Dexmedetomidine for analgesia and sedation in newborn infants receiving mechanical ventilation.

BACKGROUND: Dexmedetomidine is a selective alpha-2 agonist with minimal impact on the haemodynamic profile. It is thought to be safer than morphine or stronger opioids, which are drugs currently used for analgesia and sedation in newborn infants. Dexmedetomidine is increasingly being used in children and infants despite not being licenced for analgesia in this group. OBJECTIVES: To determine the overall effectiveness and safety of dexmedetomidine for sedation and analgesia in newborn infants receiving mechanical ventilation compared with other non-opioids, opioids, or placebo. SEARCH METHODS: We searched CENTRAL, MEDLINE, Embase, CINAHL, and two trial registries in September 2023. SELECTION CRITERIA: We planned to include randomised controlled trials (RCTs) and quasi-RCTs evaluating the effectiveness of dexmedetomidine compared with other non-opioids, opioids, or placebo for sedation and analgesia in neonates (aged under four weeks) requiring mechanical ventilation. DATA COLLECTION AND ANALYSIS: We used standard Cochrane methods. Our primary outcomes were level of sedation and level of analgesia. Our secondary outcomes included days on mechanical ventilation, number of infants requiring additional medication for sedation or analgesia (or both), hypotension, neonatal mortality, and neurodevelopmental outcomes. We planned to use GRADE to assess the certainty of evidence for each outcome. MAIN RESULTS: We identified no eligible studies for inclusion. We identified four ongoing studies, two of which appear to be eligible for inclusion; they will compare dexmedetomidine with fentanyl in newborn infants requiring surgery. We listed the other two studies as awaiting classification pending assessment of full reports. One study will compare dexmedetomidine with morphine in asphyxiated newborns undergoing hypothermia, and the other (mixed population, age up to three years) will evaluate dexmedetomidine versus ketamine plus dexmedetomidine for echocardiography. The planned sample size of the four studies ranges from 40 to 200 neonates. Data from these studies may provide some evidence for dexmedetomidine efficacy and safety. AUTHORS' CONCLUSIONS: Despite the increasing use of dexmedetomidine, there is insufficient evidence supporting its routine use for analgesia and sedation in newborn infants on mechanical ventilation. Furthermore, data on dexmedetomidine safety are scarce, and there are no data available on its long-term effects. Future studies should address the efficacy, safety, and long-term effects of dexmedetomidine as a single drug therapy for sedation and analgesia in newborn infants.

Healthcare experience of adults with COPD during the COVID-19 pandemic: a rapid review of international literature.

BACKGROUND: People living with chronic obstructive pulmonary disease (COPD) are a group who may be particularly vulnerable to COVID-19. This vulnerability has been associated with increased anxiety or fear about exposure to the virus, which may also impact upon experience in healthcare settings. AIM/OBJECTIVES: The aim of this narrative mixed-methods review was to systematically scope, identify and synthesise findings from peer-reviewed qualitative, quantitative and mixed-methods studies published in academic journals describing the healthcare experiences of adults living with COPD independently in the community, following the emergence of COVID-19 in December 2019-June 2022. METHODS: Databases including Ovid MEDLINE, PsychINFO, Ovid Emcare and CINAHL Plus were searched. Studies were uploaded to Covidence to support selection and appraisal of studies. Studies were appraised for quality using the Mixed Methods Appraisal Tool. A narrative synthesis of these themes was provided, and qualitative and quantitative findings are interpreted together in the discussion. FINDINGS: The quality and experience of care for patients with COPD was impacted through the COVID-19 pandemic. Innovations and adoption of technologies such as telehealth and telerehabilitation were well received and mitigated the potential implications of severe disruption to care access to some extent. Patients feared feeling forgotten and experienced isolation and anxiety; however, telerehabilitation and exercise through modalities such as Zoom classes help support social connection and physical activity. IMPLICATIONS: These innovations are likely to be useful to be offered to patients on an ongoing basis, and education and standardised protocols around their use will benefit healthcare providers and patients alike. PROSPERO REGISTRATION NUMBER: CRD42022341168.

The Associations Between Preoperative Anthropometry and Postoperative Outcomes in Infants Undergoing Congenital Heart Surgery.

