Influence of pore fluid salinity on shrinkage and water retention characteristics of biochar amended kaolin for landfill liner application.

Biochar amended clay layer has emerged as a sustainable hydraulic barrier for hazardous municipal waste containment system. The effects of pore fluid salinity on soil shrinkage and water retention characteristics of biochar amended clay are unknown. This study aims to investigate the behavior of soil shrinkage and water retention of biochar amended kaolin under different pore fluid salinity. A series of volumetric shrinkage and water retention tests were conducted on biochar amended kaolin in sodium chloride solution at initial concentrations of 1 %, 5 %, and 10 %. Biochar addition increased the shrinkage limit and minimum void ratio of kaolin by up to 17 % and 11 %, respectively. Air entry value of kaolin increased by 6-88 times with an increase in pore fluid salinity, caused by interparticle aggregation. Micrographs showed that biochar intrapore was filled by kaolin particles, partially hindering the interparticle aggregation of clay in the salt solution. Biochar addition lowered zeta potential on the surface of kaolin particles by 50-75 %, indicating that the immobilisation of excess sodium ions was achieved by biochar. Correspondingly, osmotic suction of pore fluid decreased by 21-64 % due to biochar's ion absorption. The findings highlighted that biochar addition to kaolin specimens minimises NaCl-induced soil shrinkage and reduces the pore fluid salinity. This study indicates that biochar could be potentially helpful for desalinisation and mitigating volumetric change issues for geo-environmental infrastructures.

MEK inhibitor resistance mechanisms and recent developments in combination trials.

The mitogen-activated protein kinase (MAPK) pathway plays a vital role in cellular processes such as gene expression, cell proliferation, cell survival, and apoptosis. Also known as the RAS-RAF-MEK-ERK pathway, the MAPK pathway has been implicated in approximately one-third of all cancers. Mutations in RAS or RAF genes such as KRAS and BRAF are common, and these mutations typically promote malignancies by over-activating MEK and ERK downstream, which drives sustained cell proliferation and uninhibited cell growth. Development of drugs targeting this pathway has been a research area of great interest, especially drugs targeting the inhibition of MEK. In vitro and clinical studies have shown promise for certain MEK inhibitors (MEKi) , and MEKi have become the first treatment option for certain cancers. Despite promising results, not all patients have a response to MEKi, and mechanisms of resistance typically arise in patients who do have a positive initial response. This paper summarizes recent developments regarding MEKi, the mechanisms of adaptive resistance to MEKi, and the potential solutions to the issue of adaptive MEKi resistance.

Maintaining breast cancer care in the face of COVID-19.

The battle of COVID-19 is currently at different levels of intensity in each country and even each city. The authors have prepared succinct recommendations regarding the care of patients with breast cancer, divided into phases that can easily be adapted to each units' needs and resources, and stepped up or stepped down according to escalating and de-escalating circumstances. The structure can also be transposed easily to different cancer types, enabling continued provision of best standards of care despite unprecedented stressors. Surgery must go on.

Barriers to implementing a national health screening program for men in Malaysia: An online survey of healthcare providers.

INTRODUCTION: This study aimed to determine the views and practices of healthcare providers and barriers they encountered when implementing the national health screening program for men in a public primary care setting in Malaysia. METHODS: An online survey was conducted among healthcare providers across public health clinics in Malaysia. All family medicine specialists, medical officers, nurses and assistant medical officers involved in the screening program for adult men were invited to answer a 51-item questionnaire via email or WhatsApp. The questionnaire comprised five sections: participants' socio-demographic information, current screening practices, barriers and facilitators to using the screening tool, and views on the content and format of the screening tool. RESULTS: A total of 231 healthcare providers from 129 health clinics participated in this survey. Among them, 37.44% perceived the implementation of the screening program as a "top-down decision." Although 37.44% found the screening tool for adult men "useful," some felt that it was "time consuming" to fill out (38.2%) and "lengthy" (28.3%). In addition, 'adult men refuse to answer' (24.1%) was cited as the most common patient-related barrier. CONCLUSIONS: This study provided useful insights into the challenges encountered by the public healthcare providers when implementing a national screening program for men. The screening tool for adult men should be revised to make it more user-friendly. Further studies should explore the reasons why men were reluctant to participate in health screenings, thus enhancing the implementation of screening programs in primary care.

Effects of thermal boundary condition on methane oxidation in landfill cover soil at different ambient temperatures.

