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1.
Polymers (Basel) ; 15(12)2023 Jun 12.
Artículo en Inglés | MEDLINE | ID: mdl-37376300

RESUMEN

Dragon fruit, also called pitaya or pitahaya, is in the family Cactaceae. It is found in two genera: 'Selenicereus' and 'Hylocereus'. The substantial growth in demand intensifies dragon fruit processing operations, and waste materials such as peels and seeds are generated in more significant quantities. The transformation of waste materials into value-added components needs greater focus since managing food waste is an important environmental concern. Two well-known varieties of dragon fruit are pitaya (Stenocereus) and pitahaya (Hylocereus), which are different in their sour and sweet tastes. The flesh of the dragon fruit constitutes about two-thirds (~65%) of the fruit, and the peel is approximately one-third (~22%). Dragon fruit peel is believed to be rich in pectin and dietary fibre. In this regard, extracting pectin from dragon fruit peel can be an innovative technology that minimises waste disposal and adds value to the peel. Dragon fruit are currently used in several applications, such as bioplastics, natural dyes and cosmetics. Further research is recommended for diverging its development in various areas and maturing the innovation of its usage.

2.
BMC Public Health ; 23(1): 241, 2023 02 04.
Artículo en Inglés | MEDLINE | ID: mdl-36737719

RESUMEN

BACKGROUND: Despite impressive strides in health, social protection, and education, children continue to experience high rates of child maltreatment in Malaysia. This mixed-methods study assessed the feasibility of a five-session, social learning-based parenting program delivered by government staff in a community setting to reduce violence against children. METHODS: Parents of children from birth to 17 years were recruited from two communities near Kuala Lumpur to participate in the government-run program called the Naungan Kasih Positive Parenting Program ("Protecting through Love" in Bahasa Melayu). Quantitative data from female caregivers (N = 74) and children ages 10-17 (N = 26) were collected along with qualitative interviews and focus groups with parents, children, and facilitators. The primary outcome was child maltreatment with secondary outcomes including neglect, positive parenting, acceptability of corporal punishment, harsh parenting, positive discipline, and child behavior problems. Multilevel Poisson regression and multilevel linear regression were conducted to compare baseline and post-test outcomes. Qualitative interviews and focus groups examined how participants experienced the program utilizing a thematic analysis approach. RESULTS: Quantitative analyses found pre-post reductions in overall child maltreatment, physical abuse, emotional abuse, attitudes supporting corporal punishment, parent sense of inefficacy, and child behavior problems. There were no reported changes on positive and harsh parenting, parental mental health, and marital satisfaction, nor were there any other significant changes reported by children. Qualitative findings suggested that the program had tangible benefits for female caregivers involved in the program, with the benefits extending to their family members. CONCLUSIONS: This feasibility study is one of the few studies in Southeast Asia that examined the feasibility and initial program impact of a parenting program delivered by government staff to families with children across the developmental spectrum from birth to 17 years. Promising results suggest that the program may reduce child maltreatment across a range of child ages. Findings also indicate areas for program improvement prior to further delivery and testing, including additional training and content on sexual and reproductive health, parenting children with disabilities, and online child protection.


Asunto(s)
Maltrato a los Niños , Responsabilidad Parental , Niño , Humanos , Femenino , Adolescente , Responsabilidad Parental/psicología , Estudios de Factibilidad , Malasia , Violencia , Padres/psicología , Maltrato a los Niños/prevención & control , Maltrato a los Niños/psicología
3.
Arch Razi Inst ; 77(3): 1181-1184, 2022 06.
Artículo en Inglés | MEDLINE | ID: mdl-36618308

RESUMEN

Klebsiella pneumoniae is a gram-negative bacterium that causes serious illnesses, including pneumonia, liver abscess, meningitis, bloodstream infections, and urinary tract infections (UTIs). This study aimed to isolate and diagnose K. pneumoniae from clinical specimens of urine from patients with UTIs and perform molecular detection of the blaSHV-la gene in K. pneumonia in the Najaf Province, Iraq. The study included 100 clinical specimens from October 2021 to March 2022. As an initial diagnosis, K. pneumoniae isolates were diagnosed based on culture and biochemical features. Apart from the usage of polymerase chain reaction (PCR) technology to identify the blaSHV-la gene, the final diagnostic was achieved by the automated Vitek-2 compact system. The biochemical findings revealed that 40 out of every 100 isolates tested positive for K. pneumoniae. These results were validated by Vitek, which revealed that 40/100 of the samples tested positive for K. pneumoniae, and by PCR utilizing the blaSHV-la gene, which showed that 13/40 of the samples tested positive for K. pneumoniae isolated from the urine of patients with UTIs. In conclusion, the results indicated that the use of the Vitek-2 technique was required to confirm the accurate identification of the pathogen. Klebsiella pneumoniae clinical isolates showed multidrug resistance to antibiotics commonly used to treat UTIs. The blaSHV gene encoded for Extended-spectrum beta-lactam antibiotic was found almost in K. pneumoniae isolates.


