Low Recovery Rate Research Articles

A new strategy of loading ferritin with “iron-Dox” complex

<p indent=0mm>Ferritin, owing to its unique nanocage architecture, self-assembling ability, inherent tumor-targeting, excellent biocompatibility and capability to be produced on a large scale, has emerged as a promising nano-drug carrier for clinical translation. Currently, loading of anti-tumor drug, especially doxorubicin (Dox), in ferritin has been widely investigated via either passive encapsulation or active internalization. Among these methods, strategies that pre-complex metal ions with Dox to form “metal-Dox” complexes that promote entry of Dox into the cavity of ferritin actively enable higher loading capacity and enhanced killing effect. However, these ways currently used still suffer from low recovery rate and impaired integrity. In order to overcome these shortcomings, we here report a new loading strategy, a temperature-related and iron ion-depended method, in which we utilized human heavy chain ferritin (human HFn) and successfully constructed the HFn(Fe-Dox) drug delivery system (HFeD), which achieved a high loading capacity (80–100 Dox per HFn), high encapsulation rate (50%–63%) and considerable recovery rate of HFn (80%–90%). Meanwhile, the strategy reported here preserves the structural integrity, tumor-targeting and controlled drug release of HFn, and thus HFeD is able to specifically target and kill tumor cells, which will inform the druggability of HFeD and application of ferritin-based nano-drug carriers.

One-step preparation of carbonaceous spheres rich in phosphate groups via hydrothermal carbonization for effective phosphopeptides enrichment

A green strategy was developed to prepare carbonaceous spheres rich in phosphoric acid groups on the surface with D-Glucose 6-phosphate sodium salt (called G6PNa2) as a sole carbon source through one-step hydrothermal carbonization method. The method is simple and facile and meets the standards of green chemistry as water is the sole solvent employed. Following the hydrothermal carbonization synthesis, the carbonaceous spheres were further functionalized with Ti4+. The main factors including reaction temperature, reaction time, and concentration of G6PNa2 were systematically studied in order to obtain the desirable morphology and the optimum phosphopeptides enrichment, for the resulting Ti4+ functionalized carbonaceous spheres (CS-Ti4+). The performance evaluation of the CS-Ti4+ prepared under the optimum conditions demonstrated excellent selectivity (1:1000), low detection limit (1 fmol) and high recovery rate (85%) towards phosphopeptides. Furthermore, 24 low-abundance phosphopeptides were captured from human saliva using CS-Ti4+, indicating its great potential in mass spectrometry-based phosphoproteome studies.

Evaluation of Performance of Existing RO Drinking Water Stations in the North Central Province, Sri Lanka.

Reverse osmosis (RO) drinking water stations have been introduced to provide safe drinking water for areas with prevailing chronic kidney disease with unknown (CKDu) etiology in the dry zone of Sri Lanka. In this investigation, RO drinking water stations established by community-based organizations (CBO) in the North Central Province (NCP) were examined. Water samples were collected from source, permeate, and concentrate in each station to determine water quality and performance. Furthermore, the operators of the systems were interviewed to evaluate operational and maintenance practices to identify major issues related to the RO systems. Results show that the majority (>93%) of RO systems had higher salt rejection rates (>92%), while water recovery varied from 19.4% to 64%. The removal efficiencies of hardness and alkalinity were averaged at 95.8% and 86.6%, respectively. Most dominant ions such as Ca2+, Mg2+, K+, Na+, Ba2+, Sr2+ Cl−, F−, and SO42− showed higher rejections at averaged values of 93.5%, 97.4%, 86.6%, 90.8%, 95.4%, 96.3%, 95.7%, 96.6%, and 99.0%, respectively. Low recovery rates, lower fluoride levels in product water, and membrane fouling were the main challenges. Lack of knowledge and training were the major issues that could shorten the lifespan of RO systems.

