Body Shape Research Articles

Dietary diversity and its association with changes in anthropometric indices of community-dwelling older adults in Tehran, Iran: a longitudinal study (2017–2021)

BackgroundDietary diversity refers to the consumption of a variety of foods or food groups over a given reference period, which is crucial for improving nutrition and overall health. This longitudinal study aimed to investigate the association between dietary diversity and anthropometric indices in community-dwelling older adults living in Tehran in 2017 and 2021.MethodsThe current study was conducted on 368 older adults [204 (55.4%) women and 164 (44.6%) men] over 60 years of age living in Tehran, who were selected by a systematic cluster sampling method at two-time points, 2017 and 2021. Anthropometric measures (weight, height, hip circumference, and waist circumference) were assessed with standard methods. The participants’ dietary intake was assessed by completing two non-consecutive 24-hour recalls, and dietary diversity score (DDS) was calculated based on Kant’s method. Statistical analysis was performed using R software by the mixed effect model method.ResultsThe mean DDS of the participants in 2017 (5.07 ± 1.20) was higher than that in 2021 (4.94 ± 1.09) (p < 0.05). DDS and dairy diversity score decreased significantly over time. After adjusting for confounders, there was an inverse relationship between the DDS and Body Mass Index (BMI) (B = -0.22; SE = 0.09), but the interaction effect of year × DDS (B = 0.19; SE = 0.10) was not significant (p = 0.06). However, there was a positive relationship between the DDS and A Body Shape Index (ABSI) (B = 0.00; p = 0.022), after adjusting for confounders, this relationship was no longer significant. Additionally, the interaction effect of year and DDS on the ABSI was not significant.ConclusionThe dietary intake and dietary diversity of older adult residents of Tehran declined dramatically with age, and a higher DDS was associated with improved anthropometric indices. DDS had an inverse relationship with general obesity in the studied participants, and the passage of time did not affect this relationship. The DDS can be used as a predictive index and is a powerful tool for investigating changes in nutritional status in longitudinal studies of old age. However, longer-duration studies are needed to obtain more conclusive results.

Virtual skeleton and body mass for revealing the life strategies of Sinosaurus

ABSTRACT Sinosaurus from the Lufeng Basin, Yunnan Province, is the largest and most famous predatory dinosaur from the Early Jurassic in China. Although a number of specimens have been discovered in the past, no studies to date have focused exclusively on complete skeletal articulation, estimation of mass, or life strategies. Based on surface scans of a new well-preserved specimen, a digital skeleton of Sinosaurus was produced in two poses: osteologically neutral pose and extended pose. We estimated the possible living body mass by three volumetric-density methods, advocating the use of the expanding convex hulls method of 849.6 kg with the COM (0.41, 1.31, 0.00) as a more reliable result, which is greater than the mass of traditional regression formulas. The body shape and skull/body length suggested that Sinosaurus was a great runner, and this, combined with the weak crests and large forelimbs, further led to the conclusion that both the head and forelimbs were required to prey. This finding is also consistent with the finding that Sinosaurus has a moderate ability to metabolise body heat in the skin, as reflected by the surface/volume ratio.

Shaping the skeleton: impact of GnRH analogue and sex hormone therapy on skeletal dimensions in transgender individuals.

Skeletal dimensions vary between sexes. Men typically have broader shoulders and women a wider pelvis. If gender affirming hormone therapy (GAHT) with or without prior puberty suppression (PS) alters these dimensions in transgender individuals remains unclear. To investigate impact of PS and GAHT on skeletal dimensions. Retrospective cross-sectional study. Gender identity clinic. Transgender individuals assigned male at birth (AMAB) and assigned female at birth (AFAB) who underwent dual-energy X-ray absorptiometry (DXA) scanning between ages 18 and 28 years were divided into four groups: Early PS (Tanner G/B2-3)+GAHT, Late PS (Tanner G/B4-5)+GAHT, GAHT only, and Untreated. Shoulder and pelvis dimensions measured by DXA scan were compared between groups, with adjustment for height. A total of 121 individuals AMAB and 122 AFAB were included. Only in individuals AMAB who underwent early PS had smaller shoulders compared to untreated individuals AMAB (-1.3 cm; 95%CI -2.1; -0.5). In individuals AMAB from both the early and late PS group, pelvic inlet, pubic symphysis width and interischial distance were greater compared to untreated individuals AMAB resulting in dimensions comparable to untreated individuals AFAB. Only in early PS AFAB pelvic inlet width was smaller compared to untreated individuals AFAB (-1.0 cm; 95%CI -1.5; -0.6), and comparable to untreated individuals AMAB. The study results suggest that skeletal dimensions are only altered by GAHT if endogenous puberty has not yet been completed at start of PS. These findings enhance our understanding of hormonal effects on the skeleton and may hold clinical relevance for body image as well as for forensic anthropology. Future research should evaluate clinical implications for surgical or obstetrical outcomes in transgender individuals.