Aim: We explored the association between preoperative anthropometry and biochemistry, and postoperative outcomes in infants with CHD after cardiac surgery, as infants with congenital heart disease (CHD) often have feeding difficulties and malnutrition. Methodology: This was a retrospective review of infants (≤ 1-year-old) who underwent congenital heart surgery. Preoperative anthropometryin terms of preoperative weight-for-age z-score (WAZ), length-for-age z-score (LAZ), as well as preoperative serum albumin and hemoglobin concentrations, were evaluated against 6-month mortality, and morbidity outcomes including postoperative complications, vasoactive inotrope score, duration of mechanical ventilation, length of stay in the pediatric intensive care unit and in hospital, using the logistic regression or median regression models accounting for infant-level clustering. Results: One hundred and ninety-nine operations were performed in 167 infants. Mean gestational age at birth was 38.0 (SD 2.2) weeks (range 26 to 41 weeks). Thirty (18.0%) infants were born preterm (<37 weeks). The commonest acyanotic and cyanotic lesions were ventricular septal defect (26.3%, 44/167), and tetralogy of Fallot (13.8%, 23/167), respectively. Mean age at cardiac surgery was 94 (SD 95) days. Feeding difficulties, including increased work of breathing during feeding, diaphoresis, choking or coughing during feeding, and inability to complete feeds, was present in 54.3% (108/199) of infants prior to surgery, of which 21.6% (43/199) required tube feeding. The mean preoperative WAZ was-1.31 (SD 1.79). Logistic regression models showed that low preoperative WAZ was associated with increased risk of postoperative complications (odds ratio 1.82; p = 0.02), and 6-month mortality (odds ratio 2.38; p = 0.008) following CHD surgery. There was no meaningful association between the other preoperative variables and other outcomes. Conclusion: More than 50% of infants with CHD undergoing cardiac surgery within the first year of life have feeding difficulties, of which 22% require to be tube-fed. Low preoperative WAZ is associated with increased postoperative complications and 6-month mortality.

Association of central obesity and high body mass index with function and cognition in older adults.

OBJECTIVE: To investigate the association of normal BMI with central obesity (CO), high BMI with CO, high BMI without CO, and normal BMI without CO, with function and cognition in older adults. METHODS: Cross-sectional study involving 754 participants ≥ 65 years. Data collected include demographics, cognition, and physical measurements. RESULTS: Females had a higher prevalence of high BMI with CO and a lower prevalence of high BMI without CO than males (61.0% vs 44.6% and 4.6% vs 15.0%, respectively). Within gender, CO groups, regardless of BMI, had lower mini-mental state examination (MMSE), handgrip strength (HGS), and longer timed-up-and-go (TUG) scores. Overall, the high BMI without CO group had the highest MMSE scores, HGS, and shortest TUG. Amongst males, HGS was significantly lower in the normal BMI with CO group (B -3.28, 95% CI -6.32 to -0.23, P = 0.04). CO, regardless of normal/high BMI, had significantly longer TUG time (B 2.65, 95% CI 0.45 to 4.84, P = 0.02; B 1.07, 95% CI 0.25 to 1.88, P = 0.01, respectively) than normal BMI without CO group. CO was associated with lower MMSE scores in both genders but significant only in males with normal BMI and CO (B -1.60, 95% CI -3.15 to -0.06, P = 0.04). CONCLUSION: CO may be a better predictor of obesity and adverse outcomes in older adults. High BMI without CO was associated with better outcomes especially in males but require further validation. Prospective longitudinal studies are needed to ascertain the impact of BMI and/or CO on function, cognition, mortality, and gender differences.

Possible Sarcopenia and Impact of Dual-Task Exercise on Gait Speed, Handgrip Strength, Falls, and Perceived Health.