A Systematic Review of Construction and Demolition Waste Management in Australia: Current Practices and Challenges

Construction and demolition waste (C&amp;DW) has a deleterious impacts on sustainability not only in developing countries but also in developed nations. For example, Australia generated more than 27 million tonnes of C&amp;DW in 2018–2019; however, only 60% of this waste stream was recovered. Considering this low recovery rate, lower than many developed nations, and with regards to the increasing rate of C&amp;DW generation, extra attention should be given to the construction and demolition waste management (C&amp;DWM) in Australia. Therefore, this research attempts to accurately understand the current practices and challenges of C&amp;DWM in Australia. To do so, primarily, a systematic review of studies relevant to C&amp;DWM from 2010 to 2021 was performed. In this step, 26 research documents were meticulously analysed to identify the current practices of C&amp;DWM in Australia. Then, an in-depth interview with three experts were undertaken to verify the major results and to investigate the challenges of C&amp;DWM in Australia. The results indicated that three factors significantly affect C&amp;DWM in Australia, namely attitudes and behaviour of C&amp;DWM stakeholders, C&amp;DWM in project life cycles, and C&amp;DWM regulations with regards to sustainability, adding that the latter was revealed as the most effective in C&amp;DWM in Australia.

Response Options for an Offshore Deepwater Blow-Out, A Generic Evaluation of Individual and Combined Response Strategies

Abstract The low oil recovery rates reported during Macondo (3–5% of the released oil) have caused discussions regarding the efficiency of mechanical recovery compared to other oil spill response options. These low recovery rates have unfortunately been used as reference recovery rates in several later modelling studies and oil spill response analysis. Multiple factors could explain these low rates, such as operational priorities, where dispersants and/or in situ burning are given priority before mechanical recovery; extended safety zones; availability of adequate equipment and storage capacity of collected oil; the number of units available; the level of training and the available remote sensing support to guide operations. This study uses the OSCAR oil spill model to simulate a deep-water oil release to evaluate the effect of different response options both separately and in combination. The evaluated response options are subsea dispersant injection, mechanical recovery, and a combination of these. As expected, Subsea Dispersant Injection (SSDI) was highly effective and resulted in a significant reduction in residual surface oil (8% of released oil volume, versus 28% for the non-response option, NR). However, using large offshore oil recovery systems also reduced residual surface oil with a similar amount (9% of released oil volume). These results deviate significantly from the efficiency numbers reported after the Macondo incident and from later modelling studies scaled after the Macondo recovery rates. The increased efficiency of mechanical reported in this study is mainly due to inclusion of updated descriptions of response capabilities, reduced exclusion zone, a more realistic representation of surface oil distribution and modelling of response units' interactions with oil, (efficient oil recovery only on thick parts of the oil slick). The response capabilities and efficiency numbers for the different response options used in this study are based on equipment specifications from multiple response providers and authorities (Norwegian Clean Seas organisation (NOFO), Oil Spill Response (OSRL), Norwegian Coastal Administration (NCA), US Bureau of Safety and Environmental Enforcement (BSEE) and others). These capabilities are justified by well-established contingency plans, offshore exercises and annual equipment performance testing with oil.

Potential antimicrobial properties of the Ulva lactuca extract against methicillin-resistant Staphylococcus aureus-infected wounds: A review.

Methicillin-resistant Staphylococcus aureus (MRSA), currently a major problem in hospitals worldwide, is one of the most common causes of nosocomial disease through surgical wound infection. MRSA-infected wounds have very low recovery rates and have become more problematic as some antibiotics are not effective against MRSA. Several antimicrobial and anti-inflammatory agents of green algae (Ulva lactuca) in the form of alkaloids, triterpenoids, steroids, saponins, and flavonoids have the potential to accelerate the wound healing process following MRSA wound infection. Various active compounds contained in the U. lactuca extract are thought to have multiple antibacterial and anti-inflammatory properties that can overcome the MRSA antimicrobial resistance and accelerate tissue growth in the wound healing process. This review aims to describe the potential of Ulva lactuca extract against MRSA-infected wound healing.

Beneficial Potential of Banha-Sasim-Tang for Stress-Sensitive Functional Dyspepsia via Modulation of Ghrelin: A Randomized Controlled Trial.

