Application of Standoff LIF to Living and Inactivated Bacteria Samples

To minimize the impact of an airborne bio-agent output, sensitive, specific and swift detection and identification are essential. A single method can hardly meet all of these requirements. Point sensors allow highly sensitive and specific identification but are localized and comparatively slow. Most laser-based standoff systems lack selectivity and specificity but provide real-time detection and classification in a wide region with additional information about location and propagation. A combination of both methods allows benefiting from their complementary assets and may be a promising solution to optimize detection and identification of hazardous substances. Here, we present progress for an outdoor bio-detector based on laser-induced fluorescence (LIF) developed at the DLR Lampoldshausen. After excitation at 280 and 355 nm, bacteria species express unique fluorescence spectra. Upon deactivation, the spectral features change depending on the applied method

Repeat infection with Chlamydia trachomatis: a prospective cohort study from an STI-clinic in Stockholm

BACKGROUND: Infection with genital Chlamydia trachomatis (Ct) is the most common notifiable sexually transmitted infection (STI) in Sweden. A mutated Chlamydia, nvCT, has contributed to the increase. The occurrence of repeat infections is not investigated in Sweden. The current paper presents the study protocol for the first Swedish clinical investigation of repeat Chlamydial infection. The concern of the study is whether a Chlamydia infection at inclusion indicates an increased risk for Chlamydia at follow-up after 6–8 months, gender-specific risk factors for and clinical presentation of repeat infections. METHODS AND DESIGN: Sesam City is a drop-in clinic in the city centre of Stockholm. Patients 20 years and older are admitted. During 2007, the clinic had 15 000 visits, 60% made by men. In December 2007, a cohort study began, and data collection was finished in April 2009. A total of 2813 study participants aged 20–39 years were recruited. Data collection included an anonymous self-administered paper-and-pen questionnaire on sexual behaviour, reproductive health and history of Chlamydia, and condom use. Chlamydia tests were performed by self-sampled specimens, analyzed by the ProbeTec (Becton Dickinson) method, Ct-positive specimens also analyzed with a nvCT-specific method. Data from medical records were summarized in clinical report forms. Patients positive for Chlamydia were retested 4 weeks after treatment. Contact tracing covered sexual contacts during the last 12 months. At follow-up 6–8 months after inclusion, Chlamydia tests were performed, and a new questionnaire and CRF completed. DISCUSSION: A STI-clinic-based prospective cohort study allowed us to survey 2813 adult patients. The collected data will provide gender-specific information on the occurrence of and risk for repeat Chlamydia infection, the occurrence of nvCT, and clinical data and information on sexual behaviour and reproductive health, risk-taking and condom use

Experimental and numerical analysis of atmospheric propagation of high energy laser

The transmission of high power laser radiation through the atmosphere is influenced by turbulent motion of the air. As a result the beam experiences an alteration regarding its position and its distribution, which increases with increasing propagation length. In order to analyze the atmospheric influence on the laser beam propagation a disk laser with a maximum output power of 6 kW and a wavelength of 1.03 µm is operated on a 130 m long free transmission laser test range in Lampoldshausen. The test range is equipped with a variety of sensors, which continuously monitor the current status of the weather conditions. Power sensors and camera systems at the beginning and the end of the test range measure the laser beam parameters before and after propagation. The experimental results are compared with a numerical analysis of the laser beam propagation performed by the software TALAP (Turbulent Atmosphere and Laser Beam Propagation), developed at the Institute of Technical Physics of DLR. It is based on the Kolmogorov turbulence model, which considers turbulent cells of different scale sizes. First measurements of power transmission, diameter of the laser beam and variations of its center of gravity are performed on a sunny and on a rainy day. The results show a good correlations to the measurements of the turbulence strength and the visibility. A comparison to the numerical analysis has shown coincidences. Future measurements will be performed at different weather conditions and seasons. Experimental results will be used to modify the simulation software, if necessary

Standoff laser induced fluorescence of living and inactivated bacteria

Biological hazards, such as bacteria, represent a non-assessable threat in case of an accident or a terroristic attack. Rapid detection and highly sensitive identification of released, suspicious substances at low false alarm rates are challenging requirements which one single technology cannot cope with. It has been shown that standoff detection using laser-induced fluorescence (LIF) can provide information on the class of bioorganic substances in real-time1. In combination with traditional, highly sensitive, but non-standoff methods, the time for identification of the threat can be optimized. This work is aimed at the selectivity of LIF technology for different bacterial strains. A second important aspect examines how to deal with inactivated bacteria and how their fluorescence signature changes after deactivation. LIF spectra of closely and more distantly related bacterial strains are presented as well as spectra of bacteria treated by different inactivation methods

UAV-getragenes laserinduziertes Fluoreszenzspektroskopie-System zur aktiven Ferndetektion von Gefahrstoffen auf Oberflächen

