A Piezoelectric-Driven Electrochromic/Electrofluorochromic Dual-Modal Display Device.

Electrochromic (EC) reflective displays offer great advantages in delivering information and providing visual data, but are limited in dark environments. Reflective/emissive dual-modal displays capable of electrochemically-induced color and fluorescence change simultaneously are highly desirable, especially possessing rapid response speed as well as long-term durability. Herein, an electroactive fluorescent ionic liquid based on triphenylamine and imidazole (EFIL-TPA) has been synthesized for reflective/emissive dual-modal display. The resultant device exhibits outstanding electrochromic/electrofluorochromic (EC/EFC) performance with low driving voltage (below 1.0 V), fast switching speed (0.57-1.8 s), and remarkable cycling durability (91% retention for 10 000 cycles). A piezoelectric nanogenerator (PENG) driven EC/EFC integrated system is fabricated to harvest energy from human motion and visually drive the color/fluorescence change for human motion indication in both bright and dark environments. This innovative EC/EFC dual-modal display device based on EFIL-TPA supports a huge space for the development of self-powered human motion visualized indication in all-light conditions.

Acceptability of male circumcision for HIV prevention among men who have sex with men in China: a short report.

Recent evidence shows that circumcision is associated with lower HIV prevalence among MSM. We assessed the acceptability of circumcision for preventing HIV and that of Shang Ring circumcision (SRC) among men who have sex with men (MSM) in China. 538 adult MSM were recruited from six cities in China between January and March 2019. Participants were surveyed by an online, self-administered questionnaire. The acceptability of circumcision was assessed before and after the potential protective effect of circumcision against HIV was informed, and subsequently men's willingness to undergo SRC was assessed. The level of circumcision was 16.4%. Of 450 uncircumcised MSM, their willingness to be circumcised in the following six months increased significantly from 32.2% to 55.6% after the information session. Three quarters of men who were willing to undergo circumcision accepted SRC. MSM who perceived that circumcision could maintain genital hygiene were more likely to accept circumcision after the information session, whereas those who regarded circumcision as an embarrassing surgery were disinclined to be circumcised. The low circumcision rate, along with its high acceptability in Chinese MSM, suggests a great potential benefit of circumcision intervention if proved effective. SRC might be a popular circumcision procedure in this population.

Awareness and uptake of non-occupational post-exposure prophylaxis (nPEP) among gay, bisexual and other men who have sex with men in China: a cross-sectional study.

Non-occupational post-exposure prophylaxis (nPEP) is recommended to reduce the likelihood of HIV infection after potential exposure. However, little is known about this practice among Chinese gay, bisexual and other men who have sex with men (GBM). GBM were enrolled from both centers for disease prevention and control (CDCs) and community health centers in six cities in China. Multivariable logistics regression was used to assess factors associated with awareness of and willingness to use nPEP. A total of 516 eligible GBM were included, 67.2% of whom were aware of nPEP, 76.0% were willing to use nPEP, and 2.3% had ever used nPEP. GBM who had college or higher education, had disclosed sexual orientation, had increased number of male sex partners in the last 6 months, and had ever tested for HIV were more likely to be aware of nPEP. Willingness to use nPEP was significantly associated with college or higher education, STI history, gay app use, and awareness of nPEP prior to study. Uptake of nPEP is still low among MSM in China. Efforts are needed to improve awareness of and access to nPEP among GBM, especially those at higher risk of HIV infection.

Rectal douching among men who have sex with men in six cities in China: a cross-sectional study.

Background Rectal douching, which is a common practice among men who have sex men (MSM) as a preparation for anal sex, may potentially increase the risk of HIV infection. However, little is known about the practice of rectal douching among Chinese MSM. This study investigated the characteristics of rectal douching and factors associated with rectal douching. METHODS: Between January and March 2019, MSM aged ≥18 years in six cities in China were recruited to the study. Participants were asked to complete a self-administered online questionnaire. Chi-squared tests and multivariable logistic regression were used to examine factors associated with rectal douching by calculating odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS: Of 485 MSM in this study, 278 (57.3%) practiced rectal douching in the preceding 6 months. The most common reasons for douching before and after anal sex were hygiene/cleanliness (78.6% and 66.1% respectively) and HIV/STI prevention (8.5% and 17.4% respectively). The most used enemas and equipment before and after anal sex were tap water (73.5% and 70.2% respectively) and showerhead hoses (76.1% and 75.2% respectively). Men who engaged in both insertive and receptive anal sex (OR 8.84; 95% CI 4.52-17.30), exclusively receptive anal sex (OR 6.56; 95% CI 3.55-12.13), condom-less anal intercourse (OR 1.64; 95% CI 1.03-2.63) and anal sex after alcohol use (OR 1.54; 95% CI 1.00-2.35) were more likely to perform douching. CONCLUSION: Rectal douching is common in MSM, some of whom may not realise the potential risks associated with douching. The co-occurrence of douching and other high-risk behaviours would make MSM more vulnerable to HIV. Health education aimed at informing MSM of the potential risks and addressing the high prevalence of douching are urgently needed.

