Innovations in laboratory-based dynamic micro-CT to accelerate in situ research.

In the past few years, dynamic computed tomography (CT) approaches or uninterrupted acquisitions of deforming materials have rapidly emerged as an essential technique to understand material evolution, facilitating in situ investigations ranging from mechanical deformation to fluid flow in porous materials and beyond. Developments at synchrotron facilities have led this effort, pointing to the future of the technique. In the laboratory, recent developments at TESCAN XRE have made it possible to image, reconstruct and inspect dynamic processes in the laboratory with a temporal resolution below 10 s, meaning that an entire acquisition from 0 to 360° is completed within 10 s. The aim of this study is to explore the challenges and innovations that have led to the ability to perform high speed, dynamic acquisitions. A unique horizontally rotating gantry based micro-CT system was developed to facilitate complex in situ experiments. In doing so, the sample stays fixed while source and detector are uninterruptedly rotating around a vertical axis. In this work, the dynamic CT method with this rotating gantry based system will be described by two application examples: (1) deformation and collapse of a delicate beer foam and (2) in situ baking process of pastry. For the pastry baking process, an oven was needed to reach baking temperature. In a conventional micro-CT system, where the sample rotates, it is not so obvious to rotate an oven with sensor and heating cables. On the other hand, the delicate foam of a collapsing beer head is able to rotate, but because of the tangential convection during fast rotation (<10 s), it could influence the bubble detachment and liquid drainage and thus also the foam degradation. To investigate both processes, a horizontally rotating gantry based micro-CT is required. For both examples it was possible to quantify the key parameters such as pore size and distribution to better understand the rise and fall of porous foams. These examples will highlight the recent progress in adapting micro-CT workflows to accommodate uninterrupted imaging of dynamic events and point to opportunities for future continued development. LAY DESCRIPTION: Micro-CT allows the nondestructive visualisation of internal structures and is being used routinely in the field of Material Science, Geoscience, Life Science and more. Because of its nondestructive aspect, micro-CT is optimal to take repetitive scans of the same sample over time. The combination of taking different scans over time is so called time-resolved CT. By doing so, crucial insights can be obtained on how materials form, deform and perform over time or under certain external conditions. TESCAN XRE have made it possible to image, reconstruct and inspect dynamic processes in the laboratory with a temporal resolution below 10 s. The dynamic CT method will be described through the lens of two application examples: (1) deformation and collapse of a delicate beer foam and (2) in situ baking process of pastry. These examples will highlight the recent progress in adapting micro-CT workflows to accommodate imaging of dynamic events and point to opportunities for future continued development.

[Testing of vaccines. The challenge of testing complex combination vaccines]. / Prüfung von Impfstoffen. Die Herausforderung der Prüfung komplexer Kombinationsimpfstoffe.

Vaccines are biologicals. This group of medicinal products is produced with a predefined variability based on the biological starting materials used. Vaccines are subject to official control authority batch release performed by the Paul-Ehrlich-Institut (PEI). To release batches to the market, experimental testing has to be conducted by an official medicines control laboratory as the PEI. It is the aim of this independent testing to demonstrate the conformity of quality criteria with conditions set in the marketing authorization for each lot produced. The testing is performed on the basis of vaccine specific batch release guideline and due to the difficult and time consuming testing procedures often run in parallel with manufacturers testing. If test results comply with the predefined criteria, the lot in question is released. This article describes the challenge of official control authority batch release testing of two complex combination vaccines.

Mechanical properties of soft human tissues under dynamic loading.

The dynamic response of soft human tissues in hydrostatic compression and simple shear is studied using the Kolsky bar technique. We have made modifications to the technique that allow loading of a soft tissue specimen in hydrostatic compression or simple shear. The dynamic response of human tissues (from stomach, heart, liver, and lung of cadavers) is obtained, and analyzed to provide measures of dynamic bulk modulus and shear response for each tissue type. The dynamic bulk response of these tissues is easily described by a linear fit for the bulk modulus in this pressure range, whereas the dynamic shearing response of these tissues is strongly non-linear, showing a near exponential growth of the shear stress.

Computational and experimental models of the human torso for non-penetrating ballistic impact.