Asunto(s)
Infecciones por Klebsiella , Neumonía , Infecciones Urinarias , Humanos , beta-Lactamasas/genética , beta-Lactamasas/uso terapéutico , Farmacorresistencia Bacteriana Múltiple/genética , Irak/epidemiología , Infecciones por Klebsiella/tratamiento farmacológico , Infecciones por Klebsiella/epidemiología , Infecciones por Klebsiella/microbiología , Klebsiella pneumoniae/genética , Pruebas de Sensibilidad Microbiana , Infecciones Urinarias/microbiología
4.
Sci Rep ; 11(1): 19541, 2021 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-34599233

RESUMEN

Accurate state of charge (SOC) estimation of lithium-ion (Li-ion) batteries is crucial in prolonging cell lifespan and ensuring its safe operation for electric vehicle applications. In this article, we propose the deep learning-based transformer model trained with self-supervised learning (SSL) for end-to-end SOC estimation without the requirements of feature engineering or adaptive filtering. We demonstrate that with the SSL framework, the proposed deep learning transformer model achieves the lowest root-mean-square-error (RMSE) of 0.90% and a mean-absolute-error (MAE) of 0.44% at constant ambient temperature, and RMSE of 1.19% and a MAE of 0.7% at varying ambient temperature. With SSL, the proposed model can be trained with as few as 5 epochs using only 20% of the total training data and still achieves less than 1.9% RMSE on the test data. Finally, we also demonstrate that the learning weights during the SSL training can be transferred to a new Li-ion cell with different chemistry and still achieve on-par performance compared to the models trained from scratch on the new cell.

5.
Med J Malaysia ; 76(1): 98-100, 2021 01.
Artículo en Inglés | MEDLINE | ID: mdl-33510117

RESUMEN

Around June 2020, many institutions restarted full operating schedules to clear the backlog of postponed surgeries because of the first wave in the COVID-19 pandemic. In an online survey distributed among anaesthestists in Asian countries at that time, most of them described their safety concerns and recommendations related to the supply of personal protective equipment and its usage. The second concern was related to pre-operative screening for all elective surgical cases and its related issues. The new norm in practice was found to be non-standardized and involved untested devices or workflow that have since been phased out with growing evidence. Subsequent months after reinstating full elective surgeries tested the ability of many hospitals in handling the workload of non-COVID surgical cases together with rising COVID-19 positive cases in the second and third waves when stay-at-home orders eased.


Asunto(s)
Anestesistas , COVID-19/diagnóstico , COVID-19/prevención & control , Exposición Profesional/prevención & control , Salud Laboral , Equipo de Protección Personal/provisión & distribución , Procedimientos Quirúrgicos Electivos , Humanos , Periodo Preoperatorio , SARS-CoV-2 , Encuestas y Cuestionarios , Flujo de Trabajo
6.
Nat Commun ; 11(1): 3792, 2020 Jul 30.
Artículo en Inglés | MEDLINE | ID: mdl-32733048

RESUMEN

Three-phase induction motors (TIMs) are widely used for machines in industrial operations. As an accurate and robust controller, fuzzy logic controller (FLC) is crucial in designing TIMs control systems. The performance of FLC highly depends on the membership function (MF) variables, which are evaluated by heuristic approaches, leading to a high processing time. To address these issues, optimisation algorithms for TIMs have received increasing interest among researchers and industrialists. Here, we present an advanced and efficient quantum-inspired lightning search algorithm (QLSA) to avoid exhaustive conventional heuristic procedures when obtaining MFs. The accuracy of the QLSA based FLC (QLSAF) speed control is superior to other controllers in terms of transient response, damping capability and minimisation of statistical errors under diverse speeds and loads. The performance of the proposed QLSAF speed controller is validated through experiments. Test results under different conditions show consistent speed responses and stator currents with the simulation results.

