Alternative Light Source Research Articles

Integrating presumptive and confirmatory semen tests into DNA profiling of sexual assault evidence: a Philippine example

BackgroundIn sexual assault casework, the detection of semen on a sample supports an allegation of sexual contact and indicates the presence of DNA from a male source. Ideally, techniques employed should demonstrate high sensitivity and specificity and should be compatible with standard DNA typing procedures. To contribute recommendations for routine DNA tests of sexual assault cases in the Philippines, we evaluated the RSIDTM-Semen, an immunochromatographic test for human semenogelin (Sg), in parallel with the alternate light source (ALS) method using Mini BLUMAXX™ III and the acid phosphatase (AP) test using Seminal Fluid DISCHAPSTM.ResultsThe ALS detected semen diluted until 5% (v/v) fluid, whereas the AP assay was sensitive down to 0.5% (v/v). Non-blood-containing stains were visible under blue light except on dark-colored cloth. All semen-containing fluids including post-ejaculatory urine tested positive for AP and Sg. RSIDTM-Semen was sensitive down to 0.5 nL of semen; did not cross-react with blood, saliva, and female urine; and successfully detected Sg on the majority of post-coital samples tested. Complete short tandem repeat (STR) profiles of the semen donors were generated for most samples incubated in the RSIDTM-Universal Buffer (UB). However, we report an extraction efficiency of 15% for UB which can lead to partial profiles in already compromised samples.ConclusionWe recommend the use of ALS in visualizing stains present on surfaces and the AP test on blood-stained materials. These presumptive tests should be followed by RSIDTM-Semen test to confirm the presence of semen prior to DNA profiling.

Evaluation of a model of bruising in pigmented skin for investigating the potential for alternate light source illumination to enhance the appearance of bruises by photography of visible and infrared light.

The purpose of this study was to evaluate the ability of alternate light source illumination to enhance bruises in pigmented skin. Previous work was limited to simulating bruises in non-pigmented (Caucasoid type) skin by injecting blood into pigskin. In this study, it was investigated if adding a layer of melanin to the surface of the skin would simulate pigmented skin. The study included evaluating the use of a filter that transmitted infrared light (wavelength greater than 720nm) in place of the recommended visible light filters for the alternate light sources. The results obtained using pigskin with a layer of melanin were almost the same as results using the naturally pigmented goat ear. This indicated adding a layer of melanin could be used as a model for pigmented skin in this simulation of fresh bruising. Comparing the pigskin without melanin with pigskin with melanin revealed that the optimal light source to enhance the appearance of bruising, simulated by injection of blood, changed from violet to blue-green. Using the infrared transmitting filter resulted in greater enhancement than using the alternate light sources with their recommended visible light filter. The advantage of using the infrared transmitting filter was greater with the pigskin coated with melanin and the naturally pigmented goat ears than in the non-pigmented pigskin, however, the results remain to be validated using real bruises in naturally pigmented human skin.

Color-Tunablility in GaN LEDs Based on Atomic Emission Manipulation under Current Injection

The development of efficient electrically driven color-tunable solid-state light sources will enable new capabilities in lighting and display technologies. Although alternative light sources such a...

Light Emitting Diodes as Alternative Light Sources: Effects of Ultraviolet Frequencies on Microbial Replication

Hospital acquired infections (HIAs) are a major global problem as they increase morbidity, mortality, hospitalization length and the cost of care for hospitalized patients [1,2].

Effect on the longitudinal coherence properties of a pseudothermal light source as a function of source size and temporal coherence.

In the present Letter, a synthesized pseudothermal light source having high temporal coherence (TC) and low spatial coherence (SC) properties is used. The longitudinal coherence (LC) properties of the spatially extended monochromatic light source are systematically studied. The pseudothermal light source is generated from two different monochromatic laser sources: He-Ne (at 632nm) and DPSS (at 532nm). It was found that the LC length of such a light source becomes independent of the parent laser's TC length for a large source size. For the chosen lasers, the LC length becomes constant to about 30μm for a laser source size of ≥3.3 mm. Thus, by appropriately choosing the source size, any monochromatic laser light source depending on the biological window can be utilized to obtain high axial resolution in an optical coherence tomography (OCT) system irrespective of its TC length. The axial resolution of 650nm was obtained using a 1.2 numerical aperture objective lens at a 632nm wavelength. These findings pave the path for widespread penetration of pseudothermal light into existing OCT systems with enhanced performance. A pseudothermal light source with high TC and low SC properties could be an attractive alternative light source for achieving high axial resolution without needing dispersion compensation as compared to a broadband light source.

