CN110859650A

CN110859650A - Anastomosis nail

Info

Publication number: CN110859650A
Application number: CN201911180851.8A
Authority: CN
Inventors: 于亚川; 王青川; 魏翔; 杨柯
Original assignee: Suzhou Senfeng Medical Equipment Co Ltd
Current assignee: Suzhou Senfeng Medical Equipment Co Ltd
Priority date: 2019-11-27
Filing date: 2019-11-27
Publication date: 2020-03-06

Abstract

The application discloses anastomosis nail, this anastomosis nail include the nail body and set up respectively in two nail legs at nail body both ends, and the nail leg is including keeping away from the tail section of nail body and the main part section that borders on the nail body, and the part that the main part section of at least one nail leg borders on the tail section is the arc, and the tail section of two nail legs is parallel to each other. Through the mode, the injury of the anastomosis nail to the tissue can be reduced, and the fixity is improved.

Description

Anastomosis nail

Technical Field

The application relates to the technical field of biomedical treatment, in particular to an anastomosis nail.

Background

With the development of medical science and technology, the suturing of human tissues or organs in the operation has been changed from the original manual suturing by needles and threads to the suturing by means of medical anastomats and staples. The medical anastomat is used for suturing, the operation is convenient, the anastomosis is safe, and the wound caused by the anastomosis is small. The influence of the anastomotic nail on body tissues and wounds needs to be considered when the anastomotic nail is designed, the anastomotic nail strives to achieve small tissue damage, is friendly to the body, has good fixation at the initial fixing stage so as to facilitate the healing of the wounds, and is easy to fall off/degrade after the healing of the wounds. The aim can be achieved by researching the structure and the material of the anastomosis nail, and the anastomosis nail has a simple structure and limited design space, so that the current research is mostly focused on the material of the anastomosis nail.

The commonly used materials for the anastomosis nail at present comprise titanium alloy, magnesium alloy, iron alloy and the like. The titanium alloy anastomosis nail has good corrosion resistance and good fixity, but the titanium alloy anastomosis nail can be left in human tissues or organs for a long time after being sutured, is not easy to degrade/fall off, and can cause inflammation of surrounding tissues after a long time. The magnesium alloy anastomosis nail can be biodegraded, but the degradation speed is too high, the wound is not completely healed, the magnesium alloy anastomosis nail begins to degrade, the fixity is poor, and the wound is easily wounded again. The ferroalloy anastomosis nail has better support property and biocompatibility, but has slower degradation speed and longer time for degradation in vivo. Therefore, a better staple has yet to be developed.

Disclosure of Invention

The main technical problem who solves of this application provides an anastomosis nail, can reduce the damage of anastomosis nail to the tissue, improves the fixity.

In order to solve the technical problem, the application adopts a technical scheme that: the utility model provides an anastomosis nail, this anastomosis nail includes the nail body and sets up respectively in two nail legs at nail body both ends, and the nail leg is including keeping away from the tail section of nail body and the main part section that borders on the nail body, and the part that the main part section of at least one nail leg borders on the tail section is the arc, and the tail section of two nail legs is parallel to each other.

The main body section comprises a first main body section adjacent to the nail body and a second main body section adjacent to the tail section, the second main body section is arc-shaped, the cross-sectional area of the first main body section is smaller than that of the second main body section, and/or the cross-sectional area of the first main body section is smaller than that of the nail body.

Wherein, the connection part of the nail body and the nail legs is in arc transition, and/or the connection part of the main body section and the tail section is in arc transition.

Wherein the total length of the two nail legs is different; and/or the length of the body sections of the two legs is different; and/or the length of the tail sections of the two legs may be different.

Wherein the cross section of the main body section is circular or elliptical; and/or the end of the tail section is provided with a guide edge.

Wherein, the anastomosis nail is integrally formed by biodegradable iron alloy materials.

Wherein the biodegradable ferroalloy comprises 0.25-0.70% of nitrogen and 15.00-35.00% of manganese.

Wherein the biodegradable ferroalloy comprises 0.35-0.55% of nitrogen and 18.00-25.00% of manganese.

Wherein the biodegradable iron alloy consists of 0.25-0.70% of nitrogen, 15.00-35.00% of manganese, less than 0.01% of sulfur, less than 0.025% of phosphorus and the balance of iron.

