1.Compact Fundus Imaging System Using Shack-Hartmann Wavefront Sensing for High-speed Auto-focus
Zhe-Kai LIN ; Long CHEN ; Geng-Yong ZHENG ; Jin-Tian HUANG ; Jia-Xin DONG ; Shang-Pan YANG ; Wen-Zheng DING ; Ding-An HAN ; Xue-Hua WANG ; Ya-Guang ZENG
Progress in Biochemistry and Biophysics 2026;53(4):1076-1086
ObjectiveThe widespread adoption of portable fundus cameras for primary care and community screening is hindered by limitations in current autofocus(AF) technologies. Image-based methods relying on sharpness evaluation require iterative searches, resulting in slow convergence, while projection-based techniques are susceptible to optical artifacts and calibration errors. To address these challenges, this study introduces a novel AF system based on direct wavefront sensing, designed to deliver simultaneous high speed, high precision, and operational robustness within the compact form factor essential for portable ophthalmic devices. MethodsOur approach fundamentally reimagines the AF process by directly measuring the ocular wavefront aberration. We developed a custom portable fundus camera integrating a miniaturized Shack-Hartmann wavefront sensor (SHWS) into the optical path. An 850 nm laser diode projects a point source onto the retina via oblique illumination to minimize corneal reflections. Light scattered from this spot carries the eye’s refractive error through the imaging optics and is directed to the SHWS, positioned at a plane optically conjugate to the primary color CMOS imaging sensor. A microlens array within the SHWS samples the incident wavefront, generating a pattern of focal spots on a CCD. Real-time centroid analysis of these spots provides a map of local wavefront slopes. These measurements are processed through a singular value decomposition (SVD) algorithm to fit a Zernike polynomial basis set, enabling real-time reconstruction of the wavefront phase. The defocus component (S) is extracted from the second-order Zernike coefficients, providing a direct, quantitative measure of the refractive error in diopters. This value serves as a precise error signal in a closed-loop control system, which commands a voice-coil actuated focusing lens to its null position in a single, deterministic step, eliminating the need for iterative search algorithms. ResultsComprehensive evaluation demonstrated the system’s high performance. Testing on a calibrated model eye (OEMI-7) established a highly linear relationship between the computed defocus S and the focusing lens position across a ±20 Diopter (D) compensation range, achievable within a 5 mm mechanical travel. The system achieved a focusing precision of 0.08 D, corresponding to an 18-fold improvement over a conventional projection spot-size method tested under identical conditions. The total focus acquisition time, encompassing wavefront measurement, computation, and lens actuation, averaged under 0.5 s. Clinical validation with 25 human volunteers (50 eyes, refractive range -15 D to +10 D) confirmed practical efficacy. The wavefront-sensing AF succeeded in 92% of attempts with a mean time of 0.5 s, substantially outperforming a projection-based benchmark which achieved only a 32% success rate with an average time of 4.25 s. The system provided instantaneous directional guidance and maintained stability during minor ocular movements. Objective assessment of image quality, via amplitude contrast of retinal vasculature, showed consistent and significant enhancement following AF correction across the entire tested diopter range. ConclusionThis work successfully implements and validates a direct wavefront-sensing autofocus paradigm for portable fundus cameras. By directly quantifying and compensating for the optical defocus aberration, this method bypasses the fundamental limitations of image-processing and projection-based techniques, enabling rapid, precise, and deterministic diopter compensation. The developed system delivers an exceptional combination of a wide operational range (±20 D), high accuracy (0.08 D), fast convergence (0.5 s), and a compact physical footprint. This technology provides a practical and high-performance focusing solution capable of enhancing the reliability, throughput, and diagnostic utility of portable retinal imaging in large-scale screening applications. Future efforts will be directed towards system cost optimization and performance adaptation for diverse ocular conditions.