Both computational finite element and experimental models of the human torso have been developed for ballistic impact testing. The human torso finite element model (HTFEM), including the thoracic skeletal structure and organs, was created in the finite element code LS-DYNA. The skeletal structure was assumed to be linear-elastic while all internal organs were modeled as viscoelastic. A physical human surrogate torso model (HSTM) was developed using biosimulant materials and the same anthropometry as the HTFEM. The HSTM response to impact was recorded with piezoresistive pressure sensors molded into the heart, liver and stomach and an accelerometer attached to the sternum. For experimentation, the HSTM was outfitted with National Institute of Justice (NIJ) Level I, IIa, II and IIIa soft armor vests. Twenty-six ballistic tests targeting the HSTM heart and liver were conducted with 22 caliber ammunition at a velocity of 329 m/s and 9 mm ammunition at velocities of 332, 358 and 430 m/s. The HSTM pressure response repeatability was found to vary by less than 10% for similar impact conditions. A comparison of the HSTM and HTFEM response showed similar pressure profiles and less than 35% peak pressure difference for organs near the ballistic impact point. Furthermore, the peak sternum accelerations of the HSTM and HTFEM varied by less than 10% for impacts over the sternum. These models provide comparative tools for determining the thoracic response to ballistic impact and could be used to evaluate soft body armor design and efficacy, determine thoracic injury mechanisms and assist with injury prevention.

Microstructural evolution during sintering of copper particles studied by laboratory diffraction contrast tomography (LabDCT).

Pressureless sintering of loose or compacted granular bodies at elevated temperature occurs by a combination of particle rearrangement, rotation, local deformation and diffusion, and grain growth. Understanding of how each of these processes contributes to the densification of a powder body is still immature. Here we report a fundamental study coupling the crystallographic imaging capability of laboratory diffraction contrast tomography (LabDCT) with conventional computed tomography (CT) in a time-lapse study. We are able to follow and differentiate these processes non-destructively and in three-dimensions during the sintering of a simple copper powder sample at 1050 °C. LabDCT quantifies particle rotation (to <0.05° accuracy) and grain growth while absorption CT simultaneously records the diffusion and deformation-related morphological changes of the sintering particles. We find that the rate of particle rotation is lowest for the more highly coordinated particles and decreases during sintering. Consequently, rotations are greater for surface breaking particles than for more highly coordinated interior ones. Both rolling (cooperative) and sliding particle rotations are observed. By tracking individual grains the grain growth/shrinkage kinetics during sintering are quantified grain by grain for the first time. Rapid, abnormal grain growth is observed for one grain while others either grow or are consumed more gradually.

Automated Measurement Technique for the Determination of Regional Skull and Scalp Constituent Thickness.

The human skull is a multi-layered composite system critical in protecting the brain during head impact. Head impact studies investigating skull injury thresholds have suggested that the skull and scalp thickness affect the risk of fracture. Therefore, accurately determining the dimensions of skull-scalp constituents is a necessary step in attributing the contribution to response, failure mechanisms and in developing high fidelity human models. However, prior methods to collect these data include physical measurements of biopsies and manual segmentation in X-ray images. These methods are invasive and impractical for clinical applications, or insufficient to characterize the regional variance in the skull-scalp constituents for a full mechanical strength characterization. The newly developed methods in this study describe an automated, regional, and objective-based measurement technique to characterize the average thickness and variance in skull and scalp constituents using quantitative computed tomography (QCT). The developed approach was successfully employed on 7 specimens at 5 anatomically defined locations. Results report the thicknesses for each layer, with the layer of greatest variation being the trabecular bone (diploë) having a standard deviation of 35.6% of its mean thickness. These results will be used to define skull morphology for modeling relative impact injury risk that will be experimentally validated.

Non-destructive mapping of grain orientations in 3D by laboratory X-ray microscopy.

The ability to characterise crystallographic microstructure, non-destructively and in three-dimensions, is a powerful tool for understanding many aspects related to damage and deformation mechanisms in polycrystalline materials. To this end, the technique of X-ray diffraction contrast tomography (DCT) using monochromatic synchrotron and polychromatic laboratory X-ray sources has been shown to be capable of mapping crystal grains and their orientations non-destructively in 3D. Here we describe a novel laboratory-based X-ray DCT modality (LabDCT), enabling the wider accessibility of the DCT technique for routine use and in-depth studies of, for example, temporal changes in crystallographic grain structure non-destructively over time through '4D' in situ time-lapse studies. The capability of the technique is demonstrated by studying a titanium alloy (Ti-ß21S) sample. In the current implementation the smallest grains that can be reliably detected are around 40 µm. The individual grain locations and orientations are reconstructed using the LabDCT method and the results are validated against independent measurements from phase contrast tomography and electron backscatter diffraction respectively. Application of the technique promises to provide important insights related to the roles of recrystallization and grain growth on materials properties as well as supporting 3D polycrystalline modelling of materials performance.

