Analysis of the Cicatricial Acceleration Method (MAC®) in Skin Repair in Wistar Rattus norvegicus with Induced Chemical Burns

Introduction: The cicatricial acceleration method (MAC®) promotes photobiological effects of an anti-inflammatory and healing nature. Its therapeutic radiation is emitted, producing photobiostimulant effects that result in rapid tissue repair and better tissue quality. The treatment of burns has always been a challenge, which involves both performing surgery and controlling and guiding scar regeneration, avoiding possible morbidities. Objective: To evaluate the effects of applying the MAC methodology with an AlGa (aluminum, gallium arsenide) laser on the time and quality of tissue repair in the skin of rats after induced chemical burns. Method: 22 adult male rats were subjected to a second-degree chemical burn on the back using 50% trichloroacetic acid. After the burns, the animals were randomly separated into 2 groups: control and experimental. The control group (G1) received placebo laser therapy and the laser group (G2) underwent laser irradiation with an energy density of 100 J/cm2. Histological analysis and macroscopic evaluation were carried out by means of the paper template method. Results: Group G1 showed (53%) of the necrosis area and group G2 showed (11%) necrosis area. Conclusion: The cicatricial acceleration method (MAC®) favored the repair of wounds caused by a 2nd-degree chemical burn, optimizing time and improving quality.

A Rational Design of Metal–Organic Framework Nanozyme with High‑Performance Copper Active Centers for Alleviating Chemical Corneal Burns

Metal–organic frameworks(MOFs)have attracted significant research interest in biomimetic catalysis.However,the modulation of the activity of MOFs by precisely tuning the coordination of metal nodes is still a significant challenge.Inspired by metalloenzymes with well-defined coordination structures,a series of MOFs containing halogen-coordinated copper nodes(Cu-X MOFs,X=Cl,Br,I)are employed to elucidate their structure–activity relationship.Intriguingly,experimental and theoretical results strongly support that precisely tuning the coordination of halogen atoms directly regulates the enzyme-like activities of Cu-X MOFs by influencing the spatial configuration and electronic structure of the Cu active center.The optimal Cu–Cl MOF exhibits excellent superoxide dismutase-like activity with a specific activity one order of magnitude higher than the reported Cu-based nanozymes.More importantly,by performing enzyme-mimicking catalysis,the Cu–Cl MOF nanozyme can significantly scavenge reactive oxygen species and alleviate oxidative stress,thus effectively relieving ocular chemical burns.Mechanistically,the antioxidant and antiapoptotic properties of Cu–Cl MOF are achieved by regulating the NRF2 and JNK or P38 MAPK pathways.Our work provides a novel way to refine MOF nanozymes by directly engineering the coordination microenvironment and,more significantly,demonstrating their potential therapeutic effect in ophthalmic disease.

Decreasing incidence of cutaneous chemical burns in a resource limited burn centre: is this a positive effect of modernization?

Background: Burns present a devastating injury to patients. Burns caused by chemical agents, present a worse scenario. In a resource limited country like Nigeria, readily available sources of these corrosive agents are mainly from lead-acid battery vendors and to some extent local small scale soap manufacturers who use caustic soda. We hypothesized that with the reduction in small scale soap manufacturing and increasing trend towards modernization in the use of dry cell batteries, chemical burns may be on the decline, and we sought to investigate this. Methods: The records of all acute burn patients seen at the Burns and Plastic Department of the National Orthopaedic Hospital Enugu Nigeria between January 2011 and December 2014 were retrospectively reviewed. The results were compared to similar studies carried out at the same centre. A questionnaire was administered to corrosive chemical (sulphuric and caustic soda) vendors to assess the trends in product sales and use in recent times. Results: A total of 624 acute burn cases were treated during the period;among which, 12 cases (1.9%) were chemical burns. When compared with previous studies at the centre, Chemical burn cases were recorded as the lowest rate. The median age of patients was 24 years. There were eight males and four females. Interpersonal assault was the commonest mechanism of injury with sulphuric acid suspected to be the commonest agent in 83.3% of the cases, while 16.7% of the cases were from accidental use of caustic soda. The head and neck as well as the upper limbs were the most affected (30%). Twenty-six questionnaires to lead-acid vendors were analyzed and revealed that all respondents noticed a marked downward trend in the sale of either sulphuric acid or caustic soda, and they attributed this to the ready availability of imported alternatives to locally manufactured soap or wet lead-acid batteries. Ease of use, durability and convenience of the dry cell batteries were cited as principal reasons. Conclusion: There appears to be a downward trend in the prevalence of chemical burns in our study compared to previous studies in the centre which may be due to reduced availability and access of corrosive chemicals to the general public. Further prospective multicentre studies to confirm this are recommended.