Wherein the microstructure of the biodegradable ferroalloy is single-phase austenite.

The beneficial effect of this application is: be different from prior art's condition, the staple that this application provided, the back end of two nail legs is parallel to each other, can make the staple at the in-process of sewing up the entering tissue, and the direction of going ahead is stable, and the atress is even, sews up accurately, has better penetrability to the tissue, and then can reduce the damage to the tissue. The main body section part of the staple leg adjacent to the tail section is arc-shaped, so that after the anastomotic staple enters tissues, an inward bending stress is generated, the anastomotic staple is conveniently bent and formed inwards, the forming resistance is reduced, and the forming stability is improved.

Drawings

Fig. 1 is a schematic flow chart of a method for preparing a biodegradable ferroalloy according to an embodiment of the present disclosure;

FIG. 2 is a schematic flow chart of a method for preparing a biodegradable ferroalloy according to another embodiment of the present disclosure;

FIG. 3 is a schematic structural view of a staple according to one embodiment of the present application;

FIG. 4 is a schematic structural view of a staple after formation in one embodiment of the present application;

FIG. 5 is a schematic structural view of a staple according to another embodiment of the present application;

FIG. 6 is a schematic structural view of a staple according to yet another embodiment of the present application;

FIG. 7 is a schematic structural view of a staple in accordance with yet another embodiment of the present application;

fig. 8 is a schematic structural view of a staple according to yet another embodiment of the present application.

Detailed Description

In order to make the purpose, technical solution and effect of the present application clearer and clearer, the present application is further described in detail below with reference to the accompanying drawings and examples.

The application provides a biodegradable iron alloy which has high nitrogen content and is matched with proper manganese content, so that the obtained iron alloy has excellent corrosion rate and mechanical property.

In one embodiment, the biodegradable iron alloy provided by the present application includes 0.25-0.70% nitrogen (N) and 15.00-35.00% manganese (Mn). The nitrogen content may be 0.28%, 0.33%, 0.36%, 0.48%, 0.52%, 0.61%, 0.64%, etc., and the manganese content may be 16.00%, 20.00%, 22.12%, 24.45%, 28.00%, 30.67%, 32.13%, etc.

Further, the biodegradable iron alloy comprises 0.35-0.55% of nitrogen, 18.00-25.00% of manganese, and the balance of iron, sulfur with the content of less than 0.01% and phosphorus with the content of less than 0.025%.

The corrosion rate of pure iron in a body is too low to well meet the requirement of an implant on the corrosion rate, the corrosion rate of the iron alloy can be improved by adding the manganese element, and the corrosion rate of the iron alloy can be regulated and controlled to a certain extent by adjusting the content of the manganese element. Generally, increasing the content of manganese element can increase the corrosion rate, but it should be controlled that the amount of manganese produced by degradation cannot exceed the basic amount of human metabolism.

The addition of nitrogen can affect the stability of the austenitic microstructure of the iron alloy on one hand, and can improve the corrosion rate and the mechanical property of the iron alloy on the other hand.

The austenitic iron alloy has some advantages in mechanical properties due to greater plastic deformation between the yield point and the ultimate failure experienced during processing, and the low magnetic susceptibility austenitic iron alloy does not interfere with Magnetic Resonance Imaging (MRI), facilitating subsequent medical examination. Therefore, austenitic alloys are more readily selected for use in medical implants.

The inventors of the present application have found that increasing the nitrogen content in an iron alloy can promote the formation of an austenitic iron alloy. The ferroalloy provided by the application contains 0.25-0.70% of nitrogen, so that the microstructure of the ferroalloy is single-phase austenite, and the ferroalloy has better magnetic compatibility.

Under the influence of factors such as a preparation process and the like, the content of nitrogen element in the existing iron alloy is low (generally lower than 0.2%), and the inventor of the application also researches and discovers that the content of manganese element can influence the content of nitrogen element. To a certain extent, increasing the content of manganese can increase the content of nitrogen, which can make the addition of nitrogen difficult if the content of manganese is too low. The contents of the manganese element and the nitrogen element can influence the corrosion rate of the iron alloy, and the inventor of the application finds that when the iron alloy contains 0.25-0.70% of nitrogen and 15.00-35.00% of manganese, the iron alloy has excellent corrosion rate and stable austenitic structure.