2.A Systematic Strategy for Discovering First-in-class Anti-fibrotic Drugs from Traditional Chinese Medicine
Wen HUANG ; Guang XIN ; Sanyin ZHANG ; Tao WANG ; Wei CHEN ; Zeliang WEI ; Qilong ZHOU ; Ke LI ; Dan SUN ; Kui YU ; Shilin CHEN
Chinese Journal of Experimental Traditional Medical Formulae 2026;32(10):296-307
Pulmonary fibrosis(PF) is a progressive and life-threatening disease with limited therapeutic options, highlighting the urgent need for innovative drug discovery strategies. To address this challenge, the authors propose the formula-originated rational intelligent screening&translation(FIRST), a systematic framework for developing anti-fibrotic monomers derived from classical traditional Chinese medicine(TCM). The strategy integrates three key dimensions, including tissue-oriented intelligent screening of active compounds, structural optimization based on drug-target spatial interactions and plant biosynthetic pathways, and cross-scale validation of drug. We further highlight its applications in discovering tissue-oriented novel drugs from clinically validated TCM, the development and mechanistic elucidation of anti-fibrotic therapeutics, as well as the clinical translation and secondary development of candidate drugs. This strategy paves the way for first-in-class, formula-derived monomeric drugs with defined structures, clarified mechanisms, and proven safety, offering a transformative avenue to meet the urgent therapeutic needs of PF and setting a new paradigm for TCM-based drug innovation.
3.A Systematic Strategy for Discovering First-in-class Anti-fibrotic Drugs from Traditional Chinese Medicine
Wen HUANG ; Guang XIN ; Sanyin ZHANG ; Tao WANG ; Wei CHEN ; Zeliang WEI ; Qilong ZHOU ; Ke LI ; Dan SUN ; Kui YU ; Shilin CHEN
Chinese Journal of Experimental Traditional Medical Formulae 2026;32(10):296-307
Pulmonary fibrosis(PF) is a progressive and life-threatening disease with limited therapeutic options, highlighting the urgent need for innovative drug discovery strategies. To address this challenge, the authors propose the formula-originated rational intelligent screening&translation(FIRST), a systematic framework for developing anti-fibrotic monomers derived from classical traditional Chinese medicine(TCM). The strategy integrates three key dimensions, including tissue-oriented intelligent screening of active compounds, structural optimization based on drug-target spatial interactions and plant biosynthetic pathways, and cross-scale validation of drug. We further highlight its applications in discovering tissue-oriented novel drugs from clinically validated TCM, the development and mechanistic elucidation of anti-fibrotic therapeutics, as well as the clinical translation and secondary development of candidate drugs. This strategy paves the way for first-in-class, formula-derived monomeric drugs with defined structures, clarified mechanisms, and proven safety, offering a transformative avenue to meet the urgent therapeutic needs of PF and setting a new paradigm for TCM-based drug innovation.
4.Correlation between arterial stiffness and incident chronic kidney disease among old adults taking health check-up
Guang YANG ; Xin SHEN ; Bokai CHENG ; Jiebin HOU ; Yabin ZHANG ; Hongyu CHEN ; Qingli CHENG ; Yansong ZHENG ; Jiahui ZHAO
Chinese Journal of Geriatric Heart Brain and Vessel Diseases 2025;27(9):1173-1178
Objective To investigate the correlation between arterial stiffness(AS)and incident chronic kidney disease(CKD)among the elderly individuals taking health checkup.Methods A retrospective study was conducted on 857 elderly individuals without CKD at baseline who taking physical exams in our medical center from December 2009 to May 2021.Their clinical and labora-tory data were collected.Brachial-ankle pulse wave velocity(baPWV)was used to assess the se-verity of AS,and then the subjects were divided into normal elasticity group(201 cases),and moderate(490 cases)and severe AS group(166 cases).Kaplan-Meier curves were plotted to dis-play cumulative incidence rates of incident CKD across different AS groups.Restricted cubic splines(RCS)and Cox regression models were applied to analyze the correlation of baPWV and incident CKD risk.Results The severe AS group had significantly advanced age,greater ratio of hypertension,larger waist circumference,higher HR,SBP and DBP,increased urinary albumin/creatinine ratio(UACR),elevated levels of TG and fasting blood glucose,and baPWV than the normal elasticity group(P<0.05).During the follow-up period,37 participants developed CKD.The incidence of CKD was obviously higher in the severe AS group than the normal arterial elas-ticity group(9.04%vs 3.48%).RCS analysis revealed a U-shaped relationship between baPWV and incident CKD risk.When baPWV ≥1 400 cm/s,each standard deviation increase in baPWV indicates the risk of incident CKD increasing by 71%(HR=1.71,95%CI:1.30-2.25,P<0.01).Regardless of adjustment for covariates or not,baPWV remained positive correlation with inci-dent CKD risk(P<0.05).Conclusion Among the elderly individuals undergoing health check-up,increased AS severity is significantly associated with higher risk of incident CKD when baP-WV ≥1400 cm/s.