Contextualizing the revised Patient Perception of Patient-Centeredness (PPPC-R) scale in primary healthcare settings: a validity and reliability evaluation study.

BACKGROUND: An English version of the Patient Perception of Patient-Centeredness (PPPC) scale was recently revised, and it is necessary to test this instrument in different primary care populations. AIM: This study aimed to assess the validity and reliability of a Chinese version of the PPPC scale. DESIGN: A mixed method was used in this study. The Delphi method was used to collect qualitative and quantitative data to address the content validity of the PPPC scale by calculating the Content Validity Index, Content Validity Ratio, the adjusted Kappa, and the Item Impact Score. Confirmatory factor analysis (CFA) and exploratory factor analysis (EFA) were used to assess the construct validity of the PPPC scale through a cross-sectional survey. The internal consistency was also assessed. SETTING/PARTICIPANTS: In the Delphi consultation, seven experts were consulted through a questionnaire sent by email. The cross-sectional survey interviewed 188 outpatients in Guangzhou city and 108 outpatients in Hohhot City from community health service centers or stations face-to-face. RESULTS: The 21 items in the scale were relevant to their component. The Item-level Content Validity Index for each item was higher than 0.79, and the average Scale-level content validity index was 0.97 in each evaluation round. The initial proposed 4-factor CFA model did not fit adequately. Still, we found a 3-factor solution based on our EFA model and the validation via the CFA model (model fit: [Formula: see text], P < 0.001, RMSEA = 0.044, CFI = 0.981; factor loadings: 0.553 to 0.888). Cronbach's α also indicated good internal consistency reliability: The overall Cronbach's α was 0.922, and the Cronbach's α for each factor was 0.851, 0.872, and 0.717, respectively. CONCLUSIONS: The Chinese version of the PPPC scale provides a valuable tool for evaluating patient-centered medical service quality.

Phenotypic Profiling of People With Subjective Tinnitus and Without a Clinical Hearing Loss.

Our objective was to study the characteristics of patients with subjective tinnitus and normal hearing and to investigate whether the features correlated to different shapes on audiograms. In this retrospective study, 313 patients with subjective tinnitus and clinically normal hearing were enrolled from the tinnitus outpatient department of the Eye and ENT Hospital of Fudan University. The following phenotypic variables were collected: age, dominant tinnitus pitch (TP), tinnitus loudness, tinnitus duration, tinnitus severity, sex, education, hearing thresholds, tinnitus position, and tinnitus condition. The dominant TPs of patients with normal hearing were mostly high-pitched, with a mean of 4866.8 ± 2579.6 Hz; thus, we speculated that the condition is related to high-frequency hearing threshold elevations. We further divided the patients into four subgroups based on the matched TP: (i) TP ≤ 500 Hz (n = 34), (ii) 500 Hz < TP ≤ 3,000 Hz (n = 15), (iii) 3,000 Hz < TP ≤ 8,000 Hz (n = 259), and (iv) TP > 8,000 Hz (n = 5). We studied the phenotypic profiling of different audiograms and found that the group with TP of ≤500 Hz had an average "inverted-U" shaped audiogram, and the group with TP between 500 and 3,000 Hz had a slowly ascending slope audiogram below 2,000 Hz, followed by a drastically descending slope audiogram ranging from 2,000 to 8,000 Hz; further, the high-frequency (3,000-8,000 Hz) and ultra-high-frequency (>8,000 Hz) groups had flat curves below 2,000 Hz and steeper slope audiograms over 2,000 Hz. Our findings confirmed a consistency ratio between the distributions of dominant TPs and the frequencies of maximum hearing thresholds in both ears. The dominant TP was positively correlated with the maximum hearing threshold elevation frequency (left ear: r = 0.277, p < 0.05; right ear: r = 0.367, p < 0.001). Hearing threshold elevations, especially in high frequency, might explain the appearance of dominant high-frequency TP in patients without clinically defined hearing loss. This is consistent with the causal role of high-frequency coding in the generation of tinnitus.

