Room‐temperature phosphorescence (RTP) materials with high efficiency have attracted much attention because they have unique characteristics that cannot be realized in conventional fluorescent ...materials. Unfortunately, efficient RTP in metal‐free organic materials is very rare and it has traditionally been considered as the feature to divide purely organic compounds from organometallic and inorganic compounds. There has been increasing research interest in the design and preparation of metal‐free organic RTP materials in recent years. It has been reported that intermolecular interactions make a big difference to the photophysical behavior of organic molecules. In this regard, herein, the parameters that affect RTP efficiency are discussed, and a brief review of recent intermolecular halogen‐/hydrogen‐bonding strategies for efficient RTP in metal‐free organic materials are provided. The opportunities and challenges are finally elaborated in the hope of guiding promising directions for the design and application of RTP materials.
Fixed formations: Room‐temperature phosphorescence (RTP) materials have attracted increasing research interest because of their promising functional applications. Recent examples of intermolecular halogen‐/hydrogen‐bonding strategies for efficient RTP in metal‐free organic materials are summarized.
Rayleigh’s criterion for resolving two incoherent point sources has been the most influential measure of optical imaging resolution for over a century. In the context of statistical image processing, ...violation of the criterion is especially detrimental to the estimation of the separation between the sources, and modern far-field superresolution techniques rely on suppressing the emission of close sources to enhance the localization precision. Using quantum optics, quantum metrology, and statistical analysis, here we show that, even if two close incoherent sources emit simultaneously, measurements with linear optics and photon counting can estimate their separation from the far field almost as precisely as conventional methods do for isolated sources, rendering Rayleigh’s criterion irrelevant to the problem. Our results demonstrate that superresolution can be achieved not only for fluorophores but also for stars.
Recycling processes (such as carbon, oxygen, nitrogen cycles etc.) occur each day as an essential character for nature. Managed ecosystems have maintained the natural environment in a state of great ...harmony for millions of years. In recent decades, various polymers with long‐term durability have been developed to be the most predominantly used materials, and have drastically changed the lifestyle of human beings. However, the tremendous growth of plastic debris, with no or very low degradability, over the past decades significantly affects the natural environment. The use of alternative recycling materials is the best option from the environmental point of view. This critical review highlights the most significant progress in chemically recyclable materials, especially several typical systems, which embody perfect recycling between polymers and the starting monomers.
Recycling processes, such as carbon cycles, occur every day as an essential character for nature. Harmony in nature inspires chemists’ motivation to design monomer/polymer cycles by reversible polymerization/depolymerization processes. This review illustrates the most significant progress in chemically recyclable materials, which embody perfect recycling between polymers and the starting monomers.
Chemical recycling of polymers to their constituent monomers is the foremost challenge in building a sustainable circular plastics economy. Here, we report a strategy for highly efficient ...depolymerization of various CO2‐based alicyclic polycarbonates to epoxide monomers in solvent‐free conditions by a simple CrIII‐Salen complex mediated catalytic pyrolysis process. The chemical recycling of the widely studied poly(cyclohexene carbonate) exhibits excellent reactivity (TOF up to 3000 h−1, 0.1 mol % catalyst loading) and high epoxide monomer selectivity (>99 %). Mechanistic investigation reveals that the process proceeds in a sequential fashion via a trans‐carbonate intermediate.
The catalytic pyrolysis of various CO2‐based polycarbonates in bulk recovers epoxide monomers quantitatively using a simple CrIII‐Salen catalyst. It even proceeds very efficiently for chemical recycling of poly(cyclohexene carbonate) from a plastic waste mixture and thus provides a closed‐loop approach towards a circular plastic economy in applications of CO2‐based polycarbonates.
