关注长江水质——“绿行之踪”社会实践

2018年和2019年小学期,厦门大学本科生“绿行之踪”社会实践队赴重庆、上海等长江流域主要城市进行社会实践活动,采集了当地的水样,测定了水样中的磷酸根含量和高锰酸盐指数,同时进行了水资源保护的宣传活动和网络问卷调查。

The contribution of small and large sensory afferents to postural control in patients with peripheral neuropathy

Peripheral neuropathy(PN) is a multifarious disorder that is caused by damage to the peripheral nerves. Although the symptoms of PN vary with the etiology, most cases are characterized by impaired tactile and proprioceptive sensation that progresses in a distal to proximal manner. Balance also tends to deteriorate as the disorder becomes more severe, and those afflicted are substantially more likely to fall while walking compared with those who are healthy. Most patients with PN walk more cautiously and with greater stride variability than age-matched controls, but the majority of their falls occur when they must react to a perturbation such as a slippery or uneven surface. The purpose of this study was to first describe the role of somatosensory feedback in the control of posture and then discuss how that relationship is typically affected by the most common types of PN. A comprehensive review of the scientific literature was conducted using MEDLINE, and the relevant information was synthesized. The evidence indicates that the proprioceptive feedback that is conveyed primarily through larger type I afferents is important for postural control. However, the evidence indicates that the tactile feedback communicated through smaller type II afferents is particularly critical to the maintenance of balance. Many forms of PN often lead to chronic tactile desensitization in the soles of the feet and, although the central nervous system seems to adapt to this smaller type II afferent dysfunction by relying on more larger type I afferent reflex loops, the result is still decreased stability. We propose a model that is intended both to help explain the relationship between stability and the smaller type II afferent and the larger type I afferent feedback that may be impaired by PN and to assist in the development of pertinent rehabilitative interventions.

Biomechanics of ankle giving way:A case report of accidental ankle giving way during the drop landing test

Background:Several case studies observed that the lateral ankle sprain resulted from a sudden increase in ankle inversion accompanied by internal rotation.However,without sufficient ankle kinetics and muscle activity information in the literature,the detailed mechanism of ankle sprain is still unrevealed.The purpose of our case report is to present 2 accidental ankle giving way incidents for participants with chronic ankle instability(CAI)and compare to their normal trials with data of kinematics,kinetics,and electromyography(EMG).Case description:Two young female participants accidentally experienced the ankle giving way when landing on a 25°lateral-tilted force plate.3 D kinematics,kinetics,and muscle activity were recorded for the lower extremity.Qualitative comparisons were made between the giving way trials and normal trials for joint angles,angular velocities,moments,centers of pressure and EMG linear envelopes.Results:One participant’s giving way trial displayed increased ankle inversion and internal rotation angles in the pre-landing phase and at initial contact compared to her normal trials.Another participant’s giving way trial exhibited greater hip abduction angles and delayed activation of the peroneus longus muscle in the pre-landing phase versus her normal trials.Conclusion:A vulnerable ankle position(i.e.,more inverted and internally rotated),and a late activation of peroneus activity in the pre-landing phase could result in the ankle giving way or even sprains.A neutral ankle position and early activation of ankle evertors before landing may be helpful in preventing ankle sprains.

Cross-cultural adaptation and validation of an ankle instability questionnaire for use in Chinese-speaking population

Background:The Identification of Functional Ankle Instability(IdFAI)is a valid and reliable tool to identify chronic ankle instability;however,it was developed in English,thus limiting its usage only to those who can read and write in English.The objectives of our study were to(1)cross-culturally adapt a Chinese(Mandarin)version of the IdFAI and(2)determine the psychometric properties of the Chinese version IdFAI.Methods:The cross-cultural adaptation procedures used by the investigators and translators followed previously published guidelines and included 6 stages:(1)initial translation,(2)synthesis of the translations,(3)back translation,(4)developing the pre-final version for field testing,(5)testing the pre-final version,and(6)finalizing the Chinese version of IdFAI(IdFAI-C).Five psychometric properties of the IdFAI-C were assessed from results of 2 participant groups:bilingual(n=20)and Chinese(n=625).Results:A high degree of agreement was found between the English version of IdFAI and IdFAI-C(intra-class correlation_(2,1)=0.995).An excellent internal consistency(Cronbach'sα=0.89),test—retest reliability(intra-class correlation_(2,1)=0.970),and construct validity(r(625)=0.67)was also found for the IdFAI-C.In addition,the results of exploratory and confirmatory factor analysis indicated that ankle instability was the only construct measured from the IdFAI.Conclusion:The IdFAI-C is a highly reliable and valid self-report questionnaire that can be used to assess ankle instability.Therefore,we suggest that it can be used to effectively and accurately assess chronic ankle instability in clinical settings for Chinese-speaking individuals.