Background: Sarcopenia is defined as a progressive age-related loss in muscle mass and strength affecting physical performance. It is associated with many negative outcomes including falls, disability, cognitive decline, and mortality. Protein enriched diet and resistance training have shown to improve muscle strength and function but there is limited evidence on impact of dual-task exercise in possible sarcopenia. Objective: To evaluate impact of community-based dual-task exercise on muscle strength and physical function in possible sarcopenia defined by either slow gait (SG) or poor handgrip strength (HGS). The secondary aims include effect on cognition, frailty, falls, social isolation, and perceived health. Methods: Community-dwelling older adults ≥60 years old were recruited from screening program intended to identify seniors at risk, and invited to participate in dual-task exercise program called HAPPY (Healthy Aging Promotion Program for You). One hundred and eleven participants with possible sarcopenia completed 3 months follow-up. Questionnaire was administered on demographics, frailty, sarcopenia, falls, perceived health, social network, functional, and cognitive status. Physical performance included assessment of HGS, gait speed, and Short Physical Performance Battery test (SPPB). Results: The mean age of the Exercise group was 75.9 years old and 73.0% were women. The Exercise group had more female (73.0 vs. 47.5%), were older (75.9 vs. 72.5 years old), had higher prevalence of falls (32.4 vs. 15.0%), lower BMI (23.7 vs. 25.8), and education (4.0 vs. 7.2 years). The gait speed of the Exercise group increased significantly with significant reduction in the prevalence of SG and poor HGS. All components of SPPB as well as the total score increased significantly while the prevalence of pre-frailty and falls dropped by half. The risk of social isolation reduced by 25% with significant improvement in perceived health and cognition in the Exercise group. Significant impact on improvement gait speed and SPPB persisted after adjustment for baseline factors. Conclusion: Dual-task exercise program is effective in improving gait speed, SPPB score, and reducing the prevalence of poor HGS with significant improvement in perceived health, cognition, and reduction in falls and frailty. Future prospective randomized control trials are needed to evaluate the effectiveness of dual-task interventions in reversing sarcopenia.

Motoric cognitive risk syndrome, physio-cognitive decline syndrome, cognitive frailty and reversibility with dual-task exercise.

INTRODUCTION: Cognitive frailty (CF) is associated with dementia and disability. It was initially proposed in 2013 by the International Institute of Nutrition and Aging and the International Geriatrics Association. Over the years, there have been many emerging definitions e.g., Motoric Cognitive Risk Syndrome (MCR), Physio-cognitive Decline Syndrome (PCDS), reversible CF and potentially reversible CF. OBJECTIVE: Our objective was to determine the demographics including physical, functional, and psychosocial factors for the four CF definitions amongst community-dwelling older adults. In addition, the effect of dual-task exercise on the reversibility of different definitions of CF was also studied. METHODS: Participants were community-dwelling older adults aged ≥60 years recruited between August 2017 and December 2019. Older adults screened to be frail, prefrail or have cognitive impairment were invited to participate in dual-task exercise program called HAPPY (Healthy Ageing Promotion Program for You). Improvement in cognition, frailty, and physical performance after a 3-month dual-task exercise intervention program was compared with controls. RESULTS: The prevalence of CF depending on definition ranged from 8.8% to 28.7% with minimal overlap. The cognitive scores were significantly lower in all the groups predominantly affecting non-memory domains except for reversible CF. Frailty was three to seven times more prevalent in CF. MCR group had higher prevalence of functional limitation, pain and depression. All four groups had significant increase in global cognition scores especially in the attention domain where the control group declined, and reduction in the prevalence of frailty post intervention. MCR and reversible CF were significantly associated with increased odds of cognitive improvement after 3 months of intervention compared with control. CONCLUSION: CF is a novel concept and regardless of the definitions, is a target for reversing frailty, functional limitation and cognitive impairment through dual-task exercise. Long-term prospective studies are needed to evaluate the effectiveness of dual-task interventions in delaying the conversion to dementia and reduction of disability.

Prevalence of sarcopenia in pre-frail community dwelling older adult and utility of SARC-F, SARC-CalF and calf circumference in case finding.

OBJECTIVE: To determine the prevalence of sarcopenia in the pre-frail community dwelling older adults based on the Asian Workgroup for Sarcopenia (AWGS 2019) criteria. In addition, the utility of case finding using the SARC-F, SARC-CalF and calf circumference on impact of prevalence was explored. METHODS: 75 older adults ≥65 years old were recruited between October 2019 and March 2020. The algorithms of AWGS 2019 was applied retrospectively to pre-frail participants recruited for an intervention study in primary care setting. In addition to demographics, SARC-F, calf circumference (CC), muscle mass, grip strength, gait speed, 5-time chair stand timing and short physical performance battery test (SPPB) were measured, to determine sarcopenia using AWGS 2019. SARC-CalF was determined using SARC-F and CC. RESULTS: The prevalence of sarcopenia based on AWGS 2019 algorithm was 16.0%, possible sarcopenia 73.3% and severe sarcopenia 12.0%. Using SARC-F for case finding reduced the overall prevalence of sarcopenia to 4.0%, possible sarcopenia to 12.0% and severe sarcopenia to 4.0%. Positive percentage agreement of case finding criteria of SARC-F, SARC-CaIF and calf circumference for sarcopenia was 33%, 42% and 58% respectively. CONCLUSIONS: Using the AWGS 2019 without case finding, the prevalence of sarcopenia was 16%. However, using SARC-F for case finding underestimated prevalence in this group by 75%. Utility of SARC-F for case finding in pre-frail requires further evaluation.