Normative data for rotational chair considering motion susceptibility.

Objective: Rotational Chair Test (RCT) is considered one of the most critical measures for vestibular functionality, which generally includes the sinusoidal harmonic acceleration test (SHAT), velocity step test (VST), and visual suppression (VS). The purpose of this study was to establish normal values for different age groups on the RCT and investigate whether motion susceptibility, such as with a history of motion sickness or migraine, has any effects on test metrics. Methods: One hundred and nine subjects aged from 20 to 59 years who were free from neurotological and vestibular disorders were enrolled. According to the history of motion sickness or migraine, participants were divided into four groups: the motion sickness (MS) group (n = 13), the migraine group (n = 8), comorbidity group (n = 11), and the control group (n = 77). The 77 subjects without any history of MS and migraine were then further separated into four age groups: youth group (20-29 years), young and middle-aged group (30-39 years), middle-age group (40-49 years), and middle-age and elderly group (50-59 years). All participants underwent SHAT, VST, and VS, and a comprehensive set of metrics including gain, phase, asymmetry, time constant (TC), and Fixation Index were recorded. Results: Regarding the VST and VS, no significant differences were observed either across the four groups (MS, migraine, comorbidity, and control group) or four age categories within the control group. For SHAT, VOR gain at the frequency of 0.01 Hz, VOR phase from 0.08 to 0.64 Hz, and asymmetry at 0.01, 0.16, and 0.64 Hz indicated significant differences among various age groups (P < 0.05 for all comparisons). The VOR phase lead was lower in the migraine and comorbidity group than that in the control group at 0.64 Hz (P = 0.027, P = 0.003, respectively). Conclusions: Age slightly affects the result of SHAT, but not for VST and VS. VOR gain is more susceptible to aging at low frequency, while the phase is opposite. Subjects with both migraine and motion sickness show abnormal velocity storage mechanisms. Phase bias should be considered when assessing motion susceptibility with the RCT. SHAT is more sensitive than VST in terms of reflecting motion susceptibility.

User Interface (UI) Design and User Experience Questionnaire (UEQ) Evaluation of a To-Do List Mobile Application to Support Day-To-Day Life of Older Adults.

Because of the spread of smartphones, older adults enjoy the assistance of smartphones. However, fewer mobile applications are designed for older adults. Smartphone user interface (UI) serves as an external brain to capture information, and older adults may have memory complaints that affect self-confidence and lead to memory decline. Non-declarative memory requires more effort. Therefore, this study aims to design and evaluate a to-do list application to help older adults encode, store, and retrieve non-declarative memory, such as tasks they plan to do. We recruited 15 participants (5 men and 10 women) aged 60 to 75 years old (SD = 5.32). They were asked to complete nine usability tasks, and to answer a user experience questionnaire (UEQ) and a few interview questions. Sixty percent of users completed with only one or two attempts (median = 2.80, SD = 1.63). We found three usability issues and proposed an iteration plan. The application has attractiveness, efficiency, dependability, stimulation, novelty, and good perspicuity for older adults. The product was rated excellent except for perspicuity, which met the users' expectations. This indicates that the user is satisfied with the application prototype. The results of this measurement can be utilized as a benchmark for the next model for developing mobile to-do list applications on user experience.

[Evaluation and clinical practice of vestibular function tests in acoustic neuroma].

Objective:This study was conducted to evaluate the applications of vestibular function tests in diagnosis, identifying tumor origins and prognosis of vestibular rehabilitation of patients with acoustic neuroma. Methods:This research is a single-center cross-sectional clinical study, which retrospectively analyzed the data of 335 patients with acoustic neuroma from March 2013 to March 2020 in the Eye and ENT Hospital of Fudan University. The study included caloric test, cervical and ocular vestibular evoked myogenic potentials（cVEMP, oVEMP）, video head impulse test（vHIT） and sensory organization test（SOT）. Firstly, the sensitivity, specificity, and Yoden index of each test were calculated. Secondly, the internal relevance of these tests was studied for application in judging the origins of the tumor. Results:The abnormal rates of caloric test, cVEMP, oVEMP, vHIT and SOT was 85.3%, 86.1%, 85.5%, 55.6% and 67.7% in these participants. Among all the vestibular function tests included, the caloric test showed the best sensitivity（0.855）, specificity（0.981）, and Yoden index（0.836）. The study found that the higher the Koos grades, the higher the abnormal rates of the caloric test, vHIT, and oVEMP（Cochran-Armitage test, P<0.05）. There was no significant relationship between the combination of abnormal vestibular function tests and tumor origin nerves（P>0.05）. Conclusion:Majorlty of the participants in this study with acoustic neuroma showed abnormal results in SOT related to poor balance control. More than half of the patients had at least two abnormal result of the battery of vestibular function tests, among which the caloric test was proved to have better sensitivity and specificity. The higher the Koos grades of the tumor, the higher the abnormal rates of the caloric test, vHIT, and oVEMP.

