In this study the uptake performances of the naturally occurring zeolite, clinoptilolite, and of New Zealand mordenite are compared. The uptake of fully ionised ammonium ion from aqueous solutions in ...the concentration range 0–200
mg/l on to these two materials was compared. The influence of other cations present in water upon the ammonia uptake was also determined. The cations studied were potassium, calcium and magnesium. In all cases the anionic counterion present was chloride. The results showed that the mordenite exhibited higher overall uptake concentrations at equilibrium compared with clinoptilolite at solution concentrations greater than 80
mg/l. Beyond this value, the difference in solid-phase equilibrium concentrations on the mordenite became greater at higher solution-phase ammonium ion concentrations. The effect of the other cations upon uptake of ammonium ion was relatively small. In all cases, the ammonium ion showed the highest uptake on to both the mordenite and the clinoptilolite. In the case of clinoptilolite this was rather an unexpected result since the majority of other work shows clinoptilolite exhibiting a higher affinity for potassium ion compared with ammonium ion. This may be explained by the fact that the clinoptilolite came from volcanic deposits in New Zealand. This is the first such study on this material. At solution-phase equilibrium concentrations of greater than 80
mg/l, the mordenite showed smaller reductions in ammonium ion uptake in the presence of the other cations when compared with clinoptilolite.
The removal of ammonium ion from wastewater is an important part of tertiary wastewater treatment and is increasingly necessary to meet drinking water and discharge standards being applied in much of ...the developed world. The use of nitrification filters is an established technology which involves the biological oxidation of ammonium ion to the more benign nitrate ion. An alternative technique for ammonia removal is the use of ion-exchange however the capital costs can be significant and the economics of chemical regeneration may be prohibitive for large volume applications. In this paper we examine the combination of nitrification and ion-exchange in a packed bed system using the natural zeolitic ion-exchangers, clinoptilolite, and mordenite on which colonies of nitrifying bacteria are cultivated. The combined system intensifies ammonia removal and offers the possibility in principle of a more robust technique less sensitive to rapid perturbations in ammonia concentration and less costly than in a single ion-exchange process. One limitation of this approach is the rapid consumption of oxygen in the biologically active column. The paper demonstrates a novel technique for enhancing the oxygen concentration in a combined ion-exchange and nitrification packed column. The performance of fixed beds of clinoptilolite and mordenite in the presence of nitrifying bacteria is compared to that in columns in which only ion-exchange is occurring. Two modes of aeration are compared: (1) external aeration in which the feedwater is aerated conventionally by gas bubbling; (2) in situ aeration in which a membrane-aeration unit is incorporated into the packed bed. The ammonia removal in the presence of the nitrifiers is significantly intensified. Both methods of aeration provided a comparable further enhancement. In the case of the membrane system the air consumption was reduced by a factor of 60.
Regarding geographical distribution and clinical relevance, the most common canine geohelminths are
, ancylostomatids, and
. Canine intestinal parasites from the soil and sand present an important ...potential serious human health hazard, especially for the children preschool and school – age. This paper aimed to establish the degree of contamination of soil and sand with zoonotic parasites from the canine feces and the degree of risk they could pose for human health in public places and playgrounds in the city of Niš. Our parasitological study involved 200 soil samples and 50 sand samples from the public parks in the city of Niš in southeastern Serbia (43°19′15″N, 21°53′45″ E). From several locations, about 100 g of soil and sand was collected based on the bioclimatic indices. Parasitological diagnosis was performed using conventional qualitative and quantitative coprological methods, abiding by the recommendations about the diagnosis of parasitic diseases. In 38 – 46 % of soil samples and 40 % of sand samples seven species of endoparasites were diagnosed. In the samples of soil, a medium and high degree of contamination with the ascarid
(14 – 22 %) was detected, as well as a low and medium degree of contamination with ancylostomatids (4 – 12 %), and in the samples of sand, a variable degree of contamination with the helminths
(26 %) and
(16 %) was found. A statistically significant difference was found in the contamination with
eggs between the samples of sand and samples of soil. The studied public surfaces represent the reservoir of zoonotic parasites, which is a public health problem requiring a synergistic action of several factors to be successfully resolved, i.e. the implementation of prevention, surveillance, and control measures.
In this correspondence, a new method for improving hard-decision bit-flipping decoding of low-density parity-check (LDPC) codes is presented. Bits with a number of unsatisfied check sums larger than ...a predetermined threshold are flipped with a probability p /spl les/ 1 which is independent of the code considered. The probability p is incremented during decoding according to some rule. With a proper choice of the initial p, the proposed improved bit-flipping (BF) algorithm achieves gain not only in performance, but also in average decoding time for signal-to-noise ratio (SNR) values of interest with respect to p = 1.