Association between body shape index and coronary heart disease in individuals over 20 years old with obese

BackgroundWhile body mass index (BMI) defines obesity as a well-established risk factor for cardiovascular disease, the paradoxical theory of BMI suggests that obesity may indeed have a favorable impact on the prognosis of cardiovascular disease. Therefore, this study aims to assess the correlation between body shape index (ABSI), which is a novel measure of obesity, and coronary heart disease (CHD) among obese individuals in the United States.MethodsThe data from the National Health and Nutrition Examination Survey (NHANES) were evaluated by us for 5046 patients. We assessed the exposure variable ABSI, which includes waist circumference (WC), height, and BMI. The outcome variable was CHD.ResultsThe cross-sectional study included a total of 5046 obese adults aged over 20 years, with an average age (standard deviation: SD) of 49.86 (16.24) years and a male proportion of 44.57%.The odds ratio (OR) values for CHD in Model 1, Model 2, 3 were found to be 2.45 (95%CI: 2.12, 2.83), 1.53 (95%CI:1.30, 1.81) and 1.31 (95%CI:1.09, 1.56) per SD increase in ABSI, respectively. In the fully adjusted model, we designated participants in the T1 group as the reference group. Our findings indicate a significant increase in the prevalence of CHD (OR:1.82, 95%CI: 1.07–3.10) only within the T3 group. Although there is an increased prevalence of CHD (OR:1.32, 95%CI: 0.77–2.29) in the T2 group, no statistically significant difference was observed.ConclusionsThe increase in ABSI is strongly associated with the rise in CHD prevalence among obese individuals in the United States.

Association of body shape phenotypes and body fat distribution indexes with inflammatory biomarkers in the European Prospective Investigation into Cancer and Nutrition (EPIC) and UK Biobank

BackgroundThe allometric body shape index (ABSI) and hip index (HI), as well as multi-trait body shape phenotypes, have not yet been compared in their associations with inflammatory markers. The aim of this study was to examine the relationship between novel and traditional anthropometric indexes with inflammation using data from the European Prospective Investigation into Cancer and Nutrition (EPIC) and UK Biobank cohorts.MethodsParticipants from EPIC (n = 17,943, 69.1% women) and UK Biobank (n = 426,223, 53.2% women) with data on anthropometric indexes and C-reactive protein (CRP) were included in this cross-sectional analysis. A subset of women in EPIC also had at least one measurement for interleukins, tumour necrosis factor alpha, interferon gamma, leptin, and adiponectin. Four distinct body shape phenotypes were derived by a principal component (PC) analysis on height, weight, body mass index (BMI), waist (WC) and hip circumferences (HC), and waist-to-hip ratio (WHR). PC1 described overall adiposity, PC2 tall with low WHR, PC3 tall and centrally obese, and PC4 high BMI and weight with low WC and HC, suggesting an athletic phenotype. ABSI, HI, waist-to-height ratio and waist-to-hip index (WHI) were also calculated. Linear regression models were carried out separately in EPIC and UK Biobank stratified by sex and adjusted for age, smoking status, education, and physical activity. Results were additionally combined in a random-effects meta-analysis.ResultsTraditional anthropometric indexes, particularly BMI, WC, and weight were positively associated with CRP levels, in men and women. Body shape phenotypes also showed distinct associations with CRP. Specifically, PC2 showed inverse associations with CRP in EPIC and UK Biobank in both sexes, similarly to height. PC3 was inversely associated with CRP among women, whereas positive associations were observed among men.ConclusionsSpecific indexes of body size and body fat distribution showed differential associations with inflammation in adults. Notably, our results suggest that in women, height may mitigate the impact of a higher WC and HC on inflammation. This suggests that subtypes of adiposity exhibit substantial variation in their inflammatory potential, which may have implications for inflammation-related chronic diseases.

The Morphological and Molecular Characterization of the Avian Trematodes Harrahium obscurum and Morishitium dollfusi (Digenea: Cyclocoelidae) from the Middle Volga Region (European Russia).