Background: Functional dyspepsia (FD) is a highly complex pathophysiologic disease, which shows low recovery and high relapse rates. Therefore, a growing number of clinicians and patients are looking for alternative herbal medicine. Banha-Sasim-Tang (BST) is an herbal prescription for treating a wide range of dyspepsia in traditional Korean medicine (TKM). Aim of the study: This study aimed to evaluate the efficacy of BST on FD in patients with psychological stress-related symptoms and to investigate the involvement of ghrelin. This study is registered at https://cris.nih.go.kr/with the identification number KCT 0002811. Materials and methods: A total of 31 participants with FD who met the Rome IV criteria and the psychological stress-related pattern were enrolled in a double-blind, randomized, and controlled study. Participants were randomly assigned to the BST group (10 g twice daily for 4 weeks) or placebo group. The primary endpoint was a change in the Nepean Dyspepsia Index–Korean (NDI-K) score. The secondary endpoints were changes in the Visual Analog Scale (VAS) scores and plasma ghrelin level. Results: All participants completed the study (n = 15 for BST, n = 16 for placebo). BST decreased NDI-K scores compared with placebo, but the difference was not statistically significant (37.40 ± 27.40 vs 22.50 ± 23.85, p = 0.12). VAS scores and plasma total ghrelin levels were significantly improved in patients who were treated with BST (3.19 ± 1.60 vs 1.38 ± 2.85, p = 0.03 for VAS and 105.69 ± 287.89 vs -142.31 ± 314.32, p = 0.03 for total ghrelin). No BST-related adverse effects were observed during the trial. Conclusion: Our results indicate the clinical potential of BST for FD patients and are the first study to show the modulation of plasma ghrelin as one of its corresponding mechanisms. Clinical Trial Registration: https://cris.nih.go.kr/, identifier KCT 0002811.

In vitro evaluation of physicochemical variables on the nematophagous fungus Duddingtonia flagrans.

Duddingtonia flagrans is a biological alternative to the use of anthelmintic drugs in ruminants. This fungus must be ingested by the animal, pass through the cavities of the digestive tract and reach the feces where it develops traps that capture the nematodes. The severe conditions encountered in this process negatively affect the fungus, which is reflected in the low recovery rates compared to the amount administered. The aim of this study was to evaluate independently the in vitro effect of typical physical and chemical conditions of the gastrointestinal cavities of ruminants on the concentration, viability, and the in vitro nematode predatory ability of the chlamydospores of D. flagrans. The factors evaluated individually were pH (2, 6, and 8), temperature (28 ± 2°C and 39 ± 2°C), exposure to artificial saliva, and milling. The results showed that the concentration and viability of D. flagrans were not affected by the action of pH, temperature, milling, or exposure to artificial saliva. Regarding the in vitro nematode predatory ability, a reduction was observed after the milling process and the exposure for 24 h at different pH.

Breeding dispersal movements of Dupont’s Lark Chersophilus duponti in fragmented landscape

SummaryUnderstanding patterns of dispersal behaviour of threatened species is important in conservation biology and population ecology, especially in fragmented landscapes. Dupont’s Lark Chersophilusduponti is a threatened passerine whose European population has declined by around 40% in the last decade. To study natal and breeding dispersal of the species, we used a long-term mark-recapture dataset (2011–2019) and analysed the records of 32 males (39 dispersal movements) and five females (five dispersal movements) captured during the breeding season at Rincón de Ademuz (Valencia, eastern Spain). Adult birds had a median breeding dispersal of 154 m (Q25-Q75 = 70.0–300.3). Among these captures, two adult males dispersed to a new patch of habitat separated by more than 5,800 m. Only one out of 26 nestlings ringed was trapped as an adult bird, which occurred at a site different from the natal territory (4,500 m). Our results show a low breeding dispersal for the species and are, in essence, in agreement with previous studies carried out in the Ebro Valley metapopulation, one of the core areas for the species in Europe. Nonetheless, unlike in the Ebro Valley, we detected movements of adult birds between habitat patches. The low recovery rate of young birds suggests that they left their natal sites and moved outside the study area or that their survival rate was very low. Future studies focused on the post-fledging survival rate and natal dispersal movements are essential to determine effective conservation measures for the species. Habitat management actions in occupied and potential sites should be carried out close to the areas inhabited by the species to increase the success rate of the interventions and the effective dispersal and therefore population connectivity.