Experimental Characterization of the Anatomical Structures of the Lumbar Spine Under Dynamic Sagittal Bending.

Underbody blast (UBB) events transmit high-rate vertical loads through the seated occupant’s lumbar spine and have a high probability of inducing severe injury. While previous studies have characterized the lumbar spine under quasi-static loading, additional work should focus on the complex kinetic and kinematic response under high loading rates. To discern the biomechanical influence of the lumbar spine’s anatomical structures during dynamic loading, the axial force, flexion-extension moments and range of motion for lumbar motion segments (n=18) were measured during different states of progressive dissection. Pre-compression was applied using a static mass while dynamic bending was applied using an offset drop mass. Dynamic loading resulted in peak axial loads of 4,224±133 N, while maximum peak extension and flexion moments were 19.6±12.5 and -44.8±8.6 Nm in the pre-dissected state, respectively. Upon dissection, transection of the interspinous ligament, ligamentum flavum and facet capsules resulted in significantly larger flexion angles, while the removal of the posterior elements increased the total peak angular displacement in extension from 3.3±1.5 to 5.0±1.7 degrees (p=0.002). This study provides insight on the contribution of individual anatomical components on overall lumbar response under high-rate loading, as well as validation data for numerical models.

Material Parameter Determination of an L4-L5 Motion Segment Finite Element Model Under High Loading Rates.

Underbody blast (UBB) events impart vertical loads through a victim’s lumbar spine, resulting in fracture, paralysis, and disc rupture. Validated biofidelic lumbar models allow characterization of injury mechanisms and development of personal protective equipment. Previous studies have focused on lumbar mechanics under quasi-static loading. However, it is unclear how the role and response of individual spinal components of the lumbar spine change under dynamic loading. The present study leverages high-rate impacts of progressively dissected two-vertebra lumbar motion segments and Split-Hopkinson pressure bar tissue characterization to identify and validate material properties of a high-fidelity lumbar spine finite element model for UBB. The annulus fibrosus was modeled as a fiber-reinforced Mooney-Rivlin material, while ligaments were represented by nonlinear spring elements. Optimization and evaluation of material parameters was achieved by minimizing the root-mean-square (RMS) of compressive displacement and sagittal rotation for selected experimental conditions. Applying dynamic based material models and parameters resulted in a 0.42% difference between predicted and experiment axial compression during impact loading. This dynamically optimized lumbar model is suited for cross validation against whole-lumbar loading scenarios, and prediction of injury during UBB and other dynamic events.

Nutritional status and serum lipids of a rural population in Northeast Thailand--an example of health transition.

An investigation was undertaken in Northeast Thailand, a country undergoing rapid health transition, to find out whether there is a likelihood that the nutritional and lipid pattern of an adult population in Northeast Thailand is related to coronary heart disease in the same way as in western countries. In a cross-sectional study, the body mass index (BMI) and the waist-hip ratio as well as the important plasma lipids were determined. The nutritional status and the lipid profile of the predominantly middle-aged population is characterised by a generally favourable nutritional status and lipid concentrations, where the distribution, indicated by the medians, of the relevant variables over the total population is concerned. A rather high proportion of individuals was found to be overnourished and to have high triglyceride levels. Individuals with high triglyceride levels run a risk of developing coronary heart disease only when the LDL-HDL fraction is above 5. Only 3% of the total population investigated had a LDL-HDL ratio above that value. Since hypertriglyceridaemia is also linked to the insulin-resistant syndrome, it is concluded that, if the mortality of coronary heart disease increases in future, then this must be accounted probably more to the after-effects of the insulin-resistant syndrome than to the direct effect of an atherogenic lipid pattern. This view is supported by a high prevalence of impaired glucose tolerance (IGT) and non-insulin dependent diabetes mellitus (NIDDM) in the population under survey. Preventive measures in the area should concentrate among others on reducing overnutrition, especially among women, and increasing physical activity and screening for NIDDM.

Mouth protectors and oral trauma: a study of adolescent football players.

A total of 754 junior high school and high school football players from the Birmingham, AL, area were studied to determine the extent of sports-related oral trauma among players. More than half the oral injuries and more than a third of the concussions were reported in sports other than football. Basketball and baseball players had a high prevalence of hard tissue oral trauma with virtually none of the players wearing mouth protectors. The results of this study indicate that current mouth protector designs are helpful in preventing hard tissue trauma, yet additional soft tissue protection is indicated in football mouth protector design.