Microbial aerobic methane oxidation (MAMO) has been considered as an environmental-friendly method for mitigating methane emission from municipal landfill sites. Soil column has in a landfill cover under one-dimensional (1-D) condition. However, most of the published soil column tests failed to simulate 1-D heat transfer due to the use of thermal conductive boundary at the sidewall. In the present study, a heavily instrumented soil column was developed to quantify the effects of thermal boundary condition on the methane oxidation efficiency under different ambient temperatures in landfill cover soil. The sidewall of the soil column was thermally insulated to ensure 1-D heat transport as would have been typically expected in the field condition. Two soil column tests with and without thermal insulation were conducted at a range of controlled ambient temperatures from 15 to 30°C, for studying how soil moisture, matric suction, gas pressure, soil temperature and gas concentration evolve with MAMO. The test results reveal that ignoring thermal insulation in a soil column test would result in a greater loss of soil heat generation by MAMO and hence oxidation efficiency by up to 100% for the range of temperature considered. When the ambient temperature increased to 30°C (but less than the optimum temperature for MAMO), the MAMO efficiency increased abruptly at first but then decreased substantially with time, and this is likely due to the accumulation of biomass generated by MAMO.

A steady-state analytical profile method for determining methane oxidation in landfill cover.

Gas concentration profiles of carbon dioxide (CO2), oxygen (O2), methane (CH4) and nitrogen (N2) are usually measured during tests investigating microbial aerobic methane oxidation in landfill cover. However, only qualitative/limited information can be obtained from gas concentration profiles by existing methods. A new method is proposed to determine methane oxidation in soil quantitatively and comprehensively, including methane oxidation efficiency, stoichiometry, gas transfer mechanism, methane generation rate and gas reaction rate distributions. Governing equations are established based on mass balance for O2, CO2, CH4 and N2 at one-dimensional and steady-state condition. Gas transfer mechanisms considered include gas diffusion, advection and gas reaction. The method utilizes gas concentration profiles to determine gas diffusion for each gas component according to Fick's law. Then gas advections and reactions can be determined by mass balance. The method is validated by (i) published soil column tests investigating methane oxidation and (ii) a calibrated numerical model based on a selected soil column test. The new method is capable of determining methane oxidation efficiency, stoichiometry, gas transfer mechanism, methane generation rate and gas reaction rate distributions for CH4, CO2 and O2.

Theoretical analysis of coupled effects of microbe and root architecture on methane oxidation in vegetated landfill covers.

Reduction of soil moisture by plant root-water uptake could improve soil aeration for microbial aerobic methane oxidation (MAMO) in a landfill cover, but excessive soil moisture removal could suppress microbial activity due to water shortage. Existing models ignore the coupled microbe-vegetation interaction. It is thus not known whether the presence of plants is beneficial or adverse to MAMO. This study proposes a newly-improved theoretical model that couples the effects of root-water uptake and microbial activity for capturing water-gas flow and MAMO in unsaturated soils. Parametric studies are conducted to investigate the effects of root characteristics and transpiration rate on MAMO efficiency. Uniform, parabolic, exponential and triangular root architectures are considered. Ignoring the effects of water shortage on microbe over-predicts the MAMO efficiency significantly, especially for plants with traits that give high root-water uptake ability (i.e., uniformly-rooted and long root length). The effects of plants on MAMO efficiency depends on the initial soil moisture strongly. If the soil is too dry (i.e., close to the permanent wilting point), plant-water uptake, with any root architecture considered, would reduce MAMO efficiency as further soil water removal by plants suppresses microbial activity. Plants with exponential or triangular root architectures could preserve 10% higher MAMO than the other two cases. These two architectures are more capable of minimizing the adverse effects of root-water uptake due to microbial water shortage. This implies that high-water-demand plants such as those with long root length and with uniform or parabolic root architectures require more frequent irrigation to prevent from excessive reduction of MAMO efficiency.

Numerical modelling of methane oxidation efficiency and coupled water-gas-heat reactive transfer in a sloping landfill cover.

Microbial aerobic methane oxidation in unsaturated landfill cover involves coupled water, gas and heat reactive transfer. The coupled process is complex and its influence on methane oxidation efficiency is not clear, especially in steep covers where spatial variations of water, gas and heat are significant. In this study, two-dimensional finite element numerical simulations were carried out to evaluate the performance of unsaturated sloping cover. The numerical model was calibrated using a set of flume model test data, and was then subsequently used for parametric study. A new method that considers transient changes of methane concentration during the estimation of the methane oxidation efficiency was proposed and compared against existing methods. It was found that a steeper cover had a lower oxidation efficiency due to enhanced downslope water flow, during which desaturation of soil promoted gas transport and hence landfill gas emission. This effect was magnified as the cover angle and landfill gas generation rate at the bottom of the cover increased. Assuming the steady-state methane concentration in a cover would result in a non-conservative overestimation of oxidation efficiency, especially when a steep cover was subjected to rainfall infiltration. By considering the transient methane concentration, the newly-modified method can give a more accurate oxidation efficiency.

