Designing a tunable acoustic resonator based on defect modes, stimulated by selectively biased PZT rods in a 2D phononic crystal.

Reconfigurable phononic crystals (PnCs) and related devices are highly attractive because of their flexibility for different applications. We present the design procedure for a tunable acoustic resonator based on a 2D PnC, consisting of a periodic array of piezoelectric rods of radii 175 µm as inclusions arranged in air background. A single point defect devised by a rod of radius 161 µm, replacing one of the inclusions, plays the role of the acoustic resonator, leading to a defect frequency in the phononic band gap (fd ≈ 432 kHz). Applying a ∼1% strain to the defect rod, via an external voltage, tunes the defect resonant frequency within the phononic band gap. It is shown that the maximum tunability and the frequency shift depends on the defect size, and is achieved about Δfd = 440 Hz for the defect with the expense of descending quality factor. Considering the pattern of the localized pressure field, we introduce a multi-defect structure with five symmetric defect rods, corresponding to the maxima of field distribution. It is shown that maximum frequency shift of the dominant defect frequency is achieved about Δfd = 1.14 kHz for defect radius of 161 µm, when all five defect rods are strained. The proposed tunable filter based on multi-defect structure results in an enhancement of about 2.6 times in the maximum frequency shift, in comparison with the single defect structure, and introduces a promising approach for realizing tunable acoustic devices.

Selective and metal-free epoxidation of terminal alkenes by heterogeneous polydioxirane in mild conditions.

Polydioxirane (PDOX) was prepared by the treatment of polysalicylaldehyde with Oxone and was found as a selective, highly efficient and heterogeneous reagent for epoxidation of alkenes which can be successfully isolated. This work also introduced a simpler, safer and milder way for epoxidation of alkenes with dioxirane groups than before. PDOX can be simply recovered from the reaction mixture by plain filtration and reused for eight runs without significant reactivity loss.

Extraction of Citrus paradisi Volatile Components by Headspace Single-Drop Microextraction and Statistical Modeling.

In present study, headspace single-drop microextraction (HS-SDME) was applied for the extraction and preconcentration of the volatile components of the plant sample into a microdrop surface. The extraction occurred by suspending a microliter drop of the solvent from the tip of a microsyringe to the headspace of a ripe fruit sample (grapefruit Citrus paradisi) in a sealed vial for a preset extraction time. Then the microdrop was retracted back into the microsyringe and injected directly into a gas chromatography injection port. The chemical composition of the SDME extracts was confirmed according to their mass spectra, and quantitative analysis was performed by gas chromatography-flame ionization detector (GC-FID). Response surface methodology along with Box-Behnken design was applied to optimize the extraction condition of four components, d-limonene, ß-myrcene, α-pinene and ß-pinene, from the peel of grapefruit. Parameters considered for SDME include the kind of the extracting solvent, size of drop, extraction temperature and extraction time. The optimized condition was microdrop volume of 1 µL, extraction time of 2 min and sample temperature of 50°C.

Co-infection of Malaria and Crimean-Congo Hemorrhagic Fever.

Southeast of Iran is an endemic area for Malaria and Crimean-Congo hemorrhagic fever (CCHF). In 1999, we faced with an outbreak of CCHF in Sistan and Baluchistan Province, in the border of Pakistan and Afghanistan. The most cases of Malaria in Iran are also reported from this area. This article presents a 17-year- old woman who admitted to our hospital because of acute fever, headache, epistaxis, hemorrhagic lesions on the skin and vaginal bleeding. Finally, she was recognized as a case that was co -infected with CCHF and malaria.

Can Doppler ultrasonographic indices of the renal artery predict the presence of supernumerary renal arteries?

BACKGROUND: Variations of the renal arteries, including the presence of supernumerary renal arteries, are important to be identified prior to renal transplant. Angiography has been the gold standard test for the pretransplant evaluation of the renal vasculature. However, this modality is expensive and invasive. The aim of this study was to assess whether Doppler ultrasonographic (DU) indices of the renal artery could predict the presence of supernumerary renal arteries. METHODS AND MATERIALS: Retrospectively, we analyzed multidetector computed tomography angiography (presence or absence of the supernumerary renal artery), DU (peak systolic velocity, resistive index, pulsatility index, end-diastolic velocity, and acceleration time) findings of 30 healthy potential renal transplant donors. Recipient operator characteristic (ROC) curves were used to examine the predictive values of the available DU indices for supernumerary renal arteries. RESULTS: The mean age of donors was 28.4 +/- 4.1 years. Of 60 kidneys evaluated, a supernumerary renal artery was found in 10%. The ROC curve analysis revealed an area under the curve of noninformative (below 0.5) for all DU parameters, indicating that none of the studied parameters could predict the presence of a supernumerary renal artery. CONCLUSIONS: Although the smaller diameter of the main renal artery has previously been found to predict the presence of supernumerary renal arteries, the present study revealed that DU indices of the renal artery may not indicate the presence of supernumerary renal arteries.

