Porous ceramic monoliths based on diatomite Šaponjić, Aleksandra; Stanković, Miroslav; Majstorović, Jelena ...
Ceramics international,
09/2015, Letnik:
41, Številka:
8
Journal Article
Recenzirano
Porous silica ceramics were obtained at low forming pressure and low sintering temperature by using diatomaceous earth as a silica source and boric acid as an inexpensive additive. The starting raw ...material, diatomite from surface coal mine Kolubara, Serbia, was purified from organic and inorganic impurities by using heat and chemical treatment. Boric acid was used as binding and sintering aid up to 2wt%. Powder was compacted by using different pressures of 40, 60 and 80MPa. The pressed samples were sintered at 850, 1000, 1150, and 1300°C for 4h in air. A relatively high porosity in the range of 60–70% is obtained for the samples pressed at 40, 60 and 80MPa and sintered at 1000°C. Median pore size diameters are in the range of macroporous up to 2μm in the samples sintered at 1150 and 1300°C. X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scaning electron microscopy (SEM) and mercury porosimetry measurements were employed to characterize the phases, functional groups, microstructure and pore size distribution of the obtained samples. In addition, measurements of densities and open porosities by immersion technique, according to Archimedes principle, were used. The relations between mechanical properties (Young modulus, Poisson ratio, and compressive strength) versus content of boric acid in the investigated samples were studied and disscussed.
The structural and morphological properties of iron-doped mullite powders are the subject of the present study. The powders of undoped and iron-doped mullite in the composition range of 3–15 wt% ...Fe2O3 were synthesized by a combination of sol-gel and combustion methods. The excess of water and urea were introduced in reaction solutions to enhance the copolymerization of aluminum and silicon species. The results of structural characterization revealed that the synthesized mullite powders were amorphous of a hybrid type. The specific surface area of the undoped mullite powder was 262 m2 g-1 with a maximum pore radius (dp) of 2 nm classifying it into mesoporous materials. The addition of iron has reduced the specific surface area, while the pore size value remained the same except for the sample with 3 wt% Fe2O3 (SBET = 278 m2 g-1; dp = 3 nm). The presence of iron caused lowering the temperature of liquid phase formation, while present urea combusted providing the increase of the temperature locally that caused the sintering and formation of agglomerates of smaller particles. However, the results of the particle size analysis are not straightforward. The values of mean volume diameter (D3,4) indicated that the particle size increased to 6 wt% Fe2O3 (123.6 μm), and then decreased and for the sample with 12 wt% Fe2O3, it was equal to 96.6 μm. Thus, the added iron contributed to the more uniform particle size distribution. The SEM analysis has also shown the coarse powder particles consisted of the coalesced smaller particles.
: In patients with colorectal cancer (CRC), heterogeneous expression of Mismatch repair (MMR) proteins can manifest itself in several different forms and is not such a rare phenomenon. Therefore, it ...is very important to recognize the nuclear expression of MMR proteins of different MMR status in order to avoid false positive or false negative results. The aim of this study was to determine the frequency and distribution of heterogeneous expression of MMR proteins in patients with stages II and III of the disease as well as its association with clinical, demographic and pathological characteristics of CRC in relation to proficient and deficient expression of MMR proteins.
: The study included 104 cases of colorectal cancer obtained from surgical colectomy material in stages II and III of the disease.
From a total of 104 patients with colorectal cancer, immunohistochemical analysis of the expression of all four MMR proteins showed that heterogeneous expression of MMR proteins (as well as deficient immunoreactivity of tumor cells) was present in 12 cases, while proficient expression of MMR proteins was detected in 80 tumors.
: Our study showed that the only independent predictors of the loss of MMR protein expression were younger patient age and right-sided anatomical location of the tumor. The study also established the existence of heterogeneous expression of MMR proteins in a non-negligible percentage of CRCs (11.5%), where heterogeneous nuclear expression of MMR proteins was described in several different forms.