Burning surface formation mechanism of laser-controlled 5-aminotetrazole propellant

As an innovative propulsion technique, combustion mechanism of laser-augmented chemical propulsion has still to be ascertained. Benefiting from high nitrogen content and thermal stability, 5-aminotetrazole is a suitable ingredient for LACP. Under a flowing nitrogen environment, two kinds of unique burning surfaces were observed to occur for 5-ATZ, used as a single reacting propellant ingredient with the addition of carbon, under laser ablation. Both surfaces are hollow structures and differ by the possible presence of edges. Using micro computed tomography, the 3D perspective structures of both surfaces were revealed. Resorting to various characterization methods, a unified formation mechanism for both surfaces is proposed. This mechanism specifically applies to laser ablation, but could be crucial to common burning mechanisms in LACP.

Application of transient burning rate model of solid propellant in electrothermal-chemical launch simulation

A 30 mm electrothermal-chemical(ETC) gun experimental system is employed to research the burning rate characteristics of 4/7 high-nitrogen solid propellant. Enhanced gas generation rates(EGGR) of propellants during and after electrical discharges are verified in the experiments. A modified 0D internal ballistic model is established to simulate the ETC launch. According to the measured pressure and electrical parameters, a transient burning rate law including the influence of EGGR coefficient by electric power and pressure gradient(dp/dt) is added into the model. The EGGR coefficient of 4/7 high-nitrogen solid propellant is equal to 0.005 MW-1. Both simulated breech pressure and projectile muzzle velocity accord with the experimental results well. Compared with Woodley's modified burning rate law, the breech pressure curves acquired by the transient burning rate law are more consistent with test results. Based on the parameters calculated in the model, the relationship among propellant burning rate, pressure gradient(dp/dt) and electric power is analyzed. Depending on the transient burning rate law and experimental data, the burning of solid propellant under the condition of plasma is described more accurately.

Microstructure Analysis for Chemical Interaction between Cesium and SUS316 Steel in Fast Breeder Reactor Application

The objective of this study is to presume cesium corrosion process and its dominant factors in SUS316 steel, a fuel cladding material for fast breeder reactor application, based on both experimental results of cesium corrosion out-pile test and thermodynamic consideration. The cesium corrosion test was performed in simulated environment of high burn-up fuel pin. And main corrosion products in the specimen after the corrosion test were specified by TEM （transition electron microscopy） and SEM （scanning electron microscopy） in order to formulate a hypothesis of the cesium corrosion process. At the end of this study, it was found that the dominant factors of the corrosion process are the amount of cesium on the surface of the specimen, chromium content in the alloy, the supply rate of oxygen and temperature.

Inhibitory effect of polysulfated heparin endostatin on alkali burn induced corneal neovascularization in rabbits

