Distributed Subgradient Method With Random Quantization and Flexible Weights: Convergence Analysis.

The distributed subgradient (DSG) method is a widely used algorithm for coping with large-scale distributed optimization problems in machine-learning applications. Most existing works on DSG focus on ideal communication between cooperative agents, where the shared information between agents is exact and perfect. This assumption, however, can lead to potential privacy concerns and is not feasible when wireless transmission links are of poor quality. To meet this challenge, a common approach is to quantize the data locally before transmission, which avoids exposure of raw data and significantly reduces the size of the data. Compared with perfect data, quantization poses fundamental challenges to maintaining data accuracy, which further impacts the convergence of the algorithms. To overcome this problem, we propose a DSG method with random quantization and flexible weights and provide comprehensive results on the convergence of the algorithm for (strongly/weakly) convex objective functions. We also derive the upper bounds on the convergence rates in terms of the quantization error, the distortion, the step sizes, and the number of network agents. Our analysis extends the existing results, for which special cases of step sizes and convex objective functions are considered, to general conclusions on weakly convex cases. Numerical simulations are conducted in convex and weakly convex settings to support our theoretical results.

Unprecedented spirodioxynaphthalenes from the endophytic fungus Phyllosticta ligustricola HDF-L-2 derived from the endangered conifer Pseudotsuga gaussenii.

Four undescribed palmarumycin-type spirodioxynaphthalenes (phyligustricins A-D) and a known biogenetic precursor (palmarumycin BG1) were isolated from a solid fermentation of Phyllosticta ligustricola HDF-L-2, an endophyte associated with the endangered Chinese conifer Pseudotsuga gaussenii. The structures were elucidated by spectroscopic methods, single-crystal X-ray diffraction analyses, and electronic circular dichroism calculations. Both phyligustricins A and B have an unprecedented spirodioxynaphthalene-derived skeleton containing an extra 4H-furo [3,2-c]pyran-4-one moiety, while phyligustricins C and D are p-hydroxy-phenethyl substituted spirodioxynaphthalenes. The plausible biosynthetic relationships of the isolates were briefly proposed. Phyligustricins C and D and palmarumycin BG1 showed considerable antibacterial activity against Staphylococcus aureus, each with an MIC value of 16 µg/mL. Palmarumycin BG1 displayed significant inhibitory effects against ACL and ACC1, with IC50 values of 1.60 and 8.00 µM, respectively.

Towards Large-Scale and Privacy-Preserving Contact Tracing in COVID-19 Pandemic: A Blockchain Perspective.

Activity-tracking applications and location-based services using short-range communication (SRC) techniques have been abruptly demanded in the COVID-19 pandemic, especially for automated contact tracing. The attention from both public and policy keeps raising on related practical problems, including 1) how to protect data security and location privacy? 2) how to efficiently and dynamically deploy SRC Internet of Thing (IoT) witnesses to monitor large areas? To answer these questions, in this paper, we propose a decentralized and permissionless blockchain protocol, named Bychain. Specifically, 1) a privacy-preserving SRC protocol for activity-tracking and corresponding generalized block structure is developed, by connecting an interactive zero-knowledge proof protocol and the key escrow mechanism. As a result, connections between personal identity and the ownership of on-chain location information are decoupled. Meanwhile, the owner of the on-chain location data can still claim its ownership without revealing the private key to anyone else. 2) An artificial potential field-based incentive allocation mechanism is proposed to incentivize IoT witnesses to pursue the maximum monitoring coverage deployment. We implemented and evaluated the proposed blockchain protocol in the real-world using the Bluetooth 5.0. The storage, CPU utilization, power consumption, time delay, and security of each procedure and performance of activities are analyzed. The experiment and security analysis is shown to provide a real-world performance evaluation.

Liriogerphines A-D, a Class of Sesquiterpene-Alkaloid Hybrids from the Rare Chinese Tulip Tree Plant.

