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1.
J Intellect Disabil Res ; 67(12): 1336-1353, 2023 12.
Article in English | MEDLINE | ID: mdl-36788023

ABSTRACT

BACKGROUND: Children around the world, particularly those with intellectual disabilities (ID), are exhibiting poor motor skill proficiency. Compared with typically developing children (TDC), children with intellectual disabilities (CwID) are 65% more likely to exhibit low levels of motor competence. The purpose of this meta-analysis was to compare the motor skill proficiency levels, in terms of fundamental movement skills (FMS) of CwID to TDC. FMS are the building blocks required for lifelong participation in sport and physical activity. METHOD: The meta-analysis was conducted according to PRISMA statement guidelines. 6 electronic databases were searched and 16, 679 studies were found. A total of 26 studies (total participants n = 3,525) met the inclusion criteria. A multivariate maximum likelihood multivariate random effects model was fitted to the data using the metafor package in R. RESULTS: The study showed that the standardised mean difference (Hedges' g) in FMS between TDC and CwID is large (g = 1.24; CI 95% [.87, 1.62]). Specifically, significant differences between the two groups emerged in all five outcomes: (1) total locomotor score, (2) total object manipulation score, (3) balance, (4) run skill and (5) throw skill. CONCLUSIONS: Further investigation into effective intervention strategies is required in order to reduce the magnitude of difference in motor skill proficiency between the two groups. In addition to developing, implementing and evaluating these interventions, researchers need to work hand in hand with national governing bodies (NGB) of sport and policy makers to ensure that teachers and coaches are being provided with opportunities to upskill in the area of FMS.


Subject(s)
Intellectual Disability , Child , Humans , Movement , Motor Skills , Child Development , Exercise
2.
Eur J Orthop Surg Traumatol ; 33(4): 1411-1420, 2023 May.
Article in English | MEDLINE | ID: mdl-35701554

ABSTRACT

PURPOSE: Treatment of secondary knee osteoarthritis with a significant extra-articular deformity can be challenging. In such cases, an osteotomy or a custom-made hinged knee arthroplasy (CMH) are treatment options. However, there are limited data on the outcomes of using CMHs. Thus, the aim of this retrospective study was to assess the clinical results and subjective outcomes of CMHs. METHODS: We reviewed 9 CMHs (Endo-Model, LINK) in 7 patients with a minimum of 2-year follow-up. Upon the last follow-up, we evaluated MA, stability and range of movement (ROM). Oxford Knee Score (OKS) was used to evaluate patient-reported outcomes. RESULTS: The average age upon surgery was 61 years (48-76 years), and the follow-up period was 66 months. There were no early complications. Two CMHs were revised, one due to aseptic loosening and one due to late-onset haematogenic infection. Pre-operatively, MA varied from 18° (average 11°) valgus-deformity to 30° (average 17°) varus-deformity. Post-operatively, 7/9 (78%) of patients achieved better MA. Upon follow-up, the average OKS was 41/48, and ROM was 113°. CONCLUSIONS: Patients treated with CMHs achieved good clinical and patient-reported outcomes. There were no early reoperations, and revision rate was relatively low. Overall, CMH could be considered for low-demand patients with increased operative risks.


Subject(s)
Arthroplasty, Replacement, Knee , Knee Prosthesis , Osteoarthritis, Knee , Humans , Middle Aged , Osteoarthritis, Knee/surgery , Retrospective Studies , Range of Motion, Articular , Arthroplasty, Replacement, Knee/adverse effects , Knee Joint/surgery
3.
Eur Cell Mater ; 38: 35-50, 2019 08 05.
Article in English | MEDLINE | ID: mdl-31381126