AIM: To investigate anti-angiogenic effects of polysulfated heparin endostatin(PSH-ES) on alkali burn induced corneal neovascularization(NV) in rabbits.METHODS: An alkali burn was made on rabbit corneas to induce corneal NV in the right eye of 24 rabbits. One day after burn creation, a 0.2 m L subconjunctival injection of 50 μg/m L PSH-ES, 50 μg/m L recombinant endostatin(ES), or normal saline was administered every other day for a total of 14d(7 injections). Histology and immunohistochemisty were used to examine corneas.Corneal NV growth was evaluated as microvessel quantity and corneal vascular endothelial growth factor(VEGF)expression was measured by immunohistochemical assay.RESULTS: Subconjunctival injection of ES and PSHES resulted in significant corneal NV suppression, but PSH-ES had a more powerful anti-angiogenic effect than ES. Mean VEGF concentration in PSH-ES treated corneas was significantly lower than in ES treated and saline treated corneas. Histological examination showed that corneas treated with either PSH-ES or ES had significantly fewer microvessels than eyes treated with saline. Additionally corneas treated with PSH-ES had significantly fewer microvessels than corneas treated with ES.CONCLUSION: Both PSH-ES and recombinant ES effectively inhibit corneal NV induced by alkali burn.However, PSH-ES is a more powerful anti-angiogenic agent than ES. This research has the potential to provide a new treatment option for preventing and treating corneal NV.

Paediatric burns secondary to nail adhesives: a case series

Background:Nail adhesives are widely available beauty products that are used in the cosmetic industry and households to attach false nails.Nail adhesive burns are uncommon,and it is crucial that healthcare providers and the public are aware of its potential to cause chemical burn.Case Presentation:Case series of accidental burns secondary to cyanoacrylate nail glue treated at the Welsh Centre for Burns and Plastic Surgery(WCBPS)in Swansea,United Kingdom.Conclusion:All of the burns were observed in children and occurred due to accidental spillage.Therefore,it is important for the public to be aware that nail glue is a chemical agent which should be stored safely away from the reaches of young children.The case series highlights the importance of first aid in reducing the severity of chemical burns secondary to the nail adhesives,and its early recognition and treatment are emphasised.

Serious Burn by Sulfuric Acid: Case Report of Particular Therapeutic Strategy in a Non-Specialized ICU at Hôpital Principal de Dakar (HPD) Sénégal

Managing severe burns remains problematic due to the lack of specialized units, but also because of the delay in implementing emergency care. The aim is to show that an adapted strategy, can lead to satisfying management of chemical burns. The authors report retrospectively the case of a patient admitted for chemical burns, and treated in a non-specialized intensive care unit;a 38 years old male, referred for burns by sulfuric acid at his workplace. On admission to H15, the clinic did not reveal any vital organs failure. Burns were localized on two legs and soles of the two feet (18% TBSA). Treatment combined daily dressings with silver sulfadiazine. On day 14, the wound healing associated occlusive gauze dressing, iodine cream application, and mechanical debridement. On day 47, a 5% dermal autograft performed on right foot favored with good attachment grafts. On day 58, the patient was released after complete skin recovery. Then, in a non-specialized burn unit and without early surgery access, our wound healing adapted strategy was successful. In Senegal, chemical burns represent about 2.5% of burn cases. They are often from accidents on occupation job, while generally in Africa chemical burns result from criminal attacks. Patients with severe lesions are admitted in non-specialized environments after an extended time of transfer, and don’t have efficient initial care. This may explain the high morbidity and mortality after burns in our country. The lack of surgical facilities such as skin substitutes, in non-specialized unit on low or median income countries (LMICs), explains this long period of wound healing. The treatment of severe burn in LMICs is hazardous.

Physical and chemical effects of phosphorus-containing compounds on laminar premixed flame

Phosphorus-containing compounds are the promising halon alternatives for flame inhibitions. However, some literatures suggested that the phosphorus-related inhibitors may behave as the unfavorable ones that will increase the burning velocity under lean-burn conditions, and this indeed posed potential threats to the fire prevention and fighting. To seek deeper insights into the reaction process, a numerical investigation was actualized to study the phosphorus-related effects on methane-air flames. By replacing a phosphorus-related inhibitor with the corresponding decomposed molecules, the detailed promoting and inhibiting effects of combustion were separated from the general chemical effect. A comparative study was carried out to identify the interaction between the two effects under different combustion conditions. It is observed that the promoting effect becomes the dominant factor during the reaction process when the equivalence ratio is smaller than 0.60. In this lean-burn condition, the exothermic reactions were faster than the others within the reaction chains due to the reduction of radical recombination in hydrocarbon oxidation. The results are believed to be useful for the further application and improvement of flame inhibitors.