Limit Cycle Identification in Nonlinear Polynomial Systems

We present a novel formulation, based on the latest advancement in polynomial system solving via linear algebra, for identifying limit cycles in general n-dimensional autonomous nonlinear polynomial systems. The condition for the existence of an algebraic limit cycle is first set up and cast into a Macaulay matrix format whereby polynomials are regarded as coefficient vectors of monomials. This results in a system of polynomial equations whose roots are solved through the null space of another Macaulay matrix. This two-level Macaulay matrix approach relies solely on linear algebra and eigenvalue computation with robust numerical implementation. Furthermore, a state immersion technique further enlarges the scope to cover also non-polynomial (including exponential and logarithmic) limit cycles. Application examples are given to demonstrate the efficacy of the proposed framework.

Efficient scarless skin regeneration enabled by loading micronized amnion in a bioinspired adhesive wound dressing

Complete skin reconstruction is a hierarchical,physiological assembly process involving healing of the epidermis,dermis,vasculature,nerves,and cutaneous appendages.To date,few works have reported complete skin regeneration,particularly lacking vascular structures and hair follicles after full skin defects.In this study,a hydrogel derived from the skin secretion of Andrias davidianus(SSAD)that features adhesiveness was used as a bioactive scaffold to load micronized amnion(MA).The SSAD hydrogel was found to promote the migration and proliferation of amnion stem cells and human keratinocytes,as well as inhibit their apoptosis in vitro.In a rat full-skin defect model,the regeneration of skin appendages was observed at the wound area,achieving scarless healing.Transcriptome analyses further validated that SSAD could positively regulate cell migration,proliferation,and differentiation.These functions might be attributed to the abundant growth factors present in the SSAD.Synergized by the delivery of MA,SSAD loaded with the MA could achieve a significantly better skin regeneration effect than SSAD or MA used alone,providing a simple yet highly effective means to obtain complete,scarless skin regeneration,suggesting favorable potential for clinical translation.

Multi-functional vesicles improve Helicobacter pylori eradication by a comprehensive strategy based on complex pathological microenvironment

Helicobacter pylori(H.pylori),creating a global infection rate over 50%,presents great challenges in clinical therapies due to its complex pathological microenvironment in vivo.To improve the eradication efficacy,herein we fabricated a pharmaceutical vesicle RHL/Cl-Ch-cal where cholesterol-PEG,calcitriol and first-line antibiotic clarithromycin were co-loaded in the rhamnolipid-composed outer lipid layer.RHL/Cl-Ch-cal could quickly penetrate through gastric mucus layer to reach H.pylori infection sites,and then effectively destroyed the architecture of H.pylori biofilms,killed dispersed H.pylori and inhibited the re-adhesion of residual bacteria(called biofilms eradication tetralogy).Moreover,RHL/Cl-Ch-cal activated the host immune response to H.pylori by replenishing cholesterol to repair lipid raft on the cell membrane of host epithelial cells.Finally,RHL/Cl-Ch-cal killed the intracellular H.pylori through recovering the lysosomal acidification and assisting degradation.In experiments,RHL/Cl-Ch-cal demonstrated prominent anti-H.pylori efficacy in the classical H.pylori-infected mice model.Therefore,the study provides a“comprehensive attack”strategy for anti-H.pylori therapies including biofilms eradication tetralogy,immune activation and intracellular bacteria killing.

Effect of DC electric field on moisture migration characteristics in oil-pressboard

The moisture content has a great influence on the electric insulation strength of oil-pressboard.Therefore,it is very important to assess the moisture content in power transformers.There is lack of research about the effect of DC electric field on moisture migration.Here,the authors analyse the moisture migration characteristics of oil-press-board under DC electric field.The DC electric field has a greater influence on the moisture content in the oil.Compared with no DC electric field,the moisture content in oil is reduced by 22.91 mg/L at 50℃,while it is reduced by 17.63 mg/L at 70℃.Under the same moisture content in the oil,the moisture content in the pressboard which affected by the DC electric field is higher than the Oommen curve,the maximum dif-ference is 0.88%at 50℃,and 0.05%at 70℃.This result can provide a reference for the revision of existing moisture assessment methods.