5.Guideline for Adult Weight Management in China
Weiqing WANG ; Qin WAN ; Jianhua MA ; Guang WANG ; Yufan WANG ; Guixia WANG ; Yongquan SHI ; Tingjun YE ; Xiaoguang SHI ; Jian KUANG ; Bo FENG ; Xiuyan FENG ; Guang NING ; Yiming MU ; Hongyu KUANG ; Xiaoping XING ; Chunli PIAO ; Xingbo CHENG ; Zhifeng CHENG ; Yufang BI ; Yan BI ; Wenshan LYU ; Dalong ZHU ; Cuiyan ZHU ; Wei ZHU ; Fei HUA ; Fei XIANG ; Shuang YAN ; Zilin SUN ; Yadong SUN ; Liqin SUN ; Luying SUN ; Li YAN ; Yanbing LI ; Hong LI ; Shu LI ; Ling LI ; Yiming LI ; Chenzhong LI ; Hua YANG ; Jinkui YANG ; Ling YANG ; Ying YANG ; Tao YANG ; Xiao YANG ; Xinhua XIAO ; Dan WU ; Jinsong KUANG ; Lanjie HE ; Wei GU ; Jie SHEN ; Yongfeng SONG ; Qiao ZHANG ; Hong ZHANG ; Yuwei ZHANG ; Junqing ZHANG ; Xianfeng ZHANG ; Miao ZHANG ; Yifei ZHANG ; Yingli LU ; Hong CHEN ; Li CHEN ; Bing CHEN ; Shihong CHEN ; Guiyan CHEN ; Haibing CHEN ; Lei CHEN ; Yanyan CHEN ; Genben CHEN ; Yikun ZHOU ; Xianghai ZHOU ; Qiang ZHOU ; Jiaqiang ZHOU ; Hongting ZHENG ; Zhongyan SHAN ; Jiajun ZHAO ; Dong ZHAO ; Ji HU ; Jiang HU ; Xinguo HOU ; Bimin SHI ; Tianpei HONG ; Mingxia YUAN ; Weibo XIA ; Xuejiang GU ; Yong XU ; Shuguang PANG ; Tianshu GAO ; Zuhua GAO ; Xiaohui GUO ; Hongyi CAO ; Mingfeng CAO ; Xiaopei CAO ; Jing MA ; Bin LU ; Zhen LIANG ; Jun LIANG ; Min LONG ; Yongde PENG ; Jin LU ; Hongyun LU ; Yan LU ; Chunping ZENG ; Binhong WEN ; Xueyong LOU ; Qingbo GUAN ; Lin LIAO ; Xin LIAO ; Ping XIONG ; Yaoming XUE
Chinese Journal of Endocrinology and Metabolism 2025;41(11):891-907
Body weight abnormalities, including overweight, obesity, and underweight, have become a dual public health challenge in Chinese adults: overweight and obesity lead to a variety of chronic complications, while underweight increases the risks of malnutrition, sarcopenia, and organ dysfunction. To systematically address these issues, multidisciplinary experts in endocrinology, sports science, nutrition, and psychiatry from various regions have held multiple weight management seminars. Based on the latest epidemiological data and clinical evidence, they expanded the guideline to include assessment and intervention strategies for underweight, in addition to the core content of obesity management. This guideline outlines the etiological mechanisms, evaluation methods, and multidimensional management strategies for overweight and obesity, covering key areas such as diagnosis and assessment, medical nutrition therapy, exercise prescription, pharmacological intervention, and psychological support. It is intended to provide a scientific and standardized approach to weight management across the adult population, aiming to curb the rising prevalence of obesity, mitigate complications associated with abnormal body weight, and improve nutritional status and overall quality of life.