Cognitive therapy compared with CBT for social anxiety disorder in adolescents: a feasibility study.

Social anxiety disorder (SAD) is common, typically starts in adolescence and has a low natural recovery rate. Existing psychological treatments for adolescent SAD are only moderately effective. It is possible that recovery rates for adolescents could be substantially improved by adapting a psychological therapy that is highly effective among adults with SAD. To train child and adolescent mental health services (CAMHS) therapists to deliver cognitive therapy for SAD in adolescents (CT-SAD-A) and assess therapist competence. To estimate the costs to the NHS of training therapists to deliver CT-SAD-A and the mean cost per adolescent treated. To examine the feasibility of a randomised controlled trial (RCT) to compare CT-SAD-A with the general form of cognitive-behavioural therapy that is more commonly used. During the training phase of the study, it became clear that the RCT would not be feasible because of high staff turnover and unfilled posts within CAMHS and changes in the nature of referrals, which meant that few young people with primary SAD were accessing some of the participating services. The study design was altered to comprise the following: a training case series of CT-SAD-A delivered in routine CAMHS, an estimate of the cost to the NHS of training therapists to deliver CT-SAD-A and of the mean cost per adolescent treated, and qualitative interviews with participating young people, parents, therapists and service managers/leads. Five CAMHS teams within Berkshire Healthcare and Oxford Health NHS Foundation Trusts. Eight therapists received training in CT-SAD-A. Twelve young people received CT-SAD-A, delivered by six therapists. Six young people, six parents, seven therapists and three managers participated in qualitative interviews. Cognitive therapy for social anxiety disorder in adolescents (CT-SAD-A). Measured outcomes included social anxiety symptoms and diagnostic status, comorbid symptoms of anxiety and depression, social and general functioning, concentration in class and treatment acceptability. Patient level utilisation of the intervention was collected using clinicians' logs. Nine out of 12 participants achieved good outcomes across measures (r ≥ 0.60 across social anxiety measures). The estimated cost of delivering CT-SAD-A was £1861 (standard deviation £358) per person. Qualitative interviews indicated that the treatment was acceptable to young people, parents and therapists, but therapists and managers experienced challenges when implementing the training and treatment within the current CAMHS context. Findings were based on a small, homogeneous sample and there was no comparison arm. CT-SAD-A is a promising treatment for young people with SAD, but the current CAMHS context presents challenges for its implementation. Further work is needed to ensure that CAMHS can incorporate and test CT-SAD-A. Alternatively, CT-SAD-A should be delivered and tested in other settings that are better configured to treat young people whose lives are held back by SAD. The new schools Mental Health Support Teams envisaged in the 2017 Children's Mental Health Green Paper may provide such an opportunity. The National Institute for Health Research (NIHR) Health Technology Assessment programme. Individual funding was also provided for Cathy Creswell, David M Clark and Eleanor Leigh as follows: NIHR Research Professorship (Cathy Creswell); Wellcome Senior Investigator Award (Anke Ehlers and David M Clark); and the Wellcome Clinical Research Training Fellowship (Eleanor Leigh).