Ultrasound findings in biliary atresia: the role of triangular cord sign.

In this prospective study, 49 infants with prolonged jaundice, were studied between January 2005 to April 2007 in Tabriz Children's Hospital. All of these infants were evaluated with ultrasonography and isotopscan and finally biopsy was done in all of them under guide of sonography. In their sonographic evaluation, absence or presence of gall bladder, its size and also its evacuation after feeding was checked and beside this triangular cord sign was controlled. The PPV and specificity of triangular cord sign in diagnosis of extrahepatic biliary atresia (EHBA) was 100% but its NPV was only 78.5%. The overall accuracy, PPV, NPV, specificity and sensitivity ofultrasonographic findings in diagnosis of EHBA was about 94, 92, 94, 97 and 86%. Ultrasonography is a reliable screening method in early diagnosis of EHBA and triangular cord sign increases its accuracy especially its specificity.

Screening for renal artery stenosis in patients with aorticoiliac occlusive disease.

BACKGROUND: The prevalence of atherosclerotic renal artery disease has increased with improved life expectancy. Because renal artery stenosis is a potentially correctable cause of hypertension and ischemic nephropathy, early identification of this entity may lead to proper hypertension control and improved renal function and survival. The aim of this study was to determine the prevalence and patterns of subclinical renal artery stenosis in patients with aorticoiliac atherosclerosis. PATIENTS AND METHODS: The abdominal angiographies of 44 patients with high-grade aorticoiliac occlusive disease (> 70% stenosis) were reviewed for evidence of renal artery stenosis. This was compared to a group of 20 patients with mild-to-moderate aorticoiliac disease (< 70% stenosis). These patients had no history of renal artery disease or renal failure. RESULTS: In patients with high-grade aorticoiliac occlusive disease, renal artery stenosis was found in 25 patients (56.8%); 13 with unilateral (29.5%) and 12 (27.3%) with bilateral involvement. A hemodynamically significant stenosis (> 50%) was found in 11 patients (25%), one of whom had bilateral stenosis (2.3%). High-grade renal artery stenosis (> 70%) or complete arterial occlusion was noted on seven sides (7.9%). The most common sites of stenosis were the origin and first centimeter of the renal artery. In patients with mild-to-moderate aorticoiliac disease, renal artery stenosis was found in two patients (10%). CONCLUSIONS: The present study revealed that subclinical renal artery disease may be present in more than half of the patients with high-grade aorticoiliac atherosclerosis highlighting the need for proper risk stratifications and screening programs. Based on our results, we suggest that examination of the renal arteries in these patients may be necessary in order to delay or prevent complications. Additionally, such information may have important therapeutic implications in planning reconstructive vascular surgeries or percutaneous angioplasties.

The diagnostic value of the resistivity index of the common carotid arteries in severe internal carotid artery stenosis.

Duplex ultrasound is currently used both for screening and for preoperative assessment of the carotid arteries and has completely replaced carotid angiography for the latter purpose in many institutions. The study aimed to identify resistivity index abnormalities in the common carotid arteries in patients with occluded or severely stenosed internal carotid arteries. Sixteen patients with severe internal carotid artery stenosis or occlusion over a twelve-month period were studied by duplex ultrasonography. The resistivity index in the common carotid artery was 0.85 +/- 0.03 on the stenotic side compared to 0.74 +/- 0.04 on the opposite side (p < 0.05). There was no side difference regarding flow velocity. In patients with occluded or severely stenosed internal carotid arteries compensatory vasodilation occurs in cerebral vessels on the same side, and this is also significant, resulting in a decrease in the resistivity index in the common carotid artery of the opposite side.

Screening for thoracoabdominal aortic aneurysms in patients with aortoiliac atherosclerosis: a preliminary study.

Thoracoabdominal aortic aneurysms (TAAs) usually present with rupture and carry a high morbidity and mortality rate. Early detection of TAAs with screening methods and elective surgical repair could potentially diminish these complications. The present study was aimed at screening for TAA in patients with angiography-proven aortoiliac atherosclerosis (n=43). A group of patients without aortoiliac atherosclerosis was used as controls (n=15). Age, sex and aortic diameter at the level of the T12 vertebra were recorded. The subjects were divided into two age categories, the first made up of those aged less than 65 years and the second those aged 65 years or more. A T12 aortic diameter greater than 35 mm was used to indicate TAA. Statistical analyses were performed by independent t-test and general linear model with age category, sex and atherosclerosis as factors. The mean T12 aortic diameters were greater in patients with atherosclerosis than in the control group (25.2+/-5.0 vs. 22.9+/-2.4 mm; p=0.034). Two out of 43 patients (4.7%) with aortoiliac atherosclerosis had TAA, while no one in the control group had TAA. A general linear model showed that the interaction of age category and sex significantly affected the T12 aortic diameter [F (1.49)=4.044, p=0.050]. Post hoc (LSD) tests revealed that male patients aged over 65 had greater T12 aortic diameters than other patients. We conclude that patients with aortoiliac atherosclerosis may be at greater risk for developing TAA. Ageing and male sex may also be associated with thoracoabdominal aortic enlargement.