Liriogerphines A-D (1-4, respectively), an unprecedented class of hybrids of germacranolide-type sesquiterpenoids and aporphine-type alkaloids, were isolated from the rare medicinal plant Liriodendron chinense. Their structures were elucidated by comprehensive spectroscopic analyses combined with electronic circular dichroism calculations and X-ray crystallographic data. Biosynthetically, an aza-Michael addition reaction is proposed to be involved in the assemblies of this class of hybrids. Compound 4 exhibited cytotoxicity against leukemia cells via inducing apoptosis and inhibiting Bcl-2 expression.

Study on Secondary Metabolites of Endophytic Fungus, Aspergillus fumigatus, from Crocus sativus L. Guided byUHPLC-HRMS/MS-Based Molecular Network.

As a traditional Chinese medicine, Crocus sativus Linn has been used for a long time in China. However, the studies on secondary metabolites of its endophytic fungi were not fully sufficient. Thus, the endophytic fungus, Aspergillus fumigatus, collected from the lateral buds of C. sativus, was here investigated. An approach combining UHPLC-HRMS/MS (ultra-high performance liquid chromatography-high resolution mass spectrometry) with molecular network was carried out to construct a molecular network of crude EtOAc extract (CEE) of A. fumigatus, in which 32 chemical compounds were annotated. On the basis of analysis results, a total of 15 known natural compounds were isolated from CEE. Among them, compounds 11 and 12 were isolated for the first time from the genus Aspergillus. Moreover, CEE and compound 7 exhibited moderate inhibitory activity against Erwinia sp. with a MIC value of 100 µg/mL. This study provided a more convenient and rapid approach to investigating the crude extract with complex components of A. fumigatus, which is of great benefit to the further study and utilization of secondary metabolites of the genus Aspergillus.

Structurally diverse glycosides of secoiridoid, bisiridoid, and triterpene-bisiridoid conjugates from the flower buds of two Caprifoliaceae plants and their ATP-citrate lyase inhibitory activities.

The ethanolic extracts of the dried flower buds of two Caprifoliaceae plants, Lonicera japonica and Abelia × grandiflora, showed considerable inhibitory activities against adenosine triphosphate (ATP)-citrate lyase (ACL), a new promising drug target for the treatment of metabolic disorders. Bioassay-guided purification in conjunction with HPLC-PDA profiling led to the isolation and characterization of thirty-five (1-35) and fourteen (1'-14') structurally diverse compounds from the above two plant extracts, respectively. Compounds 1-9 and 1'-6' are previously undescribed glycosides. Their structures were elucidated on the basis of spectroscopic data, electronic circular dichroism (ECD), and single crystal X-ray diffraction analyses. In particular, lonicejaposide A (1) has an unprecedented skeleton generated through the coupling of C-7 in secologanin with C-2'' in phenylacetaldehyde via an aldol condensation. Abeliflorosides A (1') and B (2') are hitherto unknown glycosides of triterpene and bisiridoid conjugates constructed through the formation of a 1,3-dioxane moiety. All the isolates were evaluated for their inhibitory activities against ACL. Compounds 9, 25-28, 31, 1', 2', and 14' displayed significant inhibitory effects, with IC50 values ranging from 0.1 to 14.2 µM. The interactions of selected compounds possessing different structure features (e.g., 9, 25, 31, and 2') with ACL were thereafter performed by employing molecular docking studies. In addition, compound 2', the most complex triterpene-bisiridoid conjugate glycoside reported herein, also inhibited acetyl-CoA carboxylase 1 (ACC1), with an IC50 value of 7.9 µM. The dried material of the flower buds of L. japonica (honeysuckle) is a well-known traditional oriental medicine (i.e., Flos Lonicerae Japonicae, FLJ) and has long been used in large quantities. The above findings not only provide new insights for the development of multipurpose utilization of FLJ in healthcare community, but also provide profitable clues indicating that the flower buds of A. × grandiflora might be a potential alternative to FLJ in the traditional Chinese medicine market.

A new indole alkaloid from the stems of Glycosmis puberula var. craibii.

A phytochemical investigation on the stems of Glycosmis puberula var. craibii led to the isolation of a new indole alkaloid (named glycosmiscrol A, 1), together with four known compounds (2-5). The new structure was elucidated by detailed analysis of comprehensive spectroscopic methods. All isolated compounds were evaluated for their antiproliferative activities against five human cancer cell lines: HL-60, SMMC-7721, A-549, MCF-7 and SW480 in vitro. Compounds 1-5 showed significant antiproliferative effects with IC50 values ranging from 0.16 to 8.58 µM.

