Ultrasensitive detection of low-ppm H2S gases based on palladium-doped porous silicon sensors

In this study, the sensing properties of palladium-doped porous silicon (Pd/p-Si) substrates for low-ppm level detection of toxic H₂S gas are investigated. A Si substrate with dead-end pores ranging from nano- to macroscale was generated by a combined process of metal-assisted chemical etching (MacE) and electrochemical etching with tuned reaction time, in which nano-Pd catalysts were decorated by E-beam sputtering deposition. The sensing properties of the Pd/p-Si were enhanced as the thickness of the substrate layer increased; along with the resulting variation in surface area, this resulted in superior H₂S sensing performances in the low-ppm range (less than 3 ppm), with a detection limit of 300 ppb (sensitivity 30%) at room temperature. Furthermore, the sensor displayed excellent selectivity toward the hazardous H₂S molecules in comparison with various other reducing gases, including NO₂, CO₂, NH₃, and H₂, showing its potential for application in workplaces or environments affected by other toxic gases. The enhancement in sensing performance was possibly due to the increased dispersion and surface area of Pd nano-catalysts, which led to an increase in chemisorption sites of adsorbate molecules.

In this study, the sensing properties of palladium-doped porous silicon (Pd/p-Si) substrates for low-ppm level detection of toxic H₂S gas are investigated.     

梅毒血清固定患者血清IL-10和IL-12水平及相关性分析

目的:通过检测正常人群、梅毒未治疗患者、梅毒治疗后非梅毒螺旋体抗原血清试验转阴患者和梅毒血清固定患者血清IL-10、IL-12水平,并对梅毒血清固定患者血清IL-10和IL-12作相关性分析。以探讨细胞免疫与梅毒血清固定的关系,为有效治疗梅毒血清固定患者提供一定的理论依据。方法:采用双抗体夹心ELISA法分别检测正常人群组、梅毒未治疗组、梅毒治疗转阴组和梅毒血清固定组的IL-10和IL-12水平,将各组IL-10和IL-12水平行统计学分析。对梅毒血清固定组中IL-10与IL-12作相关性分析。结果:梅毒血清固定组患者IL-10水平显著高于正常对照组(P<0.01)、治疗后阴转组(P<0.01)及梅毒未治疗组(P<0.05);梅毒血清固定组患者IL-12水平与正常对照组、治疗后阴转组及梅毒未治疗组之间差异无显著性(P>0.05);梅毒血清固定组患者IL-10与IL-12水平之间无明显相关性(r=0.417,P>0.05)。结论:梅毒血清固定组患者机体内细胞免疫受到一定程度的抑制,发生了免疫不平衡,这种免疫抑制和不平衡可能造成了梅毒螺旋体能够逃脱机体的免疫监视而残存,成为引起血清固定的原因之一。     

'Moffett's' solution: a review of the evidence and scientific basis for the topical preparation of the nose

General anaesthesia, often causes a widespread vasodilation, producing a hyperaemic nasal mucosa, hence the need for a topical application to decongest the nose and reduce the nasal blood flow to optimize the operative field. The use of a combination of cocaine, sodium bicarbonate and adrenaline given the eponymous title of 'Moffett's Solution' is standard practice in many rhinological procedures to provide local anaesthesia, vasoconstriction and decongestion. We discuss each component of 'Moffett's' reviewing the science and evidence behind its usage and the huge variation in the techniques of its application.     

Functional assessment of the paediatric laryngeal airway

After resolution of conditions necessitating tracheostomy in children, decannulation may be extremely difficult and associated with significant morbidity. Endoscopy and radiography can identify anatomical abnormalities preventing decannulation. Physiological abnormalities are, however, more difficult to assess. A system has been developed whereby functional upper airway resistance can be calculated in children with a tracheostomy. The instrument used was a modified Mercury Electronics rhinomanometer. A probe was placed through the tracheostome and another probe was situated in an occluding anaesthetic face mask. Upper airway resistance was derived from the differential pressure and flow changes recorded in anaesthetized children who were breathing spontaneously. Studies in 26 children have revealed low airway resistance in all those successfully decannulated. Further studies will hopefully allow identification in advance of children who will have decannulation difficulties.     

The effectiveness of cardiopulmonary resuscitation instruction: animation versus dispatcher through a cellular phone

INTRODUCTION: We developed a cardiopulmonary resuscitation (CPR) instruction programme using motion capture animation integrated into cellular phones. We compared the effectiveness of animation-assisted CPR instruction with dispatcher-assisted instruction in participants with no previous CPR training. METHODS: This study was a single blind cluster randomized trial. Participants were allocated to either animation-assisted CPR (AA-CPR; 8 clusters, 44 participants) group or dispatcher-assisted CPR (DA-CPR; 8 clusters, 41 participants). The overall performance and time of each step of CPR cycle were recorded on a checklist by 3 assessors. The objective performances were evaluated using the Resusci Anne SkillReporter Manikin. Differences between the groups were compared using an independent t-test adjusted for the effect of clustering. RESULTS: The AA-CPR group had a significantly better checklist score (p<0.001) and time to completion of 1 CPR cycle (p<0.001) than the DA-CPR group. In an objective assessment of psychomotor skill, the AA-CPR group demonstrated more accurate hand positioning (68.8+/-3.6%, p=0.033) and compression rate (72.4+/-3.7%, p=0.015) than DA-CPR group. However, the accuracy of compression depth (p=0.400), ventilation volume (p=0.977) and flow rate (p=0.627) were below 30% in both groups. CONCLUSION: Audiovisual animated CPR instruction through a cellular phone resulted in better scores in checklist assessment and time interval compliance in participants without CPR skill compared to those who received CPR instructions from a dispatcher; however, the accuracy of important psychomotor skill measures was unsatisfactory in both groups.     

Subglottic haemangioma in children

Our experience with the treatment of 23 cases of subglottic haemangioma in children at the Hospital for Sick Children is presented. Different modalities of treatment are mentioned, with particular emphasis on excision with laryngo-tracheoplasty and the use of CO2 surgical laser. In a self-limiting lesion, our present policy is to use the CO2 laser to accelerate the rate of regression while minimizing morbidity and mortality.     

Neonatal Systemic AAV Induces Tolerance to CNS Gene Therapy in MPS I Dogs and Nonhuman Primates

The potential host immune response to a nonself protein poses a fundamental challenge for gene therapies targeting recessive diseases. We demonstrate in both dogs and nonhuman primates that liver-directed gene transfer using an adeno-associated virus (AAV) vector in neonates induces a persistent state of immunological tolerance to the transgene product, substantially improving the efficacy of subsequent vector administration targeting the central nervous system (CNS). We applied this approach to a canine model of mucopolysaccharidosis type I (MPS I), a progressive neuropathic lysosomal storage disease caused by deficient activity of the enzyme α-l-iduronidase (IDUA). MPS I dogs treated systemically in the first week of life with a vector expressing canine IDUA did not develop antibodies against the enzyme and exhibited robust expression in the CNS upon intrathecal AAV delivery at 1 month of age, resulting in complete correction of brain storage lesions. Newborn rhesus monkeys treated systemically with AAV vector expressing human IDUA developed tolerance to the transgene, resulting in high cerebrospinal fluid (CSF) IDUA expression and no antibody induction after subsequent CNS gene therapy. These findings suggest that inducing tolerance to the transgene product during a critical period in immunological development can improve the efficacy and safety of gene therapy.