In one embodiment, the biodegradable iron alloy provided by the application consists of 0.25-0.70% of nitrogen, 15.00-35.00% of manganese, less than 0.01% of sulfur, less than 0.025% of phosphorus and the balance of iron. That is, the iron alloy has only two doping elements of nitrogen and manganese except a small amount of inevitable impurities. The simple element alloying system is beneficial to regulating and controlling the performance of the ferroalloy, and the doped manganese and nitrogen are non-toxic in vivo by degradation and dissolution, so that the introduction of more elements is avoided, and the influence of the action among multiple elements is prevented.

Referring to fig. 1, fig. 1 is a schematic flow chart of a method for preparing a biodegradable iron alloy according to an embodiment of the present disclosure. In this embodiment, smelting an iron alloy in a nitrogen atmosphere to add nitrogen element to the iron alloy includes the following steps:

s110: providing a ferroalloy raw material.

Wherein the ferroalloy raw material comprises 15.00-35.00% of manganese element.

S120: adding the ferroalloy raw material into a smelting furnace, smelting in a nitrogen atmosphere until the content of nitrogen in the ferroalloy reaches 0.25-0.70%, and casting to form a cast ingot.

Wherein, the smelting can be carried out under the atmosphere of normal pressure or high-pressure nitrogen with the pressure of 0.2MPa to 1.5 MPa.

S130: and forging the cast ingot to obtain a forged piece.

The ingot can be forged after being subjected to heat preservation for 0.5-2 hours at 1050-1200 ℃ to obtain a forged piece, and the forged piece can be rolled into various shapes according to requirements, such as a round bar shape.

S140: and carrying out heat treatment on the forged piece to obtain the biodegradable iron alloy.

Wherein the temperature and time of the solution treatment affect the microstructure of the resulting ferroalloy. In the embodiment, the conditions of the solution treatment are 900-1050 ℃, the temperature is kept for 0.5-2.0 hours, and the biodegradable iron alloy is cooled in air or water to room temperature, so that the microstructure of the biodegradable iron alloy is single-phase austenite under the conditions.

Referring to fig. 2, fig. 2 is a schematic flow chart of a method for preparing a biodegradable iron alloy according to another embodiment of the present disclosure. In this embodiment, the nitriding treatment is performed on the iron alloy to dope nitrogen element into the iron alloy, and the method comprises the following steps:

s210: providing a ferroalloy raw material.

S220: adding the ferroalloy raw material into a smelting furnace for smelting, casting to form an ingot, and forging the ingot to obtain a forged piece.

S230: and nitriding the forged piece until the content of nitrogen in the iron alloy reaches 0.25-0.70%.

In one embodiment, the forging may be nitrided by high temperature nitriding. Placing the forging piece into a high-temperature nitriding furnace, controlling the nitriding temperature of the high-temperature nitriding furnace to be 350-450 ℃, and introducing high-purity nitrogen (N) into the high-temperature nitriding furnace₂) Or ammonia (NH)₃) Or a mixture of the two, maintaining the atmosphere pressure of the nitriding atmosphere at 0.1-1.0 MPa, preserving the heat for 3-8 h, fully nitriding the forged piece, and then putting the nitrided forged piece into an annealing furnace for annealing to obtain the biodegradable iron alloy.

In another embodiment, the forging may be nitrided by ion nitriding. Putting the forging part into a vacuum chamber, connecting the forging part with the negative electrode of a bias power supply, vacuumizing to 2-10 Pa, starting the bias power supply to generate stable glow discharge on the surface of the forging part, wherein the voltage is between 400 and 700W, and slowly introducing N after the discharge is stable₂And H₂Mixed gas of (3) or NH₃Or H₂And NH₃The gas mixture is kept stable at 40-150 Pa, glow discharge is maintained, the temperature of the forging part is raised to 500-550 ℃, and nitriding is maintained for 2-4 h.

In the embodiment, the nitriding amount of the alloy can be increased by regulating and controlling the manganese content in the ingot, and nitrogen atoms are uniformly distributed; and the nitriding rate can be improved, and the nitriding efficiency is further improved.

The present application will now be illustrated and explained by means of several groups of specific examples and comparative examples, which should not be taken to limit the scope of the present application.

The iron alloy raw materials of the respective examples and comparative examples were prepared, and the specific raw material components and proportions are detailed in table 1.

