Chemical Imaging of Human Fingermark by X‐ray Photoelectron Spectroscopy (XPS)

X-ray photoelectron spectroscopy (XPS) is a widely used technique to characterize the surface chemistry of materials. It plays a crucial role in accessing qualitative and quantitative information and in detecting the presence of chemical functional groups on the surface of any material. the forensic methods available to detect and identify elements and organic/inorganic compounds are often destructive, so evidence cannot be re-analyzed. However, XPS allows rapid analysis of samples without damaging them. Recently, an increasing number of forensic researchers have begun to study certain chemical information on fingermarks. in this study, the authors aimed to present the applicability and power of XPS imaging in fingermark analysis which can also provide specific information about the fingermark chemical composition. Herein, monochromated X-ray (Al K alpha) spot size was fixed at 50 mu m. XPS mapping resulted in the acquisition of spectra at each pixel, in an array of 41 x 30 pixels with a step size of 50 mu m. Then, a simple discussion has been made about how the scanned surface spectrum and basic snapshot spectra are used to identify different components at a fingertip of a scanned surface area (similar to 3 mm(2)). Hence, a fingermark pattern contaminated with caffeine, TiO2, and Pb/PbO deposited on the silicon wafer can be chemically mapped and visualized by XPS using principal component analysis (PCA). Thus, the present study showed the possible applicability of XPS for the identification of illicit drugs of abuse, gunshot residue, and skin care products on latent fingermark by mimicking a crime scene evidence

Visualization of Micro-Particle Retention on a Heterogeneous Surface Using Micro-models: Influence of Nanoscale Surface Roughness

Nanoscale surface roughness and charge heterogeneity have been widely recognized to influence particle retention in porous media under unfavourable chemical conditions such as solutions of low ionic strength (IS) or high pH. However, previous researches have not appreciated the influence of nanoscale surface roughness on particle retention under favourable chemical conditions (e.g. high solution IS). This information is needed to better understand and predict particle transport and retention in such natural environments, such as enhanced oil recovery in a high-salinity reservoir. A glass-etched micro-model was employed to directly visualize retention of micro-sized particles and their spatial distribution on the glass surface under various chemical conditions. The extended DLVO calculations accounting for the effect of nanoscale surface roughness on the interaction energies were employed to quantitatively evaluate the experimental results. It was shown that nanoscale roughness on solid surfaces significantly reduced the strength of primary minimum attachment when the solution IS was high. In particular, increasing the density of roughness on the solid surface increased the strength of primary minimum, whereas increasing the roughness height decreased the strength of primary minimum interaction. Consequently, retained particles in the primary minimum are expected to be susceptible to detachment via hydrodynamic drag forces and movement of air–water interfaces during transient in water saturation (e.g. drainage or imbibition). Indeed, results obtained from the micro-model experiments demonstrated that only a fraction of solid surface was available for particle retention even at a very high IS of 0.6 M.Joel Argent, Saeed Torkzaban, Stephen Hubbard, Helen Le, Tahmineh Amirianshoja, Manouchehr Haghigh

Cirurgia vídeolaparoscópica: precauções e recomendações

O desenvolvimento da cirurgia videolaparoscópica incentivou os cirurgiões a uma atualização para melhor compreensão das alterações fisiológicas provocadas pela utilização do pneumoperitônio com gás carbônico. É de grande relevância o conhecimento de tais alterações assim como também de medidas para evitar sua progressão para complicações de solução às vezes difícil. Embora a cirurgia laparoscópica tenha se difundido com mais intensidade a partir da década de 80, maior atenção tem sido dada às suas aplicações em um número crescente de procedimentos cirúrgicos, antes realizados exclusivamente pela via aberta, laparotômica ou convencional. No entanto, há necessidade de mais estudos e pesquisas para um melhor entendimento e manuseio de tais alterações. Os autores fazem uma revisão da literatura com enfoque nas alterações fisiológicas causadas pelo pneumoperitônio, nas condições que interferem nas indicações da videocirurgia, principais indicações atuais do método, suas limitações e complicações. Chamam a atenção para a ocorrência de complicações relacionadas com o treinamento deficiente