7.
Malays J Pathol ; 42(1): 65-70, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-32342932

RESUMEN

INTRODUCTION: Homicide is the act of killing one human being by another, encompassing death as a result of criminal act including justifiable homicide such as judicial killing and self-defence. This study aimed to ascertain the epidemiology and patterns of injury of homicide victims. MATERIALS AND METHODS: We reviewed records of medico-legal autopsy cases performed at the Department of Forensic Medicine, Hospital Sungai Buloh, for a period of five years, from January 2012 until December 2016. Subjects' demographic data such as age, gender, nationality, ethnicity and cause of death were recorded. RESULTS: A total of 122 homicide cases were documented. 90% of the victims were 18 to 65 years old. Males contributed 80% of the subjects. An alarming 42% of the subjects comprised of non-Malaysians. Indonesian subjects contributed one-third of the non-citizen category, followed by Bangladeshis at 20.4%. Other nationalities were Burmese, Nepalese, Pakistani, Vietnamese and unspecified. Among Malaysians, 50% of the subjects were Indians, followed by Malay (31.5%) and Chinese (17.8%). Sharp and blunt force traumas were the most common injuries found, contributing 33% and 32% respectively. Asphyxiation and firearm injuries recorded an almost similar frequency, contributing 25% in combination. Other patterns included combined sharp and blunt objects (4.9%) and burns (3%). CONCLUSIONS: A large number of immigrants in the country have significantly increased the forensic casework. Sharp and blunt objects continue to be the weapon of choice due to its easy accessibility. As domestic violence including fatal spousal and child abuse continue to rise, in-depth study in the area is warranted.


Asunto(s)
Homicidio/estadística & datos numéricos , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Autopsia , Niño , Emigrantes e Inmigrantes , Femenino , Homicidio/etnología , Humanos , Malasia , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Adulto Joven
8.
Malays J Pathol ; 42(1): 77-84, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-32342934

RESUMEN

INTRODUCTION: Procalcitonin (PCT) has recently emerged as a marker for diagnosing infection. This study aimed to compare the performance of PCT and other infection markers in diagnosing infected diabetic foot ulcer (IDFU). MATERIALS AND METHODS: A total of 128 diabetic patients with foot ulcers were recruited and divided into two groups, consisting of 73 patients in the IDFU group and 55 in the non-infected diabetic foot ulcer (NIDFU). The severity of infection in IDFU patients was graded based on the Infectious Disease Society of America-International Working Group on the Diabetic Foot classification. Blood samples from all the patients were collected for measurement of PCT, high sensitivity C-reactive protein (hs-CRP) and white cell count (WBC). The area under the receiver operating curves (AUC) were then constructed and analysed. RESULTS: PCT, hs-CRP and WBC levels were significantly higher in the IDFU group compared to NIDFU with hs-CRP demonstrated the highest AUC (0.91; p <0.001) followed by PCT (0.814; p < 0.001) and lastly WBC (0.775; p < 0.001). The best cut off value, sensitivity and specificity for the presence of infection in diabetic foot, were 3.47 mg/dL, 80% and 89% for hs-CRP, 0.11 ng/ml, 70% and 87% for PCT and 11.8x109/L, 60% and 90% for WBC. All the infection markers showed significant positive correlations with infection severity of DFU. CONCLUSION: This study showed that hs-CRP is a more sensitive marker for diagnosing IDFU. Although PCT is useful in differentiating IDFU from NIDFU, the use of PCT is not necessary as it adds little value to the current practice.


Asunto(s)
Infecciones Bacterianas/sangre , Infecciones Bacterianas/diagnóstico , Biomarcadores/sangre , Pie Diabético/complicaciones , Polipéptido alfa Relacionado con Calcitonina/sangre , Adulto , Anciano , Infecciones Bacterianas/etiología , Proteína C-Reactiva/análisis , Estudios Transversales , Pie Diabético/microbiología , Femenino , Humanos , Masculino , Persona de Mediana Edad
9.
Malays Orthop J ; 14(2)2020 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-32313613

RESUMEN

With the increasing number of COVID-19 cases and related deaths worldwide, we decided to share the development of this condition in Singapore and Malaysia. First few cases were diagnosed in the two countries at the end of January 2020, and the numbers have surged to thousands by end of March 2020. We will focus on strategies adopted by the government and also the Orthopaedic community of the two countries up till the beginning of April 2020. We hope that by sharing of relevant information and knowledge on how we are managing the COVID-19 condition, we can help other communities, and health care workers to more effectively overcome this pandemic.