Unusual presentation of severe dengue: Dengue maculopathy.

Dengue infection is epidemic but ocular complications of dengue are less reported. We report a case of dengueinfected patient with disturbing ocular symptoms. He was admitted for severe dengue. Subsequently, he presented with symptoms of bilateral central scotoma with metamorphosia. Fundus examination revealed cotton wool spots and flame-shaped haemorrhages at the macula, with dull foveal light reflex. He was diagnosed with bilateral dengue maculopathy. The patient was managed conservatively with surveillance. One week later, his eye symptoms improved and were resolved six months later. Early recognition and close monitoring remains the key to successful management and interventions are rarely needed.

Gas breakthrough and emission through unsaturated compacted clay in landfill final cover.

Determination of gas transport parameters in compacted clay plays a vital role for evaluating the effectiveness of soil barriers. The gas breakthrough pressure has been widely studied for saturated swelling clay buffer commonly used in high-level radioactive waste disposal facility where the generated gas pressure is very high (in the order of MPa). However, compacted clay in landfill cover is usually unsaturated and the generated landfill gas pressure is normally low (typically less than 10 kPa). Furthermore, effects of clay thickness and degree of saturation on gas breakthrough and emission rate in the context of unsaturated landfill cover has not been quantitatively investigated in previous studies. The feasibility of using unsaturated compacted clay as gas barrier in landfill covers is thus worthwhile to be explored over a wide range of landfill gas pressures under various degrees of saturation and clay thicknesses. In this study, to evaluate the effectiveness of unsaturated compacted clay to minimize gas emission, one-dimensional soil column tests were carried out on unsaturated compacted clay to determine gas breakthrough pressures at ultimate limit state (high pressure range) and gas emission rates at serviceability limit state (low pressure range). Various degrees of saturation and thicknesses of unsaturated clay sample were considered. Moreover, numerical simulations were carried out using a coupled gas-water flow finite element program (CODE-BRIGHT) to better understand the experimental results by extending the clay thickness and varying the degree of saturation to a broader range that is typical at different climate conditions. The results of experimental study and numerical simulation reveal that as the degree of saturation and thickness of clay increase, the gas breakthrough pressure increases but the gas emission rate decreases significantly. Under a gas pressure of 10 kPa (the upper bound limit of typical landfill gas pressure), a 0.6m or thicker compacted clay is able to prevent gas breakthrough at degree of saturation of 60% or above (in humid regions). Furthermore, to meet the limit of gas emission rate set by the Australian guideline, a 0.6m-thick clay layer may be sufficient even at low degree of saturation (i.e., 10% like in arid regions).

A fully coupled model for water-gas-heat reactive transport with methane oxidation in landfill covers.

Methane oxidation in landfill covers is a complex process involving water, gas and heat transfer as well as microbial oxidation. The coupled phenomena of microbial oxidation, water, gas, and heat transfer are not fully understood. In this study, a new model is developed that incorporates water-gas-heat coupled reactive transport in unsaturated soil with methane oxidation. Effects of microbial oxidation-generated water and heat are included. The model is calibrated using published data from a laboratory soil column test. Moreover, a series of parametric studies are carried out to investigate the influence of microbial oxidation-generated water and heat, initial water content on methane oxidation efficiency. Computed and measured results of gas concentration and methane oxidation rate are consistent. It is found that the coupling effects between water-gas-heat transfer and methane oxidation are significant. Ignoring microbial oxidation-generated water and heat can result in a significant difference in methane oxidation efficiency by 100%.

The association between risk factors and hypertension in perak, malaysia.

