AIN-Based Packaging for SiC High-Temperature Electronics

Packaging made primarily of aluminum nitride has been developed to enclose silicon carbide-based integrated circuits (ICs), including circuits containing SiC-based power diodes, that are capable of operation under conditions more severe than can be withstood by silicon-based integrated circuits. A major objective of this development was to enable packaged SiC electronic circuits to operate continuously at temperatures up to 500 C. AlN-packaged SiC electronic circuits have commercial potential for incorporation into high-power electronic equipment and into sensors that must withstand high temperatures and/or high pressures in diverse applications that include exploration in outer space, well logging, and monitoring of nuclear power systems. This packaging embodies concepts drawn from flip-chip packaging of silicon-based integrated circuits. One or more SiC-based circuit chips are mounted on an aluminum nitride package substrate or sandwiched between two such substrates. Intimate electrical connections between metal conductors on the chip(s) and the metal conductors on external circuits are made by direct bonding to interconnections on the package substrate(s) and/or by use of holes through the package substrate(s). This approach eliminates the need for wire bonds, which have been the most vulnerable links in conventional electronic circuitry in hostile environments. Moreover, the elimination of wire bonds makes it possible to pack chips more densely than was previously possible

The problem of hypoxic nephropathy diagnosis in premature infants and its solutions

The study included 120 premature infants suffering from perinatal hypoxia, which have been divided into two groups by birth weight: group 1 – less than 1500 g, group 2 – more than 1500 g. Severity of renal disease was defined by creatinine and cystatin C levels in serum, interleukin-18 (IL-18) and lipocalin (NGAL) levels in urine on the 3rd-5th day of life, parameters of renal blood flow. The study found a significant increase (3 times) of serum creatinine in children of the test groups (p < 0.05) compared to the controls. The serum levels of cystatin C on the 3rd-5th day of life were 2.6 ± 0.21 ng/ ml (group 1) and 1.9 ± 0.12 ng/ml (group 2) that is significantly higher than in the controls (p < 0.01). The content of NGAL in newborns suffering from hypoxic nephropathy was 2.5-3 times higher than in the controls (p < 0.01). IL-18 levels were significantly higher too (p < 0.01). Renal blood flow investigation showed a significant decrease of systolic flow velocity in the trunk of the renal arteries and of pulsatility index (PI) among newborns affected. The study established clinical and laboratory features of hypoxic nephropathy in premature infants – edema and proteinuria of various severity, early significant increase in serum cystatin C, as well as lipocalin and IL-18 in urine, a significant reduction of the maximal systolic flow velocity in the trunk of the renal arteries and PI (p < 0.05) - that were more evident among the children with weight < 1500 g

Temperature Induced Voltage Offset Drifts in Silicon Carbide Pressure Sensors

We report the reduction of transient drifts in the zero pressure offset voltage in silicon carbide (SiC) pressure sensors when operating at 600 C. The previously observed maximum drift of +/- 10 mV of the reference offset voltage at 600 C was reduced to within +/- 5 mV. The offset voltage drifts and bridge resistance changes over time at test temperature are explained in terms of the microstructure and phase changes occurring within the contact metallization, as analyzed by Auger electron spectroscopy and field emission scanning electron microscopy. The results have helped to identify the upper temperature reliable operational limit of this particular metallization scheme to be 605 C

The Effect of Hemorrhage Volume on Mortality in Spontaneous Intracerebral Hemorrhages

