Water content measurement in black spruce and aspen sapwood with benchtop and portable magnetic resonance devices

Abstract

In this study, water content in black spruce (Picea mariana Mill.) and aspen (Populus tremuloides Michx.) sapwood samples was investigated with time-domain magnetic resonance (MR). Time-domain MR measurements easily distinguish water in different environments in wood according to the spin-spin relaxation time and provide quantitative information on water content. The MR techniques employed can distinguish and quantify the individual signal components. Both black spruce and aspen have two signal components at moisture contents above the fiber saturation point. These two signal components correspond to motionally restricted water, often referred to as bound water, and unrestricted, or free water. Bound water content is constant above 40% moisture content. No signal from free water was detected at or below 20% moisture content in either species. We also demonstrate the use of a recently developed portable unilateral magnet that can be employed as a powerful tool in the study and measurement of water content in wood.     

低模数水玻璃对橡胶轻骨料混凝土力学性能的影响

为了了解不同掺量水玻璃对RLC(橡胶轻骨料混凝土)力学性能的影响,在RLC中加入水玻璃,并用20%粉煤灰代替水泥,制作水玻璃掺量分别为0,2%,4%,6%,8%的混凝土试块.通过核磁共振试验研究其微观孔隙变化及强度形成机理;进行对数函数曲线预测和BP神经网络强度预测,判断其可靠性并对比优劣.结果表明:水玻璃的掺入使RLC抗压强度呈现先增大后减小的趋势,其水玻璃最优掺量出现在2%;适量水玻璃的加入可提高80 目RLC力学性能,使其与最优组(20 目RLC组)28 d力学性能基本相同;水玻璃加入后混凝土孔隙度呈现出先减小后增大趋势,说明适量水玻璃的掺入可优化混凝土孔隙结构,提高混凝土强度;建立曲线拟合和BP-神经网络预测模型,2种预测模型都可用于混凝土龄期强度预测,但BP-神经网络预测模型的稳定性、可靠性及参数的全面性要优于曲线拟合模型.     

Use of Contrast‐Enhanced Fluid‐Attenuated Inversion Recovery Sequence to Detect Brain Lesions in Dogs and Cats

Background

The diagnostic value of a contrast‐enhanced T2‐weighted FLAIR sequence (ceFLAIR) in brain imaging is unclear.

Hypothesis/Objectives

That the number of brain lesions detected with ceFLAIR would be no greater than the sum of lesions detected with nFLAIR and ceT1W sequence.

Animals

One hundred and twenty‐nine animals (108 dogs and 21 cats) undergoing magnetic resonance imaging (MRI) of the head between July 2010 and October 2011 were included in the study.

Methods

A transverse ceFLAIR was added to a standard brain MRI protocol. Presence and number of lesions were determined based on all available MRI sequences by 3 examiners in consensus and lesion visibility was evaluated for nFLAIR, ceFLAIR, and ceT1W sequences.

Results

Eighty‐three lesions (58 intra‐axial and 25 extra‐axial) were identified in 51 patients. Five lesions were detected with nFLAIR alone, 2 with ceT1W alone, and 1 with ceFLAIR alone. Significantly higher numbers of lesions were detected using ceFLAIR than nFLAIR (76 versus 67 lesions; P = 0.04), in particular for lesions also detected with ceT1W images (53 versus 40; P =.01). There was no significant difference between the number of lesions detected with combined nFLAIR and ceT1W sequences compared to those detected with ceFLAIR (82 versus 76; P =.25).

Conclusion and Clinical Importance

Use of ceFLAIR as a complementary sequence to nFLAIR and ceT1W sequences did not improve the detection of brain lesions and cannot be recommended as part of a routine brain MRI protocol in dogs and cats with suspected brain lesions.     

Chiari‐Like Malformation and Syringomyelia in American Brussels Griffon Dogs

Background

Although Chiari‐like malformation (CM) and syringomyelia (SM) have been described in many small breed dogs, the prevalence and clinical manifestations of this complex have not been documented in a large cohort of American Brussels Griffon (ABG) dogs.

Objectives

To characterize the clinical and magnetic resonance imaging (MRI) features of CM and SM in the ABG breed.

Animals

Eighty‐four American Kennel Club registered ABG dogs were recruited.

Methods

Prospective study. Complete histories and neurologic examinations were obtained before MRI. Images were blindly reviewed and calculations were made by using OsiriX. All analyses were performed by Student''s t‐test, Spearman''s correlation, ANOVA, and chi‐square test where appropriate.

Results

Chiari‐like malformation and SM were present in 65% and 52% of dogs, respectively. Twenty‐eight percent of dogs had neurologic deficits and 20% had neck pain. Mean central canal (CC) transverse height was 2.5 mm with a mean length of 3.6 cervical vertebrae. Neurologic deficits were significantly associated with a larger syrinx (P = .04, P = .08) and syrinx size increased with age (P = .027). SM was associated with a smaller craniocervical junction (CCJ) height (P = .04) and larger ventricles (P = .0001; P < .001).

Conclusions and Clinical Importance

Syringomyelia and CM are prevalent in American Brussels Griffon dogs. Syrinx size is associated with neurologic deficits, CM, larger ventricles, a smaller craniocervical junction height, neurologic deficits, and cerebellar herniation. Fifty‐two percent of dogs with a SM were clinically normal.     

Congenital Peripheral Vestibular Syndrome in a Domestic Ferret (Mustela putorius furo)

A 3-month-old intact female ferret (Mustela putorius furo) was presented with a 2-month history of ataxia. On physical examination, the ferret had difficulty standing upright. During the neurologic examination, the patient had a left head tilt and positional strabismus, circled to the left, and was ataxic. Results of the complete blood count were consistent with a mild normocytic normochromic anemia. Initial treatment was supportive. Magnetic resonance imaging was performed and revealed an asymmetry of the inner ears. A brainstem auditory evoked response test was also performed. History, clinical signs, and diagnostic test results indicated that the ferret was suffering from congenital peripheral vestibular syndrome and left-sided deafness. Congenital disease should be considered in the differential diagnosis of young ferrets with peripheral vestibular syndrome. Supportive care and physiotherapy can improve balance and motor function, leading to an acceptable quality of life.     

Diagnostic imaging and pacemaker implantation in a domestic goat with persistent left cranial vena cava

Difficulty was encountered with the insertion of a right atrial pacing lead via the left jugular vein during lead and pacemaker implantation in a clinically normal goat as part of an ongoing rapid atrial pacing – induced atrial fibrillation research project. Fluoroscopic visualization of an abnormal lead advancement path prompted angiographic assessment which revealed a persistent left cranial vena cava (PLCVC) and prominent coronary sinus communicating with the right atrium. Angiography facilitated successful advancement and securing of the pacing lead into the right side of the interatrial septum. Cardiac magnetic resonance imaging/magnetic resonance angiography (MRI/MRA) allowed further characterization of this rare venous anomaly. Even though PLCVC has been reported once in a goat, to the authors' knowledge this is the first report to include MRI/MRA characterization of PLCVC and prominent coronary sinus with successful cardiac pacemaker implantation using the PLCVC.