Contribution of arbuscular mycorrhizal fungi and soil amendments to remediation of a heavy metal-contaminated soil using sweet sorghum

Owing to their potential advantages such as waste reduction,recycling,and economic attributes,fast-growing bioenergy crops have the capacity to effectively phytoremediate heavy metal-contaminated soils.However,little is known about the role of microbial and chemical amendments in phytoremediation using bioenergy crops.Here,we studied the contributions of inoculation with the arbuscular mycorrhizal fungus(AMF)Acaulospora mellea ZZ and three soil amendments,i.e.,hydroxyapatite(HAP),manure,and biochar,at doses of 0.1%and 1%(weight:weight)to heavy metal phytoremediation using sweet sorghum grown on an abandoned agricultural soil,with environmentally realistic contamination(2.6 mg kg^(-1) Cd,1796 mg kg^(-1) Pb,and 1603 mg kg^(-1) Zn),in a plant growth chamber.Mycorrhizal colonization,plant biomass and metal accumulation,metal availability,and soil pH were determined in harvested seedlings 12 weeks after sowing.The results showed that root colonization by indigenous AMF decreased by 28%-46%with HAP,but increased after manure and biochar applications as compared to the no amendment control(CK).The AMF inoculation increased root colonization rates by 16%^(-1)28%and in particular,alleviated the inhibition of HAP.The remediation effects were highly dependent on the amendment type and dose.Among the three soil amendments,HAP was the most effective in promoting plant growth and phytostabilization of Cd,Pb,and Zn and phytoextraction of Cd,particularly at a dose of 1%.Compared to CK,1%HAP decreased DTPA-extractable Cd,Pb,and Zn concentrations in soil by 31%-43%,30%-38%,and 22%-23%,respectively.Manure and biochar also exerted positive effects on heavy metal immobilization,as indicated by lower DTPA extractability,but only the 1%manure treatment showed plant growth-promoting effect.The AMF inoculation did not affect plant growth,but increased soil pH and induced synergistic interactions with amendments on the immobilization of Cd and Pb.In conclusion,soil amendments,particularly HAP,produced positive impacts and synergistic interactions with AMF on the phytostabilization of heavy metals using sweet sorghum.Accordingly,sweet sorghum combined with soil amendments and AMF may be an effective strategy for heavy metal phytoremediation.

Influence of moisture on the interface charge of oil-pressboard composite insulation under DC voltage

The distortion of the electric field in the oil–pressboard composite insulation caused by the accumulation of the interface charge is detrimental to both the insulation design and operation of converter transformers.The influence of moisture content on the surface charge accumulation of oil–pressboard insulation under DC voltage was studied in this study.In accordance with the Kerr electro-optic effect,the electric field strengths in transformer oil and the surface charge density were acquired after applying the positive and negative DC voltages in three oil–pressboard insulation models with different moisture content,respectively.The resistivities of the oil and pressboard in three models,namely Model 1#with 3.8–4.2 ppm moisture in oil and 0.35–0.37%moisture in pressboard,Model 2#with 7.6–7.9 ppm moisture in oil and 0.79–0.82%moisture in pressboard and Model 3#with 14.9–15.4 ppm moisture in oil and 1.39–1.42%moisture in pressboard,was also measured.The results indicate that:(i)as negative charges in oil accumulated on the pressboard surface in a much greater speed than the positive ones,the electric field in transformer oil under negative DC voltage decreases more rapidly with time than that under positive DC voltage;(ii)the increase of the moisture content in both oil and pressboard,under either positive or negative DC voltage,leads to the decrease of both the electric field strength in transformer oil and the charge density with time;and(iii)the increase of moisture content could not only decrease the resistivity of both oil and pressboard,but also the ratio of the resistivity between the pressboard and the oil.On the basis of the Maxwell–Wagner theory,the decrease of the ratio between the pressboard and oil could lead to the decrease of the interfacial charge density,leading to the slow transient process of the electric field in transformer oil under DC voltage.