Relationship Between Fear of Falling, Fear-Related Activity Restriction, Frailty, and Sarcopenia.

OBJECTIVES: To determine the prevalence of fear of falling (FOF) and fear-related activity restriction (FAR) and their association with frailty, sarcopenia, gait speed and grip strength, cognitive impairment, depression, social isolation, self-perceived health, and vision. DESIGN: Observational cross-sectional study. SETTING: Community. PARTICIPANTS: A total of 493 community-dwelling older adults, 60 years and older. MEASURES: FOF and FAR were assessed using validated single closed-ended questions. Questionnaire was administered to evaluate frailty (FRAIL scale - Fatigue, Resistance, Aerobic, Illness, and Loss of Weight), sarcopenia (SARC-F - lifting and carrying 10 pounds, walking across a room, transferring from bed/chair, climbing a flight of 10 stairs, and frequency of falls in the past 1 year), social isolation (six-item Lubben Social Network Scale), depression (Even Briefer Assessment Scale), cognition (Chinese Mini-Mental State Examination), and perceived general health and pain (The EuroQol-5 Dimension (EQ-5D)and EQ visual analogue scale (EQ VAS)) . Binary logistic regression was performed to determine the influence of sociodemographic, medical, functional, and cognitive variables on FOF with/without FAR. RESULTS: Prevalence of FOF was 69.2%, and among them, 38.4% had FAR. Prevalence of FOF with or without FAR in those with sarcopenia was 93.3% and in prefrail/frail was 76.6%. FOF was significantly associated with prefrail/frail (odds ratio (OR) = 2.17; 95% confidence interval (CI) = 1.26-3.73), depression (OR = 4.90; 95% CI = 1.06-22.67), number of medications (OR = 1.28; 95% CI = 1.03-1.59), and female sex (OR = 3.54; 95% CI = 1.82-6.90). FOF + FAR was associated with depression (OR = 5.17; 95% CI = 1.84-14.54) and sarcopenia (OR = 8.13; 95% CI = 1.52-43.41). CONCLUSION: FOF with/without FAR is highly prevalent among community-dwelling older adults, especially in those with sarcopenia, prefrailty, and frailty, with significant negative impact on function, quality of life, social network, and mental health. Further research is needed to investigate the value of population-level screening, causal relationship, and efficacy of comprehensive intervention strategies.

Prevalence of Metabolic Syndrome and Association with Grip Strength in Older Adults: Findings from the HOPE Study.

OBJECTIVE: To determine the prevalence of metabolic syndrome (MetS) in older adults and assess the association of MetS and adverse outcomes with handgrip strength (HGS), HGS/body weight (BWT), and HGS/body mass index (BMI). METHODS: A cross-sectional population study in Singapore. Data were collected on demographics, HGS, Timed-Up and Go (TUG), fasting glucose, lipid profile, blood pressure, waist circumference, frailty status, and cognition in 722 older adults ≥65 years old. MetS was defined using the Modified ATP III for Asians where at least three of the following conditions must be fulfilled, central obesity, high blood glucose (or diagnosed diabetes mellitus), high blood pressure (or diagnosed hypertension), low high-density lipoprotein, and high triglycerides. The waist circumference in the Modified ATP III for Asians is ≥90 cm for males or ≥80 cm for females. HGS and HGS normalized by BWT or BMI were used for the association. RESULTS: The prevalence of MetS in older adults was 41.0%, and those ≥85 years old 50.0%. The prevalence was higher in females ≥70 years old, with 8 in 10 females ≥85 years having MetS. After adjusting for age, years of education, physical exercise, as well as history of smoking and alcohol consumption, higher HGS normalized by BWT or BMI was significantly associated with lower odds of having MetS (OR: 0.51,95% CI 0.43-0.61, p<0.01) and (OR: 0.13, 95% CI 0.07-0.24, p<0.01). CONCLUSION: Almost 1 in 2 older adults had MetS, with the prevalence in females much higher than that in males over 70 years old. Our findings suggest that both HGS/BWT and HGS/BMI had a significant negative association with MetS, its components, and adverse effects. Further studies are needed to validate the association and to determine optimal cutoffs of HGS/BWT and HGS/BMI for MetS, and the effectiveness of interventions in averting the risk.

Factors associated with social isolation in community-dwelling older adults: a cross-sectional study.