Adding the ferroalloy raw material into a smelting furnace, and smelting under corresponding conditions to obtain a ferroalloy sample.

And (3) carrying out various performance tests on the obtained iron alloy sample, wherein the test method and the standard are as follows:

1. corrosion rate detection

Each ferroalloy sample was immersed in physiological saline at 37 ℃ for 7 days, and the weight loss results were measured, and the results obtained are detailed in table 2.

2. Microstructure detection

The microstructure of each ferroalloy sample was observed using a metallographic microscope and the results are detailed in table 2.

3. Tensile mechanical property detection

The tensile mechanical properties of each ferroalloy sample were measured using a universal mechanical tester, and the results are detailed in table 2.

Table 1: major chemical composition (wt.%) of biodegradable ferroalloy

Material	Mn	N	C	S	P	Fe
							Example 1	18	0.31	0.014	0.013	0.008	Balance of
Example 2	21	0.40	0.010	0.014	0.009	Balance of
							Example 3	24	0.45	0.020	0.008	0.008	Balance of
Example 4	28	0.56	0.009	0.010	0.007	Balance of
							Example 5	33	0.68	0.015	0.013	0.005	Balance of
Example 6	0.92	0.41	0.011	0.013	0.006	Balance of
							Comparative example 1	0.95	-	0.017	0.018	0.008	Balance of
Comparative example 2	16	0.21	0.013	0.013	0.010	Balance of
							Comparative example 3	0.87	0.2	0.016	0.011	0.006	Balance of

Table 2: corrosion rate, microstructure and mechanical properties of biodegradable ferroalloys

As can be seen from the results in table 2, the biodegradable iron alloys of examples 1 to 5 of the present application have not only excellent corrosion rate, but also stable austenitic structure and excellent mechanical properties. The proper manganese and nitrogen contents and the corresponding preparation and heat treatment processes are the key points that the biodegradable iron alloy provided by the application can have a stable austenitic structure and excellent corrosion rate and mechanical properties.

The content of manganese has a large influence on the corrosion rate. The comparative example 1 has the lowest corrosion rate due to the lower manganese content.

The content of manganese also has a great influence on the content of nitrogen. The lower manganese content in the compositions of comparative examples 2 and 3 resulted in difficulty in adding nitrogen and a decrease in nitrogen content.

The content of nitrogen has a great influence on the corrosion rate and microstructure. The composition of comparative example 1 had no nitrogen element added thereto, and had a microstructure of ferrite. The compositions of comparative examples 2 and 3 have low nitrogen content, and the microstructure of the compositions is austenite and martensite two-phase structure.

The embodiments 1 to 5 have high manganese and nitrogen contents, and can simultaneously obtain a stable austenite structure, an excellent corrosion rate and excellent mechanical properties.

In summary, in order to obtain a stable austenitic structure, an excellent corrosion rate and excellent mechanical properties, the contents of manganese and nitrogen are balanced, and preparation and treatment processes are combined to make the iron alloy have an excellent corrosion rate and a stable austenitic structure.

Wherein the change of the element content will certainly affect the subsequent heat treatment process, which will in turn determine the structural properties of the ferroalloy. Therefore, it can be seen from the above results of examples and comparative examples that the excellent corrosion rate and the stable austenitic structure of the iron alloy can be achieved only when the contents of the respective elements in the iron alloy material and the heat treatment process are complementary and matched with each other within a certain suitable range. The adjustment of the element component content and the heat treatment parameters requires the inventors of the present application to make creative thinking for analyzing and judging the result of each experimental condition, and to find out what the cause influencing the experimental result is (for example, a certain experimental result shows that the obtained structure is austenite and martensite, and the analysis is caused by the change of the element content or the change of the heat treatment process parameters), and the following experimental direction can be determined by referring to the experimental phenomenon, the literature information and the like, so as to verify the analysis and judgment, further adjust the experimental direction again, and find out a more appropriate experimental scheme with a smaller number of experimental times, so as to obtain the material formula and the process parameters.

According to the scheme, the biodegradable iron alloy provided by the application has excellent corrosion rate, stable austenite tissue structure and excellent mechanical property, and can be used for manufacturing medical implants, such as implants for anastomosis nails, nerve conduits, stents and the like. The application does not limit the type, structure and the like of the implant which is specifically manufactured.