INTRODUCTION: Spontaneous intracerebral hemorrhage is associated with severe morbidity and mortality. In this study, it was aimed to investigate the effect of hemorrhage volume and other known prognostic factors on mortality in spontaneous intracerebral hemorrhages. METHODS: The study was performed retrospectively in patients diagnosed with spontaneous intracerebral hemorrhage at a state hospital emergency department between 01/01/2014- 31/12/2019. Ethical approval was obtained from the Local Clinical Research Ethics Committee for the study. Patients' age, gender, systemic disease, antiaggregant or anticoagulant medication use, systolic blood pressure (SBP) and Glasgow Coma Scale (GCS), INR, hemorrhage volume, ventricular extension of hemorrhage and location determined by computed tomography (CT), ICH (Intracerebral Hemorrhage) Score, 30-day mortality data were retrospectively assessed for the study. RESULTS: A total of 55 patients, 26 males (47.27%), 29 females (52.73%) were included in the study. The mean age was detected as 70 +- 13. The 30-day mortality rate was 49.09%. Mortality was significantly higher in patients with ventricular extension of hemorrhage (p &lt;0.001). When subgroup analysis was done, in the group with mortality in supratentorial hemorrhages, the volume of hemorrhage was significantly higher (p &lt;0.001). A moderate to high degree of negative correlation was found between GCS and hemorrhage volume (p &lt;0.001; rho = -0.599). When multivariate analysis of factors predicting mortality was performed, only GCS had an effect on mortality. DISCUSSION AND CONCLUSION: Hemorrhage volume is associated with increased mortality in spontaneous intracerebral supratentorial hemorrhages. Lower GCS on admission was associated with mortality in our retrospective cohort study

Demonstration of SiC Pressure Sensors at 750 C

We report the first demonstration of MEMS-based 4H-SiC piezoresistive pressure sensors tested at 750 C and in the process confirmed the existence of strain sensitivity recovery with increasing temperature above 400 C, eventually achieving near or up to 100% of the room temperature values at 750 C. This strain sensitivity recovery phenomenon in 4H-SiC is uncharacteristic of the well-known monotonic decrease in strain sensitivity with increasing temperature in silicon piezoresistors. For the three sensors tested, the room temperature full-scale output (FSO) at 200 psig ranged between 29 and 36 mV. Although the FSO at 400 C dropped by about 60%, full recovery was achieved at 750 C. This result will allow the operation of SiC pressure sensors at higher temperatures, thereby permitting deeper insertion into the engine combustion chamber to improve the accurate quantification of combustor dynamics

Characterization of Silicon Carbide Pressure Sensors at 800 C

We have performed the initial characterization of single crystal 4H silicon carbide (4H-SiC) pressure sensors to determine the operational reliability over time at 800 C. Important parameters such as the zero pressure offset, bridge resistance, and pressure sensitivity as they are affected by temperature were extracted. These parameters showed relative stability within the prescribed operational envelop of the sensor at 800 C. Of significance is the increase in pressure sensitivity with increasing temperature beyond 400 C, to the extent that the sensitivity at 800 C was higher than the room temperature value. The implication of this result is that the sensor can be inserted further into the high temperature environment, thereby capturing the wider bandwidth of the pressure transients than currently possible

High Temperature Dynamic Pressure Measurements Using Silicon Carbide Pressure Sensors

Un-cooled, MEMS-based silicon carbide (SiC) static pressure sensors were used for the first time to measure pressure perturbations at temperatures as high as 600 C during laboratory characterization, and subsequently evaluated in a combustor rig operated under various engine conditions to extract the frequencies that are associated with thermoacoustic instabilities. One SiC sensor was placed directly in the flow stream of the combustor rig while a benchmark commercial water-cooled piezoceramic dynamic pressure transducer was co-located axially but kept some distance away from the hot flow stream. In the combustor rig test, the SiC sensor detected thermoacoustic instabilities across a range of engine operating conditions, amplitude magnitude as low as 0.5 psi at 585 C, in good agreement with the benchmark piezoceramic sensor. The SiC sensor experienced low signal to noise ratio at higher temperature, primarily due to the fact that it was a static sensor with low sensitivity

Spinal myoclonus following a peripheral nerve injury: a case report

Spinal myoclonus is a rare disorder characterized by myoclonic movements in muscles that originate from several segments of the spinal cord and usually associated with laminectomy, spinal cord injury, post-operative, lumbosacral radiculopathy, spinal extradural block, myelopathy due to demyelination, cervical spondylosis and many other diseases. On rare occasions, it can originate from the peripheral nerve lesions and be mistaken for peripheral myoclonus. Careful history taking and electrophysiological evaluation is important in differential diagnosis

ДOCBIДЛIКУBAHHЯ BУЛЬBOBAГIHITIB ПОЄДНАНИХ З ДИСПЛАЗІЯМИ ШИЙКИ МАТКИ.