Comparison of dichroric with absorptive filters when using alternate light sources to enhance bruises

Background: Using alternate light sources requires a filter to block the illuminating source to allow fluoresced light (with longer wavelength) to be observed.1 Absorptive filters are dye based. Dichroic filters use thin-film interference. It was proposed their selectivity could be beneficial for use with alternate light sources.

Evaluation of models of dark skin for investigating the potential for alternate light sources to enhance bruises

Previous studies assessing the ability of alternate light sources to enhance the appearance of bruises used pigskin1 and cadavers.2 This limited the investigations to non-pigmented (fair) skin types.

Pulsed light for a cleaner dyeing industry: Azo dye degradation by an advanced oxidation process driven by pulsed light

Water pollution by wastewater containing dyes is an environmental issue that can be mitigated by the use of advanced oxidation processes (AOP). Pulsed light (PL) is an emerging food processing technology that uses eco-friendly lamps and can potentially be adapted as light source of an UV-based AOP. In the present work, a PL/H2O2 process was tested for the decolourization of two azo dyes, and a pulsed light/H2O2/ferrioxalate process was tested for the decolourization of one azo dye. The efficiency of the PL/H2O2 process in a batch reactor under different parametric values: dye concentration, pH, H2O2 and salt doses was followed by spectrophotometry and fitted to first-order kinetics; and several degradation products were detected. In the PL/H2O2 process, decolourization rates increased at low dye concentrations and high H2O2 doses, were pH-dependent and were inhibited by the addition of NaCl, Na2SO3 or Na2CO3. More than 50% decolouration was achieved with the PL/H2O2 process for both dyes after applying 54 J/cm2 (25 light pulses). The PL/H2O2/ferrioxalate process achieved >95% decolouration for Methyl orange when applying 21 J/cm2 (10 pulses); that level of energy can be supplied by PL commercial systems in nine and four seconds respectively. No known toxic degradation products were detected. Results show that a PL/H2O2 process has potential to be used for the efficient degradation of dyes from wastewater. Furthermore, the efficacy of this process can be improved by the use of ferrioxalate. PL technology could become an alternative light source to contribute to decrease the environmental impact of wastewater produced by the dyeing industry.

Optimizing parameters for the use of alternate light sources in detecting fragmentary bones: a pilot study

ABSTRACTRecent studies have suggested that alternate light sources (ALS) are effective in detecting bone and teeth fragments at crime scenes. These studies, however, are few in number and provide no consensus as to the optimum combination of wavelength and filter for best detecting bone from non-bone material. Additionally, each study has been conducted using different environments, bone species and varying degrees of exposure to taphonomic factors. The aim of this study was to investigate the optimum parameters of ALS for the detection of bone and teeth fragments in a laboratory setting. Human and non-human bone, and tooth fragments were compared with non-bone material using handheld Rofin Poliflares. Temperature-treated bones (frozen, boiled and burnt) were included to assess if taphonomic factors affected fluorescence. Wavelengths ranging from 415 nm–530 nm were used and fluorescence was recorded using photographic images, and intensity analysed in ImageJ. Results of this pilot study found that the 450 nm Poliflare with orange filter provided the best discrimination of bone/tooth versus non-bone when used at a distance of up to 100 cm from the objects. Fluorescence of heat-treated bones is weakened at distances greater than 30 cm, which should be taken into account when temperature modification to remains is suspected.

Evaluation of the usefulness of the alternative light source (ALS) in differentiating simulated bloodstains

The alternative light source (ALS) is a helpful technique for the detection of biological traces at a crime scene, which allows preservation of the material without destroying it. The aim of this study was to differentiate the human blood from a group of simulated bloodstains, which included: red borscht, raspberry juice, cherry liqueur, cranberry juice, tomato bruschetta, tomato paste, raspberry jam, rust, red spray, red wine and tomato ketchup. Stains, made of different types of material, were illuminated with the ALS emitted by the Mini-CrimeScope 400 (SPEX Forensics) with yellow, dark yellow, orange and red filters. The results of the analysis were presented as a description and also documented in photographs. The usage of light sources without color cut-off filters does not allow us to differentiate unequivocally real bloodstains from the trace evidence imitating or resembling bloodstains. The usage of different color cut-off filters (especially red filter) allowed us to exclude simulated bloodstains made of food and alcohol by using CSS light and light with a wavelength of 535 nm, 515 nm, 455 nm, 415 nm and 300-400 nm. Due to the different optical properties of blood and substances containing vegetable ingredients, forensic experts can differentiate human blood from simulated bloodstains by using the ALS in a non-destructive and quick way already at the crime scene. The ALS may be an example of a method which can replace more commonly used chemical-based screening tests.