INTRODUCTION: Hypertension is a major public health problem in Malaysia. A survey was initiated to examine the association of modifiable and non-modifiable risk factors for hypertension in Perak, Malaysia. METHODS: A total of 2025 respondents aged 30 years and above were recruited using a multi-stage sampling method. Hypertension was defined as self-reported hypertension and/or average of two blood pressure readings at single occasion with SBP ≥ 140mmHg or DBP ≥ 90 mmHg. Body mass index (BMI) was defined using the Asian criteria and International Physical Activity Questionnaire (IPAQ) was used to evaluate physical activity. Body weight, height and blood pressure were obtained using standard procedures. Univariate analyses were conducted to examine the associations between risk factors and hypertension. Multiple logistic regression was used to examine each significant risk factor on hypertension after adjusted for confounders. RESULTS: In total, 1076 (54.9%) respondents were found to be hypertensive. Significant associations (p <0.001) with hypertension were noted for increasing age, low physical activity, obese BMI, no education background and positive family history of hypertension. After adjusting for age, sex, ethnicity, education background, family history, BMI, physical activity, smoking and diet, respondents who were obese and had positive family history had higher odds for hypertension (OR:2.34; 95% CI:1.84-3.17 and 1.96 (1.59-2.42) respectively. A significant increase (p <0.001) in risk for hypertension was noted for age. Those with moderate physical activities were 1.40 (1.04-1.78) times more of having hypertension than those active. Poor diet score and smoking were not significantly associated with increased risk for hypertension. CONCLUSION: In conclusion, modifiable risk factors such as BMI and physical activity are important risk factors to target in reducing the risk for hypertension.

Neural correlates of auditory recognition memory in primate lateral prefrontal cortex.

The neural underpinnings of working and recognition memory have traditionally been studied in the visual domain and these studies pinpoint the lateral prefrontal cortex (lPFC) as a primary region for visual memory processing (Miller et al., 1996; Ranganath et al., 2004; Kennerley and Wallis, 2009). Herein, we utilize single-unit recordings for the same region in monkeys (Macaca mulatta) but investigate a second modality examining auditory working and recognition memory during delayed matching-to-sample (DMS) performance. A large portion of neurons in the dorsal and ventral banks of the principal sulcus (area 46, 46/9) show DMS event-related activity to one or more of the following task events: auditory cues, memory delay, decision wait time, response, and/or reward portions. Approximately 50% of the neurons show evidence of auditory-evoked activity during the task and population activity demonstrated encoding of recognition memory in the form of match enhancement. However, neither robust nor sustained delay activity was observed. The neuronal responses during the auditory DMS task are similar in many respects to those found within the visual working memory domain, which supports the hypothesis that the lPFC, particularly area 46, functionally represents key pieces of information for recognition memory inclusive of decision-making, but regardless of modality.

Patient satisfaction in an observation unit: the Consumer Assessment of Health Providers and Systems Hospital Survey.

BACKGROUND: The growing demand for inpatient beds in Singapore has led Tan Tock Seng Hospital to set up an observation medicine unit where patients are monitored and discharged within a 24-h period. METHODS: Using the Consumer Assessment of Health Providers and Systems (CAHPS) Hospital Survey, this descriptive study examines the satisfaction levels of patients admitted into an observation unit, in particular the communication between patients and doctors and nurses. The anonymous surveys were either self-administered by the patients or by the research assistant or nurses. RESULTS: 271 patients completed the survey, with 96% of patients satisfied with the politeness (ie, treating them with courtesy and respect, listening carefully to them) of the medical staff. More highly educated patients were more satisfied with the communication between the doctors or nurses, compared with less educated patients (p<0.05). However, less educated patients gave a higher rating of their observation unit stay than more educated patients (p<0.05). CONCLUSION: With patient satisfaction becoming increasingly important as an indicator of the quality of care in the present healthcare environment, doctors and nurses should seek to improve their communication with their patients so as to ensure that patients are satisfied and receive quality care.

Oestrogens for preventing recurrent urinary tract infection in postmenopausal women.