Indole Alkaloids from a Soil-Derived Clonostachys rosea.

Clonorosins A (1) and B (2), two novel indole alkaloids featuring unprecedented 6/5/6/6/5 and 6/5/5 cores, together with seven known indole-linked 2,5-diketopiperazine alkaloids (3-9), were isolated from the soil-derived fungus Clonostachys rosea YRS-06. The new structures were proposed through HR-MS, NMR, and ECD spectroscopic data. They were established by comparing the calculated NMR, ECD, and specific rotation data with the experimental. To assist in determining the absolute configuration of the chiral carbon in the side chain of 2,5-diketopiperazine derivatives, flexible analogues 3i-3iv were synthesized and analyzed. 1 was active against Fusarium oxysporum with an MIC value of 50 µg/mL. 7 and 8 showed excellent activity against human HeLa and HepG2 cells with IC50 values of 0.12-0.60 µM.

Highly Oxygenated Triterpenoids and Diterpenoids from Fructus Rubi (Rubus chingii Hu) and Their NF-kappa B Inhibitory Effects.

During a phytochemical investigation of the unripe fruits of Rubus chingii Hu (i.e., Fructus Rubi, a traditional Chinese medicine named "Fu-Pen-Zi"), a number of highly oxygenated terpenoids were isolated and characterized. These included nine ursane-type (1, 2, and 4-10), five oleanane-type (3, 11-14), and six cucurbitane-type (15-20) triterpenoids, together with five ent-kaurane-type diterpenoids (21-25). Among them, (4R,5R,8R,9R,10R,14S,17S,18S,19R,20R)-2,19α,23-trihydroxy-3-oxo-urs-1,12-dien-28-oic acid (rubusacid A, 1), (2R*,4S*,5R*,8R*,9R*,10R*,14S*,17S*, 18S*,19R*,20R*)-2α,19α,24-trihydroxy-3-oxo-urs-12-en-28-oic acid (rubusacid B, 2), (5R,8R,9R,10R, 14S,17R,18S,19S)-2,19α-dihydroxy-olean-1,12-dien-28-oic acid (rubusacid C, 3), and (3S,5S,8S,9R, 10S,13R,16R)-3α,16α,17-trihydroxy-ent-kaur-2-one (rubusone, 21) were previously undescribed. Their chemical structures and absolute configurations were elucidated on the basis of spectroscopic data and electronic circular dichroism (ECD) analyses. Compounds 1 and 3 are rare naturally occurring pentacyclic triterpenoids featuring a special α,ß-unsaturated keto-enol (diosphenol) unit in ring A. Cucurbitacin B (15), cucurbitacin D (16), and 3α,16α,20(R),25-tetrahydroxy-cucurbita-5,23- dien-2,11,22-trione (17) were found to have remarkable inhibitory effects against NF-κB, with IC50 values of 0.08, 0.61, and 1.60 µM, respectively.

A new coumarin derivative from the stems of the endangered plant Ulmus elongata.

A preliminary phytochemical investigation of the stems of the endangered plant Ulmus elongata led to the isolation of a new coumarin derivative (named ulmuselactone A, 1) and eight known compounds (2-9). The new structure was elucidated by detailed analysis of comprehensive spectroscopic methods, and its absolute configuration was established by comparing experimental and calculated electronic circular dichroism (ECD) spectra. The isolated compounds were evaluated for their antibacterial activities.

Beshanzoides A-D, unprecedented cycloheptanone-containing polyketides from Penicillium commune P-4-1, an endophytic fungus of the endangered conifer Abies beshanzuensis.