Cost competitive analysis of large-scale gold mines in Ghana from 2007 to 2016

The gold mining industry is a major contributor to the economy of Ghana. However, this contribution has been declining over the past decade. This decline coupled with the importance of the industry to the country’s economy necessitated the need to analyse the performance of companies within the industry. Therefore, a cost performance analysis of Ghana’s major gold mines was done in this paper for the period 2007 to 2016 using industry cost curves. A correlation coefficient analysis was also done to identify the key cost drivers in Ghana. This paper further analysed the cost competitiveness of Ghana’s gold mining industry against other gold producing countries in the world. From the analysis, it was found that Newmont’s Ahafo and Akyem mines were consistent low unit cost producers. Both mines benefited from economies of scale and high metallurgical recovery rates. On the other hand, AngloGold Ashanti’s Obuasi and Golden Star’s Bogoso mines were found to be consistent high unit cost producers due to low-productive and labour-intensive underground mining methods used and very low metallurgical recovery rates, respectively. Finally, the study revealed that Ghana’s gold mining industry was not cost competitive when compared to other gold-producing countries over the analysis period.

Evaluation on a Simultaneous Analytical Method of Pesticide Residues in Limes

A LC-MS/MS simultaneous analytical method for screening 191 pesticide residues in limes had been developed and validated. Pesticides were extracted with acetonitrile from samples. Then mixed salts, which were anhydrous magnesium sulfate for dehydration, sodium carbonate for adjusting pH, and sodium chloride for salting out, were added to the sample. After centrifugation, supernatant was transferred to a tube. The sample solution was cleaned up using solid phase extraction (SPE) with C18/GC/PSA for the determination by LC-MS/MS. The developed method was improved the recovery rate of thiabendazole, which had a low recovery rate by the conventional method. Validation study, which was following the guidelines of the Ministry of Health, Labor and Welfare, were carried out at 0.01 and 0.1 μg g-1 to evaluate the method. The results of 175 pesticides out of 191 were with satisfactory. A total of 19 imported lime samples sold in Tokyo was analyzed to evaluate the method, then 18 samples contained pesticide residues below MRLs. The developed method is applicable for detection of pesticide residues in lime.

Injection-production optimization of carbonate reservoir based on an inter-well connectivity model

Carbonate reservoirs are highly heterogeneous. During waterflooding stage, the channeling phenomenon of displacing fluid in high-permeability layers easily leads to early water breakthrough and high water-cut with low recovery rate. To quantitatively characterize the inter-well connectivity parameters (including conductivity and connected volume), we developed an inter-well connectivity model based on the principle of inter-well connectivity and the geological data and development performance of carbonate reservoirs. Thus, the planar water injection allocation factors and water injection utilization rate of different layers can be obtained. In addition, when the proposed model is integrated with automatic history matching method and production optimization algorithm, the real-time oil and water production can be optimized and predicted. Field application demonstrates that adjusting injection parameters based on the model outputs results in a 1.5% increase in annual oil production, which offers significant guidance for the efficient development of similar oil reservoirs. In this study, the connectivity method was applied to multi-layer real reservoirs for the first time, and the injection and production volume of injection-production wells were repeatedly updated based on multiple iterations of water injection efficiency. The correctness of the method was verified by conceptual calculations and then applied to real reservoirs. So that the oil field can increase production in a short time, and has good application value.

Evaluation of the relationship between VRK2, rs4380187 polymorphisms, and genetic susceptibility to schizophrenia in the Chinese Han population.

Schizophrenia (SZ) is a serious hereditary mental disease with a low recovery rate, especially due to the lack of understanding about the cause of the disease. VRK2 is considered to be related to the pathogenesis of schizophrenia. In this study, we analyzed the correlation between VRK2, rs4380187 single-nucleotide polymorphism (SNP), and schizophrenia. Peripheral blood DNA was extracted using a genomic DNA extraction kit. The DNA samples were genotyped using the Agena MassARRAY platform, and four genetic models were applied to compute the odds ratios (ORs) and 95% confidence intervals (CIs) using unconditional logistic regression. The p value was obtained by the chi-square and t test for independent samples. The C allele of rs4380187 SNP was significantly (p = 0.008) associated with decreased risk of SZ. The AA genotype of rs4380187 showed significantly (p = 0.009) lower frequency in cases with SZ than in controls and was associated with decreased risk of the disease. The frequency of the CA genotype of rs4380187 correlated with a 0.73-fold decreased risk of SZ (p = 0.033). In the co-dominant genetic model, the genotype of rs4380187 was associated with a decreased risk of SZ (p = 0.010). We also found that the log-additive model of rs4380187 significantly reduced the risk of SZ disease (p = 0.007). This study provides further evidence that rs4380187 SNP is associated with SZ. This genotype variation could be associated with the psychopathology and cognitive function in SZ.