Global burden of oropharyngeal cancer attributable to human papillomavirus by anatomical subsite and geographic region.

BACKGROUND: Oropharynx is the anatomical site with the highest human papillomavirus (HPV) infection in head and neck. Many studies on HPV prevalence and p16INK4a positivity in oropharyngeal cancer have been published in recent years. We aimed to update the global burden estimates of oropharyngeal cancer attributable to HPV with the latest data and estimate global burden of tonsillar cancer and base of tongue cancer attributable to HPV by region and country. METHODS: We calculated the number of new cancer cases using the Cancer Incidence in Five Continents Volume XI (CI5XI) and country-specific population in 2012 issued by the United Nations. Estimates of HPV prevalence and p16INK4a positivity were obtained from literature search and pooled analyses where necessary. RESULTS: Globally the number of oropharyngeal cancer and tonsillar cancer attributable to HPV were 42,000 and 20,000 in 2012, corresponding to AFs of 42.7% and 52.7%. The number of cancer cases attributable to HPV among males was about 4-fold greater than that among females. For both oropharyngeal cancer and tonsillar cancer, AFs were higher in more developed countries. Among HPV positive oropharyngeal cancer cases, 86.7%, 87.8%, and 92.5% could have been prevented by bivalent (2v), quadrivalent (4v), and nonavalent (9v) HPV vaccines. CONCLUSIONS: It is worth considering the inclusion of HPV immunization in males, especially in the regions where oropharyngeal cancer is highly prevalent.

Research on the Evolutionary Game of Construction and Demolition Waste (CDW) Recycling Units' Green Behavior, Considering Remanufacturing Capability.

At present, China has not yet formed an effective development model for the industrialization of construction waste. The level of construction waste treatment and resource utilization is still low, and recycled products also lack market competitiveness. In order to promote the effective development of the remanufactured construction and demolition waste supply chain better, and based on the present situation, this manuscript establishes a game model for recycling units in two different situations: with and without remanufacturing capabilities. However, most existing studies have determined that all recycling units have remanufacturing capabilities. In the first situation, the main players of the game are recycling units with remanufacturing capabilities and consumers. In the second situation, the main players of the game are recycling units without remanufacturing capabilities and the third-party remanufacturer with remanufacturing ability. Therefore, our research can ascertain the optimal strategy choices of both parties in the game under different return situations and discuss the impact of changes to related parameters through numerical simulations. The results show: (1) When the recycling unit has remanufacturing capabilities, corporate leadership and government supervision rate have positive effects on its evolution to strict manufacturing. Only a high supervision rate can effectively suppress the negative impact of speculative gains and drive the system to (strict manufacturing; positive). Furthermore, the higher the supervision rate, the faster the system will converge. Then, the consumer's payment difference coefficient has a negative effect on the evolution of the recycling unit to strict manufacturing. The larger the payment difference coefficient, the faster the system will converge to a stable state (tendency to formal manufacturing; negative). (2) When the recycling unit does not have the ability to remanufacture, the government cost subsidy rate and the recycling unit's effort profit coefficient have positive effects on the recycling unit's evolution to the direction of effort. Meanwhile, the larger the profit coefficient of the recovery unit's effort, the faster the system will converge. The conclusions obtained provide certain theoretical guidance for the decision making of CDW recycling supply chain recovery units and relevant government departments.

Evaluation on Effectiveness of a New System as well as Analysis on Optimal Horizontal Eye Position for Vertical Video Head Impulse Test.