A number of previously undescribed (1-7) and structurally related known (8-17) isobenzofuran-type polyketides were obtained from the fermentation of Penicillium commune P-4-1, an endophytic fungus isolated from the fresh trunk bark of the critically endangered conifer Abies beshanzuensis. Beshanzoides A-D (1-4, resp.) feature a cycloheptanone-containing isobenzofuran ring system hitherto unknown, which might be biosynthesized via two steps of aldol reactions starting from a common co-occurring isobenzofuran-type polyketide as the precursor. The new structures were elucidated by spectroscopic methods, electronic circular dichroism data, and single crystal X-ray diffraction analyses. Beshanzoide E (5) showed antimicrobial activity (MIC: 16 µg mL-1) against Staphylococcus aureus, whereas (±)-strobide A (10) inhibited (MIC: 16 µg mL-1) Candida albicans. Cyclopaldic acid (12) and 3-O-methyl-cyclopaldic acid (13) exhibited inhibitory effects against acetyl-CoA carboxylase 1 (ACC1) with IC50 values of 0.96 and 11.77 µM, respectively. Compound 12 also inhibited (IC50: 7.56 µM) ATP-citrate lyase (ACL).

Macrocyclic Pyridone Pentamers for Highly Selective High-Capacity Removal of Caesium Ions from Radioactive High-Salinity Waste.

We report here that macrocyclic H-bonded pyridone pentamers, containing five properly and convergently spaced electron-rich O-atoms that decorate a rigid cavity of 2.85 Šacross, exhibit an extraordinarily high yet pH-independent capacity and selectivity in Cs+ removal. In particular, with [host]=240 µM and [Cs+ ]=15 µM, a single extraction efficiently removes more than 91% of Cs+ ions from artificial sea water, containing various competitive metal ions at a total concentration of 0.68 M ([total Mn+ ]/[Cs+ ]=4.5×104 ]). To our best knowledge, these pyridone pentamers represent the best small organic molecule-based extractants that target Cs+ ions.

Effects of extreme meteorological factors on daily mumps cases in Hefei, China, during 2011-2016.

Mumps remains one of the worldwide major health problems over the past decade. Seasonal variations of mumps indicate that meteorological factors play an important role in the development of mumps, but few studies have investigated the relationship between extreme meteorological factors and the incidence of mumps. Daily mumps cases and meteorological factors in Hefei, China, from 2011 to 2016 were obtained. A generalized additive model combined with the distributed lag nonlinear model (DLNM) was used to quantify the risk of extreme meteorological factors on mumps incidence. Nonlinear relationships were observed among all meteorological factors and mumps incidence. We found that extremely low and high temperatures increased the risk of mumps. The relative risks (RRs) of the cumulative effects along 30 lag days were 2.02 (95%CI: 1.14-3.56) and 2.42 (95%CI: 1.37-4.24), respectively. Both short and long sunshine duration had negative correlation on mumps, with cumulative RRs of 0.64 (95%CI: 0.46-0.92) and 0.57 (95%CI: 0.44-0.74), respectively. In the subgroup analysis, males were found to be more sensitive to extreme weather, especially extreme temperatures and sunshine duration. This study suggests that extreme meteorological factors, especially extreme temperatures and sunshine duration, exert a significant impact on the incidence of mumps. When formulating and implementing effective strategies to the prevention and control of mumps, authorities should take the effect caused by extreme meteorological factors into consideration and pay more attention to susceptible populations, such as male children and teenagers.

Effect of the Interaction Between Cadmium Exposure and CLOCK Gene Polymorphisms on Thyroid Cancer: a Case-Control Study in China.

The exposure to endocrine disruptors and the disruption of the circadian rhythms can both affect thyroid hormones, with results that are most likely carcinogenic in humans. The effects of cadmium (Cd) level and circadian-related single-nucleotide polymorphisms (SNPs) on thyroid cancer (TC) risk have rarely been reported. In this study, the associations of urine Cd, CLOCK gene polymorphisms, and TC risk were evaluated, in addition to the effect of the gene-environment interaction on TC risk. In this case-control study, 218 TC cases and 218 controls were enrolled. Cd in urinary samples was determined by atomic absorption spectrometry. Three SNPs (rs3805151, rs3805154, and rs78929565) were genotyped with an improved multiplex ligation detection reaction technique. The individuals with a high Cd level were 1.72-fold more likely to have TC (OR = 1.72, 95%CI 1.04-2.85), and a high Cd level was associated with higher tumor T stage and N stage (OR = 2.42, 95%CI 1.28-4.58; OR = 3.26, 95%CI 1.67-6.33, respectively). Individuals with TT genotype of rs78929565 had a 107 % increase in TC risk (OR = 2.07, 95%CI 1.00-4.29). Cases with CT genotype tended to have a higher AJCC stage (OR = 2.79, 95% CI 1.01-7.78). A significant interaction was detected between the rs78929565 variant and Cd exposure (p interaction = 0.04). The TT genotype carriers of rs78929565 with a high Cd level were more susceptible to thyroid cancer than the major homozygotes carriers who were exposed to a low cadmium level (OR = 2.66, 95%CI 1.07-6.59). These findings suggested that Cd exposure and the CLOCK variant genotypes were associated with TC risk and tumor severity. Individuals with minor allele of rs78929565 and higher Cd exposure had increased susceptibility to TC. Further studies are required to confirm these findings.