Malaria control through impregnated bednets--a pilot project in selected villages in Lao PDR.

In 7 villages on the foothills of the Houayxai district of the Bokeo Province in Lao PDR between midyear 1995 to midyear 1997 an attempt was made to test the acceptability and use of DDT impregnated bed nets as well as environmental and behavioral risk factors. About 380 women between 15 to 45 years old and their children in the age range of 1 to 14 years had been studied. A pre-tested questionnaire had been applied and blood from women and children was taken from the finger prick and a conventional thick and thin blood smear was performed, fixed Giemsa stained and examined for malaria parasites. DDT (dichlorodiphenyltrichloroethane) impregnated mosquito nets were distributed in the intervention villages. The availability of mosquito nets increased statistically significant from approximately 50% to 70% for all family members in the intervention area between 1995 and 1997 and statistically significant decreased in the control area from 79% to 45.1%. There was a statistically significant decrease in malaria attacks as claimed by the females for the intervention area but not for the control villages. The proportion of positive blood smears did decrease overall for women and children in between 1995 to 1997. Occupation, location of the house and use of mosquito nets had been determined as the most important risk factors.

Community based intervention of iron deficiency anemia in females and iodine deficiency disorders in school children in Lao PDR.

Under the supervision of the central and local health authorities, a pilot project was conducted in four villages in the Luangprabang Province, Lao PDR. The objective of the project was to test different regimes to supplement females with oral iron preparations to reduce iron deficient anemia (IDA) and control iodine deficiency disorders (IDD) in school children. Compared with iron sulphate tablets, iron fumerate tablets were well accepted and good compliance results were achieved. Hemoglobin concentration improved only in the group of females taking iron fumerate tablets. The goiter rate decreased from approximately 90% to about 45% for school children, regardless of whether iodine salt were used by their families or whether iodine capsules were used to treat the children. The latter attempt was hampered by the fact that also in the control village iodine fortified salt was used. This was due to a governmental attempt to control IDD nation-wide. Therefore, also in the control village a significant decrease in the goiter rate was observed.

Control of intestinal parasitic infection--a pilot project in Lao PDR.

Intestinal helminths are a very common but still rather unrecognized public health problem. An attempt was undertaken to control the three important parasites, ie Ascaris, Trichuris and hookworm. Two villages in Vientiane Province in Lao PDR were selected, one as an intervention and the other as control village. Intervention measures started by providing mass treatment against Ascaris, Trichuris, hookworm and other intestinal parasitic infections in both villages. Health education and other intervention measures were implemented in the intervention village, which significantly influenced the re-infection rates in this village. These achievements were not due to an improvement of the availability of toilets or personal hygiene alone but more to the villagers' improved understanding of the route of the parasitic infections. It was concluded that intervention methods should be directed more towards particular age groups. Particular attention should be paid to control parasitic infections among females.

Reproductive health in selected villages in Lao PDR.

The aim of the project was to improve the knowledge and attitude towards birth spacing by training the villagers in the selected villages of Vientiane Province in Lao PDR in family planning, providing them with the various family planning methods, and improving antenatal (ANC) and postnatal (PNC) care in the villages. Throughout the province, traditional birth attendants (TBA) were trained on several occasions during the project period. There were clear indications that reproductive health improved between 1995 and 1997. Considerable improvements were observed in the percentage of women making use of ANC and practising birth spacing by using some form of contraception or other. The most common methods used were contraceptive pills and injectables. In the case of child mortality a slight decrease was found in the percentage of women having their first pregnancy below the age of 18 years. A still unsolved problem is the high number of abortions.

Nutritional status of pre-school children and women in selected villages in the Suvannakhet Province, Lao PDR--an intervention trial.

A project to promote the health and nutritional status of women and pre-school children was started from 1995 to 1997 in three villages in Suvannakhet Province, Lao PDR. One village served as control. In 1995, for the baseline survey, 456 females, and in 1997, for the final evaluation, 363 females from the four villages volunteered for further investigations. An attempt was made to involve all females in the reproductive age residing in the villages. At the same time also the nutritional status of 321 and about 540 randomly selected pre-school children respectively was also assessed through physical examination and anthropometric measurements. Intervention measures included introducing growth charts and taking regular anthropometric measurements of women in the reproductive age and of pre-school children. Training in nutritional aspects such as giving colostrum to new-borns, prepare proper weaning food and supplementary feeding, animal-raising and home gardening was also introduced and provided to health personnel, village leaders and in women clubs. Special attention was given to the control of acute infectious diseases. The conventional EPI program was enforced as well. Health education in matters of mother and child health care was also provided. The proportion of undernourished women was rather high at about 15%. For pre-school children, the proportion of wasting was around 5%, and of stunting 50% and above. Intervention did not improve the nutritional status either of the women or of the children. It was concluded that the time span of two years is too short for a decrease in the proportion of undernourishment to be observed. An improvement was achieved for some indicators of mother and child health care. This seems to indicate the population's willingness to follow suggestions to improve their health. Most probably, if attempts to improve the nutritional status were continued, an improvement in this aspect could also be observed, if the population can be encouraged to take actions and develop initiatives by themselves.