光刻与化学机械抛光技术原位集成制备SU-8微透镜阵列

垂直腔面发射激光器通常与微光学元件组合使用,以改善激光束的聚焦或准直效果。研究了一种光刻和化学机械抛光技术相结合的新工艺方法,用于原位制备SU-8微透镜阵列。通过调控光刻参数,可以精确控制微透镜的直径与高度。实验制备了不同尺寸的SU-8微透镜阵列,它们具有光滑的表面,分辨率可达12.7 lp/mm,展示出良好的光学特性与高稳定性。这是一种低成本和高良率的微透镜制备方法,适用于在已成型的垂直腔面发射激光器表面原位集成制备高精度定位的微透镜,无需额外的光学对准、转移和键合步骤。

Chemical Characterization of PM10 Particulate Matter in the Ambient Air of a Region of Central Italy (Umbria)

Atmospheric particulate matter is a critical factor for many regional urban areas of Umbria (Central Italy region). During 2013 the monitoring air quality network, managed by ARPA Umbria, has been upgraded to Legislative Decree of 13 August 2010, n.155 and an analytical study about chemical composition of PM10 (Particulate Matter with diameter of 10 micrometres or less) over all the region has been started. The PM10 filters have been analyzed for Benzo(α)Pyrene, Pb, Cr, Ni and Cd to check compliance with limits or target values defined in Italian regulation (Legislative Decree of 13 August 2010, n.155);other parameters, like US-EPA list Polycyclic Aromatic Hydrocarbons (PAHs), Polychlorinated Dibenzo-p-Dioxins and Polychlorinated Dibenzo Furans (PCDD/ Fs), Polychlorinated Biphenyls (PCBs), Organic Carbon/Elemental Carbon (OC/EC) and Levoglucosan were analyzed because they are toxic or because they identify particular pollutant sources. The data obtained showed a large and diffusive biomass burning contribution, widely used in the Umbria Region both for domestic heating in traditional fireplaces and for combustion of pruning residues. In particular the urban sites of Terni and suburban site near Terni (Narni), both lying in the Terni basin called “Conca Ternana”, showed a chemical composition of PM10 that suggests a very large anthropization. This area is the principal industrial reality in the Central Italy because there is a steel production plant, a Municipal solid waste (MSW) burning plant and a chemical plant.

Burning rate analysis of laser controlled 5-aminotetrazole propellant

As an innovative propulsion technique, laser augmented chemical propulsion(LACP) seems superior to the traditional ones. However, the corresponding combustion theories have still to be ascertained for LACP. Burning rate of 5-aminotetrazole(5-ATZ) propellant has been studied by testing pressed samples under different combustor pressures and laser powers. Based on micro computed tomography(Micro CT),an advanced thickness-over-time(TOT) method to characterize the regression of the produced nonplanar burning surface is established. Because of a shell structure covering the combustion surface,the burning rate of the implemented 5-ATZ propellant is not constant during laser ablation. Resorting to functional fitting, a new law of non-constant burning including the effect of the observed unique burning surface structures is proposed. Accordingly, applicable combustion conditions of 5-ATZ based propellants have been preliminarily speculated for future research activities.

常见化学烧伤的救治方法

随着新化工产品的不断涌现,化学烧伤在工作中发生率明显升高,化学烧伤的损伤一般发生在工作环境中,严重程度和化学品的性质、剂量、浓度、接触时间和接触面积、急救措施等有着密切的关系。目前较多医疗机构内缺乏化学烧伤救治的标准操作流程,本文通过介绍常见局部化学烧伤的处理的基本原则,为临床治疗提供参考。