Temperature-controlled spectral tuning of full-color carbon dots and their strongly fluorescent solid-state polymer composites for light-emitting diodes.

The development of full-color/white carbon-dot-based light-emitting diodes (LEDs) has been achieved, which show promising applications in full-color and flexible displays, backlights, and novel lighting sources. The gram-level synthesis of these full-color carbon dots (CDs) from citric acid by controlling the temperature has been achieved. By increasing the temperature from 120 to 180 °C, two, four, and six light-emitting CDs can be obtained, for which the emission wavelength shifts from 440 to 585 nm. This result reveals that temperature has a huge impact on the evolution of surface states, that is, increasing the temperature brings about enhanced surface functionalization and passivation, resulting in a red shift of the emission wavelength and enhancement of quantum yield. Then, full-color CDs/polymer composite phosphors are fabricated for efficient phosphor-based LED devices with quench-resistant solid-state fluorescence. By regulating the proportion of various CDs/polymer phosphors, white LEDs are realized with Commission Internationale de L'Eclairage coordinates of (0.32, 0.33) and a color rendering index of 82.7. The as-prepared CD-based full/white color LEDs can prove to be promising candidates for alternative light sources.

Successful analysis of a 100 years old semen stain generating a complete DNA STR profile

We performed forensic investigations on a handkerchief containing seminal fluid deposited 100 years earlier. The aim was to verify the possibility to achieve a complete genetic profile exceeding the limit of success reached until today with a partial semen stain profile stored up to 50 years. The current forensic methods were carried out: Alternative Light Source (ALS), Prostate-Specific Antigen (PSA) Test, autosomal and Y-chromosome Short Tandem Repeats (STRs). ALS inspection was a crucial method in the success of the analysis. On a dried semen stain, fluorescence remains constant for a very long time, allowing possibility to minimize the fabric sample to analyze, in order to preserve specimen for future defense guarantees or to protect historical finding. We achieved positive results in 3 of 6 traces, PSA and DNA results were concordant, only those cuttings that tested positive for PSA yielded DNA profiles. A complete male profile was generated by AmpFlSTR Identifiler Plus and 16 loci profile by AmpFLSTR Yfiler. Considering some historical sources that attributed this handkerchief dated 1916, to a famous Italian poet, the DNA profile found on the handkerchief was compared with a living male descendant, and the comparison of the Y-STR between the two gave positive results, confirming the reliability of the outcomes. The findings achieved by the current forensic method empower the application of this methodology to other forensic cases, especially in past unresolved cases.

Gunshot residue on dark materials: a comparison between infrared photography and the use of an alternative light source.

The pattern of gunshot residue (GSR) includes important information about muzzle-target distance since a larger GSR distribution diameter indicates a larger shooting distance. GSR may not be visible to the naked eye when, for example, it is located on dark textiles. In such cases, further procedures need to be performed in order to visualize the pattern of GSR. Besides chemical procedures, an alternative light source or infrared photography can be utilized for non-destructive GSR visualization. In the work presented, these two techniques are compared based on shooting experiments using 26 different dark textiles. Within the range of the alternative light source, the use of a 440-nm light in combination with an orange-colored filter led to the best visualization of GSR in the form of fluorescent particles. Infrared photography, on the other hand, visualized GSR as dark particles, whereas-ideally-the dark textile reflected the infrared light and appeared bright. The comparison of both techniques revealed that the GSR distribution visualized by infrared photography was not identical to the GSR distribution visualized with 440-nm illumination in combination with an orange-colored filter. We concluded that infrared photography visualizes the inner powder soot zone, whereas illumination at 440nm leads to fluorescence of the outer powder soot zone, which can be visualized using an orange-colored filter. Knowledge of this difference in visualization of the two powder soot zones is important for forensic practitioners assessing firing distances. In the literature, however, this difference is not noted as clearly.