Promotion of the health of rural women towards safe motherhood--an intervention project in northeast Thailand.

An intervention project focusing on the health of women in the reproductive age was conducted in three districts of Khon Kaen Province, northeast Thailand between 1991 and 1996. Main emphasis was placed on improving reproductive health, the nutritional status including the iron deficiency anemia (IDA) as well as iodine deficiency disorders (IDD), and the parasitic diseases liver fluke (Opisthorchis viverrini) and hookworm. For implementation a community based Primary Health Care approach was used including the training of health officials in health matters, primary health care workers and villagers as well as enhancing health education and the dissemination of health information. The health delivery system was encouraged to take appropriate actions such as in the treatment of parasitic diseases and the control of IDA and IDD. Monitoring was done on a regular basis. The outcome of the project was assessed by comparing baseline data compiled from a random sample of the target population with the results of the final evaluation. An attempt to compare results obtained from villages within and outside of the project area failed most probably because of spill over effects. A number of important indicators on family planning and mother and child health care improved during the time the project was implemented; this included practising family planning, and participation in antenatal care. Also the proportion of females becoming pregnant for the first time when 20 years or older increased. Child-raising also improved in that almost all females gave colostrum to their babies by this time. Almost 75% of the women breast-fed their children. Improvements occurred in the nutritional status as far as the micronutrients iron and iodine were concerned, however the overall nutritional status of females did not change, but a rather high proportion of females were found to be overnourished. The project failed in reducing abortion and the proportion of females becoming pregnant when they are 18 years old or younger. It was also not possible to improve the usage of postnatal care. As anticipated, the results achieved so far are most suitable in serving as a training ground and providing a favorable example to improve family planning, mother- and child health care, and also the general health of females in the region, particularly in neighboring countries such as Lao PDR, Cambodia and Vietnam.

Complete intrusion of a maxillary right primary central incisor.

This clinical article presents a rare presentation of complete intrusion of a maxillary right primary central incisor. Routine examination of a 29-month old female patient revealed an intrusion injury where the primary central incisor was displaced through the floor of the nasal cavity. The traumatic impaction was erroneously diagnosed as an avulsion injury by the attending emergency room physician and later discovered by the dental team during routine care. The injury was documented with radiographs. The intruded incisor was removed through the right naris utilizing general anesthesia to manage behavior and surgical access. This article emphasizes the importance of radiographs and demonstrates the need to involve the dental professional in initial assessment of dental trauma.

Prevalence of abnormal glucose tolerance in Khon Kaen Province and validity of urine stick and fasting blood sugar as screening tools.

Three hundred and fifty-five individuals, 152 males and 203 females, aged between 30 and 74 years, were randomly selected in a two stage selection process from rural communities in three districts of Khon Kaen Province, Northeast Thailand. The prevalence of impaired glucose tolerance (IGT) and non-insulin dependent diabetes mellitus (NIDDM) in the rural area of Northeast Thailand were measured. In addition, the validity of the urine stick and fasting blood sugar as screening tools against the two hours glucose loading test as golden standard were determined. The survey was conducted in July 1995. The glucose loading test was performed on 277 individuals. IGT and NIDDM were classified according to current World Health Organization suggestions. Prevalence rates for IGT were 18.1 per cent and for NIDDM 11.9 per cent. No difference was found between males and females, also when controlled for age. NIDDM prevalence increased with age but IGT rates already were high in the younger age groups. This finding suggests that IGT precedes NIDDM in Thailand. The validity of the urine stick as a screening tool in communities was insufficient, with a sensitivity of less than 20 per cent. When using fasting blood sugar as a screening test, the sensitivity was close to 44 per cent and the specificity 90 per cent. It is concluded that the urine stick is not a useful screening tool and the method of using blood sugar concentrations for screening have to be improved before it can be applied within communities.