10.
Sci Rep ; 10(1): 4687, 2020 Mar 13.
Artículo en Inglés | MEDLINE | ID: mdl-32170100

RESUMEN

State of charge (SOC) is a crucial index used in the assessment of electric vehicle (EV) battery storage systems. Thus, SOC estimation of lithium-ion batteries has been widely investigated because of their fast charging, long-life cycle, and high energy density characteristics. However, precise SOC assessment of lithium-ion batteries remains challenging because of their varying characteristics under different working environments. Machine learning techniques have been widely used to design an advanced SOC estimation method without the information of battery chemical reactions, battery models, internal properties, and additional filters. Here, the capacity of optimized machine learning techniques are presented toward enhanced SOC estimation in terms of learning capability, accuracy, generalization performance, and convergence speed. We validate the proposed method through lithium-ion battery experiments, EV drive cycles, temperature, noise, and aging effects. We show that the proposed method outperforms several state-of-the-art approaches in terms of accuracy, adaptability, and robustness under diverse operating conditions.

11.
Artículo en Inglés | WPRIM (Pacífico Occidental) | ID: wpr-822297

RESUMEN

@#With the increasing number of COVID-19 cases and related deaths worldwide, we decided to share the development of this condition in Singapore and Malaysia. First few cases were diagnosed in the two countries at the end of January 2020, and the numbers have surged to thousands by end of March 2020. We will focus on strategies adopted by the government and also the Orthopaedic community of the two countries up till the beginning of April 2020. We hope that by sharing of relevant information and knowledge on how we are managing the COVID-19 condition, we can help other communities, and health care workers to more effectively overcome this pandemic.

12.
Int Forum Allergy Rhinol ; 8(5): 614-619, 2018 05.
Artículo en Inglés | MEDLINE | ID: mdl-29227037

RESUMEN

BACKGROUND: No high-fidelity animal model exists to examine prospective wound healing following vascularized reconstruction of the skull base. Such a model would require the ability to study the prospective behavior of vascularized mucosal repairs of large dural and arachnoid defects within the intranasal environment. The objective of this study was to therefore develop and validate a novel, in vivo, transfrontal sheep model of cranial base repair using vascularized sinonasal mucosa. METHODS: Twelve transfrontal craniotomy and 1.5-cm durotomy reconstructions were performed in 60-kg to 70-kg Dorset/Ovis Aries sheep using vascularized mucosa with or without an adjunctive Biodesign™ underlay graft (n = 6 per group). Histologic outcomes were graded (scale, 0 to 4) by a blinded veterinary histopathologist after 7, 14, and 28 days for a range of wound healing parameters. RESULTS: All sheep tolerated the surgery, which required 148 ± 33 minutes. By day 7, the mucosa was fully adherent with complete partitioning of the sinus and intracranial compartments. Fibroblast infiltration and flap neovascularization scores significantly increased between day 7 (0.3 ± 0.5 and 0.0 ± 0.0) and day 28 (4.0 ± 0.0, p = 0.01 and 2.0 ± 0.8, p = 0.01; respectively), while hemorrhage scores significantly decreased from 2.5 ± 0.6 to 0.0 ± 0.0 (p = 0.01). The inflammatory scores were not significantly different between the heterologous graft and control sides. CONCLUSION: The described sheep model accurately reflects prospective intranasal wound healing following vascularized mucosal reconstruction of dural defects. This model can be used in future studies to examine novel reconstructive materials, tissue glues, and transmucosal drug delivery to the central nervous system.


Asunto(s)
Craneotomía , Mucosa Nasal/cirugía , Procedimientos de Cirugía Plástica , Base del Cráneo/cirugía , Colgajos Quirúrgicos , Animales , Modelos Animales de Enfermedad , Humanos , Complicaciones Posoperatorias , Ovinos , Base del Cráneo/anatomía & histología , Alotrasplante Compuesto Vascularizado , Cicatrización de Heridas
13.
ScientificWorldJournal ; 2014: 183741, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-25136648