ABSTRACT

Most synthetic bone grafts are either hard and brittle ceramics or paste-like materials that differ in applicability from the gold standard autologous bone graft, which restricts their widespread use. Therefore, the aim of the study was to develop an elastic, highly porous and biodegradable ß-tricalciumphosphate/poly(L-lactide-co-ε-caprolactone) (ß-TCP/PLCL) composite for bone applications using supercritical CO2 foaming. Ability to support osteogenic differentiation was tested in human adipose stem cell (hASC) culture for 21 d. Biocompatibility was evaluated for 24 weeks in a rabbit femur-defect model. Foamed composites had a high ceramic content (50 wt%) and porosity (65-67 %). After 50 % compression, in an aqueous environment at 37 °C, tested samples returned to 95 % of their original height. Hydrolytic degradation of ß-TCP/PLCL composite, during the 24-week follow-up, was very similar to that of porous PLCL scaffold both in vitro and in vivo. Osteogenic differentiation of hASCs was demonstrated by alkaline phosphatase activity analysis, alizarin red staining, soluble collagen analysis, immunocytochemical staining and qRT-PCR. In vitro, hASCs formed a pronounced mineralised collagen matrix. A rabbit femur defect model confirmed biocompatibility of the composite. According to histological Masson-Goldner's trichrome staining and micro-computed tomography, ß-TCP/PLCL composite did not elicit infection, formation of fibrous capsule or cysts. Finally, native bone tissue at 4 weeks was already able to grow on and in the ß-TCP/PLCL composite. The elastic and highly porous ß-TCP/PLCL composite is a promising bone substitute because it is osteoconductive and easy-to-use and mould intraoperatively.


Subject(s)
Calcium Phosphates/chemistry , Osteogenesis , Polyesters/chemistry , Tissue Scaffolds/chemistry , Adipose Tissue/cytology , Alkaline Phosphatase/metabolism , Animals , Carbon Dioxide/chemistry , Cell Differentiation , Cells, Cultured , Collagen/metabolism , Compressive Strength , Elasticity , Mesenchymal Stem Cell Transplantation/methods , Mesenchymal Stem Cells/cytology , Mesenchymal Stem Cells/metabolism , Osteoblasts/cytology , Porosity , Rabbits , Tissue Scaffolds/adverse effects
4.
Scand J Surg ; 106(3): 278-282, 2017 Sep.
Article in English | MEDLINE | ID: mdl-27550244

ABSTRACT

BACKGROUND: Flexor tendon injuries cause significant morbidity in working-age population. The epidemiology of these injuries in adult population is not well known. The aim of this study was to describe the epidemiology of flexor tendon injuries in a Northern Finnish population. MATERIAL AND METHODS: Data on flexor tendon injuries, from 2004 to 2010, were retrieved from patient records from four hospitals, which offer surgical repair of the flexor tendon injuries in a well-defined area in Northern Finland. The incidence of flexor tendon injury as well as the gender-specific incidence rates was calculated. Mechanism of injury, concomitant nerve injuries, and re-operations were also recorded. RESULTS: The incidence rate of flexor tendon injury was 7.0/100,000 person-years. The incidence was higher in men and inversely related to age. The most common finger to be affected was the fifth digit. In 37% of injuries also digital nerve was affected. The most common finger to have simultaneous digital nerve injury was the thumb. CONCLUSION: Flexor tendon laceration is a relatively rare injury. It predominantly affects working-aged young males and frequently includes a nerve injury, which requires microsurgical skills from the surgeon performing the repair. This study describes epidemiology of flexor tendon injuries and therefore helps planning the surgical and rehabilitation services needed to address this entity.


Subject(s)
Hand Injuries/epidemiology , Tendon Injuries/epidemiology , Adolescent , Adult , Aged , Female , Finland/epidemiology , Hand Injuries/surgery , Humans , Incidence , Male , Middle Aged , Multiple Trauma/epidemiology , Multiple Trauma/surgery , Neurosurgical Procedures , Orthopedic Procedures , Peripheral Nerve Injuries/epidemiology , Peripheral Nerve Injuries/surgery , Retrospective Studies , Tendon Injuries/surgery , Young Adult
5.
Eur Psychiatry ; 30(6): 750-5, 2015 Sep.
Article in English | MEDLINE | ID: mdl-26117381