Is the visibility of standardized inflicted bruises improved by using an alternate (‘forensic’) light source?

AimTo study the visibility of standardized inflicted bruises by using an alternate (‘forensic’) light source compared to a white light source. MethodsBruises were inflicted on the flexor site of the forearm (halfway in the middle) in 76 adults, by suddenly allowing a cylindrical metal object (400g) with rounded edges to drop for 1m in a vertically positioned tube. At 0.25, 1, 2, 7 and 14days after this blunt force impact, the impact site on the forearm was photographed with a white light source and subsequently with an alternate light source at 415nm. Visibility of bruises on 170 randomized photographs was assessed on a calibrated monitor by 10 forensic medical specialists (physicians and pathologists) independently in two sessions: (1) with white light source photographs, and (2) after a mean of 11days with greyscale converted alternate light source photographs.Bruise visibility was expressed as a report mark between 1 (very bad) and 10 (excellent), or as ‘no visible bruise’. To determine intra-rater agreement, 10 of 170 photographs were assessed twice (untold to the assessors). In total 3600 (180×10×2) photographs were assessed. Results39 of 73 (53%) participants who completed the study, developed a visible bruise (women more often than men, p<0.001). Inter-rater agreement between assessors was high (mean inter-class coefficient, ICC, for white light source 0.66 (SD 0.14) and for alternate light source ICC 0.73 (0.09)). Intra-rater agreement was excellent (mean ICC 0.88 (SD 0.09)).Mean report marks for bruise visibility, recorded independently by 10 assessors on 170 unique photographs per light source, were significantly higher with an alternate light source than with a white light source, at 1 and 2days after impact: 4.4 (SD 2.0) vs 3.8 (1.8) (p<0.01) and 4.9 (2.1) vs 4.5 (2.0) (p<0.05), respectively.However, these differences were small, as the mean difference (effect size) in report marks were 0.6 (0.5) and 0.4 (0.3), at 1 and 2days after impact, respectively.The other time points showed no statistical significant differences in report marks. ConclusionsBruises after standardized blunt force impact were slightly better visible with an alternate light source than with a white light source after 1 and 2 days, but not after 0.25, 7 and 14 days. The value of using an alternate light source at 415nm to improve bruise visibility was limited in this study.

Effects of Light‐Emitting Diodes on the Growth of Peanut Plants

Core Ideas The ratio R/B = 3:7 light can be used for peanut industry cultivation. By increasing B light‐emitting diode can improve the photosynthetic intensity of peanut leaves. Peanuts can be produced using factory cultivation without the need for land. Light‐emitting diodes (LEDs) are a new type of energy‐saving light source, and their effects on the growth of peanut (Arachis hypogaea L.) plants remain unknown. This study aimed to determine the effects of LEDs on the growth of peanut plants. Plants were exposed to 300 μmol/m2/s photosynthetic photon flux density under a 12 h photoperiod and six different treatments: monochromatic red (R) LED, monochromatic blue (B) LED, three R plus B LED mixtures (7:3, 1:1, 3:7), and fluorescent lamps (FL). At the seedling stage, the fresh weight, dry weight, height, root length, and chlorophyll content were greatest in plants under R/B = 7:3 light. At the blooming stage, the starch concentration and soluble sugars were greatest in plants under R light followed by those under R/B = 1:1 light, the sucrose concentration was greatest under R/B = 7:3 light followed by R/B = 1:1 light, and the chlorophyll concentration was greatest under R/B = 1:1 light. These results showed that R/B = 1:1 light was conducive to peanut growth at the blooming stage. At the pod‐setting stage, the sucrose concentration and soluble sugars were greatest in plants under R/B = 1:1 light, and the starch content was greatest in plants under R/B = 3:7 light. The pod numbers and yields were greater in plants under R/B = 3:7 light than in plants under the other LED lights. R/B = 3:7 light was best for pod growth and yield and could be used as an alternative light source for peanut industry cultivation.