The size of circulating immune complexes (CICs) in rheumatoid arthritis (RA) could be an emerging criterion in disease diagnosis. This study analyzed size and electrokinetic potential of CICs from RA ...patients, healthy young adults, and RA patients age-matched controls aiming to establish their unique CIC features. Pooled CIC of 30 RA patients, 30 young adults, and 30 RA group's age-matched controls (middle-aged and oldеr healthy adults), and in vitro IgG aggregates from pooled sera of 300 healthy volunteers were tested using dynamic light scattering (DLS). Size distribution of CIC in healthy young adults exhibited high polydispersity. RA CIC patients and their age-matched control showed distinctly narrower size distributions compared with young adults. In these groups, particles clustered around two well-defined peaks. Particles of peak 1 were 36.1 ± 6.8 nm in RA age-matched control, and 30.8 ± 4.2 nm in RA patients. Particles of peak 2 of the RA age-matched control's CIC was 251.7 ± 41.2 nm, while RA CIC contained larger particles (359.9 ± 50.5 nm). The lower zeta potential of RA CIC, compared to control, indicated a disease-related decrease in colloidal stability. DLS identified RA-specific, but also age-specific distribution of CIC size and opened possibility of becoming a method for CIC size analysis in IC-mediated diseases.
Display omitted
•Circulating immune complexes (CICs) size in rheumatoid arthritis (RA) could be an emerging criterion in disease diagnosis.•The CICs size of RA patients' sera can be determined by dynamic light scattering (DLS).•DLS identified RA-specific, but also age-specific distribution of CICs size.•Zeta potential revealed an RA-related decrease in the colloidal stability of CICs.•DLS could be a method for CIC size analysis in IC-mediated diseases.
Dural metastases originating from prostate cancer are exceedingly uncommon and may clinically imitate a subdural hematoma. Additionally, head computed tomography scan findings can be mistaken for ...meningioma or subdural hematoma. We present a 75-year-old male patient with dural metastasis as a first presenting sign of prostate cancer, misdiagnosed as a bilateral subdural hematoma on initial non-contrast brain CT scan. Also, a review of literature is presented. We found 12 cases of dural metastasis of prostate cancer mimicking subdural hematoma described in the literature, and unlike in our case, prostate cancer was already diagnosed.
Slaughterhouse blood represents a valuable source of hemoglobin, which can be used in the production of heme-iron based supplements for the prevention/treatment of iron-deficiency anemia. In order to ...obtain a stable solid-state formulation, the effect of maltose addition (30 %) on the stability and storage of bovine and porcine hemoglobin in powders obtained by spray and freeze-drying (without maltose: Hb; with maltose: HbM) were investigated. Differential scanning calorimetry of spray- and freeze-dried powders indicated satisfying quality of the formulation prepared with maltose on dissolving back into solution. After two-year storage at room temperature (20?5?C) in solid forms, protected from moisture and light, rehydrated spray- and freeze-dried HbM were red, while Hb were brown. Dynamic light scattering showed the presence of native hemoglobin monomers in rehydrated spray- and freeze-dried HbM, but their agglomerates in Hb samples. UV?Vis spectrophotometry confirmed an absence of significant hemoglobin denaturation and methemoglobin formation in HbM freeze-dried powders. In spray-dried HbM, an increased level of methemoglobin was detected. The results confirmed the stabilizing effect of maltose, and suggested its use in the production of long-term stable solid-state formulations of hemoglobin, along with drying processes optimization.