ABSTRACT

OBJECTIVE: To increase knowledge on the reproductive health of women who have been placed in a residential school, a child welfare facility for adolescents with severe psychosocial problems. METHODS: All women (n=291) who lived in the Finnish residential schools on the last day of the years 1991, 1996, 2001 and 2006 were included in this study and compared with matched general population controls. Register-based information on induced abortions and births was collected until the end of the year 2011. RESULTS: Compared to controls, women with a residential school history had more induced abortions. A higher proportion of their births took place when they were teenagers or even minors. They were more often single, smoked significantly more during pregnancy and had a higher risk of having a preterm birth or a baby with a low birth weight. CONCLUSIONS: The findings have implications for the planning of preventive and supportive interventions that aim to increase the well-being of women with a residential school history and their offspring.


Subject(s)
Abortion, Induced , Pregnancy in Adolescence , Premature Birth , Social Problems , Abortion, Induced/psychology , Abortion, Induced/statistics & numerical data , Adolescent , Cohort Studies , Education, Special/methods , Female , Finland/epidemiology , Humans , Infant, Low Birth Weight , Needs Assessment , Pregnancy , Pregnancy in Adolescence/psychology , Pregnancy in Adolescence/statistics & numerical data , Premature Birth/epidemiology , Premature Birth/etiology , Premature Birth/psychology , Psychology , Retrospective Studies , Social Problems/psychology , Social Problems/statistics & numerical data
6.
Community Dent Health ; 29(2): 149-53, 2012 Jun.
Article in English | MEDLINE | ID: mdl-22779376

ABSTRACT

INTERVENTIONS: In 2007, the Finnish National Board of Education (FNBE) and the National Public Health Institute (KTL) recommended to schools that they quit regular selling of candies and soft drinks. OBJECTIVE: The aim of this study was to determine how and why such selling changed from 2007 to 2008 after the national recommendation. METHODS: Surveys were conducted using online questionnaires to all upper comprehensive schools in Finland. In 2007, 480 (49%) and in 2008, 507 (51%) schools answered the questionnaire; 319 (32%) schools participated in both studies. Schools were asked whether they sold candies, soft drinks or other sweet products and, if theyhad changed the selling of these products, why. The changes in selling were analyzed by using McNemar's test. RESULTS: Of the responding schools, 56% (n=267) and 46% (n=233) sold sweet products in 2007 and 2008, respectively. Of the schools responding both years, 56% reported selling sweet products in 2007 and 50% in 2008. Selling had decreased by 11% among the schools that took part in both studies. The main reasons stated for quitting selling these products were concern about pupils' health (40%) and the recommendation of the FNBE and KTL (38%). CONCLUSIONS: The national recommendation was followed by some decrease in sale of sweet products. For further progress, new actions, both policy measures and broader public involvement, may be needed.


Subject(s)
Candy/statistics & numerical data , Commerce/statistics & numerical data , Guidelines as Topic , Schools , Adolescent , Carbonated Beverages , Dietary Sucrose/classification , Feeding Behavior , Finland , Food Services/statistics & numerical data , Health Promotion , Humans , Nutrition Policy
7.
Res Vet Sci ; 90(2): 301-5, 2011 Apr.
Article in English | MEDLINE | ID: mdl-20598330

ABSTRACT

Monocarboxylate transporter 1 (MCT 1) necessary for the absorption of short chain fatty acids in the gastrointestinal tract, was measured in ventral wall of rumen, abomasum and duodenum of kids at age of 1 day and 1, 2 and 8 weeks. Samples from rumen, abomasum and duodenum were also taken from finishing beef bulls fed concentrate either ad libitum (A) or restrictively (R). Increased expression of MCT 1 was observed during the first week and parallel increases were found in its ancillary protein, CD147 in the rumen of kids. In duodenum, MCT 1 decreased with age and a similar tendency was seen in abomasum. In bulls, MCT 1 was higher in ventral wall and atrium than in other parts of gastrointestinal tract. However, in ventral wall of rumen MCT 1 was higher in A than in R. These findings show that MCT 1 increases with the development of rumen function and also in adult animals MCT 1 may change with the feeding.