Repeatedly washed semen stains: Optimal screening and sampling strategies for DNA analysis

In many sexual assault cases, bedding and clothing are essential pieces of evidence that are screened for semen stains to gather DNA from the assailant. In some cases, these items have been washed before being seized and sent to the forensic lab. However, few data exist on the optimal methods for detecting and sampling semen stains on washed fabrics. In this paper, we used semen stains washed up to six times to evaluate the efficiency of commonly used screening methods for the detection of semen: alternate light source (ALS), acid phosphatase (AP), prostate specific antigen (PSA) and microscopy (sperm Hy-Liter™, SHL). We also assessed different washing conditions (detergents, washing machines, addition of bleach) and sampling methods (cutting and swabbing). The results show that some semen stain detection strategies, such as ALS, PSA, and SHL, are effective even when the item was washed multiple times. We also show that a complete genetic profile could be obtained from semen stains washed six times. Based on these findings, we present different strategies for the detection and sampling of semen stains depending on the circumstances of the case.

Degradation of azo dye by an UV/H2O2 advanced oxidation process using an amalgam lamp

AbstractThe discharge of dyes into water is an ecological problem that can be alleviated by advanced oxidation processes (AOPs), such as UV/H2O2 treatments. Searching for more efficient light sources is a way to improve AOPs’ efficiency. This work tested the efficiency of an amalgam lamp on the degradation of an azo dye, studying the effect of dye and H2O2 concentrations and pH, and the influence of some salts on the decolouration rate of methyl orange. Actinometry showed that the amalgam lamp system was able to provide a high incident photon irradiance (6.30·10−5 mol/cm2 s). The amalgam lamp‐driven AOP was able to decolourize the dye at pseudo‐first‐order rates of 0.654–4.008 1/min, with increasing rates at low dye concentration and low pH and at high H2O2 concentrations until a maximum value is reached. The results show that the amalgam lamp can be an alternative light source for fast dye degradation by AOPs.

Polarization-multiplexed, dual-comb all-fiber mode-locked laser

Mode-locked fiber lasers that can simultaneously generate two asynchronous ultrashort pulse trains could play an attractive role as the alternative light sources for low-complexity dual-comb metrology applications. Although a few multiplexing schemes to realize such lasers have been proposed and demonstrated, here we investigate the lasing characteristics of a passively mode-locked fiber laser with a finite amount of intracavity birefringence. By introducing a section of polarization-maintaining (PM) fiber into the otherwise-non-PM-single-mode cavity, dual asynchronous pulses with nearly orthogonal states of polarization are generated. With a repetition rate difference of hundreds of hertz, the pulses have well-overlapped spectra and show typical features of polarization-locked vector solitons. It is demonstrated that under an anomalous or net normal dispersion regime, either dual vector solitons or dual dissipative vector solitons can be generated, respectively. Such polarization-multiplexed single single-cavity dual-comb lasers could find further uses in various applications in need of simple dual-comb system solutions.

Simultaneous detection and image capture of biological evidence using a combined 360° camera system with single wavelength laser illumination

Forensic investigators frequently utilise light sources to detect and presumptively identify biological evidence. The instrumentation typically deploys single or multiple wavelength exposures at various intensities, which interact with constituents of biological material, initiating fluorescence or improving contrast between the material and substrate. Documentation using sketches and/or photographic approaches follows detection, which are essential for scene reconstruction. Recent research has demonstrated the simultaneous detection and capture of biological evidence using a 360° camera system combined with an alternate light source exhibiting broad wavelength ranges of light. Single wavelength light sources reportedly offer enhanced sensitivity, due to the increased light intensity and narrower bandwidth of light, although their combined use with a 360° camera system has not yet been explored.Samples of human blood, semen, saliva, and latent fingermarks were deposited on to a variety of substrates. A 360° camera system combined with a laser light source was used to detect and capture the samples. Ten participants were asked to detect the samples on images of the substrates without ground truth knowledge. It was possible to detect and capture biological evidence, although success varied according to substrate colour and light intensity. Advantageously, presumptive screening for biological fluids and the simultaneous location and visualisation of such evidence as part of a 360° panorama of the scene for contextual purposes was permitted. There was no fluorescent response from the fingermarks, although the oblique lighting effects appeared sufficient to aid mark detection in some circumstances. The use of single wavelength illumination clearly facilitates identification of a range of forensically important material. When coupled with a 360-degree camera, this allows for simultaneous identification and recording of such evidence in the context of the whole environment.

Study on Efficiency of Alternate Light Source for Detection of Latent Fingerprints

Study on Efficiency of Alternate Light Source for Detection of Latent Fingerprints