BACKGROUND: Recurrent urinary tract infection (RUTI) is defined as three episodes of urinary tract infection (UTI) in the previous 12 months or two episodes in the last six months. The main factors associated with RUTI in postmenopausal women are vesical prolapse, cystocoele, post-voidal residue and urinary incontinence, all associated with a decrease in oestrogen. The use of oestrogens to prevent RUTI has been proposed. OBJECTIVES: To estimate the efficacy and safety of oral or vaginal oestrogens for preventing RUTI in postmenopausal women. SEARCH STRATEGY: We searched the Cochrane Renal Group's specialised register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (from 1950), EMBASE (from 1980), reference lists of articles without language restriction. Date of last search: February 2007. SELECTION CRITERIA: Randomised controlled trials (RCTs) in which postmenopausal women (more than 12 months since last menstrual period) diagnosed with RUTI received any type of oestrogen (oral , vaginal) versus placebo or any other intervention were included. DATA COLLECTION AND ANALYSIS: Authors extracted data and assessed quality. Statistical analyses were performed using the random effects model and the results expressed as relative risk (RR) for dichotomous outcomes or mean difference (WMD) for continuous data with 95% confidence intervals (CI). MAIN RESULTS: Nine studies (3345 women) were included. Oral oestrogens did not reduce UTI compared to placebo (4 studies, 2798 women: RR 1.08, 95% CI 0.88 to 1.33). Vaginal oestrogens versus placebo reduced the number of women with UTIs in two small studies using different application methods. The RR for one was 0.25 (95% CI 0.13 to 0.50) and 0.64 (95% CI 0.47 to 0.86) in the second. Two studies compared oral antibiotics versus vaginal oestrogens (cream (1), pessaries (1)). There was very significant heterogeneity and the results could not be pooled. Vaginal cream reduced the proportion of UTIs compared to antibiotics in one study and in the second study antibiotics were superior to vaginal pessaries. Adverse events for vaginal oestrogens were breast tenderness, vaginal bleeding or spotting, nonphysiologic discharge, vaginal irritation, burning and itching. AUTHORS' CONCLUSIONS: Based on only two studies comparing vaginal oestrogens to placebo, vaginal oestrogens reduced the number of UTIs in postmenopausal women with RUTI, however this varied according to the type of oestrogen used and the treatment duration.

Hyperkalaemia in a patient with Graves' disease.

A case of hyporeninaemic hypoaldosteronism in a young girl with treated Graves' disease presenting as hyperkalaemia is described. The possible autoimmune link of these two conditions is discussed.

Release of paclitaxel from polylactide-co-glycolide (PLGA) microparticles and discs under irradiation.

Paclitaxel is a promising anti-cancer drug as well as a radiosensitizer for chemotherapy and radiotherapy applications. Because of the poor solubility of paclitaxel in water and most pharmaceutical reagents, it is usually formulated with an adjuvant called Cremophor EL, which causes severe side effects. This work develops new dosage forms of paclitaxel for controlled release application, which do not require the adjuvant and, thus, can avoid its associated side effects. Paclitaxel was encapsulated into the PLGA matrix with various additives such as polyethylene glycol (PEG), isopropyl myristate (IPM) and d-alpha tocopheryl polyethylene glycol (Vitamin E TPGS). These additives were used to enhance the release rate of paclitaxel from the polymer matrix. Spray-drying and an hydraulic press were used to prepare paclitaxel-PLGA microspheres and discs. The microspheres and discs were given different irradiation doses to investigate their effects on the surface morphology (characterized by SEM, AFM and XPS) and in vitro release properties. There seems to be a small effect of the ionizing radiation on various formulations. Although the irradiation did not cause observable changes on the morphology of the polymer matrix, the release rate can be enhanced by a few per cent. It was found that PEG has the highest enhancement effect for release rate among all the additives investigated in this study.

Identification and quantification of base and nucleoside markers in extracts of Ganoderma lucidum, Ganoderma japonicum and Ganoderma capsules by micellar electrokinetic chromatography.

The present paper describes the development of a micellar electrokinetic chromatographic method for the determination of nucleoside (adenosine, uridine) and base (uracil) markers in aqueous extracts of Ganoderma medicinal preparations. The markers were successfully separated within 10 min using an 80 mM borate buffer, with 25 mM sodium dodecyl sulfate adjusted to pH 9.0, an operating voltage of 22 kV, temperature of 20 degrees C and a hydrodynamic injection time of 5 s. Separations were carried out in a fused-silica capillary with peak detection by direct UV at 254 nm. Following semi-validation of the method, with each analyte showing a good linear relationship over a 0.2 to 20 ppm concentration range (correlation coefficients from 0.9986 to 0.9998), the amounts of the three markers in the various forms of Ganoderma were easily determined using a relatively simple extraction procedure.

Cryptococcal meningitis resulting in irreversible visual impairment in AIDS patients--a report of two cases.

Cryptococcus neoformans is the leading cause of meningitis in patients with Acquired Immune Deficiency Syndrome (AIDS) and is associated with high mortality rate. Presenting symptoms include fever, nausea and vomiting, altered mentation, headache and meningismus. Cryptococcal meningitis is not infrequently complicated by raised intracranial pressure and visual sequelae (sometimes by blindness). In patients who survive the infection, the most debilitating outcome appears to be visual impairment or blindness. Management of impending visual complication combines medical and surgical treatment modalities. We report two cases of cryptococcal meningitis associated with visual impairment.