Fig. 3 is a schematic structural view of a staple according to an embodiment of the present application. In this embodiment, the staple includes a body 10 and two legs 20 respectively disposed at both ends of the body 10, the legs 20 include a tail section 220 distant from the body 10 and a body section 210 adjacent to the body 10, a portion 211 of the body section 210 of at least one leg 20 adjacent to the tail section 220 is curved, and the tail sections 220 of the two legs 20 are parallel to each other.

In this embodiment, the back end section through setting up two nail legs is parallel to each other, can make the anastomotic nail at the in-process of sewing up the entering tissue, and the direction of going ahead is stable, and the atress is even, sews up accurately, has better penetrability to the tissue, and then can reduce the damage to the tissue. Or the tail sections of the two nail legs can be arranged to be linear, so that the tail sections are ensured to have no radian. As shown in FIG. 3, the tail sections of the two staple legs are arranged in parallel along the vertical direction, and the arrangement can ensure that the staples can enter tissues linearly and cannot be deviated. The length of the tail section can be various types to adapt to different tissues to be sutured.

In the embodiment, the main body section part of the staple leg adjacent to the tail section is arranged into the arc shape, so that the staple can have an inward bending stress after entering the tissue, the inward bending forming of the staple is facilitated, the forming resistance is reduced, and the forming stability is improved.

By arranging the portions of the main body segment in an arc and the tail segments in parallel, less damage to tissue is caused than if the tail segments were arranged directly in an arc. If direct set the tail-end into the arc, when sewing up the entering tissue, the direction of going forward is unstable, and the off tracking that easily slides leads to sewing not accurate, can deviate wound area even, causes unnecessary damage to peripheral tissue, and the fixity after the shaping also can reduce. And in the setting in this application, the back end is parallel, and the direction when guaranteeing to get into the tissue is stable, presents the bending stress that the arc brought again after getting into the tissue, improves the stability of taking shape.

Referring to fig. 4, fig. 4 is a schematic structural view of a formed staple according to an embodiment of the present application. After the staples penetrate through the tissue to form, the staples are generally in a 'B' shape, and the 'B' shape can be propped open by the tissue along with the movement of a patient or the proliferation of peripheral tissues, so that the anastomotic orifice is broken, and the like. By arranging the portions of the body segments in an arcuate shape, stresses exist during forming as opposed to a linear leg, making the forming more stable. Meanwhile, the bending radian is large, so that the B-shaped hollow space is relatively large, more buffer spaces are provided, the acting force of tissues on the anastomosis nail is reduced, and the probability of being propped open is reduced; meanwhile, the effect of the anastomosis nail on tissues is reduced, and the probability of inflammation and tissue hyperplasia is reduced.

Referring to fig. 5, fig. 5 is a schematic structural view of a staple according to another embodiment of the present application. In this embodiment, the junction 231 of the shank 10 and the legs 20 transitions in a circular arc and/or the junction 232 of the body section 210 and the tail section 220 transitions in a circular arc. Through setting up the circular arc transition, can avoid the junction to have the edges and corners to cause the amazing to the tissue, reduce the discomfort of postoperative. The forming preparation of the anastomosis nail can be facilitated, the strength of the anastomosis nail is enhanced, and the fracture of the anastomosis nail caused by stress concentration at the joint is prevented.

In one embodiment, the end of the tail section of the leg is provided with a guide edge. If the tail section is made into a 40-45-degree cutting tip, the end part of the tail section is provided with a pointed tip, so that the anastomosis nail can easily penetrate into tissues, the wound is reduced, and the pain caused by suturing is reduced. By arranging the guide blade, the entering direction of the anastomosis nail can be stabilized.

In one embodiment, the body section of the staple legs has a circular or elliptical cross-sectional shape. By providing the main body section in a cylindrical shape (circular or oval in cross-sectional shape), there is no irritation to the tissue, less discomfort after surgery, and less damage to the tissue during entry into the tissue. Meanwhile, the long-time slow pushing action of the tissue on the nail body is facilitated, so that the anastomosis nail automatically falls off, and the wound healing is accelerated.

Referring to fig. 6, fig. 6 is a schematic structural view of a staple according to yet another embodiment of the present application. In this embodiment, the body section 210 includes a first body section 212 adjacent the shaft 10 and a second body section 211 adjacent the tail section 220, the second body section 211 being arcuate.

