Use Of Wafers Research Articles

170. The Nottingham Waferless Orthognathic Surgical Experience using In-House Reconstructive Scientists

Surgical planning of orthognathic cases has always followed the traditional planning route of models, lateral cephalogram, use of wafers and intra-operative fixation to predefined surgical wafers. In our unit we have modified this technique over the last five years and created a technique which is essentially waferless surgery with the aid of our reconstructive scientists who are based on site and provide us with surgical stents and pre-bent plates.

Closing the gap between n‐ and p‐type silicon heterojunction solar cells: 24.47% efficiency on lightly doped Ga wafers

AbstractSilicon heterojunction (SHJ) solar cells can be formed using n‐type or p‐type silicon wafers. To foster the increasing industrial interest of SHJ, cheaper p‐type wafers with a good availability might be preferred, but until today, they yield lower cell efficiency compared with n‐type and show instabilities in the particular case of boron doping. This work shows that the production flow of high performance rear‐junction bifacial n‐type cells can be applied to front‐junction p‐type cells without process alterations and with a loss of efficiency as low as −0.3%abs provided that the wafer bulk lifetime is high enough. For this, we propose the use of wafers with gallium doping on which we obtained on a semi‐industrial pilot line SHJ p‐type cells mostly stable under moderated heat and light and with an efficiency closed to n‐type references. The best p‐type cell was externally certified at 24.47% total area.

MiRNA-181d Expression Correlates in Tumor versus Plasma of Glioblastoma Patients—the Base of a Preoperative Stratification Tool for Local Carmustine Wafer Use

Patients with a low micro-RNA-181d (miRNA-181d) level in glioblastoma tissue benefit most of carmustine wafer use. The study compares preoperative miRNA-181d plasma and tumor expression. This may form the base to decide, from a preoperative blood test, if carmustine wafer implantation is recommendable. A total of 60 patients suffering from glioblastoma treated between 2018 and 2020 were enrolled prospectively. Preoperatively, blood was drawn and the plasma was isolated. Tumor specimens were collected. Blood samples from 30 healthy individuals served as a reference. MiRNA-181d expression in plasma and tumor were acquired as fold change, using quantitative reverse transcription-polymerase chain reaction. Results were correlated with relevant demographic, clinical, and histopathologic aspects of the cohort. Further factors like tumor volume as well as blood panel results were considered. The Cancer Genome Atlas analysis was performed to investigate specific miRNA-181d-protein interactions to elude how miRNA-181 impact therapy response to carmustine. Patients with glioblastoma showed a significant overexpression of miRNA-181d compared with healthy individuals (P= 0.029). There was a significant correlation between miRNA-181d expression in tumor tissue and plasma (P= 0.001, R= 0.51). The sensitivity of low miRNA-181d expression in plasma predicting low miRNA-181d tumor expression was 76.6%. Tumor volume, preoperative medication, and items of blood panel analysis did not influence the prognostic value of plasma miRNA-181d expression. The Cancer Genome Atlas analysis revealed 8 potential protein targets to be regulated by miRNA-181d. miRNA-181d seems to be a potential molecular marker that can reliably be detected in blood samples of patients with glioblastoma. It should therefore prospectively be evaluated as a potential preoperative prognostic marker regarding carmustine wafer implantation.

Processing Technology of Feed Wafer to Increase Feed Production and Efficiency

Feed is one of the important factor that affect livestock productivity, so the availability of good quality feed is a requirement for livestock development in an area. In the tropical area, providing forage as a crucial feed for ruminants was hampered by fluctuating seasons. Likewise, the availability of agricultural waste as an alternative source of feed material experiences the same constraints, easily damaged, and bulky (voluminous). Therefore, feed processing technology is needed so that it is become durable, easily stored, and easily provided for livestock. One way to overcome this is to utilize technology for making wafers. Information regarding technology for making animal feed wafers in Indonesia is still limited. This paper reviews a number of studies that discuss the development of wafer processing technology, types of wafers, the main components of wafer compilers, wafer manufacturing processes, reactions that occur during wafer manufacturing, nutrient quality of various wafers, and the results of research on the use of wafers for feed livestock. Wafers are feeds that are processed using heat and pressure, so that a solid, compact, and high density product is formed. Feed wafer technology is a modification of cube and block feed. Wafers are divided into feed wafers, feed supplement wafers, and complete feed wafers. Feed wafers can be used instead of concentrates. Feed supplement wafers are high in energy and protein. Complete feed wafers contain energy, protein, fiber, and complete minerals that have been adapted to the daily nutritional needs of livestock. Feed wafer processing technology can be one of the strategies to provide feed with a constant composition of nutrients throughout the season and increase production and feed efficiency.