The taxonomic status of many species of the family Cyclocoelidae is still unclear. Two species of cyclocoelids, Harrahium obscurum and Morishitium dollfusi, were collected from the air sacs of birds (Turdus merula and Tringa ochropus) inhabiting the Middle Volga region (European Russia). Here, we provide the first detailed morphological description of these cyclocoelids and combine it with the first molecular phylogenetic analysis of Cyclocoelidae from birds in Russia based on partial sequences of their 28s rDNA and coI mtDNA genes. Specimens of both flatworm species from different host individuals differ slightly in body shape and size, which probably reflects host-induced intraspecific variability. For the first time, we have shown that a stable morphological character such as the length of the vitelline fields in the studied digeneans is variable at the species level and cannot be used in their morphological diagnosis.

Temporal changes in the body shape of the Pacific thread herring Opisthonema libertate on the Western Baja California Sur coast

Temporal changes in the body shape of the Pacific thread herring Opisthonema libertate on the Western Baja California Sur coast

Citra Perempuan dalam Memoar Imperfect karya Meira Anastasia

This study was created with the aims to describe: First, to describe the physical image of women in the memoir Imperfect by Meira Anastasia. Second, the psychological image of women in the memoir Imperfect by Meira Anastasia. Third, the image of women in their relationship with family in the memoir Imperfect by Meira Anastasia, and fourth, the image of women in their relationship with society in the memoir Imperfect by Meira Anastasia. This type of research is literary research using a mimetic approach. The data source in this research is the memoir Imperfect by Meira Anastasia. Data collection techniques in this research were carried out by reading, marking events and taking inventory of the data found. The results of this research are. First, the physical image of women which consists of a pot belly, fat body and breast shape. Second, the psychological image of women in the form of a sense of self-acceptance towards things around them, love and existence in the environment. Third, social image in relation to the family consisting of mother, wife, children and younger siblings. And fourth, the social image of women in their relationship with society, such as friendship, between people, their relationship with men, and as society's idol.

The association between abdominal obesity and depressive symptoms among Chinese adults: Evidence from national and regional communities

BackgroundThe association between body shape and depressive symptoms has been reported in adults. The present study aimed to investigate the association between body shape-specific abdominal obesity and depressive symptoms among multi-regional Asian adults. MethodsThe 2011–2012 China Health and Retirement Longitudinal Study and 2022–2023 Hangzhou study were used as the discovery and validation datasets, respectively. Body shape was assessed by body mass index categories. Abdominal obesity was defined as a body shape index (ABSI) ≥ 75th centile. Depression was measured using 10-item Centre for Epidemiological Studies Depression Scale and Geriatric Depression Scale short 15-item version, respectively. General linear and multinomial logistic models were used to explore the association of ABSI, abdominal obesity with depressive scores and presence, respectively. ResultsA total of 12,229 and 1210 participants were included in the discovery and validation datasets, respectively. A non-linear reverse L-shaped association was found between ABSI and depressive scores. Participants with abdominal obesity had higher depressive scores (β = 0.05, 95%CI = 0.01–0.09; and β = 0.13, 95%CI = 0.01–0.24; respectively). Stratified analyses showed that abdominal obesity was associated with higher depressive scores (β = 0.09, 95%CI = 0.00–0.17; and β = 0.25, 95%CI = 0.05–0.46; respectively) and presence (OR = 1.46, 95%CI = 1.02–2.10; and OR = 3.95, 95%CI = 1.58–9.84; respectively) in overweight adults. Furthermore, abdominal obesity was associated with depressive symptoms among overweight females, but not among males. LimitationCausal links weren't addressed because of the observational study design. ConclusionAbdominal obesity exhibited a positive association with depressive symptoms among Asian overweight adults, particularly in females. Prevention and early diagnosis of depressive symptoms should focus on overweight females.

Individualized generation of women's prototype based on the classification of body shape

The traditional prototype method only relies on the basic dimensions of the human body such as bust girth and back length to make the prototype pattern, ignoring the differences of human body details dimensions. In order to improve the fit of garments, the research on intelligent generation technology of individualized garment patterns has become one of the hot spots in the field of clothing. Based on the 3D body scanning technology, we proposed a method for generating prototype pattern based on body shape classification. The proposed method takes as inputs the body parameters (width, thickness and angle), while the output of the method is one of the four pattern generation rules-"Y" shape, "V" shape, "I" shape, or "X" shape. 207 subjects were divided into four categories based on the body angle parameters, namely "Y" shape, "V" shape, "I" shape and "X" shape, and a shape recognition model was built. The pattern database is required to obtain pattern generation rules by 3D point cloud reconstruction and flattening. Combined with the human body shape parameters, the mathematical formulas of the feature points on the pattern landmarks are built. The accuracy of body shape recognition model is 97.4%. The error analysis of the predicted pattern parameters shows that 90% of the pattern feature points have a goodness of fit above 0.7. In the 5 main landmarks, the proportion of pattern within the absolute error range is more than 80%, indicating that the prediction effect of the pattern is good. This method can be applied to the process of automatic pattern generation system based 2D measurement to improve work efficiency.