A generalized low-density parity check code (GLDPC) is a low-density parity check code in which the constraint nodes of the code graph are block codes, rather than single parity checks. In this ...paper, we study GLDPC codes which have BCH or Reed-Solomon codes as subcodes under bounded distance decoding (BDD). The performance of the proposed scheme is investigated in the limit case of an infinite length (cycle free) code used over a binary erasure channel (BEC) and the corresponding thresholds for iterative decoding are derived. The performance of the proposed scheme for finite code lengths over a BEC is investigated as well. Structures responsible for decoding failures are defined and a theoretical analysis over the ensemble of GLDPC codes which yields exact bit and block error rates of the ensemble average is derived. Unfortunately this study shows that GLDPC codes do not compare favorably with their LDPC counterpart over the BEC. Fortunately, it is also shown that under certain conditions, objects identified in the analysis of GLDPC codes over a BEC and the corresponding theoretical results remain useful to derive tight lower bounds on the performance of GLDPC codes over a binary symmetric channel (BSC). Simulation results show that the proposed method yields competitive performance with a good decoding complexity trade-off for the BSC.
This letter presents a systematic and recursive method to construct good low-density parity-check (LDPC) codes, especially those with high rate. The proposed method uses a parity check matrix of a ...quasi-cyclic LDPC code with given row and column weights as a core upon which the larger code is recursively constructed with extensive use of pseudorandom permutation matrices. This construction preserves the minimum distance and girth properties of the core matrix and can generate either regular, or irregular LDPC codes. The method provides a unique representation of the code in compact notation.
In Serbia, in most cases, small family outbreaks of trichinellosis occur due to the consumption of untested infected meat from domestic pigs that are raised and slaughtered in the backyards of small ...individual farms. The aim of this study is to present data regarding 24 patients involved in two outbreaks that occurred in two neighbouring districts in Serbia during a closely related period of time in August 2014. The source of infection in the first outbreak was undercooked pork, while raw pork sausages caused the second outbreak. Meat samples and sausages were Trichinella spp. positive by artificial digestion. With the aim to obtain a second opinion and validate the serological findings discovered at the Public Health Institute Nis, all samples were sent to the National Reference Laboratory for Trichinellosis, INEP. Serodiagnosis showed that 21 persons were positive (87.5%) and three (12.5%) were negative for anti-Trichinella antibodies, while 15 patients fulfilled the trichinellosis case definition. Western blot analysis (using an epitope unique for the muscle larvae stage of the Trichinella genus) confirmed the diagnosis of trichinellosis in five patients. Six patients also had specific antibodies against Toxocara canis (T. canis). Due to the fact that in endemic foci in Serbia there is the presence of Trichinella spiralis and T. canis and that these two infections could be asymptomatic, we consider that trichinellosis cases were irrefutably proven. The dilemma about the existence of co-infection with T. canis remained open due to the lack of clinical findings.
Summary
Human dirofilariosis is a relatively rare infection caused by filarial worms of the genus Dirofilaria. We herein report the first case of human subcutaneous dirofilariosis in the southeastern ...part of Serbia. A complete alive nematode was removed from a nodule in the periorbital region of a 50‐year‐old woman. The nematode was morphologically identified as a D. repens‐like immature female. The diagnosis was confirmed with molecular methods. The patient was probably infected in the South‐East Serbia as she had not travelled abroad, nor in other parts of Serbia such as Vojvodina, recently identified as a hyperendemic area for D. repens infection of dogs.
We report here a specimen of the horsehair worm (Gordiida, Nematomorpha)
(
) found in a patient´s urine. This is the first record of this species from Serbia and the sixth gordiid species known in ...Serbia. It is discussed that there is no evidence that gordiids are parasites of humans. Instead, gordiids parasitize terrestrial insects, which release their mature gordiid parasite into water and may thereby also use containers in human surroundings. Pseudoparasites, such as
, do not pose a threat to human health nor are they a serious public health issue.
Infection with parasites from the Trichinella genus occurs in many vertebrates but disease only occurs in humans (trichinellosis). Humans are infected after the consumption of raw or undercooked meat ...from infected wild or domestic animals (usually swine or horses). Using the monoclonal antibody (mAb) 7C2C5, specific for an epitope unique to the muscle larvae of the genus Trichinella, we have developed a competitive enzyme-linked immunosorbent assay (c-ELISA) that enables the rapid detection of Trichinella-specific antibodies in sera originating from two different host species (human, swine) infected with either Trichinella spiralis or Trichinella britovi. This novel c-ELISA exhibited 100% specificity and sensitivity, as confirmed by a Western blot test. The assay is easy to use (one incubation step), and the time required for the procedure (45 min) is shorter than in any other ELISA format. This test could be useful for both the detection and surveillance of Trichinella infections.
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