Subject(s)
Aging , Basigin/metabolism , Cattle/metabolism , Gastrointestinal Tract/metabolism , Goats/metabolism , Monocarboxylic Acid Transporters/metabolism , Symporters/metabolism , Animal Feed , Animals , Basigin/genetics , Cattle/growth & development , Diet/veterinary , Gene Expression Regulation/physiology , Goats/growth & development , Male , Monocarboxylic Acid Transporters/genetics , Symporters/genetics
8.
J Phys Condens Matter ; 22(1): 015601, 2010 Jan 13.
Article in English | MEDLINE | ID: mdl-21386230

ABSTRACT

Validity of the Landauer-Buttiker formalism for studying linear transport in mesoscopic systems is well established theoretically as well as experimentally. Akkermans et al (1991 Phys. Rev. Lett. 66 76) have shown that the formalism can be extended to study thermodynamic properties like persistent currents. This extension was verified for simple one-dimensional systems. We study the applicability of Akkermans et al' s formula for quasi-one-dimensional systems with several conducting channels. In the case that all modes are propagating the formula is still valid but in the case of evanescent modes it requires reinterpretation.

9.
Mol Psychiatry ; 15(3): 308-18, 2010 Mar.
Article in English | MEDLINE | ID: mdl-18645571

ABSTRACT

Proton magnetic resonance spectroscopy ((1)H MRS) neurometabolite abnormalities have been detected widely in subjects with and at risk for schizophrenia. We hypothesized that such abnormalities would be present both in patients with schizophrenia and in their unaffected twin siblings. We acquired magnetic resonance spectra (TR/TE=3000/30 ms) at voxels in the mesial prefrontal gray matter, left prefrontal white matter and left hippocampus in 14 twin pairs discordant for schizophrenia (2 monozygotic, 12 dizygotic), 13 healthy twin pairs (4 monozygotic, 9 dizygotic) and 1 additional unaffected co-twin of a schizophrenia proband. In the mesial prefrontal gray matter voxel, N-acetylaspartate (NAA), creatine+phosphocreatine (Cr), glycerophosphocholine+phosphocholine (Cho) and myo-inositol (mI) did not differ significantly between patients with schizophrenia, their unaffected co-twins or healthy controls. However, glutamate (Glu) was significantly lower in patients with schizophrenia (31%, percent difference) and unaffected co-twins (21%) than in healthy controls (collapsed across twin pairs). In the left hippocampus voxel, levels of NAA (23%), Cr (22%) and Cho (36%) were higher in schizophrenia patients compared with controls. Hippocampal NAA (25%), Cr (22%) and Cho (37%) were also significantly higher in patients than in their unaffected co-twins. Region-to-region differences in metabolite levels were also notable within all three diagnosis groups. These findings suggest that (1)H MRS neurometabolite abnormalities are present not only in patients with schizophrenia, but also in their unaffected co-twins. Thus, reduced mesial prefrontal cortical Glu and elevated hippocampal NAA, Cr and Cho may represent trait markers of schizophrenia risk and, when exacerbated, state markers of schizophrenia itself.