Comparison of novel and traditional anthropometric indices in Eastern-China adults: which is the best indicator of the metabolically obese normal weight phenotype?

BackgroundPeople with the metabolically obese normal weight (MONW) phenotype have been confirmed to significantly increase the risk of unfavorable health consequences. This study aimed to investigate the relationships between traditional and novel anthropometric indices with the MONW phenotype and compare the predictive ability of different anthropometric indices in identifying individuals with the MONW phenotype.MethodsThis cross-sectional study involved a total of 26,332 participants aged 18 years or older with a normal weight from Nanjing, China. Sociodemographic information, biochemical measurements, and anthropometric indices were collected. The novel body fat anthropometric indices included body shape index (ABSI), body roundness index (BRI), abdominal volume index (AVI), weight-adjusted-waist index (WWI), body adiposity index (BAI), conicity index (CI), waist-hip-height ratio (WHHR), as well as traditional indices such as waist circumference (WC), hip circumference (HC), body mass index (BMI), waist-to-hip ratio (WHR), and waist-to-height ratio (WHtR).The prevalence ratio (PR) from modified poisson regression and area under the receiver-operating characteristic curve (AUC) were conducted to compare the association and predictive capacity of different obesity indicators for the MONW phenotype. All analyses were stratified by sex.ResultsModified poisson regression analyses revealed that weight, WC, HC, BMI, WHR, WHtR, ABSI, BRI, AVI, WWI, BAI, CI, and WHHR were independently associated with higher risk of the MONW phenotype, regardless of whether they were treated as a continuous or categorical variable (P < 0.05). Notably, BRI demonstrated the strongest association in both men (highest quartile VS lowest quartile; PR = 3.14, 95%CI, 2.49, 3.96; P < 0.001) and women (PR = 4.63, 95%CI, 3.81, 5.62; P < 0.001). Receiver operating characteristic analysis indicated that AUC for the different anthropometric indices ranged from 0.50 to 0.80. BRI and WHtR had the largest AUC in both males (both AUC = 0.733; 95% CI, 0.717, 0.750) and females (both AUC = 0.773; 95% CI, 0.761, 0.786). The optimal cut-off points for BRI, determined by maximizing the Youden’s index, were 3.102 (sensitivity: 63.2%, specificity: 36.2%) in males and 3.136 (sensitivity: 68.9%, specificity: 44.2%) in females. Moreover, BRI and WHtR exhibited the highest diagnostic accuracy in younger age groups, specifically those aged 18–34 in both sexes.ConclusionsBRI emerged as the optimal predictor and independent determinant of the MONW phenotype, regardless of gender. This association was particularly pronounced in young individuals.

Investigating the structure of disordered eating symptoms in adult men: A network analysis.

Eating disorders (EDs) increasingly emerge as a health risk in men, but there is concern that men's symptoms go unnoticed due to stereotypical perceptions and gender-related differences in symptom presentation. Novel assessments focused particularly on attitudes and behaviours towards increasing muscle size and definition. Using network analysis, this study aimed to corroborate and extend previous findings on disordered eating presentation in men by examining the role of muscularity concerns among an extended range of disordered eating symptoms. N=294 adult men (18years or older) completed muscularity-related and disordered eating assessments, among which we included assessments for orthorexic eating and Avoidant/Restrictive Food Intake Disorder for the first time. We selected symptoms empirically, estimated a regularised network, identified symptom communities, evaluated network loadings and bridge centrality estimates, and compared network structures between different groups of participants. We identified five symptom communities related to muscularity-related concerns, features of core ED psychopathology, and selective eating. Symptoms regarding ruminating about healthy eating, guilt for unhealthy eating, weight overvaluation, concerns about muscularity, and selective eating emerged as highly central. The results largely corroborate previous observations but suggest that muscle-building behaviours are part of a broader cluster of male body shaping and rule-based dieting behaviours.