Aortic bifurcation angle as an independent risk factor for aortoiliac occlusive disease.

Recently, there has been interest in potential geometric risk factors that might result in or exaggerate atherosclerosis. The aortic bifurcation is a complex anatomical area dividing the high pressure blood of the descending abdominal aorta into the lower limbs and pelvis. The distribution of the bifurcation angle and any asymmetry, its relation with age and its possible contribution to the risk of aortoiliac atherosclerosis are presented here. Statistical analysis was performed by SPSS version 11.0 using, Fisher;s exact test, the Pearson and Spearman correlation tests and logistic regression analysis. The p value was set at 0.05. No correlations were found between age, bifurcation angle and angle asymmetry in the Pearson test (p > 0.05). Logistic regression analysis revealed that the bifurcation angle, but not its asymmetry, gender or age, was a significant and independent risk factor for aortoiliac atherosclerosis (model r(2) = 0.662, p = 0.027). With additional study these results may have implications regarding risk factors for aortoiliac atherosclerosis. To our knowledge, this study is the first of its kind to indicate the potential of such an important geometric risk factor for atherosclerosis at the aortic bifurcation.

Does a third head of the rectus femoris muscle exist?

Current anatomical texts describe only two tendinous origins of the rectus femoris muscle. The authors identified one older reference in which a third head of the rectus femoris muscle was briefly described. In order to confirm the existence of this head, 48 adult cadavers (96 sides) underwent detailed dissection of the proximal attachments of the rectus femoris muscle. Of these sides 83% were found to harbour a recognised third head of the rectus femoris muscle. This additional head was found to attach deeply to the iliofemoral ligament and superficially with the tendon of the gluteus minimus muscle as it attached into the femur. This tendon attached to the anterior aspect of the greater trochanter in an inferolateral direction compared to the straight head. The mean length and width of the third head was 2 cm and 4 cm, respectively. The mean thickness was found to be 3 mm. Most commonly this third head was bilaterally absent or bilaterally present. However, 4.2% were found only on left sides and 5.2% were found only on right sides. The angle created between the reflected and third heads was approximately 60 degrees. Two sides (both left sides with one female and one male specimen) were found to have third heads that were bilaminar. These bilaminar third heads had a distinct layer attaching to the underlying iliofemoral ligament and a superficial layer blending with the gluteus minimus tendon to insert onto the greater trochanter. Although the function of such an attachment is speculative, the clinician may wish to consider this structure in the interpretation of imaging or in surgical procedures in this region, as in our study it was present on the majority of sides.

The most common anatomical sites of arterial injury in the extremities: a review of 75 angiographically-proven cases.

The incidence of vascular injury has increased worldwide. In an attempt to quantitate the specific arteries most commonly involved in the extremities, we reviewed 75 patients with extremity trauma who were evaluated with angiography (DSA, digital subtraction angiography). The majority of these injuries were related to motor vehicle accidents (93.3%). The mean age of these patients was 28.16 +/- 11.14 years, 94.7% of these patients being male. The ratio of upper to lower extremity arterial trauma was 12 to 86. A total of 99 arterial injuries were detected angiographically. Simultaneous injuries to two and three extremity arteries were identified in 13.3% and 9.3% of patients respectively. The most common arteries injured were the anterior tibial, femoral, peroneal, and popliteal arteries. Associated fractures were present in 86.7% of patients. These data may prove useful to the clinician who evaluates post-traumatic injuries of the extremities.

Bilateral accessory middle cerebral arteries associated with an aneurysm of the anterior circulation.

An accessory middle cerebral artery is one variation of the intracranial vasculature that may be a source of misinterpretation by clinicians dealing with cerebrovascular diseases. We report a case of an elderly female found to have bilateral accessory middle cerebral arteries, who presented with the rupture of an aneurysm of the anterior part of the circle of Willis. Accessory middle cerebral arteries are rare anatomical findings and the bilateral occurrence is exceedingly rare. We believe this to be the first report of bilateral accessory middle cerebral arteries associated with an aneurysm of the anterior cerebral-anterior communicating arteries. The anatomical and clinical relevance of this variation is described.