Bespoke GelFoam Wafers: A Practical and Inexpensive Alternative to Oxycel for Hemostasis during Neurosurgery.

Background:Since the beginning of neurosurgery, intraoperative parenchymal bleeding has been a major problem. Achievement of hemostasis is the endpoint of any cranial or spinal neurosurgical exercise and is mandatory to avoid postoperative hematomas which mar the ultimate outcome of the surgery. Several biosurgical agents are used to achieve this goal. Agents such as oxidized cellulose, gelatin foam, fibrillar collagen, fibrin sealants, and antifibrinolytic agents are used, each having a different mechanism of action.Materials and Methods:The authors describe a simple technique for substituting oxidized regenerated cellulose (Surgicel) for lining the surgical cavities after excising brain lesions, with customized gelfoam wafers fashioned on the surgical trolley. This has been used in over 8000 cases with excellent hemostatic results over the last 25 years. No complications are noted with use of these wafers.Results:In a randomized trial done by us, similar hemostatic effect was found between oxycel and the gelfoam wafers described by us with satisfactory outcomes of surgeries. No previous use of such custom-fashioned wafers has been described for neurosurgical hemostasis in the literature.

Potential and Challenges of Diamond Wafer Toward Power Electronics

To achieve a 50% worldwide reduction of CO2by the middle of this century, development of energy saving power device technology using wide bandgap materials is urgently needed. Diamond is receiving increasing attention as a next generation material for wide bandgap semiconductors owing to its extreme characteristics. Research studies investigating large wafers, low resistivity, and low dislocation have accelerated. This study targets the use of wafers for power electronics applications, and the required machining technologies for diamond, including wafer shaping, slicing, and surface finishing, are introduced.

Development of wafers with lowered glycemic index

The negative impact an organism is made by lack of culture of food of the population and low physical activity. It leads to violations of carbohydrate and lipidic exchange, development of obesity, diabetes, cardiovascular and other diseases. Relevance of development of foodstuff, in particular – the confectionery promoting decrease in risk of developing of such pathologies is proved. A research objective – development of a compounding of wafers with the lowered glycemic index. As an object of a research the wafers baked in house conditions are chosen. In work various characteristics are analysed (hygroscopicity, a cariogenicity sweet degree, power value, a glicemic index and a glycemic response) the sweetening substances, the choice of fructose as sugar substitute for production of wafers with the lowered glycemic index is reasonable. By optimization of a compounding of wafers the amount of sugar was replaced with amount of sweetener, equivalent sweet. As a result of predesigns the interval of a variation of amount of the fructose entered into a compounding of wafers is established. Further assessment of the indicators of quality forming consumer demand of products – appearance, taste, a smell, existence of a crunch is carried out. Humidity of the received wafers after their production and in the course of storage is also investigated. Decrease in a glycemic index was fixed by amount of glucose in blood. Its measurements saw by means of the glucose meter on an empty stomach and after the use of wafers to a complete recovery of level of sugar in blood. The confectionery made the optimized compounding practically doesn't differ caloric content from a control sample, and glucose level in blood after their use about 20% below.

