Quantitative material analysis using secondary electron energy spectromicroscopy

This paper demonstrates how secondary electron energy spectroscopy (SEES) performed inside a scanning electron microscope (SEM) can be used to map sample atomic number and acquire bulk valence band density of states (DOS) information at low primary beam voltages. The technique uses an electron energy analyser attachment to detect small changes in the shape of the scattered secondary electron (SE) spectrum and extract out fine structure features from it. Close agreement between experimental and theoretical bulk valance band DOS distributions was obtained for six different test samples, where the normalised root mean square deviation ranged from 2.7 to 6.7%. High accuracy levels of this kind do not appear to have been reported before. The results presented in this paper point towards SEES becoming a quantitative material analysis companion tool for low voltage scanning electron microscopy (LVSEM) and providing new applications for Scanning Auger Microscopy (SAM) instruments.

Community-based integrated approach to changing women's family planning behaviour in Pakistan, 2014-2016

Setting: Karachi, Pakistan. Objective: To assess the effectiveness of a community-based integrated approach in changing women's behaviour regarding contraceptive use. Design: The Sukh Initiative is a multipronged approach with door-to-door services using community health workers to provide quality family planning/reproductive health services at both public and private facilities and a 24/7 family planning helpline service that provides youth skill-based education. Methods: Retrospective pre- and post-intervention data using samples of 5140 and 3810 women, respectively. Results: The contraceptive prevalence rate increased by 10.7%, from 42.3% at baseline to 53.0% mid-intervention, with an increase in use of modern contraceptive methods of 9.2%. A significant association was found between door-to-door counselling and the use of contraceptive methods (OR 3.4, 95%CL 2.9-4.1) and access to public and private facilities for modern contraceptives (OR 2.4, 95%CL 2.0-3.0). However, support group meetings and 24/7 helpline use did not show any association with use of contraceptive method. Conclusion: The study helped to increase access to and choice of family planning services through a community-based approach that successfully reduced unmet needs and improved continuity in contraceptive use.

Brightness measurement of an electron impact gas ion source for proton beam writing applications

We are developing a high brightness nano-aperture electron impact gas ion source, which can create ion beams from a miniature ionization chamber with relatively small virtual source sizes, typically around 100 nm. A prototype source of this kind was designed and successively micro-fabricated using integrated circuit technology. Experiments to measure source brightness were performed inside a field emission scanning electron microscope. The total output current was measured to be between 200 and 300 pA. The highest estimated reduced brightness was found to be comparable to the injecting focused electron beam reduced brightness. This translates into an ion reduced brightness that is significantly better than that of conventional radio frequency ion sources, currently used in single-ended MeV accelerators.

High rate composting of herbal pharmaceutical industry solid waste

High rate composting studies of hard to degrade herbal wastes were conducted in a 3.5 m(3) capacity rotary drum composter. Studies were spread out in four trials: In trial 1 and 2, one and two turns per day rotation was observed, respectively, by mixing of herbal industry waste with cattle (buffalo) manure at a ratio of 3:1 on wet weight basis. In trial 3 inocula was added in raw waste to enhance the degradation and in trial 4 composting of a mixture of vegetable market waste and herbal waste was conducted at one turn per day. Results demonstrated that the operation of the rotary drum at one turn a day (trial 1) could provide the most conducive composting conditions and co-composting (trial 4) gave better quality compost in terms of temperature, moisture, nitrogen, and Solvita maturity index. In addition a FT-IR study also revealed that trial 1 and trial 4 gave quality compost in terms of stability and maturity due to the presence of more intense peaks in the aromatic region and less intense peaks were found in the aliphatic region compared with trial 2 and trial 3.

Dual interventional approach of endoscopic reboring in completely stenosed rectal anastomosis using radiology guidance: a novel technique

OBJECTIVE

Rectal stricture/stenosis is a well-recognized complication following anterior resection. Completely stenosed rectal anastomoses have been conventionally treated conservatively with permanent stoma. The surgical alternatives are either a redo low resection with its accompanying hazards or formation of a permanent colostomy. We describe a simple method of treating anastomotic stenoses using a novel technique in patients with a defunctioned bowel.

METHOD

Three patients with complete stenosis of a rectal anastomosis following anterior resection underwent this novel technique with informed consent. A stenosis with no identifiable lumen was diagnosed at the time of examination under anaesthetic (EUA) or by contrast enema. Using a novel technique of combined endoscopic and radiology guidance, the anastomotic stenosis was rebored and subsequently dilated to restore bowel continuity.

RESULTS

There were no complications observed following this procedure. Two of the three patients needed repeat endoscopic dilatation. All patients had restoration of the lumen in the anastomosis and subsequently underwent closure of ileostomy and made an uneventful recovery.