LUCS ist ein innovatives drohnengestütztes Ferndetektionssystem, welches im Rahmen der DLR Sicherheitsforschung am DLR Institut für Technische Physik entwickelt wurde. Basierend auf einer laserspektroskopischen Technik ist das UAV-gestützte System insbesondere für den Einsatz zur berührungslosen Erkennung und Klassifizierung von chemischen und biologischen Gefahrstoffen auf Oberflächen ausgelegt. Mit einer Messzeit von ca. 100 ms können aus einer Detektionsdistanz zwischen 8 – 10 m innerhalb kürzester Zeit die Fluoreszenzeigenschaften des Probenmaterial untersucht werden

Compact setup for standoff Laser induced breakdown spectroscopy of radioactive materials

Radioactive materials present a major threat and can cause severe direct and long term injuries to humans as experienced i.e. in the Fukushima and Chernobyl nuclear plant catastrophes. Furthermore, intended use of radiological dispersal devices can be used to spread radioactive materials over large areas. Detecting these hazards and investigating the status of contaminated areas a remote standoff determination of nuclear fission products would serve as a helpful tool for first responders and damage control teams. Laser induced breakdown spectroscopy (LIBS) offers a unique possibility for the identification of elements as nuclear fission products and is even able to distinguish different isotopes of the same species. Within this scope and based on experiences with a high power / long distance (> 100 m) LIBS setup we present a new compact and low power setup. The compactness allows for handheld operation as well as mounted on a small robot or on an unmanned aerial vehicle (UAV) an advanced setup could be controlled remotely and would be able to safely determine radioactive materials

Conceptual design for an ultra-sensitive bioaerosol detection system

The detection of aerosols in general and bioaerosols more specific has gained an increased importance in multiple fields. While environmental scientists are increasingly interested in the impacts of aerosols onto climatic effects, researchers in the security sector are looking for ways to remotely detect dangerous substances from safe distances. Additionally, due to the Corona pandemic, the detection of bioaerosols has gained significant relevance in sectors like public health, transportation, and aviation. As a result, more accurate, i.e. sensitive and specific, measurement equipment is needed. Here we present the design concept for a new sensor system designed to measure thin bioaerosol clouds. For the detection air samples are excited with laser light to generate a signal based on laser induced fluorescence. The fluorescence is collected in an integration sphere to optimize signal. Inside the integration sphere multiple sensors are placed, each combined with a filter to exclude all signals not belonging to a certain, agent specific wavelength interval. Through the intelligent combination of spectral intervals, a specific characteristic of the studied air sample is measured. Based on the measured characteristic a classification is performed to determine the category of the sample. Development aims at testing indoor air quality in real time

Fluorescence signatures of SARS CoV-2 spike S1 proteins and an human ACE-2: excitation-emission maps and fluorescence lifetimes

Significance: Fast and reliable detection of infectious SARS-CoV-2 virus loads is an important issue. Fluorescence spectroscopy is a sensitive tool to do so in clean environments. This presumes a comprehensive knowledge of fluorescence data. Aim: We aim at providing fully featured information on wavelength and time-dependent data of the fluorescence of the SARS-CoV-2 spike protein S1 subunit, its receptor-binding domain (RBD), and the human angiotensin-converting enzyme 2, especially with respect to possible optical detection schemes. Approach: Spectrally resolved excitation-emission maps of the involved proteins and measurements of fluorescence lifetimes were recorded for excitations from 220 to 295 nm. The fluorescence decay times were extracted by using a biexponential kinetic approach. The binding process in the SARS-CoV-2 RBD was likewise examined for spectroscopic changes. Results: Distinct spectral features for each protein are pointed out in relevant spectra extracted from the excitation-emission maps. We also identify minor spectroscopic changes under the binding process. The decay times in the biexponential model are found to be [Formula: see text] and [Formula: see text]. Conclusions: Specific material data serve as an important background information for the design of optical detection and testing methods for SARS-CoV-2 loaded media

Autosomal Recessive Dilated Cardiomyopathy due to DOLK Mutations Results from Abnormal Dystroglycan O-Mannosylation

Genetic causes for autosomal recessive forms of dilated cardiomyopathy (DCM) are only rarely identified, although they are thought to contribute considerably to sudden cardiac death and heart failure, especially in young children. Here, we describe 11 young patients (5–13 years) with a predominant presentation of dilated cardiomyopathy (DCM). Metabolic investigations showed deficient protein N-glycosylation, leading to a diagnosis of Congenital Disorders of Glycosylation (CDG). Homozygosity mapping in the consanguineous families showed a locus with two known genes in the N-glycosylation pathway. In all individuals, pathogenic mutations were identified in DOLK, encoding the dolichol kinase responsible for formation of dolichol-phosphate. Enzyme analysis in patients' fibroblasts confirmed a dolichol kinase deficiency in all families. In comparison with the generally multisystem presentation in CDG, the nonsyndromic DCM in several individuals was remarkable. Investigation of other dolichol-phosphate dependent glycosylation pathways in biopsied heart tissue indicated reduced O-mannosylation of alpha-dystroglycan with concomitant functional loss of its laminin-binding capacity, which has been linked to DCM. We thus identified a combined deficiency of protein N-glycosylation and alpha-dystroglycan O-mannosylation in patients with nonsyndromic DCM due to autosomal recessive DOLK mutations