Improved organic acid purification through wafer enhanced electrodeionization utilizing ionic liquids

Purification of organic acids through electrodialysis has been studied extensively over the past two decades; however, little work has been done on attempting to utilize electrodialysis for solvent replacement for improved acid recovery. This study presents the use of ionic liquids as a secondary electrodialysis solvent in order to transport organic acids from a water phase into an ionic liquid phase. Specifically, the use of wafer enhanced electrodeionization techniques with ionic liquids is investigated to improve system performance. Incorporation of ionic liquids allows continuous separation with high solvent recyclability and low operation hazards. Through the use of wafer technology, current efficiencies reached 37–90% with energy consumption rates of approximately 1.25–2.80kWh/kg acid recovered. Improved separation efficiencies were due to improved electrical conductance of the solutions provided by addition of the resin wafer into the cell compartments. The influence of solution conductivity and current density on separation performance was also studied. It was found that high current densities resulted in higher ion and water transport. Solubility of products, ionic liquid solution characteristics, and water contamination were also found to have a significant impact on current efficiency and power consumption. Through this project, separation of organic acids into ionic liquids with low energy requirements and high separation efficiencies was achieved.

Evaluation of post-operative complications associated with repeat resection and BCNU wafer implantation in recurrent glioblastoma

Patients with glioblastoma treated with BCNU wafer implantation for recurrence frequently receive frontline chemoradiotherapy with temozolomide as part of the Stupp protocol. A retrospective investigation was conducted of surgical complications in a cohort of these patients treated at a single institution. We searched our institutional database for patients treated between January 2006 and October 2012 who had recurrent glioblastoma previously treated with open surgery followed by the Stupp protocol and then underwent repeat resection with or without BCNU wafers for recurrent disease. Rates of select post-operative complications within 3 months of surgery were estimated. We identified 95 patients with glioblastoma who underwent resection followed by the Stupp protocol as frontline treatment. At disease recurrence (first and second recurrence), 63 patients underwent repeat resection with BCNU wafer implantation and 32 without implantation. Generally, BCNU wafer use was associated with minor to moderate increases in rates of select complications versus non-implantation-wound healing abnormalities (14.2 vs. 6.2 %), cerebrospinal fluid leak (7.9 vs. 3.1 %), hydrocephalus requiring ventriculoperitoneal shunt (6.3 vs. 9.3 %), chemical meningitis (3.1 vs. 0 %), cerebral infections (3.1 vs. 0 %), cyst formation (3.1 vs. 3.1 %), cerebral edema (4.7 vs. 0 %), and empyema formations (1.5 vs. 0 %). Performance status was well maintained post-operatively in both groups. Median progression-free survival from the time of first recurrence was 6.0 and 5.0 months, respectively. The use of the Stupp protocol as frontline therapy in patients with glioblastoma does not preclude the use of BCNU wafers at the time of progression.

Risk factors and outcomes associated with surgical site infections after craniotomy or craniectomy

Many studies that have evaluated surgical site infections (SSIs) after craniotomy or craniectomy (CRANI) did not use robust methods to assess risk factors for SSIs or outcomes associated with SSIs. The authors conducted the current study to identify risk factors for SSIs after CRANI procedures and to evaluate outcomes attributed to SSIs. The authors performed a nested case-control study of patients undergoing CRANI procedures between 2006 and 2010 at the University of Iowa Hospitals and Clinics. They identified 104 patients with SSIs and selected 312 controls. They collected data from medical records and used multivariate analyses to identify risk factors and outcomes associated with SSIs. Thirty-two percent of SSIs were caused by Staphylococcus aureus, 88% were deep incisional or organ space infections, and 70% were identified after discharge. Preoperative length of stay (LOS) ≥ 1 day was the only significant patient-related factor in the preoperative model (OR 2.1 [95% CI 1.2-3.4]) and in the overall model (OR 1.9 [95% CI 1.1-3.3]). Procedure-related risk factors that were significant in the overall model included Gliadel wafer use (OR 6.7 [95% CI 2.5-18.2]) and postoperative CSF leak (OR 3.5 [95% CI 1.4-8.5]). The preoperative SSI risk index, including body mass index, previous brain operation, chemotherapy on admission, preoperative LOS, procedure reason, and preoperative glucose level, had better predictive efficacy (c-statistic = 0.664) than the National Healthcare Safety Network risk index (c-statistic = 0.547; p = 0.004). Surgical site infections were associated with increased LOS during the initial hospitalizations (average increase of 50%) or readmissions (average increase of 100%) and with an increased risk of readmissions (OR 7.7 [95% CI 4.0-14.9]), reoperations (OR 36 [95% CI 14.9-87]), and death (OR 3.4 [95% CI 1.5-7.4]). Surgeons were able to prospectively assess a patient's risk of SSI based on preoperative risk factors and they could modify some processes of care to lower the risk of SSI. Surgical site infections substantially worsened patients' outcomes. Preventing SSIs after CRANI could improve patient outcomes and decrease health care utilization.