老年中重度烧伤患者切痂植皮术中使用右美托咪定联合咪达唑仑的麻醉效果

【目的】探讨老年中重度烧伤患者切痂植皮术中使用右美托咪定(Dex)联合咪达唑仑的麻醉效果。【方法】102例老年中重度烧伤患者,随机分为观察组和对照组,每组51例。对照组采用丙泊酚维持麻醉,观察组采用Dex联合咪达唑仑维持麻醉。比较两组术中及术后不同时间点的心率(HR)、平均动脉压(MAP)水平;比较两组患者手术情况及手术前后血浆皮质醇(COR)、肾上腺素(E)、去甲肾上腺素(NE)水平;比较两组患者术后疼痛[视觉模拟评分法(VAS)]、镇静效果(Ramsay镇静评分)、躁动发生率及不良反应发生情况。【结果】观察组手术结束时、拔管前及拔管后30 min HR均低于对照组(P<0.05),MAP均高于对照组(P<0.05)。术后30 min时,观察组血浆COR、E、NE水平均低于对照组(P<0.05)。观察组VAS评分低于对照组(P<0.05),Ramsay镇静评分高于对照组(P<0.05),躁动发生率低于对照组(P<0.05)。观察组的苏醒时间短于对照组(P<0.05),两组不良反应总发生率比较,差异无统计学意义(P>0.05)。【结论】Dex联合咪达唑仑应用在老年中重度烧伤患者切痂植皮术中,能有效减轻患者术后应激反应,稳定血流动力学,缩短苏醒时间,减少术后疼痛,降低躁动发生率,且安全性较好。

火烧迹地恢复后不同稳定机制土壤有机碳库特征研究

以大兴安岭重度火烧迹地经过不同方式恢复的林分土壤为研究对象,采用物理-化学联合分组方法,研究未保护、物理保护、化学保护、生物化学保护、物理-化学保护和物理-生物化学保护有机碳组分含量特征及其与土壤总有机碳含量间的关系。结果表明,1)人工恢复的林分土壤总有机碳、未保护有机碳、物理保护有机碳、物理-化学保护有机碳、物理-生物化学保护有机碳和生物化学保护有机碳含量均显著高于自然恢复。化学保护有机碳含量在不同恢复方式下变化不显著。除化学保护有机碳和物理-化学保护有机碳外,其余各保护态有机碳均表现为上层土壤含量显著高于下层(P<0.05)。2)2种恢复方式下的土壤有机碳组分均以未保护有机碳占比最高,物理-化学保护有机碳占比最低。与天然恢复相比,人工恢复下的土壤物理保护有机碳含量占比显著提高2.80%~3.19%(P<0.05)。3)回归分析表明,除物理-化学保护有机碳和化学保护有机碳组分外,其余各保护态有机碳组分与总有机碳含量之间均呈极显著的正相关关系(P<0.001)。大兴安岭重度火烧迹地经过32 a的人工恢复,更利于土壤总有机碳积累,土壤未保护有机碳的积累更多。研究结果为该区域重度火烧迹地植被恢复提供科学依据。

Beyond the burn: Studies on the physiological effects of flamethrowers during World War Ⅱ

Flamethrowers are widely considered one of warfare’s most controversial weapons and are capable of inflicting gruesome physical injuries and intense psychological trauma.Despite being the last of the major combatants in World WarⅡ(WWⅡ)to develop them,the U.S.military quickly became the most frequent and adept operator of portable flamethrowers.This gave the U.S.military ample opportunity to observe the effects of flamethrowers on enemy soldiers.However,while most people in modern times would consider immolation by flamethrower to be an unnecessarily painful and inhumane way to inflict casualties,immolation was,at one point during WWⅡ,referred to as"mercy killing"by the U.S.Chemical Warfare Service(CWS).This mischaracterization arose from a series of firsthand accounts describing what were believed to be quick,painless,and unmarred deaths,as well as from a poor and incomplete understanding of flamethrower lethality.As a result,indirect mechanisms such as hypoxia and carbon monoxide poisoning were generally absent from accounts of the flamethrower’s fatal effects.It was not until several years after flamethrowers were introduced to the frontlines that the CWS and National Defense Research Committee(NDRC)conducted a series of tests to better understand the physiological and toxicological effects of flamethrowers.This article examines how the initial absence of scientific data on the physiologic effects of flamethrowers led to an inaccurate understanding of their lethality,and bizarre claims that one of history’s most horrific instruments of war was considered one of the more"humane"weapons on the battlefield.