Announcements

Solid-phase extraction is widely used for the extraction and purification of a wide range of compounds, but severe problems such as a low recovery rate, low degree of purification, and poor reproducibility might occur on the solid-phase extraction of water-soluble compounds in aqueous solutions. To solve these problems, hydrophilic-lipophilic balanced-type extractants which were synthesized by co-polymerization with hydrophobic monomer and hydrophilic monomers have been developed. It is estimated that the wettability is improved by an introduced hydrophilic group on the hydrophobic resin, and thus better extraction properties for the water-soluble compounds are obtained. The extraction properties and the purification degree by the solid-phase extraction depend on the chemical and physical properties of solidphase extractants, such as chemical structure, pore properties and residual functional groups. The authors synthesized solid-phase extractants having hydrophilic groups with different compositions and pore properties in house to evaluate effects of these chemical and physical properties of solid-phase extractants on the extraction properties of the water-soluble compounds. In this paper, the extraction characteristics for water-soluble compounds on the developed solid phase extractants having hydrophilic groups for reversed-phase mode and hydrophilic interaction mode are reviewed.

Development of Solid-phase Extractants Having Hydrophilic Groups and Their Extraction Characteristics for Water-soluble Compounds

Solid-phase extraction is widely used for the extraction and purification of a wide range of compounds, but severe problems such as a low recovery rate, low degree of purification, and poor reproducibility might occur on the solid-phase extraction of water-soluble compounds in aqueous solutions. To solve these problems, hydrophilic-lipophilic balanced-type extractants which were synthesized by co-polymerization with hydrophobic monomer and hydrophilic monomers have been developed. It is estimated that the wettability is improved by an introduced hydrophilic group on the hydrophobic resin, and thus better extraction properties for the water-soluble compounds are obtained. The extraction properties and the purification degree by the solid-phase extraction depend on the chemical and physical properties of solid-phase extractants, such as chemical structure, pore properties and residual functional groups. The authors synthesized solid-phase extractants having hydrophilic groups with different compositions and pore properties in house to evaluate effects of these chemical and physical properties of solid-phase extractants on the extraction properties of the water-soluble compounds. In this paper, the extraction characteristics for water-soluble compounds on the developed solid phase extractants having hydrophilic groups for reversed-phase mode and hydrophilic interaction mode are reviewed.

Research on Mining Technology of Steeply Inclined Thin Ore Body in High-grade Content Mine

In view of the problems of poor mining safety, low recovery efficiency, high cost, low recovery rate and few recovery options in steeply inclined, extremely unstable thin to medium-thick ore bodies, especially there are no economically feasible mining options for low-grade resources of this type of deposit Difficult problem. The paper proposes a safe, high-efficiency and low-cost mining technology suitable for steeply inclined thin ore bodies-segmented empty field subsequent filling mining method combined with 3Dmine and ANSYS to establish a FLAC3D numerical model to obtain a stope production capacity of 180t/d and a loss rate of 7.40%, the expected effect of the dilution rate of 14.96%.

Determination of nine N-nitrosamines in animal derived foods by QuEChERS-isotope dilution combined with gas chromatography-tandem mass spectrometry