To study the ciinicai and iaboratory efficacy and safety of vaginai use of the Lomeksin for the treatment of vuivovaginitis caused by Candida and microbiaiassociations in conjunction with squamous cervicai dyspiasia there were examined and treated 5O patients aged 18 to З? years, mean age was 2З,9±5,4 years. Vuivoginitis, caused by fungi, vegetating in the form of yeast, budding fungi and in the form of myceiium, diagnosed in 1З.8 % microscopy of vaginai smears . However, oniy in 5O.O %of patients we diagnosed opportunistic fiora in the form of Gram-positive coccus, and the compiete absence of Doderiein baciiiusat54.O % and their faiiure in44.O % of patients. In our opinion, suchmicrobiocenosis of vagina preciudes therapeutic purposes preparations containing antibiotics. Ciinicai and iaboratory efficacy of the Lomeksin for vuivoginitis treatment caused by yeast fungi in vegetative forms, in conjunction with opportunistic coccai fiora was 94.O %. High efficacy, toierabiiity, ease of use, avaiiabiiity of dosage forms for simuitaneous treatment of sexuai partners and the absence of side effects can be recommended for wide use in ciinicai practice.С целью изучения клинической и лабораторной эффективности и безопасности вагинального применения препарата Ломексин для лечения вульвовагинитов, обусловленных кандидами и микробными ассоциациями в сочетании с плоскоклеточной дисплазией шейки матки обследовано и пролечено 5O больных в возрасте от 18 до З? лет, средний возраст составил 2З,9±5,4 лет. Byльвoгиниты, обусловленные грибами, вегетирующими в форме дрожжей , грибами почкующимися и в форме мицелия, диагностируются в 1З,8 % микроскопий влагалищных мазков. При этом лишьу 5O,O % больных диагностируется условно-патогенная флора ввиде грамположительных кокков, а полное отсутствие палочек Додерлейна у 54,O % и их недостаточность у 44,O % больных. По нашему мнению, подобный микробиоценоз влагалища исключает возможность применения с лечебной целью препаратов, содержащих антибиотики. Клиническая и лабораторная эффективность применения препарата Ломексин для лечениявульвогинитив, обусловленных дрожжевыми грибами в вегетирующих формах, в комплексе с условно-патогенной кокковой флорой составляла 94,O %. Bыcoкaя эффективность препарата, хорошая переносимость, удобство применения, наличие лекарственных форм для одновременного лечения половых партнеров и отсутствие побочных эффектов позволяют рекомендовать его для широкого использования в клинической практике. З метою вивчення клінічної та лабораторної ефективності і безпечності вагінального застосування препарату Ломексин для лікування вульвовагінітів, обумовлених кандидами і мікробними асоціаціями в сполученні з плоскоклітинними дісплазіями шийки матки обстежено іпроліковано 5O хворих віком від 18 до З? років, середній вік склав 2З,9±5,4 років. Byльвoгiнiти, які обумовлені грибами, що вегетуютьу формі дріжджів, грибами, що брунькуються, й у формі міцелію, діагностуються у 1З,8 % мікроскопій вагінальних мазків. При цьому тільки у 5O,O % хворих діагностується умовно-патогенна флора у вигляді грампозитивних коків, а повна відсутність паличок Додерлейна у 54,O % і їхня недостатність у 44,O % хворих. На нашу думку, подібний мікробіоценоз піхви виключає можливість застосування з лікувальною метою препаратів, які містять антибіотики. Клінічна і лабораторна ефективність застосування препарату Ломексин для лікування вульвогінітів, обумовлених дріжджовими грибами у формах, що вегетують, в комплексі з умовно-патогенною коковою флорою становила 94,O %. Bиcoкa ефективність препарату, добра переносність,зручність застосування, наявність лікарських форм для одночасного лікування статевих партнерів та відсутність побічних ефектів дозволяють рекомендувати його для широкого використання у клінічній практиці