nema
We have studied Ho-doped BiFeO3 nanopowders (Bi1−xHoxFeO3, x = 0–0.15), prepared via sol-gel method, in order to analyse the effect of substitution-driven structural transition on dielectric and ...ferroelectric properties of bismuth ferrite. X-ray diffraction and Raman study demonstrated that an increased Ho concentration (x ≥ 0.1) has induced gradual phase transition from rhombohedral to orthorhombic phase. The frequency dependent permittivity of Bi1−xHoxFeO3 nanopowders was analysed within a model which incorporates Debye-like dielectric response and dc and ac conductivity contributions based on universal dielectric response. It was shown that influence of leakage current and grain boundary/interface effects on dielectric and ferroelectric properties was substantially reduced in biphasic Bi1−xHoxFeO3 (x > 0.1) samples. The electrical performance of Bi0.85Ho0.15FeO3 sample, for which orthorhombic phase prevailed, was significantly improved and Bi0.85Ho0.15FeO3 has sustained strong applied electric fields (up to 100kV/cm) without breakdown. Under strong external fields, the polarization exhibited strong frequency dependence. The low-frequency remnant polarization and coercive field of Bi0.85Ho0.15FeO3 were significantly enhanced. It was proposed that defect dipolar polarization substantially contributed to the intrinsic polarization of Bi0.85Ho0.15FeO3 under strong electric fields at low frequencies.
Modified ultrafiltration has gained wide acceptance as a powerful tool against cardiopulmonary bypass morbidity in pediatric cardiac surgery. The aim of our study was to assess the importance of ...modified ultrafiltration within conditions of contemporary cardiopulmonary bypass characteristics.
Ninety⁻eight patients (overall cohort) weighing less than 12 kg undergoing surgical repair with cardiopulmonary bypass were prospectively enrolled in a randomized protocol to receive modified and conventional ultrafiltration (MUF group) or just conventional ultrafiltration (non-MUF group). A special attention was paid to forty-nine neonates and infants weighing less than 5 kg (lower weight (LW) cohort).
Post-filtration hematocrit was significantly higher in the MUF group for both cohorts (overall cohort
= 0.001; LW cohort
= 0.04), but not at other time points. During the postoperative course, patients in the MUF group received fewer packed red blood cells, (overall cohort
= 0.01; LW cohort
= 0.07), but required more fresh frozen plasma (overall cohort
= 0.04; LW cohort
= 0.05). There was no difference between groups in hemodynamic state, chest tube output, duration of mechanical ventilation, respiratory parameters, duration of intensive care unit, and hospitalization stay.
If conventional ultrafiltration provides adequate hemoconcentration modified ultrafiltration does not provide additional positive benefits except for reduction in blood cell transfusion, This, however, comes at the cost of needing more fresh frozen plasma. Of particular importance is that this also applies to infants with weight bellow 5 kg where modified ultrafiltration was supposed to have the greatest positive impact.
Purpose
Data on the seroprevalence of hepatitis E virus (HEV) in heamodialysis (HD) patients are conflicting, ranging from 0 to 44%. The aim of this study was to determine the HEV seroprevalence and ...risk factors among HD patients in Croatia.
Methods
A total of 394 HD patients from six medical facilities in five Croatian cities (three sites in the continental and three sites in the coastal region) were tested for HEV IgM/IgG antibodies using an enzyme-linked immunosorbent assay. Additionally, all samples were tested for HEV RNA by RT-PCR. Sociodemographic data and risk factors were collected using a questionnaire.
Results
HEV IgG antibodies were detected in 110 (27.9%) patients. The seroprevalence varied significantly between dialysis centres, ranging from 5.2 to 43.4% (
p
= 0.001). HEV IgM antibodies were found in 0.04% of IgG positive patients. All patients tested negative for HEV RNA. Factors associated with HEV IgG seropositivity were age > 60 years (OR 8.17; 95% CI 1.08–62.14), living in the continental parts of the country (OR 2.58; 95% CI 1.55–4.30), and transfusion of blood products (OR 1.66; 95% CI 1.01–2.73). After adjusting for age and gender, patients from continental regions had higher odds of HEV seropositivity compared to patients from coastal regions (OR 2.88; 95% CI 1.71–4.85) and those who had RBC transfusions (OR 1.70, 95% CI 1.02–2.69) compared to those who did not.
Conclusion
The study showed a high HEV seropositivity among HD patients in Croatia, with significant variations between geographical regions. Continental area of residence and RBC transfusion were the most significant risk factors for HEV seropositivity. Due to the high seroprevalence, routine HEV screening among HD patients, especially in transplant candidates should be considered.
PDF