Solidly mounted BAW resonators with layer-transferred AlN using sacrificial Si surfaces

We present a new method to manufacture solidly mounted bulk acoustic wave resonators. This new process introduces the use of wafer bonding techniques and sacrificial surface removal to manufacture solidly mounted resonators having special properties. With the proposed process, Aluminum Nitride (AlN) thin films are obtained having exceptional c-axis crystal orientation with XRD rocking curve FWHM of 1.36° and material electromechanical coupling constant of 6.8% exceeding that of the epitaxial AlN electromechanical coupling constant. Fully functional single-mask resonators were successfully fabricated with this process working around 2.35 GHz and enjoying Q-values as high as 1300.

Wafer Bonding Technologies in Industrial MEMS Processing - Potentials and Challenges

This paper will give an overview of the use of wafer bonding technologies, in particular, semiconductor direct bonding, glass frit bonding and anodic bonding, in the manufacture of MEMS devices. The potential of these processes is illustrated, as well as the challenges of integrating the bonding process into industrial processing.

Adhesion quantification methods for wafer bonding

Abstract Integrated circuit technology and its later development, microsystem technology, make good use of wafer bonding. An increased interest in bond adhesion quantification can be anticipated when wafer bonding is optimized for complex microelectro-mechanical systems where the bonding process must take every other component into consideration when it comes to cost, temperature budget and process compatibility. Adhesion quantification methods for evaluation of bonded brittle material, especially direct wafer bonded, are reviewed in this paper. The most commonly utilized methods, namely the double cantilever beam, tensile, chevron and blister test methods, are thoroughly covered and miscellaneous techniques are mentioned. The physics background and modeling presented by different authors are examined. Based on models and experiences made in neighboring research fields improvements are suggested. Practical capabilities and limitations and origin and mitigation of measurement errors are addressed. Experimental foundation on fundamental knowledge in solid mechanics and the statistical nature of brittle fracture behavior is emphasized. The methods’ adequacy are compared and ranked for three types of uses: general understanding, bonding process optimization and quality control. It is shown that the quality of all commonly used methods for adhesion quantification of wafer bonding can be dramatically improved by small means.

InP-InGaAsP wafer-bonded vertically coupled X-crossing multiple channel optical add-drop multiplexer

A vertically coupled InP-InGaAsP crossed waveguide optical add-drop multiplexer has been realized through the use of wafer bonding. Designed for signals in the 1550-nm range, this novel device requires only a single epitaxial growth and illustrates the use of vertical optical interconnects for the three dimensional routing of optical signals. To our knowledge, it is also one of the first optical vertically coupled devices with no horizontally coupled counterpart.

High frequency properties of silicon-on-insulator and novel depleted silicon materials

High frequency properties of substrates such as substrate losses and cross-talk were investigated for silicon-on-insulator (SOI) materials and for a novel depleted silicon material. Simulations were made to reveal high frequency properties of SOI MOSFETs made on fully depleted SOI materials of different substrate resistivities. The substrate resistivity was varied from 0.01 Ω cm to 10 kΩ cm . It was found that the high frequency properties of intrinsic transistors were independent of the substrate resistivity, but a system consisting of both active and passive components showed reduced cut-off frequency, f T, and maximum oscillation frequency, f max, for low substrate resistivities. The obtained information on the importance of the silicon substrate resistivity has been used to manufacture a depleted silicon material by use of wafer bonding. The novel material is intended as substrate for high frequency applications. The space charge regions surrounding a bonded silicon/silicon interface deplete the silicon thereby reducing substrate losses at high frequencies. The novel material has been characterised electrically for frequencies up to 40 GHz using metal transmission lines and cross-talk structures on its surface. The measurements have been compared to similar measurements on bulk silicon, SIMOX and quartz substrates. The depleted region of the novel material shows up in its electrical characteristics.