OBJECTIVE: To compare the performances among three different systems for video head impulse test (vHIT), and to identify an optimal target angle for precisely evaluating the function of vertical semicircular canals in vHIT. METHODS: A two-center prospective study was done. Participants were sit 1.2 m away from the wall in a noise-proved room that dedicated for vHIT experiments. During the comparison experiments, similar settings were ensured in both hospitals, with the same distance to wall and angle of staring. For each equipment, the procedures followed the developers' recommendations. The same examiner performed the comparison between two systems in one location. For the eye-position projects, targets were placed on the wall sequentially at the pre-marked lines for different angles. For the comparison projects, 9 and 13 participants were recruited, respectively. Any participant with otologic or vestibular disorders was excluded. A total of 26 healthy participants were recruited in the eye-position experiments, 16 of which were further involved in inter-examiner tests. RESULTS: Our evaluations of three different systems showed that a new vHIT system, VertiGoggles® ZT-VNG-I (VG) performed as good as the long-tested Otometrics® ICS impulse (Oto) and EyeSeeCam® (ESC). During the comparison, we validated 25-degree, instead of right ahead at 0 degree, is a better place to set the targets when torsion was applied at vertical semicircular canal planes. CONCLUSION: The new VG system is good for clinical practices. Furthermore, we proposed a new protocol to set the targets 25 degrees from right ahead after tilting head 45 degrees to evaluate vertical canals during vHIT.

Using protection motivation theory to explain the intention to initiate human papillomavirus vaccination among men who have sex with men in China.

BACKGROUND: Human papillomavirus (HPV) infection and related diseases are common among men who have sex with men (MSM). The most effective prevention is HPV vaccination. In China, however, men are not included in the HPV vaccination plan. We investigated the intention to initiate HPV vaccination and associated factors among MSM in China. Methods We surveyed 563 unvaccinated MSM aged 18 or older from six cities in China. Participants completed an electronic questionnaire about demographics, knowledge of and attitude towards HPV and HPV vaccine, intention to initiate HPV vaccination, willingness to recommend HPV vaccine to peers, feeling about government policy about HPV vaccination. We used the structural equation modeling (SEM) to analyze factors associated with HPV vaccine intention. Results The knowledge of HPV and HPV vaccine among participants was low. The mean score of knowledge about HPV and HPV vaccine was only 1.59 (range 0-11). The intention to initiate HPV vaccination within 6 months among participants was moderate (43.3% in total, 18.1% for 'very high' and 25.2% for 'above average').

Using Baidu search index to monitor and predict newly diagnosed cases of HIV/AIDS, syphilis and gonorrhea in China: estimates from a vector autoregressive (VAR) model.

OBJECTIVES: Internet search engine data have been widely used to monitor and predict infectious diseases. Existing studies have found correlations between search data and HIV/AIDS epidemics. We aimed to extend the literature through exploring the feasibility of using search data to monitor and predict the number of newly diagnosed cases of HIV/AIDS, syphilis and gonorrhoea in China. METHODS: This paper used vector autoregressive model to combine the number of newly diagnosed cases with Baidu search index to predict monthly newly diagnosed cases of HIV/AIDS, syphilis and gonorrhoea in China. The procedures included: (1) keywords selection and filtering; (2) construction of composite search index; (3) modelling with training data from January 2011 to October 2016 and calculating the prediction performance with validation data from November 2016 to October 2017. RESULTS: The analysis showed that there was a close correlation between the monthly number of newly diagnosed cases and the composite search index (the Spearman's rank correlation coefficients were 0.777 for HIV/AIDS, 0.590 for syphilis and 0.633 for gonorrhoea, p<0.05 for all). The R2 were all more than 85% and the mean absolute percentage errors were less than 11%, showing the good fitting effect and prediction performance of vector autoregressive model in this field. CONCLUSIONS: Our study indicated the potential feasibility of using Baidu search data to monitor and predict the number of newly diagnosed cases of HIV/AIDS, syphilis and gonorrhoea in China.

Spectroscopic studies on the interactions between imidazolium chloride ionic liquids and bovine serum albumin.

The binding of three imidazolium chloride ionic liquids (ILs) with bovine serum albumin (BSA) were investigated by UV absorption spectra, fluorescence spectra and synchronous fluorescence spectra. The results showed that the UV absorption of the BSA was red-shift, and intensity of UV absorption declined with the increase in concentration of ILs. According to fluorescence spectra, fluorescence quenching of the BSA was happened with ILs added, and the main reason is static quenching. The study of synchronous fluorescence spectra indicated that ILs interacted with tryptophan (Trp) and tyrosine (Tyr) residues, changed the structure and the internal hydrophobic conformation of BSA. The binding constant K and the numbers of binding sites n were obtained by Stern-Volmer equation. For [Bmim]Cl, K=16.12 L mol(-1), n was 0.64; for [Hmim]Cl, K=31.48 L mol(-1), n was 0.70; for [Omim]Cl, K=355.22 L mol(-1), n was 0.99. The binding strength of ILs with BSA is expected to show the trend with the length of carbon chain, [Bmim]Cl<[Hmim]Cl<[Omim]Cl.