Plastics are indispensable materials in modern society; however, their extensive use has contributed to the depletion of finite natural resources and caused severe environmental issues. One ...end‐of‐use solution for plastics involves the chemical recycling of polymers back to monomers for repolymerization to virgin polymers without changing the material properties, allowing the establishment of a circular material economy. This concept focuses on the critical advantages of chemically recyclable polymers in terms of monomer design, material properties, and the feasibility of bulk depolymerization. The recyclability via bulk thermolysis of various polyesters, CO2‐based polycarbonates, and polyacetals produced via ring‐opening polymerization is highlighted through discussions regarding rational monomer design and efficient catalyst development. An outlook and perspective are provided to delineate the future challenges in the rational design of monomer and polymer structures that deliver the desired materials performance while being suitable for bulk thermolysis with high (de)polymerization activity and selectivity.
The chemical recycling of polymers back to monomers for repolymerization to virgin polymers offers a solution for the end‐of‐use problems of plastics and the potential to establish a circular material economy. This concept focuses on the critical advantages of chemically recyclable polymers in terms of monomer design, material properties, and the feasibility of bulk depolymerization.
Critical patients with the coronavirus disease 2019 (COVID-19), even those whose nucleic acid test results had turned negative and those receiving maximal medical support, have been noted to progress ...to irreversible fatal respiratory failure. Lung transplantation (LT) as the sole therapy for end-stage pulmonary fibrosis related to acute respiratory distress syndrome has been considered as the ultimate rescue therapy for these patients.
From February 10 to March 10, 2020, three male patients were urgently assessed and listed for transplantation. After conducting a full ethical review and after obtaining assent from the family of the patients, we performed three LT procedures for COVID-19 patients with illness durations of more than one month and extremely high sequential organ failure assessment scores.
Two of the three recipients survived post-LT and started participating in a rehabilitation program. Pearls of the LT team collaboration and perioperative logistics were summarized and continually improved. The pathological results of the explanted lungs were concordant with the critical clinical manifestation, and provided insight towards better understanding of the disease. Government health affair systems, virology detection tools, and modern communication technology all play key roles towards the survival of the patients and their rehabilitation.
LT can be performed in end-stage patients with respiratory failure due to COVID-19-related pulmonary fibrosis. If confirmed positive-turned-negative virology status without organ dysfunction that could contraindicate LT, LT provided the final option for these patients to avoid certain death, with proper protection of transplant surgeons and medical staffs. By ensuring instant seamless care for both patients and medical teams, the goal of reducing the mortality rate and salvaging the lives of patients with COVID-19 can be attained.
Quantum Fisher information matrix (QFIM) is a core concept in theoretical quantum metrology due to the significant importance of quantum Cramér-Rao bound in quantum parameter estimation. However, ...studies in recent years have revealed wide connections between QFIM and other aspects of quantum mechanics, including quantum thermodynamics, quantum phase transition, entanglement witness, quantum speed limit and non-Markovianity. These connections indicate that QFIM is more than a concept in quantum metrology, but rather a fundamental quantity in quantum mechanics. In this paper, we summarize the properties and existing calculation techniques of QFIM for various cases, and review the development of QFIM in some aspects of quantum mechanics apart from quantum metrology. On the other hand, as the main application of QFIM, the second part of this paper reviews the quantum multiparameter Cramér-Rao bound, its attainability condition and the associated optimal measurements. Moreover, recent developments in a few typical scenarios of quantum multiparameter estimation and the quantum advantages are also thoroughly discussed in this part.
Abstract
Background
The prevalence of neural tube defects (NTDs) in China declined during 2000–2017 with periconceptional folic acid (FA) supplementation, which is effective in reducing the risk of ...birth defects. We aimed to assess the knowledge and actual use of FA among Chinese pregnant women and to explore factors associated with FA use before pregnancy.
Methods
All data were collected in face-to-face interviews during health visits among pregnant women. We collected information about knowledge and use of FA supplements and demographic, socioeconomic, and health status. One maternity and childcare hospital was chosen in each of four cities: Beijing, Huaibei, Kunming, and Haikou. In total, 435 pregnant women were randomly recruited for interviews conducted from June to December 2016.