Subject(s)
Magnetic Resonance Spectroscopy/methods , Schizophrenia/metabolism , Twins, Dizygotic/metabolism , Twins, Monozygotic/metabolism , Aspartic Acid/analogs & derivatives , Creatine/metabolism , Female , Glutamic Acid/metabolism , Glycerylphosphorylcholine/metabolism , Hippocampus/metabolism , Humans , Inositol/metabolism , Male , Middle Aged , Nerve Fibers, Myelinated/metabolism , Nerve Fibers, Unmyelinated/metabolism , Phosphocreatine/metabolism , Phosphorylcholine/metabolism , Prefrontal Cortex/metabolism , Protons , Schizophrenia/diagnosis , Twins, Dizygotic/psychology , Twins, Monozygotic/psychology
10.
Phys Rev Lett ; 102(24): 245302, 2009 Jun 19.
Article in English | MEDLINE | ID: mdl-19659022

ABSTRACT

The growth rates of the (110) and (100) facets on bcc (3)He crystals have been measured near the magnetic ordering transition at T_{N} = 0.93 mK. In the ordered phase, we have observed several growth modes which correspond to different values of the step energy. We show that, because of quantum delocalization, the step induces a cluster of ferromagnetically ordered nuclear spins. The free energy of such a cluster is relatively large and depends on the orientation of the underlying antiferromagnetic domain. In the paramagnetic phase, the mobilities of the basic facets are greatly reduced because of the much slower spin diffusion in the bulk solid.

11.
Phys Rev Lett ; 102(10): 106102, 2009 Mar 13.
Article in English | MEDLINE | ID: mdl-19392129

ABSTRACT

We demonstrate, via scanning tunneling microscopy (STM) measurements performed at 48 K, the existence of "bright beaches" at the edges of K islands (diameter approximately 5-500 nm) on the graphite surface. The enhanced tunneling current is only observed in monolayer-high islands on graphite, and not in islands of similar geometry on top of a K monolayer film. First-principles density functional calculations and STM simulations suggest that this is an STM field effect, which appears as the positive tip attracts donated electrons back to the metallic K islands. The restored charge accumulates preferentially at the island edges.

12.
Phys Rev Lett ; 101(25): 255302, 2008 Dec 19.
Article in English | MEDLINE | ID: mdl-19113721

ABSTRACT

According to Landau, at T=0 the equilibrium crystal surface consists of an infinite number of facets lying in all directions with rational Miller indices-the so-called devil's staircase phenomenon. We have discovered 11 new types of facets on the surface of 4He crystals, in addition to the three observed before. Some of the new facets are of very high order, lying at angles as small as 4 degrees to the basal c facet, thus forming the predicted devil's staircase. The estimated step energies depend rather weakly on interplanar distance which we explain by the strong anisotropy of the steps.

13.
J Med Genet ; 44(9): 570-8, 2007 Sep.
Article in English | MEDLINE | ID: mdl-17513527

ABSTRACT

BACKGROUND: Age-related hearing impairment (ARHI) is the most common sensory impairment in older people, affecting 50% of those aged 80 years. The proportion of older people is increasing in the general population, and as a consequence, the number of people affected with ARHI is growing. ARHI is a complex disorder, with both environmental and genetic factors contributing to the disease. The first studies to elucidate these genetic factors were recently performed, resulting in the identification of the first two susceptibility genes for ARHI, NAT2 and KCNQ4. METHODS: In the present study, the association between ARHI and polymorphisms in genes that contribute to the defence against reactive oxygen species, including GSTT1, GSTM1 and NAT2, was tested. Samples originated from seven different countries and were combined into two test population samples, the general European population and the Finnish population. Two distinct phenotypes for ARHI were studied, Z(low) and Z(high), representing hearing in the low and high frequencies, respectively. Statistical analysis was performed for single polymorphisms (GSTM1, GSTT1, NAT2*5A, NAT2*6A, and NAT2*7A), haplotypes, and gene-environment and gene-gene interactions. RESULTS: We found an association between ARHI and GSTT1 and GSTM1 in the Finnish population sample, and with NAT2*6A in the general European population sample. The latter finding replicates previously published data. CONCLUSION: As replication is considered the ultimate proof of true associations in the study of complex disorders, this study provides further support for the involvement of NAT2*6A in ARHI.


