相对湿度对牛仔织物的血滴污染形成的影响
Houssine Benabdelhalim1, David Brutin1
1Aix Marseille Univ, CNRS, IUSTI, Marseille, France.
Forensic science international
|August 21, 2023
概括
这项研究表明,血滴对牛仔的影响如何取决于速度和湿度. 较高的湿度会导致,改变污点的大小和形状,这对于犯罪现场分析至关重要.
科学领域:
- 法医科学 法医科学 法医科学
- 流体动力学 流体动力学
- 织科学 织科学
背景情况:
- 了解血迹模式在法医调查中至关重要.
- 之前的研究还没有充分探讨环境因素的影响,如湿度对织物上血迹的形成.
研究的目的:
- 为了研究全人血液滴落在牛仔面料上的冲击动态.
- 分析撞击速度,相对湿度和基板间距对血迹特征的影响.
- 开发一个血迹区域的预测模型.
主要方法:
- 实验使用全人血滴 (直径3毫米,温度37°C) 冲击牛仔进行.
- 控制了不同冲击速度 (U0),相对湿度 (30%和70%) 和织物-基板间距 (S).
- 血迹的尺寸和动行为被仔细测量和分析.
主要成果:
- 在30%的相对湿度下,斑点面积随着撞击速度增加到3.3m/s,然后保持不变.
- 在70%的相对湿度下,血液恶性地落入织物中,使最终的染色区域独立于撞击速度.
- 随着撞击速度的增加,料对染色面积的贡献减少了.
结论:
- 相对湿度显著影响牛仔上血迹的形成和特征.
- 这些发现强调了在法医血迹模式分析中考虑环境条件的重要性.
- 提出了一个修改后的相关性来预测血迹面积,考虑到湿度的影响.
相关概念视频
Drying Shrinkage
100
When hardened concrete is exposed to air with a relative humidity of less than 100 percent, it begins to lose the free water within its capillaries. As this water evaporates, the water initially adsorbed onto the calcium silicate hydrates migrates towards these now empty spaces and eventually evaporates as well. Over time, as more water leaves, the volume of the concrete decreases, a phenomenon known as drying shrinkage.
A portion of this drying shrinkage can be reversed; if the concrete is...
A portion of this drying shrinkage can be reversed; if the concrete is...
100
Viscosity
5.9K
When water is poured into a glass, it falls freely and quickly, whereas if honey or maple syrup is poured over a pancake, it flows slowly and sticks to the surface of the container. This difference in the flow of different kinds of liquids arises due to the fluid friction between the liquid layers and the liquid and the surrounding material. This property of fluids is called fluid viscosity. In this example, water has a lower viscosity than honey and maple syrup.
The SI unit of viscosity is...
The SI unit of viscosity is...
5.9K
Vapor Pressure Lowering
26.9K
The equilibrium vapor pressure of a liquid is the pressure exerted by its gaseous phase when vaporization and condensation are occurring at equal rates:
Dissolving a nonvolatile substance in volatile liquid results in a lowering of the liquid’s vapor pressure. This phenomenon can be explained by considering the effect of added solute molecules on the liquid's vaporization and condensation processes. To vaporize, solvent molecules must be present at the surface of the solution....
Dissolving a nonvolatile substance in volatile liquid results in a lowering of the liquid’s vapor pressure. This phenomenon can be explained by considering the effect of added solute molecules on the liquid's vaporization and condensation processes. To vaporize, solvent molecules must be present at the surface of the solution....
26.9K
Surface Tension, Capillary Action, and Viscosity
28.1K
Surface Tension
The various IMFs between identical molecules of a substance are examples of cohesive forces. The molecules within a liquid are surrounded by other molecules and are attracted equally in all directions by the cohesive forces within the liquid. However, the molecules on the surface of a liquid are attracted only by about one-half as many molecules. Because of the unbalanced molecular attractions on the surface molecules, liquids contract to form a shape that minimizes the number...
The various IMFs between identical molecules of a substance are examples of cohesive forces. The molecules within a liquid are surrounded by other molecules and are attracted equally in all directions by the cohesive forces within the liquid. However, the molecules on the surface of a liquid are attracted only by about one-half as many molecules. Because of the unbalanced molecular attractions on the surface molecules, liquids contract to form a shape that minimizes the number...
28.1K
Precipitation Titration Curve: Analysis
1.1K
The precipitation titration curve demonstrates the change in concentration of one reactant with the volume of titrant added. During the titration of chloride ions with silver nitrate, the precipitation titration curve is divided into three regions: before, at, and after the equivalence point. Before the equivalence point, low redissolution of the sparingly soluble silver chloride precipitate gives a low silver ion concentration. However, in the second region, representing the equivalence point,...
1.1K
Clausius-Clapeyron Equation
57.1K
The equilibrium between a liquid and its vapor depends on the temperature of the system; a rise in temperature causes a corresponding rise in the vapor pressure of its liquid. The Clausius-Clapeyron equation gives the quantitative relation between a substance’s vapor pressure (P) and its temperature (T); it predicts the rate at which vapor pressure increases per unit increase in temperature.
57.1K


