the surrounding environment.

In order to control the spread of Covid-19, authorities provide various prevention guidelines and recommendations for health workers and the public. Personal protection equipment (PPE) and physical barrier are the most widely applied prevention measures in practice due to their affordability and ease of implementation. This study aims to investigate the effect of PPE and physical barriers on mitigating the short-range airborne transmission between two people in a ventilated environment. Four types of PPE (surgical mask, two types of face shield, and mouth visor), and two different sizes of the physical barrier were tested in a controlled environment with two life-size breathing thermal manikins. The PPE was worn by the source manikin to test the efficiency of source control. The measurement results revealed that the principles of PPE on preventing short-range droplet and airborne transmission are different. Instead of filtering the fine droplet nuclei, they mainly redirect the virus-laden exhalation jet and avoid the exhaled flow entering the target\'s inhalation region. Physical barriers can block the spreading of droplet nuclei and create a good micro environment at short distances between persons. However, special attention should be paid to arranging the physical barrier and operating the ventilation system to avoid the stagnant zone where the contaminant accumulates.

The annually recurring Yellow Sea green tide causes significant economic, social, and ecological impacts in China. Currently, the magnitude of Yellow Sea green tide is usually evaluated according to the snap shot maximum algal coverage area or artificially removed algal biomass. However, this method ignores growth of the alga Ulva prolifera and thus needs improvement. We build a model to predict algal growth in drifting from upstream and the potential muaximum biomass of green tide. The results suggest that the potential maximum biomass is significantly higher than those estimated merely from maximum algal coverage area, particularly for years with extended period of algal loading in the upstream. Our method improves the evaluation of the magnitude of green tide and provides a scientific basis for developing effective countermeasures to reduce the persistent disaster.

The Chinese guidelines for IAI presented here were developed by a panel that included experts from the fields of surgery, critical care, microbiology, infection control, pharmacology, and evidence-based medicine. All questions were structured in population, intervention, comparison, and outcomes format, and evidence profiles were generated. Recommendations were generated following the principles of the Grading of Recommendations Assessment, Development, and Evaluation system or Best Practice Statement (BPS), when applicable. The final guidelines include 45 graded recommendations and 17 BPSs, including the classification of disease severity, diagnosis, source control, antimicrobial therapy, microbiologic evaluation, nutritional therapy, other supportive therapies, diagnosis and management of specific IAIs, and recognition and management of source control failure. Recommendations on fluid resuscitation and organ support therapy could not be formulated and thus were not included. Accordingly, additional high-quality clinical studies should be performed in the future to address the clinicians\' concerns.

Most abdominal infections are mixed infections caused by aerobic and anaerobic bacteria. Anaerobic infections are characterized by rancid secretions or abscess formation. Early implementation of source control is the key in the treatment of abdominal anaerobic infections. Damage control should be followed as one of the principles of surgical treatment. As the in vitro isolation and culture of anaerobic bacteria as well as its drug sensitivity test are time-consuming and sometimes inaccurate, the treatment of anaerobic bacteria infection is mostly empirical. Anti-infective therapy should be employed once anaerobic bacteria infection is confirmed. Ertapenem, Mosifloxacin, and Cefoperazone-sulbactam can be used for first-line monotherapy, while combination therapy can use second- or third-generation Cephalosporin, Quinolones plus Nitroimidazoles. Nutritional support and anti-shock treatment should not be neglected when implementing surgical control of infection source and antimicrobial therapy. Considering the increasing drug resistance of anaerobic bacteria, and the higher drug resistance rate in China as compared to western countries, the choice of antibiotics should be made rationally and based on epidemiological characteristics of anaerobic bacteria in different regions.
大多数腹腔感染是由需氧菌和厌氧菌引起的混合感染，厌氧菌感染以产生腐臭味的分泌物或形成脓肿为特点。尽早实行感染源控制是治疗腹腔厌氧菌感染的关键环节，应优先采用对生理损伤小的有效干预措施。对于行手术治疗的患者，需遵循损伤控制原则。由于厌氧菌的体外分离培养和药敏试验耗时长且结果不准确，厌氧菌感染的治疗多为经验性，当明确厌氧菌感染后，应尽早行抗感染治疗，厄他培南、莫西沙星、头孢哌酮舒巴坦可作为一线的单药治疗；联合用药可选择二、三代头孢菌素、喹诺酮类加硝基咪唑类抗厌氧菌药物。在外科手术行感染源的控制和抗生素治疗的同时，营养支持和抗休克的治疗不容忽视。近年来，厌氧菌耐药性明显增加，我国的耐药率要明显高于西方国家，需结合不同地区的厌氧菌流行病学特点，合理选择抗厌氧菌药物。.

In recent years, both international and domestic societies have published several guidelines on diagnosis and management of intra-abdominal infection. Due to the different evidence and the different methods adopted in the actual formulation of the guidelines, the recommendations of each version of the guidelines are different. Three international guidelines with great impacts were reviewed, including Diagnosis and management of complicated intra-abdominal infection: guidelines by the Surgical Infection Society and the Infectious Diseases Society of America published in 2010, The Surgical Infection Society revised guidelines on the management of intra-abdominal infection published in 2017, and The management of intra-abdominal infections from a global perspective by the World Society of Emergent Surgery. The above guidelines were used to compare with the Chinese guidelines on the diagnosis and management of intra-abdominal infection (2019) which was published in early 2020. Recommendations on the disease severity classification, source control, and antimicrobial therapy are further explained in order to provide guidelines for clinicians.
近年来，国内外学会先后发布了若干版本的腹腔感染诊治指南。由于各版指南依据的循证医学证据不同，指南实际制定采取的方法亦不同，造成了各版指南中推荐意见的差异。本文仅选取2010年由美国感染病学会（IDSA）与北美外科感染学会（SIS）联合发布的《复杂腹腔感染诊治指南》、由SIS牵头更新形成的2017版《腹腔感染诊治指南》和2017年由世界急诊外科学会发布的《基于全球视野的IAI诊治指南》这三部国际影响力较大的指南，以及2020年初我国发表的首部《中国腹腔感染诊治指南（2019版）》，旨在就各版指南在疾病严重度分级、感染源控制以及抗感染治疗等方面的推荐意见进行解读，希望能够为临床上更好地应用指南提供参考。.