Urinary Metal Concentrations and the Incidence of Hypertension Among Adult Residents Along the Yangtze River, China.

Metals from the natural environment have potential hypertension effects. However, relevant studies on this topic are few. A total of 1358 adults aged 18-74 years from Chizhou, Maanshan, and Tongling of Anhui Province participated in the baseline study from 2014 to 2015. The follow-up study was performed from 2016 to 2017. Inductively coupled plasma optical emission spectrometry (7000 DV) was used to measure urinary Cr, Mn, Fe, Cu, and Zn of residents. Urinary concentrations of Cd determined via TAS-900 atomic absorption spectrophotometry at 228.8 nm wavelength. A total of 275 hypertension cases were identified. After adjusting for sociodemographic factors and risk factors for hypertension, four metals (Cd, Cr, Cu, and Mn) were significantly associated with hypertension in the single-metal model. Upon including all metals in the same model, the hazard ratios of the highest quartiles Cd and Cu compared with the reference group were 1.42 (95% confidence interval [CI] 1.09-2.02) and 1.56 (95% CI 1.16-2.09) for cases of hypertension. Our findings suggested that high levels of Cd and Cu might increase the incidence of hypertension. Further studies involving larger population should be conducted to confirm these findings.

Professional identity and mental health of rural-oriented tuition-waived medical students in Anhui Province, China.

BACKGROUND: The shortage of primary care physicians in rural China is an enduring problem with serious implications for access to care. In response to the shortage in health workforce in rural areas, China government has launched the rural-oriented tuition-waived medical education (RTME) programme since 2010, aiming to train more general practitioners to address the rural health workforce requirements in middle and west areas. This study aims to investigate the prevalence of mental illness and the level of professional identity in the rural-oriented tuition-waived medical students (RTMSs), and to explore the impact of the RTMSs' professional identity and related cognition and satisfaction with the RTME programme on mental health. METHODS: We conducted a descriptive, cross-sectional study. A total of 1103 RTMSs and 1095 non-oriented medical students from seven medical universities (colleges) in Anhui province completed a demographic questionnaire, the Depression, Anxiety, Stress Scales and the Professional Identity Questionnaire for Undergraduate Students. Cognition and satisfaction with the RTME programme of the RTMSs were collected. Multiple linear regression analysis was used to analyze the data. RESULTS: The prevalence of depression, anxiety, and stress in RTMSs were 11.8, 22.9 and 3.4%, respectively. The mean total scores of the Professional Identity Questionnaire for Undergraduate Students were 3.58 (SD = 0.61). Results of multiple linear regression model indicated that students who are dissatisfied with targeted primary healthcare institution are likely to suffer from depression and anxiety; moreover, students who enrolled in the rural-oriented tuition-waived medical education programme due to economic reason are more likely to suffer from anxiety. Furthermore, a significant positive correlation was found between professional identity and mental health. CONCLUSIONS: Providing better information about the RTME programme prior to enrollment and improving the students' cognition of the policy's effectiveness and the social value of rural healthcare work may contribute to improving the professional identity of the RTMSs. Meanwhile, a significant positive association was found between professional identity and mental health. This is a new perspective that shows that developing and improving professional identity may help medical students reduce the risk of psychological illness.

Fasting serum glucose, thyroid-stimulating hormone, and thyroid hormones and risk of papillary thyroid cancer: A case-control study.