Wherein the cross-sectional area of the first body segment 212 is smaller than the cross-sectional area of the second body segment 211 and/or the cross-sectional area of the first body segment 212 is smaller than the cross-sectional area of the shank 10. By providing the first body segment 212 with thinner opposing sides, the thinner first body segment 212 is readily absorbed and degraded by tissue as the wound heals, breaking the staple into two portions, namely a staple body and a staple leg, increasing the rate of erosion.

Referring to fig. 7 and 8 in combination, fig. 7 is a schematic structural view of a staple according to still another embodiment of the present application, and fig. 8 is a schematic structural view of a staple according to still another embodiment of the present application. The staple legs at two ends of the conventional anastomotic staples are symmetrically arranged, but due to the difference of tissues to be anastomosed, the shapes of wounds are different, the tissue forms at two sides of the wounds may be different, and at the moment, the symmetrical anastomotic staples have the problem of unbalanced stress after entering the tissue to be formed, so that the fixation is poor. Therefore, the asymmetric anastomosis staple can be arranged according to the requirement, the staple legs at two ends have different lengths (shown in fig. 7), and particularly the total length (the sum of the lengths of the main body section and the tail section) of the two staple legs can be different; and/or the length of the body sections of the two legs is different; and/or the length of the tail sections of the two legs may be different. The shape of the nail legs at the two ends can be different (shown in fig. 8), the thickness of the nail legs at the two ends can be different, and the like, and the shape is not limited herein.

In one embodiment, the staple is integrally formed by die-casting a biodegradable iron alloy, and specifically, the staple can be made of the biodegradable iron alloy in any one of the above embodiments. The ferroalloy anastomosis nail does not interfere Magnetic Resonance Imaging (MRI), facilitates later medical examination, and can track and observe the position state of the anastomosis nail. The ferroalloy anastomosis nail has excellent corrosion rate and can meet the requirements of the anastomosis nail.

According to the scheme, the anastomosis nail is improved in the aspects of structure and material, and the anastomosis nail with excellent performance is manufactured.

The above description is only for the purpose of illustrating embodiments of the present application and is not intended to limit the scope of the present application, and all modifications of equivalent structures and equivalent processes, which are made by the contents of the specification and the drawings of the present application or are directly or indirectly applied to other related technical fields, are also included in the scope of the present application.

Claims

1. The utility model provides a staple, its characterized in that, staple include the nail body with set up respectively in two staple legs at nail body both ends, the staple leg is including keeping away from the tail section of nail body with adjoin the main part section of nail body, wherein, at least one the staple leg the main part section is adjoined to the part of tail section is the arc, and two the staple leg the tail section is parallel to each other.

2. The staple according to claim 1, wherein the body segments include a first body segment adjacent the staple body and a second body segment adjacent the tail segment, the second body segment being arcuate, the first body segment having a cross-sectional area smaller than the cross-sectional area of the second body segment, and/or the first body segment having a cross-sectional area smaller than the cross-sectional area of the staple body.

3. The staple according to claim 1, wherein the junction of the body and the legs is radiused and/or the junction of the main body section and the tail section is radiused.

4. The staple according to claim 1,

the total length of the two nail legs is different, and the total length is the sum of the length of the main body section and the length of the tail section; and/or

The main body sections of the two staple legs are different in length; and/or

The tail sections of the two staple legs are of different lengths.

5. The staple according to claim 1,

the cross section of the main body section is circular or elliptical; and/or

The tail end of the tail section is provided with a guide blade.

6. The staple according to claim 1, wherein the staple is integrally formed of a biodegradable ferrous alloy material.

7. The staple according to claim 6, wherein said biodegradable iron alloy comprises 0.25-0.70% nitrogen and 15.00-35.00% manganese.

8. The staple according to claim 7, wherein said biodegradable iron alloy comprises 0.35-0.55% nitrogen and 18.00-25.00% manganese.

9. The staple according to claim 7, wherein said biodegradable iron alloy consists of 0.25-0.70% nitrogen, 15.00-35.00% manganese, less than 0.01% sulfur, less than 0.025% phosphorus and the balance iron.

10. The staple according to claim 7, wherein the microstructure of the biodegradable ferrous alloy is single phase austenite.