2023年春节期间宿迁市PM_(2.5)化学组分特征与来源解析

2023年春节期间(1月18日—25日),宿迁市发生了一次短时PM_(2.5)重度污染,利用宿迁市环境空气国控监测站、大气超级站、在线单颗粒气溶胶质谱仪等对PM_(2.5)化学组分进行分析,对颗粒物的主要组分进行来源解析,探讨燃放烟花爆竹对空气质量的影响。结果表明,春节期间整体空气质量良好,峰值出现在21日22时—22日0时(除夕夜),PM_(2.5)浓度范围为165~206μg/m^(3),达到重度污染水平,各项化学组分抬升明显,二次有机物占比明显抬升。烟花爆竹燃放指征重金属元素在除夕夜前后变化幅度较大,PM_(2.5)小时均值同步上升3.0倍,K^(+)和Cl^(-)浓度多次出现同时突升,重金属元素和离子元素双重佐证了烟花爆竹燃放助推了颗粒物浓度高值。由于烟花燃放特征离子与本地扬尘源特征离子存在共性(Al^(+)、Ba^(+)、Mg^(+)等矿物质成分),在不利气象条件下主要表现为扬尘源对大气颗粒物贡献率的增加。

A Review on Surface Stress-Based Miniaturized Piezoresistive SU-8 Polymeric Cantilever Sensors

In the last decade, microelectromechanical systems(MEMS) SU-8 polymeric cantilevers with piezoresistive readout combined with the advances in molecular recognition techniques have found versatile applications,especially in the field of chemical and biological sensing.Compared to conventional solid-state semiconductor-based piezoresistive cantilever sensors, SU-8 polymeric cantilevers have advantages in terms of better sensitivity along with reduced material and fabrication cost. In recent times,numerous researchers have investigated their potential as a sensing platform due to high performance-to-cost ratio of SU-8 polymer-based cantilever sensors. In this article, we critically review the design, fabrication, and performance aspects of surface stress-based piezoresistive SU-8 polymeric cantilever sensors. The evolution of surface stress-based piezoresistive cantilever sensors from solid-state semiconductor materials to polymers, especially SU-8 polymer, is discussed in detail. Theoretical principles of surface stress generation and their application in cantilever sensing technology are also devised. Variants of SU-8 polymeric cantilevers with different composition of materials in cantilever stacks are explained. Furthermore, the interdependence of the material selection, geometrical design parameters, and fabrication process of piezoresistive SU-8 polymeric cantilever sensors and their cumulative impact on the sensor response are also explained in detail.In addition to the design-, fabrication-, and performancerelated factors, this article also describes various challenges in engineering SU-8 polymeric cantilevers as a universal sensing platform such as temperature and moisture vulnerability. This review article would serve as a guideline for researchers to understand specifics and functionality of surface stress-based piezoresistive SU-8 cantilever sensors.

考虑化学反应强耦合的植被火焰条件下直流间隙多物理场耦合模型

为分析电场、温度场与燃烧化学反应的相互作用,更准确地模拟植被火焰条件下间隙带电粒子分布情况,建立了考虑化学反应强耦合的植被火焰条件下直流间隙多物理场耦合模型。并通过植被燃烧试验的结果对模型关键参数进行设置,利用模型仿真分析了不同极性电压、电极高度对带电粒子分布特性的影响及带电粒子对背景电场的影响。结果表明:该文试验条件下,松木热解反应方程系数修正为C_(10)H_(14)O_(6)→4C+3CO+CO_(2)+2CH_(4)+2H_(2)+H_(2)O、热解反应速率为2.4×10^(–8)mol/(m^(3)·s)时,仿真与试验结果最为接近;随着电极高度的降低,电极附近与电极极性相异的带电粒子浓度由10^(–9m)ol/m^(3)增加至10^(–8)mol/m^(3),变化趋势与泄漏电流相似;带电粒子对正电极附近初始背景电场的影响效果大于负极性,正电极附近背景电场的增幅为70%~110%,负电极附近则增大了40%~80%。