BACKGROUND: This study was to investigate the association of fasting serum glucose (FSG), thyroid-stimulating hormone (TSH), and thyroid hormones with papillary thyroid cancer (PTC). METHODS: A total of 649 participants were included in this case-control study. The associations of FSG, TSH, free triiodothyronine (FT3) and free thyroxine (FT4) with PTC were estimated using an unconditional logistic regression. RESULTS: Compared with the lowest quintile of TSH levels, odds ratios (ORs) and 95% confidence intervals (CIs) for association between PTC risk and highest quintile of TSH levels were 1.67 (95% CI, 0.99-2.83). However, this risk correlation was more significant in PTC cases with ≤1.0 cm tumor size (adjusted OR, 1.95; 95% CI, 1.08-3.54; adjusted P-trend, 0.05). The PTC risk was also inversely associated with the serum FT3 level in all participants (adjusted P-trend, 0.001), but positively associated with the serum FT4 (adjusted P-trend, 0.001) and FSG (adjusted P-trend, 0.01) levels. Among the participants without diabetes, the individuals with high FSG levels and abnormal TSH concentration had an increased PTC risk (adjusted OR, 3.38; 95% CI, 1.78-6.42). CONCLUSION: The current study provides evidence for the association of FSG, TSH, and thyroid hormones (FT3 and FT4) with PTC risk. However, larger relative studies are needed.

Isolation, Identification, and Activity Evaluation of Chemical Constituents from Soil Fungus Fusarium avenaceum SF-1502 and Endophytic Fungus Fusarium proliferatum AF-04.

Fusarium, a large genus of filamentous fungi, is widely distributed in soil and plants. Fusarium is a prolific source of novel chemical constituents with various bioactivities. In search for antibiotics from soil and endophytic fungi, the secondary metabolites of Fusarium avenaceum SF-1502 and Fusarium proliferatum AF-04 were investigated. An alkaloid (1), a depsipeptide (6), and five sesquiterpenoids (7-11) were isolated from the extracts of the soil fungus F. avenaceum SF-1502. Three alkaloids (2-4), a depsipeptide (5), three sesquiterpenoids (9, 11, and 12), a sesterterpene (13), and four 1,4-naphthoquinones (14-17) were also separated from the extract of the green Chinese onion derived fungus F. proliferatum AF-04. Fusaravenin (1) represents the first example of a natural naphthoisoxazole-type zwitter-ionic alkaloid, a naphthoisoxazole formic acid connected with a morpholino carbon skeleton. Cyclonerotriol B (7) is a new cyclonerane sesquiterpene. Another new sesquiterpene, 3ß-hydroxy-ß-acorenol (12), possesses an acorane framework. The known compounds 9 and 11 were found from both fungi. The structures of the new compounds were determined via extensive HR-ESI-MS and comparison between experimental and calculated NMR results. The biological properties of 1-5 and 7-17 were evaluated against eight anthropogenic bacteria, while 1 and 7-11 were also screened for inhibitory effects against four plant pathogen bacteria. The known compounds 8, 9, and 14-17 showed potent antibacterial activities toward some of the tested anthropogenic bacteria.

User Participation in Collaborative Filtering-Based Recommendation Systems: A Game Theoretic Approach.

Collaborative filtering is widely used in recommendation systems. A user can get high-quality recommendations only when both the user himself/herself and other users actively participate, i.e., provide sufficient ratings. However, due to the rating cost, rational users tend to provide as few ratings as possible. Therefore, there exists a tradeoff between the rating cost and the recommendation quality. In this paper, we model the interactions among users as a game in satisfaction form and study the corresponding equilibrium, namely satisfaction equilibrium (SE). Considering that accumulated ratings are used for generating recommendations, we design a behavior rule which allows users to achieve an SE via iteratively rating items. We theoretically analyze under what conditions an SE can be learned via the behavior rule. Experimental results on Jester and MovieLens data sets confirm the analysis and demonstrate that, if all users have moderate expectations for recommendation quality and satisfied users are willing to provide more ratings, then all users can get satisfying recommendations without providing many ratings. The SE analysis of the proposed game in this paper is helpful for designing mechanisms to encourage user participation.