[Mechanism and kinetics of phenol degradation by TiO2 photocatalytic combined technologies].

The combination H2O2, or electrical catalytic (EC) system with TiO2 photbcatalytic system for phenol degradation was investigated. The catalytic systems of TiO2/UV, H2O2/UV, TiO2/UV/H2O2 and TiO2/UV/EC were compared to investigate the phenol degradation mechanism and kinetic model. The degradation of phenol in TiO2/UV/H2O2 and TiO2/UV/EC system is more effective than that in TiO2/UV system. With the solution pH of 6, TiO, concentration of 0.2 g.L-1, UV illumination of 2 h, the photocatalysis removal efficiency of phenol reaches to 86%, if the current density of 12 mA.cm-2 is added, the removal efficiency of phenol could reach to 100%. The energy utilization in different catalytic systems was also compared. When phenol is degraded in 15 min, in TiO2/UV/EC system the energy utilization is the highest of 0.0306 g.(kW. h)-1 with the energy consumption of 0.0640 kW.h-1. It indicates that much more energy is used in TiO2/UV/EC system for phenol degradation. During the analysis of intermediate products in different catalysis systems, the first-order kinetic model of phenol degradation and intermediate products such as hydroquinone, catechol and benzoquinone formation were established. The kinetic model is validated the phenol degradation pathway in different catalysis systems, and also indicates the TiO2/UV/EC system could enhance phenol and intermediate products degradation.

[Effects of imidazolium chloride ionic liquids on the acute toxicity and weight of earthworm].

Standard contact filter paper test of OECD and artificial soil test were used to study the acute lethal effect of three imidazolium chloride ionic liquids, 1-butyl- 3-methylimidazolium chloride ([Bmim] Cl), 1-hexyl- 3-methylimidazolium chloride ([Hmim] Cl), and 1-octyl- 3-methylimidazolium chloride ([Omim] Cl) on earthworm (Eisenia fetida), and the weight of the earthworms was measured after subtle exposure. The 24 h-LC50 values of [Bmim] Cl, [Hmim] Cl and [Omim] Cl using the contact filter paper method were 109.60, 50.38 and 7.94 microg x cm(-2), respectively. The 48 h-LC50 values were 98.52, 39.14 and 3.61 microg x cm(-2), respectively. Using the artificial soil method, the 7 d-LC50 values of [Bmim] Cl, [Hmim] Cl and [Omim] Cl were 447.78, 245.56 and 180.51 mg x kg(-1), respectively, and the 14 d-LC50 values were 288.42, 179.75, 150.35 mg x kg(-1), respectively. There were differences in poisoning symptoms of the three ionic liquids on earthworms. The growth of Eisenia fetida was inhibited and declined with increasing ionic liquid concentration. The toxicity of ionic liquids on Eisenia fetida increased with the length of carbon chain.

Enantioselective phytotoxicity of metolachlor against maize and rice roots.

Rac-metolachlor, a widely used chloracetanilide herbicide, is now being replaced by S-metolachlor in many countries. The enantioselective effects of rac- and S-metolachlor on root growth of maize and rice was studied in hydroponics. Visible morphological changes in root growth were observed after treatment with rac- or S-metolachlor. The main root and lateral roots were shorter in length, and the number of lateral roots was reduced. The half inhibition (IC(50,5d)) values for root length of rac- and S-metolachlor were 18.86 and 10.61 µM, respectively, for maize, and 7.33 and 5.35 µM, respectively, for rice. The root system activity after treatment with rac- or S-metolachlor was lower than that of the control, while the root membrane permeability was higher. The activities of superoxide dismutase, peroxidase, and catalase in the roots were lower after rac- or S-metolachlor treatment compared to those of the control, while the malondialdehyde content was higher. After rice was treated with 3.1 µM rac- or S-metolachlor, the cell wall separated from the cell membrane, and some destruction of nuclei and organelles was observed. The entire cell was destroyed after treatment with 12.4 µM rac- or S-metolachlor. The results showed that S-metolachlor has stronger effects than rac-metolachlor on crop roots.