CONCLUSION

Combined endoscopic dilatation under radiological guidance is a novel technique and appears to be a simple, safe, effective and inexpensive method for treating rectal anastomotic stenoses.

Influence of patient age on normalized effective doses calculated for CT examinations

Monte Carlo simulations of CT examinations have been performed to estimate effective doses, normalized to axial air kerma, for six mathematical phantoms representing ages from newborn to adult, and for three CT scanner models covering a range of designs. Organ doses were calculated for CT exposures of contiguous, 1 cm wide, transverse slices in each phantom and summed to give normalized effective doses for scans of four regions of the trunk and head. In all cases an inverse trend is observed between normalized effective dose and phantom age, with the dose to the newborn from head and neck scans being 2.2-2.5 times higher than that to the adult, depending on scanner model. Corresponding increases for scans of the trunk region are more variable between scanners and range from a factor of 1.3 to 2.4. If typical clinical exposure conditions for adults are also utilized for children, then, for example, the effective dose to the newborn from a chest scan could be above 15 mSv. It is concluded that CT has the potential to deliver significantly greater radiation doses to children than to adults and in view of their greater susceptibility to radiation effects, special efforts should be made in clinical practice to reduce doses to children by the use of size-specific scan protocols.

Uncertainties in dose coefficients for intakes of tritiated water and organically bound forms of tritium by members of the public

The International Commission on Radiological Protection (ICRP) provides models for the calculation of doses from intakes of radionuclides, including intakes of tritium as tritiated water (HTO) or organically bound tritium (OBT). The ICRP models for HTO and OBT are explained and the assumptions made are examined. The reliability of dose estimates is assessed in terms of uncertainties in central estimates for population groups. The models consider intakes of HTO and OBT by ingestion and inhalation by adults and children and doses to the fetus following intakes by the mother. The analysis includes uncertainties in the absorption of OBT to blood, incorporation of tritium into OBT in body tissues, retention times in tissues, transfer to the fetus and the relative biological effectiveness (RBE) of tritium beta emissions compared with gamma rays. Heterogeneity of dose within tissues and cells is also considered. For intakes as HTO, dose is predominantly due to distribution and retention of HTO in body water and it was concluded that adult doses are reliable to within a factor of 2. For intakes of OBT, the extent of incorporation into OBT in body tissues results in greater uncertainties with estimates relying on animal data for selected compounds. The analysis indicated that adult doses from OBT can be considered to be known to within a factor of 3. Greater uncertainties in estimated doses for children and for in utero exposures were considered. Central values from the uncertainty analyses of doses for HTO and OBT were greater than the corresponding ICRP dose coefficients by about a factor of 2, mainly due to the inclusion of uncertainties in RBE for tritium. A detailed assessment of doses using appropriate parameters and considering uncertainties would be of particular importance in situations where the dose may approach dose limits or constraints. For exposures to known forms of OBT, specific dose assessments may be required.

A high-resolution add-on in-lens attachment for scanning electron microscopes

A compact add-on objective lens for the scanning electron microscope (SEM) has been designed and tested. The lens is < 35 mm high and can be fitted on to the specimen stage as an easy-to-use attachment. Initial results show that it typically improves the spatial resolution of the SEM by a factor of three. The add-on unit is based upon a permanent magnet immersion lens design. Apart from the extra attachment to the specimen stage, the SEM with the add-on lens functions in the normal way. The in-lens unit can comfortably accommodate specimen heights up to 10 mm. The new add-on lens unit opens up the possibility of operating existing SEMs in the high-resolution in-lens mode. By using a deflector at the top of the add-on lens unit, it can also operate as a quantitative multichannel voltage contrast spectrometer, capable of recording the energy spectrum of the emitted secondary electrons. Initial experiments confirm that a significant amount of voltage contrast can be obtained.

Simplified organ retention functions for physiologically based recycling biokinetic models

Recent ICRP Publications on biokinetic models show a movement from simple schematic models to more complex, physiologically-based models. Such models require considerably greater computing resources to implement than their predecessors, effectively making them inaccessible to many users. Fortunately, retention in most of the compartments of these large recycling models can be adequately approximated by the sum of a few exponential functions compatible with the simple catenary models used almost exclusively in ICRP Publication 30. An eigenvalue method is used to solve the plutonium model of ICRP Publication 67 for intakes by inhalation, ingestion, and injection. The organ retention expressions so obtained are reduced by least squares minimization to functions consisting of the sum of a few exponential terms only. These simplified functions give committed doses accurate to within 5% and activities to within 10%. A similar treatment is used to obtain simplified expressions for daily excretion rates of plutonium.