RESUMEN

This paper proposes a small sized, low-cost multiband monopole antenna which can cover the WiMAX bands and C-band. The proposed antenna of 20 × 20 mm(2) radiating patch is printed on cost effective 1.6 mm thick fiberglass polymer resin dielectric material substrate and fed by 4 mm long microstrip line. The finite element method based, full wave electromagnetic simulator HFSS is efficiently utilized for designing and analyzing the proposed antenna and the antenna parameters are measured in a standard far-field anechoic chamber. The experimental results show that the prototype of the antenna has achieved operating bandwidths (voltage stand wave ratio (VSWR) less than 2) 360 MHz (2.53-2.89 GHz) and 440 MHz (3.47-3.91 GHz) for WiMAX and 1550 MHz (6.28-7.83 GHz) for C-band. The simulated and measured results for VSWR, radiation patterns, and gain are well matched. Nearly omnidirectional radiation patterns are achieved and the peak gains are of 3.62 dBi, 3.67 dBi, and 5.7 dBi at 2.66 GHz, 3.65 GHz, and 6.58 GHz, respectively.


Asunto(s)
Tecnología Inalámbrica/instrumentación , Diseño de Equipo
14.
Singapore Med J ; 50(8): 822-6, 2009 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-19710984

RESUMEN

INTRODUCTION: The AdeABC pump of Acinetobacter spp. confers resistance to various antibiotic classes. This pump is composed of the AdeA, AdeB, and AdeC proteins where AdeB is a member of the resistance-nodulation-division efflux pump superfamily. The adeA, adeB, and adeC genes are contiguous and adjacent to adeS and adeR, which are transcribed in the opposite direction and which specify proteins homologous to sensors and regulators of two-component systems, respectively. In this study, an attempt is made to elucidate the role of the AdeABC efflux pump in carbapenem resistance in Acinetobacter spp. METHODS: 39 carbapenem-resistant clinical isolates of Acinetobacter spp. were used. Minimum inhibitory concentrations were evaluated using the agar dilution method according to Clinical and Laboratory Standards Institute standards. The presence of carbapenem hydrolysing oxacillinases and AdeABC efflux pump genes were determined by PCR amplification. Subsequently, each gene was inactivated by plasmid insertion in order to study the contribution of these genes in developing antibiotic resistance and the resulting mutants were tested for their antimicrobial susceptibilities. RESULTS: Among the multidrug-resistant strains, 36 strains had all the three (A, B, C) genes detected, while the remaining three strains had one or two of the genes detected. Inactivation of these individual genes showed decreased antimicrobial susceptibility indicating its contribution towards the development of antimicrobial resistance. CONCLUSION: The presence of AdeABC multidrug efflux pump plays a major role in the development of antimicrobial resistance in Acinetobacter spp. The presence of either one or an interplay between these genes may have an effect on antimicrobial resistance in Acinetobacter spp.


Asunto(s)
Infecciones por Acinetobacter/microbiología , Acinetobacter/genética , Proteínas Bacterianas/genética , Proteínas de Transporte de Membrana/genética , Tienamicinas/farmacología , Acinetobacter/fisiología , Infecciones por Acinetobacter/genética , Antibacterianos/farmacología , Proteínas Bacterianas/fisiología , Carbapenémicos/farmacología , Farmacorresistencia Bacteriana Múltiple/genética , Humanos , Malasia , Proteínas de Transporte de Membrana/fisiología , Meropenem , Modelos Genéticos , Mutación , Plásmidos/metabolismo , Reacción en Cadena de la Polimerasa , Análisis de Secuencia de ADN
15.
Med J Malaysia ; 61(1): 114-6, 2006 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-16708749

RESUMEN

Pulmonary hypertension in pregnancy is a rare condition but is associated with a high mortality. We report the case of a 29 year old female in early pregnancy with Protein C and S deficiency with recurrent deep venous thrombosis and pulmonary embolism and subsequent secondary pulmonary hypertension. The patient was counselled and consented for termination of pregnancy with tubal sterilization. She was administered continuous spinal anaesthesia with invasive monitoring. The successful anaesthetic management of this condition is described.