6.Epidemic factors in foodborne parasitic diseases in ethnic minority areas of Guizhou Province from a One Health perspective
Li-dan LU ; Mu-xin CHEN ; Shan CAI ; Dan-ya SHE ; Guang-chu LIN ; Song-ping LI ; Kai-neng MO ; Cheng ZHOU ; Ling LI
Chinese Journal of Zoonoses 2025;41(5):480-486
This study was aimed at understanding the prevalence and influencing factors of food-borne parasitic diseases in ethnic minority areas of Guizhou Province,to provide a scientific basis for the development of appropriate intervention measures based on the human-animal-environment One Health concept.In 2023,the infection status of the human population,reservoir hosts,intermediate hosts,food-borne parasitic diseases,and related social and environmental factors were investigated in Congjiang County in Qidongnan Miao and Dong Autonomous Prefecture;Luodian County in Qiannan Buyi and Miao Autonomous Prefecture;and Ceheng County in Qianxinan Buyi and Miao Autonomous Prefecture.At least 1 000 individuals were sampled from each county,along with at least 50 insect-protected host samples from each location.Food-borne parasite infections were detected with the modified Kato thick smear method.A questionnaire survey was administered to the population.Detection of food-borne parasitic metacercariae was performed in intermediate host fish through the flaking and digestion method,and in crabs through the pounding and sedimentation method.The chi-square test was used to compare rates,and logistic regression was applied for multivariate analysis.A total of 3 023 questionnaires and fecal samples were collected.Males accounted for 47.50%,females accounted for 52.50%,and members of ethnic minorities accounted for 96.06%.A total of 186 food-borne parasitic infections were identified,and the infection rate was 6.15%.Five insect species were detected,which showed an infection rate of 5.39%.The infection rate of Clonorchis sinensis was 0.33%,that of Taenia was 0.40%,that of Heteroceles was 0.17%,that of Acanthus was 0.17%,and that of Echinostoma was 0.03%.Human infections with Echinostomus colloides and Echinostomia transferoris had not previously been reported in China.Single-factor analysis revealed statistically significant differences in food-borne parasite infections according to various factors,including the consumption of untreated water,raw fish and shrimp,raw pig blood,raw cow gastric juice,and raw pork and beef,as well as raw pig and cow viscera(P<0.05).Multivariate analysis indicated that the risk factors for food-borne parasite infections among residents in minority areas of Guizhou Province included the consumption of raw pig blood(OR=2.841,95%CI:1.809-4.463),raw cow gastric juice(OR=2.122,95%CI:1.297-3.469),and raw fish and shrimp(OR=1.779,95%CI:1.049-3.018).A total of 173 fecal samples of the reservoir host were examined,which showed a rate of food-borne parasite infection of 5.2%.A total of 510 intermediate host fish were examined,which showed a 4.51%positivity rate of encysted metacercaria of Clonorchis sinensis.The crab,pig,and beef samples were not positive.In conclusion,food-borne parasitic infections were prevalent in ethnic minority regions of Guizhou Province,and consumption of raw food were influencing factors.A focus on populations with raw food consumption habits,including raw pig blood,cow gastric juice,fish and shrimp,is essential.Concurrently,monitoring of animal hosts must be strengthened to perform key interventions according to the One Health concept.
7.Efficacy and safety of a facilitated percutaneous coronary intervention with half-dose recombinant staphylokinase in ST-segment elevation myocardial infarction
Tian-yu WU ; Wen-hao ZHANG ; Peng-sheng CHEN ; Chen LI ; Tian WU ; Zhan LÜ ; Tong WANG ; Kun LIU ; Zhi-wen TAO ; Xiao-xuan GONG ; Liang YUAN ; Yong LI ; Bo CHEN ; Xin CHEN ; Zeng-guang CHEN ; Nai-quan YANG ; Yuan-yuan SANG ; Xiao-yan WANG ; Bai-hong LI ; Li ZHU ; Guo-yu WANG ; Xin ZHAO ; Chuan LU ; Jun JIANG ; Rui-na HAO ; Chun-jian LI
Chinese Journal of Interventional Cardiology 2025;33(8):431-438