Gambaran Self-Esteem Siswa SMA dan Implikasinya dalam Pelayanan Konseling

This study is motivated by students who cannot express their opinions, cannot accept their strengths and weaknesses and have difficulty interacting with friends and the irenvironment, feel inferior to their body shape, different skin color compared to their friends and during class hours students do not dare to express their opinions in front of the class because they are not confident. This study aims to describe the description of self-esteem at SMAN 1 2X11 Enam Lingkung. This type of research is quantitative with a descriptive approach. The population of this study was 694 students at SMAN 1 2X11 Enam Lingkung in the 2024/2025 school year and a sample of 328 students taken through proportional random sampling technique. Data collection in this study used a Likert scale, namely a self-esteem questionnaire that has been tested for validity with the Pearson correlation formula (0.355). The data in this study were processed with descriptive statistical analysis techniques. The results of this study indicate that the self-esteem of students at SMAN 1 2X11 Enam Lingkung as a wholeis in themoderate category (65.24). Based on the results of this study, counseling teachers can provide assistance to improve students' self-esteem in the form of information services, content mastery services and group guidance services.

Hubungan Body Image dengan Self Esteem pada Siswa SMA dan Implikasinya dalam Pelayanan Konseling

This research is motivated by students who have low self-esteem because students feel they have a negative body image. Students tend to be dissatisfied with their body shape, and even consider physical condition to be a mandatory standard that other people pay attention to. This research aims to describe body image and self-esteem in students and their implications for counseling services. This type of research uses a quantitative approach with descriptive methods. The population of this study was 694 students of SMAN 1 2x11 Enam Lingkung who were registered in the 2024/2025 academic year, the sample for this study was 328. Sample selection used proportional random sampling technique. The data collection technique uses a scale for body image and self-esteem. Data were analyzed using descriptive techniques. The research results show that overall body image is in the medium category, while overall self-esteem is in the high category. Services that can be provided to students to improve body image and self-esteem include information services and group guidance services.

Bisecting the type series of Leporinus paranensis Garavello and Britski, 1987 (Characiformes, Anostomidae)

The type series of Leporinus paranensis includes two distinct species, one of which is herein described as new. Leporinus paranensis is redescribed based on its holotype, two paratypes, and additional specimens recently sampled in tributaries of the Grande river, in the north portion of the upper Paraná basin in Brazil. A new species of Leporinus is described based on specimens collected in all major tributaries of the upper Paraná basin in Brazil, and tributaries of the Paraná river in Paraguay. Both species share the presence of three unicuspid teeth on the premaxillary and four on dentary, terminal mouth and three dark midlateral blotches on the body. The new species is distinguished from L. paranensis based on the number of scale series around the caudal peduncle (12 vs. 16). The variation in the body shape of both species were compared through a Principal Component Analysis and showed that they share a similar body shape. Species delimitation analyses using DNA Barcode were applied to compare samples of the new species to congeners and corroborated the uniqueness of the new species. In addition, molecular data revealed that L. bahiensis, L. octofasciatus, and L. taeniatus are possibly closely related to the new species. The conservation status of L. paranensis and the new species are discussed using the IUCN criteria.

GAMBARAN PERCEIVED SOCIAL SUPPORT PADA IBU POSTPARTUM PRIMIPARA YANG MEMILIKI BODY IMAGE POSITIF

Perceived social support (PSS) received by postpartum primiparous mothers are considered effective to support the whole forming process regarding body image satisfaction after giving birth. This research was aimed to get an overview of PSS in primiparous postpartum mothers with body image satisfaction using descriptive qualitative research methods involving three participants. The data collection process was carried out by using semi-structured interviews and analyzed using the thematic analysis method. The research results show that there are differences between how which PSS plays an important role in helping mothers perceived post partum’s body shape changes. Out of the four types of PSS, emotional/esteem support and belonging/companionship support are considered to play an important role in helping the process of forming a body image satisfaction for primiparous postpartum mothers. How they perceive the social support they received supports them in accepting, increasing self-confidence, and understanding their body shape after giving birth.