Asunto(s)
Anestesia Raquidea/métodos , Hipertensión Pulmonar/etiología , Complicaciones Hematológicas del Embarazo , Embolia Pulmonar/fisiopatología , Esterilización Tubaria , Trombofilia/fisiopatología , Trombosis de la Vena/fisiopatología , Aborto Terapéutico , Adulto , Femenino , Humanos , Embarazo , Complicaciones Cardiovasculares del Embarazo/etiología , Deficiencia de Proteína C/fisiopatología , Deficiencia de Proteína S/fisiopatología , Factores de Tiempo
17.
Int J Obstet Anesth ; 12(1): 23-7, 2003 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-15676316

RESUMEN

A 5-year retrospective survey of anaesthesia for caesarean section for mild/moderate and severe preeclampsia was performed, covering the period between 1 January 1996 and 31 December 2000. One hundred and twenty-one cases of non-labouring preeclamptic patients receiving spinal or epidural anaesthesia for caesarean section were included for analysis. Comparisons were made of the lowest blood pressures recorded before induction of anaesthesia, during the period from induction to delivery and the period from delivery to the end of operation. The decreases in blood pressure were similar after spinal and epidural anaesthesia. The use of intravenous fluids and ephedrine were also comparable in the two anaesthetic groups. There was no difference in maternal or neonatal outcome. Our result supports the use of spinal anaesthesia in preeclamptic women.

18.
Ground Water ; 39(5): 702-12, 2001.
Artículo en Inglés | MEDLINE | ID: mdl-11554248

RESUMEN

Recharge areas of spring systems can be hard to identify, but they can be critically important for protection of a spring resource. A recharge area for a spring complex in southern Wisconsin was delineated using a variety of complementary techniques. A telescopic mesh refinement (TMR) model was constructed from an existing regional-scale ground water flow model. This TMR model was formally optimized using parameter estimation techniques; the optimized "best fit" to measured heads and fluxes was obtained by using a horizontal hydraulic conductivity 200% larger than the original regional model for the upper bedrock aquifer and 80% smaller for the lower bedrock aquifer. The uncertainty in hydraulic conductivity was formally considered using a stochastic Monte Carlo approach. Two-hundred model runs used uniformly distributed, randomly sampled, horizontal hydraulic conductivity values within the range given by the TMR optimized values and the previously constructed regional model. A probability distribution of particles captured by the spring, or a "probabilistic capture zone," was calculated from the realistic Monte Carlo results (136 runs of 200). In addition to portions of the local surface watershed, the capture zone encompassed areas outside of the watershed--demonstrating that the ground watershed and surface watershed do not coincide. Analysis of water collected from the site identified relatively large contrasts in chemistry, even for springs within 15 m of one another. The differences showed a distinct gradation from Ordovician-carbonate-dominated water in western spring vents to Cambrian-sandstone-influenced water in eastern spring vents. The difference in chemistry was attributed to distinctive bedrock geology as demonstrated by overlaying the capture zone derived from numerical modeling over a bedrock geology map for the area. This finding gives additional confidence to the capture zone calculated by modeling.


Asunto(s)
Modelos Teóricos , Método de Montecarlo , Abastecimiento de Agua , Fenómenos Geológicos , Geología , Presión , Agua/química , Movimientos del Agua
19.
Am J Bot ; 87(4): 447-55, 2000 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-10766716

RESUMEN

We studied the development of leaf characters in two Southeast Asian dipterocarp forest trees under different photosynthetic photon flux densities (PFD) and spectral qualities (red to far-red, R:FR). The two species, Hopea helferi and H. odorata, are taxonomically closely related but differ in their ecological requirements; H. helferi is more drought tolerant and H. odorata more shade tolerant. Seedlings were grown in replicated shadehouse treatments of differing PFD and R:FR. We measured or calculated (1) leaf and tissue thicknesses; (2) mesophyll parenchyma, air space, and lignified tissue volumes; (3) mesophyll air volumes (V(mes)/A(surf)) and surfaces (A(mes)/A(surf)); (4) palisade cell length and width; (5) chlorophyll/cm and a/b; (6) leaf absorption; and (7) attenuance/absorbance at 652 and 550 nm. These characters varied in response to light conditions in both taxa. Characters were predominantly affected by PFD, and R:FR slightly influenced many characters. Leaf characters of H. odorata were more plastic in response to treatment conditions. Characters were correlated with each other in a complex fashion. Variation in leaf anatomy is most likely a consequence of increasing leaf thickness in both taxa, which may increase mechanical strength and defense against herbivory in more exposed environments. Variation in leaf optical properties was most likely affected by pigment photo-bleaching in treatments of more intense PFD and was not correlated with A(max). The greater plasticity of leaf responses in H. odorata helps explain the acclimation over the range of light conditions encountered by this shade-tolerant taxon. The dense layer of scales on the leaf undersurface and other anatomical characters in H. helferi reduced gas exchange and growth in this drought-tolerant tree.

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