Objective To investigate the clinical efficacy and safety of facilitated percutaneous coronary intervention(PCI)with half-dose recombinant staphylokinase(r-SAK)in patients with ST-segment elevation myocardial infarction(STEMI)who are expected to undergo PCI within 120 minutes.Methods From October 2021 to August 2022,a total of 200 STEMI patients in eight centers were included and randomly assigned in a 1﹕1 ratio to either r-SAK group or control group.Patients received loading doses of aspirin and ticagrelor and intravenous heparin and were randomized to receive an intravenous bolus of either 5 mg r-SAK or normal saline prior to PCI.The outcomes were set as ST-segment resolution(STR)at 60-90 minutes after PCI,the proportion and transition of pathological Q waves on the 5th day after PCI,and the proportion of high-sensitivity cardiac troponin T(hs-cTnT)peaking within 12 hours of onset.The safety outcome was major bleeding events defined as Bleeding Academic Research Consortium(BARC)≥type 3 bleeding during hospitalization.Results Compared with the control group,the r-SAK group had a higher proportion of STR≥70%within 60-90 minutes after PCI(58.3%vs.40.3%,P=0.009);a lower proportion of pathological Q waves(59.1%vs.74.1%,P=0.040);a lower rate of Q wave progression(14.8%vs.43.2%,P<0.001);a higher rate of Q wave disappearance(12.5%vs.3.7%,P=0.027);and a higher proportion of hs-cTnT peaking within 12 hours of symptom onset[31/40(77.5%)vs.17/33(51.5%),P=0.027].Regarding the safety outcome,no significant difference in BARC≥type 3 bleeding was found between the two groups during hospitalization(P>0.05).Conclusions For STEMI patients who were expected to undergo primary PCI within 120 minutes of symptom onset,the facilitated PCI with half-dose r-SAK significantly increased the proportion of STR≥70%at 60-90 minutes after PCI,reduced the formation of pathological Q waves,and shortened the time to peak hs-cTnT,without increasing the risk of bleeding,which should be an alternative reperfusion strategy worthy of further study.
8.Recommendation for Forensic Identification Guidelines on Insulin Overdoes
Yu-Hao YUAN ; Zhong-Hao YU ; Jia-Xin ZHANG ; Long-Da MA ; Shu-Quan ZHAO ; Ning-Guo LIU ; Rong-Qi WU ; Biao ZHANG ; Xin-Biao LIAO ; Xin CHEN ; Guang-Long HE ; Yi-Wu ZHOU
Journal of Forensic Medicine 2025;41(2):168-175
Insulin is an important protein hormone that participates in multiple metabolic pathways.Biosynthetic insulin has been widely used in the treatment of type 1 and type 2 diabetes.Currently,the number of reported cases of insulin overdose both at home and abroad is gradually increasing,and insulin homicide is no longer a means of"committing murder without leaving a trace".At present,there are no systematic protocols for the identification of insulin overdose in the field of forensic medi-cine in China.This article introduces the causes,toxicological characteristics,forensic examination,labo-ratory testing methods and indicator reference of insulin overdose.Based on the identification practice and research results and referring to relevant studies on insulin overdose at home and abroad,this pa-per aims to provide recommendations and references for the formulation of forensic identification guide-lines for insulin overdose cases.
9.Correlation between arterial stiffness and incident chronic kidney disease among old adults taking health check-up
Guang YANG ; Xin SHEN ; Bokai CHENG ; Jiebin HOU ; Yabin ZHANG ; Hongyu CHEN ; Qingli CHENG ; Yansong ZHENG ; Jiahui ZHAO
Chinese Journal of Geriatric Heart Brain and Vessel Diseases 2025;27(9):1173-1178
Objective To investigate the correlation between arterial stiffness(AS)and incident chronic kidney disease(CKD)among the elderly individuals taking health checkup.Methods A retrospective study was conducted on 857 elderly individuals without CKD at baseline who taking physical exams in our medical center from December 2009 to May 2021.Their clinical and labora-tory data were collected.Brachial-ankle pulse wave velocity(baPWV)was used to assess the se-verity of AS,and then the subjects were divided into normal elasticity group(201 cases),and moderate(490 cases)and severe AS group(166 cases).Kaplan-Meier curves were plotted to dis-play cumulative incidence rates of incident CKD across different AS groups.Restricted cubic splines(RCS)and Cox regression models were applied to analyze the correlation of baPWV and incident CKD risk.Results The severe AS group had significantly advanced age,greater ratio of hypertension,larger waist circumference,higher HR,SBP and DBP,increased urinary albumin/creatinine ratio(UACR),elevated levels of TG and fasting blood glucose,and baPWV than the normal elasticity group(P<0.05).During the follow-up period,37 participants developed CKD.The incidence of CKD was obviously higher in the severe AS group than the normal arterial elas-ticity group(9.04%vs 3.48%).RCS analysis revealed a U-shaped relationship between baPWV and incident CKD risk.When baPWV ≥1 400 cm/s,each standard deviation increase in baPWV indicates the risk of incident CKD increasing by 71%(HR=1.71,95%CI:1.30-2.25,P<0.01).Regardless of adjustment for covariates or not,baPWV remained positive correlation with inci-dent CKD risk(P<0.05).Conclusion Among the elderly individuals undergoing health check-up,increased AS severity is significantly associated with higher risk of incident CKD when baP-WV ≥1400 cm/s.