PURPOSE: Social isolation in older adults is a major public health problem and associated with increased morbidity and mortality. There are limited data on the association between social isolation and physical function including gait speed. Hence, this study is to determine the prevalence of social isolation and its association with gait speed, frailty, cognition, depression and comorbidities amongst community-dwelling older adults. METHODS: Social isolation, depression, frailty and perceived general health were assessed using 6-item Lubben Social Network Scale (LSNS-6), Geriatric Depression Scale (GDS), FRAIL scale and EuroQol EQ-5D-5L questionnaire which includes EQ Visual Analogue Scale (EQ-VAS), respectively. Cognition was assessed using the Chinese Mini Mental State Examination (cMMSE), while physical performance test included gait speed and short physical performance battery test. Binary logistic regression was performed to determine the influence of socio-demographic, medical, functional and cognitive variables on social isolation. RESULTS: Out of 202 participants, 27.7% were robust, 66.8% of participants were pre-frail, and 5.4% of participants were frail. Almost half (45.5%, n = 92) of the participants were found to be at risk of social isolation. A poor social network was negatively associated with mean gait speed (OR = 0.674, CI 0.464-0.979, p = 0.039), EQ-VAS (OR = 0.561, CI 0.390-0.806, p < 0.01) and cMMSE (OR = 0.630, 95% CI 0.413-0.960, p = 0.032). CONCLUSION: Almost half of older adults in the community are at risk of social isolation with a very significant association with gait speed, cMMSE and EQ-VAS scores.

Determinants of eating at local and western fast-food venues in an urban Asian population: a mixed methods approach.

BACKGROUND: Like several Southeast Asian countries, Singapore has a complex eating-out environment and a rising eating-out prevalence. However the determinants and drivers of eating-out in urban Asian environments are poorly understood. METHODS: We examined the socio-demographic characteristics of persons who frequently ate away from home in local eateries called hawker centres and Western fast-food restaurants, using data from 1647 Singaporean adults participating in the National Nutrition Survey (NNS) 2010. We also assessed the underlying drivers of eating out and evaluated if these were different for eating at local eateries compared to Western fast-food restaurants using 18 focus group discussions of women (130 women). RESULTS: Participants reported a high eating-out frequency with 77.3% usually eating either breakfast, lunch or dinner at eateries. Main venues for eating-out included hawker centres (61.1% usually ate at least 1 of 3 daily meals at this venue) and school/workplace canteens (20.4%). A minority of participants (1.9%) reported usually eating at Western fast-food restaurants. Younger participants and those of Chinese and Malay ethnicity compared to Indians were more likely to eat at Western fast-food restaurants. Chinese and employed persons were more likely to eat at hawker centres. The ready availability of a large variety of affordable and appealing foods appeared to be a primary driver of eating out, particularly at hawker centres. CONCLUSIONS: Our findings highlight the growing importance of eating-out in an urban Asian population where local eating venues play a more dominant role compared with Western fast-food chains. Interventions focusing on improving the food quality at venues for eating out are important to improve the diet of urban Asian populations.

Development of a Semi-Quantitative Food Frequency Questionnaire to Assess the Dietary Intake of a Multi-Ethnic Urban Asian Population.

Assessing habitual food consumption is challenging in multi-ethnic cosmopolitan settings. We systematically developed a semi-quantitative food frequency questionnaire (FFQ) in a multi-ethnic population in Singapore, using data from two 24-h dietary recalls from a nationally representative sample of 805 Singapore residents of Chinese, Malay and Indian ethnicity aged 18-79 years. Key steps included combining reported items on 24-h recalls into standardized food groups, developing a food list for the FFQ, pilot testing of different question formats, and cognitive interviews. Percentage contribution analysis and stepwise regression analysis were used to identify foods contributing cumulatively ≥90% to intakes and individually ≥1% to intake variance of key nutrients, for the total study population and for each ethnic group separately. Differences between ethnic groups were observed in proportions of consumers of certain foods (e.g., lentil stews, 1%-47%; and pork dishes, 0%-50%). The number of foods needed to explain variability in nutrient intakes differed substantially by ethnic groups and was substantially larger for the total population than for separate ethnic groups. A 163-item FFQ covered >95% of total population intake for all key nutrients. The methodological insights provided in this paper may be useful in developing similar FFQs in other multi-ethnic settings.

Use of auto-segmentation in the delineation of target volumes and organs at risk in head and neck.