建立了同时测定动物源性食品中9种N-亚硝胺类化合物的气相色谱-串联质谱分析方法。当下动物源性食品中N-亚硝胺类化合物污染种类较多,对人体危害较大,但国标GB 5009.26-2016仅针对N-二甲基亚硝胺的检测,且存在样品前处理复杂、标准方法回收率低、再现性差等问题,因此建立同时快速检测多种N-亚硝胺类化合物的方法有一定现实意义。称取10.0 g样品,置于50 mL离心管中,加入200 μL内标工作液和10 mL乙腈,冷冻30 min后,加入4 g硫酸镁和1 g氯化钠进行脱水,以9000 r/min离心5 min。取5 mL上清液使用150 mg聚苯乙烯二乙烯苯(PLS-A)粉末净化,再使用1.6 g MgSO4和0.4 g NaCl脱水,过0.22 μm滤膜,上机分析。在初始温度为50 ℃时采用程序升温模式,0.16 min后,以900 ℃/min的速率将温度升至220 ℃。采用毛细管气相色谱柱HP-Innowax(30 m×0.25 mm×0.25 μm)分离,使用电子轰击电离(EI)源检测,在多反应监测模式下,以保留时间和特征离子对信息进行定性和定量分析,使用内标法定量N-亚硝胺类化合物。结果表明,N-亚硝胺类化合物在0.1~50.0 μg/L范围内具有良好的线性关系,方法的检出限(S/N=3)和定量限(S/N=10)分别为0.03~0.30 μg/kg和0.10~1.00 μg/kg。对不同样品基质进行0.5、1.0、3.0 μg/kg3个水平的加标回收试验,9种N-亚硝胺类化合物的回收率为80.4%~98.5%, RSD(n=6)为2.41%~12.50%。应用建立的方法检测市面上常见的动物源性食品,除N-亚硝基乙胺、N-亚硝基吗啡胆碱外,其他7种N-亚硝胺类化合物均有不同程度检出。检测结果表明,腌制水产品中N-亚硝胺类化合物含量普遍高于其他样品。研究建立的方法操作简单,不需要长时间蒸馏提取,可快速对动物源性食品中N-亚硝胺类化合物进行定性和定量分析,且样品和试剂的消耗量更少,节省成本,对环境污染小。该法的建立对我国动物源性食品中N-亚硝胺类化合物残留水平的控制、检测标准的制定和采取相应的管理措施具有一定的理论和现实意义。

A SIRD epidemic model with community structure.

The study of epidemics spreading with community structure has become a hot topic. The classic SIR epidemic model does not distinguish between dead and recovered individuals. It is inappropriate to classify dead individuals as recovered individuals because the real-world epidemic spread processes show different recovery rates and death rates in different communities. In the present work, a SIRD epidemic model with different recovery rates is proposed. We pay more attention to the changes in the number of dead individuals. The basic reproductive number is obtained. The stationary solutions of a disease-free state and an endemic state are given. We show that quarantining communities can decrease the basic reproductive number, and the total number of dead individuals decreases in a disease-free steady state with an increase in the number of quarantined communities. The most effective quarantining strategy is to preferentially quarantine some communities/cities with a greater population size and a fraction of initially infected individuals. Furthermore, we show that the population flows from a low recovery rate and high population density community/city/country to some high recovery rate and low population density communities/cities/countries, which helps to reduce the total number of dead individuals and prevent the prevalence of epidemics. The numerical simulations on the real-world network and the synthetic network further support our conclusions.

Rare bioparticle detection via deep metric learning.

Recent deep neural networks have shown superb performance in analyzing bioimages for disease diagnosis and bioparticle classification. Conventional deep neural networks use simple classifiers such as SoftMax to obtain highly accurate results. However, they have limitations in many practical applications that require both low false alarm rate and high recovery rate, e.g., rare bioparticle detection, in which the representative image data is hard to collect, the training data is imbalanced, and the input images in inference time could be different from the training images. Deep metric learning offers a better generatability by using distance information to model the similarity of the images and learning function maps from image pixels to a latent space, playing a vital role in rare object detection. In this paper, we propose a robust model based on a deep metric neural network for rare bioparticle (Cryptosporidium or Giardia) detection in drinking water. Experimental results showed that the deep metric neural network achieved a high accuracy of 99.86% in classification, 98.89% in precision rate, 99.16% in recall rate and zero false alarm rate. The reported model empowers imaging flow cytometry with capabilities of biomedical diagnosis, environmental monitoring, and other biosensing applications.