10.Guideline for Adult Weight Management in China
Weiqing WANG ; Qin WAN ; Jianhua MA ; Guang WANG ; Yufan WANG ; Guixia WANG ; Yongquan SHI ; Tingjun YE ; Xiaoguang SHI ; Jian KUANG ; Bo FENG ; Xiuyan FENG ; Guang NING ; Yiming MU ; Hongyu KUANG ; Xiaoping XING ; Chunli PIAO ; Xingbo CHENG ; Zhifeng CHENG ; Yufang BI ; Yan BI ; Wenshan LYU ; Dalong ZHU ; Cuiyan ZHU ; Wei ZHU ; Fei HUA ; Fei XIANG ; Shuang YAN ; Zilin SUN ; Yadong SUN ; Liqin SUN ; Luying SUN ; Li YAN ; Yanbing LI ; Hong LI ; Shu LI ; Ling LI ; Yiming LI ; Chenzhong LI ; Hua YANG ; Jinkui YANG ; Ling YANG ; Ying YANG ; Tao YANG ; Xiao YANG ; Xinhua XIAO ; Dan WU ; Jinsong KUANG ; Lanjie HE ; Wei GU ; Jie SHEN ; Yongfeng SONG ; Qiao ZHANG ; Hong ZHANG ; Yuwei ZHANG ; Junqing ZHANG ; Xianfeng ZHANG ; Miao ZHANG ; Yifei ZHANG ; Yingli LU ; Hong CHEN ; Li CHEN ; Bing CHEN ; Shihong CHEN ; Guiyan CHEN ; Haibing CHEN ; Lei CHEN ; Yanyan CHEN ; Genben CHEN ; Yikun ZHOU ; Xianghai ZHOU ; Qiang ZHOU ; Jiaqiang ZHOU ; Hongting ZHENG ; Zhongyan SHAN ; Jiajun ZHAO ; Dong ZHAO ; Ji HU ; Jiang HU ; Xinguo HOU ; Bimin SHI ; Tianpei HONG ; Mingxia YUAN ; Weibo XIA ; Xuejiang GU ; Yong XU ; Shuguang PANG ; Tianshu GAO ; Zuhua GAO ; Xiaohui GUO ; Hongyi CAO ; Mingfeng CAO ; Xiaopei CAO ; Jing MA ; Bin LU ; Zhen LIANG ; Jun LIANG ; Min LONG ; Yongde PENG ; Jin LU ; Hongyun LU ; Yan LU ; Chunping ZENG ; Binhong WEN ; Xueyong LOU ; Qingbo GUAN ; Lin LIAO ; Xin LIAO ; Ping XIONG ; Yaoming XUE
Chinese Journal of Endocrinology and Metabolism 2025;41(11):891-907
Body weight abnormalities, including overweight, obesity, and underweight, have become a dual public health challenge in Chinese adults: overweight and obesity lead to a variety of chronic complications, while underweight increases the risks of malnutrition, sarcopenia, and organ dysfunction. To systematically address these issues, multidisciplinary experts in endocrinology, sports science, nutrition, and psychiatry from various regions have held multiple weight management seminars. Based on the latest epidemiological data and clinical evidence, they expanded the guideline to include assessment and intervention strategies for underweight, in addition to the core content of obesity management. This guideline outlines the etiological mechanisms, evaluation methods, and multidimensional management strategies for overweight and obesity, covering key areas such as diagnosis and assessment, medical nutrition therapy, exercise prescription, pharmacological intervention, and psychological support. It is intended to provide a scientific and standardized approach to weight management across the adult population, aiming to curb the rising prevalence of obesity, mitigate complications associated with abnormal body weight, and improve nutritional status and overall quality of life.

Result Analysis
Print
Save
E-mail