BACKGROUND: Manual delineation of structures in head and neck cancers is an extremely time-consuming and labor-intensive procedure. With centers worldwide moving towards the use of intensity-modulated radiotherapy and adaptive radiotherapy, there is a need to explore and analyze auto-segmentation (AS) software, in the search for a faster yet accurate method of structure delineation. MATERIAL AND METHODS: A search for studies published after 2005 comparing AS and manual delineation in contouring organ at risks (OARs) and target volume for head and neck patients was conducted. The reviewed results were then categorized into arguments proposing and opposing the review title. RESULTS: Ten studies were reviewed and derived results were assessed in terms of delineation time-saving ability and extent of delineation accuracy. The influence of other external factors (observer variability, AS strategies adopted and stage of disease) were also considered. Results were conflicting with some studies demonstrating great potential in replacing manual delineation whereas other studies illustrated otherwise. Six of 10 studies investigated time saving; the largest time saving reported being 59%. However, one study found that additional time of 15.7% was required for AS. Four studies reported AS contours to be between 'reasonably good' and 'better quality' than the clinically used contours. Remaining studies cited lack of contrast, AS strategy used and the need for physician intervention as limitations in the standardized use of AS. DISCUSSION: The studies demonstrated significant potential of AS as a useful delineation tool in contouring target volumes and OARs in head and neck cancers. However, it is evident that AS cannot totally replace manual delineation in contouring some structures in the head and neck and cannot be used independently without human intervention. It is also emphasized that delineation studies should be conducted locally so as to evaluate the true value of AS in head and neck cancers in a specific center.

Role of dietary long-chain polyunsaturated fatty acids in infant allergies and respiratory diseases.

Maternal nutrition has critical effects on the developing structures and functions of the fetus. Malnutrition during pregnancy can result in low birth weight and small for gestational age babies, increase risk for infection, and impact the immune system. Long-chain polyunsaturated fatty acids (PUFAs) have been reported to have immunomodulatory effects. Decreased consumption of omega-6 PUFAs, in favor of more anti-inflammatory omega-3 PUFAs in modern diets, has demonstrated the potential protective role of omega-3 PUFAs in allergic and respiratory diseases. In this paper, we examine the role of PUFAs consumption during pregnancy and early childhood and its influence on allergy and respiratory diseases. PUFAs act via several mechanisms to modulate immune function. Omega-3 PUFAs may alter the T helper (Th) cell balance by inhibiting cytokine production which in turn inhibits immunoglobulin E synthesis and Th type 2 cell differentiation. PUFAs may further modify cellular membrane, induce eicosanoid metabolism, and alter gene expression. These studies indicate the benefits of omega-3 PUFAs supplementation. Nevertheless, further investigations are warranted to assess the long-term effects of omega-3 PUFAs in preventing other immune-mediated diseases, as well as its effects on the later immunodefense and health status during early growth and development.

"What is this?" Gesture as a potential cue to identify referents in discourse.

This study explores whether caregivers follow the discourse-pragmatic principle of information status of referents (given vs. new) in their gestures and how children respond to their caregivers' gestures. Chinese and American caregivers were videotaped while interacting spontaneously with their children. Their speech and gestures were coded for referential expressions. Even though Chinese caregivers gestured more often than American caregivers, we found that both groups produced more gestures when asking their children to identify new referents than when asking their children to identify given referents. In addition, both groups of children were sensitive to the gestures accompanying new referents and using these gestures to identify the referents. Thus, we conclude that gesture serves as a potential cue for both caregivers and children to identify referents according to the discourse-pragmatic principle of information status.

Cholesteric liquid crystals doped with dodecylamine for detecting aldehyde vapors.

In this paper, we report a study of using cholesteric liquid crystals (CLCs) doped with dodecylamine for detecting aldehyde vapors. CLCs doped with dodecylamine show color change from red to yellow-green upon exposure to 300 ppmv pentyl aldehyde within 60 s. In contrast, no colorimetric response is observed when pure CLCs are used. Characterization by using FT-IR shows that the possible mechanism responsible for the colorimetric response is the formation of an imine bond between dodecylamine and pentyl aldehyde. A new C=N peak at 1670 cm(-1) appears in the spectrum after the exposure to aldehyde vapors. The CLCs doped with dodecylamine show good selectivity for pentyl aldehyde; they do not respond to 200 ppmv pentyl alcohol, pentylamine, acetone, ethanol, and water vapor. This study demonstrates the potential applications of doped CLCs as low-cost and portable gas sensors.