Results
A total of 428 pregnant women were included in this survey. Of these, 82.0% (351/428) knew that FA can prevent NTDs, and 75.9% (325/428) knew the correct time to take FA. Overall, 65.9% (282/428) of women knew both that FA can prevent NTDs and the recommended time to take FA before pregnancy. Approximately 95.1% (407/428) of women reported having ever taken FA, only 46.3% (198/428) had begun to take FA supplementation before conception, and 64.5% (109/169) of women from rural areas failed to take FA before pregnancy. Women living in northern China (odds ratio OR = 1.81, 95% confidence interval CI, 1.18–2.77), those with unplanned pregnancy (OR = 1.99, 95% CI 1.30–3.04), and highly educated women (OR = 2.37, 95% CI 1.45–3.88) were more likely to know about FA. Women who were homemakers (OR = 1.94, 95% CI 1.21–3.11) and had unplanned pregnancy (OR = 6.18, 95% CI 4.01–9.53) were less likely to begin taking FA before pregnancy.
Conclusions
Our survey showed that most pregnant women knew about FA. Although preconception intake of FA can help to reduce NTDs, improving the rate of FA intake before pregnancy is needed in urban areas of China, especially among homemakers and women from rural areas or with unplanned pregnancy. Campaigns are needed to increase awareness about FA and FA use before pregnancy among rural women, homemakers, and those with unplanned pregnancy and lower education levels.
The quantum multiparameter estimation is very different from the classical multiparameter estimation due to Heisenberg's uncertainty principle in quantum mechanics. When the optimal measurements for ...different parameters are incompatible, they cannot be jointly performed. We find a correspondence relationship between the inaccuracy of a measurement for estimating the unknown parameter with the measurement error in the context of measurement uncertainty relations. Taking this correspondence relationship as a bridge, we incorporate Heisenberg's uncertainty principle into quantum multiparameter estimation by giving a trade-off relation between the measurement inaccuracies for estimating different parameters. For pure quantum states, this trade-off relation is tight, so it can reveal the true quantum limits on individual estimation errors in such cases. We apply our approach to derive the trade-off between attainable errors of estimating the real and imaginary parts of a complex signal encoded in coherent states and obtain the joint measurements attaining the trade-off relation. We also show that our approach can be readily used to derive the trade-off between the errors of jointly estimating the phase shift and phase diffusion without explicitly parametrizing quantum measurements.
Background and aims
The outbreak of coronavirus disease 2019 (COVID‐19) caused by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection has recently spread worldwide and been ...declared a pandemic. We aim to describe here the various clinical presentations of this disease by examining eleven cases.
Methods
Electronic medical records of 11 patients with COVID‐19 were collected, and demographics, clinical manifestations, outcomes, key laboratory results, and radiological images are discussed.
Results
The clinical course of the eleven cases demonstrated the complexity of the COVID‐19 profile with different clinical presentations. Clinical manifestations range from asymptomatic cases to patients with mild and severe symptoms, with or without pneumonia. Laboratory detection of the viral nucleic acid can yield false‐negative results, and serological testing of virus‐specific IgG and IgM antibodies should be used as an alternative for diagnosis. Patients with common allergic diseases did not develop distinct symptoms and severe courses. Cases with a pre‐existing condition of chronic obstructive pulmonary disease or complicated with a secondary bacterial pneumonia were more severe.
Conclusion
All different clinical characteristics of COVID‐19 should be taken into consideration to identify patients that need to be in strict quarantine for the efficient containment of the pandemic.
Clinical manifestations of COVID‐19 range from asymptomatic cases to patients with mild and severe symptoms, with or without pneumonia. Laboratory detection of the viral nucleic acid can yield false‐negative results, and serological testing of virus‐specific IgG and IgM antibodies should be used as an alternative for diagnosis. Patients with common allergic diseases did not develop distinct symptoms and severe courses. Cases with a pre‐existing condition of chronic obstructive pulmonary disease or complicated with a secondary bacterial pneumonia were more severe.
PDF