Subject(s)
Arylamine N-Acetyltransferase/genetics , Hearing Disorders/genetics , Polymorphism, Single Nucleotide , Age of Onset , Aged , Arylamine N-Acetyltransferase/physiology , Environment , Epistasis, Genetic , Europe/epidemiology , Female , Finland/epidemiology , Gene Frequency , Glutathione Transferase/genetics , Glutathione Transferase/physiology , Haplotypes/genetics , Hearing Disorders/epidemiology , Hearing Loss, High-Frequency/epidemiology , Hearing Loss, High-Frequency/genetics , Humans , Male , Middle Aged , Oxidative Stress/genetics
14.
Arch Orthop Trauma Surg ; 127(5): 349-53, 2007 Jul.
Article in English | MEDLINE | ID: mdl-17333221

ABSTRACT

INTRODUCTION: The treatment of fractures of the distal third of the tibia remains still controversial. It is often difficult to get and retain good reduction by non-operative or nailing methods. Open reduction and plate fixation offers good reduction and retention of the achieved position. However, increased soft tissue damage and high complication rate has led to search less invasive surgical methods such as minimal invasive plating technique. MATERIAL AND METHODS: Lateral approach for the distal tibia allows to reduce and to plate both the fibula and the tibia using only one skin incision. We have used lateral approach for 20 consecutive tibia fracture patients and report clinical and radiological results after an average follow-up of 31 months. RESULTS: All fractures united, but two malunions were developed after good primary reduction. Seventeen patients achieved excellent or good subjective result while one had moderate and two poor results. Four superficial wound infections were noticed and they were treated conservatively. CONCLUSION: We conclude that lateral approach for the distal tibia is a demanding, but useful surgical method for treatment of the distal tibia fractures especially in cases where no medial comminution of the tibia is present and when the fibula has to be fixed, too.


Subject(s)
Fracture Fixation, Internal/methods , Tibial Fractures/surgery , Adolescent , Adult , Aged , Bone Plates , Bone Transplantation , Female , Fibula/injuries , Fibula/surgery , Follow-Up Studies , Fracture Healing , Humans , Male , Middle Aged , Patient Satisfaction , Treatment Outcome
15.
B-ENT ; 3 Suppl 7: 51-60, 2007.
Article in English | MEDLINE | ID: mdl-18225608

ABSTRACT

INTRODUCTION AND AIM: Tinnitus is a common condition affecting approximately 20% of the older population. There is increasing evidence that changes in the central auditory system following cochlear malfunctioning are responsible for tinnitus. To date, few investigators have studied the influence of genetic factors on tinnitus. The present report investigates the presence of a familial effect in tinnitus subjects. METHODS: In a European multicentre study, 198 families were recruited in seven European countries. Each family had at least 3 siblings. Subjects were screened for causes of hearing loss other than presbyacusis by clinical examination and a questionnaire. The presence of tinnitus was evaluated with the question "Nowadays, do you ever get noises in your head or ear (tinnitus) which usually last longer than five minutes". Familial aggregation was tested using three methods: a mixed model approach, calculating familial correlations, and estimating the risk of a subject having tinnitus if the disorder is present in another family member. RESULTS: All methods demonstrated a significant familial effect for tinnitus. The effect persisted after correction for the effect of other risk factors such as hearing loss, gender and age. The size of the familial effect is smaller than that for age-related hearing impairment, with a familial correlation of 0.15. CONCLUSION: The presence of a familial effect for tinnitus opens the door to specific studies that can determine whether this effect is due to a shared familial environment or the involvement of genetic factors. Subsequent association studies may result in the identification of the factors responsible. In addition, more emphasis should be placed on the effect of role models in the treatment of tinnitus.