Surface energy as a function of self-bias voltage in oxygen plasma wafer bonding

A limitation in the use of wafer bonding has been the necessity for high-temperature annealing after contacting the wafers at room temperature. In this paper, we try to find the highest surface energy as a function of self-bias voltage in oxygen plasma-activated wafer bonding, in order to achieve a low-temperature bonding process. The bonding was performed in situ the vacuum chamber. It was found that oxygen plasma has a smoothing effect on the surface roughness, rather independent of the plasma self-bias. However, a moderate self-bias voltage proved to give the highest surface energy for the bonded wafers, both at room-temperature and after annealing at 200°C. We believe that this is due to the fact that a moderate self-bias is the most efficient in removing surface contaminants, like water and hydrocarbons. It was also found that even after annealing at higher temperatures, 480°C and 720°C, the plasma-bonded wafers showed higher surface energy values than wafers bonded in ambient air. This investigation was focused on low-effect plasmas, <200 W, keeping the induced plasma damages at a minimum.

The role of interstitial BCNU chemotherapy in the treatment of malignant glioma

BACKGROUND Use of interstitial BCNU wafers in the treatment of malignant glioma is currently a controversial topic among neurosurgeons. Initial clinical studies indicated implantation of BCNU wafers into the postoperative tumor bed to be an acceptably safe, partially effective treatment for glioblastoma multiforme. Yet a more recent study has put the efficacy of this treatment in doubt, and there are potential complications associated with BCNU wafer use. OBJECTIVE This article presents a review of the information presently available on BCNU wafers—both pro and con—to aid in the clinical decision-making process. The article focuses on studies of clinical efficacy (for initial use as well as in the setting of recurrent tumor), complications associated with BCNU wafers, and the experimental data, particularly related to BCNU penetration into the brain. RESULTS Animal studies and computer simulations have shown that the depth of penetration of BCNU from wafers is limited. Yet in actual clinical use, the interstitial pressure within the wafer-laden tumor bed might be higher, convective flow greater, and delivery of BCNU to the brain more significant than predicted. CONCLUSION Based on current information, use of interstitial BCNU wafers continues to be an option for treating malignant glioma. Additional clinical studies of BCNU wafers are currently underway.

Use of wafer maps in integrated circuit manufacturing

A wafer map identifies the locations of defective integrated circuits (chips) on a silicon wafer and provides important spatial information. The wafer yield is a useful measure of the process quality, but other features are necessary to account for. Careful statistical analysis addressing the spatial information in the wafer map is necessary in order to monitor the quality of the manufacturing process, and identify/eliminate fault sources with assignable causes. We discuss simple descriptive analyses of wafer map data, as well as formal statistical methods, based on three different models that account for different spatial patterns. In particular, the models support the observed phenomenon that the faults are distributed non-uniformly across the wafer, by allowing the fault probability to vary across the wafer, and allowing faults at adjacent locations to be statistically dependent.

WAFERS AND WAFER SEALS: HISTORY, MANUFACTURE, AND CONSERVATION

Summary Wafers are thin, flat, baked adhesive discs which were used for a variety of sealing and joining functions. In use as early as 1635, wafers were largely displaced by the end of the 19th century by pre-gummed envelopes and seal papers. Recipes for wafers called for fine white flour, isinglass, glair. yeast and a colorant, typically vermillion. Other pigments such as indigo, verdigris, gamboge and red lead were also used. The ingredients were mixed into a paste, diluted with a gum solution, and baked on a metal sheet, or between the faces of a ‘wafer iron’. After cooling, the wafers were cut out of the sheets by hand with round steel punches. Wafers were produced in different sizes for use as adhesive joins or for affixing paper-covered seals on deeds, indentures or other official documents, and are often mistaken for resinous (sealing) wax seals. The use of wafers for repair of torn paper and for mounting of photographs has been observed. The brittleness of wafers can result in breakage and loss, a...

Soil Moisture Conditions under Pastures of Cool-Season and Warm-Season Grasses

Highlight The season of active growth and wafer use by warm-season grasses is about five months, May through September, compared with seven to eight months for cool-season grasses. The,re was less wafer in fhe soil in midspring each year under cool-season than under warm-season grasses. Consequently, the cool-season pastures suffered from midsummer drought more offen than did warmseason pastures.