The effect of cinnamon supplementation on eating disorder indices among people suffering from binge eating disorder: a randomized controlled trial

BackgroundBinge eating disorder is one of the main eating disorders that is characterized by recurrent binge eating episodes that lead to complications like high blood pressure, diabetes, dyslipidemia, etc. Many psychological and biological factors can lead to binge eating disorder and one of the main physiological reasons is insulin resistance. Cinnamon is an old favorite that has positive effects on insulin sensitivity. So, we examined the effect of cinnamon on binge eating disorder in this study.MethodsThis study was conducted on 40 binge eating disorder patients with a BMI between 25 and 39.9 kg/m2. They were divided into two groups one of them consumed 6 g of cinnamon per day while the other group consumed 6 g of white wheat as a placebo. Before and after the study we examined weight, height, Body Shape Questionnaire (BSQ), and Binge Eating Scale (BES) scale in all participants and did the statistical analysis.ResultsThere were no significant differences in baseline characteristics, gender, height, weight, BMI, education, and marriage status between the two groups. There were no significant changes between BSQ, BES, weight, and height after the study either.ConclusionAccording to our findings, although the weight of the patients in the cinnamon group decreased significantly, after the end of the study, no significant difference was observed in the weight, BMI, and BAS and BSQ indices between the two groups.Trial registrationThe study protocol was registered in the Iran Registry of Clinical Trials (IRCT) center (IRCT code: IRCT20090822002365N26, Registration date: 2021/11/7).

The estimation of different body dimensions of children aged 6-11 years for the needs of furniture designers.

There are some rules that furniture designers must take into consideration to design ergonomic furniture. The main design principle is the target group for which the furniture will be designed, considering the dimensions of people who use the furniture. The paper presents the correlation between 12 parts of children's body, as well as the proportion between stature and 11 other parts of the body which are used for the purposes of furniture and interior designers. Field measurements include: Stature (S), Sitting height (She), Shoulder height (Sh), Popliteal height (Ph), Hip width (Hb), Elbow rest height (Erh), Buttock-popliteal length (Bpl), Buttock-knee length (Bkl), Thigh clearance (Tc), Eye height sitting (Eh), Knee height (Kh) and Shoulder breadth (Sb) to pupils aged 6-11 (grades 1 to 5). The measurements were done in 687 children in 12 primary schools in 4 different regions in Kosovo. The data of the study shows that, in general, there is a correlation (in some parts strong and in some medium) for the measured parts. Also, the study presents the proportion between the stature and other parts of the body which are necessary for the design of children's furniture. Using this data will enable furniture designers to easily target the dimensions of the group they will design, even by measuring only one dimension, i.e. stature and then setting the proportions for each piece separately.

Mechanical and instability analysis of asphalt overlay during construction on cement concrete pavement with a large longitudinal slope

ABSTRACT There are insufficient stability problems in overlay construction on tourist highways in mountainous and island areas, especially the pavement with a large longitudinal slope. To elaborate on the instability characteristics of overlay, the construction stage of overlay is divided into loose state, paving stage and initial compaction stage. The moulding methods of specimens during the paving and initial compaction stages were determined. The evolution law of contact-slip characteristics and shear strength of overlay was analysed. The mechanical models of the construction stability of the composite pavements were constructed, instability characterisation methods were proposed and instability characteristics of asphalt overlay during construction were discussed. The results show that the paving state of overlay can be simulated by changing the rolling frequency and the compaction number. There is a risk of slip instability of loose overlay and the longitudinal gradient should be less than 12% to reduce this risk. The critical instability equivalent area ratio and critical slip area proposed can quantitatively describe the shape of the instability body and the instability critical condition. The longitudinal gradient significantly affects the interlaminar instability, but the internal instability mainly depends on the shear strength of asphalt overlay.

Simultaneous tracking of ultrafast surface and gas-phase dynamics in solid-gas interfacial reactions.

Real-time detection of intermediate species and final products at the surface and near-surface in interfacial solid-gas reactions is critical for an accurate understanding of heterogeneous reaction mechanisms. In this article, an experimental method that can simultaneously monitor the ultrafast dynamics at the surface and above the surface in photoinduced heterogeneous reactions is presented. This method relies on a combination of mass spectrometry and femtosecond pump-probe spectroscopy. As a model system, the photoinduced reaction of methyl iodide on and above a cerium oxide surface is investigated. The species that are simultaneously detected from the surface and gas-phase present distinct features in the mass spectra, such as a sharp peak followed by an adjacent broad shoulder. The sharp peak is attributed to the species detected from the surface, while the broad shoulder is due to the detection of gas-phase species above the surface, as confirmed by multiple experiments. By monitoring the evolution of the sharp peak and broad shoulder as a function of the pump-probe time delay, transient signals are obtained that describe the ultrafast photoinduced reaction dynamics of methyl iodide on the surface and in the gas-phase. Finally, SimION simulations are performed to confirm the origin of the ions produced on the surface and in the gas-phase.