Subject(s)
Family , Genetic Predisposition to Disease , Tinnitus/genetics , Aged , Europe/epidemiology , Female , Humans , Male , Middle Aged , Prevalence , Risk Factors , Surveys and Questionnaires , Tinnitus/epidemiology
16.
J Phys Condens Matter ; 19(7): 076211, 2007 Feb 21.
Article in English | MEDLINE | ID: mdl-22251598

ABSTRACT

The exact diagonalization technique is used to study many-particle properties of interacting electrons with spin, confined in a two-dimensional harmonic potential. The single-particle basis is limited to the lowest Landau level. The results are analysed as a function of the total angular momentum of the system. Only at angular momenta corresponding to the filling factors 1, 1/3, 1/5, etc is the system fully polarized. The lowest energy states exhibit spin waves, domains, and localization, depending on the angular momentum. Vortices exist only at excited polarized states. The high angular momentum limit shows localization of electrons and separation of the charge and spin excitations.

17.
Phys Rev Lett ; 94(10): 106405, 2005 Mar 18.
Article in English | MEDLINE | ID: mdl-15783501

ABSTRACT

In a quantum-mechanical system, particle-hole duality implies that instead of studying particles, we can get equivalent information by studying the missing particles, the so-called holes. Using this duality picture for fermions in a rotating trap the vortices appear as holes in the Fermi sea. Here we predict that the formation of vortices in quantum dots at high magnetic fields causes oscillations in the energy spectrum which can be experimentally observed using accurate tunneling spectroscopy. We use the duality picture to show that these oscillations are caused by the localization of vortices in rings.

18.
Phys Rev Lett ; 93(9): 090407, 2004 Aug 27.
Article in English | MEDLINE | ID: mdl-15447083

ABSTRACT

We show that the rotation of trapped quantum mechanical particles with a repulsive interaction can lead to vortex formation, irrespective of whether the particles are bosons or (unpaired) fermions. The exact many-particle wave function constitutes similar structures in both cases, implying that this vortex formation is indeed universal.

19.
Arch Environ Contam Toxicol ; 45(1): 1-10, 2003 Jul.
Article in English | MEDLINE | ID: mdl-12948168

ABSTRACT

The use of biological systems to remove contaminants from waste streams has been well documented. However, when dealing with complex waste streams, the use of one biological treatment system may not be the best alternative. When treating a complex waste stream, the use of "treatment trains" or "coupled systems" may be advantageous compared with any single biological technology. This article demonstrated that a coupled system was effective in biodegrading a chemically complex mixture of volatile organic compounds (VOCs). A bench-scale system consisting of a liquid bioreactor and a biofilter was used for the biodegradation of acetone, methanol, methyl ethyl ketone, naphthalene, alpha-pinene, and toluene. The bioreactor contained an inert solid support that immobilized a microbial population. The biofiltration portion of the system utilized the same microbial inoculum but employed Douglas fir bark as its solid support. Successful biodegradation of the complex VOC mixture was accomplished with this coupled system with an average VOC removal efficiency of 96% and VOC loading rates as high as 79 g/m3/h for inlet concentrations of > 8,000 ppmv. At elevated flow rates the liquid reactor demonstrated limited removal of some compounds, such as alpha-pinene and toluene, while maintaining excellent removal of other compounds, such as methanol and acetone. The biofilter portion of the system proved very successful in degrading the remaining toluene and alpha-pinene, thus complementing the removal from the bioreactor. This study demonstrates that coupled biological systems may be utilized for a chemically complex VOC-laden air stream that previously may not have been considered for biological treatment.


Subject(s)
Air Pollution/prevention & control , Biodegradation, Environmental , Filtration , Organic Chemicals/isolation & purification , Volatilization
20.
Phys Rev Lett ; 90(6): 066802, 2003 Feb 14.
Article in English | MEDLINE | ID: mdl-12633316

ABSTRACT

The magnetism of square lattices of quantum dots with up to 12 electrons per dot is studied using the spin-density functional formalism. At small values of the lattice constant, all lattices are nonmagnetic and gapless. When the lattice constant is increased, the shell structure of the single dots governs the magnetism of the lattice. At closed shells, the lattices are nonmagnetic and have a gap at the Fermi level. At the beginning and at the end of a shell, they become ferromagnetic and stay gapless up to large values of the lattice constant. Antiferromagnetism was observed only at midshell after a band gap was opened.

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